GS_USB

GS_USB

[Max S.]

[-- Attachment #1: Type: text/plain, Size: 393 bytes --]

I forgot to set a subject for this email last time i sent it :/
It probably never made it out of anyone’s spam filters.
Here it is again

Hello All,

Whats the protocol for getting a driver into the mainline kernel?
I've reached a working and fairly stable state with the CAN adapter I'm
working on, and would like to get its driver mainlined.

Attached is a patch.

Thanks,
Max Schneider.


[-- Attachment #2: 0001-GS_USB-CAN-Driver.patch --]
[-- Type: text/x-patch, Size: 28070 bytes --]

From 2e4c4df9aae119279eb0913db0b7bc1d1025879a Mon Sep 17 00:00:00 2001
From: Maximilian Schneider <max@schneidersoft.net>
Date: Wed, 2 Oct 2013 18:48:26 +0000
Subject: [PATCH] GS_USB CAN Driver.


Signed-off-by: Maximilian Schneider <max@schneidersoft.net>
---
 drivers/net/can/usb/Kconfig  |    8 +
 drivers/net/can/usb/Makefile |    1 +
 drivers/net/can/usb/gs_usb.c | 1121 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 1130 insertions(+)
 create mode 100644 drivers/net/can/usb/gs_usb.c

diff --git a/drivers/net/can/usb/Kconfig b/drivers/net/can/usb/Kconfig
index fc96a3d..f5e3e8c 100644
--- a/drivers/net/can/usb/Kconfig
+++ b/drivers/net/can/usb/Kconfig
@@ -54,4 +54,12 @@ config CAN_8DEV_USB
 	  This driver supports the USB2CAN interface
 	  from 8 devices (http://www.8devices.com).
 
+config CAN_GS_USB
+	tristate "Geschwister Schneider UG interfaces"
+	---help---
+	  This driver supports the Geschwister Schneider USB/CAN devices.
+	  If unsure choose N,
+	  choose Y for built in support,
+	  M to compile as module (module will be named: gs_usb).
+
 endmenu
diff --git a/drivers/net/can/usb/Makefile b/drivers/net/can/usb/Makefile
index becef46..c21a521 100644
--- a/drivers/net/can/usb/Makefile
+++ b/drivers/net/can/usb/Makefile
@@ -7,5 +7,6 @@ obj-$(CONFIG_CAN_ESD_USB2) += esd_usb2.o
 obj-$(CONFIG_CAN_KVASER_USB) += kvaser_usb.o
 obj-$(CONFIG_CAN_PEAK_USB) += peak_usb/
 obj-$(CONFIG_CAN_8DEV_USB) += usb_8dev.o
+obj-$(CONFIG_CAN_GS_USB) += gs_usb.o
 
 ccflags-$(CONFIG_CAN_DEBUG_DEVICES) := -DDEBUG
diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
new file mode 100644
index 0000000..558fc23
--- /dev/null
+++ b/drivers/net/can/usb/gs_usb.c
@@ -0,0 +1,1121 @@
+/* CAN driver for Geschwister Schneider USB/CAN devices.
+ *
+ * Copyright (C) 2013 Geschwister Schneider Technologie-,
+ * Entwicklungs- und Vertriebs UG (Haftungsbeschränkt).
+ *
+ * Many thanks to all socketcan devs!
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published
+ * by the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/init.h>
+#include <linux/signal.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/usb.h>
+
+#include <linux/can.h>
+#include <linux/can/dev.h>
+#include <linux/can/error.h>
+
+/* Device specific constants */
+#define USB_GSUSB_1_VENDOR_ID      0x1d50
+#define USB_GSUSB_1_PRODUCT_ID     0x606f
+
+#define GSUSB_ENDPOINT_IN          1
+#define GSUSB_ENDPOINT_OUT         2
+
+/* Device specific constants */
+enum gs_usb_breq {
+	GS_USB_BREQ_HOST_FORMAT = 0,
+	GS_USB_BREQ_BITTIMING,
+	GS_USB_BREQ_MODE,
+	GS_USB_BREQ_BERR,
+	GS_USB_BREQ_BT_CONST,
+	GS_USB_BREQ_DEVICE_CONFIG
+};
+
+enum gs_can_mode {
+	GS_CAN_MODE_RESET = 0,
+	GS_CAN_MODE_START
+};
+
+enum gs_can_state {
+	GS_CAN_STATE_ERROR_ACTIVE = 0,
+	GS_CAN_STATE_ERROR_WARNING,
+	GS_CAN_STATE_ERROR_PASSIVE,
+	GS_CAN_STATE_BUS_OFF,
+	GS_CAN_STATE_STOPPED,
+	GS_CAN_STATE_SLEEPING
+};
+
+/* data types passed between host and device */
+struct __packed gs_host_config {
+	u32 byte_order;
+};
+
+struct __packed gs_device_config {
+	u8 reserved1;
+	u8 reserved2;
+	u8 reserved3;
+	u8 icount;
+	u32 sw_version;
+	u32 hw_version;
+};
+
+#define GS_CAN_MODE_NORMAL               0
+#define GS_CAN_MODE_LISTEN_ONLY          (1<<0)
+#define GS_CAN_MODE_LOOP_BACK            (1<<1)
+#define GS_CAN_MODE_TRIPLE_SAMPLE        (1<<2)
+#define GS_CAN_MODE_ONE_SHOT             (1<<3)
+
+struct __packed gs_device_mode {
+	u32 mode;
+	u32 flags;
+};
+
+struct __packed gs_device_state {
+	u32 state;
+	u32 rxerr;
+	u32 txerr;
+};
+
+struct __packed gs_device_bittiming {
+	u32 prop_seg;
+	u32 phase_seg1;
+	u32 phase_seg2;
+	u32 sjw;
+	u32 brp;
+};
+
+#define GS_CAN_FEATURE_LISTEN_ONLY      (1<<0)
+#define GS_CAN_FEATURE_LOOP_BACK        (1<<1)
+#define GS_CAN_FEATURE_TRIPLE_SAMPLE    (1<<2)
+#define GS_CAN_FEATURE_ONE_SHOT         (1<<3)
+
+struct __packed gs_device_bt_const {
+	u32 feature;
+	u32 fclk_can;
+	u32 tseg1_min;
+	u32 tseg1_max;
+	u32 tseg2_min;
+	u32 tseg2_max;
+	u32 sjw_max;
+	u32 brp_min;
+	u32 brp_max;
+	u32 brp_inc;
+};
+
+#define GS_CAN_FLAG_OVERFLOW 1
+
+struct __packed gs_host_frame {
+	u32 echo_id;
+	u32 can_id;
+
+	u8 can_dlc;
+	u8 channel;
+	u8 flags;
+	u8 reserved;
+
+	u8 data[8];
+};
+
+#define GS_RX_BUFFER_SIZE sizeof(struct __packed gs_host_frame)
+
+/* Special address description flags for the CAN_ID */
+#define GS_EFF_FLAG 0x80000000U /* EFF/SFF is set in the MSB */
+#define GS_RTR_FLAG 0x40000000U /* remote transmission request */
+#define GS_ERR_FLAG 0x20000000U /* error frame */
+
+/* Valid bits in CAN ID for frame formats */
+#define GS_SFF_MASK 0x000007FFU /* standard frame format (SFF) */
+#define GS_EFF_MASK 0x1FFFFFFFU /* extended frame format (EFF) */
+#define GS_ERR_MASK 0x1FFFFFFFU /* omit EFF, RTR, ERR flags */
+
+/* FIXME: this macro is only a placeholder for a better function */
+#define CONVERT_FLAGS(x) x
+
+/* Only send a max of MAX_TX_URBS frames per channel to the device at a time. */
+#define MAX_TX_URBS 10
+/* Only launch a max of MAX_RX_URBS usb requests at a time. */
+#define MAX_RX_URBS 30
+/* Maximum number of interfaces the driver supports per device.
+ * Current hardware only supports 2 interfaces. The future may vary.
+ */
+#define MAX_INTF 2
+
+struct gs_tx_context {
+	struct gs_can *dev;
+	unsigned int echo_id;
+};
+
+struct gs_can {
+	struct can_priv can; /* must be the first member */
+
+	struct gs_usb *parent;
+
+	struct net_device *netdev;
+	struct usb_device *udev;
+	struct usb_interface *iface;
+
+	struct can_bittiming_const bt_const;
+	unsigned int channel;	/* channel number */
+
+	spinlock_t tx_ctx_lock;
+	struct gs_tx_context tx_context[MAX_TX_URBS];
+
+	struct usb_anchor tx_submitted;
+	atomic_t active_tx_urbs;
+};
+
+/* usb interface struct */
+struct gs_usb {
+	struct gs_can *canch[MAX_INTF];
+
+	struct usb_anchor rx_submitted;
+
+	atomic_t active_channels;
+};
+
+/* 'allocate' a tx context.
+ * returns a valid tx context or NULL if there is no space.
+ */
+static struct gs_tx_context *gs_alloc_tx_context(struct gs_can *dev)
+{
+	int i = 0;
+	unsigned long flags;
+	spin_lock_irqsave(&dev->tx_ctx_lock, flags);
+
+	for (; i < MAX_TX_URBS; i++) {
+		if (dev->tx_context[i].echo_id == MAX_TX_URBS) {
+			dev->tx_context[i].echo_id = i;
+			spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
+			return &dev->tx_context[i];
+		}
+	}
+
+	spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
+	return NULL;
+}
+
+/* releases a tx context
+ */
+static void gs_free_tx_context(struct gs_tx_context *txc)
+{
+	unsigned long flags;
+	spin_lock_irqsave(&txc->dev->tx_ctx_lock, flags);
+	txc->echo_id = MAX_TX_URBS;
+	spin_unlock_irqrestore(&txc->dev->tx_ctx_lock, flags);
+}
+
+/* Get a tx context by id.
+ */
+static struct gs_tx_context *gs_get_tx_context(
+	struct gs_can *dev,
+	unsigned int id)
+{
+	unsigned long flags;
+	spin_lock_irqsave(&dev->tx_ctx_lock, flags);
+	if (id < MAX_TX_URBS) {
+		if (dev->tx_context[id].echo_id == id) {
+			spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
+			return &dev->tx_context[id];
+		}
+	}
+	spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
+	return NULL;
+}
+
+/* Get a tx contexts id.
+ */
+static unsigned int gs_tx_context_id(struct gs_tx_context *txc)
+{
+	unsigned int id;
+	unsigned long flags;
+	spin_lock_irqsave(&txc->dev->tx_ctx_lock, flags);
+	id = txc->echo_id;
+	spin_unlock_irqrestore(&txc->dev->tx_ctx_lock, flags);
+	return id;
+}
+
+#define BUFFER_SIZE sizeof(struct gs_host_frame)
+
+static int gs_cmd_reset(struct gs_usb *gsusb, struct gs_can *gsdev)
+{
+	struct gs_device_mode *dm;
+	struct usb_interface *intf = gsdev->iface;
+	int rc;
+
+	dm = kzalloc(sizeof(*dm), GFP_KERNEL);
+	if (!dm)
+		return -ENOMEM;
+
+	dm->mode = GS_CAN_MODE_RESET;
+
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_MODE,
+			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			gsdev->channel,
+			0,
+			dm,
+			sizeof(*dm),
+			1000);
+
+	return rc;
+}
+
+/**************************** USB CALLBACKS **************************/
+static void gs_usb_recieve_bulk_callback(struct urb *urb)
+{
+	struct gs_usb *usbcan = urb->context;
+	struct gs_can *dev;
+	struct net_device *netdev;
+	int rc;
+	struct net_device_stats *stats;
+	struct gs_host_frame *hf = urb->transfer_buffer;
+	struct gs_tx_context *txc;
+
+	struct can_frame *cf;
+	struct sk_buff *skb;
+
+	BUG_ON(!usbcan);
+
+	switch (urb->status) {
+	case 0: /* success */
+		break;
+	case -ENOENT:
+	case -ESHUTDOWN:
+		return;
+	default:
+		/* printk(KERN_INFO "Rx URB aborted (%d)\n", urb->status); */
+		/* do not resubmit aborted urbs. eg: when device goes down */
+		return;
+	}
+
+	/* device reports out of range channel id */
+	if (hf->channel >= MAX_INTF)
+		/* printk(KERN_INFO "%d] strange channel #\n", hf->channel); */
+		goto resubmit_urb;
+
+	/* device reports bad channel id */
+	dev = usbcan->canch[hf->channel];
+	BUG_ON(!dev);
+
+	netdev = dev->netdev;
+	BUG_ON(!netdev);
+
+	if (!netif_device_present(netdev))
+		return;
+
+	stats = &dev->netdev->stats;
+
+	if (hf->echo_id == -1) { /* normal rx */
+		skb = alloc_can_skb(dev->netdev, &cf);
+		if (skb == NULL)
+			return;
+
+		cf->can_id = CONVERT_FLAGS(hf->can_id);
+		/* is it necessary to use get_can_dlc? */
+		cf->can_dlc = get_can_dlc(hf->can_dlc);
+		memcpy(cf->data, hf->data, 8);
+
+		netif_rx(skb);
+
+		netdev->stats.rx_packets++;
+		netdev->stats.rx_bytes += hf->can_dlc;
+	} else { /* echo_id = hf->echo_id */
+		if (hf->echo_id >= MAX_TX_URBS) {
+			netdev_info(netdev, "BAD echo %d\n", hf->echo_id);
+			goto resubmit_urb;
+		}
+
+		netdev->stats.tx_packets++;
+		netdev->stats.tx_bytes += hf->can_dlc;
+
+		txc = gs_get_tx_context(dev, hf->echo_id);
+
+		/* bad devices send bad echo_ids. */
+		if (!txc) {
+			netdev_info(netdev, "bad echo %d\n", hf->echo_id);
+			goto resubmit_urb;
+		}
+
+		can_get_echo_skb(netdev, gs_tx_context_id(txc));
+
+		gs_free_tx_context(txc);
+
+		netif_wake_queue(netdev);
+	}
+
+	if (hf->flags & GS_CAN_FLAG_OVERFLOW)
+		netdev_info(netdev, "overflow\n");
+
+
+resubmit_urb:
+	/* note: no urb refill... works for me */
+
+	rc = usb_submit_urb(urb, GFP_ATOMIC);
+
+	/* USB failure take down all interfaces */
+	if (rc == -ENODEV) {
+		for (rc = 0; rc < MAX_INTF; rc++) {
+			if (usbcan->canch[rc])
+				netif_device_detach(usbcan->canch[rc]->netdev);
+		}
+	}
+}
+
+static int gs_usb_set_bittiming(struct net_device *netdev)
+{
+	struct gs_can *dev = netdev_priv(netdev);
+	struct can_bittiming *bt = &dev->can.bittiming;
+	struct usb_interface *intf = dev->iface;
+	int rc;
+	struct gs_device_bittiming *dbt;
+
+	dbt = kmalloc(sizeof(*dbt), GFP_KERNEL);
+	if (!dbt)
+		return -ENOMEM;
+
+	dbt->prop_seg = bt->prop_seg;
+	dbt->phase_seg1 = bt->phase_seg1;
+	dbt->phase_seg2 = bt->phase_seg2;
+	dbt->sjw = bt->sjw;
+	dbt->brp = bt->brp;
+
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_BITTIMING,
+			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			dev->channel,
+			0,
+			dbt,
+			sizeof(*dbt),
+			1000);
+	if (rc < 0)
+		dev_warn(netdev->dev.parent, "Couldn't set bittimings %d", rc);
+
+	kfree(dbt);
+
+	return rc;
+}
+
+static int gs_usb_set_mode(struct net_device *netdev, enum can_mode mode)
+{
+	if (mode == CAN_MODE_START) {
+		netif_wake_queue(netdev);
+		return 0;
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static int gs_usb_get_state(const struct net_device *netdev,
+enum can_state *state)
+{
+
+	struct gs_can *dev = netdev_priv(netdev);
+	struct usb_interface *intf = dev->iface;
+	int rc;
+	struct gs_device_state *dstate;
+
+	dev_warn(netdev->dev.parent, "CAN state");
+
+	dstate = kmalloc(sizeof(*dstate), GFP_KERNEL);
+	if (!dstate)
+		return -ENOMEM;
+
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_BERR,
+			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			dev->channel,
+			0,
+			dstate,
+			sizeof(*dstate),
+			1000);
+
+	if (rc < 0) {
+		dev_warn(netdev->dev.parent, "Couldn't get state %d", rc);
+		kfree(dstate);
+		return rc;
+	}
+
+	switch (dstate->state) {
+	/* RX/TX error count < 96 */
+	case GS_CAN_STATE_ERROR_ACTIVE:
+		*state = CAN_STATE_ERROR_ACTIVE;
+		break;
+	/* RX/TX error count < 128 */
+	case GS_CAN_STATE_ERROR_WARNING:
+		*state = CAN_STATE_ERROR_WARNING;
+		break;
+	/* RX/TX error count < 256 */
+	case GS_CAN_STATE_ERROR_PASSIVE:
+		*state = CAN_STATE_ERROR_PASSIVE;
+		break;
+	/* RX/TX error count >= 256 */
+	case GS_CAN_STATE_BUS_OFF:
+		*state = CAN_STATE_BUS_OFF;
+		break;
+	/* Device is stopped */
+	case GS_CAN_STATE_STOPPED:
+		*state = CAN_STATE_STOPPED;
+		break;
+	/* Device is sleeping */
+	case GS_CAN_STATE_SLEEPING:
+		*state = CAN_STATE_SLEEPING;
+		break;
+	default:
+		kfree(dstate);
+		return -ENOTSUPP;
+	}
+
+	kfree(dstate);
+	return 0;
+}
+
+static int gs_usb_get_berr_counter(const struct net_device *netdev,
+struct can_berr_counter *bec)
+{
+	struct gs_can *dev = netdev_priv(netdev);
+	struct usb_interface *intf = dev->iface;
+	int rc;
+	struct gs_device_state *dstate;
+
+	dstate = kmalloc(sizeof(*dstate), GFP_KERNEL);
+	if (!dstate)
+		return -ENOMEM;
+
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_BERR,
+			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			dev->channel,
+			0,
+			dstate,
+			sizeof(*dstate),
+			1000);
+	if (rc < 0) {
+		dev_warn(netdev->dev.parent, "Couldn't get error counters %d",
+			rc);
+		kfree(dstate);
+		return rc;
+	}
+
+	bec->txerr = dstate->txerr;
+	bec->rxerr = dstate->rxerr;
+
+	kfree(dstate);
+	return 0;
+}
+
+static void gs_usb_xmit_callback(struct urb *urb)
+{
+	struct gs_tx_context *txc = urb->context;
+	struct gs_can *dev;
+	struct net_device *netdev;
+
+	BUG_ON(!txc);
+
+	dev = txc->dev;
+	BUG_ON(!dev);
+
+	netdev = dev->netdev;
+	BUG_ON(!netdev);
+
+	if (urb->status) {
+		dev_info(netdev->dev.parent, "%d] xmit err %d\n",
+			dev->channel, txc->echo_id);
+	}
+
+	usb_free_coherent(urb->dev,
+		urb->transfer_buffer_length,
+		urb->transfer_buffer,
+		urb->transfer_dma);
+
+	atomic_dec(&dev->active_tx_urbs);
+
+	if (!netif_device_present(netdev))
+		return;
+
+	if (netif_queue_stopped(netdev))
+		netif_wake_queue(netdev);
+}
+
+static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
+struct net_device *netdev)
+{
+	struct gs_can *dev = netdev_priv(netdev);
+	struct net_device_stats *stats = &dev->netdev->stats;
+	struct urb *urb;
+	struct gs_host_frame *hf;
+	struct can_frame *cf;
+	int rc;
+	unsigned int idx;
+	struct gs_tx_context *txc;
+
+	if (dev->can.ctrlmode&CAN_CTRLMODE_LISTENONLY)
+		return NETDEV_TX_BUSY;
+
+	if (can_dropped_invalid_skb(netdev, skb))
+		return NETDEV_TX_OK;
+
+	/* find an empty context to keep track of transmission */
+	txc = gs_alloc_tx_context(dev);
+	if (!txc)
+		return NETDEV_TX_BUSY;
+
+	/* create a URB, and a buffer for it */
+	urb = usb_alloc_urb(0, GFP_ATOMIC);
+	if (!urb) {
+		gs_free_tx_context(txc);
+		dev_err(netdev->dev.parent, "No memory left for URBs\n");
+		goto nomem;
+	}
+
+	hf = usb_alloc_coherent(dev->udev, sizeof(*hf), GFP_ATOMIC,
+		&urb->transfer_dma);
+	if (!hf) {
+		gs_free_tx_context(txc);
+		dev_err(netdev->dev.parent, "No memory left for USB buffer\n");
+		usb_free_urb(urb);
+		goto nomem;
+	}
+
+	cf = (struct can_frame *)skb->data;
+
+	idx = gs_tx_context_id(txc);
+
+	if (idx >= MAX_TX_URBS) {
+		dev_err(netdev->dev.parent, "Invalid tx context %d\n", idx);
+		usb_free_urb(urb);
+		usb_free_coherent(dev->udev,
+					sizeof(*hf),
+					hf,
+					urb->transfer_dma);
+		goto nomem;
+	}
+
+	hf->echo_id = idx;
+	hf->channel = dev->channel;
+
+	hf->can_id = CONVERT_FLAGS(cf->can_id);
+	hf->can_dlc = cf->can_dlc;
+	memcpy(hf->data, cf->data, 8);
+
+	usb_fill_bulk_urb(urb, dev->udev,
+			usb_sndbulkpipe(dev->udev, GSUSB_ENDPOINT_OUT),
+			hf,
+			sizeof(*hf),
+			gs_usb_xmit_callback,
+			txc);
+
+	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+	usb_anchor_urb(urb, &dev->tx_submitted);
+
+	can_put_echo_skb(skb, netdev, idx);
+
+	atomic_inc(&dev->active_tx_urbs);
+
+	rc = usb_submit_urb(urb, GFP_ATOMIC);
+	if (unlikely(rc)) {			/* usb send failed */
+		dev_err(netdev->dev.parent, "usb_submit failed %d\n", rc);
+
+		can_free_echo_skb(netdev, gs_tx_context_id(txc));
+		gs_free_tx_context(txc);
+
+		usb_unanchor_urb(urb);
+		usb_free_coherent(dev->udev,
+			sizeof(*hf),
+			hf,
+			urb->transfer_dma);
+
+		atomic_dec(&dev->active_tx_urbs);
+
+		if (rc == -ENODEV) {
+			netif_device_detach(netdev);
+		} else {
+			dev_warn(netdev->dev.parent, "Failed tx_urb %d\n", rc);
+
+			stats->tx_dropped++;
+		}
+	} else {
+		netdev->trans_start = jiffies;
+
+		/* Slow down tx path */
+		if (atomic_read(&dev->active_tx_urbs) >= MAX_TX_URBS)
+			netif_stop_queue(netdev);
+	}
+
+	/* let usb core take care of this urb */
+	usb_free_urb(urb);
+
+	return NETDEV_TX_OK;
+
+nomem:
+	dev_kfree_skb(skb);
+	stats->tx_dropped++;
+	return NETDEV_TX_OK;
+}
+
+static int gs_can_open(struct net_device *netdev)
+{
+	struct gs_can *dev = netdev_priv(netdev);
+	struct gs_usb *parent = dev->parent;
+	int rc, i;
+	struct gs_device_mode *dm;
+	u32 ctrlmode;
+
+	/* common open */
+	rc = open_candev(netdev);
+	if (rc)
+		return rc;
+
+	if (atomic_add_return(1, &parent->active_channels) == 1) {
+		dev_info(netdev->dev.parent, "Allocating rx URBs\n");
+		for (i = 0; i < MAX_RX_URBS; i++) {
+			struct urb *urb = NULL;
+			u8 *buf = NULL;
+
+			/* alloc rx urb */
+			urb = usb_alloc_urb(0, GFP_KERNEL);
+			if (!urb) {
+				dev_err(netdev->dev.parent,
+					"No memory left for URBs\n");
+				return -ENOMEM;
+			}
+
+			/* alloc rx buffer */
+			buf = usb_alloc_coherent(dev->udev,
+				BUFFER_SIZE,
+				GFP_KERNEL,
+				&urb->transfer_dma);
+			if (!buf) {
+				dev_err(netdev->dev.parent,
+					"No memory left for USB buffer\n");
+				usb_free_urb(urb);
+				return -ENOMEM;
+			}
+
+
+			/* fill, anchor, and submit rx urb */
+			usb_fill_bulk_urb(urb,
+					dev->udev,
+					usb_rcvbulkpipe(dev->udev,
+						GSUSB_ENDPOINT_IN),
+					buf,
+					BUFFER_SIZE,
+					gs_usb_recieve_bulk_callback,
+					parent
+					);
+			urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+
+			usb_anchor_urb(urb, &parent->rx_submitted);
+
+			rc = usb_submit_urb(urb, GFP_KERNEL);
+			if (rc) {
+				if (rc == -ENODEV)
+					netif_device_detach(dev->netdev);
+
+				usb_unanchor_urb(urb);
+				break;
+			}
+
+			/* Drop reference,
+			 * USB core will take care of freeing it
+			 */
+			usb_free_urb(urb);
+		}
+	}
+
+	dm = kmalloc(sizeof(*dm), GFP_KERNEL);
+	if (!dm)
+		return -ENOMEM;
+
+	/* flags */
+	ctrlmode = dev->can.ctrlmode;
+	dm->flags = 0;
+
+	if (ctrlmode & CAN_CTRLMODE_LOOPBACK)
+		dm->flags |= GS_CAN_MODE_LOOP_BACK;
+
+	else if (ctrlmode & CAN_CTRLMODE_LISTENONLY)
+		dm->flags |= GS_CAN_MODE_LISTEN_ONLY;
+
+
+	/* Controller is not allowed to retry TX
+	 * this mode is unavailable on atmels uc3c hardware
+	 */
+	if (ctrlmode & CAN_CTRLMODE_ONE_SHOT) {
+		dm->flags |= GS_CAN_MODE_ONE_SHOT;
+		dev_warn(netdev->dev.parent, "GS_USB_ONE_SHOT\n");
+	}
+
+	if (ctrlmode & CAN_CTRLMODE_3_SAMPLES) {
+		dm->flags |= GS_CAN_MODE_TRIPLE_SAMPLE;
+		dev_warn(netdev->dev.parent, "GS_USB_TRIPLE_SAMPLE\n");
+	}
+
+
+	/* finally start device */
+	dm->mode = GS_CAN_MODE_START;
+	rc = usb_control_msg(interface_to_usbdev(dev->iface),
+			usb_sndctrlpipe(interface_to_usbdev(dev->iface), 0),
+			GS_USB_BREQ_MODE,
+			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			dev->channel,
+			0,
+			dm,
+			sizeof(*dm),
+			1000);
+
+	kfree(dm);
+
+	if (rc < 0) {
+		dev_warn(netdev->dev.parent, "Couldn't start device %d\n", rc);
+		return rc;
+	}
+
+	/* check mode... */
+	dm = kmalloc(sizeof(*dm), GFP_KERNEL);
+	if (!dm)
+		return -ENOMEM;
+
+	rc = usb_control_msg(interface_to_usbdev(dev->iface),
+			usb_rcvctrlpipe(interface_to_usbdev(dev->iface), 0),
+			GS_USB_BREQ_MODE,
+			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			dev->channel,
+			0,
+			dm,
+			sizeof(*dm),
+			1000);
+
+	if (rc < 0) {
+		dev_warn(netdev->dev.parent, "Couldn't get device mode %d\n",
+			rc);
+		kfree(dm);
+		return rc;
+	}
+
+	kfree(dm);
+
+	dev->can.state = CAN_STATE_ERROR_ACTIVE;
+
+	netif_start_queue(netdev);
+
+	netdev_info(netdev, "CAN open\n");
+	return 0;
+}
+
+/* think: ip link set canx down */
+static int gs_can_close(struct net_device *netdev)
+{
+	int rc;
+	struct gs_can *dev = netdev_priv(netdev);
+	struct gs_usb *parent = dev->parent;
+
+	netif_stop_queue(netdev);
+
+	/* Stop polling */
+	if (atomic_dec_and_test(&parent->active_channels)) {
+		dev_info(netdev->dev.parent,
+			"Freeing rx usb memory\n");
+
+		usb_kill_anchored_urbs(&parent->rx_submitted);
+	}
+
+	rc = gs_cmd_reset(parent, dev);
+	if (rc < 0)
+		dev_warn(netdev->dev.parent, "Couldn't shutdown device %d", rc);
+
+	close_candev(netdev);
+
+	netdev_info(netdev, "CAN close\n");
+	return 0;
+}
+
+/******************************** USB ********************************/
+
+static const struct net_device_ops gs_usb_netdev_ops = {
+	.ndo_open = gs_can_open,
+	.ndo_stop = gs_can_close,
+	.ndo_start_xmit = gs_can_start_xmit,
+};
+
+static int gs_make_candev(struct gs_can **out, unsigned int channel,
+struct usb_interface *intf)
+{
+	struct gs_can *dev;
+	struct net_device *netdev;
+	int rc;
+	struct gs_device_bt_const *bt_const;
+
+	bt_const = kmalloc(sizeof(*bt_const), GFP_KERNEL);
+	if (!bt_const)
+		return -ENOMEM;
+
+	/* fetch bit timing constants */
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_BT_CONST,
+			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			channel,
+			0,
+			bt_const,
+			sizeof(*bt_const),
+			1000);
+
+	if (rc < 0) {
+		dev_err(&intf->dev,
+			"Couldn't get bit timing const for channel %d\n",
+			rc);
+		kfree(bt_const);
+		return rc;
+	}
+
+	dev_info(&intf->dev, "fclock: %d\n", bt_const->fclk_can);
+
+	/* create netdev */
+	netdev = alloc_candev(sizeof(struct gs_can), MAX_TX_URBS);
+	if (!netdev) {
+		dev_err(&intf->dev, "Couldn't alloc candev\n");
+		kfree(bt_const);
+		return -ENOMEM;
+	}
+
+	dev = netdev_priv(netdev);
+
+	netdev->netdev_ops = &gs_usb_netdev_ops;
+
+	netdev->flags |= IFF_ECHO; /* we support full roundtrip echo */
+
+	/* dev settup */
+	strcpy(dev->bt_const.name, "gs_usb");
+	dev->bt_const.tseg1_min = bt_const->tseg1_min;
+	dev->bt_const.tseg1_max = bt_const->tseg1_max;
+	dev->bt_const.tseg2_min = bt_const->tseg2_min;
+	dev->bt_const.tseg2_max = bt_const->tseg2_max;
+	dev->bt_const.sjw_max = bt_const->sjw_max;
+	dev->bt_const.brp_min = bt_const->brp_min;
+	dev->bt_const.brp_max = bt_const->brp_max;
+	dev->bt_const.brp_inc = bt_const->brp_inc;
+
+	dev->udev = interface_to_usbdev(intf);
+	dev->iface = intf;
+	dev->netdev = netdev;
+	dev->channel = channel;
+
+	init_usb_anchor(&dev->tx_submitted);
+	atomic_set(&dev->active_tx_urbs, 0);
+	spin_lock_init(&dev->tx_ctx_lock);
+	for (rc = 0; rc < MAX_TX_URBS; rc++) {
+		dev->tx_context[rc].dev = dev;
+		dev->tx_context[rc].echo_id = MAX_TX_URBS;
+	}
+
+	/* can settup */
+	dev->can.state = CAN_STATE_STOPPED;
+	dev->can.clock.freq = bt_const->fclk_can;
+	dev->can.bittiming_const = &dev->bt_const;
+	dev->can.do_set_bittiming = gs_usb_set_bittiming;
+	dev->can.do_set_mode = gs_usb_set_mode;
+	dev->can.do_get_state = gs_usb_get_state;
+	dev->can.do_get_berr_counter = gs_usb_get_berr_counter;
+
+	dev->can.ctrlmode_supported = 0;
+
+	if (bt_const->feature & GS_CAN_FEATURE_LISTEN_ONLY)
+		dev->can.ctrlmode_supported |= CAN_CTRLMODE_LISTENONLY;
+
+	if (bt_const->feature & GS_CAN_FEATURE_LOOP_BACK)
+		dev->can.ctrlmode_supported |= CAN_CTRLMODE_LOOPBACK;
+
+	if (bt_const->feature & GS_CAN_FEATURE_TRIPLE_SAMPLE)
+		dev->can.ctrlmode_supported |= CAN_CTRLMODE_3_SAMPLES;
+
+	if (bt_const->feature & GS_CAN_FEATURE_ONE_SHOT)
+		dev->can.ctrlmode_supported |= CAN_CTRLMODE_ONE_SHOT;
+
+	kfree(bt_const);
+
+	SET_NETDEV_DEV(netdev, &intf->dev);
+
+	rc = register_candev(dev->netdev);
+	if (rc) {
+		free_candev(dev->netdev);
+		dev_err(&intf->dev, "Couldn't register candev\n");
+		return rc;
+	}
+
+	*out = dev;
+	return 0;
+}
+
+static void gs_destroy_candev(struct gs_can *dev)
+{
+	unregister_candev(dev->netdev);
+	free_candev(dev->netdev);
+	usb_kill_anchored_urbs(&dev->tx_submitted);
+}
+
+static int gs_usb_probe(struct usb_interface *intf,
+const struct usb_device_id *id)
+{
+	struct gs_usb *dev;
+	int rc = -ENOMEM;
+	unsigned int icount, i;
+	struct gs_host_config *hconf;
+	struct gs_device_config *dconf;
+
+	hconf = kmalloc(sizeof(*hconf), GFP_KERNEL);
+	if (!hconf)
+		return -ENOMEM;
+
+	hconf->byte_order = 0x0000beef;
+
+
+	/* send host config */
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_HOST_FORMAT,
+			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			1,
+			intf->altsetting[0].desc.bInterfaceNumber,
+			hconf,
+			sizeof(*hconf),
+			1000);
+
+	kfree(hconf);
+
+	if (rc < 0) {
+		dev_err(&intf->dev, "Couldn't send data format: %d\n",
+			rc);
+		return rc;
+	}
+
+
+	dconf = kmalloc(sizeof(*dconf), GFP_KERNEL);
+	if (!dconf)
+		return -ENOMEM;
+
+	/* read device config */
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_DEVICE_CONFIG,
+			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			1,
+			intf->altsetting[0].desc.bInterfaceNumber,
+			dconf,
+			sizeof(*dconf),
+			1000);
+	if (rc < 0) {
+		dev_err(&intf->dev, "Couldn't recieve device config: %d\n",
+			rc);
+		return rc;
+	}
+
+	icount = dconf->icount+1;
+	kfree(dconf);
+
+	dev_info(&intf->dev, "Configuring for %d interfaces\n", icount);
+
+	if (icount > MAX_INTF) {
+		dev_err(&intf->dev,
+			"Driver cannot handle more that %d Can interfaces\n",
+			MAX_INTF);
+		return -EINVAL;
+	}
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	init_usb_anchor(&dev->rx_submitted);
+
+	atomic_set(&dev->active_channels, 0);
+
+	usb_set_intfdata(intf, dev);
+
+	for (i = 0; i < icount; i++) {
+		rc = gs_make_candev(&dev->canch[i], i, intf);
+		if (rc) {
+			/* on failure destroy previously created candevs */
+			icount = i;
+			for (i = 0; i < icount; i++) {
+				gs_destroy_candev(dev->canch[i]);
+				dev->canch[icount] = NULL;
+			}
+			return rc;
+		}
+		dev->canch[i]->parent = dev;
+	}
+
+	dev_info(&intf->dev, "Probe\n");
+	return 0;
+}
+
+static void gs_usb_disconnect(struct usb_interface *intf)
+{
+	unsigned i;
+	struct gs_usb *dev = usb_get_intfdata(intf);
+	usb_set_intfdata(intf, NULL);
+
+	if (!dev) {
+		dev_info(&intf->dev, "Disconnect (nodata)\n");
+		return;
+	}
+
+	for (i = 0; i < MAX_INTF; i++) {
+		struct gs_can *can = dev->canch[i];
+
+		if (!can)
+			continue;
+
+		gs_destroy_candev(can);
+	}
+
+	usb_kill_anchored_urbs(&dev->rx_submitted);
+
+	dev_info(&intf->dev, "Disconnect\n");
+}
+
+MODULE_DEVICE_TABLE(usb, gs_usb_table);
+
+static struct usb_device_id gs_usb_table[] = {
+	{USB_DEVICE(USB_GSUSB_1_VENDOR_ID, USB_GSUSB_1_PRODUCT_ID)},
+	{} /* Terminating entry */
+};
+
+static struct usb_driver gs_usb_driver = {
+	.name       = "gs_usb",
+	.probe      = gs_usb_probe,
+	.disconnect = gs_usb_disconnect,
+	.id_table   = gs_usb_table
+};
+
+static int __init gs_usb_init(void)
+{
+	return usb_register(&gs_usb_driver);
+}
+
+static void __exit gs_usb_exit(void)
+{
+	usb_deregister(&gs_usb_driver);
+}
+
+module_init(gs_usb_init);
+module_exit(gs_usb_exit);
+
+MODULE_AUTHOR("Maximilian Schneider <mws@schneidersoft.net>");
+MODULE_DESCRIPTION(
+"Socket CAN device driver for Geschwister Schneider Technologie-, "
+"Entwicklungs- und Vertriebs UG. USB2.0 to CAN interfaces.");
+MODULE_LICENSE("GPL v2");
+
-- 
1.7.10.4

Re: GS_USB

[Marc Kleine-Budde]

[-- Attachment #1: Type: text/plain, Size: 943 bytes --]

On 10/04/2013 02:31 PM, Max S. wrote:
> I forgot to set a subject for this email last time i sent it :/
> It probably never made it out of anyone’s spam filters.
> Here it is again
> 
> Hello All,
> 
> Whats the protocol for getting a driver into the mainline kernel?

