[PATCH v5 0/4] mfd: add support for Diolan DLN-2

[PATCH v5 0/4] mfd: add support for Diolan DLN-2

[Octavian Purdila]

This patch series adds support for Diolan USB-I2C/GPIO Master Adapter
DLN-2. Details about device can be found here:

https://www.diolan.com/i2c/i2c_interface.html.

Changes since v4:

* Add a new gpiolib chip flag to allow blocking chips with non threaded
  IRQ handlers

* MFD: set GPLv2 as license, fix a couple of coding style issues, add
  code to stop I/O after USB disconnect and prevent further I/O,
  simplify the DNL2 platform data

* GPIO: add modalias, set GPLv2 as license, rework pin direction
  caching, use irq_find_mapping in dln2_irq_unmask, allocate irq work
  based on the number of pins read from the device, flush irq work at
  remove time, use RCU to iterate and run the callback list

* I2C: add modalias, set GPLv2 as license, allocate the RX/TX buf
  separately to avoid cache line sharing issue, don't truncate i2c
  reads, use u32 instead of uint32_t, attach the sysfs freq attribute
  to the i2c adapter device instead of the platform device (and also
  use device attribute groups), simplify dln2_i2c_read a bit


Daniel Baluta (1):
  gpio: add support for the Diolan DLN-2 USB GPIO driver

Laurentiu Palcu (1):
  i2c: add support for Diolan DLN-2 USB-I2C adapter

Octavian Purdila (2):
  mfd: add support for Diolan DLN-2 devices
  gpiolib: add irq_not_threaded flag to gpio_chip

 drivers/gpio/Kconfig          |  12 +
 drivers/gpio/Makefile         |   1 +
 drivers/gpio/gpio-dln2.c      | 554 ++++++++++++++++++++++++++++++
 drivers/gpio/gpiolib.c        |   2 +-
 drivers/i2c/busses/Kconfig    |  10 +
 drivers/i2c/busses/Makefile   |   1 +
 drivers/i2c/busses/i2c-dln2.c | 383 +++++++++++++++++++++
 drivers/mfd/Kconfig           |   9 +
 drivers/mfd/Makefile          |   1 +
 drivers/mfd/dln2.c            | 758 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/gpio/driver.h   |   3 +
 include/linux/mfd/dln2.h      |  67 ++++
 12 files changed, 1800 insertions(+), 1 deletion(-)
 create mode 100644 drivers/gpio/gpio-dln2.c
 create mode 100644 drivers/i2c/busses/i2c-dln2.c
 create mode 100644 drivers/mfd/dln2.c
 create mode 100644 include/linux/mfd/dln2.h

-- 
1.9.1

[PATCH v5 1/4] mfd: add support for Diolan DLN-2 devices

[Octavian Purdila]

This patch implements the USB part of the Diolan USB-I2C/SPI/GPIO
Master Adapter DLN-2. Details about the device can be found here:

https://www.diolan.com/i2c/i2c_interface.html.

Information about the USB protocol can be found in the Programmer's
Reference Manual [1], see section 1.7.

Because the hardware has a single transmit endpoint and a single
receive endpoint the communication between the various DLN2 drivers
and the hardware will be muxed/demuxed by this driver.

Each DLN2 module will be identified by the handle field within the DLN2
message header. If a DLN2 module issues multiple commands in parallel
they will be identified by the echo counter field in the message header.

The DLN2 modules can use the dln2_transfer() function to issue a
command and wait for its response. They can also register a callback
that is going to be called when a specific event id is generated by
the device (e.g. GPIO interrupts). The device uses handle 0 for
sending events.

[1] https://www.diolan.com/downloads/dln-api-manual.pdf

Signed-off-by: Octavian Purdila <octavian.purdila-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 drivers/mfd/Kconfig      |   9 +
 drivers/mfd/Makefile     |   1 +
 drivers/mfd/dln2.c       | 758 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/mfd/dln2.h |  67 +++++
 4 files changed, 835 insertions(+)
 create mode 100644 drivers/mfd/dln2.c
 create mode 100644 include/linux/mfd/dln2.h

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index de5abf2..7bcf895 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -183,6 +183,15 @@ config MFD_DA9063
 	  Additional drivers must be enabled in order to use the functionality
 	  of the device.
 
+config MFD_DLN2
+	tristate "Diolan DLN2 support"
+	select MFD_CORE
+	depends on USB
+	help
+	  This adds support for Diolan USB-I2C/SPI/GPIO Master Adapter DLN-2.
+	  Additional drivers must be enabled in order to use the functionality
+	  of the device.
+
 config MFD_MC13XXX
 	tristate
 	depends on (SPI_MASTER || I2C)
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index f001487..591988d 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -169,6 +169,7 @@ obj-$(CONFIG_MFD_AS3711)	+= as3711.o
 obj-$(CONFIG_MFD_AS3722)	+= as3722.o
 obj-$(CONFIG_MFD_STW481X)	+= stw481x.o
 obj-$(CONFIG_MFD_IPAQ_MICRO)	+= ipaq-micro.o
+obj-$(CONFIG_MFD_DLN2)		+= dln2.o
 
 intel-soc-pmic-objs		:= intel_soc_pmic_core.o intel_soc_pmic_crc.o
 obj-$(CONFIG_INTEL_SOC_PMIC)	+= intel-soc-pmic.o
diff --git a/drivers/mfd/dln2.c b/drivers/mfd/dln2.c
new file mode 100644
index 0000000..36c53cd
--- /dev/null
+++ b/drivers/mfd/dln2.c
@@ -0,0 +1,758 @@
+/*
+ * Driver for the Diolan DLN-2 USB adapter
+ *
+ * Copyright (c) 2014 Intel Corporation
+ *
+ * Derived from:
+ *  i2c-diolan-u2c.c
+ *  Copyright (c) 2010-2011 Ericsson AB
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+#include <linux/i2c.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/dln2.h>
+#include <linux/rculist.h>
+
+struct dln2_header {
+	__le16 size;
+	__le16 id;
+	__le16 echo;
+	__le16 handle;
+} __packed;
+
+struct dln2_response {
+	struct dln2_header hdr;
+	__le16 result;
+} __packed;
+
+#define DLN2_GENERIC_MODULE_ID		0x00
+#define DLN2_GENERIC_CMD(cmd)		DLN2_CMD(cmd, DLN2_GENERIC_MODULE_ID)
+#define CMD_GET_DEVICE_VER		DLN2_GENERIC_CMD(0x30)
+#define CMD_GET_DEVICE_SN		DLN2_GENERIC_CMD(0x31)
+
+#define DLN2_HW_ID			0x200
+#define DLN2_USB_TIMEOUT		200	/* in ms */
+#define DLN2_MAX_RX_SLOTS		16
+#define DLN2_MAX_URBS			16
+#define DLN2_RX_BUF_SIZE		512
+
+#define DLN2_HANDLE_EVENT		0
+#define DLN2_HANDLE_CTRL		1
+#define DLN2_HANDLE_GPIO		2
+#define DLN2_HANDLE_I2C			3
+#define DLN2_HANDLES			4
+
+
+/*
+ * Receive context used between the receive demultiplexer and the
+ * transfer routine. While sending a request the transfer routine
+ * will look for a free receive context and use it to wait for a
+ * response and to receive the URB and thus the response data.
+ */
+struct dln2_rx_context {
+	/* completion used to wait a response */
+	struct completion done;
+
+	/* if non-NULL the URB contains the response */
+	struct urb *urb;
+
+	/* if true then this context is used to wait for a response */
+	bool connected;
+
+	/* cancel waiting for a response, e.g. on USB disconnect */
+	bool cancel;
+};
+
+/*
+ * Receive contexts for a particular DLN2 module (i2c, gpio, etc.). We
+ * use the handle header field to indentify the module in
+ * dln2_dev.mod_rx_slots and then the echo header field to index the
+ * slots field and find the receive context for a particular
+ * request.
+ */
+struct dln2_mod_rx_slots {
+	/* RX slots bitmap */
+	unsigned long bmap;
+
+	/* used to wait for a free RX slot */
+	wait_queue_head_t wq;
+
+	/* used to wait for an RX operation to complete */
+	struct dln2_rx_context slots[DLN2_MAX_RX_SLOTS];
+
+	/* device has been disconnected */
+	bool disconnected;
+
+	/* avoid races between free_rx_slot, dln2_rx_transfer and dln2_stop */
+	spinlock_t lock;
+};
+
+struct dln2_dev {
+	struct usb_device *usb_dev;
+	struct usb_interface *interface;
+	u8 ep_in;
+	u8 ep_out;
+
+	struct urb *rx_urb[DLN2_MAX_URBS];
+	void *rx_buf[DLN2_MAX_URBS];
+
+	struct dln2_mod_rx_slots mod_rx_slots[DLN2_HANDLES];
+
+	struct list_head rx_cb_list;
+	spinlock_t rx_cb_lock;
+};
+
+static bool find_free_slot(struct dln2_mod_rx_slots *rxs, int *slot)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&rxs->lock, flags);
+
+	if (rxs->disconnected) {
+		*slot = -ECONNRESET;
+		goto out;
+	}
+
+	*slot = find_first_zero_bit(&rxs->bmap, DLN2_MAX_RX_SLOTS);
+
+	if (*slot < DLN2_MAX_RX_SLOTS) {
+		struct dln2_rx_context *rxc = &rxs->slots[*slot];
+
+		set_bit(*slot, &rxs->bmap);
+		rxc->connected = true;
+	}
+
+out:
+	spin_unlock_irqrestore(&rxs->lock, flags);
+
+	return *slot < DLN2_MAX_RX_SLOTS;
+}
+
+static int alloc_rx_slot(struct dln2_mod_rx_slots *rxs)
+{
+	int ret;
+	int slot;
+
+	/*
+	 * No need to timeout here, the wait is bounded by the timeout
+	 * in _dln2_transfer.
+	 */
+	ret = wait_event_interruptible(rxs->wq, find_free_slot(rxs, &slot));
+	if (ret < 0)
+		return ret;
+
+	return slot;
+}
+
+static void free_rx_slot(struct dln2_dev *dln2, struct dln2_mod_rx_slots *rxs,
+			 int slot)
+{
+	struct urb *urb = NULL;
+	unsigned long flags;
+	struct dln2_rx_context *rxc;
+	struct device *dev = &dln2->interface->dev;
+	int ret;
+
+	spin_lock_irqsave(&rxs->lock, flags);
+
+	clear_bit(slot, &rxs->bmap);
+
+	rxc = &rxs->slots[slot];
+	rxc->connected = false;
+	urb = rxc->urb;
+	rxc->urb = NULL;
+	reinit_completion(&rxc->done);
+
+	spin_unlock_irqrestore(&rxs->lock, flags);
+
+	if (urb) {
+		ret = usb_submit_urb(urb, GFP_KERNEL);
+		if (ret < 0)
+			dev_err(dev, "failed to re-submit RX URB: %d\n", ret);
+	}
+
+	wake_up_interruptible(&rxs->wq);
+}
+
+struct dln2_rx_cb_entry {
+	struct list_head list;
+	u16 id;
+	struct platform_device *pdev;
+	dln2_rx_cb_t callback;
+};
+
+int dln2_register_event_cb(struct platform_device *pdev, u16 id,
+			   dln2_rx_cb_t rx_cb)
+{
+	struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
+	struct dln2_rx_cb_entry *i, *new;
+	unsigned long flags;
+	int ret = 0;
+
+	new = kmalloc(sizeof(*new), GFP_KERNEL);
+	if (!new)
+		return -ENOMEM;
+
+	new->id = id;
+	new->callback = rx_cb;
+	new->pdev = pdev;
+
+	spin_lock_irqsave(&dln2->rx_cb_lock, flags);
+
+	list_for_each_entry_rcu(i, &dln2->rx_cb_list, list) {
+		if (i->id == id) {
+			ret = -EBUSY;
+			break;
+		}
+	}
+
+	if (!ret)
+		list_add_rcu(&new->list, &dln2->rx_cb_list);
+
+	spin_unlock_irqrestore(&dln2->rx_cb_lock, flags);
+
+	if (ret)
+		kfree(new);
+
+	return ret;
+}
+EXPORT_SYMBOL(dln2_register_event_cb);
+
+void dln2_unregister_event_cb(struct platform_device *pdev, u16 id)
+{
+	struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
+	struct dln2_rx_cb_entry *i;
+	unsigned long flags;
+	bool found = false;
+
+	spin_lock_irqsave(&dln2->rx_cb_lock, flags);
+
+	list_for_each_entry_rcu(i, &dln2->rx_cb_list, list) {
+		if (i->id == id) {
+			list_del_rcu(&i->list);
+			found = true;
+			break;
+		}
+	}
+
+	spin_unlock_irqrestore(&dln2->rx_cb_lock, flags);
+
+	if (found) {
+		synchronize_rcu();
+		kfree(i);
+	}
+}
+EXPORT_SYMBOL(dln2_unregister_event_cb);
+
+static void dln2_rx_transfer(struct dln2_dev *dln2, struct urb *urb,
+			     u16 handle, u16 rx_slot)
+{
+	struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
+	struct dln2_rx_context *rxc;
+	struct device *dev = &dln2->interface->dev;
+	int err;
+
+	spin_lock(&rxs->lock);
+	rxc = &rxs->slots[rx_slot];
+	if (rxc->connected) {
+		rxc->urb = urb;
+		complete(&rxc->done);
+	} else {
+		dev_warn(dev, "dropping response %d/%d", handle, rx_slot);
+		err = usb_submit_urb(urb, GFP_ATOMIC);
+		if (err < 0)
+			dev_err(dev, "failed to re-submit RX URB: %d\n", err);
+	}
+	spin_unlock(&rxs->lock);
+}
+
+static void dln2_run_rx_callbacks(struct dln2_dev *dln2, u16 id, u16 echo,
+				  void *data, int len)
+{
+	struct dln2_rx_cb_entry *i;
+
+	rcu_read_lock();
+
+	list_for_each_entry_rcu(i, &dln2->rx_cb_list, list)
+		if (i->id == id)
+			i->callback(i->pdev, echo, data, len);
+
+	rcu_read_unlock();
+}
+
+static void dln2_rx(struct urb *urb)
+{
+	int err;
+	struct dln2_dev *dln2 = urb->context;
+	struct dln2_header *hdr = urb->transfer_buffer;
+	struct device *dev = &dln2->interface->dev;
+	u16 id, echo, handle, size;
+	u8 *data;
+	int len;
+
+	switch (urb->status) {
+	case 0:
+		/* success */
+		break;
+	case -ECONNRESET:
+	case -ENOENT:
+	case -ESHUTDOWN:
+	case -EPIPE:
+		/* this urb is terminated, clean up */
+		dev_dbg(dev, "urb shutting down with status %d\n", urb->status);
+		return;
+	default:
+		dev_dbg(dev, "nonzero urb status received %d\n", urb->status);
+		goto out;
+	}
+
+	if (urb->actual_length < sizeof(struct dln2_header)) {
+		dev_err(dev, "short response: %d\n", urb->actual_length);
+		goto out;
+	}
+
+	handle = le16_to_cpu(hdr->handle);
+	id = le16_to_cpu(hdr->id);
+	echo = le16_to_cpu(hdr->echo);
+	size = le16_to_cpu(hdr->size);
+
+	if (size != urb->actual_length) {
+		dev_err(dev, "size mismatch: handle %x cmd %x echo %x size %d actual %d\n",
+			handle, id, echo, size, urb->actual_length);
+		goto out;
+	}
+
+	if (handle >= DLN2_HANDLES) {
+		dev_warn(dev, "RX: invalid handle %d\n", handle);
+		goto out;
+	}
+
+	data = urb->transfer_buffer + sizeof(struct dln2_header);
+	len = urb->actual_length - sizeof(struct dln2_header);
+
+	if (handle == DLN2_HANDLE_EVENT) {
+		dln2_run_rx_callbacks(dln2, id, echo, data, len);
+		err = usb_submit_urb(urb, GFP_ATOMIC);
+		if (err < 0)
+			goto out_submit_failed;
+	} else {
+		dln2_rx_transfer(dln2, urb, handle, echo);
+	}
+
+	return;
+
+out:
+	err = usb_submit_urb(urb, GFP_ATOMIC);
+out_submit_failed:
+	if (err < 0)
+		dev_err(dev, "failed to re-submit RX URB: %d\n", err);
+}
+
+static void *dln2_prep_buf(u16 handle, u16 cmd, u16 echo, const void *obuf,
+			   int *obuf_len, gfp_t gfp)
+{
+	int len;
+	void *buf;
+	struct dln2_header *hdr;
+
+	len = *obuf_len + sizeof(*hdr);
+	buf = kmalloc(len, gfp);
+	if (!buf)
+		return NULL;
+
+	hdr = (struct dln2_header *)buf;
+	hdr->id = cpu_to_le16(cmd);
+	hdr->size = cpu_to_le16(len);
+	hdr->echo = cpu_to_le16(echo);
+	hdr->handle = cpu_to_le16(handle);
+
+	memcpy(buf + sizeof(*hdr), obuf, *obuf_len);
+
+	*obuf_len = len;
+
+	return buf;
+}
+
+static int dln2_send_wait(struct dln2_dev *dln2, u16 handle, u16 cmd, u16 echo,
+			  const void *obuf, int obuf_len)
+{
+	int ret = 0;
+	int len = obuf_len;
+	void *buf;
+	int actual;
+
+	buf = dln2_prep_buf(handle, cmd, echo, obuf, &len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = usb_bulk_msg(dln2->usb_dev,
+			   usb_sndbulkpipe(dln2->usb_dev, dln2->ep_out),
+			   buf, len, &actual, DLN2_USB_TIMEOUT);
+
+	kfree(buf);
+
+	return ret;
+}
+
+static int _dln2_transfer(struct dln2_dev *dln2, u16 handle, u16 cmd,
+			  const void *obuf, unsigned obuf_len,
+			  void *ibuf, unsigned *ibuf_len)
+{
+	int ret = 0;
+	u16 result;
+	int rx_slot;
+	unsigned long flags;
+	struct dln2_response *rsp;
+	struct dln2_rx_context *rxc;
+	struct device *dev;
+	const int timeout = DLN2_USB_TIMEOUT * HZ / 1000;
+	struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
+
+	rx_slot = alloc_rx_slot(rxs);
+	if (rx_slot < 0)
+		return rx_slot;
+
+	dev = &dln2->interface->dev;
+
+	ret = dln2_send_wait(dln2, handle, cmd, rx_slot, obuf, obuf_len);
+	if (ret < 0) {
+		free_rx_slot(dln2, rxs, rx_slot);
+		dev_err(dev, "USB write failed: %d", ret);
+		return ret;
+	}
+
+	rxc = &rxs->slots[rx_slot];
+
+	ret = wait_for_completion_interruptible_timeout(&rxc->done, timeout);
+	if (ret <= 0) {
+		if (!ret)
+			ret = -ETIMEDOUT;
+		goto out_free_rx_slot;
+	}
+
+	spin_lock_irqsave(&rxs->lock, flags);
+
+	if (!rxc->urb) {
+		ret = -ECONNRESET;
+		spin_unlock_irqrestore(&rxs->lock, flags);
+		goto out_free_rx_slot;
+	}
+
+	/* if we got here we know that the response header has been checked */
+	rsp = rxc->urb->transfer_buffer;
+
+	spin_unlock_irqrestore(&rxs->lock, flags);
+
+	if (rsp->hdr.size < sizeof(*rsp)) {
+		ret = -EPROTO;
+		goto out_free_rx_slot;
+	}
+
+	result = le16_to_cpu(rsp->result);
+	if (result) {
+		dev_dbg(dev, "%d received response with error %d\n",
+			handle, result);
+		ret = -EREMOTEIO;
+		goto out_free_rx_slot;
+	}
+
+	if (!ibuf) {
+		ret = 0;
+		goto out_free_rx_slot;
+	}
+
+	if (*ibuf_len > rsp->hdr.size - sizeof(*rsp))
+		*ibuf_len = rsp->hdr.size - sizeof(*rsp);
+
+	memcpy(ibuf, rsp + 1, *ibuf_len);
+
+out_free_rx_slot:
+	free_rx_slot(dln2, rxs, rx_slot);
+
+	return ret;
+}
+
+int dln2_transfer(struct platform_device *pdev, u16 cmd,
+		  const void *obuf, unsigned obuf_len,
+		  void *ibuf, unsigned *ibuf_len)
+{
+	struct dln2_platform_data *dln2_pdata;
+	struct dln2_dev *dln2;
+	u16 h;
+
+	dln2 = dev_get_drvdata(pdev->dev.parent);
+	dln2_pdata = dev_get_platdata(&pdev->dev);
+	h = dln2_pdata->handle;
+
+	return _dln2_transfer(dln2, h, cmd, obuf, obuf_len, ibuf, ibuf_len);
+}
+EXPORT_SYMBOL(dln2_transfer);
+
+static int dln2_check_hw(struct dln2_dev *dln2)
+{
+	int ret;
+	__le32 hw_type;
+	int len = sizeof(hw_type);
+
+	ret = _dln2_transfer(dln2, DLN2_HANDLE_CTRL, CMD_GET_DEVICE_VER,
+			     NULL, 0, &hw_type, &len);
+	if (ret < 0)
+		return ret;
+	if (len < sizeof(hw_type))
+		return -EREMOTEIO;
+
+	if (le32_to_cpu(hw_type) != DLN2_HW_ID) {
+		dev_err(&dln2->interface->dev, "Device ID 0x%x not supported",
+			le32_to_cpu(hw_type));
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static int dln2_print_serialno(struct dln2_dev *dln2)
+{
+	int ret;
+	__le32 serial_no;
+	int len = sizeof(serial_no);
+	struct device *dev = &dln2->interface->dev;
+
+	ret = _dln2_transfer(dln2, DLN2_HANDLE_CTRL, CMD_GET_DEVICE_SN, NULL, 0,
+			     &serial_no, &len);
+	if (ret < 0)
+		return ret;
+	if (len < sizeof(serial_no))
+		return -EREMOTEIO;
+
+	dev_info(dev, "Diolan DLN2 serial 0x%x\n", le32_to_cpu(serial_no));
+
+	return 0;
+}
+
+static int dln2_hw_init(struct dln2_dev *dln2)
+{
+	int ret;
+
+	ret = dln2_check_hw(dln2);
+	if (ret < 0)
+		return ret;
+
+	return dln2_print_serialno(dln2);
+}
+
+static void dln2_free_rx_urbs(struct dln2_dev *dln2)
+{
+	int i;
+
+	for (i = 0; i < DLN2_MAX_URBS; i++) {
+		usb_kill_urb(dln2->rx_urb[i]);
+		usb_free_urb(dln2->rx_urb[i]);
+		kfree(dln2->rx_buf[i]);
+	}
+}
+
+static void dln2_free(struct dln2_dev *dln2)
+{
+	dln2_free_rx_urbs(dln2);
+	usb_put_dev(dln2->usb_dev);
+	kfree(dln2);
+}
+
+static int dln2_setup_rx_urbs(struct dln2_dev *dln2,
+			      struct usb_host_interface *hostif)
+{
+	int i;
+	const int rx_max_size = DLN2_RX_BUF_SIZE;
+	struct device *dev = &dln2->interface->dev;
+
+	for (i = 0; i < DLN2_MAX_URBS; i++) {
+		int ret;
+
+		dln2->rx_buf[i] = kmalloc(rx_max_size, GFP_KERNEL);
+		if (!dln2->rx_buf[i])
+			return -ENOMEM;
+
+		dln2->rx_urb[i] = usb_alloc_urb(0, GFP_KERNEL);
+		if (!dln2->rx_urb[i])
+			return -ENOMEM;
+
+		usb_fill_bulk_urb(dln2->rx_urb[i], dln2->usb_dev,
+				  usb_rcvbulkpipe(dln2->usb_dev, dln2->ep_in),
+				  dln2->rx_buf[i], rx_max_size, dln2_rx, dln2);
+
+		ret = usb_submit_urb(dln2->rx_urb[i], GFP_KERNEL);
+		if (ret < 0) {
+			dev_err(dev, "failed to submit RX URB: %d\n", ret);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static struct dln2_platform_data dln2_pdata_gpio = {
+	.handle = DLN2_HANDLE_GPIO,
+};
+
+/* Only one I2C port seems to be supported on current hardware */
+static struct dln2_platform_data dln2_pdata_i2c = {
+	.handle = DLN2_HANDLE_I2C,
+	.port = 0,
+};
+
+static const struct mfd_cell dln2_devs[] = {
+	{
+		.name = "dln2-gpio",
+		.platform_data = &dln2_pdata_gpio,
+		.pdata_size = sizeof(struct dln2_platform_data),
+	},
+	{
+		.name = "dln2-i2c",
+		.platform_data = &dln2_pdata_i2c,
+		.pdata_size = sizeof(struct dln2_platform_data),
+	},
+};
+
+static bool dln2_all_rx_slots_free(struct dln2_mod_rx_slots *rxs)
+{
+	unsigned long flags;
+	int slot;
+
+	spin_lock_irqsave(&rxs->lock, flags);
+	slot = find_first_bit(&rxs->bmap, DLN2_MAX_RX_SLOTS);
+	spin_unlock_irqrestore(&rxs->lock, flags);
+
+	if (slot < DLN2_MAX_RX_SLOTS)
+		return false;
+
+	return true;
+}
+
+static void dln2_stop(struct dln2_dev *dln2)
+{
+	int i, j;
+
+	for (i = 0; i < DLN2_HANDLES; i++) {
+		struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[i];
+		unsigned long flags;
+
+		spin_lock_irqsave(&rxs->lock, flags);
+
+		/* fail further alloc_rx_slot calls */
+		rxs->disconnected = true;
+
+		/* cancel all response waiters */
+		for (j = 0; j < DLN2_MAX_RX_SLOTS; j++) {
+			struct dln2_rx_context *rxc = &rxs->slots[j];
+
+			if (rxc->connected) {
+				rxc->urb = NULL;
+				complete(&rxc->done);
+			}
+		}
+		spin_unlock_irqrestore(&rxs->lock, flags);
+
+		/* wait for callers to release all rx_slots */
+		wait_event(rxs->wq, dln2_all_rx_slots_free(rxs));
+	}
+}
+
+static void dln2_disconnect(struct usb_interface *interface)
+{
+	struct dln2_dev *dln2 = usb_get_intfdata(interface);
+
+	dln2_stop(dln2);
+	mfd_remove_devices(&interface->dev);
+	dln2_free(dln2);
+}
+
+static int dln2_probe(struct usb_interface *interface,
+		      const struct usb_device_id *id)
+{
+	struct usb_host_interface *hostif = interface->cur_altsetting;
+	struct device *dev = &interface->dev;
+	struct dln2_dev *dln2;
+	int ret;
+	int i, j;
+
+	if (hostif->desc.bInterfaceNumber != 0 ||
+	    hostif->desc.bNumEndpoints < 2)
+		return -ENODEV;
+
+	dln2 = kzalloc(sizeof(*dln2), GFP_KERNEL);
+	if (!dln2)
+		return -ENOMEM;
+
+	dln2->ep_out = hostif->endpoint[0].desc.bEndpointAddress;
+	dln2->ep_in = hostif->endpoint[1].desc.bEndpointAddress;
+	dln2->usb_dev = usb_get_dev(interface_to_usbdev(interface));
+	dln2->interface = interface;
+	usb_set_intfdata(interface, dln2);
+
+	for (i = 0; i < DLN2_HANDLES; i++) {
+		init_waitqueue_head(&dln2->mod_rx_slots[i].wq);
+		spin_lock_init(&dln2->mod_rx_slots[i].lock);
+		for (j = 0; j < DLN2_MAX_RX_SLOTS; j++)
+			init_completion(&dln2->mod_rx_slots[i].slots[j].done);
+	}
+
+	spin_lock_init(&dln2->rx_cb_lock);
+	INIT_LIST_HEAD(&dln2->rx_cb_list);
+
+	ret = dln2_setup_rx_urbs(dln2, hostif);
+	if (ret) {
+		dln2_free(dln2);
+		return ret;
+	}
+
+	ret = dln2_hw_init(dln2);
+	if (ret < 0) {
+		dev_err(dev, "failed to initialize hardware\n");
+		goto out_cleanup;
+	}
+
+	ret = mfd_add_devices(dev, -1, dln2_devs, ARRAY_SIZE(dln2_devs),
+			      NULL, 0, NULL);
+	if (ret != 0) {
+		dev_err(dev, "Failed to add mfd devices to core.\n");
+		goto out_cleanup;
+	}
+
+	return 0;
+
+out_cleanup:
+	dln2_free(dln2);
+
+	return ret;
+}
+
+static const struct usb_device_id dln2_table[] = {
+	{ USB_DEVICE(0xa257, 0x2013) },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(usb, dln2_table);
+
+static struct usb_driver dln2_driver = {
+	.name = "usb-dln2",
+	.probe = dln2_probe,
+	.disconnect = dln2_disconnect,
+	.id_table = dln2_table,
+};
+
+module_usb_driver(dln2_driver);
+
+MODULE_AUTHOR("Octavian Purdila <octavian.purdila-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>");
+MODULE_DESCRIPTION("Core driver for the Diolan DLN2 interface adapter");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/mfd/dln2.h b/include/linux/mfd/dln2.h
new file mode 100644
index 0000000..18d5450
--- /dev/null
+++ b/include/linux/mfd/dln2.h
@@ -0,0 +1,67 @@
+#ifndef __LINUX_USB_DLN2_H
+#define __LINUX_USB_DLN2_H
+
+#define DLN2_CMD(cmd, id)		((cmd) | ((id) << 8))
+
+struct dln2_platform_data {
+	u16 handle;		/* sub-driver handle (internally used only) */
+	u8 port;		/* I2C/SPI port */
+};
+
+/**
+ * dln2_rx_cb - event callback function signature
+ *
+ * @pdev - the sub-device that registered this callback
+ * @echo - the echo header field received in the message
+ * @data - the data payload
+ * @len  - the data payload length
+ *
+ * The callback function is called in interrupt context and the data
+ * payload is only valid during the call. If the user needs later
+ * access of the data, it must copy it.
+ */
+
+typedef void (*dln2_rx_cb_t)(struct platform_device *pdev, u16 echo,
+			     const void *data, int len);
+
+/**
+ * dl2n_register_event_cb - register a callback function for an event
+ *
+ * @pdev - the sub-device that registers the callback
+ * @event - the event for which to register a callback
+ * @rx_cb - the callback function
+ *
+ * @return 0 in case of success, negative value in case of error
+ */
+int dln2_register_event_cb(struct platform_device *pdev, u16 event,
+			   dln2_rx_cb_t rx_cb);
+
+/**
+ * dln2_unregister_event_cb - unregister the callback function for an event
+ *
+ * @pdev - the sub-device that registered the callback
+ * @event - the event for which to register a callback
+ */
+void dln2_unregister_event_cb(struct platform_device *pdev, u16 event);
+
+/**
+ * dln2_transfer - issue a DLN2 command and wait for a response and
+ * the associated data
+ *
+ * @pdev - the sub-device which is issuing this transfer
+ * @cmd - the command to be sent to the device
+ * @obuf - the buffer to be sent to the device; can be NULL if the
+ * user doesn't need to transmit data with this command
+ * @obuf_len - the size of the buffer to be sent to the device
+ * @ibuf - any data associated with the response will be copied here;
+ * it can be NULL if the user doesn't need the response data
+ * @ibuf_len - must be initialized to the input buffer size; it will
+ * be modified to indicate the actual data transfered
+ *
+ * @returns 0 for success, negative value for errors
+ */
+int dln2_transfer(struct platform_device *pdev, u16 cmd,
+		  const void *obuf, unsigned obuf_len,
+		  void *ibuf, unsigned *ibuf_len);
+
+#endif
-- 
1.9.1

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[PATCH v5 1/4] mfd: add support for Diolan DLN-2 devices

[Octavian Purdila]

This patch implements the USB part of the Diolan USB-I2C/SPI/GPIO
Master Adapter DLN-2. Details about the device can be found here:

https://www.diolan.com/i2c/i2c_interface.html.

Information about the USB protocol can be found in the Programmer's
Reference Manual [1], see section 1.7.

Because the hardware has a single transmit endpoint and a single
receive endpoint the communication between the various DLN2 drivers
and the hardware will be muxed/demuxed by this driver.

Each DLN2 module will be identified by the handle field within the DLN2
message header. If a DLN2 module issues multiple commands in parallel
they will be identified by the echo counter field in the message header.

The DLN2 modules can use the dln2_transfer() function to issue a
command and wait for its response. They can also register a callback
that is going to be called when a specific event id is generated by
the device (e.g. GPIO interrupts). The device uses handle 0 for
sending events.

[1] https://www.diolan.com/downloads/dln-api-manual.pdf

Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
---
 drivers/mfd/Kconfig      |   9 +
 drivers/mfd/Makefile     |   1 +
 drivers/mfd/dln2.c       | 758 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/mfd/dln2.h |  67 +++++
 4 files changed, 835 insertions(+)
 create mode 100644 drivers/mfd/dln2.c
 create mode 100644 include/linux/mfd/dln2.h

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index de5abf2..7bcf895 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -183,6 +183,15 @@ config MFD_DA9063
 	  Additional drivers must be enabled in order to use the functionality
 	  of the device.
 
+config MFD_DLN2
+	tristate "Diolan DLN2 support"
+	select MFD_CORE
+	depends on USB
+	help
+	  This adds support for Diolan USB-I2C/SPI/GPIO Master Adapter DLN-2.
+	  Additional drivers must be enabled in order to use the functionality
+	  of the device.
+
 config MFD_MC13XXX
 	tristate
 	depends on (SPI_MASTER || I2C)
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index f001487..591988d 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -169,6 +169,7 @@ obj-$(CONFIG_MFD_AS3711)	+= as3711.o
 obj-$(CONFIG_MFD_AS3722)	+= as3722.o
 obj-$(CONFIG_MFD_STW481X)	+= stw481x.o
 obj-$(CONFIG_MFD_IPAQ_MICRO)	+= ipaq-micro.o
+obj-$(CONFIG_MFD_DLN2)		+= dln2.o
 