Posting the driver, inline not attached, is preferred. Nagging the
maintainers after some days if they are not responding :)

> I've reached a working and fairly stable state with the CAN adapter I'm
> working on, and would like to get its driver mainlined.

I'm currently working on the CAN subsystem, too. I think find some time
during the weekend to look at your code.

Marc
-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 259 bytes --]

Re: GS_USB

[Wolfgang Grandegger]

On 10/04/2013 02:31 PM, Max S. wrote:
> I forgot to set a subject for this email last time i sent it :/
> It probably never made it out of anyone’s spam filters.
> Here it is again
> 
> Hello All,
> 
> Whats the protocol for getting a driver into the mainline kernel?

Simply post it here "inline" on the mailing list after you have done the
usual checkpatch.pl validation.

> I've reached a working and fairly stable state with the CAN adapter I'm
> working on, and would like to get its driver mainlined.
> 
> Attached is a patch.

I inlined it here for review:

>>From 2e4c4df9aae119279eb0913db0b7bc1d1025879a Mon Sep 17 00:00:00 2001
> From: Maximilian Schneider <max@schneidersoft.net>
> Date: Wed, 2 Oct 2013 18:48:26 +0000
> Subject: [PATCH] GS_USB CAN Driver.

A few more words here about the device and this driver are welcome.

> 
> Signed-off-by: Maximilian Schneider <max@schneidersoft.net>
> ---
>  drivers/net/can/usb/Kconfig  |    8 +
>  drivers/net/can/usb/Makefile |    1 +
>  drivers/net/can/usb/gs_usb.c | 1121 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 1130 insertions(+)
>  create mode 100644 drivers/net/can/usb/gs_usb.c
> 
> diff --git a/drivers/net/can/usb/Kconfig b/drivers/net/can/usb/Kconfig
> index fc96a3d..f5e3e8c 100644
> --- a/drivers/net/can/usb/Kconfig
> +++ b/drivers/net/can/usb/Kconfig
> @@ -54,4 +54,12 @@ config CAN_8DEV_USB
>  	  This driver supports the USB2CAN interface
>  	  from 8 devices (http://www.8devices.com).
>  
> +config CAN_GS_USB
> +	tristate "Geschwister Schneider UG interfaces"
> +	---help---
> +	  This driver supports the Geschwister Schneider USB/CAN devices.
> +	  If unsure choose N,
> +	  choose Y for built in support,
> +	  M to compile as module (module will be named: gs_usb).
> +
>  endmenu
> diff --git a/drivers/net/can/usb/Makefile b/drivers/net/can/usb/Makefile
> index becef46..c21a521 100644
> --- a/drivers/net/can/usb/Makefile
> +++ b/drivers/net/can/usb/Makefile
> @@ -7,5 +7,6 @@ obj-$(CONFIG_CAN_ESD_USB2) += esd_usb2.o
>  obj-$(CONFIG_CAN_KVASER_USB) += kvaser_usb.o
>  obj-$(CONFIG_CAN_PEAK_USB) += peak_usb/
>  obj-$(CONFIG_CAN_8DEV_USB) += usb_8dev.o
> +obj-$(CONFIG_CAN_GS_USB) += gs_usb.o
>  
>  ccflags-$(CONFIG_CAN_DEBUG_DEVICES) := -DDEBUG
> diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
> new file mode 100644
> index 0000000..558fc23
> --- /dev/null
> +++ b/drivers/net/can/usb/gs_usb.c
> @@ -0,0 +1,1121 @@
> +/* CAN driver for Geschwister Schneider USB/CAN devices.
> + *
> + * Copyright (C) 2013 Geschwister Schneider Technologie-,
> + * Entwicklungs- und Vertriebs UG (Haftungsbeschränkt).
> + *
> + * Many thanks to all socketcan devs!
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License as published
> + * by the Free Software Foundation; version 2 of the License.
> + *
> + * This program is distributed in the hope that it will be useful, but
> + * WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * General Public License for more details.
> + */
> +
> +#include <linux/init.h>
> +#include <linux/signal.h>
> +#include <linux/module.h>
> +#include <linux/netdevice.h>
> +#include <linux/usb.h>
> +
> +#include <linux/can.h>
> +#include <linux/can/dev.h>
> +#include <linux/can/error.h>
> +
> +/* Device specific constants */
> +#define USB_GSUSB_1_VENDOR_ID      0x1d50
> +#define USB_GSUSB_1_PRODUCT_ID     0x606f
> +
> +#define GSUSB_ENDPOINT_IN          1
> +#define GSUSB_ENDPOINT_OUT         2
> +
> +/* Device specific constants */
> +enum gs_usb_breq {
> +	GS_USB_BREQ_HOST_FORMAT = 0,
> +	GS_USB_BREQ_BITTIMING,
> +	GS_USB_BREQ_MODE,
> +	GS_USB_BREQ_BERR,
> +	GS_USB_BREQ_BT_CONST,
> +	GS_USB_BREQ_DEVICE_CONFIG
> +};
> +
> +enum gs_can_mode {
> +	GS_CAN_MODE_RESET = 0,
> +	GS_CAN_MODE_START
> +};
> +
> +enum gs_can_state {
> +	GS_CAN_STATE_ERROR_ACTIVE = 0,
> +	GS_CAN_STATE_ERROR_WARNING,
> +	GS_CAN_STATE_ERROR_PASSIVE,
> +	GS_CAN_STATE_BUS_OFF,
> +	GS_CAN_STATE_STOPPED,
> +	GS_CAN_STATE_SLEEPING
> +};
> +
> +/* data types passed between host and device */
> +struct __packed gs_host_config {
> +	u32 byte_order;
> +};
> +
> +struct __packed gs_device_config {
> +	u8 reserved1;
> +	u8 reserved2;
> +	u8 reserved3;
> +	u8 icount;
> +	u32 sw_version;
> +	u32 hw_version;
> +};
> +
> +#define GS_CAN_MODE_NORMAL               0
> +#define GS_CAN_MODE_LISTEN_ONLY          (1<<0)
> +#define GS_CAN_MODE_LOOP_BACK            (1<<1)
> +#define GS_CAN_MODE_TRIPLE_SAMPLE        (1<<2)
> +#define GS_CAN_MODE_ONE_SHOT             (1<<3)
> +
> +struct __packed gs_device_mode {
> +	u32 mode;
> +	u32 flags;
> +};
> +
> +struct __packed gs_device_state {
> +	u32 state;
> +	u32 rxerr;
> +	u32 txerr;
> +};
> +
> +struct __packed gs_device_bittiming {
> +	u32 prop_seg;
> +	u32 phase_seg1;
> +	u32 phase_seg2;
> +	u32 sjw;
> +	u32 brp;
> +};
> +
> +#define GS_CAN_FEATURE_LISTEN_ONLY      (1<<0)
> +#define GS_CAN_FEATURE_LOOP_BACK        (1<<1)
> +#define GS_CAN_FEATURE_TRIPLE_SAMPLE    (1<<2)
> +#define GS_CAN_FEATURE_ONE_SHOT         (1<<3)
> +
> +struct __packed gs_device_bt_const {
> +	u32 feature;
> +	u32 fclk_can;
> +	u32 tseg1_min;
> +	u32 tseg1_max;
> +	u32 tseg2_min;
> +	u32 tseg2_max;
> +	u32 sjw_max;
> +	u32 brp_min;
> +	u32 brp_max;
> +	u32 brp_inc;
> +};
> +
> +#define GS_CAN_FLAG_OVERFLOW 1
> +
> +struct __packed gs_host_frame {
> +	u32 echo_id;
> +	u32 can_id;
> +
> +	u8 can_dlc;
> +	u8 channel;
> +	u8 flags;
> +	u8 reserved;
> +
> +	u8 data[8];
> +};
> +
> +#define GS_RX_BUFFER_SIZE sizeof(struct __packed gs_host_frame)
> +
> +/* Special address description flags for the CAN_ID */
> +#define GS_EFF_FLAG 0x80000000U /* EFF/SFF is set in the MSB */
> +#define GS_RTR_FLAG 0x40000000U /* remote transmission request */
> +#define GS_ERR_FLAG 0x20000000U /* error frame */
> +
> +/* Valid bits in CAN ID for frame formats */
> +#define GS_SFF_MASK 0x000007FFU /* standard frame format (SFF) */
> +#define GS_EFF_MASK 0x1FFFFFFFU /* extended frame format (EFF) */
> +#define GS_ERR_MASK 0x1FFFFFFFU /* omit EFF, RTR, ERR flags */
> +
> +/* FIXME: this macro is only a placeholder for a better function */
> +#define CONVERT_FLAGS(x) x

Please fix (== remove?).

> +/* Only send a max of MAX_TX_URBS frames per channel to the device at a time. */
> +#define MAX_TX_URBS 10
> +/* Only launch a max of MAX_RX_URBS usb requests at a time. */
> +#define MAX_RX_URBS 30
> +/* Maximum number of interfaces the driver supports per device.
> + * Current hardware only supports 2 interfaces. The future may vary.
> + */
> +#define MAX_INTF 2
> +
> +struct gs_tx_context {
> +	struct gs_can *dev;
> +	unsigned int echo_id;
> +};
> +
> +struct gs_can {
> +	struct can_priv can; /* must be the first member */
> +
> +	struct gs_usb *parent;
> +
> +	struct net_device *netdev;
> +	struct usb_device *udev;
> +	struct usb_interface *iface;
> +
> +	struct can_bittiming_const bt_const;
> +	unsigned int channel;	/* channel number */
> +
> +	spinlock_t tx_ctx_lock;

Please briefly describe what the lock is used for.

> +	struct gs_tx_context tx_context[MAX_TX_URBS];
> +
> +	struct usb_anchor tx_submitted;
> +	atomic_t active_tx_urbs;
> +};
> +
> +/* usb interface struct */
> +struct gs_usb {
> +	struct gs_can *canch[MAX_INTF];
> +
> +	struct usb_anchor rx_submitted;
> +
> +	atomic_t active_channels;
> +};
> +
> +/* 'allocate' a tx context.
> + * returns a valid tx context or NULL if there is no space.
> + */
> +static struct gs_tx_context *gs_alloc_tx_context(struct gs_can *dev)
> +{
> +	int i = 0;
> +	unsigned long flags;
> +	spin_lock_irqsave(&dev->tx_ctx_lock, flags);
> +
> +	for (; i < MAX_TX_URBS; i++) {
> +		if (dev->tx_context[i].echo_id == MAX_TX_URBS) {
> +			dev->tx_context[i].echo_id = i;
> +			spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
> +			return &dev->tx_context[i];
> +		}
> +	}
> +
> +	spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
> +	return NULL;
> +}
> +
> +/* releases a tx context
> + */
> +static void gs_free_tx_context(struct gs_tx_context *txc)
> +{
> +	unsigned long flags;

Empty line please.

> +	spin_lock_irqsave(&txc->dev->tx_ctx_lock, flags);
> +	txc->echo_id = MAX_TX_URBS;
> +	spin_unlock_irqrestore(&txc->dev->tx_ctx_lock, flags);
> +}
> +
> +/* Get a tx context by id.
> + */
> +static struct gs_tx_context *gs_get_tx_context(
> +	struct gs_can *dev,
> +	unsigned int id)
> +{
> +	unsigned long flags;

Ditto

> +	spin_lock_irqsave(&dev->tx_ctx_lock, flags);
> +	if (id < MAX_TX_URBS) {
> +		if (dev->tx_context[id].echo_id == id) {
> +			spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
> +			return &dev->tx_context[id];
> +		}
> +	}
> +	spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
> +	return NULL;
> +}
> +
> +/* Get a tx contexts id.
> + */
> +static unsigned int gs_tx_context_id(struct gs_tx_context *txc)
> +{
> +	unsigned int id;
> +	unsigned long flags;

Ditto.

> +	spin_lock_irqsave(&txc->dev->tx_ctx_lock, flags);
> +	id = txc->echo_id;
> +	spin_unlock_irqrestore(&txc->dev->tx_ctx_lock, flags);
> +	return id;
> +}
> +
> +#define BUFFER_SIZE sizeof(struct gs_host_frame)

I think sizeof is clear enough.

> +
> +static int gs_cmd_reset(struct gs_usb *gsusb, struct gs_can *gsdev)
> +{
> +	struct gs_device_mode *dm;
> +	struct usb_interface *intf = gsdev->iface;
> +	int rc;
> +
> +	dm = kzalloc(sizeof(*dm), GFP_KERNEL);
> +	if (!dm)
> +		return -ENOMEM;
> +
> +	dm->mode = GS_CAN_MODE_RESET;
> +
> +	rc = usb_control_msg(interface_to_usbdev(intf),
> +			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
> +			GS_USB_BREQ_MODE,
> +			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			gsdev->channel,
> +			0,
> +			dm,
> +			sizeof(*dm),
> +			1000);
> +
> +	return rc;
> +}
> +
> +/**************************** USB CALLBACKS **************************/
> +static void gs_usb_recieve_bulk_callback(struct urb *urb)
> +{
> +	struct gs_usb *usbcan = urb->context;
> +	struct gs_can *dev;
> +	struct net_device *netdev;
> +	int rc;
> +	struct net_device_stats *stats;
> +	struct gs_host_frame *hf = urb->transfer_buffer;
> +	struct gs_tx_context *txc;
> +
> +	struct can_frame *cf;
> +	struct sk_buff *skb;
> +
> +	BUG_ON(!usbcan);
> +
> +	switch (urb->status) {
> +	case 0: /* success */
> +		break;
> +	case -ENOENT:
> +	case -ESHUTDOWN:
> +		return;
> +	default:
> +		/* printk(KERN_INFO "Rx URB aborted (%d)\n", urb->status); */

Please remove. You have too much debug lines and printouts.

> +		/* do not resubmit aborted urbs. eg: when device goes down */
> +		return;
> +	}
> +
> +	/* device reports out of range channel id */
> +	if (hf->channel >= MAX_INTF)
> +		/* printk(KERN_INFO "%d] strange channel #\n", hf->channel); */

Ditto.

> +		goto resubmit_urb;
> +
> +	/* device reports bad channel id */
> +	dev = usbcan->canch[hf->channel];
> +	BUG_ON(!dev);
> +
> +	netdev = dev->netdev;
> +	BUG_ON(!netdev);
> +
> +	if (!netif_device_present(netdev))
> +		return;
> +
> +	stats = &dev->netdev->stats;
> +
> +	if (hf->echo_id == -1) { /* normal rx */
> +		skb = alloc_can_skb(dev->netdev, &cf);
> +		if (skb == NULL)
> +			return;
> +
> +		cf->can_id = CONVERT_FLAGS(hf->can_id);
> +		/* is it necessary to use get_can_dlc? */
> +		cf->can_dlc = get_can_dlc(hf->can_dlc);
> +		memcpy(cf->data, hf->data, 8);
> +
> +		netif_rx(skb);
> +
> +		netdev->stats.rx_packets++;
> +		netdev->stats.rx_bytes += hf->can_dlc;
> +	} else { /* echo_id = hf->echo_id */

s/=/==/

> +		if (hf->echo_id >= MAX_TX_URBS) {
> +			netdev_info(netdev, "BAD echo %d\n", hf->echo_id);
> +			goto resubmit_urb;
> +		}
> +
> +		netdev->stats.tx_packets++;
> +		netdev->stats.tx_bytes += hf->can_dlc;
> +
> +		txc = gs_get_tx_context(dev, hf->echo_id);
> +
> +		/* bad devices send bad echo_ids. */
> +		if (!txc) {
> +			netdev_info(netdev, "bad echo %d\n", hf->echo_id);

Isn't this an error or a warning, at least?

> +			goto resubmit_urb;
> +		}
> +
> +		can_get_echo_skb(netdev, gs_tx_context_id(txc));
> +
> +		gs_free_tx_context(txc);
> +
> +		netif_wake_queue(netdev);
> +	}
> +
> +	if (hf->flags & GS_CAN_FLAG_OVERFLOW)
> +		netdev_info(netdev, "overflow\n");

Is this a CAN message overflow? If yes please generate an error message
like for the SJA1000:

http://lxr.free-electrons.com/source/drivers/net/can/sja1000/sja1000.c#L391

> +
> +
> +resubmit_urb:
> +	/* note: no urb refill... works for me */
> +
> +	rc = usb_submit_urb(urb, GFP_ATOMIC);
> +
> +	/* USB failure take down all interfaces */
> +	if (rc == -ENODEV) {
> +		for (rc = 0; rc < MAX_INTF; rc++) {
> +			if (usbcan->canch[rc])
> +				netif_device_detach(usbcan->canch[rc]->netdev);
> +		}
> +	}
> +}
> +
> +static int gs_usb_set_bittiming(struct net_device *netdev)
> +{
> +	struct gs_can *dev = netdev_priv(netdev);
> +	struct can_bittiming *bt = &dev->can.bittiming;
> +	struct usb_interface *intf = dev->iface;
> +	int rc;
> +	struct gs_device_bittiming *dbt;
> +
> +	dbt = kmalloc(sizeof(*dbt), GFP_KERNEL);
> +	if (!dbt)
> +		return -ENOMEM;
> +
> +	dbt->prop_seg = bt->prop_seg;
> +	dbt->phase_seg1 = bt->phase_seg1;
> +	dbt->phase_seg2 = bt->phase_seg2;
> +	dbt->sjw = bt->sjw;
> +	dbt->brp = bt->brp;
> +
> +	rc = usb_control_msg(interface_to_usbdev(intf),
> +			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
> +			GS_USB_BREQ_BITTIMING,
> +			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			dev->channel,
> +			0,
> +			dbt,
> +			sizeof(*dbt),
> +			1000);
> +	if (rc < 0)
> +		dev_warn(netdev->dev.parent, "Couldn't set bittimings %d", rc);

netdev_err?

> +	kfree(dbt);
> +
> +	return rc;
> +}
> +
> +static int gs_usb_set_mode(struct net_device *netdev, enum can_mode mode)
> +{
> +	if (mode == CAN_MODE_START) {
> +		netif_wake_queue(netdev);
> +		return 0;
> +	}
> +
> +	return -EOPNOTSUPP;
> +}
> +
> +static int gs_usb_get_state(const struct net_device *netdev,
> +enum can_state *state)

Please use some indention here and in other similar places.

> +{
> +
> +	struct gs_can *dev = netdev_priv(netdev);
> +	struct usb_interface *intf = dev->iface;
> +	int rc;
> +	struct gs_device_state *dstate;
> +
> +	dev_warn(netdev->dev.parent, "CAN state");
> +
> +	dstate = kmalloc(sizeof(*dstate), GFP_KERNEL);
> +	if (!dstate)
> +		return -ENOMEM;
> +
> +	rc = usb_control_msg(interface_to_usbdev(intf),
> +			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
> +			GS_USB_BREQ_BERR,
> +			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			dev->channel,
> +			0,
> +			dstate,
> +			sizeof(*dstate),
> +			1000);
> +
> +	if (rc < 0) {
> +		dev_warn(netdev->dev.parent, "Couldn't get state %d", rc);
> +		kfree(dstate);
> +		return rc;
> +	}
> +
> +	switch (dstate->state) {
> +	/* RX/TX error count < 96 */
> +	case GS_CAN_STATE_ERROR_ACTIVE:
> +		*state = CAN_STATE_ERROR_ACTIVE;
> +		break;
> +	/* RX/TX error count < 128 */
> +	case GS_CAN_STATE_ERROR_WARNING:
> +		*state = CAN_STATE_ERROR_WARNING;
> +		break;
> +	/* RX/TX error count < 256 */
> +	case GS_CAN_STATE_ERROR_PASSIVE:
> +		*state = CAN_STATE_ERROR_PASSIVE;
> +		break;
> +	/* RX/TX error count >= 256 */
> +	case GS_CAN_STATE_BUS_OFF:
> +		*state = CAN_STATE_BUS_OFF;
> +		break;
> +	/* Device is stopped */
> +	case GS_CAN_STATE_STOPPED:
> +		*state = CAN_STATE_STOPPED;
> +		break;
> +	/* Device is sleeping */
> +	case GS_CAN_STATE_SLEEPING:
> +		*state = CAN_STATE_SLEEPING;
> +		break;
> +	default:
> +		kfree(dstate);
> +		return -ENOTSUPP;
> +	}
> +
> +	kfree(dstate);
> +	return 0;
> +}

This callback is normally only needed if the state is not updated by the
driver via asynchronous events (interrupts).

> +static int gs_usb_get_berr_counter(const struct net_device *netdev,
> +struct can_berr_counter *bec)

Indention.

> +{
> +	struct gs_can *dev = netdev_priv(netdev);
> +	struct usb_interface *intf = dev->iface;
> +	int rc;
> +	struct gs_device_state *dstate;
> +
> +	dstate = kmalloc(sizeof(*dstate), GFP_KERNEL);
> +	if (!dstate)
> +		return -ENOMEM;
> +
> +	rc = usb_control_msg(interface_to_usbdev(intf),
> +			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
> +			GS_USB_BREQ_BERR,
> +			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			dev->channel,
> +			0,
> +			dstate,
> +			sizeof(*dstate),
> +			1000);
> +	if (rc < 0) {
> +		dev_warn(netdev->dev.parent, "Couldn't get error counters %d",
> +			rc);

dev_err or better netdev_err? Please use the netdev_* function whenever
possible, not only here.

> +		kfree(dstate);
> +		return rc;
> +	}
> +
> +	bec->txerr = dstate->txerr;
> +	bec->rxerr = dstate->rxerr;
> +
> +	kfree(dstate);
> +	return 0;
> +}
> +
> +static void gs_usb_xmit_callback(struct urb *urb)
> +{
> +	struct gs_tx_context *txc = urb->context;
> +	struct gs_can *dev;
> +	struct net_device *netdev;
> +
> +	BUG_ON(!txc);
> +
> +	dev = txc->dev;
> +	BUG_ON(!dev);
> +
> +	netdev = dev->netdev;
> +	BUG_ON(!netdev);

Too much sanity checks! Please reduce the number of BUG_ONs here and in
other places.

> +	if (urb->status) {
> +		dev_info(netdev->dev.parent, "%d] xmit err %d\n",
> +			dev->channel, txc->echo_id);

netdev_err?

> +	}
> +
> +	usb_free_coherent(urb->dev,
> +		urb->transfer_buffer_length,
> +		urb->transfer_buffer,
> +		urb->transfer_dma);
> +
> +	atomic_dec(&dev->active_tx_urbs);
> +
> +	if (!netif_device_present(netdev))
> +		return;
> +
> +	if (netif_queue_stopped(netdev))
> +		netif_wake_queue(netdev);
> +}
> +
> +static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
> +struct net_device *netdev)

Indention!

> +{
> +	struct gs_can *dev = netdev_priv(netdev);
> +	struct net_device_stats *stats = &dev->netdev->stats;
> +	struct urb *urb;
> +	struct gs_host_frame *hf;
> +	struct can_frame *cf;
> +	int rc;
> +	unsigned int idx;
> +	struct gs_tx_context *txc;
> +
> +	if (dev->can.ctrlmode&CAN_CTRLMODE_LISTENONLY)
> +		return NETDEV_TX_BUSY;

Hm, it's better not to start the TX queue in that case. But that's a
problem other driver do have as well.

> +
> +	if (can_dropped_invalid_skb(netdev, skb))
> +		return NETDEV_TX_OK;
> +
> +	/* find an empty context to keep track of transmission */
> +	txc = gs_alloc_tx_context(dev);
> +	if (!txc)
> +		return NETDEV_TX_BUSY;
> +
> +	/* create a URB, and a buffer for it */
> +	urb = usb_alloc_urb(0, GFP_ATOMIC);
> +	if (!urb) {
> +		gs_free_tx_context(txc);
> +		dev_err(netdev->dev.parent, "No memory left for URBs\n");
> +		goto nomem;
> +	}
> +
> +	hf = usb_alloc_coherent(dev->udev, sizeof(*hf), GFP_ATOMIC,
> +		&urb->transfer_dma);
> +	if (!hf) {
> +		gs_free_tx_context(txc);
> +		dev_err(netdev->dev.parent, "No memory left for USB buffer\n");
> +		usb_free_urb(urb);
> +		goto nomem;

It usual to use labels for cleanup to avoid code duplication, e.g. "goto
free_urb;".

> +	}
> +
> +	cf = (struct can_frame *)skb->data;
> +
> +	idx = gs_tx_context_id(txc);
> +
> +	if (idx >= MAX_TX_URBS) {

Can that happen?

> +		dev_err(netdev->dev.parent, "Invalid tx context %d\n", idx);
> +		usb_free_urb(urb);
> +		usb_free_coherent(dev->udev,
> +					sizeof(*hf),
> +					hf,
> +					urb->transfer_dma);

Label?

> +		goto nomem;
> +	}
> +
> +	hf->echo_id = idx;
> +	hf->channel = dev->channel;
> +
> +	hf->can_id = CONVERT_FLAGS(cf->can_id);
> +	hf->can_dlc = cf->can_dlc;
> +	memcpy(hf->data, cf->data, 8);
> +
> +	usb_fill_bulk_urb(urb, dev->udev,
> +			usb_sndbulkpipe(dev->udev, GSUSB_ENDPOINT_OUT),
> +			hf,
> +			sizeof(*hf),
> +			gs_usb_xmit_callback,
> +			txc);
> +
> +	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
> +	usb_anchor_urb(urb, &dev->tx_submitted);
> +
> +	can_put_echo_skb(skb, netdev, idx);
> +
> +	atomic_inc(&dev->active_tx_urbs);
> +
> +	rc = usb_submit_urb(urb, GFP_ATOMIC);
> +	if (unlikely(rc)) {			/* usb send failed */
> +		dev_err(netdev->dev.parent, "usb_submit failed %d\n", rc);

netdev_err!

> +		can_free_echo_skb(netdev, gs_tx_context_id(txc));
> +		gs_free_tx_context(txc);
> +
> +		usb_unanchor_urb(urb);
> +		usb_free_coherent(dev->udev,
> +			sizeof(*hf),
> +			hf,
> +			urb->transfer_dma);
> +
> +		atomic_dec(&dev->active_tx_urbs);
> +
> +		if (rc == -ENODEV) {
> +			netif_device_detach(netdev);
> +		} else {
> +			dev_warn(netdev->dev.parent, "Failed tx_urb %d\n", rc);

dev_err? Does it happen?

> +			stats->tx_dropped++;
> +		}
> +	} else {
> +		netdev->trans_start = jiffies;
> +
> +		/* Slow down tx path */
> +		if (atomic_read(&dev->active_tx_urbs) >= MAX_TX_URBS)
> +			netif_stop_queue(netdev);
> +	}
> +
> +	/* let usb core take care of this urb */
> +	usb_free_urb(urb);
> +
> +	return NETDEV_TX_OK;
> +
> +nomem:
> +	dev_kfree_skb(skb);
> +	stats->tx_dropped++;
> +	return NETDEV_TX_OK;
> +}
> +
> +static int gs_can_open(struct net_device *netdev)
> +{
> +	struct gs_can *dev = netdev_priv(netdev);
> +	struct gs_usb *parent = dev->parent;
> +	int rc, i;
> +	struct gs_device_mode *dm;
> +	u32 ctrlmode;
> +
> +	/* common open */
> +	rc = open_candev(netdev);
> +	if (rc)
> +		return rc;
> +
> +	if (atomic_add_return(1, &parent->active_channels) == 1) {
> +		dev_info(netdev->dev.parent, "Allocating rx URBs\n");

You are using to much debug messages, which are not really useful for
the user.

> +		for (i = 0; i < MAX_RX_URBS; i++) {
> +			struct urb *urb = NULL;
> +			u8 *buf = NULL;
> +
> +			/* alloc rx urb */
> +			urb = usb_alloc_urb(0, GFP_KERNEL);
> +			if (!urb) {
> +				dev_err(netdev->dev.parent,
> +					"No memory left for URBs\n");

close_candev() is missing. Please use labels for cleanup.

> +				return -ENOMEM;
> +			}
> +
> +			/* alloc rx buffer */
> +			buf = usb_alloc_coherent(dev->udev,
> +				BUFFER_SIZE,
> +				GFP_KERNEL,
> +				&urb->transfer_dma);
> +			if (!buf) {
> +				dev_err(netdev->dev.parent,
> +					"No memory left for USB buffer\n");
> +				usb_free_urb(urb);
> +				return -ENOMEM;
> +			}
> +
> +
> +			/* fill, anchor, and submit rx urb */
> +			usb_fill_bulk_urb(urb,
> +					dev->udev,
> +					usb_rcvbulkpipe(dev->udev,
> +						GSUSB_ENDPOINT_IN),
> +					buf,
> +					BUFFER_SIZE,
> +					gs_usb_recieve_bulk_callback,
> +					parent
> +					);
> +			urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
> +
> +			usb_anchor_urb(urb, &parent->rx_submitted);
> +
> +			rc = usb_submit_urb(urb, GFP_KERNEL);
> +			if (rc) {
> +				if (rc == -ENODEV)
> +					netif_device_detach(dev->netdev);
> +
> +				usb_unanchor_urb(urb);
> +				break;
> +			}
> +
> +			/* Drop reference,
> +			 * USB core will take care of freeing it
> +			 */
> +			usb_free_urb(urb);
> +		}
> +	}
> +
> +	dm = kmalloc(sizeof(*dm), GFP_KERNEL);
> +	if (!dm)
> +		return -ENOMEM;

Cleanup?

> +
> +	/* flags */
> +	ctrlmode = dev->can.ctrlmode;
> +	dm->flags = 0;
> +
> +	if (ctrlmode & CAN_CTRLMODE_LOOPBACK)
> +		dm->flags |= GS_CAN_MODE_LOOP_BACK;
> +
> +	else if (ctrlmode & CAN_CTRLMODE_LISTENONLY)
> +		dm->flags |= GS_CAN_MODE_LISTEN_ONLY;
> +
> +
> +	/* Controller is not allowed to retry TX
> +	 * this mode is unavailable on atmels uc3c hardware
> +	 */
> +	if (ctrlmode & CAN_CTRLMODE_ONE_SHOT) {
> +		dm->flags |= GS_CAN_MODE_ONE_SHOT;
> +		dev_warn(netdev->dev.parent, "GS_USB_ONE_SHOT\n");

Why a warning? I think you can remove this message.

> +	}
> +
> +	if (ctrlmode & CAN_CTRLMODE_3_SAMPLES) {
> +		dm->flags |= GS_CAN_MODE_TRIPLE_SAMPLE;
> +		dev_warn(netdev->dev.parent, "GS_USB_TRIPLE_SAMPLE\n");

Ditto.

> +	}
> +
> +
> +	/* finally start device */
> +	dm->mode = GS_CAN_MODE_START;
> +	rc = usb_control_msg(interface_to_usbdev(dev->iface),
> +			usb_sndctrlpipe(interface_to_usbdev(dev->iface), 0),
> +			GS_USB_BREQ_MODE,
> +			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			dev->channel,
> +			0,
> +			dm,
> +			sizeof(*dm),
> +			1000);
> +
> +	kfree(dm);
> +
> +	if (rc < 0) {
> +		dev_warn(netdev->dev.parent, "Couldn't start device %d\n", rc);

netdev_err?

> +		return rc;
> +	}
> +
> +	/* check mode... */
> +	dm = kmalloc(sizeof(*dm), GFP_KERNEL);
> +	if (!dm)
> +		return -ENOMEM;

No need to re-allocate "dm".

> +	rc = usb_control_msg(interface_to_usbdev(dev->iface),
> +			usb_rcvctrlpipe(interface_to_usbdev(dev->iface), 0),
> +			GS_USB_BREQ_MODE,
> +			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			dev->channel,
> +			0,
> +			dm,
> +			sizeof(*dm),
> +			1000);
> +
> +	if (rc < 0) {
> +		dev_warn(netdev->dev.parent, "Couldn't get device mode %d\n",
> +			rc);

netdev_err?

> +		kfree(dm);
> +		return rc;
> +	}
> +
> +	kfree(dm);

Again, please use labels to simplify your cleanup code.

> +
> +	dev->can.state = CAN_STATE_ERROR_ACTIVE;
> +
> +	netif_start_queue(netdev);
> +
> +	netdev_info(netdev, "CAN open\n");

You are too verbose. Please remove.

> +	return 0;
> +}
> +
> +/* think: ip link set canx down */

What do you mean?

> +static int gs_can_close(struct net_device *netdev)
> +{
> +	int rc;
> +	struct gs_can *dev = netdev_priv(netdev);
> +	struct gs_usb *parent = dev->parent;
> +
> +	netif_stop_queue(netdev);
> +
> +	/* Stop polling */
> +	if (atomic_dec_and_test(&parent->active_channels)) {
> +		dev_info(netdev->dev.parent,
> +			"Freeing rx usb memory\n");

You are too verbose. Please remove.

> +		usb_kill_anchored_urbs(&parent->rx_submitted);
> +	}
> +
> +	rc = gs_cmd_reset(parent, dev);
> +	if (rc < 0)
> +		dev_warn(netdev->dev.parent, "Couldn't shutdown device %d", rc);

netdev_err?

> +	close_candev(netdev);
> +
> +	netdev_info(netdev, "CAN close\n");

You are too verbose. Please remove.

> +	return 0;
> +}
> +
> +/******************************** USB ********************************/
> +
> +static const struct net_device_ops gs_usb_netdev_ops = {
> +	.ndo_open = gs_can_open,
> +	.ndo_stop = gs_can_close,
> +	.ndo_start_xmit = gs_can_start_xmit,
> +};
> +
> +static int gs_make_candev(struct gs_can **out, unsigned int channel,
> +struct usb_interface *intf)

Indention!

> +{
> +	struct gs_can *dev;
> +	struct net_device *netdev;
> +	int rc;
> +	struct gs_device_bt_const *bt_const;
> +
> +	bt_const = kmalloc(sizeof(*bt_const), GFP_KERNEL);
> +	if (!bt_const)
> +		return -ENOMEM;
> +
> +	/* fetch bit timing constants */
> +	rc = usb_control_msg(interface_to_usbdev(intf),
> +			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
> +			GS_USB_BREQ_BT_CONST,
> +			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			channel,
> +			0,
> +			bt_const,
> +			sizeof(*bt_const),
> +			1000);
> +
> +	if (rc < 0) {
> +		dev_err(&intf->dev,
> +			"Couldn't get bit timing const for channel %d\n",
> +			rc);
> +		kfree(bt_const);

labels for cleanup!

> +		return rc;
> +	}
> +
> +	dev_info(&intf->dev, "fclock: %d\n", bt_const->fclk_can);

Please remove. The use can query the information with "ip -d link show".

> +
> +	/* create netdev */
> +	netdev = alloc_candev(sizeof(struct gs_can), MAX_TX_URBS);
> +	if (!netdev) {
> +		dev_err(&intf->dev, "Couldn't alloc candev\n");
> +		kfree(bt_const);
> +		return -ENOMEM;
> +	}
> +
> +	dev = netdev_priv(netdev);
> +
> +	netdev->netdev_ops = &gs_usb_netdev_ops;
> +
> +	netdev->flags |= IFF_ECHO; /* we support full roundtrip echo */
> +
> +	/* dev settup */
> +	strcpy(dev->bt_const.name, "gs_usb");
> +	dev->bt_const.tseg1_min = bt_const->tseg1_min;
> +	dev->bt_const.tseg1_max = bt_const->tseg1_max;
> +	dev->bt_const.tseg2_min = bt_const->tseg2_min;
> +	dev->bt_const.tseg2_max = bt_const->tseg2_max;
> +	dev->bt_const.sjw_max = bt_const->sjw_max;
> +	dev->bt_const.brp_min = bt_const->brp_min;
> +	dev->bt_const.brp_max = bt_const->brp_max;
> +	dev->bt_const.brp_inc = bt_const->brp_inc;

memcpy() or "dev->bt_const = bt_const->sjw_max;"?