 intel-soc-pmic-objs		:= intel_soc_pmic_core.o intel_soc_pmic_crc.o
 obj-$(CONFIG_INTEL_SOC_PMIC)	+= intel-soc-pmic.o
diff --git a/drivers/mfd/dln2.c b/drivers/mfd/dln2.c
new file mode 100644
index 0000000..36c53cd
--- /dev/null
+++ b/drivers/mfd/dln2.c
@@ -0,0 +1,758 @@
+/*
+ * Driver for the Diolan DLN-2 USB adapter
+ *
+ * Copyright (c) 2014 Intel Corporation
+ *
+ * Derived from:
+ *  i2c-diolan-u2c.c
+ *  Copyright (c) 2010-2011 Ericsson AB
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+#include <linux/i2c.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/dln2.h>
+#include <linux/rculist.h>
+
+struct dln2_header {
+	__le16 size;
+	__le16 id;
+	__le16 echo;
+	__le16 handle;
+} __packed;
+
+struct dln2_response {
+	struct dln2_header hdr;
+	__le16 result;
+} __packed;
+
+#define DLN2_GENERIC_MODULE_ID		0x00
+#define DLN2_GENERIC_CMD(cmd)		DLN2_CMD(cmd, DLN2_GENERIC_MODULE_ID)
+#define CMD_GET_DEVICE_VER		DLN2_GENERIC_CMD(0x30)
+#define CMD_GET_DEVICE_SN		DLN2_GENERIC_CMD(0x31)
+
+#define DLN2_HW_ID			0x200
+#define DLN2_USB_TIMEOUT		200	/* in ms */
+#define DLN2_MAX_RX_SLOTS		16
+#define DLN2_MAX_URBS			16
+#define DLN2_RX_BUF_SIZE		512
+
+#define DLN2_HANDLE_EVENT		0
+#define DLN2_HANDLE_CTRL		1
+#define DLN2_HANDLE_GPIO		2
+#define DLN2_HANDLE_I2C			3
+#define DLN2_HANDLES			4
+
+
+/*
+ * Receive context used between the receive demultiplexer and the
+ * transfer routine. While sending a request the transfer routine
+ * will look for a free receive context and use it to wait for a
+ * response and to receive the URB and thus the response data.
+ */
+struct dln2_rx_context {
+	/* completion used to wait a response */
+	struct completion done;
+
+	/* if non-NULL the URB contains the response */
+	struct urb *urb;
+
+	/* if true then this context is used to wait for a response */
+	bool connected;
+
+	/* cancel waiting for a response, e.g. on USB disconnect */
+	bool cancel;
+};
+
+/*
+ * Receive contexts for a particular DLN2 module (i2c, gpio, etc.). We
+ * use the handle header field to indentify the module in
+ * dln2_dev.mod_rx_slots and then the echo header field to index the
+ * slots field and find the receive context for a particular
+ * request.
+ */
+struct dln2_mod_rx_slots {
+	/* RX slots bitmap */
+	unsigned long bmap;
+
+	/* used to wait for a free RX slot */
+	wait_queue_head_t wq;
+
+	/* used to wait for an RX operation to complete */
+	struct dln2_rx_context slots[DLN2_MAX_RX_SLOTS];
+
+	/* device has been disconnected */
+	bool disconnected;
+
+	/* avoid races between free_rx_slot, dln2_rx_transfer and dln2_stop */
+	spinlock_t lock;
+};
+
+struct dln2_dev {
+	struct usb_device *usb_dev;
+	struct usb_interface *interface;
+	u8 ep_in;
+	u8 ep_out;
+
+	struct urb *rx_urb[DLN2_MAX_URBS];
+	void *rx_buf[DLN2_MAX_URBS];
+
+	struct dln2_mod_rx_slots mod_rx_slots[DLN2_HANDLES];
+
+	struct list_head rx_cb_list;
+	spinlock_t rx_cb_lock;
+};
+
+static bool find_free_slot(struct dln2_mod_rx_slots *rxs, int *slot)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&rxs->lock, flags);
+
+	if (rxs->disconnected) {
+		*slot = -ECONNRESET;
+		goto out;
+	}
+
+	*slot = find_first_zero_bit(&rxs->bmap, DLN2_MAX_RX_SLOTS);
+
+	if (*slot < DLN2_MAX_RX_SLOTS) {
+		struct dln2_rx_context *rxc = &rxs->slots[*slot];
+
+		set_bit(*slot, &rxs->bmap);
+		rxc->connected = true;
+	}
+
+out:
+	spin_unlock_irqrestore(&rxs->lock, flags);
+
+	return *slot < DLN2_MAX_RX_SLOTS;
+}
+
+static int alloc_rx_slot(struct dln2_mod_rx_slots *rxs)
+{
+	int ret;
+	int slot;
+
+	/*
+	 * No need to timeout here, the wait is bounded by the timeout
+	 * in _dln2_transfer.
+	 */
+	ret = wait_event_interruptible(rxs->wq, find_free_slot(rxs, &slot));
+	if (ret < 0)
+		return ret;
+
+	return slot;
+}
+
+static void free_rx_slot(struct dln2_dev *dln2, struct dln2_mod_rx_slots *rxs,
+			 int slot)
+{
+	struct urb *urb = NULL;
+	unsigned long flags;
+	struct dln2_rx_context *rxc;
+	struct device *dev = &dln2->interface->dev;
+	int ret;
+
+	spin_lock_irqsave(&rxs->lock, flags);
+
+	clear_bit(slot, &rxs->bmap);
+
+	rxc = &rxs->slots[slot];
+	rxc->connected = false;
+	urb = rxc->urb;
+	rxc->urb = NULL;
+	reinit_completion(&rxc->done);
+
+	spin_unlock_irqrestore(&rxs->lock, flags);
+
+	if (urb) {
+		ret = usb_submit_urb(urb, GFP_KERNEL);
+		if (ret < 0)
+			dev_err(dev, "failed to re-submit RX URB: %d\n", ret);
+	}
+
+	wake_up_interruptible(&rxs->wq);
+}
+
+struct dln2_rx_cb_entry {
+	struct list_head list;
+	u16 id;
+	struct platform_device *pdev;
+	dln2_rx_cb_t callback;
+};
+
+int dln2_register_event_cb(struct platform_device *pdev, u16 id,
+			   dln2_rx_cb_t rx_cb)
+{
+	struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
+	struct dln2_rx_cb_entry *i, *new;
+	unsigned long flags;
+	int ret = 0;
+
+	new = kmalloc(sizeof(*new), GFP_KERNEL);
+	if (!new)
+		return -ENOMEM;
+
+	new->id = id;
+	new->callback = rx_cb;
+	new->pdev = pdev;
+
+	spin_lock_irqsave(&dln2->rx_cb_lock, flags);
+
+	list_for_each_entry_rcu(i, &dln2->rx_cb_list, list) {
+		if (i->id == id) {
+			ret = -EBUSY;
+			break;
+		}
+	}
+
+	if (!ret)
+		list_add_rcu(&new->list, &dln2->rx_cb_list);
+
+	spin_unlock_irqrestore(&dln2->rx_cb_lock, flags);
+
+	if (ret)
+		kfree(new);
+
+	return ret;
+}
+EXPORT_SYMBOL(dln2_register_event_cb);
+
+void dln2_unregister_event_cb(struct platform_device *pdev, u16 id)
+{
+	struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
+	struct dln2_rx_cb_entry *i;
+	unsigned long flags;
+	bool found = false;
+
+	spin_lock_irqsave(&dln2->rx_cb_lock, flags);
+
+	list_for_each_entry_rcu(i, &dln2->rx_cb_list, list) {
+		if (i->id == id) {
+			list_del_rcu(&i->list);
+			found = true;
+			break;
+		}
+	}
+
+	spin_unlock_irqrestore(&dln2->rx_cb_lock, flags);
+
+	if (found) {
+		synchronize_rcu();
+		kfree(i);
+	}
+}
+EXPORT_SYMBOL(dln2_unregister_event_cb);
+
+static void dln2_rx_transfer(struct dln2_dev *dln2, struct urb *urb,
+			     u16 handle, u16 rx_slot)
+{
+	struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
+	struct dln2_rx_context *rxc;
+	struct device *dev = &dln2->interface->dev;
+	int err;
+
+	spin_lock(&rxs->lock);
+	rxc = &rxs->slots[rx_slot];
+	if (rxc->connected) {
+		rxc->urb = urb;
+		complete(&rxc->done);
+	} else {
+		dev_warn(dev, "dropping response %d/%d", handle, rx_slot);
+		err = usb_submit_urb(urb, GFP_ATOMIC);
+		if (err < 0)
+			dev_err(dev, "failed to re-submit RX URB: %d\n", err);
+	}
+	spin_unlock(&rxs->lock);
+}
+
+static void dln2_run_rx_callbacks(struct dln2_dev *dln2, u16 id, u16 echo,
+				  void *data, int len)
+{
+	struct dln2_rx_cb_entry *i;
+
+	rcu_read_lock();
+
+	list_for_each_entry_rcu(i, &dln2->rx_cb_list, list)
+		if (i->id == id)
+			i->callback(i->pdev, echo, data, len);
+
+	rcu_read_unlock();
+}
+
+static void dln2_rx(struct urb *urb)
+{
+	int err;
+	struct dln2_dev *dln2 = urb->context;
+	struct dln2_header *hdr = urb->transfer_buffer;
+	struct device *dev = &dln2->interface->dev;
+	u16 id, echo, handle, size;
+	u8 *data;
+	int len;
+
+	switch (urb->status) {
+	case 0:
+		/* success */
+		break;
+	case -ECONNRESET:
+	case -ENOENT:
+	case -ESHUTDOWN:
+	case -EPIPE:
+		/* this urb is terminated, clean up */
+		dev_dbg(dev, "urb shutting down with status %d\n", urb->status);
+		return;
+	default:
+		dev_dbg(dev, "nonzero urb status received %d\n", urb->status);
+		goto out;
+	}
+
+	if (urb->actual_length < sizeof(struct dln2_header)) {
+		dev_err(dev, "short response: %d\n", urb->actual_length);
+		goto out;
+	}
+
+	handle = le16_to_cpu(hdr->handle);
+	id = le16_to_cpu(hdr->id);
+	echo = le16_to_cpu(hdr->echo);
+	size = le16_to_cpu(hdr->size);
+
+	if (size != urb->actual_length) {
+		dev_err(dev, "size mismatch: handle %x cmd %x echo %x size %d actual %d\n",
+			handle, id, echo, size, urb->actual_length);
+		goto out;
+	}
+
+	if (handle >= DLN2_HANDLES) {
+		dev_warn(dev, "RX: invalid handle %d\n", handle);
+		goto out;
+	}
+
+	data = urb->transfer_buffer + sizeof(struct dln2_header);
+	len = urb->actual_length - sizeof(struct dln2_header);
+
+	if (handle == DLN2_HANDLE_EVENT) {
+		dln2_run_rx_callbacks(dln2, id, echo, data, len);
+		err = usb_submit_urb(urb, GFP_ATOMIC);
+		if (err < 0)
+			goto out_submit_failed;
+	} else {
+		dln2_rx_transfer(dln2, urb, handle, echo);
+	}
+
+	return;
+
+out:
+	err = usb_submit_urb(urb, GFP_ATOMIC);
+out_submit_failed:
+	if (err < 0)
+		dev_err(dev, "failed to re-submit RX URB: %d\n", err);
+}
+
+static void *dln2_prep_buf(u16 handle, u16 cmd, u16 echo, const void *obuf,
+			   int *obuf_len, gfp_t gfp)
+{
+	int len;
+	void *buf;
+	struct dln2_header *hdr;
+
+	len = *obuf_len + sizeof(*hdr);
+	buf = kmalloc(len, gfp);
+	if (!buf)
+		return NULL;
+
+	hdr = (struct dln2_header *)buf;
+	hdr->id = cpu_to_le16(cmd);
+	hdr->size = cpu_to_le16(len);
+	hdr->echo = cpu_to_le16(echo);
+	hdr->handle = cpu_to_le16(handle);
+
+	memcpy(buf + sizeof(*hdr), obuf, *obuf_len);
+
+	*obuf_len = len;
+
+	return buf;
+}
+
+static int dln2_send_wait(struct dln2_dev *dln2, u16 handle, u16 cmd, u16 echo,
+			  const void *obuf, int obuf_len)
+{
+	int ret = 0;
+	int len = obuf_len;
+	void *buf;
+	int actual;
+
+	buf = dln2_prep_buf(handle, cmd, echo, obuf, &len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = usb_bulk_msg(dln2->usb_dev,
+			   usb_sndbulkpipe(dln2->usb_dev, dln2->ep_out),
+			   buf, len, &actual, DLN2_USB_TIMEOUT);
+
+	kfree(buf);
+
+	return ret;
+}
+
+static int _dln2_transfer(struct dln2_dev *dln2, u16 handle, u16 cmd,
+			  const void *obuf, unsigned obuf_len,
+			  void *ibuf, unsigned *ibuf_len)
+{
+	int ret = 0;
+	u16 result;
+	int rx_slot;
+	unsigned long flags;
+	struct dln2_response *rsp;
+	struct dln2_rx_context *rxc;
+	struct device *dev;
+	const int timeout = DLN2_USB_TIMEOUT * HZ / 1000;
+	struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
+
+	rx_slot = alloc_rx_slot(rxs);
+	if (rx_slot < 0)
+		return rx_slot;
+
+	dev = &dln2->interface->dev;
+
+	ret = dln2_send_wait(dln2, handle, cmd, rx_slot, obuf, obuf_len);
+	if (ret < 0) {
+		free_rx_slot(dln2, rxs, rx_slot);
+		dev_err(dev, "USB write failed: %d", ret);
+		return ret;
+	}
+
+	rxc = &rxs->slots[rx_slot];
+
+	ret = wait_for_completion_interruptible_timeout(&rxc->done, timeout);
+	if (ret <= 0) {
+		if (!ret)
+			ret = -ETIMEDOUT;
+		goto out_free_rx_slot;
+	}
+
+	spin_lock_irqsave(&rxs->lock, flags);
+
+	if (!rxc->urb) {
+		ret = -ECONNRESET;
+		spin_unlock_irqrestore(&rxs->lock, flags);
+		goto out_free_rx_slot;
+	}
+
+	/* if we got here we know that the response header has been checked */
+	rsp = rxc->urb->transfer_buffer;
+
+	spin_unlock_irqrestore(&rxs->lock, flags);
+
+	if (rsp->hdr.size < sizeof(*rsp)) {
+		ret = -EPROTO;
+		goto out_free_rx_slot;
+	}
+
+	result = le16_to_cpu(rsp->result);
+	if (result) {
+		dev_dbg(dev, "%d received response with error %d\n",
+			handle, result);
+		ret = -EREMOTEIO;
+		goto out_free_rx_slot;
+	}
+
+	if (!ibuf) {
+		ret = 0;
+		goto out_free_rx_slot;
+	}
+
+	if (*ibuf_len > rsp->hdr.size - sizeof(*rsp))
+		*ibuf_len = rsp->hdr.size - sizeof(*rsp);
+
+	memcpy(ibuf, rsp + 1, *ibuf_len);
+
+out_free_rx_slot:
+	free_rx_slot(dln2, rxs, rx_slot);
+
+	return ret;
+}
+
+int dln2_transfer(struct platform_device *pdev, u16 cmd,
+		  const void *obuf, unsigned obuf_len,
+		  void *ibuf, unsigned *ibuf_len)
+{
+	struct dln2_platform_data *dln2_pdata;
+	struct dln2_dev *dln2;
+	u16 h;
+
+	dln2 = dev_get_drvdata(pdev->dev.parent);
+	dln2_pdata = dev_get_platdata(&pdev->dev);
+	h = dln2_pdata->handle;
+
+	return _dln2_transfer(dln2, h, cmd, obuf, obuf_len, ibuf, ibuf_len);
+}
+EXPORT_SYMBOL(dln2_transfer);
+
+static int dln2_check_hw(struct dln2_dev *dln2)
+{
+	int ret;
+	__le32 hw_type;
+	int len = sizeof(hw_type);
+
+	ret = _dln2_transfer(dln2, DLN2_HANDLE_CTRL, CMD_GET_DEVICE_VER,
+			     NULL, 0, &hw_type, &len);
+	if (ret < 0)
+		return ret;
+	if (len < sizeof(hw_type))
+		return -EREMOTEIO;
+
+	if (le32_to_cpu(hw_type) != DLN2_HW_ID) {
+		dev_err(&dln2->interface->dev, "Device ID 0x%x not supported",
+			le32_to_cpu(hw_type));
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static int dln2_print_serialno(struct dln2_dev *dln2)
+{
+	int ret;
+	__le32 serial_no;
+	int len = sizeof(serial_no);
+	struct device *dev = &dln2->interface->dev;
+
+	ret = _dln2_transfer(dln2, DLN2_HANDLE_CTRL, CMD_GET_DEVICE_SN, NULL, 0,
+			     &serial_no, &len);
+	if (ret < 0)
+		return ret;
+	if (len < sizeof(serial_no))
+		return -EREMOTEIO;
+
+	dev_info(dev, "Diolan DLN2 serial 0x%x\n", le32_to_cpu(serial_no));
+
+	return 0;
+}
+
+static int dln2_hw_init(struct dln2_dev *dln2)
+{
+	int ret;
+
+	ret = dln2_check_hw(dln2);
+	if (ret < 0)
+		return ret;
+
+	return dln2_print_serialno(dln2);
+}
+
+static void dln2_free_rx_urbs(struct dln2_dev *dln2)
+{
+	int i;
+
+	for (i = 0; i < DLN2_MAX_URBS; i++) {
+		usb_kill_urb(dln2->rx_urb[i]);
+		usb_free_urb(dln2->rx_urb[i]);
+		kfree(dln2->rx_buf[i]);
+	}
+}
+
+static void dln2_free(struct dln2_dev *dln2)
+{
+	dln2_free_rx_urbs(dln2);
+	usb_put_dev(dln2->usb_dev);
+	kfree(dln2);
+}
+
+static int dln2_setup_rx_urbs(struct dln2_dev *dln2,
+			      struct usb_host_interface *hostif)
+{
+	int i;
+	const int rx_max_size = DLN2_RX_BUF_SIZE;
+	struct device *dev = &dln2->interface->dev;
+
+	for (i = 0; i < DLN2_MAX_URBS; i++) {
+		int ret;
+
+		dln2->rx_buf[i] = kmalloc(rx_max_size, GFP_KERNEL);
+		if (!dln2->rx_buf[i])
+			return -ENOMEM;
+
+		dln2->rx_urb[i] = usb_alloc_urb(0, GFP_KERNEL);
+		if (!dln2->rx_urb[i])
+			return -ENOMEM;
+
+		usb_fill_bulk_urb(dln2->rx_urb[i], dln2->usb_dev,
+				  usb_rcvbulkpipe(dln2->usb_dev, dln2->ep_in),
+				  dln2->rx_buf[i], rx_max_size, dln2_rx, dln2);
+
+		ret = usb_submit_urb(dln2->rx_urb[i], GFP_KERNEL);
+		if (ret < 0) {
+			dev_err(dev, "failed to submit RX URB: %d\n", ret);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static struct dln2_platform_data dln2_pdata_gpio = {
+	.handle = DLN2_HANDLE_GPIO,
+};
+
+/* Only one I2C port seems to be supported on current hardware */
+static struct dln2_platform_data dln2_pdata_i2c = {
+	.handle = DLN2_HANDLE_I2C,
+	.port = 0,
+};
+
+static const struct mfd_cell dln2_devs[] = {
+	{
+		.name = "dln2-gpio",
+		.platform_data = &dln2_pdata_gpio,
+		.pdata_size = sizeof(struct dln2_platform_data),
+	},
+	{
+		.name = "dln2-i2c",
+		.platform_data = &dln2_pdata_i2c,
+		.pdata_size = sizeof(struct dln2_platform_data),
+	},
+};
+
+static bool dln2_all_rx_slots_free(struct dln2_mod_rx_slots *rxs)
+{
+	unsigned long flags;
+	int slot;
+
+	spin_lock_irqsave(&rxs->lock, flags);
+	slot = find_first_bit(&rxs->bmap, DLN2_MAX_RX_SLOTS);
+	spin_unlock_irqrestore(&rxs->lock, flags);
+
+	if (slot < DLN2_MAX_RX_SLOTS)
+		return false;
+
+	return true;
+}
+
+static void dln2_stop(struct dln2_dev *dln2)
+{
+	int i, j;
+
+	for (i = 0; i < DLN2_HANDLES; i++) {
+		struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[i];
+		unsigned long flags;
+
+		spin_lock_irqsave(&rxs->lock, flags);
+
+		/* fail further alloc_rx_slot calls */
+		rxs->disconnected = true;
+
+		/* cancel all response waiters */
+		for (j = 0; j < DLN2_MAX_RX_SLOTS; j++) {
+			struct dln2_rx_context *rxc = &rxs->slots[j];
+
+			if (rxc->connected) {
+				rxc->urb = NULL;
+				complete(&rxc->done);
+			}
+		}
+		spin_unlock_irqrestore(&rxs->lock, flags);
+
+		/* wait for callers to release all rx_slots */
+		wait_event(rxs->wq, dln2_all_rx_slots_free(rxs));
+	}
+}
+
+static void dln2_disconnect(struct usb_interface *interface)
+{
+	struct dln2_dev *dln2 = usb_get_intfdata(interface);
+
+	dln2_stop(dln2);
+	mfd_remove_devices(&interface->dev);
+	dln2_free(dln2);
+}
+
+static int dln2_probe(struct usb_interface *interface,
+		      const struct usb_device_id *id)
+{
+	struct usb_host_interface *hostif = interface->cur_altsetting;
+	struct device *dev = &interface->dev;
+	struct dln2_dev *dln2;
+	int ret;
+	int i, j;
+
+	if (hostif->desc.bInterfaceNumber != 0 ||
+	    hostif->desc.bNumEndpoints < 2)
+		return -ENODEV;
+
+	dln2 = kzalloc(sizeof(*dln2), GFP_KERNEL);
+	if (!dln2)
+		return -ENOMEM;
+
+	dln2->ep_out = hostif->endpoint[0].desc.bEndpointAddress;
+	dln2->ep_in = hostif->endpoint[1].desc.bEndpointAddress;
+	dln2->usb_dev = usb_get_dev(interface_to_usbdev(interface));
+	dln2->interface = interface;
+	usb_set_intfdata(interface, dln2);
+
+	for (i = 0; i < DLN2_HANDLES; i++) {
+		init_waitqueue_head(&dln2->mod_rx_slots[i].wq);
+		spin_lock_init(&dln2->mod_rx_slots[i].lock);
+		for (j = 0; j < DLN2_MAX_RX_SLOTS; j++)
+			init_completion(&dln2->mod_rx_slots[i].slots[j].done);
+	}
+
+	spin_lock_init(&dln2->rx_cb_lock);
+	INIT_LIST_HEAD(&dln2->rx_cb_list);
+
+	ret = dln2_setup_rx_urbs(dln2, hostif);
+	if (ret) {
+		dln2_free(dln2);
+		return ret;
+	}
+
+	ret = dln2_hw_init(dln2);
+	if (ret < 0) {
+		dev_err(dev, "failed to initialize hardware\n");
+		goto out_cleanup;
+	}
+
+	ret = mfd_add_devices(dev, -1, dln2_devs, ARRAY_SIZE(dln2_devs),
+			      NULL, 0, NULL);
+	if (ret != 0) {
+		dev_err(dev, "Failed to add mfd devices to core.\n");
+		goto out_cleanup;
+	}
+
+	return 0;
+
+out_cleanup:
+	dln2_free(dln2);
+
+	return ret;
+}
+
+static const struct usb_device_id dln2_table[] = {
+	{ USB_DEVICE(0xa257, 0x2013) },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(usb, dln2_table);
+
+static struct usb_driver dln2_driver = {
+	.name = "usb-dln2",
+	.probe = dln2_probe,
+	.disconnect = dln2_disconnect,
+	.id_table = dln2_table,
+};
+
+module_usb_driver(dln2_driver);
+
+MODULE_AUTHOR("Octavian Purdila <octavian.purdila@intel.com>");
+MODULE_DESCRIPTION("Core driver for the Diolan DLN2 interface adapter");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/mfd/dln2.h b/include/linux/mfd/dln2.h
new file mode 100644
index 0000000..18d5450
--- /dev/null
+++ b/include/linux/mfd/dln2.h
@@ -0,0 +1,67 @@
+#ifndef __LINUX_USB_DLN2_H
+#define __LINUX_USB_DLN2_H
+
+#define DLN2_CMD(cmd, id)		((cmd) | ((id) << 8))
+
+struct dln2_platform_data {
+	u16 handle;		/* sub-driver handle (internally used only) */
+	u8 port;		/* I2C/SPI port */
+};
+
+/**
+ * dln2_rx_cb - event callback function signature
+ *
+ * @pdev - the sub-device that registered this callback
+ * @echo - the echo header field received in the message
+ * @data - the data payload
+ * @len  - the data payload length
+ *
+ * The callback function is called in interrupt context and the data
+ * payload is only valid during the call. If the user needs later
+ * access of the data, it must copy it.
+ */
+
+typedef void (*dln2_rx_cb_t)(struct platform_device *pdev, u16 echo,
+			     const void *data, int len);
+
+/**
+ * dl2n_register_event_cb - register a callback function for an event
+ *
+ * @pdev - the sub-device that registers the callback
+ * @event - the event for which to register a callback
+ * @rx_cb - the callback function
+ *
+ * @return 0 in case of success, negative value in case of error
+ */
+int dln2_register_event_cb(struct platform_device *pdev, u16 event,
+			   dln2_rx_cb_t rx_cb);
+
+/**
+ * dln2_unregister_event_cb - unregister the callback function for an event
+ *
+ * @pdev - the sub-device that registered the callback
+ * @event - the event for which to register a callback
+ */
+void dln2_unregister_event_cb(struct platform_device *pdev, u16 event);
+
+/**
+ * dln2_transfer - issue a DLN2 command and wait for a response and
+ * the associated data
+ *
+ * @pdev - the sub-device which is issuing this transfer
+ * @cmd - the command to be sent to the device
+ * @obuf - the buffer to be sent to the device; can be NULL if the
+ * user doesn't need to transmit data with this command
+ * @obuf_len - the size of the buffer to be sent to the device
+ * @ibuf - any data associated with the response will be copied here;
+ * it can be NULL if the user doesn't need the response data
+ * @ibuf_len - must be initialized to the input buffer size; it will
+ * be modified to indicate the actual data transfered
+ *
+ * @returns 0 for success, negative value for errors
+ */
+int dln2_transfer(struct platform_device *pdev, u16 cmd,
+		  const void *obuf, unsigned obuf_len,
+		  void *ibuf, unsigned *ibuf_len);
+
+#endif
-- 
1.9.1

[PATCH v5 2/4] i2c: add support for Diolan DLN-2 USB-I2C adapter

[Octavian Purdila]

From: Laurentiu Palcu <laurentiu.palcu@intel.com>

This patch adds support for the Diolan DLN-2 I2C master module. Due
to hardware limitations it does not support SMBUS quick commands.

Information about the USB protocol interface can be found in the
Programmer's Reference Manual [1], see section 6.2.2 for the I2C
master module commands and responses.

[1] https://www.diolan.com/downloads/dln-api-manual.pdf

Signed-off-by: Laurentiu Palcu <laurentiu.palcu@intel.com>
Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
---
 drivers/i2c/busses/Kconfig    |  10 ++
 drivers/i2c/busses/Makefile   |   1 +
 drivers/i2c/busses/i2c-dln2.c | 383 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 394 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-dln2.c

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 2ac87fa..6afc17e 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -1021,4 +1021,14 @@ config SCx200_ACB
 	  This support is also available as a module.  If so, the module
 	  will be called scx200_acb.
 