> +
> +	dev->udev = interface_to_usbdev(intf);
> +	dev->iface = intf;
> +	dev->netdev = netdev;
> +	dev->channel = channel;
> +
> +	init_usb_anchor(&dev->tx_submitted);
> +	atomic_set(&dev->active_tx_urbs, 0);
> +	spin_lock_init(&dev->tx_ctx_lock);
> +	for (rc = 0; rc < MAX_TX_URBS; rc++) {
> +		dev->tx_context[rc].dev = dev;
> +		dev->tx_context[rc].echo_id = MAX_TX_URBS;
> +	}
> +
> +	/* can settup */
> +	dev->can.state = CAN_STATE_STOPPED;
> +	dev->can.clock.freq = bt_const->fclk_can;
> +	dev->can.bittiming_const = &dev->bt_const;
> +	dev->can.do_set_bittiming = gs_usb_set_bittiming;
> +	dev->can.do_set_mode = gs_usb_set_mode;
> +	dev->can.do_get_state = gs_usb_get_state;
> +	dev->can.do_get_berr_counter = gs_usb_get_berr_counter;
> +
> +	dev->can.ctrlmode_supported = 0;
> +
> +	if (bt_const->feature & GS_CAN_FEATURE_LISTEN_ONLY)
> +		dev->can.ctrlmode_supported |= CAN_CTRLMODE_LISTENONLY;
> +
> +	if (bt_const->feature & GS_CAN_FEATURE_LOOP_BACK)
> +		dev->can.ctrlmode_supported |= CAN_CTRLMODE_LOOPBACK;
> +
> +	if (bt_const->feature & GS_CAN_FEATURE_TRIPLE_SAMPLE)
> +		dev->can.ctrlmode_supported |= CAN_CTRLMODE_3_SAMPLES;
> +
> +	if (bt_const->feature & GS_CAN_FEATURE_ONE_SHOT)
> +		dev->can.ctrlmode_supported |= CAN_CTRLMODE_ONE_SHOT;
> +
> +	kfree(bt_const);
> +
> +	SET_NETDEV_DEV(netdev, &intf->dev);
> +
> +	rc = register_candev(dev->netdev);
> +	if (rc) {
> +		free_candev(dev->netdev);
> +		dev_err(&intf->dev, "Couldn't register candev\n");
> +		return rc;
> +	}
> +
> +	*out = dev;
> +	return 0;
> +}
> +
> +static void gs_destroy_candev(struct gs_can *dev)
> +{
> +	unregister_candev(dev->netdev);
> +	free_candev(dev->netdev);
> +	usb_kill_anchored_urbs(&dev->tx_submitted);
> +}
> +
> +static int gs_usb_probe(struct usb_interface *intf,
> +const struct usb_device_id *id)

Indention!

> +{
> +	struct gs_usb *dev;
> +	int rc = -ENOMEM;
> +	unsigned int icount, i;
> +	struct gs_host_config *hconf;
> +	struct gs_device_config *dconf;
> +
> +	hconf = kmalloc(sizeof(*hconf), GFP_KERNEL);
> +	if (!hconf)
> +		return -ENOMEM;
> +
> +	hconf->byte_order = 0x0000beef;
> +
> +
> +	/* send host config */
> +	rc = usb_control_msg(interface_to_usbdev(intf),
> +			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
> +			GS_USB_BREQ_HOST_FORMAT,
> +			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			1,
> +			intf->altsetting[0].desc.bInterfaceNumber,
> +			hconf,
> +			sizeof(*hconf),
> +			1000);
> +
> +	kfree(hconf);
> +
> +	if (rc < 0) {
> +		dev_err(&intf->dev, "Couldn't send data format: %d\n",
> +			rc);
> +		return rc;
> +	}
> +
> +
> +	dconf = kmalloc(sizeof(*dconf), GFP_KERNEL);
> +	if (!dconf)
> +		return -ENOMEM;
> +
> +	/* read device config */
> +	rc = usb_control_msg(interface_to_usbdev(intf),
> +			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
> +			GS_USB_BREQ_DEVICE_CONFIG,
> +			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			1,
> +			intf->altsetting[0].desc.bInterfaceNumber,
> +			dconf,
> +			sizeof(*dconf),
> +			1000);
> +	if (rc < 0) {
> +		dev_err(&intf->dev, "Couldn't recieve device config: %d\n",
> +			rc);

kfree(dconf); ?

> +		return rc;
> +	}
> +
> +	icount = dconf->icount+1;
> +	kfree(dconf);
> +
> +	dev_info(&intf->dev, "Configuring for %d interfaces\n", icount);
> +
> +	if (icount > MAX_INTF) {
> +		dev_err(&intf->dev,
> +			"Driver cannot handle more that %d Can interfaces\n",
> +			MAX_INTF);
> +		return -EINVAL;
> +	}
> +
> +	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
> +	init_usb_anchor(&dev->rx_submitted);
> +
> +	atomic_set(&dev->active_channels, 0);
> +
> +	usb_set_intfdata(intf, dev);
> +
> +	for (i = 0; i < icount; i++) {
> +		rc = gs_make_candev(&dev->canch[i], i, intf);
> +		if (rc) {
> +			/* on failure destroy previously created candevs */
> +			icount = i;
> +			for (i = 0; i < icount; i++) {
> +				gs_destroy_candev(dev->canch[i]);
> +				dev->canch[icount] = NULL;
> +			}
> +			return rc;
> +		}
> +		dev->canch[i]->parent = dev;
> +	}
> +
> +	dev_info(&intf->dev, "Probe\n");

One dev_info per probe is fine but it should provide more information.

> +	return 0;
> +}
> +
> +static void gs_usb_disconnect(struct usb_interface *intf)
> +{
> +	unsigned i;
> +	struct gs_usb *dev = usb_get_intfdata(intf);
> +	usb_set_intfdata(intf, NULL);
> +
> +	if (!dev) {
> +		dev_info(&intf->dev, "Disconnect (nodata)\n");

dev_err?

> +		return;
> +	}
> +
> +	for (i = 0; i < MAX_INTF; i++) {
> +		struct gs_can *can = dev->canch[i];
> +
> +		if (!can)
> +			continue;
> +
> +		gs_destroy_candev(can);
> +	}
> +
> +	usb_kill_anchored_urbs(&dev->rx_submitted);
> +
> +	dev_info(&intf->dev, "Disconnect\n");
> +}
> +
> +MODULE_DEVICE_TABLE(usb, gs_usb_table);
> +
> +static struct usb_device_id gs_usb_table[] = {
> +	{USB_DEVICE(USB_GSUSB_1_VENDOR_ID, USB_GSUSB_1_PRODUCT_ID)},
> +	{} /* Terminating entry */
> +};
> +
> +static struct usb_driver gs_usb_driver = {
> +	.name       = "gs_usb",
> +	.probe      = gs_usb_probe,
> +	.disconnect = gs_usb_disconnect,
> +	.id_table   = gs_usb_table
> +};
> +
> +static int __init gs_usb_init(void)
> +{
> +	return usb_register(&gs_usb_driver);
> +}
> +
> +static void __exit gs_usb_exit(void)
> +{
> +	usb_deregister(&gs_usb_driver);
> +}
> +
> +module_init(gs_usb_init);
> +module_exit(gs_usb_exit);
> +
> +MODULE_AUTHOR("Maximilian Schneider <mws@schneidersoft.net>");
> +MODULE_DESCRIPTION(
> +"Socket CAN device driver for Geschwister Schneider Technologie-, "
> +"Entwicklungs- und Vertriebs UG. USB2.0 to CAN interfaces.");
> +MODULE_LICENSE("GPL v2");
> +
> -- 
> 1.7.10.4

Wolfgang.

Re: GS_USB

[Max S.]

Hello Wolfgang,

Here is the cleaned up patch incorporating your suggestions.

I am using "git commit --amend" to compile changes into a single patch.
Is this the correct method?

From 98ba2435f65df418f64c05a38ff4c013df98fdb4 Mon Sep 17 00:00:00 2001
From: Maximilian Schneider <max@schneidersoft.net>
Date: Mon, 7 Oct 2013 14:02:53 +0000
Subject: [PATCH] GS_USB CAN driver


Signed-off-by: Maximilian Schneider <max@schneidersoft.net>
---
 drivers/net/can/usb/Kconfig  |    8 +
 drivers/net/can/usb/Makefile |    1 +
 drivers/net/can/usb/gs_usb.c | 1118
++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 1127 insertions(+)
 create mode 100644 drivers/net/can/usb/gs_usb.c

diff --git a/drivers/net/can/usb/Kconfig b/drivers/net/can/usb/Kconfig
index fc96a3d..f5e3e8c 100644
--- a/drivers/net/can/usb/Kconfig
+++ b/drivers/net/can/usb/Kconfig
@@ -54,4 +54,12 @@ config CAN_8DEV_USB
 	  This driver supports the USB2CAN interface
 	  from 8 devices (http://www.8devices.com).
 
+config CAN_GS_USB
+	tristate "Geschwister Schneider UG interfaces"
+	---help---
+	  This driver supports the Geschwister Schneider USB/CAN devices.
+	  If unsure choose N,
+	  choose Y for built in support,
+	  M to compile as module (module will be named: gs_usb).
+
 endmenu
diff --git a/drivers/net/can/usb/Makefile b/drivers/net/can/usb/Makefile
index becef46..c21a521 100644
--- a/drivers/net/can/usb/Makefile
+++ b/drivers/net/can/usb/Makefile
@@ -7,5 +7,6 @@ obj-$(CONFIG_CAN_ESD_USB2) += esd_usb2.o
 obj-$(CONFIG_CAN_KVASER_USB) += kvaser_usb.o
 obj-$(CONFIG_CAN_PEAK_USB) += peak_usb/
 obj-$(CONFIG_CAN_8DEV_USB) += usb_8dev.o
+obj-$(CONFIG_CAN_GS_USB) += gs_usb.o
 
 ccflags-$(CONFIG_CAN_DEBUG_DEVICES) := -DDEBUG
diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
new file mode 100644
index 0000000..3f7a5a2
--- /dev/null
+++ b/drivers/net/can/usb/gs_usb.c
@@ -0,0 +1,1118 @@
+/* CAN driver for Geschwister Schneider USB/CAN devices.
+ *
+ * Copyright (C) 2013 Geschwister Schneider Technologie-,
+ * Entwicklungs- und Vertriebs UG (Haftungsbeschränkt).
+ *
+ * Many thanks to all socketcan devs!
+ *
+ * This program is free software; you can redistribute it and/or modify
it
+ * under the terms of the GNU General Public License as published
+ * by the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/init.h>
+#include <linux/signal.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/usb.h>
+
+#include <linux/can.h>
+#include <linux/can/dev.h>
+#include <linux/can/error.h>
+
+/* Device specific constants */
+#define USB_GSUSB_1_VENDOR_ID      0x1d50
+#define USB_GSUSB_1_PRODUCT_ID     0x606f
+
+#define GSUSB_ENDPOINT_IN          1
+#define GSUSB_ENDPOINT_OUT         2
+
+/* Device specific constants */
+enum gs_usb_breq {
+	GS_USB_BREQ_HOST_FORMAT = 0,
+	GS_USB_BREQ_BITTIMING,
+	GS_USB_BREQ_MODE,
+	GS_USB_BREQ_BERR,
+	GS_USB_BREQ_BT_CONST,
+	GS_USB_BREQ_DEVICE_CONFIG
+};
+
+enum gs_can_mode {
+	GS_CAN_MODE_RESET = 0,
+	GS_CAN_MODE_START
+};
+
+enum gs_can_state {
+	GS_CAN_STATE_ERROR_ACTIVE = 0,
+	GS_CAN_STATE_ERROR_WARNING,
+	GS_CAN_STATE_ERROR_PASSIVE,
+	GS_CAN_STATE_BUS_OFF,
+	GS_CAN_STATE_STOPPED,
+	GS_CAN_STATE_SLEEPING
+};
+
+/* data types passed between host and device */
+struct __packed gs_host_config {
+	u32 byte_order;
+};
+
+struct __packed gs_device_config {
+	u8 reserved1;
+	u8 reserved2;
+	u8 reserved3;
+	u8 icount;
+	u32 sw_version;
+	u32 hw_version;
+};
+
+#define GS_CAN_MODE_NORMAL               0
+#define GS_CAN_MODE_LISTEN_ONLY          (1<<0)
+#define GS_CAN_MODE_LOOP_BACK            (1<<1)
+#define GS_CAN_MODE_TRIPLE_SAMPLE        (1<<2)
+#define GS_CAN_MODE_ONE_SHOT             (1<<3)
+
+struct __packed gs_device_mode {
+	u32 mode;
+	u32 flags;
+};
+
+struct __packed gs_device_state {
+	u32 state;
+	u32 rxerr;
+	u32 txerr;
+};
+
+struct __packed gs_device_bittiming {
+	u32 prop_seg;
+	u32 phase_seg1;
+	u32 phase_seg2;
+	u32 sjw;
+	u32 brp;
+};
+
+#define GS_CAN_FEATURE_LISTEN_ONLY      (1<<0)
+#define GS_CAN_FEATURE_LOOP_BACK        (1<<1)
+#define GS_CAN_FEATURE_TRIPLE_SAMPLE    (1<<2)
+#define GS_CAN_FEATURE_ONE_SHOT         (1<<3)
+
+struct __packed gs_device_bt_const {
+	u32 feature;
+	u32 fclk_can;
+	u32 tseg1_min;
+	u32 tseg1_max;
+	u32 tseg2_min;
+	u32 tseg2_max;
+	u32 sjw_max;
+	u32 brp_min;
+	u32 brp_max;
+	u32 brp_inc;
+};
+
+#define GS_CAN_FLAG_OVERFLOW 1
+
+struct __packed gs_host_frame {
+	u32 echo_id;
+	u32 can_id;
+
+	u8 can_dlc;
+	u8 channel;
+	u8 flags;
+	u8 reserved;
+
+	u8 data[8];
+};
+
+/* Special address description flags for the CAN_ID */
+#define GS_EFF_FLAG 0x80000000U /* EFF/SFF is set in the MSB */
+#define GS_RTR_FLAG 0x40000000U /* remote transmission request */
+#define GS_ERR_FLAG 0x20000000U /* error frame */
+
+/* Valid bits in CAN ID for frame formats */
+#define GS_SFF_MASK 0x000007FFU /* standard frame format (SFF) */
+#define GS_EFF_MASK 0x1FFFFFFFU /* extended frame format (EFF) */
+#define GS_ERR_MASK 0x1FFFFFFFU /* omit EFF, RTR, ERR flags */
+
+/* Only send a max of MAX_TX_URBS frames per channel to the device at a
time. */
+#define MAX_TX_URBS 10
+/* Only launch a max of MAX_RX_URBS usb requests at a time. */
+#define MAX_RX_URBS 30
+/* Maximum number of interfaces the driver supports per device.
+ * Current hardware only supports 2 interfaces. The future may vary.
+ */
+#define MAX_INTF 2
+
+struct gs_tx_context {
+	struct gs_can *dev;
+	unsigned int echo_id;
+};
+
+struct gs_can {
+	struct can_priv can; /* must be the first member */
+
+	struct gs_usb *parent;
+
+	struct net_device *netdev;
+	struct usb_device *udev;
+	struct usb_interface *iface;
+
+	struct can_bittiming_const bt_const;
+	unsigned int channel;	/* channel number */
+
+	/* This lock prevents a race condition
+	 * between xmit and recieve.
+	 */
+	spinlock_t tx_ctx_lock;
+	struct gs_tx_context tx_context[MAX_TX_URBS];
+
+	struct usb_anchor tx_submitted;
+	atomic_t active_tx_urbs;
+};
+
+/* usb interface struct */
+struct gs_usb {
+	struct gs_can *canch[MAX_INTF];
+
+	struct usb_anchor rx_submitted;
+
+	atomic_t active_channels;
+};
+
+/* 'allocate' a tx context.
+ * returns a valid tx context or NULL if there is no space.
+ */
+static struct gs_tx_context *gs_alloc_tx_context(struct gs_can *dev)
+{
+	int i = 0;
+
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->tx_ctx_lock, flags);
+
+	for (; i < MAX_TX_URBS; i++) {
+		if (dev->tx_context[i].echo_id == MAX_TX_URBS) {
+			dev->tx_context[i].echo_id = i;
+			spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
+			return &dev->tx_context[i];
+		}
+	}
+
+	spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
+	return NULL;
+}
+
+/* releases a tx context
+ */
+static void gs_free_tx_context(struct gs_tx_context *txc)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&txc->dev->tx_ctx_lock, flags);
+	txc->echo_id = MAX_TX_URBS;
+	spin_unlock_irqrestore(&txc->dev->tx_ctx_lock, flags);
+}
+
+/* Get a tx context by id.
+ */
+static struct gs_tx_context *gs_get_tx_context(
+	struct gs_can *dev,
+	unsigned int id)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->tx_ctx_lock, flags);
+	if (id < MAX_TX_URBS) {
+		if (dev->tx_context[id].echo_id == id) {
+			spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
+			return &dev->tx_context[id];
+		}
+	}
+	spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
+	return NULL;
+}
+
+/* Get a tx contexts id.
+ */
+static unsigned int gs_tx_context_id(struct gs_tx_context *txc)
+{
+	unsigned int id;
+
+	unsigned long flags;
+
+	spin_lock_irqsave(&txc->dev->tx_ctx_lock, flags);
+	id = txc->echo_id;
+	spin_unlock_irqrestore(&txc->dev->tx_ctx_lock, flags);
+	return id;
+}
+
+static int gs_cmd_reset(struct gs_usb *gsusb, struct gs_can *gsdev)
+{
+	struct gs_device_mode *dm;
+	struct usb_interface *intf = gsdev->iface;
+	int rc;
+
+	dm = kzalloc(sizeof(*dm), GFP_KERNEL);
+	if (!dm)
+		return -ENOMEM;
+
+	dm->mode = GS_CAN_MODE_RESET;
+
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_MODE,
+			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			gsdev->channel,
+			0,
+			dm,
+			sizeof(*dm),
+			1000);
+
+	return rc;
+}
+
+/**************************** USB CALLBACKS **************************/
+static void gs_usb_recieve_bulk_callback(struct urb *urb)
+{
+	struct gs_usb *usbcan = urb->context;
+	struct gs_can *dev;
+	struct net_device *netdev;
+	int rc;
+	struct net_device_stats *stats;
+	struct gs_host_frame *hf = urb->transfer_buffer;
+	struct gs_tx_context *txc;
+
+	struct can_frame *cf;
+	struct sk_buff *skb;
+
+	BUG_ON(!usbcan);
+
+	switch (urb->status) {
+	case 0: /* success */
+		break;
+	case -ENOENT:
+	case -ESHUTDOWN:
+		return;
+	default:
+		/* do not resubmit aborted urbs. eg: when device goes down */
+		return;
+	}
+
+	/* device reports out of range channel id */
+	if (hf->channel >= MAX_INTF)
+		goto resubmit_urb;
+
+	/* device reports bad channel id */
+	dev = usbcan->canch[hf->channel];
+
+	netdev = dev->netdev;
+
+	if (!netif_device_present(netdev))
+		return;
+
+	stats = &dev->netdev->stats;
+
+	if (hf->echo_id == -1) { /* normal rx */
+		skb = alloc_can_skb(dev->netdev, &cf);
+		if (skb == NULL)
+			return;
+
+		cf->can_id = hf->can_id;
+		/* is it necessary to use get_can_dlc? */
+		cf->can_dlc = get_can_dlc(hf->can_dlc);
+		memcpy(cf->data, hf->data, 8);
+
+		netif_rx(skb);
+
+		netdev->stats.rx_packets++;
+		netdev->stats.rx_bytes += hf->can_dlc;
+	} else { /* echo_id == hf->echo_id */
+		if (hf->echo_id >= MAX_TX_URBS) {
+			netdev_err(netdev,
+				"Device sent an out of range echo id:%d\n",
+				hf->echo_id);
+			goto resubmit_urb;
+		}
+
+		netdev->stats.tx_packets++;
+		netdev->stats.tx_bytes += hf->can_dlc;
+
+		txc = gs_get_tx_context(dev, hf->echo_id);
+
+		/* bad devices send bad echo_ids. */
+		if (!txc) {
+			netdev_err(netdev,
+				"Device sent a bad echo id:%d\n",
+				hf->echo_id);
+			goto resubmit_urb;
+		}
+
+		can_get_echo_skb(netdev, gs_tx_context_id(txc));
+
+		gs_free_tx_context(txc);
+
+		netif_wake_queue(netdev);
+	}
+
+	if (hf->flags & GS_CAN_FLAG_OVERFLOW) {
+		skb = alloc_can_err_skb(netdev, &cf);
+		if (skb == NULL)
+			goto resubmit_urb;
+
+		cf->can_id |= CAN_ERR_CRTL;
+		cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
+		stats->rx_over_errors++;
+		stats->rx_errors++;
+		netif_rx(skb);
+	}
+
+
+resubmit_urb:
+	/* note: no urb refill... works for me */
+
+	rc = usb_submit_urb(urb, GFP_ATOMIC);
+
+	/* USB failure take down all interfaces */
+	if (rc == -ENODEV) {
+		for (rc = 0; rc < MAX_INTF; rc++) {
+			if (usbcan->canch[rc])
+				netif_device_detach(usbcan->canch[rc]->netdev);
+		}
+	}
+}
+
+static int gs_usb_set_bittiming(struct net_device *netdev)
+{
+	struct gs_can *dev = netdev_priv(netdev);
+	struct can_bittiming *bt = &dev->can.bittiming;
+	struct usb_interface *intf = dev->iface;
+	int rc;
+	struct gs_device_bittiming *dbt;
+
+	dbt = kmalloc(sizeof(*dbt), GFP_KERNEL);
+	if (!dbt)
+		return -ENOMEM;
+
+	dbt->prop_seg = bt->prop_seg;
+	dbt->phase_seg1 = bt->phase_seg1;
+	dbt->phase_seg2 = bt->phase_seg2;
+	dbt->sjw = bt->sjw;
+	dbt->brp = bt->brp;
+
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_BITTIMING,
+			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			dev->channel,
+			0,
+			dbt,
+			sizeof(*dbt),
+			1000);
+	if (rc < 0)
+		dev_err(netdev->dev.parent, "Couldn't set bittimings %d", rc);
+
+	kfree(dbt);
+
+	return rc;
+}
+
+static int gs_usb_set_mode(struct net_device *netdev, enum can_mode
mode)
+{
+	if (mode == CAN_MODE_START) {
+		netif_wake_queue(netdev);
+		return 0;
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static int gs_usb_get_state(const struct net_device *netdev,
+	enum can_state *state)
+{
+
+	struct gs_can *dev = netdev_priv(netdev);
+	struct usb_interface *intf = dev->iface;
+	int rc;
+	struct gs_device_state *dstate;
+
+	dev_warn(netdev->dev.parent, "CAN state");
+
+	dstate = kmalloc(sizeof(*dstate), GFP_KERNEL);
+	if (!dstate)
+		return -ENOMEM;
+
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_BERR,
+			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			dev->channel,
+			0,
+			dstate,
+			sizeof(*dstate),
+			1000);
+
+	if (rc < 0) {
+		dev_warn(netdev->dev.parent, "Couldn't get state %d", rc);
+		kfree(dstate);
+		return rc;
+	}
+
+	switch (dstate->state) {
+	/* RX/TX error count < 96 */
+	case GS_CAN_STATE_ERROR_ACTIVE:
+		*state = CAN_STATE_ERROR_ACTIVE;
+		break;
+	/* RX/TX error count < 128 */
+	case GS_CAN_STATE_ERROR_WARNING:
+		*state = CAN_STATE_ERROR_WARNING;
+		break;
+	/* RX/TX error count < 256 */
+	case GS_CAN_STATE_ERROR_PASSIVE:
+		*state = CAN_STATE_ERROR_PASSIVE;
+		break;
+	/* RX/TX error count >= 256 */
+	case GS_CAN_STATE_BUS_OFF:
+		*state = CAN_STATE_BUS_OFF;
+		break;
+	/* Device is stopped */
+	case GS_CAN_STATE_STOPPED:
+		*state = CAN_STATE_STOPPED;
+		break;
+	/* Device is sleeping */
+	case GS_CAN_STATE_SLEEPING:
+		*state = CAN_STATE_SLEEPING;
+		break;
+	default:
+		kfree(dstate);
+		return -ENOTSUPP;
+	}
+
+	kfree(dstate);
+	return 0;
+}
+
+static int gs_usb_get_berr_counter(const struct net_device *netdev,
+	struct can_berr_counter *bec)
+{
+	struct gs_can *dev = netdev_priv(netdev);
+	struct usb_interface *intf = dev->iface;
+	int rc;
+	struct gs_device_state *dstate;
+
+	dstate = kmalloc(sizeof(*dstate), GFP_KERNEL);
+	if (!dstate)
+		return -ENOMEM;
+
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_BERR,
+			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			dev->channel,
+			0,
+			dstate,
+			sizeof(*dstate),
+			1000);
+	if (rc < 0) {
+		dev_warn(netdev->dev.parent, "Couldn't get error counters %d",
+			rc);
+		kfree(dstate);
+		return rc;
+	}
+
+	bec->txerr = dstate->txerr;
+	bec->rxerr = dstate->rxerr;
+
+	kfree(dstate);
+	return 0;
+}
+
+static void gs_usb_xmit_callback(struct urb *urb)
+{
+	struct gs_tx_context *txc = urb->context;
+	struct gs_can *dev;
+	struct net_device *netdev;
+
+	dev = txc->dev;
+
+	netdev = dev->netdev;
+
+	if (urb->status) {
+		netdev_info(netdev, "%d] xmit err %d\n",
+			dev->channel, txc->echo_id);
+	}
+
+	usb_free_coherent(urb->dev,
+		urb->transfer_buffer_length,
+		urb->transfer_buffer,
+		urb->transfer_dma);
+
+	atomic_dec(&dev->active_tx_urbs);
+
+	if (!netif_device_present(netdev))
+		return;
+
+	if (netif_queue_stopped(netdev))
+		netif_wake_queue(netdev);
+}
+
+static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
+	struct net_device *netdev)
+{
+	struct gs_can *dev = netdev_priv(netdev);
+	struct net_device_stats *stats = &dev->netdev->stats;
+	struct urb *urb;
+	struct gs_host_frame *hf;
+	struct can_frame *cf;
+	int rc;
+	unsigned int idx;
+	struct gs_tx_context *txc;
+
+	if (dev->can.ctrlmode&CAN_CTRLMODE_LISTENONLY)
+		return NETDEV_TX_BUSY;
+
+	if (can_dropped_invalid_skb(netdev, skb))
+		return NETDEV_TX_OK;
+
+	/* find an empty context to keep track of transmission */
+	txc = gs_alloc_tx_context(dev);
+	if (!txc)
+		return NETDEV_TX_BUSY;
+
+	/* create a URB, and a buffer for it */
+	urb = usb_alloc_urb(0, GFP_ATOMIC);
+	if (!urb) {
+		netdev_err(netdev, "No memory left for URBs\n");
+		goto nomem_urb;
+	}
+
+	hf = usb_alloc_coherent(dev->udev, sizeof(*hf), GFP_ATOMIC,
+		&urb->transfer_dma);
+	if (!hf) {
+		netdev_err(netdev, "No memory left for USB buffer\n");
+		goto nomem_hf;
+	}
+
+	cf = (struct can_frame *)skb->data;
+
+	idx = gs_tx_context_id(txc);
+
+	if (idx >= MAX_TX_URBS) {
+		netdev_err(netdev, "Invalid tx context %d\n", idx);
+		goto badidx;
+	}
+
+	hf->echo_id = idx;
+	hf->channel = dev->channel;
+
+	hf->can_id = cf->can_id;
+	hf->can_dlc = cf->can_dlc;
+	memcpy(hf->data, cf->data, 8);
+
+	usb_fill_bulk_urb(urb, dev->udev,
+			usb_sndbulkpipe(dev->udev, GSUSB_ENDPOINT_OUT),
+			hf,
+			sizeof(*hf),
+			gs_usb_xmit_callback,
+			txc);
+
+	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+	usb_anchor_urb(urb, &dev->tx_submitted);
+
+	can_put_echo_skb(skb, netdev, idx);
+
+	atomic_inc(&dev->active_tx_urbs);
+
+	rc = usb_submit_urb(urb, GFP_ATOMIC);
+	if (unlikely(rc)) {			/* usb send failed */
+		atomic_dec(&dev->active_tx_urbs);
+
+		netdev_err(netdev, "usb_submit failed %d\n", rc);
+
+		can_free_echo_skb(netdev, gs_tx_context_id(txc));
+		gs_free_tx_context(txc);
+
+		usb_unanchor_urb(urb);
+		usb_free_coherent(dev->udev,
+			sizeof(*hf),
+			hf,
+			urb->transfer_dma);
+
+
+
+		if (rc == -ENODEV) {
+			netif_device_detach(netdev);
+		} else {
+			netdev_err(netdev, "Failed tx_urb %d\n", rc);
+
+			stats->tx_dropped++;
+		}
+	} else {
+		netdev->trans_start = jiffies;
+
+		/* Slow down tx path */
+		if (atomic_read(&dev->active_tx_urbs) >= MAX_TX_URBS)
+			netif_stop_queue(netdev);
+	}
+
+	/* let usb core take care of this urb */
+	usb_free_urb(urb);
+
+	return NETDEV_TX_OK;
+
+badidx:
+	usb_free_coherent(dev->udev,
+				sizeof(*hf),
+				hf,
+				urb->transfer_dma);
+nomem_hf:
+	usb_free_urb(urb);
+
+nomem_urb:
+	gs_free_tx_context(txc);
+	dev_kfree_skb(skb);
+	stats->tx_dropped++;
+	return NETDEV_TX_OK;
+}
+
+static int gs_can_open(struct net_device *netdev)
+{
+	struct gs_can *dev = netdev_priv(netdev);
+	struct gs_usb *parent = dev->parent;
+	int rc, i;
+	struct gs_device_mode *dm;
+	u32 ctrlmode;
+
+	/* common open */
+	rc = open_candev(netdev);
+	if (rc)
+		return rc;
+
+	if (atomic_add_return(1, &parent->active_channels) == 1) {
+		for (i = 0; i < MAX_RX_URBS; i++) {
+			struct urb *urb = NULL;
+			u8 *buf = NULL;
+
+			/* alloc rx urb */
+			urb = usb_alloc_urb(0, GFP_KERNEL);
+			if (!urb) {
+				netdev_err(netdev,
+					"No memory left for URBs\n");
+				return -ENOMEM;
+			}
+
+			/* alloc rx buffer */
+			buf = usb_alloc_coherent(dev->udev,
+				sizeof(struct gs_host_frame),
+				GFP_KERNEL,
+				&urb->transfer_dma);
+			if (!buf) {
+				netdev_err(netdev,
+					"No memory left for USB buffer\n");
+				usb_free_urb(urb);
+				return -ENOMEM;
+			}
+
+
+			/* fill, anchor, and submit rx urb */
+			usb_fill_bulk_urb(urb,
+					dev->udev,
+					usb_rcvbulkpipe(dev->udev,
+						GSUSB_ENDPOINT_IN),
+					buf,
+					sizeof(struct gs_host_frame),
+					gs_usb_recieve_bulk_callback,
+					parent
+					);
+			urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+
+			usb_anchor_urb(urb, &parent->rx_submitted);
+
+			rc = usb_submit_urb(urb, GFP_KERNEL);
+			if (rc) {
+				if (rc == -ENODEV)
+					netif_device_detach(dev->netdev);
+
+				usb_unanchor_urb(urb);
+				break;
+			}
+
+			/* Drop reference,
+			 * USB core will take care of freeing it
+			 */
+			usb_free_urb(urb);
+		}
+	}
+
+	dm = kmalloc(sizeof(*dm), GFP_KERNEL);
+	if (!dm)
+		return -ENOMEM;
+
+	/* flags */
+	ctrlmode = dev->can.ctrlmode;
+	dm->flags = 0;
+
+	if (ctrlmode & CAN_CTRLMODE_LOOPBACK)
+		dm->flags |= GS_CAN_MODE_LOOP_BACK;
+
+	else if (ctrlmode & CAN_CTRLMODE_LISTENONLY)
+		dm->flags |= GS_CAN_MODE_LISTEN_ONLY;
+
+
+	/* Controller is not allowed to retry TX
+	 * this mode is unavailable on atmels uc3c hardware
+	 */
+	if (ctrlmode & CAN_CTRLMODE_ONE_SHOT)
+		dm->flags |= GS_CAN_MODE_ONE_SHOT;
+
+	if (ctrlmode & CAN_CTRLMODE_3_SAMPLES)
+		dm->flags |= GS_CAN_MODE_TRIPLE_SAMPLE;
+
+	/* finally start device */
+	dm->mode = GS_CAN_MODE_START;
+	rc = usb_control_msg(interface_to_usbdev(dev->iface),
+			usb_sndctrlpipe(interface_to_usbdev(dev->iface), 0),
+			GS_USB_BREQ_MODE,
+			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			dev->channel,
+			0,
+			dm,
+			sizeof(*dm),
+			1000);
+
+	if (rc < 0) {
+		netdev_err(netdev, "Couldn't start device %d\n", rc);
+		kfree(dm);
+		return rc;
+	}
+
+	/* check mode... */
+	if (!dm)
+		return -ENOMEM;
+
+	rc = usb_control_msg(interface_to_usbdev(dev->iface),
+			usb_rcvctrlpipe(interface_to_usbdev(dev->iface), 0),
+			GS_USB_BREQ_MODE,
+			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			dev->channel,
+			0,
+			dm,
+			sizeof(*dm),
+			1000);
+
+	if (rc < 0) {
+		netdev_err(netdev, "Couldn't get device mode %d\n",
+			rc);
+		kfree(dm);
+		return rc;
+	}
+
+	kfree(dm);
+
+	dev->can.state = CAN_STATE_ERROR_ACTIVE;
+
+	netif_start_queue(netdev);
+
+	netdev_info(netdev, "CAN open\n");
+	return 0;
+}
+
+static int gs_can_close(struct net_device *netdev)
+{
+	int rc;
+	struct gs_can *dev = netdev_priv(netdev);
+	struct gs_usb *parent = dev->parent;
+
+	netif_stop_queue(netdev);
+
+	/* Stop polling */
+	if (atomic_dec_and_test(&parent->active_channels))
+		usb_kill_anchored_urbs(&parent->rx_submitted);
+
+	rc = gs_cmd_reset(parent, dev);
+
+	if (rc < 0)
+		netdev_warn(netdev, "Couldn't shutdown device %d", rc);
+
+	close_candev(netdev);
+
+	return 0;
+}
+
+/******************************** USB ********************************/
+
+static const struct net_device_ops gs_usb_netdev_ops = {
+	.ndo_open = gs_can_open,
+	.ndo_stop = gs_can_close,
+	.ndo_start_xmit = gs_can_start_xmit,
+};
+
+static int gs_make_candev(struct gs_can **out, unsigned int channel,
+	struct usb_interface *intf)
+{
+	struct gs_can *dev;
+	struct net_device *netdev;
+	int rc;
+	struct gs_device_bt_const *bt_const;
+
+	bt_const = kmalloc(sizeof(*bt_const), GFP_KERNEL);
+	if (!bt_const)
+		return -ENOMEM;
+
+	/* fetch bit timing constants */
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_BT_CONST,
+			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			channel,
+			0,
+			bt_const,
+			sizeof(*bt_const),
+			1000);
+
+	if (rc < 0) {
+		dev_err(&intf->dev,
+			"Couldn't get bit timing const for channel %d\n",
+			rc);
+		kfree(bt_const);
+		return rc;
+	}
+
+	/* create netdev */
+	netdev = alloc_candev(sizeof(struct gs_can), MAX_TX_URBS);
+	if (!netdev) {
+		dev_err(&intf->dev, "Couldn't alloc candev\n");
+		kfree(bt_const);
+		return -ENOMEM;
+	}
+
+	dev = netdev_priv(netdev);
+
+	netdev->netdev_ops = &gs_usb_netdev_ops;
+
+	netdev->flags |= IFF_ECHO; /* we support full roundtrip echo */
+
+	/* dev settup */
+	strcpy(dev->bt_const.name, "gs_usb");
+	dev->bt_const.tseg1_min = bt_const->tseg1_min;
+	dev->bt_const.tseg1_max = bt_const->tseg1_max;
+	dev->bt_const.tseg2_min = bt_const->tseg2_min;
+	dev->bt_const.tseg2_max = bt_const->tseg2_max;
+	dev->bt_const.sjw_max = bt_const->sjw_max;
+	dev->bt_const.brp_min = bt_const->brp_min;
+	dev->bt_const.brp_max = bt_const->brp_max;
+	dev->bt_const.brp_inc = bt_const->brp_inc;
+
+	dev->udev = interface_to_usbdev(intf);
+	dev->iface = intf;
+	dev->netdev = netdev;
+	dev->channel = channel;
+
+	init_usb_anchor(&dev->tx_submitted);
+	atomic_set(&dev->active_tx_urbs, 0);
+	spin_lock_init(&dev->tx_ctx_lock);
+	for (rc = 0; rc < MAX_TX_URBS; rc++) {
+		dev->tx_context[rc].dev = dev;
+		dev->tx_context[rc].echo_id = MAX_TX_URBS;
+	}
+
+	/* can settup */
+	dev->can.state = CAN_STATE_STOPPED;
+	dev->can.clock.freq = bt_const->fclk_can;
+	dev->can.bittiming_const = &dev->bt_const;
+	dev->can.do_set_bittiming = gs_usb_set_bittiming;
+	dev->can.do_set_mode = gs_usb_set_mode;
+	dev->can.do_get_state = gs_usb_get_state;
+	dev->can.do_get_berr_counter = gs_usb_get_berr_counter;
+
+	dev->can.ctrlmode_supported = 0;
+
+	if (bt_const->feature & GS_CAN_FEATURE_LISTEN_ONLY)
+		dev->can.ctrlmode_supported |= CAN_CTRLMODE_LISTENONLY;
+
+	if (bt_const->feature & GS_CAN_FEATURE_LOOP_BACK)
+		dev->can.ctrlmode_supported |= CAN_CTRLMODE_LOOPBACK;
+
+	if (bt_const->feature & GS_CAN_FEATURE_TRIPLE_SAMPLE)
+		dev->can.ctrlmode_supported |= CAN_CTRLMODE_3_SAMPLES;
+
+	if (bt_const->feature & GS_CAN_FEATURE_ONE_SHOT)
+		dev->can.ctrlmode_supported |= CAN_CTRLMODE_ONE_SHOT;
+
+	kfree(bt_const);
+
+	SET_NETDEV_DEV(netdev, &intf->dev);
+
+	rc = register_candev(dev->netdev);
+	if (rc) {
+		free_candev(dev->netdev);
+		dev_err(&intf->dev, "Couldn't register candev\n");
+		return rc;
+	}
+
+	*out = dev;
+	return 0;
+}
+
+static void gs_destroy_candev(struct gs_can *dev)
+{
+	unregister_candev(dev->netdev);
+	free_candev(dev->netdev);
+	usb_kill_anchored_urbs(&dev->tx_submitted);
+}
+
+static int gs_usb_probe(struct usb_interface *intf,
+	const struct usb_device_id *id)
+{
+	struct gs_usb *dev;
+	int rc = -ENOMEM;
+	unsigned int icount, i;
+	struct gs_host_config *hconf;
+	struct gs_device_config *dconf;
+
+	hconf = kmalloc(sizeof(*hconf), GFP_KERNEL);
+	if (!hconf)
+		return -ENOMEM;
+
+	hconf->byte_order = 0x0000beef;
+
+
+	/* send host config */
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_HOST_FORMAT,
+			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			1,
+			intf->altsetting[0].desc.bInterfaceNumber,
+			hconf,
+			sizeof(*hconf),
+			1000);
+
+	kfree(hconf);
+
+	if (rc < 0) {
+		dev_err(&intf->dev, "Couldn't send data format: %d\n",
+			rc);
+		return rc;
+	}
+
+
+	dconf = kmalloc(sizeof(*dconf), GFP_KERNEL);
+	if (!dconf)
+		return -ENOMEM;
+
+	/* read device config */
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_DEVICE_CONFIG,
+			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			1,
+			intf->altsetting[0].desc.bInterfaceNumber,
+			dconf,
+			sizeof(*dconf),
+			1000);
+	if (rc < 0) {
+		dev_err(&intf->dev, "Couldn't recieve device config: %d\n",
+			rc);
+
+		kfree(dconf);
+
+		return rc;
+	}
+
+	icount = dconf->icount+1;
+
+	kfree(dconf);
+
+	dev_info(&intf->dev, "Configuring for %d interfaces\n", icount);
+
+	if (icount > MAX_INTF) {
+		dev_err(&intf->dev,
+			"Driver cannot handle more that %d Can interfaces\n",
+			MAX_INTF);
+		return -EINVAL;
+	}
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	init_usb_anchor(&dev->rx_submitted);
+
+	atomic_set(&dev->active_channels, 0);
+
+	usb_set_intfdata(intf, dev);
+
+	for (i = 0; i < icount; i++) {
+		rc = gs_make_candev(&dev->canch[i], i, intf);
+		if (rc) {
+			/* on failure destroy previously created candevs */
+			icount = i;
+			for (i = 0; i < icount; i++) {
+				gs_destroy_candev(dev->canch[i]);
+				dev->canch[icount] = NULL;
+			}
+			return rc;
+		}
+		dev->canch[i]->parent = dev;
+	}
+
+	dev_info(&intf->dev, "Probe\n");
+	return 0;
+}
+
+static void gs_usb_disconnect(struct usb_interface *intf)
+{
+	unsigned i;
+	struct gs_usb *dev = usb_get_intfdata(intf);
+	usb_set_intfdata(intf, NULL);
+
+	if (!dev) {
+		dev_err(&intf->dev, "Disconnect (nodata)\n");
+		return;
+	}
+
+	for (i = 0; i < MAX_INTF; i++) {
+		struct gs_can *can = dev->canch[i];
+
+		if (!can)
+			continue;
+
+		gs_destroy_candev(can);
+	}
+
+	usb_kill_anchored_urbs(&dev->rx_submitted);
+}
+
+MODULE_DEVICE_TABLE(usb, gs_usb_table);
+
+static struct usb_device_id gs_usb_table[] = {
+	{USB_DEVICE(USB_GSUSB_1_VENDOR_ID, USB_GSUSB_1_PRODUCT_ID)},
+	{} /* Terminating entry */
+};
+
+static struct usb_driver gs_usb_driver = {
+	.name       = "gs_usb",
+	.probe      = gs_usb_probe,
+	.disconnect = gs_usb_disconnect,
+	.id_table   = gs_usb_table
+};
+
+static int __init gs_usb_init(void)
+{
+	return usb_register(&gs_usb_driver);
+}
+
+static void __exit gs_usb_exit(void)
+{
+	usb_deregister(&gs_usb_driver);
+}
+
+module_init(gs_usb_init);
+module_exit(gs_usb_exit);
+
+MODULE_AUTHOR("Maximilian Schneider <mws@schneidersoft.net>");
+MODULE_DESCRIPTION(
+"Socket CAN device driver for Geschwister Schneider Technologie-, "
+"Entwicklungs- und Vertriebs UG. USB2.0 to CAN interfaces.");
+MODULE_LICENSE("GPL v2");
+
-- 
1.7.10.4

Re: GS_USB

[Wolfgang Grandegger]

On Mon, 07 Oct 2013 14:22:00 +0000, "Max S." <max@schneidersoft.net>

wrote:

> Hello Wolfgang,

> 

> Here is the cleaned up patch incorporating your suggestions.

> 

> I am using "git commit --amend" to compile changes into a single patch.

> Is this the correct method?



I normally use "git rebase -i <first-commit-id>"? It's very

powerful and allows to reorder, squash, re-word commits and

much more.



Will not find time for the review today...



The CAN controller does not do any asynchronous error reporting,

right? This will limit the usability of this device, especially

CAN applications relying on that feature will not work. Any chance

to add asynchronous error reporting to the firmware?



Wolfgang.

Re: GS_USB

[Max S.]

On Mon, 2013-10-07 at 16:37 +0200, Wolfgang Grandegger wrote:
> Will not find time for the review today...

no problem.

> The CAN controller does not do any asynchronous error reporting,
> right? This will limit the usability of this device, especially
> CAN applications relying on that feature will not work. Any chance
> to add asynchronous error reporting to the firmware?

Only CAN_ERR_CRTL_RX_OVERFLOW is currently reported (possible when host
is too slow).
CAN_ERR_CRTL_TX_OVERFLOW is impossible due to the driver design
(tx context + echo).

Which errors are most important to the applications you mentioned?

The hardware does not allow for the sensing of the CAN_ERR_TRX_* errors.
I can sense some  CAN_ERR_PROT_* errors, as well as all CAN_ERR_CRTL_*
errors.

In firmware it is possible to queue error/status frames much like normal
frames. So they would show up in the receive callback... Thats what you
meant by asynchronous right?

regards,
Max Schneider.

Re: GS_USB

[Wolfgang Grandegger]

On 10/07/2013 09:52 PM, Max S. wrote:
> On Mon, 2013-10-07 at 16:37 +0200, Wolfgang Grandegger wrote:
>> Will not find time for the review today...
> 
> no problem.
> 
>> The CAN controller does not do any asynchronous error reporting,
>> right? This will limit the usability of this device, especially
>> CAN applications relying on that feature will not work. Any chance
>> to add asynchronous error reporting to the firmware?
> 
> Only CAN_ERR_CRTL_RX_OVERFLOW is currently reported (possible when host
> is too slow).
> CAN_ERR_CRTL_TX_OVERFLOW is impossible due to the driver design
> (tx context + echo).
> 
> Which errors are most important to the applications you mentioned?

CAN error state changes are sufficient, including bus-off. Bus-off
recovery initiated by the software would be nice as well. Reporting
individual bus errors is less important.

> The hardware does not allow for the sensing of the CAN_ERR_TRX_* errors.
> I can sense some  CAN_ERR_PROT_* errors, as well as all CAN_ERR_CRTL_*
> errors.

> In firmware it is possible to queue error/status frames much like normal
> frames. So they would show up in the receive callback... Thats what you
> meant by asynchronous right?

Yep, an application can then read and handle these error messages. Here
is the output of "candump -candump -td -e any,0:0,#FFFFFFFF" showing
error state changes until bus-off and recovery with an SJA1000:

 (000.202225)  can0   5F  [8] 07 B4 4F 67 3A 90 D9 E4
 (000.201285)  can0  20000204  [8] 00 08 00 00 00 00 78 00   ERRORFRAME
        controller-problem{tx-error-warning}
        error-counter-tx-rx{{120}{0}}
 (000.003249)  can0  20000240  [8] 00 00 00 00 00 00 00 00   ERRORFRAME
        bus-off
 (005.015531)  can0  20000100  [8] 00 00 00 00 00 00 7F 00   ERRORFRAME
        restarted-after-bus-off
        error-counter-tx-rx{{127}{0}}

We don't have yet support for decreasing the error state, e.g.:

 (000.000133)  can0  20000200  [8] 00 40 00 00 00 00 00 00   ERRORFRAME
        state-change{back-to-error-active}


Wolfgang.

GS_USB

[Max S.]

Any progress on reviewing the GS_USB driver code?

I have added asynchronous state update. Here is the latest patch.


From 346f223bb3a8f4435f93cdfbc5e06db2cbf7179d Mon Sep 17 00:00:00 2001
From: Maximilian Schneider <max@schneidersoft.net>
Date: Sun, 3 Nov 2013 16:57:06 +0000
Subject: [PATCH] Added support for the GS_USB CAN devices.


Signed-off-by: Maximilian Schneider <max@schneidersoft.net>
---
 drivers/net/can/usb/Kconfig  |    8 +
 drivers/net/can/usb/Makefile |    1 +
 drivers/net/can/usb/gs_usb.c | 1037
++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 1046 insertions(+)
 create mode 100644 drivers/net/can/usb/gs_usb.c

diff --git a/drivers/net/can/usb/Kconfig b/drivers/net/can/usb/Kconfig
index fc96a3d..f5e3e8c 100644
--- a/drivers/net/can/usb/Kconfig
+++ b/drivers/net/can/usb/Kconfig
@@ -54,4 +54,12 @@ config CAN_8DEV_USB
 	  This driver supports the USB2CAN interface
 	  from 8 devices (http://www.8devices.com).
 
+config CAN_GS_USB
+	tristate "Geschwister Schneider UG interfaces"
+	---help---
+	  This driver supports the Geschwister Schneider USB/CAN devices.
+	  If unsure choose N,
+	  choose Y for built in support,
+	  M to compile as module (module will be named: gs_usb).
+
 endmenu
diff --git a/drivers/net/can/usb/Makefile b/drivers/net/can/usb/Makefile
index becef46..c21a521 100644
--- a/drivers/net/can/usb/Makefile
+++ b/drivers/net/can/usb/Makefile
@@ -7,5 +7,6 @@ obj-$(CONFIG_CAN_ESD_USB2) += esd_usb2.o
 obj-$(CONFIG_CAN_KVASER_USB) += kvaser_usb.o
 obj-$(CONFIG_CAN_PEAK_USB) += peak_usb/
 obj-$(CONFIG_CAN_8DEV_USB) += usb_8dev.o
+obj-$(CONFIG_CAN_GS_USB) += gs_usb.o
 
 ccflags-$(CONFIG_CAN_DEBUG_DEVICES) := -DDEBUG
diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
new file mode 100644
index 0000000..4aa28c0
--- /dev/null
+++ b/drivers/net/can/usb/gs_usb.c
@@ -0,0 +1,1037 @@
+/* CAN driver for Geschwister Schneider USB/CAN devices.
+ *
+ * Copyright (C) 2013 Geschwister Schneider Technologie-,
+ * Entwicklungs- und Vertriebs UG (Haftungsbeschränkt).
+ *
+ * Many thanks to all socketcan devs!
+ *
+ * This program is free software; you can redistribute it and/or modify
it
+ * under the terms of the GNU General Public License as published
+ * by the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/init.h>
+#include <linux/signal.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/usb.h>
+
+#include <linux/can.h>
+#include <linux/can/dev.h>
+#include <linux/can/error.h>
+
+/* Device specific constants */
+#define USB_GSUSB_1_VENDOR_ID      0x1d50
+#define USB_GSUSB_1_PRODUCT_ID     0x606f
+
+#define GSUSB_ENDPOINT_IN          1
+#define GSUSB_ENDPOINT_OUT         2
+
+/* Device specific constants */
+enum gs_usb_breq {
+	GS_USB_BREQ_HOST_FORMAT = 0,
+	GS_USB_BREQ_BITTIMING,
+	GS_USB_BREQ_MODE,
+	GS_USB_BREQ_BERR,
+	GS_USB_BREQ_BT_CONST,
+	GS_USB_BREQ_DEVICE_CONFIG
+};
+
+enum gs_can_mode {
+	GS_CAN_MODE_RESET = 0,
+	GS_CAN_MODE_START
+};
+
+enum gs_can_state {
+	GS_CAN_STATE_ERROR_ACTIVE = 0,
+	GS_CAN_STATE_ERROR_WARNING,
+	GS_CAN_STATE_ERROR_PASSIVE,
+	GS_CAN_STATE_BUS_OFF,
+	GS_CAN_STATE_STOPPED,
+	GS_CAN_STATE_SLEEPING
+};
+
+/* data types passed between host and device */
+struct __packed gs_host_config {
+	u32 byte_order;
+};
+
+struct __packed gs_device_config {
+	u8 reserved1;
+	u8 reserved2;
+	u8 reserved3;
+	u8 icount;
+	u32 sw_version;
+	u32 hw_version;
+};
+
+#define GS_CAN_MODE_NORMAL               0
+#define GS_CAN_MODE_LISTEN_ONLY          (1<<0)
+#define GS_CAN_MODE_LOOP_BACK            (1<<1)
+#define GS_CAN_MODE_TRIPLE_SAMPLE        (1<<2)
+#define GS_CAN_MODE_ONE_SHOT             (1<<3)
+
+struct __packed gs_device_mode {
+	u32 mode;
+	u32 flags;
+};
+
+struct __packed gs_device_state {
+	u32 state;
+	u32 rxerr;
+	u32 txerr;
+};
+
+struct __packed gs_device_bittiming {
+	u32 prop_seg;
+	u32 phase_seg1;
+	u32 phase_seg2;
+	u32 sjw;
+	u32 brp;
+};
+
+#define GS_CAN_FEATURE_LISTEN_ONLY      (1<<0)
+#define GS_CAN_FEATURE_LOOP_BACK        (1<<1)
+#define GS_CAN_FEATURE_TRIPLE_SAMPLE    (1<<2)
+#define GS_CAN_FEATURE_ONE_SHOT         (1<<3)
+
+struct __packed gs_device_bt_const {
+	u32 feature;
+	u32 fclk_can;
+	u32 tseg1_min;
+	u32 tseg1_max;
+	u32 tseg2_min;
+	u32 tseg2_max;
+	u32 sjw_max;
+	u32 brp_min;
+	u32 brp_max;
+	u32 brp_inc;
+};
+
+#define GS_CAN_FLAG_OVERFLOW 1
+
+struct __packed gs_host_frame {
+	u32 echo_id;
+	u32 can_id;
+
+	u8 can_dlc;
+	u8 channel;
+	u8 flags;
+	u8 reserved;
+
+	u8 data[8];
+};
+
+/* Special address description flags for the CAN_ID */
+#define GS_EFF_FLAG 0x80000000U /* EFF/SFF is set in the MSB */
+#define GS_RTR_FLAG 0x40000000U /* remote transmission request */
+#define GS_ERR_FLAG 0x20000000U /* error frame */
+
+/* Valid bits in CAN ID for frame formats */
+#define GS_SFF_MASK 0x000007FFU /* standard frame format (SFF) */
+#define GS_EFF_MASK 0x1FFFFFFFU /* extended frame format (EFF) */
+#define GS_ERR_MASK 0x1FFFFFFFU /* omit EFF, RTR, ERR flags */
+
+/* Only send a max of MAX_TX_URBS frames per channel to the device at a
time. */
+#define MAX_TX_URBS 10
+/* Only launch a max of MAX_RX_URBS usb requests at a time. */
+#define MAX_RX_URBS 30
+/* Maximum number of interfaces the driver supports per device.
+ * Current hardware only supports 2 interfaces. The future may vary.
+ */
+#define MAX_INTF 2
+
+struct gs_tx_context {
+	struct gs_can *dev;
+	unsigned int echo_id;
+};
+
+struct gs_can {
+	struct can_priv can; /* must be the first member */
+
+	struct gs_usb *parent;
+
+	struct net_device *netdev;
+	struct usb_device *udev;
+	struct usb_interface *iface;
+
+	struct can_bittiming_const bt_const;
+	unsigned int channel;	/* channel number */
+
+	/* This lock prevents a race condition
+	 * between xmit and recieve.
+	 */
+	spinlock_t tx_ctx_lock;
+	struct gs_tx_context tx_context[MAX_TX_URBS];
+
+	struct usb_anchor tx_submitted;
+	atomic_t active_tx_urbs;
+};
+
+/* usb interface struct */
+struct gs_usb {
+	struct gs_can *canch[MAX_INTF];
+
+	struct usb_anchor rx_submitted;
+
+	atomic_t active_channels;
+};
+
+/* 'allocate' a tx context.
+ * returns a valid tx context or NULL if there is no space.
+ */
+static struct gs_tx_context *gs_alloc_tx_context(struct gs_can *dev)
+{
+	int i = 0;
+
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->tx_ctx_lock, flags);
+
+	for (; i < MAX_TX_URBS; i++) {
+		if (dev->tx_context[i].echo_id == MAX_TX_URBS) {
+			dev->tx_context[i].echo_id = i;
+			spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
+			return &dev->tx_context[i];
+		}
+	}
+
+	spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
+	return NULL;
+}
+
+/* releases a tx context
+ */
+static void gs_free_tx_context(struct gs_tx_context *txc)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&txc->dev->tx_ctx_lock, flags);
+	txc->echo_id = MAX_TX_URBS;
+	spin_unlock_irqrestore(&txc->dev->tx_ctx_lock, flags);
+}
+
+/* Get a tx context by id.
+ */
+static struct gs_tx_context *gs_get_tx_context(
+	struct gs_can *dev,
+	unsigned int id)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->tx_ctx_lock, flags);
+	if (id < MAX_TX_URBS) {
+		if (dev->tx_context[id].echo_id == id) {
+			spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
+			return &dev->tx_context[id];
+		}
+	}
+	spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
+	return NULL;
+}
+
+/* Get a tx contexts id.
+ */
+static unsigned int gs_tx_context_id(struct gs_tx_context *txc)
+{
+	unsigned int id;
+
+	unsigned long flags;
+
+	spin_lock_irqsave(&txc->dev->tx_ctx_lock, flags);
+	id = txc->echo_id;
+	spin_unlock_irqrestore(&txc->dev->tx_ctx_lock, flags);
+	return id;
+}
+
+static int gs_cmd_reset(struct gs_usb *gsusb, struct gs_can *gsdev)
+{
+	struct gs_device_mode *dm;
+	struct usb_interface *intf = gsdev->iface;
+	int rc;
+
+	dm = kzalloc(sizeof(*dm), GFP_KERNEL);
+	if (!dm)
+		return -ENOMEM;
+
+	dm->mode = GS_CAN_MODE_RESET;
+
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_MODE,
+			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			gsdev->channel,
+			0,
+			dm,
+			sizeof(*dm),
+			1000);
+
+	return rc;
+}
+
+static void gs_update_state(struct gs_can *dev, struct can_frame *cf)
+{
+	if (cf->can_id & CAN_ERR_BUSOFF) {
+		dev->can.state = CAN_STATE_BUS_OFF;
+	} else if (cf->can_id & CAN_ERR_CRTL) {
+		dev->can.state = CAN_STATE_ERROR_ACTIVE;
+
+		if ((cf->data[1] & CAN_ERR_CRTL_TX_WARNING) ||
+			(cf->data[1] & CAN_ERR_CRTL_RX_WARNING))
+			dev->can.state = CAN_STATE_ERROR_WARNING;
+
+		if ((cf->data[1] & CAN_ERR_CRTL_TX_PASSIVE) ||
+			(cf->data[1]&CAN_ERR_CRTL_RX_PASSIVE))
+			dev->can.state = CAN_STATE_ERROR_PASSIVE;
+	}
+}
+
+/**************************** USB CALLBACKS **************************/
+static void gs_usb_recieve_bulk_callback(struct urb *urb)
+{
+	struct gs_usb *usbcan = urb->context;
+	struct gs_can *dev;
+	struct net_device *netdev;
+	int rc;
+	struct net_device_stats *stats;
+	struct gs_host_frame *hf = urb->transfer_buffer;
+	struct gs_tx_context *txc;
+
+	struct can_frame *cf;
+	struct sk_buff *skb;
+
+	BUG_ON(!usbcan);
+
+	switch (urb->status) {
+	case 0: /* success */
+		break;
+	case -ENOENT:
+	case -ESHUTDOWN:
+		return;
+	default:
+		/* do not resubmit aborted urbs. eg: when device goes down */
+		return;
+	}
+
+	/* device reports out of range channel id */
+	if (hf->channel >= MAX_INTF)
+		goto resubmit_urb;
+
+	/* device reports bad channel id */
+	dev = usbcan->canch[hf->channel];
+
+	netdev = dev->netdev;
+
+	if (!netif_device_present(netdev))
+		return;
+
+	stats = &dev->netdev->stats;
+
+	if (hf->echo_id == -1) { /* normal rx */
+		skb = alloc_can_skb(dev->netdev, &cf);
+		if (skb == NULL)
+			return;
+
+		cf->can_id = hf->can_id;
+		/* is it necessary to use get_can_dlc? */
+		cf->can_dlc = get_can_dlc(hf->can_dlc);
+		memcpy(cf->data, hf->data, 8);
+
+		/* ERROR frames tell us information about the controler */
+		if (hf->can_id & GS_ERR_FLAG)
+			gs_update_state(dev, cf);
+
+		netif_rx(skb);
+
+		netdev->stats.rx_packets++;
+		netdev->stats.rx_bytes += hf->can_dlc;
+	} else { /* echo_id == hf->echo_id */
+		if (hf->echo_id >= MAX_TX_URBS) {
+			netdev_err(netdev,
+				"Device sent an out of range echo id:%d\n",
+				hf->echo_id);
+			goto resubmit_urb;
+		}
+
+		netdev->stats.tx_packets++;
+		netdev->stats.tx_bytes += hf->can_dlc;
+
+		txc = gs_get_tx_context(dev, hf->echo_id);
+
+		/* bad devices send bad echo_ids. */
+		if (!txc) {
+			netdev_err(netdev,
+				"Device sent a bad echo id:%d\n",
+				hf->echo_id);
+			goto resubmit_urb;
+		}
+
+		can_get_echo_skb(netdev, gs_tx_context_id(txc));
+
+		gs_free_tx_context(txc);
+
+		netif_wake_queue(netdev);
+	}
+
+	if (hf->flags & GS_CAN_FLAG_OVERFLOW) {
+		skb = alloc_can_err_skb(netdev, &cf);
+		if (skb == NULL)
+			goto resubmit_urb;
+
+		cf->can_id |= CAN_ERR_CRTL;
+		cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
+		stats->rx_over_errors++;
+		stats->rx_errors++;
+		netif_rx(skb);
+	}
+
+
+resubmit_urb:
+	/* note: no urb refill... works for me */
+
+	rc = usb_submit_urb(urb, GFP_ATOMIC);
+
+	/* USB failure take down all interfaces */
+	if (rc == -ENODEV) {
+		for (rc = 0; rc < MAX_INTF; rc++) {
+			if (usbcan->canch[rc])
+				netif_device_detach(usbcan->canch[rc]->netdev);
+		}
+	}
+}
+
+static int gs_usb_set_bittiming(struct net_device *netdev)
+{
+	struct gs_can *dev = netdev_priv(netdev);
+	struct can_bittiming *bt = &dev->can.bittiming;
+	struct usb_interface *intf = dev->iface;
+	int rc;
+	struct gs_device_bittiming *dbt;
+
+	dbt = kmalloc(sizeof(*dbt), GFP_KERNEL);
+	if (!dbt)
+		return -ENOMEM;
+
+	dbt->prop_seg = bt->prop_seg;
+	dbt->phase_seg1 = bt->phase_seg1;
+	dbt->phase_seg2 = bt->phase_seg2;
+	dbt->sjw = bt->sjw;
+	dbt->brp = bt->brp;
+
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_BITTIMING,
+			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			dev->channel,
+			0,
+			dbt,
+			sizeof(*dbt),
+			1000);
+	if (rc < 0)
+		dev_err(netdev->dev.parent, "Couldn't set bittimings %d", rc);
+
+	kfree(dbt);
+
+	return rc;
+}
+
+static int gs_usb_set_mode(struct net_device *netdev, enum can_mode
mode)
+{
+	if (mode == CAN_MODE_START) {
+		netif_wake_queue(netdev);
+		return 0;
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static void gs_usb_xmit_callback(struct urb *urb)
+{
+	struct gs_tx_context *txc = urb->context;
+	struct gs_can *dev;
+	struct net_device *netdev;
+
+	dev = txc->dev;
+
+	netdev = dev->netdev;
+
+	if (urb->status) {
+		netdev_info(netdev, "%d] xmit err %d\n",
+			dev->channel, txc->echo_id);
+	}
+
+	usb_free_coherent(urb->dev,
+		urb->transfer_buffer_length,
+		urb->transfer_buffer,
+		urb->transfer_dma);
+
+	atomic_dec(&dev->active_tx_urbs);
+
+	if (!netif_device_present(netdev))
+		return;
+
+	if (netif_queue_stopped(netdev))
+		netif_wake_queue(netdev);
+}
+
+static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
+	struct net_device *netdev)
+{
+	struct gs_can *dev = netdev_priv(netdev);
+	struct net_device_stats *stats = &dev->netdev->stats;
+	struct urb *urb;
+	struct gs_host_frame *hf;
+	struct can_frame *cf;
+	int rc;
+	unsigned int idx;
+	struct gs_tx_context *txc;
+
+	if (dev->can.ctrlmode&CAN_CTRLMODE_LISTENONLY)
+		return NETDEV_TX_BUSY;
+
+	if (can_dropped_invalid_skb(netdev, skb))
+		return NETDEV_TX_OK;
+
+	/* find an empty context to keep track of transmission */
+	txc = gs_alloc_tx_context(dev);
+	if (!txc)
+		return NETDEV_TX_BUSY;
+
+	/* create a URB, and a buffer for it */
+	urb = usb_alloc_urb(0, GFP_ATOMIC);
+	if (!urb) {
+		netdev_err(netdev, "No memory left for URBs\n");
+		goto nomem_urb;
+	}
+
+	hf = usb_alloc_coherent(dev->udev, sizeof(*hf), GFP_ATOMIC,
+		&urb->transfer_dma);
+	if (!hf) {
+		netdev_err(netdev, "No memory left for USB buffer\n");
+		goto nomem_hf;
+	}
+
+	cf = (struct can_frame *)skb->data;
+
+	idx = gs_tx_context_id(txc);
+
+	if (idx >= MAX_TX_URBS) {
+		netdev_err(netdev, "Invalid tx context %d\n", idx);
+		goto badidx;
+	}
+
+	hf->echo_id = idx;
+	hf->channel = dev->channel;
+
+	hf->can_id = cf->can_id;
+	hf->can_dlc = cf->can_dlc;
+	memcpy(hf->data, cf->data, 8);
+
+	usb_fill_bulk_urb(urb, dev->udev,
+			usb_sndbulkpipe(dev->udev, GSUSB_ENDPOINT_OUT),
+			hf,
+			sizeof(*hf),
+			gs_usb_xmit_callback,
+			txc);
+
+	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+	usb_anchor_urb(urb, &dev->tx_submitted);
+
+	can_put_echo_skb(skb, netdev, idx);
+
+	atomic_inc(&dev->active_tx_urbs);
+
+	rc = usb_submit_urb(urb, GFP_ATOMIC);
+	if (unlikely(rc)) {			/* usb send failed */
+		atomic_dec(&dev->active_tx_urbs);
+
+		netdev_err(netdev, "usb_submit failed %d\n", rc);
+
+		can_free_echo_skb(netdev, gs_tx_context_id(txc));
+		gs_free_tx_context(txc);
+
+		usb_unanchor_urb(urb);
+		usb_free_coherent(dev->udev,
+			sizeof(*hf),
+			hf,
+			urb->transfer_dma);
+
+
+
+		if (rc == -ENODEV) {
+			netif_device_detach(netdev);
+		} else {
+			netdev_err(netdev, "Failed tx_urb %d\n", rc);
+
+			stats->tx_dropped++;
+		}
+	} else {
+		netdev->trans_start = jiffies;
+
+		/* Slow down tx path */
+		if (atomic_read(&dev->active_tx_urbs) >= MAX_TX_URBS)
+			netif_stop_queue(netdev);
+	}
+
+	/* let usb core take care of this urb */
+	usb_free_urb(urb);
+
+	return NETDEV_TX_OK;
+
+badidx:
+	usb_free_coherent(dev->udev,
+				sizeof(*hf),
+				hf,
+				urb->transfer_dma);
+nomem_hf:
+	usb_free_urb(urb);
+
+nomem_urb:
+	gs_free_tx_context(txc);
+	dev_kfree_skb(skb);
+	stats->tx_dropped++;
+	return NETDEV_TX_OK;
+}
+
+static int gs_can_open(struct net_device *netdev)
+{
+	struct gs_can *dev = netdev_priv(netdev);
+	struct gs_usb *parent = dev->parent;
+	int rc, i;
+	struct gs_device_mode *dm;
+	u32 ctrlmode;
+
+	/* common open */
+	rc = open_candev(netdev);
+	if (rc)
+		return rc;
+
+	if (atomic_add_return(1, &parent->active_channels) == 1) {
+		for (i = 0; i < MAX_RX_URBS; i++) {
+			struct urb *urb = NULL;
+			u8 *buf = NULL;
+
+			/* alloc rx urb */
+			urb = usb_alloc_urb(0, GFP_KERNEL);
+			if (!urb) {
+				netdev_err(netdev,
+					"No memory left for URBs\n");
+				return -ENOMEM;
+			}
+
+			/* alloc rx buffer */
+			buf = usb_alloc_coherent(dev->udev,
+				sizeof(struct gs_host_frame),
+				GFP_KERNEL,
+				&urb->transfer_dma);
+			if (!buf) {
+				netdev_err(netdev,
+					"No memory left for USB buffer\n");
+				usb_free_urb(urb);
+				return -ENOMEM;
+			}
+
+
+			/* fill, anchor, and submit rx urb */
+			usb_fill_bulk_urb(urb,
+					dev->udev,
+					usb_rcvbulkpipe(dev->udev,
+						GSUSB_ENDPOINT_IN),
+					buf,
+					sizeof(struct gs_host_frame),
+					gs_usb_recieve_bulk_callback,
+					parent
+					);
+			urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+
+			usb_anchor_urb(urb, &parent->rx_submitted);
+
+			rc = usb_submit_urb(urb, GFP_KERNEL);
+			if (rc) {
+				if (rc == -ENODEV)
+					netif_device_detach(dev->netdev);
+
+				usb_unanchor_urb(urb);
+				break;
+			}
+
+			/* Drop reference,
+			 * USB core will take care of freeing it
+			 */
+			usb_free_urb(urb);
+		}
+	}
+
+	dm = kmalloc(sizeof(*dm), GFP_KERNEL);
+	if (!dm)
+		return -ENOMEM;
+
+	/* flags */
+	ctrlmode = dev->can.ctrlmode;
+	dm->flags = 0;
+
+	if (ctrlmode & CAN_CTRLMODE_LOOPBACK)
+		dm->flags |= GS_CAN_MODE_LOOP_BACK;
+
+	else if (ctrlmode & CAN_CTRLMODE_LISTENONLY)
+		dm->flags |= GS_CAN_MODE_LISTEN_ONLY;
+
+
+	/* Controller is not allowed to retry TX
+	 * this mode is unavailable on atmels uc3c hardware
+	 */
+	if (ctrlmode & CAN_CTRLMODE_ONE_SHOT)
+		dm->flags |= GS_CAN_MODE_ONE_SHOT;
+
+	if (ctrlmode & CAN_CTRLMODE_3_SAMPLES)
+		dm->flags |= GS_CAN_MODE_TRIPLE_SAMPLE;
+
+	/* finally start device */
+	dm->mode = GS_CAN_MODE_START;
+	rc = usb_control_msg(interface_to_usbdev(dev->iface),
+			usb_sndctrlpipe(interface_to_usbdev(dev->iface), 0),
+			GS_USB_BREQ_MODE,
+			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			dev->channel,
+			0,
+			dm,
+			sizeof(*dm),
+			1000);
+
+	if (rc < 0) {
+		netdev_err(netdev, "Couldn't start device %d\n", rc);
+		kfree(dm);
+		return rc;
+	}
+
+	/* check mode... */
+	if (!dm)
+		return -ENOMEM;
+
+	rc = usb_control_msg(interface_to_usbdev(dev->iface),
+			usb_rcvctrlpipe(interface_to_usbdev(dev->iface), 0),
+			GS_USB_BREQ_MODE,
+			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			dev->channel,
+			0,
+			dm,
+			sizeof(*dm),
+			1000);
+
+	if (rc < 0) {
+		netdev_err(netdev, "Couldn't get device mode %d\n",
+			rc);
+		kfree(dm);
+		return rc;
+	}
+
+	kfree(dm);
+
+	dev->can.state = CAN_STATE_ERROR_ACTIVE;
+
+	netif_start_queue(netdev);
+
+	netdev_info(netdev, "CAN open\n");
+	return 0;
+}
+
+static int gs_can_close(struct net_device *netdev)
+{
+	int rc;
+	struct gs_can *dev = netdev_priv(netdev);
+	struct gs_usb *parent = dev->parent;
+
+	netif_stop_queue(netdev);
+
+	/* Stop polling */
+	if (atomic_dec_and_test(&parent->active_channels))
+		usb_kill_anchored_urbs(&parent->rx_submitted);
+
+	rc = gs_cmd_reset(parent, dev);
+
+	if (rc < 0)
+		netdev_warn(netdev, "Couldn't shutdown device %d", rc);
+
+	close_candev(netdev);
+
+	return 0;
+}
+
+/******************************** USB ********************************/
+
+static const struct net_device_ops gs_usb_netdev_ops = {
+	.ndo_open = gs_can_open,
+	.ndo_stop = gs_can_close,
+	.ndo_start_xmit = gs_can_start_xmit,
+};
+
+static int gs_make_candev(struct gs_can **out, unsigned int channel,
+	struct usb_interface *intf)
+{
+	struct gs_can *dev;
+	struct net_device *netdev;
+	int rc;
+	struct gs_device_bt_const *bt_const;
+
+	bt_const = kmalloc(sizeof(*bt_const), GFP_KERNEL);
+	if (!bt_const)
+		return -ENOMEM;
+
+	/* fetch bit timing constants */
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_BT_CONST,
+			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			channel,
+			0,
+			bt_const,
+			sizeof(*bt_const),
+			1000);
+
+	if (rc < 0) {
+		dev_err(&intf->dev,
+			"Couldn't get bit timing const for channel %d\n",
+			rc);
+		kfree(bt_const);
+		return rc;
+	}
+
+	/* create netdev */
+	netdev = alloc_candev(sizeof(struct gs_can), MAX_TX_URBS);
+	if (!netdev) {
+		dev_err(&intf->dev, "Couldn't alloc candev\n");
+		kfree(bt_const);
+		return -ENOMEM;
+	}
+
+	dev = netdev_priv(netdev);
+
+	netdev->netdev_ops = &gs_usb_netdev_ops;
+
+	netdev->flags |= IFF_ECHO; /* we support full roundtrip echo */
+
+	/* dev settup */
+	strcpy(dev->bt_const.name, "gs_usb");
+	dev->bt_const.tseg1_min = bt_const->tseg1_min;
+	dev->bt_const.tseg1_max = bt_const->tseg1_max;
+	dev->bt_const.tseg2_min = bt_const->tseg2_min;
+	dev->bt_const.tseg2_max = bt_const->tseg2_max;
+	dev->bt_const.sjw_max = bt_const->sjw_max;
+	dev->bt_const.brp_min = bt_const->brp_min;
+	dev->bt_const.brp_max = bt_const->brp_max;
+	dev->bt_const.brp_inc = bt_const->brp_inc;
+
+	dev->udev = interface_to_usbdev(intf);
+	dev->iface = intf;
+	dev->netdev = netdev;
+	dev->channel = channel;
+
+	init_usb_anchor(&dev->tx_submitted);
+	atomic_set(&dev->active_tx_urbs, 0);
+	spin_lock_init(&dev->tx_ctx_lock);
+	for (rc = 0; rc < MAX_TX_URBS; rc++) {
+		dev->tx_context[rc].dev = dev;
+		dev->tx_context[rc].echo_id = MAX_TX_URBS;
+	}
+
+	/* can settup */
+	dev->can.state = CAN_STATE_STOPPED;
+	dev->can.clock.freq = bt_const->fclk_can;
+	dev->can.bittiming_const = &dev->bt_const;
+	dev->can.do_set_bittiming = gs_usb_set_bittiming;
+	dev->can.do_set_mode = gs_usb_set_mode;
+
+	dev->can.ctrlmode_supported = 0;
+
+	if (bt_const->feature & GS_CAN_FEATURE_LISTEN_ONLY)
+		dev->can.ctrlmode_supported |= CAN_CTRLMODE_LISTENONLY;
+
+	if (bt_const->feature & GS_CAN_FEATURE_LOOP_BACK)
+		dev->can.ctrlmode_supported |= CAN_CTRLMODE_LOOPBACK;
+
+	if (bt_const->feature & GS_CAN_FEATURE_TRIPLE_SAMPLE)
+		dev->can.ctrlmode_supported |= CAN_CTRLMODE_3_SAMPLES;
+
+	if (bt_const->feature & GS_CAN_FEATURE_ONE_SHOT)
+		dev->can.ctrlmode_supported |= CAN_CTRLMODE_ONE_SHOT;
+
+	kfree(bt_const);
+
+	SET_NETDEV_DEV(netdev, &intf->dev);
+
+	rc = register_candev(dev->netdev);
+	if (rc) {
+		free_candev(dev->netdev);
+		dev_err(&intf->dev, "Couldn't register candev\n");
+		return rc;
+	}
+
+	*out = dev;
+	return 0;
+}
+
+static void gs_destroy_candev(struct gs_can *dev)
+{
+	unregister_candev(dev->netdev);
+	free_candev(dev->netdev);
+	usb_kill_anchored_urbs(&dev->tx_submitted);
+}
+
+static int gs_usb_probe(struct usb_interface *intf,
+	const struct usb_device_id *id)
+{
+	struct gs_usb *dev;
+	int rc = -ENOMEM;
+	unsigned int icount, i;
+	struct gs_host_config *hconf;
+	struct gs_device_config *dconf;
+
+	hconf = kmalloc(sizeof(*hconf), GFP_KERNEL);
+	if (!hconf)
+		return -ENOMEM;
+
+	hconf->byte_order = 0x0000beef;
+
+
+	/* send host config */
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_HOST_FORMAT,
+			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			1,
+			intf->altsetting[0].desc.bInterfaceNumber,
+			hconf,
+			sizeof(*hconf),
+			1000);
+
+	kfree(hconf);
+
+	if (rc < 0) {
+		dev_err(&intf->dev, "Couldn't send data format: %d\n",
+			rc);
+		return rc;
+	}
+
+
+	dconf = kmalloc(sizeof(*dconf), GFP_KERNEL);
+	if (!dconf)
+		return -ENOMEM;
+
+	/* read device config */
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_DEVICE_CONFIG,
+			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			1,
+			intf->altsetting[0].desc.bInterfaceNumber,
+			dconf,
+			sizeof(*dconf),
+			1000);
+	if (rc < 0) {
+		dev_err(&intf->dev, "Couldn't recieve device config: %d\n",
+			rc);
+
+		kfree(dconf);
+
+		return rc;
+	}
+
+	icount = dconf->icount+1;
+
+	kfree(dconf);
+
+	dev_info(&intf->dev, "Configuring for %d interfaces\n", icount);
+
+	if (icount > MAX_INTF) {
+		dev_err(&intf->dev,
+			"Driver cannot handle more that %d Can interfaces\n",
+			MAX_INTF);
+		return -EINVAL;
+	}
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	init_usb_anchor(&dev->rx_submitted);
+
+	atomic_set(&dev->active_channels, 0);
+
+	usb_set_intfdata(intf, dev);
+
+	for (i = 0; i < icount; i++) {
+		rc = gs_make_candev(&dev->canch[i], i, intf);
+		if (rc) {
+			/* on failure destroy previously created candevs */
+			icount = i;
+			for (i = 0; i < icount; i++) {
+				gs_destroy_candev(dev->canch[i]);
+				dev->canch[icount] = NULL;
+			}
+			return rc;
+		}
+		dev->canch[i]->parent = dev;
+	}
+
+	dev_info(&intf->dev, "Probe\n");
+	return 0;
+}
+
+static void gs_usb_disconnect(struct usb_interface *intf)
+{
+	unsigned i;
+	struct gs_usb *dev = usb_get_intfdata(intf);
+	usb_set_intfdata(intf, NULL);
+
+	if (!dev) {
+		dev_err(&intf->dev, "Disconnect (nodata)\n");
+		return;
+	}
+
+	for (i = 0; i < MAX_INTF; i++) {
+		struct gs_can *can = dev->canch[i];
+
+		if (!can)
+			continue;
+
+		gs_destroy_candev(can);
+	}
+
+	usb_kill_anchored_urbs(&dev->rx_submitted);
+}
+
+MODULE_DEVICE_TABLE(usb, gs_usb_table);
+
+static struct usb_device_id gs_usb_table[] = {
+	{USB_DEVICE(USB_GSUSB_1_VENDOR_ID, USB_GSUSB_1_PRODUCT_ID)},
+	{} /* Terminating entry */
+};
+
+static struct usb_driver gs_usb_driver = {
+	.name       = "gs_usb",
+	.probe      = gs_usb_probe,
+	.disconnect = gs_usb_disconnect,
+	.id_table   = gs_usb_table
+};
+
+static int __init gs_usb_init(void)
+{
+	return usb_register(&gs_usb_driver);
+}
+
+static void __exit gs_usb_exit(void)
+{
+	usb_deregister(&gs_usb_driver);
+}
+
+module_init(gs_usb_init);
+module_exit(gs_usb_exit);
+
+MODULE_AUTHOR("Maximilian Schneider <mws@schneidersoft.net>");
+MODULE_DESCRIPTION(
+"Socket CAN device driver for Geschwister Schneider Technologie-, "
+"Entwicklungs- und Vertriebs UG. USB2.0 to CAN interfaces.");
+MODULE_LICENSE("GPL v2");
+
-- 
1.7.10.4