+config I2C_DLN2
+       tristate "Diolan DLN-2 USB I2C adapter"
+       depends on MFD_DLN2
+       help
+         If you say yes to this option, support will be included for Diolan
+         DLN2, a USB to I2C interface.
+
+         This driver can also be built as a module.  If so, the module
+         will be called i2c-dln2.
+
 endmenu
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 49bf07e..3118fea 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -100,5 +100,6 @@ obj-$(CONFIG_I2C_ELEKTOR)	+= i2c-elektor.o
 obj-$(CONFIG_I2C_PCA_ISA)	+= i2c-pca-isa.o
 obj-$(CONFIG_I2C_SIBYTE)	+= i2c-sibyte.o
 obj-$(CONFIG_SCx200_ACB)	+= scx200_acb.o
+obj-$(CONFIG_I2C_DLN2)		+= i2c-dln2.o
 
 ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG
diff --git a/drivers/i2c/busses/i2c-dln2.c b/drivers/i2c/busses/i2c-dln2.c
new file mode 100644
index 0000000..21ad6dc
--- /dev/null
+++ b/drivers/i2c/busses/i2c-dln2.c
@@ -0,0 +1,383 @@
+/*
+ * Driver for the Diolan DLN-2 USB-I2C adapter
+ *
+ * Copyright (c) 2014 Intel Corporation
+ *
+ * Derived from:
+ *  i2c-diolan-u2c.c
+ *  Copyright (c) 2010-2011 Ericsson AB
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/dln2.h>
+
+#define DLN2_I2C_MODULE_ID		0x03
+#define DLN2_I2C_CMD(cmd)		DLN2_CMD(cmd, DLN2_I2C_MODULE_ID)
+
+/* I2C commands */
+#define DLN2_I2C_GET_PORT_COUNT		DLN2_I2C_CMD(0x00)
+#define DLN2_I2C_ENABLE			DLN2_I2C_CMD(0x01)
+#define DLN2_I2C_DISABLE		DLN2_I2C_CMD(0x02)
+#define DLN2_I2C_IS_ENABLED		DLN2_I2C_CMD(0x03)
+#define DLN2_I2C_SET_FREQUENCY		DLN2_I2C_CMD(0x04)
+#define DLN2_I2C_GET_FREQUENCY		DLN2_I2C_CMD(0x05)
+#define DLN2_I2C_WRITE			DLN2_I2C_CMD(0x06)
+#define DLN2_I2C_READ			DLN2_I2C_CMD(0x07)
+#define DLN2_I2C_SCAN_DEVICES		DLN2_I2C_CMD(0x08)
+#define DLN2_I2C_PULLUP_ENABLE		DLN2_I2C_CMD(0x09)
+#define DLN2_I2C_PULLUP_DISABLE		DLN2_I2C_CMD(0x0A)
+#define DLN2_I2C_PULLUP_IS_ENABLED	DLN2_I2C_CMD(0x0B)
+#define DLN2_I2C_TRANSFER		DLN2_I2C_CMD(0x0C)
+#define DLN2_I2C_SET_MAX_REPLY_COUNT	DLN2_I2C_CMD(0x0D)
+#define DLN2_I2C_GET_MAX_REPLY_COUNT	DLN2_I2C_CMD(0x0E)
+#define DLN2_I2C_GET_MIN_FREQUENCY	DLN2_I2C_CMD(0x40)
+#define DLN2_I2C_GET_MAX_FREQUENCY	DLN2_I2C_CMD(0x41)
+
+#define DLN2_I2C_FREQ_STD		100000
+
+#define DLN2_I2C_MAX_XFER_SIZE		256
+
+struct dln2_i2c {
+	struct platform_device *pdev;
+	struct i2c_adapter adapter;
+	u32 freq;
+	u32 min_freq;
+	u32 max_freq;
+	/*
+	 * Buffer to hold the packet for read or write transfers. One
+	 * is enough since we can't have multiple transfers in
+	 * parallel on the i2c adapter.
+	 */
+	union {
+		struct {
+			u8 port;
+			u8 addr;
+			u8 mem_addr_len;
+			__le32 mem_addr;
+			__le16 buf_len;
+			u8 buf[DLN2_I2C_MAX_XFER_SIZE];
+		} __packed tx;
+		struct {
+			__le16 buf_len;
+			u8 buf[DLN2_I2C_MAX_XFER_SIZE];
+		} __packed rx;
+	} *buf;
+};
+
+static int dln2_i2c_enable(struct dln2_i2c *dln2, bool enable)
+{
+	struct dln2_platform_data *pdata = dev_get_platdata(&dln2->pdev->dev);
+	int ret;
+	u8 port;
+	u16 cmd;
+
+	port = pdata->port;
+
+	if (enable)
+		cmd = DLN2_I2C_ENABLE;
+	else
+		cmd = DLN2_I2C_DISABLE;
+
+	ret = dln2_transfer(dln2->pdev, cmd, &port, sizeof(port), NULL, NULL);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int dln2_i2c_set_frequency(struct dln2_i2c *dln2, u32 freq)
+{
+	int ret;
+	struct tx_data {
+		u8 port;
+		__le32 freq;
+	} __packed tx;
+	struct dln2_platform_data *pdata = dev_get_platdata(&dln2->pdev->dev);
+
+	tx.port = pdata->port;
+	tx.freq = cpu_to_le32(freq);
+
+	ret = dln2_transfer(dln2->pdev, DLN2_I2C_SET_FREQUENCY, &tx, sizeof(tx),
+			    NULL, NULL);
+	if (ret < 0)
+		return ret;
+
+	dln2->freq = freq;
+
+	return 0;
+}
+
+static int dln2_i2c_get_freq(struct dln2_i2c *dln2, u16 cmd, u32 *res)
+{
+	int ret;
+	struct dln2_platform_data *pdata = dev_get_platdata(&dln2->pdev->dev);
+	u8 port = pdata->port;
+	__le32 freq;
+	unsigned len = sizeof(freq);
+
+	ret = dln2_transfer(dln2->pdev, cmd, &port, sizeof(port),
+			    &freq, &len);
+	if (ret < 0)
+		return ret;
+	if (len < sizeof(freq))
+		return -EPROTO;
+
+	*res = le32_to_cpu(freq);
+
+	return 0;
+}
+
+static int dln2_i2c_setup(struct dln2_i2c *dln2)
+{
+	int ret;
+
+	ret = dln2_i2c_enable(dln2, false);
+	if (ret < 0)
+		return ret;
+
+	ret = dln2_i2c_get_freq(dln2, DLN2_I2C_GET_MIN_FREQUENCY,
+				&dln2->min_freq);
+	if (ret < 0)
+		return 0;
+
+	ret = dln2_i2c_get_freq(dln2, DLN2_I2C_GET_MAX_FREQUENCY,
+				&dln2->max_freq);
+	if (ret < 0)
+		return 0;
+
+	ret = dln2_i2c_set_frequency(dln2, DLN2_I2C_FREQ_STD);
+	if (ret < 0)
+		return ret;
+
+	ret = dln2_i2c_enable(dln2, true);
+
+	return ret;
+}
+
+static int dln2_i2c_write(struct dln2_i2c *dln2, u8 addr,
+			  u8 *data, u16 data_len)
+{
+	struct dln2_platform_data *pdata = dev_get_platdata(&dln2->pdev->dev);
+	int ret;
+	unsigned len;
+
+	dln2->buf->tx.port = pdata->port;
+	dln2->buf->tx.addr = addr;
+	dln2->buf->tx.mem_addr_len = 0;
+	dln2->buf->tx.mem_addr = 0;
+	dln2->buf->tx.buf_len = cpu_to_le16(data_len);
+	memcpy(dln2->buf->tx.buf, data, data_len);
+
+	len = sizeof(dln2->buf->tx) + data_len - DLN2_I2C_MAX_XFER_SIZE;
+	ret = dln2_transfer(dln2->pdev, DLN2_I2C_WRITE, &dln2->buf->tx, len,
+			    NULL, NULL);
+	if (ret < 0)
+		return ret;
+
+	return data_len;
+}
+
+static int dln2_i2c_read(struct dln2_i2c *dln2, u16 addr, u8 *data,
+			 u16 data_len)
+{
+	struct dln2_platform_data *pdata = dev_get_platdata(&dln2->pdev->dev);
+	int ret;
+	struct {
+		u8 port;
+		u8 addr;
+		u8 mem_addr_len;
+		__le32 mem_addr;
+		__le16 buf_len;
+	} __packed tx;
+	unsigned rx_len;
+
+	tx.port = pdata->port;
+	tx.addr = addr;
+	tx.mem_addr_len = 0;
+	tx.mem_addr = 0;
+	tx.buf_len = cpu_to_le16(data_len);
+
+	rx_len = sizeof(dln2->buf->rx);
+
+	ret = dln2_transfer(dln2->pdev, DLN2_I2C_READ, &tx, sizeof(tx),
+			    &dln2->buf->rx, &rx_len);
+	if (ret < 0)
+		return ret;
+	if (rx_len < sizeof(dln2->buf->rx.buf_len) + data_len)
+		return -EPROTO;
+	if (le16_to_cpu(dln2->buf->rx.buf_len) != data_len)
+		return -EPROTO;
+
+	memcpy(data, dln2->buf->rx.buf, data_len);
+
+	return data_len;
+}
+
+static int dln2_i2c_xfer(struct i2c_adapter *adapter,
+			 struct i2c_msg *msgs, int num)
+{
+	struct dln2_i2c *dln2 = i2c_get_adapdata(adapter);
+	struct i2c_msg *pmsg;
+	int i;
+
+	for (i = 0; i < num; i++) {
+		int ret;
+
+		pmsg = &msgs[i];
+
+		if (pmsg->len > DLN2_I2C_MAX_XFER_SIZE)
+			return -EINVAL;
+
+		if (pmsg->flags & I2C_M_RD) {
+			ret = dln2_i2c_read(dln2, pmsg->addr, pmsg->buf,
+					    pmsg->len);
+			if (ret < 0)
+				return ret;
+
+			pmsg->len = ret;
+		} else {
+			ret = dln2_i2c_write(dln2, pmsg->addr, pmsg->buf,
+					     pmsg->len);
+			if (ret != pmsg->len)
+				return -EPROTO;
+		}
+	}
+
+	return num;
+}
+
+static u32 dln2_i2c_func(struct i2c_adapter *a)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA |
+		I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
+		I2C_FUNC_SMBUS_I2C_BLOCK;
+}
+
+static const struct i2c_algorithm dln2_i2c_usb_algorithm = {
+	.master_xfer = dln2_i2c_xfer,
+	.functionality = dln2_i2c_func,
+};
+
+static ssize_t dln2_i2c_freq_show(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	struct dln2_i2c *dln2 = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", dln2->freq);
+}
+
+static ssize_t dln2_i2c_freq_store(struct device *dev,
+				   struct device_attribute *attr,
+				   const char *buf, size_t count)
+{
+	struct dln2_i2c *dln2 = dev_get_drvdata(dev);
+	unsigned long freq;
+	int ret;
+
+	if (kstrtoul(buf, 0, &freq) || freq < dln2->min_freq ||
+	    freq > dln2->max_freq)
+		return -EINVAL;
+
+	ret = dln2_i2c_enable(dln2, false);
+	if (ret < 0)
+		return ret;
+
+	ret = dln2_i2c_set_frequency(dln2, freq);
+	if (ret < 0)
+		return ret;
+
+	ret = dln2_i2c_enable(dln2, true);
+
+	return count;
+}
+
+static DEVICE_ATTR_RW(dln2_i2c_freq);
+static struct attribute *dln2_i2c_freq_attrs[] = {
+	&dev_attr_dln2_i2c_freq.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(dln2_i2c_freq);
+
+static int dln2_i2c_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct dln2_i2c *dln2;
+	struct device *dev = &pdev->dev;
+	struct dln2_platform_data *pdata = dev_get_platdata(&pdev->dev);
+
+	dln2 = devm_kzalloc(dev, sizeof(*dln2), GFP_KERNEL);
+	if (!dln2)
+		return -ENOMEM;
+
+	dln2->buf = devm_kmalloc(dev, sizeof(*dln2->buf), GFP_KERNEL);
+	if (!dln2->buf)
+		return -ENOMEM;
+
+	dln2->pdev = pdev;
+
+	/* setup i2c adapter description */
+	dln2->adapter.owner = THIS_MODULE;
+	dln2->adapter.class = I2C_CLASS_HWMON;
+	dln2->adapter.algo = &dln2_i2c_usb_algorithm;
+	dln2->adapter.dev.parent = dev;
+	dln2->adapter.dev.groups = dln2_i2c_freq_groups;
+	i2c_set_adapdata(&dln2->adapter, dln2);
+	snprintf(dln2->adapter.name, sizeof(dln2->adapter.name), "%s-%s-%d",
+		 "dln2-i2c", dev_name(pdev->dev.parent), pdata->port);
+
+	platform_set_drvdata(pdev, dln2);
+
+	/* initialize the i2c interface */
+	ret = dln2_i2c_setup(dln2);
+	if (ret < 0) {
+		dev_err(dev, "failed to initialize adapter: %d\n", ret);
+		return ret;
+	}
+
+	/* and finally attach to i2c layer */
+	ret = i2c_add_adapter(&dln2->adapter);
+	if (ret < 0) {
+		dev_err(dev, "failed to add I2C adapter: %d\n", ret);
+		goto out_disable;
+	}
+
+	return 0;
+
+out_disable:
+	dln2_i2c_enable(dln2, false);
+
+	return ret;
+}
+
+static int dln2_i2c_remove(struct platform_device *pdev)
+{
+	struct dln2_i2c *dln2 = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&dln2->adapter);
+	dln2_i2c_enable(dln2, false);
+
+	return 0;
+}
+
+static struct platform_driver dln2_i2c_driver = {
+	.driver.name	= "dln2-i2c",
+	.driver.owner	= THIS_MODULE,
+	.probe		= dln2_i2c_probe,
+	.remove		= dln2_i2c_remove,
+};
+
+module_platform_driver(dln2_i2c_driver);
+
+MODULE_AUTHOR("Laurentiu Palcu <laurentiu.palcu@intel.com>");
+MODULE_DESCRIPTION("Driver for the Diolan DLN2 I2C master interface");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:dln2-i2c");
-- 
1.9.1

[PATCH v5 3/4] gpiolib: add irq_not_threaded flag to gpio_chip

[Octavian Purdila]

Some GPIO chips (e.g. the DLN2 USB adapter) have blocking get/set
operation but do not need a threaded irq handler.

Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
---
 drivers/gpio/gpiolib.c      | 2 +-
 include/linux/gpio/driver.h | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 15cc0bb..3fa7e73 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -447,7 +447,7 @@ static int gpiochip_irq_map(struct irq_domain *d, unsigned int irq,
 	irq_set_lockdep_class(irq, &gpiochip_irq_lock_class);
 	irq_set_chip_and_handler(irq, chip->irqchip, chip->irq_handler);
 	/* Chips that can sleep need nested thread handlers */
-	if (chip->can_sleep)
+	if (chip->can_sleep && !chip->irq_not_threaded)
 		irq_set_nested_thread(irq, 1);
 #ifdef CONFIG_ARM
 	set_irq_flags(irq, IRQF_VALID);
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index e78a237..44161ac 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -56,6 +56,8 @@ struct seq_file;
  *	as the chip access may sleep when e.g. reading out the IRQ status
  *	registers.
  * @exported: flags if the gpiochip is exported for use from sysfs. Private.
+ * @irq_not_threaded: flag must be set if @can_sleep is set but the
+ *	IRQs don't need to be threaded
  *
  * A gpio_chip can help platforms abstract various sources of GPIOs so
  * they can all be accessed through a common programing interface.
@@ -101,6 +103,7 @@ struct gpio_chip {
 	struct gpio_desc	*desc;
 	const char		*const *names;
 	bool			can_sleep;
+	bool			irq_not_threaded;
 	bool			exported;
 
 #ifdef CONFIG_GPIOLIB_IRQCHIP
-- 
1.9.1

[PATCH v5 4/4] gpio: add support for the Diolan DLN-2 USB GPIO driver

[Octavian Purdila]

From: Daniel Baluta <daniel.baluta-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

This patch adds GPIO and IRQ support for the Diolan DLN-2 GPIO module.

Information about the USB protocol interface can be found in the
Programmer's Reference Manual [1], see section 2.9 for the GPIO
module commands and responses.

[1] https://www.diolan.com/downloads/dln-api-manual.pdf

Signed-off-by: Daniel Baluta <daniel.baluta-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Octavian Purdila <octavian.purdila-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 drivers/gpio/Kconfig     |  12 +
 drivers/gpio/Makefile    |   1 +
 drivers/gpio/gpio-dln2.c | 554 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 567 insertions(+)
 create mode 100644 drivers/gpio/gpio-dln2.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 9de1515..44ec206 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -897,4 +897,16 @@ config GPIO_VIPERBOARD
           River Tech's viperboard.h for detailed meaning
           of the module parameters.
 