Re: GS_USB

[Wolfgang Grandegger]

On 11/03/2013 06:12 PM, Max S. wrote:
> Any progress on reviewing the GS_USB driver code?
> 
> I have added asynchronous state update. Here is the latest patch.

Great, actually I was waiting for support of the asynchronous state
changes... Will have a closer look later this week.

Wolfgang,

Re: GS_USB

[Wolfgang Grandegger]

Hi Max,

On 11/03/2013 06:12 PM, Max S. wrote:
> Any progress on reviewing the GS_USB driver code?
> 
> I have added asynchronous state update. Here is the latest patch.
> 
> 
>>From 346f223bb3a8f4435f93cdfbc5e06db2cbf7179d Mon Sep 17 00:00:00 2001
> From: Maximilian Schneider <max@schneidersoft.net>
> Date: Sun, 3 Nov 2013 16:57:06 +0000
> Subject: [PATCH] Added support for the GS_USB CAN devices.

Please add some more lines here about the driver. Also, the patch below
is line wrapped. Make sure that your mail client does not mangle white
space.

> Signed-off-by: Maximilian Schneider <max@schneidersoft.net>
> ---
>  drivers/net/can/usb/Kconfig  |    8 +
>  drivers/net/can/usb/Makefile |    1 +
>  drivers/net/can/usb/gs_usb.c | 1037
> ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 1046 insertions(+)
>  create mode 100644 drivers/net/can/usb/gs_usb.c
> 
> diff --git a/drivers/net/can/usb/Kconfig b/drivers/net/can/usb/Kconfig
> index fc96a3d..f5e3e8c 100644
> --- a/drivers/net/can/usb/Kconfig
> +++ b/drivers/net/can/usb/Kconfig
> @@ -54,4 +54,12 @@ config CAN_8DEV_USB
>  	  This driver supports the USB2CAN interface
>  	  from 8 devices (http://www.8devices.com).
>  
> +config CAN_GS_USB
> +	tristate "Geschwister Schneider UG interfaces"
> +	---help---
> +	  This driver supports the Geschwister Schneider USB/CAN devices.
> +	  If unsure choose N,
> +	  choose Y for built in support,
> +	  M to compile as module (module will be named: gs_usb).
> +
>  endmenu
> diff --git a/drivers/net/can/usb/Makefile b/drivers/net/can/usb/Makefile
> index becef46..c21a521 100644
> --- a/drivers/net/can/usb/Makefile
> +++ b/drivers/net/can/usb/Makefile
> @@ -7,5 +7,6 @@ obj-$(CONFIG_CAN_ESD_USB2) += esd_usb2.o
>  obj-$(CONFIG_CAN_KVASER_USB) += kvaser_usb.o
>  obj-$(CONFIG_CAN_PEAK_USB) += peak_usb/
>  obj-$(CONFIG_CAN_8DEV_USB) += usb_8dev.o
> +obj-$(CONFIG_CAN_GS_USB) += gs_usb.o
>  
>  ccflags-$(CONFIG_CAN_DEBUG_DEVICES) := -DDEBUG
> diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
> new file mode 100644
> index 0000000..4aa28c0
> --- /dev/null
> +++ b/drivers/net/can/usb/gs_usb.c
> @@ -0,0 +1,1037 @@
> +/* CAN driver for Geschwister Schneider USB/CAN devices.
> + *
> + * Copyright (C) 2013 Geschwister Schneider Technologie-,
> + * Entwicklungs- und Vertriebs UG (Haftungsbeschränkt).
> + *
> + * Many thanks to all socketcan devs!
> + *
> + * This program is free software; you can redistribute it and/or modify
> it
> + * under the terms of the GNU General Public License as published
> + * by the Free Software Foundation; version 2 of the License.
> + *
> + * This program is distributed in the hope that it will be useful, but
> + * WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * General Public License for more details.
> + */
> +
> +#include <linux/init.h>
> +#include <linux/signal.h>
> +#include <linux/module.h>
> +#include <linux/netdevice.h>
> +#include <linux/usb.h>
> +
> +#include <linux/can.h>
> +#include <linux/can/dev.h>
> +#include <linux/can/error.h>
> +
> +/* Device specific constants */
> +#define USB_GSUSB_1_VENDOR_ID      0x1d50
> +#define USB_GSUSB_1_PRODUCT_ID     0x606f
> +
> +#define GSUSB_ENDPOINT_IN          1
> +#define GSUSB_ENDPOINT_OUT         2
> +
> +/* Device specific constants */
> +enum gs_usb_breq {
> +	GS_USB_BREQ_HOST_FORMAT = 0,
> +	GS_USB_BREQ_BITTIMING,
> +	GS_USB_BREQ_MODE,
> +	GS_USB_BREQ_BERR,
> +	GS_USB_BREQ_BT_CONST,
> +	GS_USB_BREQ_DEVICE_CONFIG
> +};
> +
> +enum gs_can_mode {
> +	GS_CAN_MODE_RESET = 0,
> +	GS_CAN_MODE_START
> +};
> +
> +enum gs_can_state {
> +	GS_CAN_STATE_ERROR_ACTIVE = 0,
> +	GS_CAN_STATE_ERROR_WARNING,
> +	GS_CAN_STATE_ERROR_PASSIVE,
> +	GS_CAN_STATE_BUS_OFF,
> +	GS_CAN_STATE_STOPPED,
> +	GS_CAN_STATE_SLEEPING
> +};
> +
> +/* data types passed between host and device */
> +struct __packed gs_host_config {
> +	u32 byte_order;
> +};

It's more common to add __packed after the closing bracket "}".

> +
> +struct __packed gs_device_config {
> +	u8 reserved1;
> +	u8 reserved2;
> +	u8 reserved3;
> +	u8 icount;
> +	u32 sw_version;
> +	u32 hw_version;
> +};
> +
> +#define GS_CAN_MODE_NORMAL               0
> +#define GS_CAN_MODE_LISTEN_ONLY          (1<<0)
> +#define GS_CAN_MODE_LOOP_BACK            (1<<1)
> +#define GS_CAN_MODE_TRIPLE_SAMPLE        (1<<2)
> +#define GS_CAN_MODE_ONE_SHOT             (1<<3)
> +
> +struct __packed gs_device_mode {
> +	u32 mode;
> +	u32 flags;
> +};
> +
> +struct __packed gs_device_state {
> +	u32 state;
> +	u32 rxerr;
> +	u32 txerr;
> +};
> +
> +struct __packed gs_device_bittiming {
> +	u32 prop_seg;
> +	u32 phase_seg1;
> +	u32 phase_seg2;
> +	u32 sjw;
> +	u32 brp;
> +};
> +
> +#define GS_CAN_FEATURE_LISTEN_ONLY      (1<<0)
> +#define GS_CAN_FEATURE_LOOP_BACK        (1<<1)
> +#define GS_CAN_FEATURE_TRIPLE_SAMPLE    (1<<2)
> +#define GS_CAN_FEATURE_ONE_SHOT         (1<<3)
> +
> +struct __packed gs_device_bt_const {
> +	u32 feature;
> +	u32 fclk_can;
> +	u32 tseg1_min;
> +	u32 tseg1_max;
> +	u32 tseg2_min;
> +	u32 tseg2_max;
> +	u32 sjw_max;
> +	u32 brp_min;
> +	u32 brp_max;
> +	u32 brp_inc;
> +};
> +
> +#define GS_CAN_FLAG_OVERFLOW 1
> +
> +struct __packed gs_host_frame {
> +	u32 echo_id;
> +	u32 can_id;
> +
> +	u8 can_dlc;
> +	u8 channel;
> +	u8 flags;
> +	u8 reserved;
> +
> +	u8 data[8];
> +};
> +
> +/* Special address description flags for the CAN_ID */
> +#define GS_EFF_FLAG 0x80000000U /* EFF/SFF is set in the MSB */
> +#define GS_RTR_FLAG 0x40000000U /* remote transmission request */
> +#define GS_ERR_FLAG 0x20000000U /* error frame */
> +
> +/* Valid bits in CAN ID for frame formats */
> +#define GS_SFF_MASK 0x000007FFU /* standard frame format (SFF) */
> +#define GS_EFF_MASK 0x1FFFFFFFU /* extended frame format (EFF) */
> +#define GS_ERR_MASK 0x1FFFFFFFU /* omit EFF, RTR, ERR flags */

You redefine the CAN flags and mask here but in many places you
silentely assume that they are identical, e.g. via:

   cf->can_id = hf->can_id;

Not sure how to handle this transprently. I think these defines will
never change. Either use the CAN flags and mask directly (like you
already do for the error frames) or properly remap/copy all flags and
values. Other opinions?

> +/* Only send a max of MAX_TX_URBS frames per channel to the device at a
> time. */
> +#define MAX_TX_URBS 10
> +/* Only launch a max of MAX_RX_URBS usb requests at a time. */
> +#define MAX_RX_URBS 30
> +/* Maximum number of interfaces the driver supports per device.
> + * Current hardware only supports 2 interfaces. The future may vary.
> + */
> +#define MAX_INTF 2

Please use a prefix here as well.

> +
> +struct gs_tx_context {
> +	struct gs_can *dev;
> +	unsigned int echo_id;
> +};
> +
> +struct gs_can {
> +	struct can_priv can; /* must be the first member */
> +
> +	struct gs_usb *parent;
> +
> +	struct net_device *netdev;
> +	struct usb_device *udev;
> +	struct usb_interface *iface;
> +
> +	struct can_bittiming_const bt_const;
> +	unsigned int channel;	/* channel number */
> +
> +	/* This lock prevents a race condition
> +	 * between xmit and recieve.
> +	 */

Does fit on one line?

> +	spinlock_t tx_ctx_lock;
> +	struct gs_tx_context tx_context[MAX_TX_URBS];
> +
> +	struct usb_anchor tx_submitted;
> +	atomic_t active_tx_urbs;
> +};
> +
> +/* usb interface struct */
> +struct gs_usb {
> +	struct gs_can *canch[MAX_INTF];
> +
> +	struct usb_anchor rx_submitted;
> +
> +	atomic_t active_channels;
> +};

Looks better without empty lines.

> +
> +/* 'allocate' a tx context.
> + * returns a valid tx context or NULL if there is no space.
> + */
> +static struct gs_tx_context *gs_alloc_tx_context(struct gs_can *dev)
> +{
> +	int i = 0;
> +

Remove empty line please.

> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&dev->tx_ctx_lock, flags);
> +
> +	for (; i < MAX_TX_URBS; i++) {
> +		if (dev->tx_context[i].echo_id == MAX_TX_URBS) {
> +			dev->tx_context[i].echo_id = i;
> +			spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
> +			return &dev->tx_context[i];
> +		}
> +	}
> +
> +	spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
> +	return NULL;
> +}
> +
> +/* releases a tx context
> + */
> +static void gs_free_tx_context(struct gs_tx_context *txc)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&txc->dev->tx_ctx_lock, flags);
> +	txc->echo_id = MAX_TX_URBS;
> +	spin_unlock_irqrestore(&txc->dev->tx_ctx_lock, flags);

Such assignments re done with one instruction. No need to make it event
more atomic.

> +}
> +
> +/* Get a tx context by id.
> + */
> +static struct gs_tx_context *gs_get_tx_context(
> +	struct gs_can *dev,
> +	unsigned int id)

Please use a common style, also for the continuation lines.

> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&dev->tx_ctx_lock, flags);
> +	if (id < MAX_TX_URBS) {
> +		if (dev->tx_context[id].echo_id == id) {
> +			spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
> +			return &dev->tx_context[id];
> +		}
> +	}
> +	spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
> +	return NULL;
> +}
> +
> +/* Get a tx contexts id.
> + */
> +static unsigned int gs_tx_context_id(struct gs_tx_context *txc)
> +{
> +	unsigned int id;
> +

Remove empty line please.

> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&txc->dev->tx_ctx_lock, flags);
> +	id = txc->echo_id;
> +	spin_unlock_irqrestore(&txc->dev->tx_ctx_lock, flags);
> +	return id;

See my comments above.

> +}
> +
> +static int gs_cmd_reset(struct gs_usb *gsusb, struct gs_can *gsdev)
> +{
> +	struct gs_device_mode *dm;
> +	struct usb_interface *intf = gsdev->iface;
> +	int rc;
> +
> +	dm = kzalloc(sizeof(*dm), GFP_KERNEL);
> +	if (!dm)
> +		return -ENOMEM;
> +
> +	dm->mode = GS_CAN_MODE_RESET;
> +
> +	rc = usb_control_msg(interface_to_usbdev(intf),
> +			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
> +			GS_USB_BREQ_MODE,
> +			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			gsdev->channel,
> +			0,
> +			dm,
> +			sizeof(*dm),
> +			1000);
> +
> +	return rc;
> +}
> +
> +static void gs_update_state(struct gs_can *dev, struct can_frame *cf)
> +{
> +	if (cf->can_id & CAN_ERR_BUSOFF) {
> +		dev->can.state = CAN_STATE_BUS_OFF;

In case of bus-off. What does the hardware do? How does it recover? Is
recovery triggered by software possible? Is it possible to support
manual recovery?

> +	} else if (cf->can_id & CAN_ERR_CRTL) {
> +		dev->can.state = CAN_STATE_ERROR_ACTIVE;


This means back to error active, right?

> +		if ((cf->data[1] & CAN_ERR_CRTL_TX_WARNING) ||
> +			(cf->data[1] & CAN_ERR_CRTL_RX_WARNING))

Here you assume that the mask and flags do match the CAN_* definitions.
See my comment above.

> +			dev->can.state = CAN_STATE_ERROR_WARNING;
> +
> +		if ((cf->data[1] & CAN_ERR_CRTL_TX_PASSIVE) ||
> +			(cf->data[1]&CAN_ERR_CRTL_RX_PASSIVE))

s/&/ & /

> +			dev->can.state = CAN_STATE_ERROR_PASSIVE;
> +	}

Also please update the stats accordingly:

	can_stats.bus_off++;
	can_stats.error_warning++
	can_stats.error_passive++

Apart from that, the state handling is rather basic but totaly
sufficient. Would be nice if you could show the state handling
and bus-off recovery by reporting the output of "$ candump -td -e
any,0:0,#FFFFFFFF" while sending messages to the device ...

1. without cable connected (entering error passive)
2. with short-circuited CAN high and low (entering bus-off)

> +}
> +
> +/**************************** USB CALLBACKS **************************/

Please respect the linux coding style, also for comments.

> +static void gs_usb_recieve_bulk_callback(struct urb *urb)
> +{
> +	struct gs_usb *usbcan = urb->context;
> +	struct gs_can *dev;
> +	struct net_device *netdev;
> +	int rc;
> +	struct net_device_stats *stats;
> +	struct gs_host_frame *hf = urb->transfer_buffer;
> +	struct gs_tx_context *txc;
> +

Remove empty line please.

	struct can_frame *cf;
> +	struct sk_buff *skb;
> +
> +	BUG_ON(!usbcan);
> +
> +	switch (urb->status) {
> +	case 0: /* success */
> +		break;
> +	case -ENOENT:
> +	case -ESHUTDOWN:
> +		return;
> +	default:
> +		/* do not resubmit aborted urbs. eg: when device goes down */
> +		return;
> +	}
> +
> +	/* device reports out of range channel id */
> +	if (hf->channel >= MAX_INTF)
> +		goto resubmit_urb;
> +
> +	/* device reports bad channel id */
> +	dev = usbcan->canch[hf->channel];
> +
> +	netdev = dev->netdev;
> +
> +	if (!netif_device_present(netdev))
> +		return;
> +
> +	stats = &dev->netdev->stats;
> +
> +	if (hf->echo_id == -1) { /* normal rx */
> +		skb = alloc_can_skb(dev->netdev, &cf);
> +		if (skb == NULL)
> +			return;
> +
> +		cf->can_id = hf->can_id;

What about endianess? I think the driver should care.

> +		/* is it necessary to use get_can_dlc? */
> +		cf->can_dlc = get_can_dlc(hf->can_dlc);
> +		memcpy(cf->data, hf->data, 8);
> +
> +		/* ERROR frames tell us information about the controler */

s/controler/controller/

> +		if (hf->can_id & GS_ERR_FLAG)
> +			gs_update_state(dev, cf);
> +
> +		netif_rx(skb);
> +
> +		netdev->stats.rx_packets++;
> +		netdev->stats.rx_bytes += hf->can_dlc;
> +	} else { /* echo_id == hf->echo_id */
> +		if (hf->echo_id >= MAX_TX_URBS) {
> +			netdev_err(netdev,
> +				"Device sent an out of range echo id:%d\n",

s/:/ /

> +				hf->echo_id);
> +			goto resubmit_urb;
> +		}
> +
> +		netdev->stats.tx_packets++;
> +		netdev->stats.tx_bytes += hf->can_dlc;
> +
> +		txc = gs_get_tx_context(dev, hf->echo_id);
> +
> +		/* bad devices send bad echo_ids. */
> +		if (!txc) {
> +			netdev_err(netdev,
> +				"Device sent a bad echo id:%d\n",
> +				hf->echo_id);

Ditto

> +			goto resubmit_urb;
> +		}
> +
> +		can_get_echo_skb(netdev, gs_tx_context_id(txc));
> +
> +		gs_free_tx_context(txc);
> +
> +		netif_wake_queue(netdev);
> +	}
> +
> +	if (hf->flags & GS_CAN_FLAG_OVERFLOW) {
> +		skb = alloc_can_err_skb(netdev, &cf);
> +		if (skb == NULL)
> +			goto resubmit_urb;
> +
> +		cf->can_id |= CAN_ERR_CRTL;
> +		cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
> +		stats->rx_over_errors++;
> +		stats->rx_errors++;
> +		netif_rx(skb);
> +	}
> +

Only one empty line.

> +
> +resubmit_urb:
> +	/* note: no urb refill... works for me */
> +
> +	rc = usb_submit_urb(urb, GFP_ATOMIC);
> +
> +	/* USB failure take down all interfaces */
> +	if (rc == -ENODEV) {
> +		for (rc = 0; rc < MAX_INTF; rc++) {
> +			if (usbcan->canch[rc])
> +				netif_device_detach(usbcan->canch[rc]->netdev);
> +		}
> +	}
> +}
> +
> +static int gs_usb_set_bittiming(struct net_device *netdev)
> +{
> +	struct gs_can *dev = netdev_priv(netdev);
> +	struct can_bittiming *bt = &dev->can.bittiming;
> +	struct usb_interface *intf = dev->iface;
> +	int rc;
> +	struct gs_device_bittiming *dbt;
> +
> +	dbt = kmalloc(sizeof(*dbt), GFP_KERNEL);
> +	if (!dbt)
> +		return -ENOMEM;
> +
> +	dbt->prop_seg = bt->prop_seg;
> +	dbt->phase_seg1 = bt->phase_seg1;
> +	dbt->phase_seg2 = bt->phase_seg2;
> +	dbt->sjw = bt->sjw;
> +	dbt->brp = bt->brp;
> +
> +	rc = usb_control_msg(interface_to_usbdev(intf),
> +			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
> +			GS_USB_BREQ_BITTIMING,
> +			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			dev->channel,
> +			0,
> +			dbt,
> +			sizeof(*dbt),
> +			1000);
> +	if (rc < 0)
> +		dev_err(netdev->dev.parent, "Couldn't set bittimings %d", rc);
> +
> +	kfree(dbt);
> +
> +	return rc;
> +}
> +
> +static int gs_usb_set_mode(struct net_device *netdev, enum can_mode
> mode)
> +{
> +	if (mode == CAN_MODE_START) {
> +		netif_wake_queue(netdev);
> +		return 0;
> +	}

This is usually used for bus off recovery by the software. If it's not
possible, you should drop this callback.

> +
> +	return -EOPNOTSUPP;
> +}
> +
> +static void gs_usb_xmit_callback(struct urb *urb)
> +{
> +	struct gs_tx_context *txc = urb->context;
> +	struct gs_can *dev;
> +	struct net_device *netdev;
> +
> +	dev = txc->dev;
> +
> +	netdev = dev->netdev;

You can do the assignment directly in the function header, like for
gs_tx_context.

> +
> +	if (urb->status) {
> +		netdev_info(netdev, "%d] xmit err %d\n",
> +			dev->channel, txc->echo_id);
> +	}
> +
> +	usb_free_coherent(urb->dev,
> +		urb->transfer_buffer_length,
> +		urb->transfer_buffer,
> +		urb->transfer_dma);
> +
> +	atomic_dec(&dev->active_tx_urbs);
> +
> +	if (!netif_device_present(netdev))
> +		return;
> +
> +	if (netif_queue_stopped(netdev))
> +		netif_wake_queue(netdev);
> +}
> +
> +static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
> +	struct net_device *netdev)
> +{
> +	struct gs_can *dev = netdev_priv(netdev);
> +	struct net_device_stats *stats = &dev->netdev->stats;
> +	struct urb *urb;
> +	struct gs_host_frame *hf;
> +	struct can_frame *cf;
> +	int rc;
> +	unsigned int idx;
> +	struct gs_tx_context *txc;
> +
> +	if (dev->can.ctrlmode&CAN_CTRLMODE_LISTENONLY)

s/&/ & /

> +		return NETDEV_TX_BUSY;
> +
> +	if (can_dropped_invalid_skb(netdev, skb))
> +		return NETDEV_TX_OK;
> +
> +	/* find an empty context to keep track of transmission */
> +	txc = gs_alloc_tx_context(dev);
> +	if (!txc)
> +		return NETDEV_TX_BUSY;
> +
> +	/* create a URB, and a buffer for it */
> +	urb = usb_alloc_urb(0, GFP_ATOMIC);
> +	if (!urb) {
> +		netdev_err(netdev, "No memory left for URBs\n");
> +		goto nomem_urb;
> +	}
> +
> +	hf = usb_alloc_coherent(dev->udev, sizeof(*hf), GFP_ATOMIC,
> +		&urb->transfer_dma);
> +	if (!hf) {
> +		netdev_err(netdev, "No memory left for USB buffer\n");
> +		goto nomem_hf;
> +	}
> +
> +	cf = (struct can_frame *)skb->data;

Could be moved down ...

> +
> +	idx = gs_tx_context_id(txc);
> +
> +	if (idx >= MAX_TX_URBS) {
> +		netdev_err(netdev, "Invalid tx context %d\n", idx);
> +		goto badidx;
> +	}
> +
> +	hf->echo_id = idx;
> +	hf->channel = dev->channel;

... here.

> +	hf->can_id = cf->can_id;

Endianess?

> +	hf->can_dlc = cf->can_dlc;
> +	memcpy(hf->data, cf->data, 8);
> +
> +	usb_fill_bulk_urb(urb, dev->udev,
> +			usb_sndbulkpipe(dev->udev, GSUSB_ENDPOINT_OUT),
> +			hf,
> +			sizeof(*hf),
> +			gs_usb_xmit_callback,
> +			txc);
> +
> +	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
> +	usb_anchor_urb(urb, &dev->tx_submitted);
> +
> +	can_put_echo_skb(skb, netdev, idx);
> +
> +	atomic_inc(&dev->active_tx_urbs);
> +
> +	rc = usb_submit_urb(urb, GFP_ATOMIC);
> +	if (unlikely(rc)) {			/* usb send failed */
> +		atomic_dec(&dev->active_tx_urbs);
> +
> +		netdev_err(netdev, "usb_submit failed %d\n", rc);
> +
> +		can_free_echo_skb(netdev, gs_tx_context_id(txc));
> +		gs_free_tx_context(txc);
> +
> +		usb_unanchor_urb(urb);
> +		usb_free_coherent(dev->udev,
> +			sizeof(*hf),
> +			hf,
> +			urb->transfer_dma);
> +
> +

Only one empty line please.

> +		if (rc == -ENODEV) {
> +			netif_device_detach(netdev);
> +		} else {
> +			netdev_err(netdev, "Failed tx_urb %d\n", rc);
> +

Looks better without empty line.

> +			stats->tx_dropped++;
> +		}
> +	} else {
> +		netdev->trans_start = jiffies;
> +
> +		/* Slow down tx path */
> +		if (atomic_read(&dev->active_tx_urbs) >= MAX_TX_URBS)
> +			netif_stop_queue(netdev);
> +	}
> +
> +	/* let usb core take care of this urb */
> +	usb_free_urb(urb);
> +
> +	return NETDEV_TX_OK;
> +
> +badidx:
> +	usb_free_coherent(dev->udev,
> +				sizeof(*hf),
> +				hf,
> +				urb->transfer_dma);
> +nomem_hf:
> +	usb_free_urb(urb);
> +
> +nomem_urb:
> +	gs_free_tx_context(txc);
> +	dev_kfree_skb(skb);
> +	stats->tx_dropped++;
> +	return NETDEV_TX_OK;
> +}
> +
> +static int gs_can_open(struct net_device *netdev)
> +{
> +	struct gs_can *dev = netdev_priv(netdev);
> +	struct gs_usb *parent = dev->parent;
> +	int rc, i;
> +	struct gs_device_mode *dm;
> +	u32 ctrlmode;
> +
> +	/* common open */
> +	rc = open_candev(netdev);
> +	if (rc)
> +		return rc;
> +
> +	if (atomic_add_return(1, &parent->active_channels) == 1) {
> +		for (i = 0; i < MAX_RX_URBS; i++) {
> +			struct urb *urb = NULL;
> +			u8 *buf = NULL;
> +
> +			/* alloc rx urb */
> +			urb = usb_alloc_urb(0, GFP_KERNEL);
> +			if (!urb) {
> +				netdev_err(netdev,
> +					"No memory left for URBs\n");
> +				return -ENOMEM;
> +			}
> +
> +			/* alloc rx buffer */
> +			buf = usb_alloc_coherent(dev->udev,
> +				sizeof(struct gs_host_frame),
> +				GFP_KERNEL,
> +				&urb->transfer_dma);
> +			if (!buf) {
> +				netdev_err(netdev,
> +					"No memory left for USB buffer\n");
> +				usb_free_urb(urb);
> +				return -ENOMEM;
> +			}
> +

Only one empty line.

> +
> +			/* fill, anchor, and submit rx urb */
> +			usb_fill_bulk_urb(urb,
> +					dev->udev,
> +					usb_rcvbulkpipe(dev->udev,
> +						GSUSB_ENDPOINT_IN),
> +					buf,
> +					sizeof(struct gs_host_frame),
> +					gs_usb_recieve_bulk_callback,
> +					parent
> +					);
> +			urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
> +
> +			usb_anchor_urb(urb, &parent->rx_submitted);
> +
> +			rc = usb_submit_urb(urb, GFP_KERNEL);
> +			if (rc) {
> +				if (rc == -ENODEV)
> +					netif_device_detach(dev->netdev);
> +
> +				usb_unanchor_urb(urb);
> +				break;
> +			}
> +
> +			/* Drop reference,
> +			 * USB core will take care of freeing it
> +			 */
> +			usb_free_urb(urb);
> +		}
> +	}
> +
> +	dm = kmalloc(sizeof(*dm), GFP_KERNEL);
> +	if (!dm)
> +		return -ENOMEM;
> +
> +	/* flags */
> +	ctrlmode = dev->can.ctrlmode;
> +	dm->flags = 0;
> +
> +	if (ctrlmode & CAN_CTRLMODE_LOOPBACK)
> +		dm->flags |= GS_CAN_MODE_LOOP_BACK;
> +
> +	else if (ctrlmode & CAN_CTRLMODE_LISTENONLY)
> +		dm->flags |= GS_CAN_MODE_LISTEN_ONLY;
> +
> +

Ditto

> +	/* Controller is not allowed to retry TX
> +	 * this mode is unavailable on atmels uc3c hardware
> +	 */
> +	if (ctrlmode & CAN_CTRLMODE_ONE_SHOT)
> +		dm->flags |= GS_CAN_MODE_ONE_SHOT;

Have you tested oneshot mode.

> +	if (ctrlmode & CAN_CTRLMODE_3_SAMPLES)
> +		dm->flags |= GS_CAN_MODE_TRIPLE_SAMPLE;
> +
> +	/* finally start device */
> +	dm->mode = GS_CAN_MODE_START;
> +	rc = usb_control_msg(interface_to_usbdev(dev->iface),
> +			usb_sndctrlpipe(interface_to_usbdev(dev->iface), 0),
> +			GS_USB_BREQ_MODE,
> +			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			dev->channel,
> +			0,
> +			dm,
> +			sizeof(*dm),
> +			1000);
> +
> +	if (rc < 0) {
> +		netdev_err(netdev, "Couldn't start device %d\n", rc);

s/%d/ (err=%d)/ ?

> +		kfree(dm);
> +		return rc;
> +	}
> +
> +	/* check mode... */
> +	if (!dm)
> +		return -ENOMEM;
> +
> +	rc = usb_control_msg(interface_to_usbdev(dev->iface),
> +			usb_rcvctrlpipe(interface_to_usbdev(dev->iface), 0),
> +			GS_USB_BREQ_MODE,
> +			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			dev->channel,
> +			0,
> +			dm,
> +			sizeof(*dm),
> +			1000);
> +
> +	if (rc < 0) {
> +		netdev_err(netdev, "Couldn't get device mode %d\n",
> +			rc);

Ditto.

> +		kfree(dm);
> +		return rc;
> +	}
> +
> +	kfree(dm);
> +
> +	dev->can.state = CAN_STATE_ERROR_ACTIVE;
> +
> +	netif_start_queue(netdev);
> +
> +	netdev_info(netdev, "CAN open\n");

Please remove.

> +	return 0;
> +}
> +
> +static int gs_can_close(struct net_device *netdev)
> +{
> +	int rc;
> +	struct gs_can *dev = netdev_priv(netdev);
> +	struct gs_usb *parent = dev->parent;
> +
> +	netif_stop_queue(netdev);
> +
> +	/* Stop polling */
> +	if (atomic_dec_and_test(&parent->active_channels))
> +		usb_kill_anchored_urbs(&parent->rx_submitted);
> +
> +	rc = gs_cmd_reset(parent, dev);
> +
> +	if (rc < 0)
> +		netdev_warn(netdev, "Couldn't shutdown device %d", rc);

device %d is confusing. See above.

> +
> +	close_candev(netdev);
> +
> +	return 0;
> +}
> +
> +/******************************** USB ********************************/
> +
> +static const struct net_device_ops gs_usb_netdev_ops = {
> +	.ndo_open = gs_can_open,
> +	.ndo_stop = gs_can_close,
> +	.ndo_start_xmit = gs_can_start_xmit,
> +};
> +
> +static int gs_make_candev(struct gs_can **out, unsigned int channel,
> +	struct usb_interface *intf)
> +{
> +	struct gs_can *dev;
> +	struct net_device *netdev;
> +	int rc;
> +	struct gs_device_bt_const *bt_const;
> +
> +	bt_const = kmalloc(sizeof(*bt_const), GFP_KERNEL);
> +	if (!bt_const)
> +		return -ENOMEM;
> +
> +	/* fetch bit timing constants */
> +	rc = usb_control_msg(interface_to_usbdev(intf),
> +			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
> +			GS_USB_BREQ_BT_CONST,
> +			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			channel,
> +			0,
> +			bt_const,
> +			sizeof(*bt_const),
> +			1000);
> +
> +	if (rc < 0) {
> +		dev_err(&intf->dev,
> +			"Couldn't get bit timing const for channel %d\n",

Ditto

> +			rc);
> +		kfree(bt_const);
> +		return rc;
> +	}
> +
> +	/* create netdev */
> +	netdev = alloc_candev(sizeof(struct gs_can), MAX_TX_URBS);
> +	if (!netdev) {
> +		dev_err(&intf->dev, "Couldn't alloc candev\n");
> +		kfree(bt_const);
> +		return -ENOMEM;
> +	}
> +
> +	dev = netdev_priv(netdev);
> +
> +	netdev->netdev_ops = &gs_usb_netdev_ops;
> +
> +	netdev->flags |= IFF_ECHO; /* we support full roundtrip echo */
> +
> +	/* dev settup */
> +	strcpy(dev->bt_const.name, "gs_usb");
> +	dev->bt_const.tseg1_min = bt_const->tseg1_min;
> +	dev->bt_const.tseg1_max = bt_const->tseg1_max;
> +	dev->bt_const.tseg2_min = bt_const->tseg2_min;
> +	dev->bt_const.tseg2_max = bt_const->tseg2_max;
> +	dev->bt_const.sjw_max = bt_const->sjw_max;
> +	dev->bt_const.brp_min = bt_const->brp_min;
> +	dev->bt_const.brp_max = bt_const->brp_max;
> +	dev->bt_const.brp_inc = bt_const->brp_inc;
> +
> +	dev->udev = interface_to_usbdev(intf);
> +	dev->iface = intf;
> +	dev->netdev = netdev;
> +	dev->channel = channel;
> +
> +	init_usb_anchor(&dev->tx_submitted);
> +	atomic_set(&dev->active_tx_urbs, 0);
> +	spin_lock_init(&dev->tx_ctx_lock);
> +	for (rc = 0; rc < MAX_TX_URBS; rc++) {
> +		dev->tx_context[rc].dev = dev;
> +		dev->tx_context[rc].echo_id = MAX_TX_URBS;
> +	}
> +
> +	/* can settup */
> +	dev->can.state = CAN_STATE_STOPPED;
> +	dev->can.clock.freq = bt_const->fclk_can;
> +	dev->can.bittiming_const = &dev->bt_const;
> +	dev->can.do_set_bittiming = gs_usb_set_bittiming;
> +	dev->can.do_set_mode = gs_usb_set_mode;
> +
> +	dev->can.ctrlmode_supported = 0;
> +
> +	if (bt_const->feature & GS_CAN_FEATURE_LISTEN_ONLY)
> +		dev->can.ctrlmode_supported |= CAN_CTRLMODE_LISTENONLY;
> +
> +	if (bt_const->feature & GS_CAN_FEATURE_LOOP_BACK)
> +		dev->can.ctrlmode_supported |= CAN_CTRLMODE_LOOPBACK;
> +
> +	if (bt_const->feature & GS_CAN_FEATURE_TRIPLE_SAMPLE)
> +		dev->can.ctrlmode_supported |= CAN_CTRLMODE_3_SAMPLES;
> +
> +	if (bt_const->feature & GS_CAN_FEATURE_ONE_SHOT)
> +		dev->can.ctrlmode_supported |= CAN_CTRLMODE_ONE_SHOT;
> +
> +	kfree(bt_const);
> +
> +	SET_NETDEV_DEV(netdev, &intf->dev);
> +
> +	rc = register_candev(dev->netdev);
> +	if (rc) {
> +		free_candev(dev->netdev);
> +		dev_err(&intf->dev, "Couldn't register candev\n");
> +		return rc;
> +	}
> +
> +	*out = dev;

Why not returning "dev" directly. You can pack errors into the pointer
with ERR_PTR(rc).

> +	return 0;
> +}
> +
> +static void gs_destroy_candev(struct gs_can *dev)
> +{
> +	unregister_candev(dev->netdev);
> +	free_candev(dev->netdev);
> +	usb_kill_anchored_urbs(&dev->tx_submitted);
> +}
> +
> +static int gs_usb_probe(struct usb_interface *intf,
> +	const struct usb_device_id *id)
> +{
> +	struct gs_usb *dev;
> +	int rc = -ENOMEM;
> +	unsigned int icount, i;
> +	struct gs_host_config *hconf;
> +	struct gs_device_config *dconf;
> +
> +	hconf = kmalloc(sizeof(*hconf), GFP_KERNEL);
> +	if (!hconf)
> +		return -ENOMEM;
> +
> +	hconf->byte_order = 0x0000beef;
> +

Only one empty line please.

> +
> +	/* send host config */
> +	rc = usb_control_msg(interface_to_usbdev(intf),
> +			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
> +			GS_USB_BREQ_HOST_FORMAT,
> +			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			1,
> +			intf->altsetting[0].desc.bInterfaceNumber,
> +			hconf,
> +			sizeof(*hconf),
> +			1000);
> +
> +	kfree(hconf);
> +
> +	if (rc < 0) {
> +		dev_err(&intf->dev, "Couldn't send data format: %d\n",
> +			rc);
> +		return rc;
> +	}
> +
> +
> +	dconf = kmalloc(sizeof(*dconf), GFP_KERNEL);
> +	if (!dconf)
> +		return -ENOMEM;
> +
> +	/* read device config */
> +	rc = usb_control_msg(interface_to_usbdev(intf),
> +			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
> +			GS_USB_BREQ_DEVICE_CONFIG,
> +			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			1,
> +			intf->altsetting[0].desc.bInterfaceNumber,
> +			dconf,
> +			sizeof(*dconf),
> +			1000);
> +	if (rc < 0) {
> +		dev_err(&intf->dev, "Couldn't recieve device config: %d\n",
> +			rc);
> +
> +		kfree(dconf);
> +
> +		return rc;
> +	}
> +
> +	icount = dconf->icount+1;
> +
> +	kfree(dconf);
> +
> +	dev_info(&intf->dev, "Configuring for %d interfaces\n", icount);
> +
> +	if (icount > MAX_INTF) {
> +		dev_err(&intf->dev,
> +			"Driver cannot handle more that %d Can interfaces\n",

s/Can/CAN/ ?

> +			MAX_INTF);
> +		return -EINVAL;
> +	}
> +
> +	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
> +	init_usb_anchor(&dev->rx_submitted);
> +
> +	atomic_set(&dev->active_channels, 0);
> +
> +	usb_set_intfdata(intf, dev);
> +
> +	for (i = 0; i < icount; i++) {
> +		rc = gs_make_candev(&dev->canch[i], i, intf);
> +		if (rc) {
> +			/* on failure destroy previously created candevs */
> +			icount = i;
> +			for (i = 0; i < icount; i++) {
> +				gs_destroy_candev(dev->canch[i]);
> +				dev->canch[icount] = NULL;
> +			}
> +			return rc;
> +		}
> +		dev->canch[i]->parent = dev;
> +	}
> +
> +	dev_info(&intf->dev, "Probe\n");
> +	return 0;
> +}
> +
> +static void gs_usb_disconnect(struct usb_interface *intf)
> +{
> +	unsigned i;
> +	struct gs_usb *dev = usb_get_intfdata(intf);
> +	usb_set_intfdata(intf, NULL);
> +
> +	if (!dev) {
> +		dev_err(&intf->dev, "Disconnect (nodata)\n");
> +		return;
> +	}
> +
> +	for (i = 0; i < MAX_INTF; i++) {
> +		struct gs_can *can = dev->canch[i];
> +
> +		if (!can)
> +			continue;
> +
> +		gs_destroy_candev(can);
> +	}
> +
> +	usb_kill_anchored_urbs(&dev->rx_submitted);
> +}
> +
> +MODULE_DEVICE_TABLE(usb, gs_usb_table);
> +
> +static struct usb_device_id gs_usb_table[] = {
> +	{USB_DEVICE(USB_GSUSB_1_VENDOR_ID, USB_GSUSB_1_PRODUCT_ID)},
> +	{} /* Terminating entry */
> +};
> +
> +static struct usb_driver gs_usb_driver = {
> +	.name       = "gs_usb",
> +	.probe      = gs_usb_probe,
> +	.disconnect = gs_usb_disconnect,
> +	.id_table   = gs_usb_table
> +};
> +
> +static int __init gs_usb_init(void)
> +{
> +	return usb_register(&gs_usb_driver);
> +}
> +
> +static void __exit gs_usb_exit(void)
> +{
> +	usb_deregister(&gs_usb_driver);
> +}
> +
> +module_init(gs_usb_init);
> +module_exit(gs_usb_exit);
> +
> +MODULE_AUTHOR("Maximilian Schneider <mws@schneidersoft.net>");
> +MODULE_DESCRIPTION(
> +"Socket CAN device driver for Geschwister Schneider Technologie-, "
> +"Entwicklungs- und Vertriebs UG. USB2.0 to CAN interfaces.");
> +MODULE_LICENSE("GPL v2");
> +

Thanks for your patience.

Wolfgang.

Re: GS_USB

[Max S.]

Hi Wolfgang,

On Sun, 2013-11-10 at 00:19 +0100, Wolfgang Grandegger wrote:

> You redefine the CAN flags and mask here but in many places you
> silentely assume that they are identical, e.g. via:
> 
>    cf->can_id = hf->can_id;
> 
> Not sure how to handle this transprently. I think these defines will
> never change. Either use the CAN flags and mask directly (like you
> already do for the error frames) or properly remap/copy all flags and
> values. Other opinions?

I have removed the GS_CAN_* flags. They are the same as those in the
Linux can headers. The idea was not to have to repackage everything. But
instead get by with some copies. like cf->can_id = hf->can_id; Byte
order is handled by the device.

> In case of bus-off. What does the hardware do? How does it recover? Is
> recovery triggered by software possible? Is it possible to support
> manual recovery?

Manual recovery is not supported. The node can leave bus off state if
it detects 128 occurrences of 11 consecutive recessive bits on the bus.
Maybe I can trick the controller out of bus off by doing a software
reset. That's probably not going to be a clean solution though.

> 
> > +	} else if (cf->can_id & CAN_ERR_CRTL) {
> > +		dev->can.state = CAN_STATE_ERROR_ACTIVE;
> 
> 
> This means back to error active, right?
Yes, if none of the following conditions apply.
I guess i could use an if else if else instead of conditionally
overwriting the state...
> 
> > +		if ((cf->data[1] & CAN_ERR_CRTL_TX_WARNING) ||
> > +			(cf->data[1] & CAN_ERR_CRTL_RX_WARNING))
> > +			dev->can.state = CAN_STATE_ERROR_WARNING;
> > +
> > +		if ((cf->data[1] & CAN_ERR_CRTL_TX_PASSIVE) ||
> > +			(cf->data[1]&CAN_ERR_CRTL_RX_PASSIVE))
> 
> s/&/ & /
> 
> > +			dev->can.state = CAN_STATE_ERROR_PASSIVE;
> > +	}
> 
> Also please update the stats accordingly:
These are simple counts for how often the conditions occurred? They
count when the respective state is entered? When a node recovers from
bus off does that count as entering error passive?
> 
> 	can_stats.bus_off++;
> 	can_stats.error_warning++
> 	can_stats.error_passive++
> 
> Apart from that, the state handling is rather basic but totaly
> sufficient. Would be nice if you could show the state handling
> and bus-off recovery by reporting the output of "$ candump -td -e
> any,0:0,#FFFFFFFF" while sending messages to the device ...
> 
> 1. without cable connected (entering error passive)
> 2. with short-circuited CAN high and low (entering bus-off)

$ sudo ip link set can0 up type can bitrate 250000
$ cansequence can0 -p
$ candump -td -e can0,0:0,#FFFFFFFF 1>can.log

# CAN node transmitting normally
 (000.000000)  can0  002   [1]  00
...
 (000.000006)  can0  002   [1]  68
# CAN node is disconnected from bus
 (000.040973)  can0  20000004   [8]  00 20 00 00 00 00 80 00
ERRORFRAME
	controller-problem{tx-error-passive}
	error-counter-tx-rx{{128}{0}}
 (007.437011)  can0  002   [1]  69
...
 (000.000991)  can0  002   [1]  B3
# CAN node is reconnected to bus
 (000.000008)  can0  20000004   [8]  00 00 00 00 00 00 00 00
ERRORFRAME
	controller-problem{}
 (000.000004)  can0  002   [1]  B4
...
 (000.000003)  can0  002   [1]  D3
# CAN node is disconnected from bus
 (000.062975)  can0  20000004   [8]  00 20 00 00 00 00 80 00
ERRORFRAME
	controller-problem{tx-error-passive}
	error-counter-tx-rx{{128}{0}}
# short added between CAN-High to CAN-Low
 (005.593023)  can0  20000040   [8]  00 00 00 00 00 00 00 0E
ERRORFRAME
	bus-off
	error-counter-tx-rx{{0}{14}}
 (000.260982)  can0  20000100   [8]  00 00 00 00 00 00 E8 00
ERRORFRAME
	restarted-after-bus-off
	error-counter-tx-rx{{232}{0}}
 (000.526024)  can0  20000040   [8]  00 00 00 00 00 00 00 7D
ERRORFRAME
	bus-off
	error-counter-tx-rx{{0}{125}}
 (001.834994)  can0  20000100   [8]  00 00 00 00 00 00 F0 00
ERRORFRAME
	restarted-after-bus-off
	error-counter-tx-rx{{240}{0}}
 (000.523992)  can0  20000040   [8]  00 00 00 00 00 00 00 80
ERRORFRAME
	bus-off
	error-counter-tx-rx{{0}{128}}
 (001.835013)  can0  20000100   [8]  00 00 00 00 00 00 F8 00
ERRORFRAME
	restarted-after-bus-off
	error-counter-tx-rx{{248}{0}}
 (000.524981)  can0  20000004   [8]  00 00 00 00 00 00 28 00
ERRORFRAME
	controller-problem{}
	error-counter-tx-rx{{40}{0}}
 (000.086006)  can0  20000040   [8]  00 00 00 00 00 00 00 7C
ERRORFRAME
	bus-off
	error-counter-tx-rx{{0}{124}}
# The short between CAN-High and CAN-Low is removed
 (000.525000)  can0  20000100   [8]  00 00 00 00 00 00 80 00
ERRORFRAME
	restarted-after-bus-off
	error-counter-tx-rx{{128}{0}}
 (002.702998)  can0  002   [1]  D4
...
 (000.000003)  can0  002   [1]  ED
# CAN node is reconnected to bus
 (000.000007)  can0  20000004   [8]  00 08 00 00 00 00 6E 00
ERRORFRAME
	controller-problem{tx-error-warning}
	error-counter-tx-rx{{110}{0}}
 (000.000003)  can0  002   [1]  EE
...
 (000.000990)  can0  002   [1]  60
 (000.000008)  can0  20000004   [8]  00 00 00 00 00 00 00 00
ERRORFRAME
	controller-problem{}
 (000.000004)  can0  002   [1]  61
 (000.000004)  can0  002   [1]  62
...

Thank you for your time,
Max Schneider.

Re: GS_USB

[Wolfgang Grandegger]

Hi Max,



On Mon, 11 Nov 2013 02:10:35 +0000, "Max S." <max@schneidersoft.net>

wrote:

> Hi Wolfgang,

> 

> On Sun, 2013-11-10 at 00:19 +0100, Wolfgang Grandegger wrote:

> 

>> You redefine the CAN flags and mask here but in many places you

>> silentely assume that they are identical, e.g. via:

>> 

>>    cf->can_id = hf->can_id;

>> 

>> Not sure how to handle this transprently. I think these defines will

>> never change. Either use the CAN flags and mask directly (like you

>> already do for the error frames) or properly remap/copy all flags and

>> values. Other opinions?

> 

> I have removed the GS_CAN_* flags. They are the same as those in the

> Linux can headers. The idea was not to have to repackage everything. But

> instead get by with some copies. like cf->can_id = hf->can_id; Byte

> order is handled by the device.



OK, Please add a few lines of documentation explaining that. Would be nice

to have a global version number for the current definitions and

declarations.



>> In case of bus-off. What does the hardware do? How does it recover? Is

>> recovery triggered by software possible? Is it possible to support

>> manual recovery?

> 

> Manual recovery is not supported. The node can leave bus off state if

> it detects 128 occurrences of 11 consecutive recessive bits on the bus.

> Maybe I can trick the controller out of bus off by doing a software

> reset. That's probably not going to be a clean solution though.



Would be nice if manual recovery is supported but it's not a requirement.

Maybe you could make the delay before restarting bus-off configurable

using the "restart-ms" argument.



For further information have a look to:



http://lxr.free-electrons.com/source/Documentation/networking/can.txt#L891



>> 

>> > +	} else if (cf->can_id & CAN_ERR_CRTL) {

>> > +		dev->can.state = CAN_STATE_ERROR_ACTIVE;

>> 

>> 

>> This means back to error active, right?

> Yes, if none of the following conditions apply.

> I guess i could use an if else if else instead of conditionally

> overwriting the state...

>> 

>> > +		if ((cf->data[1] & CAN_ERR_CRTL_TX_WARNING) ||

>> > +			(cf->data[1] & CAN_ERR_CRTL_RX_WARNING))

>> > +			dev->can.state = CAN_STATE_ERROR_WARNING;

>> > +

>> > +		if ((cf->data[1] & CAN_ERR_CRTL_TX_PASSIVE) ||

>> > +			(cf->data[1]&CAN_ERR_CRTL_RX_PASSIVE))

>> 

>> s/&/ & /

>> 

>> > +			dev->can.state = CAN_STATE_ERROR_PASSIVE;

>> > +	}

>> 

>> Also please update the stats accordingly:

> These are simple counts for how often the conditions occurred? They

> count when the respective state is entered? When a node recovers from

> bus off does that count as entering error passive?



Yes, if it's reported, but normally not. Currently we mainly support

increasing CAN error states active->warning->passive->bus-off.



>> 

>> 	can_stats.bus_off++;

>> 	can_stats.error_warning++

>> 	can_stats.error_passive++



I forgot "can_stats.restarts".



>> 

>> Apart from that, the state handling is rather basic but totaly

>> sufficient. Would be nice if you could show the state handling

>> and bus-off recovery by reporting the output of "$ candump -td -e

>> any,0:0,#FFFFFFFF" while sending messages to the device ...

>> 

>> 1. without cable connected (entering error passive)

>> 2. with short-circuited CAN high and low (entering bus-off)

> 

> $ sudo ip link set can0 up type can bitrate 250000

> $ cansequence can0 -p

> $ candump -td -e can0,0:0,#FFFFFFFF 1>can.log

> 

> # CAN node transmitting normally

>  (000.000000)  can0  002   [1]  00

> ...

>  (000.000006)  can0  002   [1]  68

> # CAN node is disconnected from bus

>  (000.040973)  can0  20000004   [8]  00 20 00 00 00 00 80 00

> ERRORFRAME

> 	controller-problem{tx-error-passive}

> 	error-counter-tx-rx{{128}{0}}



OK, error warning is obviously not reported (also not required).



>  (007.437011)  can0  002   [1]  69

> ...

>  (000.000991)  can0  002   [1]  B3

> # CAN node is reconnected to bus

>  (000.000008)  can0  20000004   [8]  00 00 00 00 00 00 00 00

> ERRORFRAME

> 	controller-problem{}



This is obviously the back to error active. Could you use



    cf->can_id |= CAN_ERR_PROT;

    cf->data[2] = CAN_ERR_PROT_ACTIVE;



as for the at91_can (or flexcan, c_can, usb_8dev.c). See:



http://lxr.free-electrons.com/source/drivers/net/can/at91_can.c#L962



Well, back to error active is not an error but that's how we handle

it currently.



>  (000.000004)  can0  002   [1]  B4

> ...

>  (000.000003)  can0  002   [1]  D3

> # CAN node is disconnected from bus

>  (000.062975)  can0  20000004   [8]  00 20 00 00 00 00 80 00

> ERRORFRAME

> 	controller-problem{tx-error-passive}

> 	error-counter-tx-rx{{128}{0}}

> # short added between CAN-High to CAN-Low

>  (005.593023)  can0  20000040   [8]  00 00 00 00 00 00 00 0E

> ERRORFRAME

> 	bus-off

> 	error-counter-tx-rx{{0}{14}}



The error counter do not match. Also error warning and passive

are not reported.



>  (000.260982)  can0  20000100   [8]  00 00 00 00 00 00 E8 00

> ERRORFRAME

> 	restarted-after-bus-off

> 	error-counter-tx-rx{{232}{0}}



Bus-off recovery is restarted after 26ms. Is this value configurable.

See also my comments above.



>  (000.526024)  can0  20000040   [8]  00 00 00 00 00 00 00 7D

> ERRORFRAME

> 	bus-off

> 	error-counter-tx-rx{{0}{125}}

>  (001.834994)  can0  20000100   [8]  00 00 00 00 00 00 F0 00

> ERRORFRAME

> 	restarted-after-bus-off

> 	error-counter-tx-rx{{240}{0}}

>  (000.523992)  can0  20000040   [8]  00 00 00 00 00 00 00 80

> ERRORFRAME

> 	bus-off

> 	error-counter-tx-rx{{0}{128}}

>  (001.835013)  can0  20000100   [8]  00 00 00 00 00 00 F8 00

> ERRORFRAME

> 	restarted-after-bus-off

> 	error-counter-tx-rx{{248}{0}}

>  (000.524981)  can0  20000004   [8]  00 00 00 00 00 00 28 00

> ERRORFRAME

> 	controller-problem{}

> 	error-counter-tx-rx{{40}{0}}

>  (000.086006)  can0  20000040   [8]  00 00 00 00 00 00 00 7C

> ERRORFRAME

> 	bus-off

> 	error-counter-tx-rx{{0}{124}}

> # The short between CAN-High and CAN-Low is removed

>  (000.525000)  can0  20000100   [8]  00 00 00 00 00 00 80 00

> ERRORFRAME

> 	restarted-after-bus-off

> 	error-counter-tx-rx{{128}{0}}

>  (002.702998)  can0  002   [1]  D4

> ...

>  (000.000003)  can0  002   [1]  ED

> # CAN node is reconnected to bus

>  (000.000007)  can0  20000004   [8]  00 08 00 00 00 00 6E 00

> ERRORFRAME

> 	controller-problem{tx-error-warning}

> 	error-counter-tx-rx{{110}{0}}

>  (000.000003)  can0  002   [1]  EE

> ...

>  (000.000990)  can0  002   [1]  60

>  (000.000008)  can0  20000004   [8]  00 00 00 00 00 00 00 00

> ERRORFRAME

> 	controller-problem{}



Back to error active. See my comments above. Overall, it does

not look too bad.



Wolfgang

Re: GS_USB

[Oliver Hartkopp]

>> Manual recovery is not supported. The node can leave bus off state if
> 
>> it detects 128 occurrences of 11 consecutive recessive bits on the bus.
> 
>> Maybe I can trick the controller out of bus off by doing a software
> 
>> reset. That's probably not going to be a clean solution though.
> 
> 
> 
> Would be nice if manual recovery is supported but it's not a requirement.
> 
> Maybe you could make the delay before restarting bus-off configurable
> 
> using the "restart-ms" argument.
> 
> 
> 
> For further information have a look to:
> 
> 
> 
> http://lxr.free-electrons.com/source/Documentation/networking/can.txt#L891
> 
> 

Yes.

Usually the CAN controller sits in BUS_OFF until it detects correct CAN frames
_or_ until the controller is re-initialized.

The CAN controller should not recover itself as this might be wrong depending
on the use-case.

Therefore the manual "restart" can be initiated by some user application or it
can be handled inside the driver e.g. 200ms after a BUS_OFF detection by the
"restart-ms" option.

Regards,
Oliver

Re: GS_USB

[Oliver Hartkopp]

On 11.11.2013 20:49, Max S. wrote:
> Hmm. Seems I missed something.
> 


>>>
>>> http://lxr.free-electrons.com/source/Documentation/networking/can.txt#L891
>>>
>>>
>>
>> Yes.
>>
>> Usually the CAN controller sits in BUS_OFF until it detects correct CAN frames
>> _or_ until the controller is re-initialized.
> 
> From the CAN2.0A spec chapter 7
> 12. An node which is ’bus off’ is permitted to become ’error active’ (no
> longer ’bus off’) with its error counters both set to 0 after 128
> occurrence of 11 consecutive ’recessive’ bits have been monitored on the
> bus.

Hm - I assume this does not mean 128*11 bits but 128 occurences of 11
consecutive ’recessive’ bits with at least one dominant bit in between.
But I'm not sure about that.

> 
> So: When the controller goes into bus off because of a short on can high
> to low. It will inevitably observe recessive bits. and consequently come
> back out of bus off. It will then attempt to resend and hit bus off
> again. rinse & repeat.


> 
> Why is it necessary to be able to get the controller out of bus off
> manually?

Think about a misconfigured bitrate.
The application should decide if it's better to stay calm (in BUS_OFF) or
whether it should try to re-initialize the CAN controller and start again.

> 
> I was able to improve the firmware to make status updates faster.
> The following is the current state: @250K bitrate
>  (000.000011)  can0  20000040   [8]  00 00 00 00 00 00 00 01  ERRORFRAME
> 	bus-off
> 	error-counter-tx-rx{{0}{1}}
>  (000.005980)  can0  20000100   [8]  00 00 00 00 00 00 00 80  ERRORFRAME
> 	restarted-after-bus-off
> 	error-counter-tx-rx{{0}{128}}
>  (000.000013)  can0  20000008   [8]  00 00 40 00 00 00 00 00  ERRORFRAME
> 	protocol-violation{{back-to-error-active}{}}
>  (000.000006)  can0  20000004   [8]  00 08 00 00 00 00 60 00  ERRORFRAME
> 	controller-problem{tx-error-warning}
> 	error-counter-tx-rx{{96}{0}}
>  (000.000008)  can0  20000004   [8]  00 20 00 00 00 00 80 00  ERRORFRAME
> 	controller-problem{tx-error-passive}
> 	error-counter-tx-rx{{128}{0}}
>  (000.002014)  can0  20000040   [8]  00 00 00 00 00 00 00 01  ERRORFRAME
> 	bus-off
> 	error-counter-tx-rx{{0}{1}}
> 
>>
>> The CAN controller should not recover itself as this might be wrong depending
>> on the use-case.
> 
> Is recovery (getting out of bus off) not part of the CAN spec?

As discussed above the controller get's out of the BUS_OFF state when
receiving correct CAN traffic.

Or by kicking the controller by restarting it :-)

> 
>>
>> Therefore the manual "restart" can be initiated by some user application or it
>> can be handled inside the driver e.g. 200ms after a BUS_OFF detection by the
>> "restart-ms" option.
>>

Regards,
Oliver

Re: GS_USB

[Max S.]

Hello all,

I've been doing some more testing and came across some strange behavior.
Frames appear to be out of order.

I have both chanels of the GS_USB device and a PEAKUSB adapter on a bus,
as well as another node (to ack frames).

I have modified the GS_USB firmware to PANIC when txed frames are out of
sequence.

tx interrupt now looks something like this

static uint8_t count = 0;
void tx_channel_0_interrupt(void){
	PANIC(txframe.data[0] != count);
	count++;

The GS_SUB device never panics, however cansequence -r on the peak
device gives me messages like:

received wrong sequence count. expected: 216, got: 220
received wrong sequence count. expected: 224, got: 216
received wrong sequence count. expected: 220, got: 224
received wrong sequence count. expected: 227, got: 229
received wrong sequence count. expected: 233, got: 227
received wrong sequence count. expected: 229, got: 233

notice that no frames are lost, just rearranged.

I can force frames to be out of order by restarting cansequence, so i
know my monitor code is working.

I have been trying to reproduce this error using libusb in userspace,
but have not had any success.

Any thoughts on this?

Regards,
Max Schneider.

Re: GS_USB

[Max S.]

OK.

Here's the latest progress.

no line wrap this time :)

From 74b99fe4e949a53d05ac35dc413e3ec3f9e352f6 Mon Sep 17 00:00:00 2001
From: Maximilian Schneider <max@schneidersoft.net>
Date: Sun, 3 Nov 2013 16:57:06 +0000
Subject: [PATCH] Added support for the GS_USB CAN devices. The Geschwister
 Schneider Family of devices are galvanically isolated
 USB2.0 to CAN2.0A/B adapters. Currently two form factors
 are available, a tethered dongle in a rugged enclosure, and
 mini-pci-e card.


Signed-off-by: Maximilian Schneider <max@schneidersoft.net>
---
 drivers/net/can/usb/Kconfig  |    8 +
 drivers/net/can/usb/Makefile |    1 +
 drivers/net/can/usb/gs_usb.c | 1005 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 1014 insertions(+)
 create mode 100644 drivers/net/can/usb/gs_usb.c

diff --git a/drivers/net/can/usb/Kconfig b/drivers/net/can/usb/Kconfig
index fc96a3d..f5e3e8c 100644
--- a/drivers/net/can/usb/Kconfig
+++ b/drivers/net/can/usb/Kconfig
@@ -54,4 +54,12 @@ config CAN_8DEV_USB
 	  This driver supports the USB2CAN interface
 	  from 8 devices (http://www.8devices.com).
 
+config CAN_GS_USB
+	tristate "Geschwister Schneider UG interfaces"
+	---help---
+	  This driver supports the Geschwister Schneider USB/CAN devices.
+	  If unsure choose N,
+	  choose Y for built in support,
+	  M to compile as module (module will be named: gs_usb).
+
 endmenu
diff --git a/drivers/net/can/usb/Makefile b/drivers/net/can/usb/Makefile
index becef46..c21a521 100644
--- a/drivers/net/can/usb/Makefile
+++ b/drivers/net/can/usb/Makefile
@@ -7,5 +7,6 @@ obj-$(CONFIG_CAN_ESD_USB2) += esd_usb2.o
 obj-$(CONFIG_CAN_KVASER_USB) += kvaser_usb.o
 obj-$(CONFIG_CAN_PEAK_USB) += peak_usb/
 obj-$(CONFIG_CAN_8DEV_USB) += usb_8dev.o
+obj-$(CONFIG_CAN_GS_USB) += gs_usb.o
 