+config GPIO_DLN2
+	tristate "Diolan DLN2 GPIO support"
+	depends on MFD_DLN2
+	select GPIOLIB_IRQCHIP
+
+	help
+	  Select this option to enable GPIO driver for the Diolan DLN2
+	  board.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called gpio-dln2.
+
 endif
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 5d024e3..eaa97a0 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_GPIO_CRYSTAL_COVE)	+= gpio-crystalcove.o
 obj-$(CONFIG_GPIO_DA9052)	+= gpio-da9052.o
 obj-$(CONFIG_GPIO_DA9055)	+= gpio-da9055.o
 obj-$(CONFIG_GPIO_DAVINCI)	+= gpio-davinci.o
+obj-$(CONFIG_GPIO_DLN2)		+= gpio-dln2.o
 obj-$(CONFIG_GPIO_DWAPB)	+= gpio-dwapb.o
 obj-$(CONFIG_GPIO_EM)		+= gpio-em.o
 obj-$(CONFIG_GPIO_EP93XX)	+= gpio-ep93xx.o
diff --git a/drivers/gpio/gpio-dln2.c b/drivers/gpio/gpio-dln2.c
new file mode 100644
index 0000000..95d8ca3
--- /dev/null
+++ b/drivers/gpio/gpio-dln2.c
@@ -0,0 +1,554 @@
+/*
+ * Driver for the Diolan DLN-2 USB-GPIO adapter
+ *
+ * Copyright (c) 2014 Intel Corporation
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/irqdomain.h>
+#include <linux/irq.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/gpio.h>
+#include <linux/gpio/driver.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/dln2.h>
+
+#define DLN2_GPIO_ID			0x01
+
+#define DLN2_GPIO_GET_PORT_COUNT	DLN2_CMD(0x00, DLN2_GPIO_ID)
+#define DLN2_GPIO_GET_PIN_COUNT		DLN2_CMD(0x01, DLN2_GPIO_ID)
+#define DLN2_GPIO_SET_DEBOUNCE		DLN2_CMD(0x04, DLN2_GPIO_ID)
+#define DLN2_GPIO_GET_DEBOUNCE		DLN2_CMD(0x05, DLN2_GPIO_ID)
+#define DLN2_GPIO_PORT_GET_VAL		DLN2_CMD(0x06, DLN2_GPIO_ID)
+#define DLN2_GPIO_PIN_GET_VAL		DLN2_CMD(0x0B, DLN2_GPIO_ID)
+#define DLN2_GPIO_PIN_SET_OUT_VAL	DLN2_CMD(0x0C, DLN2_GPIO_ID)
+#define DLN2_GPIO_PIN_GET_OUT_VAL	DLN2_CMD(0x0D, DLN2_GPIO_ID)
+#define DLN2_GPIO_CONDITION_MET_EV	DLN2_CMD(0x0F, DLN2_GPIO_ID)
+#define DLN2_GPIO_PIN_ENABLE		DLN2_CMD(0x10, DLN2_GPIO_ID)
+#define DLN2_GPIO_PIN_DISABLE		DLN2_CMD(0x11, DLN2_GPIO_ID)
+#define DLN2_GPIO_PIN_SET_DIRECTION	DLN2_CMD(0x13, DLN2_GPIO_ID)
+#define DLN2_GPIO_PIN_GET_DIRECTION	DLN2_CMD(0x14, DLN2_GPIO_ID)
+#define DLN2_GPIO_PIN_SET_EVENT_CFG	DLN2_CMD(0x1E, DLN2_GPIO_ID)
+#define DLN2_GPIO_PIN_GET_EVENT_CFG	DLN2_CMD(0x1F, DLN2_GPIO_ID)
+
+#define DLN2_GPIO_EVENT_NONE		0
+#define DLN2_GPIO_EVENT_CHANGE		1
+#define DLN2_GPIO_EVENT_LVL_HIGH	2
+#define DLN2_GPIO_EVENT_LVL_LOW		3
+#define DLN2_GPIO_EVENT_CHANGE_RISING	0x11
+#define DLN2_GPIO_EVENT_CHANGE_FALLING  0x21
+#define DLN2_GPIO_EVENT_MASK		0x0F
+
+#define DLN2_GPIO_MAX_PINS 32
+
+struct dln2_irq_work {
+	struct work_struct work;
+	struct dln2_gpio *dln2;
+	int pin;
+	int type;
+};
+
+struct dln2_gpio {
+	struct platform_device *pdev;
+	struct gpio_chip gpio;
+
+	/*
+	 * Cache pin direction to save us one transfer, since the
+	 * hardware has separate commands to read the in and out
+	 * values. Bit set for out, bit clear for in.
+	 */
+	DECLARE_BITMAP(pin_dir, DLN2_GPIO_MAX_PINS);
+
+	DECLARE_BITMAP(irqs_masked, DLN2_GPIO_MAX_PINS);
+	DECLARE_BITMAP(irqs_enabled, DLN2_GPIO_MAX_PINS);
+	DECLARE_BITMAP(irqs_pending, DLN2_GPIO_MAX_PINS);
+	struct dln2_irq_work *irq_work;
+};
+
+struct dln2_gpio_pin {
+	__le16 pin;
+} __packed;
+
+struct dln2_gpio_pin_val {
+	__le16 pin;
+	u8 value;
+} __packed;
+
+static int dln2_gpio_get_pin_count(struct platform_device *pdev)
+{
+	int ret;
+	__le16 count;
+	int len = sizeof(count);
+
+	ret = dln2_transfer(pdev, DLN2_GPIO_GET_PIN_COUNT, NULL, 0, &count,
+			    &len);
+	if (ret < 0)
+		return ret;
+	if (len < sizeof(count))
+		return -EPROTO;
+
+	return le16_to_cpu(count);
+}
+
+static int dln2_gpio_pin_cmd(struct dln2_gpio *dln2, int cmd, unsigned pin)
+{
+	struct dln2_gpio_pin req = {
+		.pin = cpu_to_le16(pin),
+	};
+
+	return dln2_transfer(dln2->pdev, cmd, &req, sizeof(req), NULL, NULL);
+}
+
+static int dln2_gpio_pin_val(struct dln2_gpio *dln2, int cmd, unsigned int pin)
+{
+	int ret;
+	struct dln2_gpio_pin req = {
+		.pin = cpu_to_le16(pin),
+	};
+	struct dln2_gpio_pin_val rsp;
+	int len = sizeof(rsp);
+
+	ret = dln2_transfer(dln2->pdev, cmd, &req, sizeof(req), &rsp, &len);
+	if (ret < 0)
+		return ret;
+	if (len < sizeof(rsp) || req.pin != rsp.pin)
+		return -EPROTO;
+
+	return rsp.value;
+}
+
+static int dln2_gpio_pin_get_in_val(struct dln2_gpio *dln2, unsigned int pin)
+{
+	int ret;
+
+	ret = dln2_gpio_pin_val(dln2, DLN2_GPIO_PIN_GET_VAL, pin);
+	if (ret < 0)
+		return ret;
+	return !!ret;
+}
+
+static int dln2_gpio_pin_get_out_val(struct dln2_gpio *dln2, unsigned int pin)
+{
+	int ret;
+
+	ret = dln2_gpio_pin_val(dln2, DLN2_GPIO_PIN_GET_OUT_VAL, pin);
+	if (ret < 0)
+		return ret;
+	return !!ret;
+}
+
+static void dln2_gpio_pin_set_out_val(struct dln2_gpio *dln2,
+				      unsigned int pin, int value)
+{
+	struct dln2_gpio_pin_val req = {
+		.pin = cpu_to_le16(pin),
+		.value = cpu_to_le16(value),
+	};
+
+	dln2_transfer(dln2->pdev, DLN2_GPIO_PIN_SET_OUT_VAL, &req, sizeof(req),
+		      NULL, NULL);
+}
+
+#define DLN2_GPIO_DIRECTION_IN		0
+#define DLN2_GPIO_DIRECTION_OUT		1
+
+static int dln2_gpio_request(struct gpio_chip *chip, unsigned offset)
+{
+	struct dln2_gpio *dln2 = container_of(chip, struct dln2_gpio, gpio);
+	struct dln2_gpio_pin req = {
+		.pin = cpu_to_le16(offset),
+	};
+	struct dln2_gpio_pin_val rsp;
+	int len = sizeof(rsp);
+	int ret;
+
+	ret = dln2_gpio_pin_cmd(dln2, DLN2_GPIO_PIN_ENABLE, offset);
+	if (ret < 0)
+		return ret;
+
+	/* cache the pin direction */
+	ret = dln2_transfer(dln2->pdev, DLN2_GPIO_PIN_GET_DIRECTION,
+			    &req, sizeof(req), &rsp, &len);
+	if (ret < 0)
+		return ret;
+	if (len < sizeof(rsp) || req.pin != rsp.pin)
+		return -EPROTO;
+
+	switch (rsp.value) {
+	case DLN2_GPIO_DIRECTION_IN:
+		clear_bit(offset, dln2->pin_dir);
+		return 0;
+	case DLN2_GPIO_DIRECTION_OUT:
+		set_bit(offset, dln2->pin_dir);
+		return 0;
+	default:
+		return -EPROTO;
+	}
+}
+
+static void dln2_gpio_free(struct gpio_chip *chip, unsigned offset)
+{
+	struct dln2_gpio *dln2 = container_of(chip, struct dln2_gpio, gpio);
+
+	dln2_gpio_pin_cmd(dln2, DLN2_GPIO_PIN_DISABLE, offset);
+}
+
+static int dln2_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
+{
+	struct dln2_gpio *dln2 = container_of(chip, struct dln2_gpio, gpio);
+
+	if (test_bit(offset, dln2->pin_dir))
+		return GPIOF_DIR_OUT;
+
+	return GPIOF_DIR_IN;
+}
+
+static int dln2_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+	struct dln2_gpio *dln2 = container_of(chip, struct dln2_gpio, gpio);
+	int dir;
+
+	dir = dln2_gpio_get_direction(chip, offset);
+	if (dir < 0)
+		return dir;
+
+	if (dir == GPIOF_DIR_IN)
+		return dln2_gpio_pin_get_in_val(dln2, offset);
+
+	return dln2_gpio_pin_get_out_val(dln2, offset);
+}
+
+static void dln2_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+	struct dln2_gpio *dln2 = container_of(chip, struct dln2_gpio, gpio);
+
+	dln2_gpio_pin_set_out_val(dln2, offset, value);
+}
+
+static int dln2_gpio_set_direction(struct gpio_chip *chip, unsigned offset,
+				   unsigned dir)
+{
+	struct dln2_gpio *dln2 = container_of(chip, struct dln2_gpio, gpio);
+	struct dln2_gpio_pin_val req = {
+		.pin = cpu_to_le16(offset),
+		.value = cpu_to_le16(dir),
+	};
+	int ret;
+
+	ret = dln2_transfer(dln2->pdev, DLN2_GPIO_PIN_SET_DIRECTION,
+			    &req, sizeof(req), NULL, NULL);
+	if (ret < 0)
+		return ret;
+
+	if (dir == DLN2_GPIO_DIRECTION_OUT)
+		set_bit(offset, dln2->pin_dir);
+	else
+		clear_bit(offset, dln2->pin_dir);
+
+	return ret;
+}
+
+static int dln2_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
+{
+	return dln2_gpio_set_direction(chip, offset, DLN2_GPIO_DIRECTION_IN);
+}
+
+static int dln2_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
+				      int value)
+{
+	return dln2_gpio_set_direction(chip, offset, DLN2_GPIO_DIRECTION_OUT);
+}
+
+static int dln2_gpio_set_debounce(struct gpio_chip *chip, unsigned offset,
+				  unsigned debounce)
+{
+	struct dln2_gpio *dln2 = container_of(chip, struct dln2_gpio, gpio);
+	struct {
+		__le32 duration;
+	} __packed req = {
+		.duration = cpu_to_le32(debounce),
+	};
+
+	return dln2_transfer(dln2->pdev, DLN2_GPIO_SET_DEBOUNCE,
+			     &req, sizeof(req), NULL, NULL);
+}
+
+static int dln2_gpio_set_event_cfg(struct dln2_gpio *dln2, unsigned pin,
+				   unsigned type, unsigned period)
+{
+	struct {
+		__le16 pin;
+		u8 type;
+		__le16 period;
+	} __packed req = {
+		.pin = cpu_to_le16(pin),
+		.type = type,
+		.period = cpu_to_le16(period),
+	};
+
+	return dln2_transfer(dln2->pdev, DLN2_GPIO_PIN_SET_EVENT_CFG,
+			     &req, sizeof(req), NULL, NULL);
+}
+
+static void dln2_irq_work(struct work_struct *w)
+{
+	struct dln2_irq_work *iw = container_of(w, struct dln2_irq_work, work);
+	struct dln2_gpio *dln2 = iw->dln2;
+	u8 type = iw->type & DLN2_GPIO_EVENT_MASK;
+
+	if (test_bit(iw->pin, dln2->irqs_enabled))
+		dln2_gpio_set_event_cfg(dln2, iw->pin, type, 0);
+	else
+		dln2_gpio_set_event_cfg(dln2, iw->pin, DLN2_GPIO_EVENT_NONE, 0);
+}
+
+static void dln2_irq_enable(struct irq_data *irqd)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
+	struct dln2_gpio *dln2 = container_of(gc, struct dln2_gpio, gpio);
+	int pin = irqd_to_hwirq(irqd);
+
+	set_bit(pin, dln2->irqs_enabled);
+	schedule_work(&dln2->irq_work[pin].work);
+}
+
+static void dln2_irq_disable(struct irq_data *irqd)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
+	struct dln2_gpio *dln2 = container_of(gc, struct dln2_gpio, gpio);
+	int pin = irqd_to_hwirq(irqd);
+
+	clear_bit(pin, dln2->irqs_enabled);
+	schedule_work(&dln2->irq_work[pin].work);
+}
+
+static void dln2_irq_mask(struct irq_data *irqd)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
+	struct dln2_gpio *dln2 = container_of(gc, struct dln2_gpio, gpio);
+	int pin = irqd_to_hwirq(irqd);
+
+	set_bit(pin, dln2->irqs_masked);
+}
+
+static void dln2_irq_unmask(struct irq_data *irqd)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
+	struct dln2_gpio *dln2 = container_of(gc, struct dln2_gpio, gpio);
+	struct device *dev = dln2->gpio.dev;
+	int pin = irqd_to_hwirq(irqd);
+
+	if (test_and_clear_bit(pin, dln2->irqs_pending)) {
+		int irq;
+
+		irq = irq_find_mapping(dln2->gpio.irqdomain, pin);
+		if (!irq) {
+			dev_err(dev, "pin %d not mapped to IRQ\n", pin);
+			return;
+		}
+
+		generic_handle_irq(irq);
+	}
+}
+
+static int dln2_irq_set_type(struct irq_data *irqd, unsigned type)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
+	struct dln2_gpio *dln2 = container_of(gc, struct dln2_gpio, gpio);
+	int pin = irqd_to_hwirq(irqd);
+
+	switch (type) {
+	case IRQ_TYPE_LEVEL_HIGH:
+		dln2->irq_work[pin].type = DLN2_GPIO_EVENT_LVL_HIGH;
+		break;
+	case IRQ_TYPE_LEVEL_LOW:
+		dln2->irq_work[pin].type = DLN2_GPIO_EVENT_LVL_LOW;
+		break;
+	case IRQ_TYPE_EDGE_BOTH:
+		dln2->irq_work[pin].type = DLN2_GPIO_EVENT_CHANGE;
+		break;
+	case IRQ_TYPE_EDGE_RISING:
+		dln2->irq_work[pin].type = DLN2_GPIO_EVENT_CHANGE_RISING;
+		break;
+	case IRQ_TYPE_EDGE_FALLING:
+		dln2->irq_work[pin].type = DLN2_GPIO_EVENT_CHANGE_FALLING;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static struct irq_chip dln2_gpio_irqchip = {
+	.name = "dln2-irq",
+	.irq_enable = dln2_irq_enable,
+	.irq_disable = dln2_irq_disable,
+	.irq_mask = dln2_irq_mask,
+	.irq_unmask = dln2_irq_unmask,
+	.irq_set_type = dln2_irq_set_type,
+};
+
+static void dln2_gpio_event(struct platform_device *pdev, u16 echo,
+			    const void *data, int len)
+{
+	int pin, irq;
+	const struct {
+		__le16 count;
+		__u8 type;
+		__le16 pin;
+		__u8 value;
+	} __packed *event = data;
+	struct dln2_gpio *dln2 = platform_get_drvdata(pdev);
+
+	if (len < sizeof(*event)) {
+		dev_err(dln2->gpio.dev, "short event message\n");
+		return;
+	}
+
+	pin = le16_to_cpu(event->pin);
+	if (pin >= dln2->gpio.ngpio) {
+		dev_err(dln2->gpio.dev, "out of bounds pin %d\n", pin);
+		return;
+	}
+
+	irq = irq_find_mapping(dln2->gpio.irqdomain, pin);
+	if (!irq) {
+		dev_err(dln2->gpio.dev, "pin %d not mapped to IRQ\n", pin);
+		return;
+	}
+
+	if (!test_bit(pin, dln2->irqs_enabled))
+		return;
+	if (test_bit(pin, dln2->irqs_masked)) {
+		set_bit(pin, dln2->irqs_pending);
+		return;
+	}
+
+	switch (dln2->irq_work[pin].type) {
+	case DLN2_GPIO_EVENT_CHANGE_RISING:
+		if (event->value)
+			generic_handle_irq(irq);
+		break;
+	case DLN2_GPIO_EVENT_CHANGE_FALLING:
+		if (!event->value)
+			generic_handle_irq(irq);
+		break;
+	default:
+		generic_handle_irq(irq);
+	}
+}
+
+static int dln2_gpio_probe(struct platform_device *pdev)
+{
+	struct dln2_gpio *dln2;
+	struct device *dev = &pdev->dev;
+	int pins;
+	int i, ret;
+
+	pins = dln2_gpio_get_pin_count(pdev);
+	if (pins < 0) {
+		dev_err(dev, "failed to get pin count: %d\n", pins);
+		return pins;
+	}
+	if (pins > DLN2_GPIO_MAX_PINS) {
+		pins = DLN2_GPIO_MAX_PINS;
+		dev_warn(dev, "clamping pins to %d\n", DLN2_GPIO_MAX_PINS);
+	}
+
+	dln2 = devm_kzalloc(&pdev->dev, sizeof(*dln2), GFP_KERNEL);
+	if (!dln2)
+		return -ENOMEM;
+
+	dln2->irq_work = devm_kcalloc(&pdev->dev, pins,
+				      sizeof(struct dln2_irq_work), GFP_KERNEL);
+	if (!dln2->irq_work)
+		return -ENOMEM;
+	for (i = 0; i < pins; i++) {
+		INIT_WORK(&dln2->irq_work[i].work, dln2_irq_work);
+		dln2->irq_work[i].pin = i;
+		dln2->irq_work[i].dln2 = dln2;
+	}
+
+	dln2->pdev = pdev;
+
+	dln2->gpio.label = "dln2";
+	dln2->gpio.dev = dev;
+	dln2->gpio.owner = THIS_MODULE;
+	dln2->gpio.base = -1;
+	dln2->gpio.ngpio = pins;
+	dln2->gpio.exported = true;
+	dln2->gpio.can_sleep = true;
+	dln2->gpio.irq_not_threaded = true;
+	dln2->gpio.set = dln2_gpio_set;
+	dln2->gpio.get = dln2_gpio_get;
+	dln2->gpio.request = dln2_gpio_request;
+	dln2->gpio.free = dln2_gpio_free;
+	dln2->gpio.get_direction = dln2_gpio_get_direction;
+	dln2->gpio.direction_input = dln2_gpio_direction_input;
+	dln2->gpio.direction_output = dln2_gpio_direction_output;
+	dln2->gpio.set_debounce = dln2_gpio_set_debounce;
+
+	platform_set_drvdata(pdev, dln2);
+
+	ret = gpiochip_add(&dln2->gpio);
+	if (ret < 0) {
+		dev_err(dev, "failed to add gpio chip: %d\n", ret);
+		goto out;
+	}
+
+	ret = gpiochip_irqchip_add(&dln2->gpio, &dln2_gpio_irqchip, 0,
+				   handle_simple_irq, IRQ_TYPE_NONE);
+	if (ret < 0) {
+		dev_err(dev, "failed to add irq chip: %d\n", ret);
+		goto out_gpiochip_remove;
+	}
+
+	ret = dln2_register_event_cb(pdev, DLN2_GPIO_CONDITION_MET_EV,
+				     dln2_gpio_event);
+	if (ret) {
+		dev_err(dev, "failed to register event cb: %d\n", ret);
+		goto out_gpiochip_remove;
+	}
+
+	return 0;
+
+out_gpiochip_remove:
+	gpiochip_remove(&dln2->gpio);
+out:
+	return ret;
+}
+
+static int dln2_gpio_remove(struct platform_device *pdev)
+{
+	struct dln2_gpio *dln2 = platform_get_drvdata(pdev);
+	int i;
+
+	dln2_unregister_event_cb(pdev, DLN2_GPIO_CONDITION_MET_EV);
+	for (i = 0; i < dln2->gpio.ngpio; i++)
+		flush_work(&dln2->irq_work[i].work);
+	gpiochip_remove(&dln2->gpio);
+
+	return 0;
+}
+
+static struct platform_driver dln2_gpio_driver = {
+	.driver.name	= "dln2-gpio",
+	.driver.owner	= THIS_MODULE,
+	.probe		= dln2_gpio_probe,
+	.remove		= dln2_gpio_remove,
+};
+
+module_platform_driver(dln2_gpio_driver);
+
+MODULE_AUTHOR("Daniel Baluta <daniel.baluta-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org");
+MODULE_DESCRIPTION("Driver for the Diolan DLN2 GPIO interface");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:dln2-gpio");
-- 
1.9.1

[PATCH v5 4/4] gpio: add support for the Diolan DLN-2 USB GPIO driver

[Octavian Purdila]

From: Daniel Baluta <daniel.baluta@intel.com>

This patch adds GPIO and IRQ support for the Diolan DLN-2 GPIO module.

Information about the USB protocol interface can be found in the
Programmer's Reference Manual [1], see section 2.9 for the GPIO
module commands and responses.

[1] https://www.diolan.com/downloads/dln-api-manual.pdf

Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
---
 drivers/gpio/Kconfig     |  12 +
 drivers/gpio/Makefile    |   1 +
 drivers/gpio/gpio-dln2.c | 554 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 567 insertions(+)
 create mode 100644 drivers/gpio/gpio-dln2.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 9de1515..44ec206 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -897,4 +897,16 @@ config GPIO_VIPERBOARD
           River Tech's viperboard.h for detailed meaning
           of the module parameters.
 