 ccflags-$(CONFIG_CAN_DEBUG_DEVICES) := -DDEBUG
diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
new file mode 100644
index 0000000..732f3cf
--- /dev/null
+++ b/drivers/net/can/usb/gs_usb.c
@@ -0,0 +1,1005 @@
+/* CAN driver for Geschwister Schneider USB/CAN devices.
+ *
+ * Copyright (C) 2013 Geschwister Schneider Technologie-,
+ * Entwicklungs- und Vertriebs UG (Haftungsbeschränkt).
+ *
+ * Many thanks to all socketcan devs!
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published
+ * by the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/init.h>
+#include <linux/signal.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/usb.h>
+
+#include <linux/can.h>
+#include <linux/can/dev.h>
+#include <linux/can/error.h>
+
+/* Device specific constants */
+#define USB_GSUSB_1_VENDOR_ID      0x1d50
+#define USB_GSUSB_1_PRODUCT_ID     0x606f
+
+#define GSUSB_ENDPOINT_IN          1
+#define GSUSB_ENDPOINT_OUT         2
+
+/* Device specific constants */
+enum gs_usb_breq {
+	GS_USB_BREQ_HOST_FORMAT = 0,
+	GS_USB_BREQ_BITTIMING,
+	GS_USB_BREQ_MODE,
+	GS_USB_BREQ_BERR,
+	GS_USB_BREQ_BT_CONST,
+	GS_USB_BREQ_DEVICE_CONFIG
+};
+
+enum gs_can_mode {
+	/* reset a channel. turns it off */
+	GS_CAN_MODE_RESET = 0,
+	/* starts a channel */
+	GS_CAN_MODE_START
+};
+
+enum gs_can_state {
+	GS_CAN_STATE_ERROR_ACTIVE = 0,
+	GS_CAN_STATE_ERROR_WARNING,
+	GS_CAN_STATE_ERROR_PASSIVE,
+	GS_CAN_STATE_BUS_OFF,
+	GS_CAN_STATE_STOPPED,
+	GS_CAN_STATE_SLEEPING
+};
+
+/* data types passed between host and device */
+struct gs_host_config {
+	u32 byte_order;
+} __packed;
+
+struct gs_device_config {
+	u8 reserved1;
+	u8 reserved2;
+	u8 reserved3;
+	u8 icount;
+	u32 sw_version;
+	u32 hw_version;
+} __packed;
+
+#define GS_CAN_MODE_NORMAL               0
+#define GS_CAN_MODE_LISTEN_ONLY          (1<<0)
+#define GS_CAN_MODE_LOOP_BACK            (1<<1)
+#define GS_CAN_MODE_TRIPLE_SAMPLE        (1<<2)
+#define GS_CAN_MODE_ONE_SHOT             (1<<3)
+
+struct gs_device_mode {
+	u32 mode;
+	u32 flags;
+} __packed;
+
+struct gs_device_state {
+	u32 state;
+	u32 rxerr;
+	u32 txerr;
+} __packed;
+
+struct gs_device_bittiming {
+	u32 prop_seg;
+	u32 phase_seg1;
+	u32 phase_seg2;
+	u32 sjw;
+	u32 brp;
+} __packed;
+
+#define GS_CAN_FEATURE_LISTEN_ONLY      (1<<0)
+#define GS_CAN_FEATURE_LOOP_BACK        (1<<1)
+#define GS_CAN_FEATURE_TRIPLE_SAMPLE    (1<<2)
+#define GS_CAN_FEATURE_ONE_SHOT         (1<<3)
+
+struct gs_device_bt_const {
+	u32 feature;
+	u32 fclk_can;
+	u32 tseg1_min;
+	u32 tseg1_max;
+	u32 tseg2_min;
+	u32 tseg2_max;
+	u32 sjw_max;
+	u32 brp_min;
+	u32 brp_max;
+	u32 brp_inc;
+} __packed;
+
+#define GS_CAN_FLAG_OVERFLOW 1
+
+struct gs_host_frame {
+	u32 echo_id;
+	u32 can_id;
+
+	u8 can_dlc;
+	u8 channel;
+	u8 flags;
+	u8 reserved;
+
+	u8 data[8];
+} __packed;
+
+/* Only send a max of GS_MAX_TX_URBS frames per channel at a time. */
+#define GS_MAX_TX_URBS 10
+/* Only launch a max of GS_MAX_RX_URBS usb requests at a time. */
+#define GS_MAX_RX_URBS 30
+/* Maximum number of interfaces the driver supports per device.
+ * Current hardware only supports 2 interfaces. The future may vary.
+ */
+#define GS_MAX_INTF 2
+
+struct gs_tx_context {
+	struct gs_can *dev;
+	unsigned int echo_id;
+};
+
+struct gs_can {
+	struct can_priv can; /* must be the first member */
+
+	struct gs_usb *parent;
+
+	struct net_device *netdev;
+	struct usb_device *udev;
+	struct usb_interface *iface;
+
+	struct can_bittiming_const bt_const;
+	unsigned int channel;	/* channel number */
+
+	/* This lock prevents a race condition between xmit and recieve. */
+	spinlock_t tx_ctx_lock;
+	struct gs_tx_context tx_context[GS_MAX_TX_URBS];
+
+	struct usb_anchor tx_submitted;
+	atomic_t active_tx_urbs;
+};
+
+/* usb interface struct */
+struct gs_usb {
+	struct gs_can *canch[GS_MAX_INTF];
+	struct usb_anchor rx_submitted;
+	atomic_t active_channels;
+	struct usb_device *udev;
+};
+
+/* 'allocate' a tx context.
+ * returns a valid tx context or NULL if there is no space.
+ */
+static struct gs_tx_context *gs_alloc_tx_context(struct gs_can *dev)
+{
+	int i = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->tx_ctx_lock, flags);
+
+	for (; i < GS_MAX_TX_URBS; i++) {
+		if (dev->tx_context[i].echo_id == GS_MAX_TX_URBS) {
+			dev->tx_context[i].echo_id = i;
+			spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
+			return &dev->tx_context[i];
+		}
+	}
+
+	spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
+	return NULL;
+}
+
+/* releases a tx context
+ */
+static void gs_free_tx_context(struct gs_tx_context *txc)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&txc->dev->tx_ctx_lock, flags);
+	txc->echo_id = GS_MAX_TX_URBS;
+	spin_unlock_irqrestore(&txc->dev->tx_ctx_lock, flags);
+}
+
+/* Get a tx context by id.
+ */
+static struct gs_tx_context *gs_get_tx_context(
+	struct gs_can *dev,
+	unsigned int id)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->tx_ctx_lock, flags);
+	if (id < GS_MAX_TX_URBS) {
+		if (dev->tx_context[id].echo_id == id) {
+			spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
+			return &dev->tx_context[id];
+		}
+	}
+	spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
+	return NULL;
+}
+
+/* Get a tx contexts id.
+ */
+static unsigned int gs_tx_context_id(struct gs_tx_context *txc)
+{
+	unsigned int id;
+	id = txc->echo_id;
+	return id;
+}
+
+static int gs_cmd_reset(struct gs_usb *gsusb, struct gs_can *gsdev)
+{
+	struct gs_device_mode *dm;
+	struct usb_interface *intf = gsdev->iface;
+	int rc;
+
+	dm = kzalloc(sizeof(*dm), GFP_KERNEL);
+	if (!dm)
+		return -ENOMEM;
+
+	dm->mode = GS_CAN_MODE_RESET;
+
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_MODE,
+			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			gsdev->channel,
+			0,
+			dm,
+			sizeof(*dm),
+			1000);
+
+	return rc;
+}
+
+static void gs_update_state(struct gs_can *dev, struct can_frame *cf)
+{
+	struct can_device_stats *can_stats = &dev->can.can_stats;
+
+	if (cf->can_id & CAN_ERR_RESTARTED) {
+		dev->can.state = CAN_STATE_ERROR_ACTIVE;
+		can_stats->restarts++;
+	} else if (cf->can_id & CAN_ERR_BUSOFF) {
+		dev->can.state = CAN_STATE_BUS_OFF;
+		can_stats->bus_off++;
+	} else if (cf->can_id & CAN_ERR_CRTL) {
+		if ((cf->data[1] & CAN_ERR_CRTL_TX_WARNING) ||
+			(cf->data[1] & CAN_ERR_CRTL_RX_WARNING)) {
+			dev->can.state = CAN_STATE_ERROR_WARNING;
+			can_stats->error_warning++;
+		} else if ((cf->data[1] & CAN_ERR_CRTL_TX_PASSIVE) ||
+			(cf->data[1] & CAN_ERR_CRTL_RX_PASSIVE)) {
+			dev->can.state = CAN_STATE_ERROR_PASSIVE;
+			can_stats->error_passive++;
+		} else {
+			dev->can.state = CAN_STATE_ERROR_ACTIVE;
+		}
+	}
+}
+
+static void gs_usb_recieve_bulk_callback(struct urb *urb)
+{
+	struct gs_usb *usbcan = urb->context;
+	struct gs_can *dev;
+	struct net_device *netdev;
+	int rc;
+	struct net_device_stats *stats;
+	struct gs_host_frame *hf = urb->transfer_buffer;
+	struct gs_tx_context *txc;
+	struct can_frame *cf;
+	struct sk_buff *skb;
+
+	BUG_ON(!usbcan);
+
+	switch (urb->status) {
+	case 0: /* success */
+		break;
+	case -ENOENT:
+	case -ESHUTDOWN:
+		return;
+	default:
+		/* do not resubmit aborted urbs. eg: when device goes down */
+		return;
+	}
+
+	/* device reports out of range channel id */
+	if (hf->channel >= GS_MAX_INTF)
+		goto resubmit_urb;
+
+	/* device reports bad channel id */
+	dev = usbcan->canch[hf->channel];
+
+	netdev = dev->netdev;
+	stats = &netdev->stats;
+
+	if (!netif_device_present(netdev))
+		return;
+
+	if (hf->echo_id == -1) { /* normal rx */
+		skb = alloc_can_skb(dev->netdev, &cf);
+		if (skb == NULL)
+			return;
+
+		cf->can_id = hf->can_id;
+		/* is it necessary to use get_can_dlc? */
+		cf->can_dlc = get_can_dlc(hf->can_dlc);
+		memcpy(cf->data, hf->data, 8);
+
+		/* ERROR frames tell us information about the controller */
+		if (hf->can_id & CAN_ERR_FLAG)
+			gs_update_state(dev, cf);
+
+		netif_rx(skb);
+
+		netdev->stats.rx_packets++;
+		netdev->stats.rx_bytes += hf->can_dlc;
+	} else { /* echo_id == hf->echo_id */
+		if (hf->echo_id >= GS_MAX_TX_URBS) {
+			netdev_err(netdev,
+				"Device sent an out of range echo id %d\n",
+				hf->echo_id);
+			goto resubmit_urb;
+		}
+
+		netdev->stats.tx_packets++;
+		netdev->stats.tx_bytes += hf->can_dlc;
+
+		txc = gs_get_tx_context(dev, hf->echo_id);
+
+		/* bad devices send bad echo_ids. */
+		if (!txc) {
+			netdev_err(netdev,
+				"Device sent a bad echo id %d\n",
+				hf->echo_id);
+			goto resubmit_urb;
+		}
+
+		can_get_echo_skb(netdev, gs_tx_context_id(txc));
+
+		gs_free_tx_context(txc);
+
+		netif_wake_queue(netdev);
+	}
+
+	if (hf->flags & GS_CAN_FLAG_OVERFLOW) {
+		skb = alloc_can_err_skb(netdev, &cf);
+		if (skb == NULL)
+			goto resubmit_urb;
+
+		cf->can_id |= CAN_ERR_CRTL;
+		cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
+		stats->rx_over_errors++;
+		stats->rx_errors++;
+		netif_rx(skb);
+	}
+
+resubmit_urb:
+	/* note: no urb refill... works for me */
+	usb_fill_bulk_urb(urb,
+			usbcan->udev,
+			usb_rcvbulkpipe(usbcan->udev, GSUSB_ENDPOINT_IN),
+			hf,
+			sizeof(struct gs_host_frame),
+			gs_usb_recieve_bulk_callback,
+			usbcan
+			);
+
+	rc = usb_submit_urb(urb, GFP_ATOMIC);
+
+	/* USB failure take down all interfaces */
+	if (rc == -ENODEV) {
+		for (rc = 0; rc < GS_MAX_INTF; rc++) {
+			if (usbcan->canch[rc])
+				netif_device_detach(usbcan->canch[rc]->netdev);
+		}
+	}
+}
+
+static int gs_usb_set_bittiming(struct net_device *netdev)
+{
+	struct gs_can *dev = netdev_priv(netdev);
+	struct can_bittiming *bt = &dev->can.bittiming;
+	struct usb_interface *intf = dev->iface;
+	int rc;
+	struct gs_device_bittiming *dbt;
+
+	dbt = kmalloc(sizeof(*dbt), GFP_KERNEL);
+	if (!dbt)
+		return -ENOMEM;
+
+	dbt->prop_seg = bt->prop_seg;
+	dbt->phase_seg1 = bt->phase_seg1;
+	dbt->phase_seg2 = bt->phase_seg2;
+	dbt->sjw = bt->sjw;
+	dbt->brp = bt->brp;
+
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_BITTIMING,
+			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			dev->channel,
+			0,
+			dbt,
+			sizeof(*dbt),
+			1000);
+	if (rc < 0)
+		dev_err(netdev->dev.parent, "Couldn't set bittimings %d", rc);
+
+	kfree(dbt);
+
+	return rc;
+}
+
+static void gs_usb_xmit_callback(struct urb *urb)
+{
+	struct gs_tx_context *txc = urb->context;
+	struct gs_can *dev = txc->dev;
+	struct net_device *netdev = dev->netdev;
+
+	if (urb->status) {
+		netdev_info(netdev, "%d] xmit err %d\n",
+			dev->channel, txc->echo_id);
+	}
+
+	usb_free_coherent(urb->dev,
+		urb->transfer_buffer_length,
+		urb->transfer_buffer,
+		urb->transfer_dma);
+
+	atomic_dec(&dev->active_tx_urbs);
+
+	if (!netif_device_present(netdev))
+		return;
+
+	if (netif_queue_stopped(netdev))
+		netif_wake_queue(netdev);
+}
+
+static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
+	struct net_device *netdev)
+{
+	struct gs_can *dev = netdev_priv(netdev);
+	struct net_device_stats *stats = &dev->netdev->stats;
+	struct urb *urb;
+	struct gs_host_frame *hf;
+	struct can_frame *cf;
+	int rc;
+	unsigned int idx;
+	struct gs_tx_context *txc;
+
+	if (dev->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
+		return NETDEV_TX_BUSY;
+
+	if (can_dropped_invalid_skb(netdev, skb))
+		return NETDEV_TX_OK;
+
+	/* find an empty context to keep track of transmission */
+	txc = gs_alloc_tx_context(dev);
+	if (!txc)
+		return NETDEV_TX_BUSY;
+
+	/* create a URB, and a buffer for it */
+	urb = usb_alloc_urb(0, GFP_ATOMIC);
+	if (!urb) {
+		netdev_err(netdev, "No memory left for URBs\n");
+		goto nomem_urb;
+	}
+
+	hf = usb_alloc_coherent(dev->udev, sizeof(*hf), GFP_ATOMIC,
+		&urb->transfer_dma);
+	if (!hf) {
+		netdev_err(netdev, "No memory left for USB buffer\n");
+		goto nomem_hf;
+	}
+
+	idx = gs_tx_context_id(txc);
+
+	if (idx >= GS_MAX_TX_URBS) {
+		netdev_err(netdev, "Invalid tx context %d\n", idx);
+		goto badidx;
+	}
+
+	hf->echo_id = idx;
+	hf->channel = dev->channel;
+
+	cf = (struct can_frame *)skb->data;
+
+	hf->can_id = cf->can_id;
+	hf->can_dlc = cf->can_dlc;
+	memcpy(hf->data, cf->data, 8);
+
+	usb_fill_bulk_urb(urb, dev->udev,
+			usb_sndbulkpipe(dev->udev, GSUSB_ENDPOINT_OUT),
+			hf,
+			sizeof(*hf),
+			gs_usb_xmit_callback,
+			txc);
+
+	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+	usb_anchor_urb(urb, &dev->tx_submitted);
+
+	can_put_echo_skb(skb, netdev, idx);
+
+	atomic_inc(&dev->active_tx_urbs);
+
+	rc = usb_submit_urb(urb, GFP_ATOMIC);
+	if (unlikely(rc)) {			/* usb send failed */
+		atomic_dec(&dev->active_tx_urbs);
+
+		netdev_err(netdev, "usb_submit failed %d\n", rc);
+
+		can_free_echo_skb(netdev, gs_tx_context_id(txc));
+		gs_free_tx_context(txc);
+
+		usb_unanchor_urb(urb);
+		usb_free_coherent(dev->udev,
+			sizeof(*hf),
+			hf,
+			urb->transfer_dma);
+
+
+		if (rc == -ENODEV) {
+			netif_device_detach(netdev);
+		} else {
+			netdev_err(netdev, "Failed tx_urb %d\n", rc);
+			stats->tx_dropped++;
+		}
+	} else {
+		netdev->trans_start = jiffies;
+
+		/* Slow down tx path */
+		if (atomic_read(&dev->active_tx_urbs) >= GS_MAX_TX_URBS)
+			netif_stop_queue(netdev);
+	}
+
+	/* let usb core take care of this urb */
+	usb_free_urb(urb);
+
+	return NETDEV_TX_OK;
+
+badidx:
+	usb_free_coherent(dev->udev,
+				sizeof(*hf),
+				hf,
+				urb->transfer_dma);
+nomem_hf:
+	usb_free_urb(urb);
+
+nomem_urb:
+	gs_free_tx_context(txc);
+	dev_kfree_skb(skb);
+	stats->tx_dropped++;
+	return NETDEV_TX_OK;
+}
+
+static int gs_can_open(struct net_device *netdev)
+{
+	struct gs_can *dev = netdev_priv(netdev);
+	struct gs_usb *parent = dev->parent;
+	int rc, i;
+	struct gs_device_mode *dm;
+	u32 ctrlmode;
+
+	rc = open_candev(netdev);
+	if (rc)
+		return rc;
+
+	if (atomic_add_return(1, &parent->active_channels) == 1) {
+		for (i = 0; i < GS_MAX_RX_URBS; i++) {
+			struct urb *urb = NULL;
+			u8 *buf = NULL;
+
+			/* alloc rx urb */
+			urb = usb_alloc_urb(0, GFP_KERNEL);
+			if (!urb) {
+				netdev_err(netdev,
+					"No memory left for URBs\n");
+				return -ENOMEM;
+			}
+
+			/* alloc rx buffer */
+			buf = usb_alloc_coherent(dev->udev,
+				sizeof(struct gs_host_frame),
+				GFP_KERNEL,
+				&urb->transfer_dma);
+			if (!buf) {
+				netdev_err(netdev,
+					"No memory left for USB buffer\n");
+				usb_free_urb(urb);
+				return -ENOMEM;
+			}
+
+			/* fill, anchor, and submit rx urb */
+			usb_fill_bulk_urb(urb,
+					dev->udev,
+					usb_rcvbulkpipe(dev->udev,
+						GSUSB_ENDPOINT_IN),
+					buf,
+					sizeof(struct gs_host_frame),
+					gs_usb_recieve_bulk_callback,
+					parent
+					);
+			urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+
+			usb_anchor_urb(urb, &parent->rx_submitted);
+
+			rc = usb_submit_urb(urb, GFP_KERNEL);
+			if (rc) {
+				if (rc == -ENODEV)
+					netif_device_detach(dev->netdev);
+
+				usb_unanchor_urb(urb);
+				break;
+			}
+
+			/* Drop reference,
+			 * USB core will take care of freeing it
+			 */
+			usb_free_urb(urb);
+		}
+	}
+
+	dm = kmalloc(sizeof(*dm), GFP_KERNEL);
+	if (!dm)
+		return -ENOMEM;
+
+	/* flags */
+	ctrlmode = dev->can.ctrlmode;
+	dm->flags = 0;
+
+	if (ctrlmode & CAN_CTRLMODE_LOOPBACK)
+		dm->flags |= GS_CAN_MODE_LOOP_BACK;
+	else if (ctrlmode & CAN_CTRLMODE_LISTENONLY)
+		dm->flags |= GS_CAN_MODE_LISTEN_ONLY;
+
+	/* Controller is not allowed to retry TX
+	 * this mode is unavailable on atmels uc3c hardware
+	 */
+	if (ctrlmode & CAN_CTRLMODE_ONE_SHOT)
+		dm->flags |= GS_CAN_MODE_ONE_SHOT;
+
+	if (ctrlmode & CAN_CTRLMODE_3_SAMPLES)
+		dm->flags |= GS_CAN_MODE_TRIPLE_SAMPLE;
+
+	/* finally start device */
+	dm->mode = GS_CAN_MODE_START;
+	rc = usb_control_msg(interface_to_usbdev(dev->iface),
+			usb_sndctrlpipe(interface_to_usbdev(dev->iface), 0),
+			GS_USB_BREQ_MODE,
+			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			dev->channel,
+			0,
+			dm,
+			sizeof(*dm),
+			1000);
+
+	if (rc < 0) {
+		netdev_err(netdev, "Couldn't start device (err=%d)\n", rc);
+		kfree(dm);
+		return rc;
+	}
+
+	rc = usb_control_msg(interface_to_usbdev(dev->iface),
+			usb_rcvctrlpipe(interface_to_usbdev(dev->iface), 0),
+			GS_USB_BREQ_MODE,
+			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			dev->channel,
+			0,
+			dm,
+			sizeof(*dm),
+			1000);
+
+	if (rc < 0) {
+		netdev_err(netdev, "Couldn't get device mode (err=%d)\n",
+			rc);
+		kfree(dm);
+		return rc;
+	}
+
+	kfree(dm);
+
+	dev->can.state = CAN_STATE_ERROR_ACTIVE;
+
+	netif_start_queue(netdev);
+
+	return 0;
+}
+
+static int gs_can_close(struct net_device *netdev)
+{
+	int rc;
+	struct gs_can *dev = netdev_priv(netdev);
+	struct gs_usb *parent = dev->parent;
+
+	netif_stop_queue(netdev);
+
+	/* Stop polling */
+	if (atomic_dec_and_test(&parent->active_channels))
+		usb_kill_anchored_urbs(&parent->rx_submitted);
+
+	rc = gs_cmd_reset(parent, dev);
+
+	if (rc < 0)
+		netdev_warn(netdev, "Couldn't shutdown device (err=%d)", rc);
+
+	close_candev(netdev);
+
+	return 0;
+}
+
+/******************************** USB ********************************/
+
+static const struct net_device_ops gs_usb_netdev_ops = {
+	.ndo_open = gs_can_open,
+	.ndo_stop = gs_can_close,
+	.ndo_start_xmit = gs_can_start_xmit,
+};
+
+static struct gs_can *gs_make_candev(unsigned int channel,
+	struct usb_interface *intf)
+{
+	struct gs_can *dev;
+	struct net_device *netdev;
+	int rc;
+	struct gs_device_bt_const *bt_const;
+
+	bt_const = kmalloc(sizeof(*bt_const), GFP_KERNEL);
+	if (!bt_const)
+		return ERR_PTR(-ENOMEM);
+
+	/* fetch bit timing constants */
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_BT_CONST,
+			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			channel,
+			0,
+			bt_const,
+			sizeof(*bt_const),
+			1000);
+
+	if (rc < 0) {
+		dev_err(&intf->dev,
+			"Couldn't get bit timing const for channel (err=%d)\n",
+			rc);
+		kfree(bt_const);
+		return ERR_PTR(rc);
+	}
+
+	/* create netdev */
+	netdev = alloc_candev(sizeof(struct gs_can), GS_MAX_TX_URBS);
+	if (!netdev) {
+		dev_err(&intf->dev, "Couldn't alloc candev\n");
+		kfree(bt_const);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	dev = netdev_priv(netdev);
+
+	netdev->netdev_ops = &gs_usb_netdev_ops;
+
+	netdev->flags |= IFF_ECHO; /* we support full roundtrip echo */
+
+	/* dev settup */
+	strcpy(dev->bt_const.name, "gs_usb");
+	dev->bt_const.tseg1_min = bt_const->tseg1_min;
+	dev->bt_const.tseg1_max = bt_const->tseg1_max;
+	dev->bt_const.tseg2_min = bt_const->tseg2_min;
+	dev->bt_const.tseg2_max = bt_const->tseg2_max;
+	dev->bt_const.sjw_max = bt_const->sjw_max;
+	dev->bt_const.brp_min = bt_const->brp_min;
+	dev->bt_const.brp_max = bt_const->brp_max;
+	dev->bt_const.brp_inc = bt_const->brp_inc;
+
+	dev->udev = interface_to_usbdev(intf);
+	dev->iface = intf;
+	dev->netdev = netdev;
+	dev->channel = channel;
+
+	init_usb_anchor(&dev->tx_submitted);
+	atomic_set(&dev->active_tx_urbs, 0);
+	spin_lock_init(&dev->tx_ctx_lock);
+	for (rc = 0; rc < GS_MAX_TX_URBS; rc++) {
+		dev->tx_context[rc].dev = dev;
+		dev->tx_context[rc].echo_id = GS_MAX_TX_URBS;
+	}
+
+	/* can settup */
+	dev->can.state = CAN_STATE_STOPPED;
+	dev->can.clock.freq = bt_const->fclk_can;
+	dev->can.bittiming_const = &dev->bt_const;
+	dev->can.do_set_bittiming = gs_usb_set_bittiming;
+
+	dev->can.ctrlmode_supported = 0;
+
+	if (bt_const->feature & GS_CAN_FEATURE_LISTEN_ONLY)
+		dev->can.ctrlmode_supported |= CAN_CTRLMODE_LISTENONLY;
+
+	if (bt_const->feature & GS_CAN_FEATURE_LOOP_BACK)
+		dev->can.ctrlmode_supported |= CAN_CTRLMODE_LOOPBACK;
+
+	if (bt_const->feature & GS_CAN_FEATURE_TRIPLE_SAMPLE)
+		dev->can.ctrlmode_supported |= CAN_CTRLMODE_3_SAMPLES;
+
+	if (bt_const->feature & GS_CAN_FEATURE_ONE_SHOT)
+		dev->can.ctrlmode_supported |= CAN_CTRLMODE_ONE_SHOT;
+
+	kfree(bt_const);
+
+	SET_NETDEV_DEV(netdev, &intf->dev);
+
+	rc = register_candev(dev->netdev);
+	if (rc) {
+		free_candev(dev->netdev);
+		dev_err(&intf->dev, "Couldn't register candev\n");
+		return ERR_PTR(rc);
+	}
+
+	return dev;
+}
+
+static void gs_destroy_candev(struct gs_can *dev)
+{
+	unregister_candev(dev->netdev);
+	free_candev(dev->netdev);
+	usb_kill_anchored_urbs(&dev->tx_submitted);
+}
+
+static int gs_usb_probe(struct usb_interface *intf,
+	const struct usb_device_id *id)
+{
+	struct gs_usb *dev;
+	int rc = -ENOMEM;
+	unsigned int icount, i;
+	struct gs_host_config *hconf;
+	struct gs_device_config *dconf;
+
+	hconf = kmalloc(sizeof(*hconf), GFP_KERNEL);
+	if (!hconf)
+		return -ENOMEM;
+
+	hconf->byte_order = 0x0000beef;
+
+	/* send host config */
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_HOST_FORMAT,
+			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			1,
+			intf->altsetting[0].desc.bInterfaceNumber,
+			hconf,
+			sizeof(*hconf),
+			1000);
+
+	kfree(hconf);
+
+	if (rc < 0) {
+		dev_err(&intf->dev, "Couldn't send data format: %d\n",
+			rc);
+		return rc;
+	}
+
+
+	dconf = kmalloc(sizeof(*dconf), GFP_KERNEL);
+	if (!dconf)
+		return -ENOMEM;
+
+	/* read device config */
+	rc = usb_control_msg(interface_to_usbdev(intf),
+			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
+			GS_USB_BREQ_DEVICE_CONFIG,
+			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+			1,
+			intf->altsetting[0].desc.bInterfaceNumber,
+			dconf,
+			sizeof(*dconf),
+			1000);
+	if (rc < 0) {
+		dev_err(&intf->dev, "Couldn't recieve device config: %d\n",
+			rc);
+
+		kfree(dconf);
+
+		return rc;
+	}
+
+	icount = dconf->icount+1;
+
+	kfree(dconf);
+
+	dev_info(&intf->dev, "Configuring for %d interfaces\n", icount);
+
+	if (icount > GS_MAX_INTF) {
+		dev_err(&intf->dev,
+			"Driver cannot handle more that %d CAN interfaces\n",
+			GS_MAX_INTF);
+		return -EINVAL;
+	}
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	init_usb_anchor(&dev->rx_submitted);
+
+	atomic_set(&dev->active_channels, 0);
+
+	usb_set_intfdata(intf, dev);
+	dev->udev = interface_to_usbdev(intf);
+
+	for (i = 0; i < icount; i++) {
+		dev->canch[i] = gs_make_candev(i, intf);
+		if (IS_ERR_OR_NULL(dev->canch[i])) {
+			/* on failure destroy previously created candevs */
+			icount = i;
+			for (i = 0; i < icount; i++) {
+				gs_destroy_candev(dev->canch[i]);
+				dev->canch[icount] = NULL;
+			}
+			return rc;
+		}
+		dev->canch[i]->parent = dev;
+	}
+
+	dev_info(&intf->dev, "Probe\n");
+	return 0;
+}
+
+static void gs_usb_disconnect(struct usb_interface *intf)
+{
+	unsigned i;
+	struct gs_usb *dev = usb_get_intfdata(intf);
+	usb_set_intfdata(intf, NULL);
+
+	if (!dev) {
+		dev_err(&intf->dev, "Disconnect (nodata)\n");
+		return;
+	}
+
+	for (i = 0; i < GS_MAX_INTF; i++) {
+		struct gs_can *can = dev->canch[i];
+
+		if (!can)
+			continue;
+
+		gs_destroy_candev(can);
+	}
+
+	usb_kill_anchored_urbs(&dev->rx_submitted);
+}
+
+MODULE_DEVICE_TABLE(usb, gs_usb_table);
+
+static struct usb_device_id gs_usb_table[] = {
+	{USB_DEVICE(USB_GSUSB_1_VENDOR_ID, USB_GSUSB_1_PRODUCT_ID)},
+	{} /* Terminating entry */
+};
+
+static struct usb_driver gs_usb_driver = {
+	.name       = "gs_usb",
+	.probe      = gs_usb_probe,
+	.disconnect = gs_usb_disconnect,
+	.id_table   = gs_usb_table
+};
+
+static int __init gs_usb_init(void)
+{
+	return usb_register(&gs_usb_driver);
+}
+
+static void __exit gs_usb_exit(void)
+{
+	usb_deregister(&gs_usb_driver);
+}
+
+module_init(gs_usb_init);
+module_exit(gs_usb_exit);
+
+MODULE_AUTHOR("Maximilian Schneider <mws@schneidersoft.net>");
+MODULE_DESCRIPTION(
+"Socket CAN device driver for Geschwister Schneider Technologie-, "
+"Entwicklungs- und Vertriebs UG. USB2.0 to CAN interfaces.");
+MODULE_LICENSE("GPL v2");
+
-- 
1.7.10.4

GS_USB

[Max S.]

Hey,

Can someone give me a heads up on the GS_USB driver?

Whats the next step? Is someone looking at it?

Regards,
Max Schneider.

Re: GS_USB

[Oliver Hartkopp]

On 04.12.2013 22:17, Max S. wrote:

> Can someone give me a heads up on the GS_USB driver?
> 
> Whats the next step? Is someone looking at it?

Hello Max,

AFAIK Wolfgang asked for some comments and I'm still not sure about the
BUS_OFF behaviour.

Additionally it is usual to have an available hardware when a driver get's
into mainline. I tried to click the "Add To Cart" button at
http://schneidersoft.net/node/2 but nothing happens :-(

As long as there's no available HW there's IMHO no pressure for mainline.

Regards,
Oliver

Re: GS_USB

[Oliver Hartkopp]

On 05.12.2013 20:05, Oliver Hartkopp wrote:
> On 04.12.2013 22:17, Max S. wrote:
> 
>> Can someone give me a heads up on the GS_USB driver?
>>
>> Whats the next step? Is someone looking at it?
> 
> Hello Max,
> 
> AFAIK Wolfgang asked for some comments and I'm still not sure about the
> BUS_OFF behaviour.
> 
> Additionally it is usual to have an available hardware when a driver get's
> into mainline. I tried to click the "Add To Cart" button at
> http://schneidersoft.net/node/2 but nothing happens :-(

Oops. Now there is something :-)

Did you activate it today?

> 
> As long as there's no available HW there's IMHO no pressure for mainline.
> 
> Regards,
> Oliver
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-can" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

Re: GS_USB

[Max S.]

On Thu, 2013-12-05 at 20:07 +0100, Oliver Hartkopp wrote:
> 
> On 05.12.2013 20:05, Oliver Hartkopp wrote:
> > On 04.12.2013 22:17, Max S. wrote:
> > 
> >> Can someone give me a heads up on the GS_USB driver?
> >>
> >> Whats the next step? Is someone looking at it?
> > 
> > Hello Max,
> > 
> > AFAIK Wolfgang asked for some comments and I'm still not sure about the
> > BUS_OFF behaviour.
> > 
> > Additionally it is usual to have an available hardware when a driver get's
> > into mainline. I tried to click the "Add To Cart" button at
> > http://schneidersoft.net/node/2 but nothing happens :-(
> 
> Oops. Now there is something :-)
> 
> Did you activate it today?

Nope Its been up for a while. It requires javascript, maybe you had it
turned off?

> 
> > 
> > As long as there's no available HW there's IMHO no pressure for mainline.
> > 
> > Regards,
> > Oliver
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-can" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-can" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: GS_USB

[Wolfgang Grandegger]

Hi Max,

On 12/04/2013 10:17 PM, Max S. wrote:
> Hey,
> 
> Can someone give me a heads up on the GS_USB driver?
> 
> Whats the next step? Is someone looking at it?

I will have a final look tomorrow or over the week-end. The driver was
already in a good shape. Then it's up to Marc...

Anyway, next time please send the patch as standalone mail with the
subject "[PATCH vX] can: gs_usb: ..." incrementing X for each new
version. It's also common to briefly describe what has been changed
below the "---" line. A rather good example is here:

  http://marc.info/?l=linux-can&m=138377346111229&w=2

Then it's less probable that your latest patch will be realized.

Wolfgang.

Re: GS_USB

[Wolfgang Grandegger]

On 12/05/2013 09:18 PM, Wolfgang Grandegger wrote:
> Hi Max,
> 
> On 12/04/2013 10:17 PM, Max S. wrote:
>> Hey,
>>
>> Can someone give me a heads up on the GS_USB driver?
>>
>> Whats the next step? Is someone looking at it?
> 
> I will have a final look tomorrow or over the week-end. The driver was
> already in a good shape. Then it's up to Marc...
> 
> Anyway, next time please send the patch as standalone mail with the
> subject "[PATCH vX] can: gs_usb: ..." incrementing X for each new
> version. It's also common to briefly describe what has been changed
> below the "---" line. A rather good example is here:
> 
>   http://marc.info/?l=linux-can&m=138377346111229&w=2
> 
> Then it's less probable that your latest patch will be realized.

I mean "s/less/more/" or "s/will be/will not be/"

Wolfgang

Re: GS_USB

[Wolfgang Grandegger]

On 11/23/2013 05:05 PM, Max S. wrote:
> OK.
> 
> Here's the latest progress.
> 
> no line wrap this time :)
> 
>>From 74b99fe4e949a53d05ac35dc413e3ec3f9e352f6 Mon Sep 17 00:00:00 2001
> From: Maximilian Schneider <max@schneidersoft.net>
> Date: Sun, 3 Nov 2013 16:57:06 +0000
> Subject: [PATCH] Added support for the GS_USB CAN devices. The Geschwister
>  Schneider Family of devices are galvanically isolated
>  USB2.0 to CAN2.0A/B adapters. Currently two form factors
>  are available, a tethered dongle in a rugged enclosure, and
>  mini-pci-e card.

To avoid such long subjects, please read "man git commit":

"Though not required, it’s a good idea to begin the commit message with
 a single short (less than 50 character) line summarizing the change,
 followed by a blank line and then a more thorough description. Tools
 that turn commits into email, for example, use the first line on the
 Subject: line and the rest of the commit in the body."

> Signed-off-by: Maximilian Schneider <max@schneidersoft.net>
> ---
>  drivers/net/can/usb/Kconfig  |    8 +
>  drivers/net/can/usb/Makefile |    1 +
>  drivers/net/can/usb/gs_usb.c | 1005 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 1014 insertions(+)
>  create mode 100644 drivers/net/can/usb/gs_usb.c
> 
> diff --git a/drivers/net/can/usb/Kconfig b/drivers/net/can/usb/Kconfig
> index fc96a3d..f5e3e8c 100644
> --- a/drivers/net/can/usb/Kconfig
> +++ b/drivers/net/can/usb/Kconfig
> @@ -54,4 +54,12 @@ config CAN_8DEV_USB
>  	  This driver supports the USB2CAN interface
>  	  from 8 devices (http://www.8devices.com).
>  
> +config CAN_GS_USB
> +	tristate "Geschwister Schneider UG interfaces"
> +	---help---
> +	  This driver supports the Geschwister Schneider USB/CAN devices.
> +	  If unsure choose N,
> +	  choose Y for built in support,
> +	  M to compile as module (module will be named: gs_usb).
> +
>  endmenu
> diff --git a/drivers/net/can/usb/Makefile b/drivers/net/can/usb/Makefile
> index becef46..c21a521 100644
> --- a/drivers/net/can/usb/Makefile
> +++ b/drivers/net/can/usb/Makefile
> @@ -7,5 +7,6 @@ obj-$(CONFIG_CAN_ESD_USB2) += esd_usb2.o
>  obj-$(CONFIG_CAN_KVASER_USB) += kvaser_usb.o
>  obj-$(CONFIG_CAN_PEAK_USB) += peak_usb/
>  obj-$(CONFIG_CAN_8DEV_USB) += usb_8dev.o
> +obj-$(CONFIG_CAN_GS_USB) += gs_usb.o
>  
>  ccflags-$(CONFIG_CAN_DEBUG_DEVICES) := -DDEBUG
> diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
> new file mode 100644
> index 0000000..732f3cf
> --- /dev/null
> +++ b/drivers/net/can/usb/gs_usb.c
> @@ -0,0 +1,1005 @@
> +/* CAN driver for Geschwister Schneider USB/CAN devices.
> + *
> + * Copyright (C) 2013 Geschwister Schneider Technologie-,
> + * Entwicklungs- und Vertriebs UG (Haftungsbeschränkt).
> + *
> + * Many thanks to all socketcan devs!
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License as published
> + * by the Free Software Foundation; version 2 of the License.
> + *
> + * This program is distributed in the hope that it will be useful, but
> + * WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * General Public License for more details.
> + */
> +
> +#include <linux/init.h>
> +#include <linux/signal.h>
> +#include <linux/module.h>
> +#include <linux/netdevice.h>
> +#include <linux/usb.h>
> +
> +#include <linux/can.h>
> +#include <linux/can/dev.h>
> +#include <linux/can/error.h>
> +
> +/* Device specific constants */
> +#define USB_GSUSB_1_VENDOR_ID      0x1d50
> +#define USB_GSUSB_1_PRODUCT_ID     0x606f
> +
> +#define GSUSB_ENDPOINT_IN          1
> +#define GSUSB_ENDPOINT_OUT         2
> +
> +/* Device specific constants */
> +enum gs_usb_breq {
> +	GS_USB_BREQ_HOST_FORMAT = 0,
> +	GS_USB_BREQ_BITTIMING,
> +	GS_USB_BREQ_MODE,
> +	GS_USB_BREQ_BERR,
> +	GS_USB_BREQ_BT_CONST,
> +	GS_USB_BREQ_DEVICE_CONFIG
> +};
> +
> +enum gs_can_mode {
> +	/* reset a channel. turns it off */
> +	GS_CAN_MODE_RESET = 0,
> +	/* starts a channel */
> +	GS_CAN_MODE_START
> +};
> +
> +enum gs_can_state {
> +	GS_CAN_STATE_ERROR_ACTIVE = 0,
> +	GS_CAN_STATE_ERROR_WARNING,
> +	GS_CAN_STATE_ERROR_PASSIVE,
> +	GS_CAN_STATE_BUS_OFF,
> +	GS_CAN_STATE_STOPPED,
> +	GS_CAN_STATE_SLEEPING
> +};
> +
> +/* data types passed between host and device */
> +struct gs_host_config {
> +	u32 byte_order;
> +} __packed;
> +
> +struct gs_device_config {
> +	u8 reserved1;
> +	u8 reserved2;
> +	u8 reserved3;
> +	u8 icount;
> +	u32 sw_version;
> +	u32 hw_version;
> +} __packed;
> +
> +#define GS_CAN_MODE_NORMAL               0
> +#define GS_CAN_MODE_LISTEN_ONLY          (1<<0)
> +#define GS_CAN_MODE_LOOP_BACK            (1<<1)
> +#define GS_CAN_MODE_TRIPLE_SAMPLE        (1<<2)
> +#define GS_CAN_MODE_ONE_SHOT             (1<<3)
> +
> +struct gs_device_mode {
> +	u32 mode;
> +	u32 flags;
> +} __packed;
> +
> +struct gs_device_state {
> +	u32 state;
> +	u32 rxerr;
> +	u32 txerr;
> +} __packed;
> +
> +struct gs_device_bittiming {
> +	u32 prop_seg;
> +	u32 phase_seg1;
> +	u32 phase_seg2;
> +	u32 sjw;
> +	u32 brp;
> +} __packed;
> +
> +#define GS_CAN_FEATURE_LISTEN_ONLY      (1<<0)
> +#define GS_CAN_FEATURE_LOOP_BACK        (1<<1)
> +#define GS_CAN_FEATURE_TRIPLE_SAMPLE    (1<<2)
> +#define GS_CAN_FEATURE_ONE_SHOT         (1<<3)
> +
> +struct gs_device_bt_const {
> +	u32 feature;
> +	u32 fclk_can;
> +	u32 tseg1_min;
> +	u32 tseg1_max;
> +	u32 tseg2_min;
> +	u32 tseg2_max;
> +	u32 sjw_max;
> +	u32 brp_min;
> +	u32 brp_max;
> +	u32 brp_inc;
> +} __packed;
> +
> +#define GS_CAN_FLAG_OVERFLOW 1
> +
> +struct gs_host_frame {
> +	u32 echo_id;
> +	u32 can_id;
> +
> +	u8 can_dlc;
> +	u8 channel;
> +	u8 flags;
> +	u8 reserved;
> +
> +	u8 data[8];
> +} __packed;

Could you please add some comment on the *firmware* here or in the file
header, especially that it uses exactly the same flags and mask as for
CAN-Linux for can_id, flags, error flags etc. and therefore no mapping
is necessary. Otherwise it's magic how CAN frames are used and created.