+config GPIO_DLN2
+	tristate "Diolan DLN2 GPIO support"
+	depends on MFD_DLN2
+	select GPIOLIB_IRQCHIP
+
+	help
+	  Select this option to enable GPIO driver for the Diolan DLN2
+	  board.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called gpio-dln2.
+
 endif
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 5d024e3..eaa97a0 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_GPIO_CRYSTAL_COVE)	+= gpio-crystalcove.o
 obj-$(CONFIG_GPIO_DA9052)	+= gpio-da9052.o
 obj-$(CONFIG_GPIO_DA9055)	+= gpio-da9055.o
 obj-$(CONFIG_GPIO_DAVINCI)	+= gpio-davinci.o
+obj-$(CONFIG_GPIO_DLN2)		+= gpio-dln2.o
 obj-$(CONFIG_GPIO_DWAPB)	+= gpio-dwapb.o
 obj-$(CONFIG_GPIO_EM)		+= gpio-em.o
 obj-$(CONFIG_GPIO_EP93XX)	+= gpio-ep93xx.o
diff --git a/drivers/gpio/gpio-dln2.c b/drivers/gpio/gpio-dln2.c
new file mode 100644
index 0000000..95d8ca3
--- /dev/null
+++ b/drivers/gpio/gpio-dln2.c
@@ -0,0 +1,554 @@
+/*
+ * Driver for the Diolan DLN-2 USB-GPIO adapter
+ *
+ * Copyright (c) 2014 Intel Corporation
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/irqdomain.h>
+#include <linux/irq.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/gpio.h>
+#include <linux/gpio/driver.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/dln2.h>
+
+#define DLN2_GPIO_ID			0x01
+
+#define DLN2_GPIO_GET_PORT_COUNT	DLN2_CMD(0x00, DLN2_GPIO_ID)
+#define DLN2_GPIO_GET_PIN_COUNT		DLN2_CMD(0x01, DLN2_GPIO_ID)
+#define DLN2_GPIO_SET_DEBOUNCE		DLN2_CMD(0x04, DLN2_GPIO_ID)
+#define DLN2_GPIO_GET_DEBOUNCE		DLN2_CMD(0x05, DLN2_GPIO_ID)
+#define DLN2_GPIO_PORT_GET_VAL		DLN2_CMD(0x06, DLN2_GPIO_ID)
+#define DLN2_GPIO_PIN_GET_VAL		DLN2_CMD(0x0B, DLN2_GPIO_ID)
+#define DLN2_GPIO_PIN_SET_OUT_VAL	DLN2_CMD(0x0C, DLN2_GPIO_ID)
+#define DLN2_GPIO_PIN_GET_OUT_VAL	DLN2_CMD(0x0D, DLN2_GPIO_ID)
+#define DLN2_GPIO_CONDITION_MET_EV	DLN2_CMD(0x0F, DLN2_GPIO_ID)
+#define DLN2_GPIO_PIN_ENABLE		DLN2_CMD(0x10, DLN2_GPIO_ID)
+#define DLN2_GPIO_PIN_DISABLE		DLN2_CMD(0x11, DLN2_GPIO_ID)
+#define DLN2_GPIO_PIN_SET_DIRECTION	DLN2_CMD(0x13, DLN2_GPIO_ID)
+#define DLN2_GPIO_PIN_GET_DIRECTION	DLN2_CMD(0x14, DLN2_GPIO_ID)
+#define DLN2_GPIO_PIN_SET_EVENT_CFG	DLN2_CMD(0x1E, DLN2_GPIO_ID)
+#define DLN2_GPIO_PIN_GET_EVENT_CFG	DLN2_CMD(0x1F, DLN2_GPIO_ID)
+
+#define DLN2_GPIO_EVENT_NONE		0
+#define DLN2_GPIO_EVENT_CHANGE		1
+#define DLN2_GPIO_EVENT_LVL_HIGH	2
+#define DLN2_GPIO_EVENT_LVL_LOW		3
+#define DLN2_GPIO_EVENT_CHANGE_RISING	0x11
+#define DLN2_GPIO_EVENT_CHANGE_FALLING  0x21
+#define DLN2_GPIO_EVENT_MASK		0x0F
+
+#define DLN2_GPIO_MAX_PINS 32
+
+struct dln2_irq_work {
+	struct work_struct work;
+	struct dln2_gpio *dln2;
+	int pin;
+	int type;
+};
+
+struct dln2_gpio {
+	struct platform_device *pdev;
+	struct gpio_chip gpio;
+
+	/*
+	 * Cache pin direction to save us one transfer, since the
+	 * hardware has separate commands to read the in and out
+	 * values. Bit set for out, bit clear for in.
+	 */
+	DECLARE_BITMAP(pin_dir, DLN2_GPIO_MAX_PINS);
+
+	DECLARE_BITMAP(irqs_masked, DLN2_GPIO_MAX_PINS);
+	DECLARE_BITMAP(irqs_enabled, DLN2_GPIO_MAX_PINS);
+	DECLARE_BITMAP(irqs_pending, DLN2_GPIO_MAX_PINS);
+	struct dln2_irq_work *irq_work;
+};
+
+struct dln2_gpio_pin {
+	__le16 pin;
+} __packed;
+
+struct dln2_gpio_pin_val {
+	__le16 pin;
+	u8 value;
+} __packed;
+
+static int dln2_gpio_get_pin_count(struct platform_device *pdev)
+{
+	int ret;
+	__le16 count;
+	int len = sizeof(count);
+
+	ret = dln2_transfer(pdev, DLN2_GPIO_GET_PIN_COUNT, NULL, 0, &count,
+			    &len);
+	if (ret < 0)
+		return ret;
+	if (len < sizeof(count))
+		return -EPROTO;
+
+	return le16_to_cpu(count);
+}
+
+static int dln2_gpio_pin_cmd(struct dln2_gpio *dln2, int cmd, unsigned pin)
+{
+	struct dln2_gpio_pin req = {
+		.pin = cpu_to_le16(pin),
+	};
+
+	return dln2_transfer(dln2->pdev, cmd, &req, sizeof(req), NULL, NULL);
+}
+
+static int dln2_gpio_pin_val(struct dln2_gpio *dln2, int cmd, unsigned int pin)
+{
+	int ret;
+	struct dln2_gpio_pin req = {
+		.pin = cpu_to_le16(pin),
+	};
+	struct dln2_gpio_pin_val rsp;
+	int len = sizeof(rsp);
+
+	ret = dln2_transfer(dln2->pdev, cmd, &req, sizeof(req), &rsp, &len);
+	if (ret < 0)
+		return ret;
+	if (len < sizeof(rsp) || req.pin != rsp.pin)
+		return -EPROTO;
+
+	return rsp.value;
+}
+
+static int dln2_gpio_pin_get_in_val(struct dln2_gpio *dln2, unsigned int pin)
+{
+	int ret;
+
+	ret = dln2_gpio_pin_val(dln2, DLN2_GPIO_PIN_GET_VAL, pin);
+	if (ret < 0)
+		return ret;
+	return !!ret;
+}
+
+static int dln2_gpio_pin_get_out_val(struct dln2_gpio *dln2, unsigned int pin)
+{
+	int ret;
+
+	ret = dln2_gpio_pin_val(dln2, DLN2_GPIO_PIN_GET_OUT_VAL, pin);
+	if (ret < 0)
+		return ret;
+	return !!ret;
+}
+
+static void dln2_gpio_pin_set_out_val(struct dln2_gpio *dln2,
+				      unsigned int pin, int value)
+{
+	struct dln2_gpio_pin_val req = {
+		.pin = cpu_to_le16(pin),
+		.value = cpu_to_le16(value),
+	};
+
+	dln2_transfer(dln2->pdev, DLN2_GPIO_PIN_SET_OUT_VAL, &req, sizeof(req),
+		      NULL, NULL);
+}
+
+#define DLN2_GPIO_DIRECTION_IN		0
+#define DLN2_GPIO_DIRECTION_OUT		1
+
+static int dln2_gpio_request(struct gpio_chip *chip, unsigned offset)
+{
+	struct dln2_gpio *dln2 = container_of(chip, struct dln2_gpio, gpio);
+	struct dln2_gpio_pin req = {
+		.pin = cpu_to_le16(offset),
+	};
+	struct dln2_gpio_pin_val rsp;
+	int len = sizeof(rsp);
+	int ret;
+
+	ret = dln2_gpio_pin_cmd(dln2, DLN2_GPIO_PIN_ENABLE, offset);
+	if (ret < 0)
+		return ret;
+
+	/* cache the pin direction */
+	ret = dln2_transfer(dln2->pdev, DLN2_GPIO_PIN_GET_DIRECTION,
+			    &req, sizeof(req), &rsp, &len);
+	if (ret < 0)
+		return ret;
+	if (len < sizeof(rsp) || req.pin != rsp.pin)
+		return -EPROTO;
+
+	switch (rsp.value) {
+	case DLN2_GPIO_DIRECTION_IN:
+		clear_bit(offset, dln2->pin_dir);
+		return 0;
+	case DLN2_GPIO_DIRECTION_OUT:
+		set_bit(offset, dln2->pin_dir);
+		return 0;
+	default:
+		return -EPROTO;
+	}
+}
+
+static void dln2_gpio_free(struct gpio_chip *chip, unsigned offset)
+{
+	struct dln2_gpio *dln2 = container_of(chip, struct dln2_gpio, gpio);
+
+	dln2_gpio_pin_cmd(dln2, DLN2_GPIO_PIN_DISABLE, offset);
+}
+
+static int dln2_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
+{
+	struct dln2_gpio *dln2 = container_of(chip, struct dln2_gpio, gpio);
+
+	if (test_bit(offset, dln2->pin_dir))
+		return GPIOF_DIR_OUT;
+
+	return GPIOF_DIR_IN;
+}
+
+static int dln2_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+	struct dln2_gpio *dln2 = container_of(chip, struct dln2_gpio, gpio);
+	int dir;
+
+	dir = dln2_gpio_get_direction(chip, offset);
+	if (dir < 0)
+		return dir;
+
+	if (dir == GPIOF_DIR_IN)
+		return dln2_gpio_pin_get_in_val(dln2, offset);
+
+	return dln2_gpio_pin_get_out_val(dln2, offset);
+}
+
+static void dln2_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+	struct dln2_gpio *dln2 = container_of(chip, struct dln2_gpio, gpio);
+
+	dln2_gpio_pin_set_out_val(dln2, offset, value);
+}
+
+static int dln2_gpio_set_direction(struct gpio_chip *chip, unsigned offset,
+				   unsigned dir)
+{
+	struct dln2_gpio *dln2 = container_of(chip, struct dln2_gpio, gpio);
+	struct dln2_gpio_pin_val req = {
+		.pin = cpu_to_le16(offset),
+		.value = cpu_to_le16(dir),
+	};
+	int ret;
+
+	ret = dln2_transfer(dln2->pdev, DLN2_GPIO_PIN_SET_DIRECTION,
+			    &req, sizeof(req), NULL, NULL);
+	if (ret < 0)
+		return ret;
+
+	if (dir == DLN2_GPIO_DIRECTION_OUT)
+		set_bit(offset, dln2->pin_dir);
+	else
+		clear_bit(offset, dln2->pin_dir);
+
+	return ret;
+}
+
+static int dln2_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
+{
+	return dln2_gpio_set_direction(chip, offset, DLN2_GPIO_DIRECTION_IN);
+}
+
+static int dln2_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
+				      int value)
+{
+	return dln2_gpio_set_direction(chip, offset, DLN2_GPIO_DIRECTION_OUT);
+}
+
+static int dln2_gpio_set_debounce(struct gpio_chip *chip, unsigned offset,
+				  unsigned debounce)
+{
+	struct dln2_gpio *dln2 = container_of(chip, struct dln2_gpio, gpio);
+	struct {
+		__le32 duration;
+	} __packed req = {
+		.duration = cpu_to_le32(debounce),
+	};
+
+	return dln2_transfer(dln2->pdev, DLN2_GPIO_SET_DEBOUNCE,
+			     &req, sizeof(req), NULL, NULL);
+}
+
+static int dln2_gpio_set_event_cfg(struct dln2_gpio *dln2, unsigned pin,
+				   unsigned type, unsigned period)
+{
+	struct {
+		__le16 pin;
+		u8 type;
+		__le16 period;
+	} __packed req = {
+		.pin = cpu_to_le16(pin),
+		.type = type,
+		.period = cpu_to_le16(period),
+	};
+
+	return dln2_transfer(dln2->pdev, DLN2_GPIO_PIN_SET_EVENT_CFG,
+			     &req, sizeof(req), NULL, NULL);
+}
+
+static void dln2_irq_work(struct work_struct *w)
+{
+	struct dln2_irq_work *iw = container_of(w, struct dln2_irq_work, work);
+	struct dln2_gpio *dln2 = iw->dln2;
+	u8 type = iw->type & DLN2_GPIO_EVENT_MASK;
+
+	if (test_bit(iw->pin, dln2->irqs_enabled))
+		dln2_gpio_set_event_cfg(dln2, iw->pin, type, 0);
+	else
+		dln2_gpio_set_event_cfg(dln2, iw->pin, DLN2_GPIO_EVENT_NONE, 0);
+}
+
+static void dln2_irq_enable(struct irq_data *irqd)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
+	struct dln2_gpio *dln2 = container_of(gc, struct dln2_gpio, gpio);
+	int pin = irqd_to_hwirq(irqd);
+
+	set_bit(pin, dln2->irqs_enabled);
+	schedule_work(&dln2->irq_work[pin].work);
+}
+
+static void dln2_irq_disable(struct irq_data *irqd)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
+	struct dln2_gpio *dln2 = container_of(gc, struct dln2_gpio, gpio);
+	int pin = irqd_to_hwirq(irqd);
+
+	clear_bit(pin, dln2->irqs_enabled);
+	schedule_work(&dln2->irq_work[pin].work);
+}
+
+static void dln2_irq_mask(struct irq_data *irqd)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
+	struct dln2_gpio *dln2 = container_of(gc, struct dln2_gpio, gpio);
+	int pin = irqd_to_hwirq(irqd);
+
+	set_bit(pin, dln2->irqs_masked);
+}
+
+static void dln2_irq_unmask(struct irq_data *irqd)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
+	struct dln2_gpio *dln2 = container_of(gc, struct dln2_gpio, gpio);
+	struct device *dev = dln2->gpio.dev;
+	int pin = irqd_to_hwirq(irqd);
+
+	if (test_and_clear_bit(pin, dln2->irqs_pending)) {
+		int irq;
+
+		irq = irq_find_mapping(dln2->gpio.irqdomain, pin);
+		if (!irq) {
+			dev_err(dev, "pin %d not mapped to IRQ\n", pin);
+			return;
+		}
+
+		generic_handle_irq(irq);
+	}
+}
+
+static int dln2_irq_set_type(struct irq_data *irqd, unsigned type)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
+	struct dln2_gpio *dln2 = container_of(gc, struct dln2_gpio, gpio);
+	int pin = irqd_to_hwirq(irqd);
+
+	switch (type) {
+	case IRQ_TYPE_LEVEL_HIGH:
+		dln2->irq_work[pin].type = DLN2_GPIO_EVENT_LVL_HIGH;
+		break;
+	case IRQ_TYPE_LEVEL_LOW:
+		dln2->irq_work[pin].type = DLN2_GPIO_EVENT_LVL_LOW;
+		break;
+	case IRQ_TYPE_EDGE_BOTH:
+		dln2->irq_work[pin].type = DLN2_GPIO_EVENT_CHANGE;
+		break;
+	case IRQ_TYPE_EDGE_RISING:
+		dln2->irq_work[pin].type = DLN2_GPIO_EVENT_CHANGE_RISING;
+		break;
+	case IRQ_TYPE_EDGE_FALLING:
+		dln2->irq_work[pin].type = DLN2_GPIO_EVENT_CHANGE_FALLING;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static struct irq_chip dln2_gpio_irqchip = {
+	.name = "dln2-irq",
+	.irq_enable = dln2_irq_enable,
+	.irq_disable = dln2_irq_disable,
+	.irq_mask = dln2_irq_mask,
+	.irq_unmask = dln2_irq_unmask,
+	.irq_set_type = dln2_irq_set_type,
+};
+
+static void dln2_gpio_event(struct platform_device *pdev, u16 echo,
+			    const void *data, int len)
+{
+	int pin, irq;
+	const struct {
+		__le16 count;
+		__u8 type;
+		__le16 pin;
+		__u8 value;
+	} __packed *event = data;
+	struct dln2_gpio *dln2 = platform_get_drvdata(pdev);
+
+	if (len < sizeof(*event)) {
+		dev_err(dln2->gpio.dev, "short event message\n");
+		return;
+	}
+
+	pin = le16_to_cpu(event->pin);
+	if (pin >= dln2->gpio.ngpio) {
+		dev_err(dln2->gpio.dev, "out of bounds pin %d\n", pin);
+		return;
+	}
+
+	irq = irq_find_mapping(dln2->gpio.irqdomain, pin);
+	if (!irq) {
+		dev_err(dln2->gpio.dev, "pin %d not mapped to IRQ\n", pin);
+		return;
+	}
+
+	if (!test_bit(pin, dln2->irqs_enabled))
+		return;
+	if (test_bit(pin, dln2->irqs_masked)) {
+		set_bit(pin, dln2->irqs_pending);
+		return;
+	}
+
+	switch (dln2->irq_work[pin].type) {
+	case DLN2_GPIO_EVENT_CHANGE_RISING:
+		if (event->value)
+			generic_handle_irq(irq);
+		break;
+	case DLN2_GPIO_EVENT_CHANGE_FALLING:
+		if (!event->value)
+			generic_handle_irq(irq);
+		break;
+	default:
+		generic_handle_irq(irq);
+	}
+}
+
+static int dln2_gpio_probe(struct platform_device *pdev)
+{
+	struct dln2_gpio *dln2;
+	struct device *dev = &pdev->dev;
+	int pins;
+	int i, ret;
+
+	pins = dln2_gpio_get_pin_count(pdev);
+	if (pins < 0) {
+		dev_err(dev, "failed to get pin count: %d\n", pins);
+		return pins;
+	}
+	if (pins > DLN2_GPIO_MAX_PINS) {
+		pins = DLN2_GPIO_MAX_PINS;
+		dev_warn(dev, "clamping pins to %d\n", DLN2_GPIO_MAX_PINS);
+	}
+
+	dln2 = devm_kzalloc(&pdev->dev, sizeof(*dln2), GFP_KERNEL);
+	if (!dln2)
+		return -ENOMEM;
+
+	dln2->irq_work = devm_kcalloc(&pdev->dev, pins,
+				      sizeof(struct dln2_irq_work), GFP_KERNEL);
+	if (!dln2->irq_work)
+		return -ENOMEM;
+	for (i = 0; i < pins; i++) {
+		INIT_WORK(&dln2->irq_work[i].work, dln2_irq_work);
+		dln2->irq_work[i].pin = i;
+		dln2->irq_work[i].dln2 = dln2;
+	}
+
+	dln2->pdev = pdev;
+
+	dln2->gpio.label = "dln2";
+	dln2->gpio.dev = dev;
+	dln2->gpio.owner = THIS_MODULE;
+	dln2->gpio.base = -1;
+	dln2->gpio.ngpio = pins;
+	dln2->gpio.exported = true;
+	dln2->gpio.can_sleep = true;
+	dln2->gpio.irq_not_threaded = true;
+	dln2->gpio.set = dln2_gpio_set;
+	dln2->gpio.get = dln2_gpio_get;
+	dln2->gpio.request = dln2_gpio_request;
+	dln2->gpio.free = dln2_gpio_free;
+	dln2->gpio.get_direction = dln2_gpio_get_direction;
+	dln2->gpio.direction_input = dln2_gpio_direction_input;
+	dln2->gpio.direction_output = dln2_gpio_direction_output;
+	dln2->gpio.set_debounce = dln2_gpio_set_debounce;
+
+	platform_set_drvdata(pdev, dln2);
+
+	ret = gpiochip_add(&dln2->gpio);
+	if (ret < 0) {
+		dev_err(dev, "failed to add gpio chip: %d\n", ret);
+		goto out;
+	}
+
+	ret = gpiochip_irqchip_add(&dln2->gpio, &dln2_gpio_irqchip, 0,
+				   handle_simple_irq, IRQ_TYPE_NONE);
+	if (ret < 0) {
+		dev_err(dev, "failed to add irq chip: %d\n", ret);
+		goto out_gpiochip_remove;
+	}
+
+	ret = dln2_register_event_cb(pdev, DLN2_GPIO_CONDITION_MET_EV,
+				     dln2_gpio_event);
+	if (ret) {
+		dev_err(dev, "failed to register event cb: %d\n", ret);
+		goto out_gpiochip_remove;
+	}
+
+	return 0;
+
+out_gpiochip_remove:
+	gpiochip_remove(&dln2->gpio);
+out:
+	return ret;
+}
+
+static int dln2_gpio_remove(struct platform_device *pdev)
+{
+	struct dln2_gpio *dln2 = platform_get_drvdata(pdev);
+	int i;
+
+	dln2_unregister_event_cb(pdev, DLN2_GPIO_CONDITION_MET_EV);
+	for (i = 0; i < dln2->gpio.ngpio; i++)
+		flush_work(&dln2->irq_work[i].work);
+	gpiochip_remove(&dln2->gpio);
+
+	return 0;
+}
+
+static struct platform_driver dln2_gpio_driver = {
+	.driver.name	= "dln2-gpio",
+	.driver.owner	= THIS_MODULE,
+	.probe		= dln2_gpio_probe,
+	.remove		= dln2_gpio_remove,
+};
+
+module_platform_driver(dln2_gpio_driver);
+
+MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com");
+MODULE_DESCRIPTION("Driver for the Diolan DLN2 GPIO interface");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:dln2-gpio");
-- 
1.9.1

Re: [PATCH v5 4/4] gpio: add support for the Diolan DLN-2 USB GPIO driver

[Arnd Bergmann]

On Friday 19 September 2014, Octavian Purdila wrote:
> +struct dln2_gpio_pin {
> +	__le16 pin;
> +} __packed;

This does not need to be marked packed, since it is never embedded in another
structure.

> +struct dln2_gpio_pin_val {
> +	__le16 pin;
> +	u8 value;
> +} __packed;

It's enough here to mark just the 'pin' member as packed.

> +static int dln2_gpio_get_pin_count(struct platform_device *pdev)
> +{
> +	int ret;
> +	__le16 count;
> +	int len = sizeof(count);
> +
> +	ret = dln2_transfer(pdev, DLN2_GPIO_GET_PIN_COUNT, NULL, 0, &count,
> +			    &len);

You must not do a USB transaction on stack memory.

> +static int dln2_gpio_pin_cmd(struct dln2_gpio *dln2, int cmd, unsigned pin)
> +{
> +	struct dln2_gpio_pin req = {
> +		.pin = cpu_to_le16(pin),
> +	};
> +
> +	return dln2_transfer(dln2->pdev, cmd, &req, sizeof(req), NULL, NULL);
> +}

Same here

> +static int dln2_gpio_pin_val(struct dln2_gpio *dln2, int cmd, unsigned int pin)
> +{
> +	int ret;
> +	struct dln2_gpio_pin req = {
> +		.pin = cpu_to_le16(pin),
> +	};
> +	struct dln2_gpio_pin_val rsp;

And here.

> +static int dln2_gpio_set_debounce(struct gpio_chip *chip, unsigned offset,
> +				  unsigned debounce)
> +{
> +	struct dln2_gpio *dln2 = container_of(chip, struct dln2_gpio, gpio);
> +	struct {
> +		__le32 duration;
> +	} __packed req = {
> +		.duration = cpu_to_le32(debounce),
> +	};
> +
> +	return dln2_transfer(dln2->pdev, DLN2_GPIO_SET_DEBOUNCE,
> +			     &req, sizeof(req), NULL, NULL);
> +}

Here you also have a strange __packed attribute that makes no sense
for a local variable, in addition to the stack problem.

I think the only correct way to handle these is to add a dynamic
allocation of an entire page for the DMA, which can probably be
part of the dln2_transfer function so you don't have to do it
in each caller.

	Arnd

Re: [PATCH v5 4/4] gpio: add support for the Diolan DLN-2 USB GPIO driver

[Octavian Purdila]

On Sat, Sep 20, 2014 at 5:48 AM, Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org> wrote:
> On Friday 19 September 2014, Octavian Purdila wrote:
>> +struct dln2_gpio_pin {
>> +     __le16 pin;
>> +} __packed;
>
> This does not need to be marked packed, since it is never embedded in another
> structure.
>

Will do.

>> +struct dln2_gpio_pin_val {
>> +     __le16 pin;
>> +     u8 value;
>> +} __packed;
>
> It's enough here to mark just the 'pin' member as packed.
>

OK.

>> +static int dln2_gpio_get_pin_count(struct platform_device *pdev)
>> +{
>> +     int ret;
>> +     __le16 count;
>> +     int len = sizeof(count);
>> +
>> +     ret = dln2_transfer(pdev, DLN2_GPIO_GET_PIN_COUNT, NULL, 0, &count,
>> +                         &len);
>
> You must not do a USB transaction on stack memory.
>

dln2_transfer allocate a new buffer (in dln2_prep_buf(), with
kmalloc()) and does the USB transfer with that buffer.
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Re: [PATCH v5 4/4] gpio: add support for the Diolan DLN-2 USB GPIO driver

[Octavian Purdila]

On Sat, Sep 20, 2014 at 5:48 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Friday 19 September 2014, Octavian Purdila wrote:
>> +struct dln2_gpio_pin {
>> +     __le16 pin;
>> +} __packed;
>
> This does not need to be marked packed, since it is never embedded in another
> structure.
>

Will do.

>> +struct dln2_gpio_pin_val {
>> +     __le16 pin;
>> +     u8 value;
>> +} __packed;
>
> It's enough here to mark just the 'pin' member as packed.
>

OK.

>> +static int dln2_gpio_get_pin_count(struct platform_device *pdev)
>> +{
>> +     int ret;
>> +     __le16 count;
>> +     int len = sizeof(count);
>> +
>> +     ret = dln2_transfer(pdev, DLN2_GPIO_GET_PIN_COUNT, NULL, 0, &count,
>> +                         &len);
>
> You must not do a USB transaction on stack memory.
>

dln2_transfer allocate a new buffer (in dln2_prep_buf(), with
kmalloc()) and does the USB transfer with that buffer.

Re: [PATCH v5 3/4] gpiolib: add irq_not_threaded flag to gpio_chip

[Linus Walleij]

On Fri, Sep 19, 2014 at 10:22 PM, Octavian Purdila
<octavian.purdila@intel.com> wrote:

> Some GPIO chips (e.g. the DLN2 USB adapter) have blocking get/set
> operation but do not need a threaded irq handler.
>
> Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>

Usually I don't apply patches adding interfaces with no users, but
this seems very useful, so patch applied. I guess your driver will
appear on v3.19+ so then you can rely on this having been merged
for v3.18.

Yours,
Linus Walleij

Re: [PATCH v5 1/4] mfd: add support for Diolan DLN-2 devices

[Johan Hovold]

On Fri, Sep 19, 2014 at 11:22:42PM +0300, Octavian Purdila wrote:
> This patch implements the USB part of the Diolan USB-I2C/SPI/GPIO
> Master Adapter DLN-2. Details about the device can be found here:
> 
> https://www.diolan.com/i2c/i2c_interface.html.
> 
> Information about the USB protocol can be found in the Programmer's
> Reference Manual [1], see section 1.7.
> 
> Because the hardware has a single transmit endpoint and a single
> receive endpoint the communication between the various DLN2 drivers
> and the hardware will be muxed/demuxed by this driver.
> 
> Each DLN2 module will be identified by the handle field within the DLN2
> message header. If a DLN2 module issues multiple commands in parallel
> they will be identified by the echo counter field in the message header.
> 
> The DLN2 modules can use the dln2_transfer() function to issue a
> command and wait for its response. They can also register a callback
> that is going to be called when a specific event id is generated by
> the device (e.g. GPIO interrupts). The device uses handle 0 for
> sending events.
> 
> [1] https://www.diolan.com/downloads/dln-api-manual.pdf
> 
> Signed-off-by: Octavian Purdila <octavian.purdila-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> ---
>  drivers/mfd/Kconfig      |   9 +
>  drivers/mfd/Makefile     |   1 +
>  drivers/mfd/dln2.c       | 758 +++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/dln2.h |  67 +++++
>  4 files changed, 835 insertions(+)
>  create mode 100644 drivers/mfd/dln2.c
>  create mode 100644 include/linux/mfd/dln2.h
> 
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index de5abf2..7bcf895 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -183,6 +183,15 @@ config MFD_DA9063
>  	  Additional drivers must be enabled in order to use the functionality
>  	  of the device.
>  
> +config MFD_DLN2
> +	tristate "Diolan DLN2 support"
> +	select MFD_CORE
> +	depends on USB
> +	help
> +	  This adds support for Diolan USB-I2C/SPI/GPIO Master Adapter DLN-2.
> +	  Additional drivers must be enabled in order to use the functionality
> +	  of the device.
> +
>  config MFD_MC13XXX
>  	tristate
>  	depends on (SPI_MASTER || I2C)
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index f001487..591988d 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -169,6 +169,7 @@ obj-$(CONFIG_MFD_AS3711)	+= as3711.o
>  obj-$(CONFIG_MFD_AS3722)	+= as3722.o
>  obj-$(CONFIG_MFD_STW481X)	+= stw481x.o
>  obj-$(CONFIG_MFD_IPAQ_MICRO)	+= ipaq-micro.o
> +obj-$(CONFIG_MFD_DLN2)		+= dln2.o
>  
>  intel-soc-pmic-objs		:= intel_soc_pmic_core.o intel_soc_pmic_crc.o
>  obj-$(CONFIG_INTEL_SOC_PMIC)	+= intel-soc-pmic.o
> diff --git a/drivers/mfd/dln2.c b/drivers/mfd/dln2.c
> new file mode 100644
> index 0000000..36c53cd
> --- /dev/null
> +++ b/drivers/mfd/dln2.c
> @@ -0,0 +1,758 @@
> +/*
> + * Driver for the Diolan DLN-2 USB adapter
> + *
> + * Copyright (c) 2014 Intel Corporation
> + *
> + * Derived from:
> + *  i2c-diolan-u2c.c
> + *  Copyright (c) 2010-2011 Ericsson AB
> + *
> + * 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.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/types.h>
> +#include <linux/slab.h>
> +#include <linux/usb.h>
> +#include <linux/i2c.h>
> +#include <linux/mutex.h>
> +#include <linux/platform_device.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/dln2.h>
> +#include <linux/rculist.h>
> +
> +struct dln2_header {
> +	__le16 size;
> +	__le16 id;
> +	__le16 echo;
> +	__le16 handle;
> +} __packed;
> +
> +struct dln2_response {
> +	struct dln2_header hdr;
> +	__le16 result;
> +} __packed;
> +
> +#define DLN2_GENERIC_MODULE_ID		0x00
> +#define DLN2_GENERIC_CMD(cmd)		DLN2_CMD(cmd, DLN2_GENERIC_MODULE_ID)
> +#define CMD_GET_DEVICE_VER		DLN2_GENERIC_CMD(0x30)
> +#define CMD_GET_DEVICE_SN		DLN2_GENERIC_CMD(0x31)
> +
> +#define DLN2_HW_ID			0x200
> +#define DLN2_USB_TIMEOUT		200	/* in ms */
> +#define DLN2_MAX_RX_SLOTS		16
> +#define DLN2_MAX_URBS			16
> +#define DLN2_RX_BUF_SIZE		512
> +
> +#define DLN2_HANDLE_EVENT		0
> +#define DLN2_HANDLE_CTRL		1
> +#define DLN2_HANDLE_GPIO		2
> +#define DLN2_HANDLE_I2C			3
> +#define DLN2_HANDLES			4

This should be an enum.

> +
> +
> +/*
> + * Receive context used between the receive demultiplexer and the
> + * transfer routine. While sending a request the transfer routine
> + * will look for a free receive context and use it to wait for a
> + * response and to receive the URB and thus the response data.
> + */
> +struct dln2_rx_context {
> +	/* completion used to wait a response */

wait for

> +	struct completion done;
> +
> +	/* if non-NULL the URB contains the response */
> +	struct urb *urb;
> +
> +	/* if true then this context is used to wait for a response */
> +	bool connected;

Now that you have a disconnected flag, perhaps you can rename this to
something more descriptive as, for example, in_use.

> +
> +	/* cancel waiting for a response, e.g. on USB disconnect */
> +	bool cancel;

You this new field now, but never use it.

> +};
> +
> +/*
> + * Receive contexts for a particular DLN2 module (i2c, gpio, etc.). We
> + * use the handle header field to indentify the module in

identify

> + * dln2_dev.mod_rx_slots and then the echo header field to index the
> + * slots field and find the receive context for a particular
> + * request.
> + */
> +struct dln2_mod_rx_slots {
> +	/* RX slots bitmap */
> +	unsigned long bmap;
> +
> +	/* used to wait for a free RX slot */
> +	wait_queue_head_t wq;
> +
> +	/* used to wait for an RX operation to complete */
> +	struct dln2_rx_context slots[DLN2_MAX_RX_SLOTS];
> +
> +	/* device has been disconnected */
> +	bool disconnected;

This belongs in the dln2_dev struct.

I think you're overcomplicating the disconnect handling by intertwining
it with your slots.

Add a lock, an active-transfer counter, a disconnected flag, and a wait
queue to struct dln2_dev.

More below.

> +
> +	/* avoid races between free_rx_slot, dln2_rx_transfer and dln2_stop */
> +	spinlock_t lock;
> +};
> +
> +struct dln2_dev {
> +	struct usb_device *usb_dev;
> +	struct usb_interface *interface;
> +	u8 ep_in;
> +	u8 ep_out;
> +
> +	struct urb *rx_urb[DLN2_MAX_URBS];
> +	void *rx_buf[DLN2_MAX_URBS];
> +
> +	struct dln2_mod_rx_slots mod_rx_slots[DLN2_HANDLES];
> +
> +	struct list_head rx_cb_list;
> +	spinlock_t rx_cb_lock;
> +};
> +
> +static bool find_free_slot(struct dln2_mod_rx_slots *rxs, int *slot)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&rxs->lock, flags);
> +
> +	if (rxs->disconnected) {

Check the global disconnected flag. Locking not needed.

> +		*slot = -ECONNRESET;

-ENODEV

> +		goto out;
> +	}
> +
> +	*slot = find_first_zero_bit(&rxs->bmap, DLN2_MAX_RX_SLOTS);
> +
> +	if (*slot < DLN2_MAX_RX_SLOTS) {
> +		struct dln2_rx_context *rxc = &rxs->slots[*slot];
> +
> +		set_bit(*slot, &rxs->bmap);
> +		rxc->connected = true;
> +	}
> +
> +out:
> +	spin_unlock_irqrestore(&rxs->lock, flags);
> +
> +	return *slot < DLN2_MAX_RX_SLOTS;
> +}
> +
> +static int alloc_rx_slot(struct dln2_mod_rx_slots *rxs)
> +{
> +	int ret;
> +	int slot;
> +
> +	/*
> +	 * No need to timeout here, the wait is bounded by the timeout
> +	 * in _dln2_transfer.
> +	 */
> +	ret = wait_event_interruptible(rxs->wq, find_free_slot(rxs, &slot));
> +	if (ret < 0)
> +		return ret;
> +
> +	return slot;
> +}
> +
> +static void free_rx_slot(struct dln2_dev *dln2, struct dln2_mod_rx_slots *rxs,
> +			 int slot)
> +{
> +	struct urb *urb = NULL;
> +	unsigned long flags;
> +	struct dln2_rx_context *rxc;
> +	struct device *dev = &dln2->interface->dev;
> +	int ret;
> +
> +	spin_lock_irqsave(&rxs->lock, flags);
> +
> +	clear_bit(slot, &rxs->bmap);
> +
> +	rxc = &rxs->slots[slot];
> +	rxc->connected = false;
> +	urb = rxc->urb;
> +	rxc->urb = NULL;
> +	reinit_completion(&rxc->done);
> +
> +	spin_unlock_irqrestore(&rxs->lock, flags);
> +
> +	if (urb) {
> +		ret = usb_submit_urb(urb, GFP_KERNEL);
> +		if (ret < 0)
> +			dev_err(dev, "failed to re-submit RX URB: %d\n", ret);
> +	}
> +
> +	wake_up_interruptible(&rxs->wq);
> +}

Could you move these three functions just above _dln2_transfer, which is
the only function they are used in?

> +
> +struct dln2_rx_cb_entry {
> +	struct list_head list;
> +	u16 id;
> +	struct platform_device *pdev;
> +	dln2_rx_cb_t callback;
> +};
> +
> +int dln2_register_event_cb(struct platform_device *pdev, u16 id,
> +			   dln2_rx_cb_t rx_cb)
> +{
> +	struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
> +	struct dln2_rx_cb_entry *i, *new;
> +	unsigned long flags;
> +	int ret = 0;
> +
> +	new = kmalloc(sizeof(*new), GFP_KERNEL);
> +	if (!new)
> +		return -ENOMEM;
> +
> +	new->id = id;
> +	new->callback = rx_cb;
> +	new->pdev = pdev;
> +
> +	spin_lock_irqsave(&dln2->rx_cb_lock, flags);
> +
> +	list_for_each_entry_rcu(i, &dln2->rx_cb_list, list) {

No need to use the _rcu version on the update side.

> +		if (i->id == id) {
> +			ret = -EBUSY;
> +			break;
> +		}
> +	}
> +
> +	if (!ret)
> +		list_add_rcu(&new->list, &dln2->rx_cb_list);
> +
> +	spin_unlock_irqrestore(&dln2->rx_cb_lock, flags);
> +
> +	if (ret)
> +		kfree(new);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(dln2_register_event_cb);
> +
> +void dln2_unregister_event_cb(struct platform_device *pdev, u16 id)
> +{
> +	struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
> +	struct dln2_rx_cb_entry *i;
> +	unsigned long flags;
> +	bool found = false;
> +
> +	spin_lock_irqsave(&dln2->rx_cb_lock, flags);
> +
> +	list_for_each_entry_rcu(i, &dln2->rx_cb_list, list) {

No need to use the _rcu version on the update side.

> +		if (i->id == id) {
> +			list_del_rcu(&i->list);
> +			found = true;
> +			break;
> +		}
> +	}
> +
> +	spin_unlock_irqrestore(&dln2->rx_cb_lock, flags);
> +
> +	if (found) {
> +		synchronize_rcu();
> +		kfree(i);
> +	}
> +}
> +EXPORT_SYMBOL(dln2_unregister_event_cb);
> +
> +static void dln2_rx_transfer(struct dln2_dev *dln2, struct urb *urb,
> +			     u16 handle, u16 rx_slot)
> +{
> +	struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
> +	struct dln2_rx_context *rxc;
> +	struct device *dev = &dln2->interface->dev;
> +	int err;
> +
> +	spin_lock(&rxs->lock);
> +	rxc = &rxs->slots[rx_slot];
> +	if (rxc->connected) {
> +		rxc->urb = urb;
> +		complete(&rxc->done);
> +	} else {
> +		dev_warn(dev, "dropping response %d/%d", handle, rx_slot);
> +		err = usb_submit_urb(urb, GFP_ATOMIC);
> +		if (err < 0)
> +			dev_err(dev, "failed to re-submit RX URB: %d\n", err);
> +	}
> +	spin_unlock(&rxs->lock);
> +}
> +
> +static void dln2_run_rx_callbacks(struct dln2_dev *dln2, u16 id, u16 echo,
> +				  void *data, int len)
> +{
> +	struct dln2_rx_cb_entry *i;
> +
> +	rcu_read_lock();
> +
> +	list_for_each_entry_rcu(i, &dln2->rx_cb_list, list)
> +		if (i->id == id)
> +			i->callback(i->pdev, echo, data, len);
> +
> +	rcu_read_unlock();
> +}
> +
> +static void dln2_rx(struct urb *urb)
> +{
> +	int err;
> +	struct dln2_dev *dln2 = urb->context;
> +	struct dln2_header *hdr = urb->transfer_buffer;
> +	struct device *dev = &dln2->interface->dev;
> +	u16 id, echo, handle, size;
> +	u8 *data;
> +	int len;
> +
> +	switch (urb->status) {
> +	case 0:
> +		/* success */
> +		break;
> +	case -ECONNRESET:
> +	case -ENOENT:
> +	case -ESHUTDOWN:
> +	case -EPIPE:
> +		/* this urb is terminated, clean up */
> +		dev_dbg(dev, "urb shutting down with status %d\n", urb->status);
> +		return;
> +	default:
> +		dev_dbg(dev, "nonzero urb status received %d\n", urb->status);
> +		goto out;
> +	}
> +
> +	if (urb->actual_length < sizeof(struct dln2_header)) {
> +		dev_err(dev, "short response: %d\n", urb->actual_length);
> +		goto out;
> +	}
> +
> +	handle = le16_to_cpu(hdr->handle);
> +	id = le16_to_cpu(hdr->id);
> +	echo = le16_to_cpu(hdr->echo);
> +	size = le16_to_cpu(hdr->size);
> +
> +	if (size != urb->actual_length) {
> +		dev_err(dev, "size mismatch: handle %x cmd %x echo %x size %d actual %d\n",
> +			handle, id, echo, size, urb->actual_length);
> +		goto out;
> +	}
> +
> +	if (handle >= DLN2_HANDLES) {
> +		dev_warn(dev, "RX: invalid handle %d\n", handle);
> +		goto out;
> +	}
> +
> +	data = urb->transfer_buffer + sizeof(struct dln2_header);
> +	len = urb->actual_length - sizeof(struct dln2_header);
> +
> +	if (handle == DLN2_HANDLE_EVENT) {
> +		dln2_run_rx_callbacks(dln2, id, echo, data, len);
> +		err = usb_submit_urb(urb, GFP_ATOMIC);
> +		if (err < 0)
> +			goto out_submit_failed;
> +	} else {
> +		dln2_rx_transfer(dln2, urb, handle, echo);
> +	}
> +
> +	return;
> +
> +out:
> +	err = usb_submit_urb(urb, GFP_ATOMIC);
> +out_submit_failed:
> +	if (err < 0)
> +		dev_err(dev, "failed to re-submit RX URB: %d\n", err);
> +}
> +
> +static void *dln2_prep_buf(u16 handle, u16 cmd, u16 echo, const void *obuf,
> +			   int *obuf_len, gfp_t gfp)
> +{
> +	int len;
> +	void *buf;
> +	struct dln2_header *hdr;
> +
> +	len = *obuf_len + sizeof(*hdr);
> +	buf = kmalloc(len, gfp);
> +	if (!buf)
> +		return NULL;
> +
> +	hdr = (struct dln2_header *)buf;
> +	hdr->id = cpu_to_le16(cmd);
> +	hdr->size = cpu_to_le16(len);
> +	hdr->echo = cpu_to_le16(echo);
> +	hdr->handle = cpu_to_le16(handle);
> +
> +	memcpy(buf + sizeof(*hdr), obuf, *obuf_len);
> +
> +	*obuf_len = len;
> +
> +	return buf;
> +}
> +
> +static int dln2_send_wait(struct dln2_dev *dln2, u16 handle, u16 cmd, u16 echo,
> +			  const void *obuf, int obuf_len)
> +{
> +	int ret = 0;
> +	int len = obuf_len;
> +	void *buf;
> +	int actual;
> +
> +	buf = dln2_prep_buf(handle, cmd, echo, obuf, &len, GFP_KERNEL);
> +	if (!buf)
> +		return -ENOMEM;
> +
> +	ret = usb_bulk_msg(dln2->usb_dev,
> +			   usb_sndbulkpipe(dln2->usb_dev, dln2->ep_out),
> +			   buf, len, &actual, DLN2_USB_TIMEOUT);
> +
> +	kfree(buf);
> +
> +	return ret;
> +}
> +
> +static int _dln2_transfer(struct dln2_dev *dln2, u16 handle, u16 cmd,
> +			  const void *obuf, unsigned obuf_len,
> +			  void *ibuf, unsigned *ibuf_len)
> +{
> +	int ret = 0;
> +	u16 result;
> +	int rx_slot;
> +	unsigned long flags;
> +	struct dln2_response *rsp;
> +	struct dln2_rx_context *rxc;
> +	struct device *dev;
> +	const int timeout = DLN2_USB_TIMEOUT * HZ / 1000;
> +	struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
> +

Check the disconnected flag before incrementing the transfer count
(while holding the device lock) here. Then decrement counter before
returning and wake up an waiters if disconnected below.

That is sufficient to implement wait-until-io-has-completed. Anything
else you do below and in the helper functions is only to speed things
up at disconnect (and can be done without locking the device).

> +	rx_slot = alloc_rx_slot(rxs);
> +	if (rx_slot < 0)
> +		return rx_slot;
> +
> +	dev = &dln2->interface->dev;
> +
> +	ret = dln2_send_wait(dln2, handle, cmd, rx_slot, obuf, obuf_len);
> +	if (ret < 0) {
> +		free_rx_slot(dln2, rxs, rx_slot);

goto out_free_rx_slot

> +		dev_err(dev, "USB write failed: %d", ret);
> +		return ret;
> +	}
> +
> +	rxc = &rxs->slots[rx_slot];
> +
> +	ret = wait_for_completion_interruptible_timeout(&rxc->done, timeout);
> +	if (ret <= 0) {
> +		if (!ret)
> +			ret = -ETIMEDOUT;
> +		goto out_free_rx_slot;
> +	}
> +
> +	spin_lock_irqsave(&rxs->lock, flags);
> +
> +	if (!rxc->urb) {

Just check the disconnected flag directly here. Locking not needed (see
below).

> +		ret = -ECONNRESET;

-ENODEV

> +		spin_unlock_irqrestore(&rxs->lock, flags);
> +		goto out_free_rx_slot;
> +	}
> +
> +	/* if we got here we know that the response header has been checked */
> +	rsp = rxc->urb->transfer_buffer;
> +
> +	spin_unlock_irqrestore(&rxs->lock, flags);
> +
> +	if (rsp->hdr.size < sizeof(*rsp)) {
> +		ret = -EPROTO;
> +		goto out_free_rx_slot;
> +	}
> +
> +	result = le16_to_cpu(rsp->result);
> +	if (result) {
> +		dev_dbg(dev, "%d received response with error %d\n",
> +			handle, result);
> +		ret = -EREMOTEIO;
> +		goto out_free_rx_slot;
> +	}
> +
> +	if (!ibuf) {
> +		ret = 0;
> +		goto out_free_rx_slot;
> +	}
> +
> +	if (*ibuf_len > rsp->hdr.size - sizeof(*rsp))
> +		*ibuf_len = rsp->hdr.size - sizeof(*rsp);
> +
> +	memcpy(ibuf, rsp + 1, *ibuf_len);
> +
> +out_free_rx_slot:
> +	free_rx_slot(dln2, rxs, rx_slot);
> +
> +	return ret;
> +}
> +
> +int dln2_transfer(struct platform_device *pdev, u16 cmd,
> +		  const void *obuf, unsigned obuf_len,
> +		  void *ibuf, unsigned *ibuf_len)
> +{
> +	struct dln2_platform_data *dln2_pdata;
> +	struct dln2_dev *dln2;
> +	u16 h;
> +
> +	dln2 = dev_get_drvdata(pdev->dev.parent);
> +	dln2_pdata = dev_get_platdata(&pdev->dev);
> +	h = dln2_pdata->handle;
> +
> +	return _dln2_transfer(dln2, h, cmd, obuf, obuf_len, ibuf, ibuf_len);
> +}
> +EXPORT_SYMBOL(dln2_transfer);
> +
> +static int dln2_check_hw(struct dln2_dev *dln2)
> +{
> +	int ret;
> +	__le32 hw_type;
> +	int len = sizeof(hw_type);
> +
> +	ret = _dln2_transfer(dln2, DLN2_HANDLE_CTRL, CMD_GET_DEVICE_VER,
> +			     NULL, 0, &hw_type, &len);
> +	if (ret < 0)
> +		return ret;
> +	if (len < sizeof(hw_type))
> +		return -EREMOTEIO;
> +
> +	if (le32_to_cpu(hw_type) != DLN2_HW_ID) {
> +		dev_err(&dln2->interface->dev, "Device ID 0x%x not supported",

Missing newline in message. Please check throughout all patches. There's
at least one more missing.