> +
> +/* Only send a max of GS_MAX_TX_URBS frames per channel at a time. */
> +#define GS_MAX_TX_URBS 10
> +/* Only launch a max of GS_MAX_RX_URBS usb requests at a time. */
> +#define GS_MAX_RX_URBS 30
> +/* Maximum number of interfaces the driver supports per device.
> + * Current hardware only supports 2 interfaces. The future may vary.
> + */
> +#define GS_MAX_INTF 2
> +
> +struct gs_tx_context {
> +	struct gs_can *dev;
> +	unsigned int echo_id;
> +};
> +
> +struct gs_can {
> +	struct can_priv can; /* must be the first member */
> +
> +	struct gs_usb *parent;
> +
> +	struct net_device *netdev;
> +	struct usb_device *udev;
> +	struct usb_interface *iface;
> +
> +	struct can_bittiming_const bt_const;
> +	unsigned int channel;	/* channel number */
> +
> +	/* This lock prevents a race condition between xmit and recieve. */
> +	spinlock_t tx_ctx_lock;
> +	struct gs_tx_context tx_context[GS_MAX_TX_URBS];
> +
> +	struct usb_anchor tx_submitted;
> +	atomic_t active_tx_urbs;
> +};
> +
> +/* usb interface struct */
> +struct gs_usb {
> +	struct gs_can *canch[GS_MAX_INTF];
> +	struct usb_anchor rx_submitted;
> +	atomic_t active_channels;
> +	struct usb_device *udev;
> +};
> +
> +/* 'allocate' a tx context.
> + * returns a valid tx context or NULL if there is no space.
> + */
> +static struct gs_tx_context *gs_alloc_tx_context(struct gs_can *dev)
> +{
> +	int i = 0;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&dev->tx_ctx_lock, flags);
> +
> +	for (; i < GS_MAX_TX_URBS; i++) {
> +		if (dev->tx_context[i].echo_id == GS_MAX_TX_URBS) {
> +			dev->tx_context[i].echo_id = i;
> +			spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
> +			return &dev->tx_context[i];
> +		}
> +	}
> +
> +	spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
> +	return NULL;
> +}
> +
> +/* releases a tx context
> + */
> +static void gs_free_tx_context(struct gs_tx_context *txc)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&txc->dev->tx_ctx_lock, flags);
> +	txc->echo_id = GS_MAX_TX_URBS;
> +	spin_unlock_irqrestore(&txc->dev->tx_ctx_lock, flags);
> +}

You do not need a lock to assign a variable. It's done in one
instruction. I think I already commented on that.

> +/* Get a tx context by id.
> + */
> +static struct gs_tx_context *gs_get_tx_context(
> +	struct gs_can *dev,
> +	unsigned int id)

Still time for some nitpicking. Please start adding arguments on the
first line.

> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&dev->tx_ctx_lock, flags);
> +	if (id < GS_MAX_TX_URBS) {
> +		if (dev->tx_context[id].echo_id == id) {
> +			spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
> +			return &dev->tx_context[id];
> +		}
> +	}
> +	spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
> +	return NULL;
> +}
> +
> +/* Get a tx contexts id.
> + */
> +static unsigned int gs_tx_context_id(struct gs_tx_context *txc)
> +{
> +	unsigned int id;
> +	id = txc->echo_id;
> +	return id;
> +}

What is this helper function good for? Also it's shorter to just

	return txc->echo_id;

> +
> +static int gs_cmd_reset(struct gs_usb *gsusb, struct gs_can *gsdev)
> +{
> +	struct gs_device_mode *dm;
> +	struct usb_interface *intf = gsdev->iface;
> +	int rc;
> +
> +	dm = kzalloc(sizeof(*dm), GFP_KERNEL);
> +	if (!dm)
> +		return -ENOMEM;
> +
> +	dm->mode = GS_CAN_MODE_RESET;
> +
> +	rc = usb_control_msg(interface_to_usbdev(intf),
> +			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
> +			GS_USB_BREQ_MODE,
> +			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			gsdev->channel,
> +			0,
> +			dm,
> +			sizeof(*dm),
> +			1000);
> +
> +	return rc;
> +}
> +
> +static void gs_update_state(struct gs_can *dev, struct can_frame *cf)
> +{
> +	struct can_device_stats *can_stats = &dev->can.can_stats;
> +
> +	if (cf->can_id & CAN_ERR_RESTARTED) {
> +		dev->can.state = CAN_STATE_ERROR_ACTIVE;
> +		can_stats->restarts++;

Hm, is error active here correct ....

> +	} else if (cf->can_id & CAN_ERR_BUSOFF) {
> +		dev->can.state = CAN_STATE_BUS_OFF;
> +		can_stats->bus_off++;
> +	} else if (cf->can_id & CAN_ERR_CRTL) {
> +		if ((cf->data[1] & CAN_ERR_CRTL_TX_WARNING) ||
> +			(cf->data[1] & CAN_ERR_CRTL_RX_WARNING)) {
> +			dev->can.state = CAN_STATE_ERROR_WARNING;
> +			can_stats->error_warning++;
> +		} else if ((cf->data[1] & CAN_ERR_CRTL_TX_PASSIVE) ||
> +			(cf->data[1] & CAN_ERR_CRTL_RX_PASSIVE)) {
> +			dev->can.state = CAN_STATE_ERROR_PASSIVE;
> +			can_stats->error_passive++;
> +		} else {
> +			dev->can.state = CAN_STATE_ERROR_ACTIVE;

... or here. Normally the back to error active, when recovered from
bus-off, does come some time later. Anyway, please add for back to error
active:

    cf->can_id |= CAN_ERR_PROT;
    cf->data[2] = CAN_ERR_PROT_ACTIVE;

Or does the firmware already sets these bits. And did you re-check the
error messages when going error passive, bus-off, restarted, back to
error active. Do they look good now?

> +		}
> +	}
> +}
> +
> +static void gs_usb_recieve_bulk_callback(struct urb *urb)
> +{
> +	struct gs_usb *usbcan = urb->context;
> +	struct gs_can *dev;
> +	struct net_device *netdev;
> +	int rc;
> +	struct net_device_stats *stats;
> +	struct gs_host_frame *hf = urb->transfer_buffer;
> +	struct gs_tx_context *txc;
> +	struct can_frame *cf;
> +	struct sk_buff *skb;
> +
> +	BUG_ON(!usbcan);
> +
> +	switch (urb->status) {
> +	case 0: /* success */
> +		break;
> +	case -ENOENT:
> +	case -ESHUTDOWN:
> +		return;
> +	default:
> +		/* do not resubmit aborted urbs. eg: when device goes down */
> +		return;
> +	}
> +
> +	/* device reports out of range channel id */
> +	if (hf->channel >= GS_MAX_INTF)
> +		goto resubmit_urb;
> +
> +	/* device reports bad channel id */
> +	dev = usbcan->canch[hf->channel];
> +
> +	netdev = dev->netdev;
> +	stats = &netdev->stats;
> +
> +	if (!netif_device_present(netdev))
> +		return;
> +
> +	if (hf->echo_id == -1) { /* normal rx */
> +		skb = alloc_can_skb(dev->netdev, &cf);
> +		if (skb == NULL)
> +			return;

		if (!skb)

as you do for all other checks of that type.

> +
> +		cf->can_id = hf->can_id;
> +		/* is it necessary to use get_can_dlc? */
> +		cf->can_dlc = get_can_dlc(hf->can_dlc);
> +		memcpy(cf->data, hf->data, 8);
> +
> +		/* ERROR frames tell us information about the controller */
> +		if (hf->can_id & CAN_ERR_FLAG)
> +			gs_update_state(dev, cf);
> +
> +		netif_rx(skb);
> +
> +		netdev->stats.rx_packets++;
> +		netdev->stats.rx_bytes += hf->can_dlc;
> +	} else { /* echo_id == hf->echo_id */
> +		if (hf->echo_id >= GS_MAX_TX_URBS) {
> +			netdev_err(netdev,
> +				"Device sent an out of range echo id %d\n",
> +				hf->echo_id);
> +			goto resubmit_urb;
> +		}
> +
> +		netdev->stats.tx_packets++;
> +		netdev->stats.tx_bytes += hf->can_dlc;
> +
> +		txc = gs_get_tx_context(dev, hf->echo_id);
> +
> +		/* bad devices send bad echo_ids. */
> +		if (!txc) {
> +			netdev_err(netdev,
> +				"Device sent a bad echo id %d\n",
> +				hf->echo_id);
> +			goto resubmit_urb;
> +		}
> +
> +		can_get_echo_skb(netdev, gs_tx_context_id(txc));
> +
> +		gs_free_tx_context(txc);
> +
> +		netif_wake_queue(netdev);
> +	}
> +
> +	if (hf->flags & GS_CAN_FLAG_OVERFLOW) {
> +		skb = alloc_can_err_skb(netdev, &cf);
> +		if (skb == NULL)

Ditto.

> +			goto resubmit_urb;
> +
> +		cf->can_id |= CAN_ERR_CRTL;
> +		cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
> +		stats->rx_over_errors++;
> +		stats->rx_errors++;
> +		netif_rx(skb);
> +	}
> +
> +resubmit_urb:
> +	/* note: no urb refill... works for me */
> +	usb_fill_bulk_urb(urb,
> +			usbcan->udev,
> +			usb_rcvbulkpipe(usbcan->udev, GSUSB_ENDPOINT_IN),
> +			hf,
> +			sizeof(struct gs_host_frame),
> +			gs_usb_recieve_bulk_callback,
> +			usbcan
> +			);

Please move the ");" to the upper line as you do for the other function
calls as well.


> +
> +	rc = usb_submit_urb(urb, GFP_ATOMIC);
> +
> +	/* USB failure take down all interfaces */
> +	if (rc == -ENODEV) {
> +		for (rc = 0; rc < GS_MAX_INTF; rc++) {
> +			if (usbcan->canch[rc])
> +				netif_device_detach(usbcan->canch[rc]->netdev);
> +		}
> +	}
> +}
> +
> +static int gs_usb_set_bittiming(struct net_device *netdev)
> +{
> +	struct gs_can *dev = netdev_priv(netdev);
> +	struct can_bittiming *bt = &dev->can.bittiming;
> +	struct usb_interface *intf = dev->iface;
> +	int rc;
> +	struct gs_device_bittiming *dbt;
> +
> +	dbt = kmalloc(sizeof(*dbt), GFP_KERNEL);
> +	if (!dbt)
> +		return -ENOMEM;
> +
> +	dbt->prop_seg = bt->prop_seg;
> +	dbt->phase_seg1 = bt->phase_seg1;
> +	dbt->phase_seg2 = bt->phase_seg2;
> +	dbt->sjw = bt->sjw;
> +	dbt->brp = bt->brp;
> +
> +	rc = usb_control_msg(interface_to_usbdev(intf),
> +			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
> +			GS_USB_BREQ_BITTIMING,
> +			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			dev->channel,
> +			0,
> +			dbt,
> +			sizeof(*dbt),
> +			1000);
> +	if (rc < 0)
> +		dev_err(netdev->dev.parent, "Couldn't set bittimings %d", rc);
> +
> +	kfree(dbt);
> +
> +	return rc;
> +}
> +
> +static void gs_usb_xmit_callback(struct urb *urb)
> +{
> +	struct gs_tx_context *txc = urb->context;
> +	struct gs_can *dev = txc->dev;
> +	struct net_device *netdev = dev->netdev;
> +
> +	if (urb->status) {
> +		netdev_info(netdev, "%d] xmit err %d\n",
> +			dev->channel, txc->echo_id);
> +	}
> +
> +	usb_free_coherent(urb->dev,
> +		urb->transfer_buffer_length,
> +		urb->transfer_buffer,
> +		urb->transfer_dma);
> +
> +	atomic_dec(&dev->active_tx_urbs);
> +
> +	if (!netif_device_present(netdev))
> +		return;
> +
> +	if (netif_queue_stopped(netdev))
> +		netif_wake_queue(netdev);
> +}
> +
> +static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
> +	struct net_device *netdev)
> +{
> +	struct gs_can *dev = netdev_priv(netdev);
> +	struct net_device_stats *stats = &dev->netdev->stats;
> +	struct urb *urb;
> +	struct gs_host_frame *hf;
> +	struct can_frame *cf;
> +	int rc;
> +	unsigned int idx;
> +	struct gs_tx_context *txc;
> +
> +	if (dev->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
> +		return NETDEV_TX_BUSY;
> +
> +	if (can_dropped_invalid_skb(netdev, skb))
> +		return NETDEV_TX_OK;
> +
> +	/* find an empty context to keep track of transmission */
> +	txc = gs_alloc_tx_context(dev);
> +	if (!txc)
> +		return NETDEV_TX_BUSY;
> +
> +	/* create a URB, and a buffer for it */
> +	urb = usb_alloc_urb(0, GFP_ATOMIC);
> +	if (!urb) {
> +		netdev_err(netdev, "No memory left for URBs\n");
> +		goto nomem_urb;
> +	}
> +
> +	hf = usb_alloc_coherent(dev->udev, sizeof(*hf), GFP_ATOMIC,
> +		&urb->transfer_dma);
> +	if (!hf) {
> +		netdev_err(netdev, "No memory left for USB buffer\n");
> +		goto nomem_hf;
> +	}
> +
> +	idx = gs_tx_context_id(txc);
> +
> +	if (idx >= GS_MAX_TX_URBS) {
> +		netdev_err(netdev, "Invalid tx context %d\n", idx);
> +		goto badidx;
> +	}
> +
> +	hf->echo_id = idx;
> +	hf->channel = dev->channel;
> +
> +	cf = (struct can_frame *)skb->data;
> +
> +	hf->can_id = cf->can_id;
> +	hf->can_dlc = cf->can_dlc;
> +	memcpy(hf->data, cf->data, 8);

memcpy(hf->data, cf->data, cf->can_dlc); !

> +
> +	usb_fill_bulk_urb(urb, dev->udev,
> +			usb_sndbulkpipe(dev->udev, GSUSB_ENDPOINT_OUT),
> +			hf,
> +			sizeof(*hf),
> +			gs_usb_xmit_callback,
> +			txc);
> +
> +	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
> +	usb_anchor_urb(urb, &dev->tx_submitted);
> +
> +	can_put_echo_skb(skb, netdev, idx);
> +
> +	atomic_inc(&dev->active_tx_urbs);
> +
> +	rc = usb_submit_urb(urb, GFP_ATOMIC);
> +	if (unlikely(rc)) {			/* usb send failed */
> +		atomic_dec(&dev->active_tx_urbs);
> +
> +		netdev_err(netdev, "usb_submit failed %d\n", rc);
> +
> +		can_free_echo_skb(netdev, gs_tx_context_id(txc));
> +		gs_free_tx_context(txc);
> +
> +		usb_unanchor_urb(urb);
> +		usb_free_coherent(dev->udev,
> +			sizeof(*hf),
> +			hf,
> +			urb->transfer_dma);
> +
> +
> +		if (rc == -ENODEV) {
> +			netif_device_detach(netdev);
> +		} else {
> +			netdev_err(netdev, "Failed tx_urb %d\n", rc);
> +			stats->tx_dropped++;
> +		}
> +	} else {
> +		netdev->trans_start = jiffies;
> +
> +		/* Slow down tx path */
> +		if (atomic_read(&dev->active_tx_urbs) >= GS_MAX_TX_URBS)
> +			netif_stop_queue(netdev);
> +	}
> +
> +	/* let usb core take care of this urb */
> +	usb_free_urb(urb);
> +
> +	return NETDEV_TX_OK;
> +
> +badidx:
> +	usb_free_coherent(dev->udev,
> +				sizeof(*hf),
> +				hf,
> +				urb->transfer_dma);
> +nomem_hf:
> +	usb_free_urb(urb);
> +
> +nomem_urb:
> +	gs_free_tx_context(txc);
> +	dev_kfree_skb(skb);
> +	stats->tx_dropped++;
> +	return NETDEV_TX_OK;
> +}
> +
> +static int gs_can_open(struct net_device *netdev)
> +{
> +	struct gs_can *dev = netdev_priv(netdev);
> +	struct gs_usb *parent = dev->parent;
> +	int rc, i;
> +	struct gs_device_mode *dm;
> +	u32 ctrlmode;
> +
> +	rc = open_candev(netdev);
> +	if (rc)
> +		return rc;
> +
> +	if (atomic_add_return(1, &parent->active_channels) == 1) {
> +		for (i = 0; i < GS_MAX_RX_URBS; i++) {
> +			struct urb *urb = NULL;
> +			u8 *buf = NULL;
> +
> +			/* alloc rx urb */
> +			urb = usb_alloc_urb(0, GFP_KERNEL);
> +			if (!urb) {
> +				netdev_err(netdev,
> +					"No memory left for URBs\n");
> +				return -ENOMEM;
> +			}
> +
> +			/* alloc rx buffer */
> +			buf = usb_alloc_coherent(dev->udev,
> +				sizeof(struct gs_host_frame),
> +				GFP_KERNEL,
> +				&urb->transfer_dma);
> +			if (!buf) {
> +				netdev_err(netdev,
> +					"No memory left for USB buffer\n");
> +				usb_free_urb(urb);
> +				return -ENOMEM;
> +			}
> +
> +			/* fill, anchor, and submit rx urb */
> +			usb_fill_bulk_urb(urb,
> +					dev->udev,
> +					usb_rcvbulkpipe(dev->udev,
> +						GSUSB_ENDPOINT_IN),
> +					buf,
> +					sizeof(struct gs_host_frame),
> +					gs_usb_recieve_bulk_callback,
> +					parent
> +					);
> +			urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
> +
> +			usb_anchor_urb(urb, &parent->rx_submitted);
> +
> +			rc = usb_submit_urb(urb, GFP_KERNEL);
> +			if (rc) {
> +				if (rc == -ENODEV)
> +					netif_device_detach(dev->netdev);
> +
> +				usb_unanchor_urb(urb);
> +				break;
> +			}
> +
> +			/* Drop reference,
> +			 * USB core will take care of freeing it
> +			 */
> +			usb_free_urb(urb);
> +		}
> +	}
> +
> +	dm = kmalloc(sizeof(*dm), GFP_KERNEL);
> +	if (!dm)
> +		return -ENOMEM;
> +
> +	/* flags */
> +	ctrlmode = dev->can.ctrlmode;
> +	dm->flags = 0;
> +
> +	if (ctrlmode & CAN_CTRLMODE_LOOPBACK)
> +		dm->flags |= GS_CAN_MODE_LOOP_BACK;
> +	else if (ctrlmode & CAN_CTRLMODE_LISTENONLY)
> +		dm->flags |= GS_CAN_MODE_LISTEN_ONLY;
> +
> +	/* Controller is not allowed to retry TX
> +	 * this mode is unavailable on atmels uc3c hardware
> +	 */
> +	if (ctrlmode & CAN_CTRLMODE_ONE_SHOT)
> +		dm->flags |= GS_CAN_MODE_ONE_SHOT;
> +
> +	if (ctrlmode & CAN_CTRLMODE_3_SAMPLES)
> +		dm->flags |= GS_CAN_MODE_TRIPLE_SAMPLE;
> +
> +	/* finally start device */
> +	dm->mode = GS_CAN_MODE_START;
> +	rc = usb_control_msg(interface_to_usbdev(dev->iface),
> +			usb_sndctrlpipe(interface_to_usbdev(dev->iface), 0),
> +			GS_USB_BREQ_MODE,
> +			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			dev->channel,
> +			0,
> +			dm,
> +			sizeof(*dm),
> +			1000);
> +
> +	if (rc < 0) {
> +		netdev_err(netdev, "Couldn't start device (err=%d)\n", rc);
> +		kfree(dm);
> +		return rc;
> +	}
> +
> +	rc = usb_control_msg(interface_to_usbdev(dev->iface),
> +			usb_rcvctrlpipe(interface_to_usbdev(dev->iface), 0),
> +			GS_USB_BREQ_MODE,
> +			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			dev->channel,
> +			0,
> +			dm,
> +			sizeof(*dm),
> +			1000);
> +
> +	if (rc < 0) {
> +		netdev_err(netdev, "Couldn't get device mode (err=%d)\n",
> +			rc);
> +		kfree(dm);
> +		return rc;
> +	}
> +
> +	kfree(dm);
> +
> +	dev->can.state = CAN_STATE_ERROR_ACTIVE;
> +
> +	netif_start_queue(netdev);

	if (!(dev->can.ctrlmode & CAN_CTRLMODE_LISTENONLY))
		netif_start_queue(netdev);

That way, the xmit callback will never be called. I think we should add
these lines for all other drivers as well.

> +
> +	return 0;
> +}
> +
> +static int gs_can_close(struct net_device *netdev)
> +{
> +	int rc;
> +	struct gs_can *dev = netdev_priv(netdev);
> +	struct gs_usb *parent = dev->parent;
> +
> +	netif_stop_queue(netdev);
> +
> +	/* Stop polling */
> +	if (atomic_dec_and_test(&parent->active_channels))
> +		usb_kill_anchored_urbs(&parent->rx_submitted);
> +
> +	rc = gs_cmd_reset(parent, dev);
> +
> +	if (rc < 0)
> +		netdev_warn(netdev, "Couldn't shutdown device (err=%d)", rc);
> +
> +	close_candev(netdev);
> +
> +	return 0;
> +}
> +
> +/******************************** USB ********************************/
> +
> +static const struct net_device_ops gs_usb_netdev_ops = {
> +	.ndo_open = gs_can_open,
> +	.ndo_stop = gs_can_close,
> +	.ndo_start_xmit = gs_can_start_xmit,
> +};
> +
> +static struct gs_can *gs_make_candev(unsigned int channel,
> +	struct usb_interface *intf)
> +{
> +	struct gs_can *dev;
> +	struct net_device *netdev;
> +	int rc;
> +	struct gs_device_bt_const *bt_const;
> +
> +	bt_const = kmalloc(sizeof(*bt_const), GFP_KERNEL);
> +	if (!bt_const)
> +		return ERR_PTR(-ENOMEM);

This function does not return an error code, therefore just:

		return -ENOMEM;

> +
> +	/* fetch bit timing constants */
> +	rc = usb_control_msg(interface_to_usbdev(intf),
> +			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
> +			GS_USB_BREQ_BT_CONST,
> +			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			channel,
> +			0,
> +			bt_const,
> +			sizeof(*bt_const),
> +			1000);
> +
> +	if (rc < 0) {
> +		dev_err(&intf->dev,
> +			"Couldn't get bit timing const for channel (err=%d)\n",
> +			rc);
> +		kfree(bt_const);
> +		return ERR_PTR(rc);

		return rc; !

Puh, at a closer look there are quite some issues with returning a
proper return code.

> +	}
> +
> +	/* create netdev */
> +	netdev = alloc_candev(sizeof(struct gs_can), GS_MAX_TX_URBS);
> +	if (!netdev) {
> +		dev_err(&intf->dev, "Couldn't alloc candev\n");
> +		kfree(bt_const);
> +		return ERR_PTR(-ENOMEM);

This function does not return an error code, therefore just:

		return -ENOMEM;

> +	}
> +
> +	dev = netdev_priv(netdev);
> +
> +	netdev->netdev_ops = &gs_usb_netdev_ops;
> +
> +	netdev->flags |= IFF_ECHO; /* we support full roundtrip echo */
> +
> +	/* dev settup */
> +	strcpy(dev->bt_const.name, "gs_usb");
> +	dev->bt_const.tseg1_min = bt_const->tseg1_min;
> +	dev->bt_const.tseg1_max = bt_const->tseg1_max;
> +	dev->bt_const.tseg2_min = bt_const->tseg2_min;
> +	dev->bt_const.tseg2_max = bt_const->tseg2_max;
> +	dev->bt_const.sjw_max = bt_const->sjw_max;
> +	dev->bt_const.brp_min = bt_const->brp_min;
> +	dev->bt_const.brp_max = bt_const->brp_max;
> +	dev->bt_const.brp_inc = bt_const->brp_inc;
> +
> +	dev->udev = interface_to_usbdev(intf);
> +	dev->iface = intf;
> +	dev->netdev = netdev;
> +	dev->channel = channel;
> +
> +	init_usb_anchor(&dev->tx_submitted);
> +	atomic_set(&dev->active_tx_urbs, 0);
> +	spin_lock_init(&dev->tx_ctx_lock);
> +	for (rc = 0; rc < GS_MAX_TX_URBS; rc++) {
> +		dev->tx_context[rc].dev = dev;
> +		dev->tx_context[rc].echo_id = GS_MAX_TX_URBS;
> +	}
> +
> +	/* can settup */
> +	dev->can.state = CAN_STATE_STOPPED;
> +	dev->can.clock.freq = bt_const->fclk_can;
> +	dev->can.bittiming_const = &dev->bt_const;
> +	dev->can.do_set_bittiming = gs_usb_set_bittiming;
> +
> +	dev->can.ctrlmode_supported = 0;
> +
> +	if (bt_const->feature & GS_CAN_FEATURE_LISTEN_ONLY)
> +		dev->can.ctrlmode_supported |= CAN_CTRLMODE_LISTENONLY;
> +
> +	if (bt_const->feature & GS_CAN_FEATURE_LOOP_BACK)
> +		dev->can.ctrlmode_supported |= CAN_CTRLMODE_LOOPBACK;
> +
> +	if (bt_const->feature & GS_CAN_FEATURE_TRIPLE_SAMPLE)
> +		dev->can.ctrlmode_supported |= CAN_CTRLMODE_3_SAMPLES;
> +
> +	if (bt_const->feature & GS_CAN_FEATURE_ONE_SHOT)
> +		dev->can.ctrlmode_supported |= CAN_CTRLMODE_ONE_SHOT;
> +
> +	kfree(bt_const);
> +
> +	SET_NETDEV_DEV(netdev, &intf->dev);
> +
> +	rc = register_candev(dev->netdev);
> +	if (rc) {
> +		free_candev(dev->netdev);
> +		dev_err(&intf->dev, "Couldn't register candev\n");
> +		return ERR_PTR(rc);

		return rc; !!!

> +	}
> +
> +	return dev;
> +}
> +
> +static void gs_destroy_candev(struct gs_can *dev)
> +{
> +	unregister_candev(dev->netdev);
> +	free_candev(dev->netdev);
> +	usb_kill_anchored_urbs(&dev->tx_submitted);
> +}
> +
> +static int gs_usb_probe(struct usb_interface *intf,
> +	const struct usb_device_id *id)
> +{
> +	struct gs_usb *dev;
> +	int rc = -ENOMEM;
> +	unsigned int icount, i;
> +	struct gs_host_config *hconf;
> +	struct gs_device_config *dconf;
> +
> +	hconf = kmalloc(sizeof(*hconf), GFP_KERNEL);
> +	if (!hconf)
> +		return -ENOMEM;
> +
> +	hconf->byte_order = 0x0000beef;
> +
> +	/* send host config */
> +	rc = usb_control_msg(interface_to_usbdev(intf),
> +			usb_sndctrlpipe(interface_to_usbdev(intf), 0),
> +			GS_USB_BREQ_HOST_FORMAT,
> +			USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			1,
> +			intf->altsetting[0].desc.bInterfaceNumber,
> +			hconf,
> +			sizeof(*hconf),
> +			1000);
> +
> +	kfree(hconf);
> +
> +	if (rc < 0) {
> +		dev_err(&intf->dev, "Couldn't send data format: %d\n",
> +			rc);
> +		return rc;
> +	}
> +
> +
> +	dconf = kmalloc(sizeof(*dconf), GFP_KERNEL);
> +	if (!dconf)
> +		return -ENOMEM;
> +
> +	/* read device config */
> +	rc = usb_control_msg(interface_to_usbdev(intf),
> +			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
> +			GS_USB_BREQ_DEVICE_CONFIG,
> +			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
> +			1,
> +			intf->altsetting[0].desc.bInterfaceNumber,
> +			dconf,
> +			sizeof(*dconf),
> +			1000);
> +	if (rc < 0) {
> +		dev_err(&intf->dev, "Couldn't recieve device config: %d\n",
> +			rc);
> +
> +		kfree(dconf);
> +
> +		return rc;
> +	}
> +
> +	icount = dconf->icount+1;

s/+/ + /

> +
> +	kfree(dconf);
> +
> +	dev_info(&intf->dev, "Configuring for %d interfaces\n", icount);
> +
> +	if (icount > GS_MAX_INTF) {
> +		dev_err(&intf->dev,
> +			"Driver cannot handle more that %d CAN interfaces\n",
> +			GS_MAX_INTF);
> +		return -EINVAL;
> +	}
> +
> +	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
> +	init_usb_anchor(&dev->rx_submitted);
> +
> +	atomic_set(&dev->active_channels, 0);
> +
> +	usb_set_intfdata(intf, dev);
> +	dev->udev = interface_to_usbdev(intf);
> +
> +	for (i = 0; i < icount; i++) {
> +		dev->canch[i] = gs_make_candev(i, intf);
> +		if (IS_ERR_OR_NULL(dev->canch[i])) {
> +			/* on failure destroy previously created candevs */
> +			icount = i;
> +			for (i = 0; i < icount; i++) {
> +				gs_destroy_candev(dev->canch[i]);
> +				dev->canch[icount] = NULL;
> +			}
> +			return rc;
> +		}
> +		dev->canch[i]->parent = dev;
> +	}
> +
> +	dev_info(&intf->dev, "Probe\n");

Please remove. You may want to add an info line at the end of
gs_make_candev() to report firmware version or other information useful
for the *normal* user.

> +	return 0;
> +}
> +
> +static void gs_usb_disconnect(struct usb_interface *intf)
> +{
> +	unsigned i;
> +	struct gs_usb *dev = usb_get_intfdata(intf);
> +	usb_set_intfdata(intf, NULL);
> +
> +	if (!dev) {
> +		dev_err(&intf->dev, "Disconnect (nodata)\n");
> +		return;
> +	}
> +
> +	for (i = 0; i < GS_MAX_INTF; i++) {
> +		struct gs_can *can = dev->canch[i];
> +
> +		if (!can)
> +			continue;
> +
> +		gs_destroy_candev(can);
> +	}
> +
> +	usb_kill_anchored_urbs(&dev->rx_submitted);
> +}
> +
> +MODULE_DEVICE_TABLE(usb, gs_usb_table);
> +
> +static struct usb_device_id gs_usb_table[] = {
> +	{USB_DEVICE(USB_GSUSB_1_VENDOR_ID, USB_GSUSB_1_PRODUCT_ID)},
> +	{} /* Terminating entry */
> +};
> +
> +static struct usb_driver gs_usb_driver = {
> +	.name       = "gs_usb",
> +	.probe      = gs_usb_probe,
> +	.disconnect = gs_usb_disconnect,
> +	.id_table   = gs_usb_table

Please add a "," here as well.

> +};
> +
> +static int __init gs_usb_init(void)
> +{
> +	return usb_register(&gs_usb_driver);
> +}
> +
> +static void __exit gs_usb_exit(void)
> +{
> +	usb_deregister(&gs_usb_driver);
> +}
> +
> +module_init(gs_usb_init);
> +module_exit(gs_usb_exit);
> +
> +MODULE_AUTHOR("Maximilian Schneider <mws@schneidersoft.net>");
> +MODULE_DESCRIPTION(
> +"Socket CAN device driver for Geschwister Schneider Technologie-, "
> +"Entwicklungs- und Vertriebs UG. USB2.0 to CAN interfaces.");
> +MODULE_LICENSE("GPL v2");
> +

Wolfgang.

Re: GS_USB

[Marc Kleine-Budde]

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Hello Wolfgang,

thanks for reviewing the driver.

On 12/07/2013 11:06 AM, Wolfgang Grandegger wrote:
>> +static struct gs_can *gs_make_candev(unsigned int channel,
>> > +	struct usb_interface *intf)

This function returns a struct gs_can pointer...

>> > +{
>> > +	struct gs_can *dev;
>> > +	struct net_device *netdev;
>> > +	int rc;
>> > +	struct gs_device_bt_const *bt_const;
>> > +
>> > +	bt_const = kmalloc(sizeof(*bt_const), GFP_KERNEL);
>> > +	if (!bt_const)
>> > +		return ERR_PTR(-ENOMEM);
> This function does not return an error code, therefore just:
> 
> 		return -ENOMEM;

....so ERR_PTR(-ENOMEM) is correct. The error value "-ENOMEM" has to be
converted to a pointer and this is what ERR_PTR does. The same is true
for the rest of this function.

> 
>> > +
>> > +	/* fetch bit timing constants */
>> > +	rc = usb_control_msg(interface_to_usbdev(intf),
>> > +			usb_rcvctrlpipe(interface_to_usbdev(intf), 0),
>> > +			GS_USB_BREQ_BT_CONST,
>> > +			USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
>> > +			channel,
>> > +			0,
>> > +			bt_const,
>> > +			sizeof(*bt_const),
>> > +			1000);
>> > +
>> > +	if (rc < 0) {
>> > +		dev_err(&intf->dev,
>> > +			"Couldn't get bit timing const for channel (err=%d)\n",
>> > +			rc);
>> > +		kfree(bt_const);
>> > +		return ERR_PTR(rc);
> 		return rc; !
> 
> Puh, at a closer look there are quite some issues with returning a
> proper return code.
> 
>> > +	}
>> > +
>> > +	/* create netdev */
>> > +	netdev = alloc_candev(sizeof(struct gs_can), GS_MAX_TX_URBS);
>> > +	if (!netdev) {
>> > +		dev_err(&intf->dev, "Couldn't alloc candev\n");
>> > +		kfree(bt_const);
>> > +		return ERR_PTR(-ENOMEM);
> This function does not return an error code, therefore just:
> 
> 		return -ENOMEM;
> 
>> > +	}
>> > +
>> > +	dev = netdev_priv(netdev);
>> > +
>> > +	netdev->netdev_ops = &gs_usb_netdev_ops;
>> > +
>> > +	netdev->flags |= IFF_ECHO; /* we support full roundtrip echo */
>> > +
>> > +	/* dev settup */
>> > +	strcpy(dev->bt_const.name, "gs_usb");
>> > +	dev->bt_const.tseg1_min = bt_const->tseg1_min;
>> > +	dev->bt_const.tseg1_max = bt_const->tseg1_max;
>> > +	dev->bt_const.tseg2_min = bt_const->tseg2_min;
>> > +	dev->bt_const.tseg2_max = bt_const->tseg2_max;
>> > +	dev->bt_const.sjw_max = bt_const->sjw_max;
>> > +	dev->bt_const.brp_min = bt_const->brp_min;
>> > +	dev->bt_const.brp_max = bt_const->brp_max;
>> > +	dev->bt_const.brp_inc = bt_const->brp_inc;
>> > +
>> > +	dev->udev = interface_to_usbdev(intf);
>> > +	dev->iface = intf;
>> > +	dev->netdev = netdev;
>> > +	dev->channel = channel;
>> > +
>> > +	init_usb_anchor(&dev->tx_submitted);
>> > +	atomic_set(&dev->active_tx_urbs, 0);
>> > +	spin_lock_init(&dev->tx_ctx_lock);
>> > +	for (rc = 0; rc < GS_MAX_TX_URBS; rc++) {
>> > +		dev->tx_context[rc].dev = dev;
>> > +		dev->tx_context[rc].echo_id = GS_MAX_TX_URBS;
>> > +	}
>> > +
>> > +	/* can settup */
>> > +	dev->can.state = CAN_STATE_STOPPED;
>> > +	dev->can.clock.freq = bt_const->fclk_can;
>> > +	dev->can.bittiming_const = &dev->bt_const;
>> > +	dev->can.do_set_bittiming = gs_usb_set_bittiming;
>> > +
>> > +	dev->can.ctrlmode_supported = 0;
>> > +
>> > +	if (bt_const->feature & GS_CAN_FEATURE_LISTEN_ONLY)
>> > +		dev->can.ctrlmode_supported |= CAN_CTRLMODE_LISTENONLY;
>> > +
>> > +	if (bt_const->feature & GS_CAN_FEATURE_LOOP_BACK)
>> > +		dev->can.ctrlmode_supported |= CAN_CTRLMODE_LOOPBACK;
>> > +
>> > +	if (bt_const->feature & GS_CAN_FEATURE_TRIPLE_SAMPLE)
>> > +		dev->can.ctrlmode_supported |= CAN_CTRLMODE_3_SAMPLES;
>> > +
>> > +	if (bt_const->feature & GS_CAN_FEATURE_ONE_SHOT)
>> > +		dev->can.ctrlmode_supported |= CAN_CTRLMODE_ONE_SHOT;
>> > +
>> > +	kfree(bt_const);
>> > +
>> > +	SET_NETDEV_DEV(netdev, &intf->dev);
>> > +
>> > +	rc = register_candev(dev->netdev);
>> > +	if (rc) {
>> > +		free_candev(dev->netdev);
>> > +		dev_err(&intf->dev, "Couldn't register candev\n");
>> > +		return ERR_PTR(rc);
> 		return rc; !!!
> 
>> > +	}
>> > +
>> > +	return dev;
>> > +}

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |


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Re: GS_USB

[Wolfgang Grandegger]

On 12/09/2013 11:52 AM, Marc Kleine-Budde wrote:
> Hello Wolfgang,
> 
> thanks for reviewing the driver.
> 
> On 12/07/2013 11:06 AM, Wolfgang Grandegger wrote:
>>> +static struct gs_can *gs_make_candev(unsigned int channel,
>>>> +	struct usb_interface *intf)
> 
> This function returns a struct gs_can pointer...
> 
>>>> +{
>>>> +	struct gs_can *dev;
>>>> +	struct net_device *netdev;
>>>> +	int rc;
>>>> +	struct gs_device_bt_const *bt_const;
>>>> +
>>>> +	bt_const = kmalloc(sizeof(*bt_const), GFP_KERNEL);
>>>> +	if (!bt_const)
>>>> +		return ERR_PTR(-ENOMEM);
>> This function does not return an error code, therefore just:
>>
>> 		return -ENOMEM;
> 
> ....so ERR_PTR(-ENOMEM) is correct. The error value "-ENOMEM" has to be
> converted to a pointer and this is what ERR_PTR does. The same is true
> for the rest of this function.

Of course. Obviously I got confused as well.

Wolfgang.