> +			le32_to_cpu(hw_type));
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> +
> +static int dln2_print_serialno(struct dln2_dev *dln2)
> +{
> +	int ret;
> +	__le32 serial_no;
> +	int len = sizeof(serial_no);
> +	struct device *dev = &dln2->interface->dev;
> +
> +	ret = _dln2_transfer(dln2, DLN2_HANDLE_CTRL, CMD_GET_DEVICE_SN, NULL, 0,
> +			     &serial_no, &len);
> +	if (ret < 0)
> +		return ret;
> +	if (len < sizeof(serial_no))
> +		return -EREMOTEIO;
> +
> +	dev_info(dev, "Diolan DLN2 serial 0x%x\n", le32_to_cpu(serial_no));
> +
> +	return 0;
> +}
> +
> +static int dln2_hw_init(struct dln2_dev *dln2)
> +{
> +	int ret;
> +
> +	ret = dln2_check_hw(dln2);
> +	if (ret < 0)
> +		return ret;
> +
> +	return dln2_print_serialno(dln2);
> +}
> +
> +static void dln2_free_rx_urbs(struct dln2_dev *dln2)
> +{
> +	int i;
> +
> +	for (i = 0; i < DLN2_MAX_URBS; i++) {
> +		usb_kill_urb(dln2->rx_urb[i]);
> +		usb_free_urb(dln2->rx_urb[i]);
> +		kfree(dln2->rx_buf[i]);
> +	}
> +}
> +
> +static void dln2_free(struct dln2_dev *dln2)
> +{
> +	dln2_free_rx_urbs(dln2);
> +	usb_put_dev(dln2->usb_dev);
> +	kfree(dln2);
> +}
> +
> +static int dln2_setup_rx_urbs(struct dln2_dev *dln2,
> +			      struct usb_host_interface *hostif)
> +{
> +	int i;
> +	const int rx_max_size = DLN2_RX_BUF_SIZE;
> +	struct device *dev = &dln2->interface->dev;
> +
> +	for (i = 0; i < DLN2_MAX_URBS; i++) {
> +		int ret;
> +
> +		dln2->rx_buf[i] = kmalloc(rx_max_size, GFP_KERNEL);
> +		if (!dln2->rx_buf[i])
> +			return -ENOMEM;
> +
> +		dln2->rx_urb[i] = usb_alloc_urb(0, GFP_KERNEL);
> +		if (!dln2->rx_urb[i])
> +			return -ENOMEM;
> +
> +		usb_fill_bulk_urb(dln2->rx_urb[i], dln2->usb_dev,
> +				  usb_rcvbulkpipe(dln2->usb_dev, dln2->ep_in),
> +				  dln2->rx_buf[i], rx_max_size, dln2_rx, dln2);
> +
> +		ret = usb_submit_urb(dln2->rx_urb[i], GFP_KERNEL);
> +		if (ret < 0) {
> +			dev_err(dev, "failed to submit RX URB: %d\n", ret);
> +			return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static struct dln2_platform_data dln2_pdata_gpio = {
> +	.handle = DLN2_HANDLE_GPIO,
> +};
> +
> +/* Only one I2C port seems to be supported on current hardware */
> +static struct dln2_platform_data dln2_pdata_i2c = {
> +	.handle = DLN2_HANDLE_I2C,
> +	.port = 0,
> +};
> +
> +static const struct mfd_cell dln2_devs[] = {
> +	{
> +		.name = "dln2-gpio",
> +		.platform_data = &dln2_pdata_gpio,
> +		.pdata_size = sizeof(struct dln2_platform_data),
> +	},
> +	{
> +		.name = "dln2-i2c",
> +		.platform_data = &dln2_pdata_i2c,
> +		.pdata_size = sizeof(struct dln2_platform_data),
> +	},
> +};
> +
> +static bool dln2_all_rx_slots_free(struct dln2_mod_rx_slots *rxs)
> +{
> +	unsigned long flags;
> +	int slot;
> +
> +	spin_lock_irqsave(&rxs->lock, flags);
> +	slot = find_first_bit(&rxs->bmap, DLN2_MAX_RX_SLOTS);
> +	spin_unlock_irqrestore(&rxs->lock, flags);
> +
> +	if (slot < DLN2_MAX_RX_SLOTS)
> +		return false;
> +
> +	return true;
> +}
> +
> +static void dln2_stop(struct dln2_dev *dln2)
> +{
> +	int i, j;
> +
> +	for (i = 0; i < DLN2_HANDLES; i++) {
> +		struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[i];
> +		unsigned long flags;
> +
> +		spin_lock_irqsave(&rxs->lock, flags);
> +
> +		/* fail further alloc_rx_slot calls */
> +		rxs->disconnected = true;
> +
> +		/* cancel all response waiters */
> +		for (j = 0; j < DLN2_MAX_RX_SLOTS; j++) {
> +			struct dln2_rx_context *rxc = &rxs->slots[j];
> +
> +			if (rxc->connected) {
> +				rxc->urb = NULL;

Don't overload the meaning of urb. Check the disconnected flag were
needed.

Also what would prevent a racing completion handler from setting
rxc->urb again when you release the lock below?

> +				complete(&rxc->done);
> +			}
> +		}
> +		spin_unlock_irqrestore(&rxs->lock, flags);
> +
> +		/* wait for callers to release all rx_slots */
> +		wait_event(rxs->wq, dln2_all_rx_slots_free(rxs));
> +	}
> +}
> +
> +static void dln2_disconnect(struct usb_interface *interface)
> +{
> +	struct dln2_dev *dln2 = usb_get_intfdata(interface);
> +

First set the disconnected flag directly here to prevent any new
transfers from starting.

> +	dln2_stop(dln2);

Then do all the completions (to speed things up somewhat).

Then wait for the transfer counter to reach 0.

> +	mfd_remove_devices(&interface->dev);
> +	dln2_free(dln2);
> +}
> +
> +static int dln2_probe(struct usb_interface *interface,
> +		      const struct usb_device_id *id)
> +{
> +	struct usb_host_interface *hostif = interface->cur_altsetting;
> +	struct device *dev = &interface->dev;
> +	struct dln2_dev *dln2;
> +	int ret;
> +	int i, j;
> +
> +	if (hostif->desc.bInterfaceNumber != 0 ||
> +	    hostif->desc.bNumEndpoints < 2)
> +		return -ENODEV;
> +
> +	dln2 = kzalloc(sizeof(*dln2), GFP_KERNEL);
> +	if (!dln2)
> +		return -ENOMEM;
> +
> +	dln2->ep_out = hostif->endpoint[0].desc.bEndpointAddress;
> +	dln2->ep_in = hostif->endpoint[1].desc.bEndpointAddress;
> +	dln2->usb_dev = usb_get_dev(interface_to_usbdev(interface));
> +	dln2->interface = interface;
> +	usb_set_intfdata(interface, dln2);
> +
> +	for (i = 0; i < DLN2_HANDLES; i++) {
> +		init_waitqueue_head(&dln2->mod_rx_slots[i].wq);
> +		spin_lock_init(&dln2->mod_rx_slots[i].lock);
> +		for (j = 0; j < DLN2_MAX_RX_SLOTS; j++)
> +			init_completion(&dln2->mod_rx_slots[i].slots[j].done);
> +	}
> +
> +	spin_lock_init(&dln2->rx_cb_lock);
> +	INIT_LIST_HEAD(&dln2->rx_cb_list);
> +
> +	ret = dln2_setup_rx_urbs(dln2, hostif);
> +	if (ret) {
> +		dln2_free(dln2);
> +		return ret;
> +	}
> +
> +	ret = dln2_hw_init(dln2);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to initialize hardware\n");
> +		goto out_cleanup;
> +	}
> +
> +	ret = mfd_add_devices(dev, -1, dln2_devs, ARRAY_SIZE(dln2_devs),

Use
	busnum << 8 | devnum

as id for now (as mentioned earlier).

> +			      NULL, 0, NULL);
> +	if (ret != 0) {
> +		dev_err(dev, "Failed to add mfd devices to core.\n");
> +		goto out_cleanup;
> +	}
> +
> +	return 0;
> +
> +out_cleanup:
> +	dln2_free(dln2);
> +
> +	return ret;
> +}

Johan

Re: [PATCH v5 1/4] mfd: add support for Diolan DLN-2 devices

[Johan Hovold]

On Fri, Sep 19, 2014 at 11:22:42PM +0300, Octavian Purdila wrote:
> This patch implements the USB part of the Diolan USB-I2C/SPI/GPIO
> Master Adapter DLN-2. Details about the device can be found here:
> 
> https://www.diolan.com/i2c/i2c_interface.html.
> 
> Information about the USB protocol can be found in the Programmer's
> Reference Manual [1], see section 1.7.
> 
> Because the hardware has a single transmit endpoint and a single
> receive endpoint the communication between the various DLN2 drivers
> and the hardware will be muxed/demuxed by this driver.
> 
> Each DLN2 module will be identified by the handle field within the DLN2
> message header. If a DLN2 module issues multiple commands in parallel
> they will be identified by the echo counter field in the message header.
> 
> The DLN2 modules can use the dln2_transfer() function to issue a
> command and wait for its response. They can also register a callback
> that is going to be called when a specific event id is generated by
> the device (e.g. GPIO interrupts). The device uses handle 0 for
> sending events.
> 
> [1] https://www.diolan.com/downloads/dln-api-manual.pdf
> 
> Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
> ---
>  drivers/mfd/Kconfig      |   9 +
>  drivers/mfd/Makefile     |   1 +
>  drivers/mfd/dln2.c       | 758 +++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/dln2.h |  67 +++++
>  4 files changed, 835 insertions(+)
>  create mode 100644 drivers/mfd/dln2.c
>  create mode 100644 include/linux/mfd/dln2.h
> 
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index de5abf2..7bcf895 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -183,6 +183,15 @@ config MFD_DA9063
>  	  Additional drivers must be enabled in order to use the functionality
>  	  of the device.
>  
> +config MFD_DLN2
> +	tristate "Diolan DLN2 support"
> +	select MFD_CORE
> +	depends on USB
> +	help
> +	  This adds support for Diolan USB-I2C/SPI/GPIO Master Adapter DLN-2.
> +	  Additional drivers must be enabled in order to use the functionality
> +	  of the device.
> +
>  config MFD_MC13XXX
>  	tristate
>  	depends on (SPI_MASTER || I2C)
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index f001487..591988d 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -169,6 +169,7 @@ obj-$(CONFIG_MFD_AS3711)	+= as3711.o
>  obj-$(CONFIG_MFD_AS3722)	+= as3722.o
>  obj-$(CONFIG_MFD_STW481X)	+= stw481x.o
>  obj-$(CONFIG_MFD_IPAQ_MICRO)	+= ipaq-micro.o
> +obj-$(CONFIG_MFD_DLN2)		+= dln2.o
>  
>  intel-soc-pmic-objs		:= intel_soc_pmic_core.o intel_soc_pmic_crc.o
>  obj-$(CONFIG_INTEL_SOC_PMIC)	+= intel-soc-pmic.o
> diff --git a/drivers/mfd/dln2.c b/drivers/mfd/dln2.c
> new file mode 100644
> index 0000000..36c53cd
> --- /dev/null
> +++ b/drivers/mfd/dln2.c
> @@ -0,0 +1,758 @@
> +/*
> + * Driver for the Diolan DLN-2 USB adapter
> + *
> + * Copyright (c) 2014 Intel Corporation
> + *
> + * Derived from:
> + *  i2c-diolan-u2c.c
> + *  Copyright (c) 2010-2011 Ericsson AB
> + *
> + * 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.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/types.h>
> +#include <linux/slab.h>
> +#include <linux/usb.h>
> +#include <linux/i2c.h>
> +#include <linux/mutex.h>
> +#include <linux/platform_device.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/dln2.h>
> +#include <linux/rculist.h>
> +
> +struct dln2_header {
> +	__le16 size;
> +	__le16 id;
> +	__le16 echo;
> +	__le16 handle;
> +} __packed;
> +
> +struct dln2_response {
> +	struct dln2_header hdr;
> +	__le16 result;
> +} __packed;
> +
> +#define DLN2_GENERIC_MODULE_ID		0x00
> +#define DLN2_GENERIC_CMD(cmd)		DLN2_CMD(cmd, DLN2_GENERIC_MODULE_ID)
> +#define CMD_GET_DEVICE_VER		DLN2_GENERIC_CMD(0x30)
> +#define CMD_GET_DEVICE_SN		DLN2_GENERIC_CMD(0x31)
> +
> +#define DLN2_HW_ID			0x200
> +#define DLN2_USB_TIMEOUT		200	/* in ms */
> +#define DLN2_MAX_RX_SLOTS		16
> +#define DLN2_MAX_URBS			16
> +#define DLN2_RX_BUF_SIZE		512
> +
> +#define DLN2_HANDLE_EVENT		0
> +#define DLN2_HANDLE_CTRL		1
> +#define DLN2_HANDLE_GPIO		2
> +#define DLN2_HANDLE_I2C			3
> +#define DLN2_HANDLES			4

This should be an enum.

> +
> +
> +/*
> + * Receive context used between the receive demultiplexer and the
> + * transfer routine. While sending a request the transfer routine
> + * will look for a free receive context and use it to wait for a
> + * response and to receive the URB and thus the response data.
> + */
> +struct dln2_rx_context {
> +	/* completion used to wait a response */

wait for

> +	struct completion done;
> +
> +	/* if non-NULL the URB contains the response */
> +	struct urb *urb;
> +
> +	/* if true then this context is used to wait for a response */
> +	bool connected;

Now that you have a disconnected flag, perhaps you can rename this to
something more descriptive as, for example, in_use.

> +
> +	/* cancel waiting for a response, e.g. on USB disconnect */
> +	bool cancel;

You this new field now, but never use it.

> +};
> +
> +/*
> + * Receive contexts for a particular DLN2 module (i2c, gpio, etc.). We
> + * use the handle header field to indentify the module in

identify

> + * dln2_dev.mod_rx_slots and then the echo header field to index the
> + * slots field and find the receive context for a particular
> + * request.
> + */
> +struct dln2_mod_rx_slots {
> +	/* RX slots bitmap */
> +	unsigned long bmap;
> +
> +	/* used to wait for a free RX slot */
> +	wait_queue_head_t wq;
> +
> +	/* used to wait for an RX operation to complete */
> +	struct dln2_rx_context slots[DLN2_MAX_RX_SLOTS];
> +
> +	/* device has been disconnected */
> +	bool disconnected;

This belongs in the dln2_dev struct.

I think you're overcomplicating the disconnect handling by intertwining
it with your slots.

Add a lock, an active-transfer counter, a disconnected flag, and a wait
queue to struct dln2_dev.

More below.

> +
> +	/* avoid races between free_rx_slot, dln2_rx_transfer and dln2_stop */
> +	spinlock_t lock;
> +};
> +
> +struct dln2_dev {
> +	struct usb_device *usb_dev;
> +	struct usb_interface *interface;
> +	u8 ep_in;
> +	u8 ep_out;
> +
> +	struct urb *rx_urb[DLN2_MAX_URBS];
> +	void *rx_buf[DLN2_MAX_URBS];
> +
> +	struct dln2_mod_rx_slots mod_rx_slots[DLN2_HANDLES];
> +
> +	struct list_head rx_cb_list;
> +	spinlock_t rx_cb_lock;
> +};
> +
> +static bool find_free_slot(struct dln2_mod_rx_slots *rxs, int *slot)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&rxs->lock, flags);
> +
> +	if (rxs->disconnected) {

Check the global disconnected flag. Locking not needed.

> +		*slot = -ECONNRESET;

-ENODEV

> +		goto out;
> +	}
> +
> +	*slot = find_first_zero_bit(&rxs->bmap, DLN2_MAX_RX_SLOTS);
> +
> +	if (*slot < DLN2_MAX_RX_SLOTS) {
> +		struct dln2_rx_context *rxc = &rxs->slots[*slot];
> +
> +		set_bit(*slot, &rxs->bmap);
> +		rxc->connected = true;
> +	}
> +
> +out:
> +	spin_unlock_irqrestore(&rxs->lock, flags);
> +
> +	return *slot < DLN2_MAX_RX_SLOTS;
> +}
> +
> +static int alloc_rx_slot(struct dln2_mod_rx_slots *rxs)
> +{
> +	int ret;
> +	int slot;
> +
> +	/*
> +	 * No need to timeout here, the wait is bounded by the timeout
> +	 * in _dln2_transfer.
> +	 */
> +	ret = wait_event_interruptible(rxs->wq, find_free_slot(rxs, &slot));
> +	if (ret < 0)
> +		return ret;
> +
> +	return slot;
> +}
> +
> +static void free_rx_slot(struct dln2_dev *dln2, struct dln2_mod_rx_slots *rxs,
> +			 int slot)
> +{
> +	struct urb *urb = NULL;
> +	unsigned long flags;
> +	struct dln2_rx_context *rxc;
> +	struct device *dev = &dln2->interface->dev;
> +	int ret;
> +
> +	spin_lock_irqsave(&rxs->lock, flags);
> +
> +	clear_bit(slot, &rxs->bmap);
> +
> +	rxc = &rxs->slots[slot];
> +	rxc->connected = false;
> +	urb = rxc->urb;
> +	rxc->urb = NULL;
> +	reinit_completion(&rxc->done);
> +
> +	spin_unlock_irqrestore(&rxs->lock, flags);
> +
> +	if (urb) {
> +		ret = usb_submit_urb(urb, GFP_KERNEL);
> +		if (ret < 0)
> +			dev_err(dev, "failed to re-submit RX URB: %d\n", ret);
> +	}
> +
> +	wake_up_interruptible(&rxs->wq);
> +}

Could you move these three functions just above _dln2_transfer, which is
the only function they are used in?

> +
> +struct dln2_rx_cb_entry {
> +	struct list_head list;
> +	u16 id;
> +	struct platform_device *pdev;
> +	dln2_rx_cb_t callback;
> +};
> +
> +int dln2_register_event_cb(struct platform_device *pdev, u16 id,
> +			   dln2_rx_cb_t rx_cb)
> +{
> +	struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
> +	struct dln2_rx_cb_entry *i, *new;
> +	unsigned long flags;
> +	int ret = 0;
> +
> +	new = kmalloc(sizeof(*new), GFP_KERNEL);
> +	if (!new)
> +		return -ENOMEM;
> +
> +	new->id = id;
> +	new->callback = rx_cb;
> +	new->pdev = pdev;
> +
> +	spin_lock_irqsave(&dln2->rx_cb_lock, flags);
> +
> +	list_for_each_entry_rcu(i, &dln2->rx_cb_list, list) {

No need to use the _rcu version on the update side.

> +		if (i->id == id) {
> +			ret = -EBUSY;
> +			break;
> +		}
> +	}
> +
> +	if (!ret)
> +		list_add_rcu(&new->list, &dln2->rx_cb_list);
> +
> +	spin_unlock_irqrestore(&dln2->rx_cb_lock, flags);
> +
> +	if (ret)
> +		kfree(new);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(dln2_register_event_cb);
> +
> +void dln2_unregister_event_cb(struct platform_device *pdev, u16 id)
> +{
> +	struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
> +	struct dln2_rx_cb_entry *i;
> +	unsigned long flags;
> +	bool found = false;
> +
> +	spin_lock_irqsave(&dln2->rx_cb_lock, flags);
> +
> +	list_for_each_entry_rcu(i, &dln2->rx_cb_list, list) {

No need to use the _rcu version on the update side.

> +		if (i->id == id) {
> +			list_del_rcu(&i->list);
> +			found = true;
> +			break;
> +		}
> +	}
> +
> +	spin_unlock_irqrestore(&dln2->rx_cb_lock, flags);
> +
> +	if (found) {
> +		synchronize_rcu();
> +		kfree(i);
> +	}
> +}
> +EXPORT_SYMBOL(dln2_unregister_event_cb);
> +
> +static void dln2_rx_transfer(struct dln2_dev *dln2, struct urb *urb,
> +			     u16 handle, u16 rx_slot)
> +{
> +	struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
> +	struct dln2_rx_context *rxc;
> +	struct device *dev = &dln2->interface->dev;
> +	int err;
> +
> +	spin_lock(&rxs->lock);
> +	rxc = &rxs->slots[rx_slot];
> +	if (rxc->connected) {
> +		rxc->urb = urb;
> +		complete(&rxc->done);
> +	} else {
> +		dev_warn(dev, "dropping response %d/%d", handle, rx_slot);
> +		err = usb_submit_urb(urb, GFP_ATOMIC);
> +		if (err < 0)
> +			dev_err(dev, "failed to re-submit RX URB: %d\n", err);
> +	}
> +	spin_unlock(&rxs->lock);
> +}
> +
> +static void dln2_run_rx_callbacks(struct dln2_dev *dln2, u16 id, u16 echo,
> +				  void *data, int len)
> +{
> +	struct dln2_rx_cb_entry *i;
> +
> +	rcu_read_lock();
> +
> +	list_for_each_entry_rcu(i, &dln2->rx_cb_list, list)
> +		if (i->id == id)
> +			i->callback(i->pdev, echo, data, len);
> +
> +	rcu_read_unlock();
> +}
> +
> +static void dln2_rx(struct urb *urb)
> +{
> +	int err;
> +	struct dln2_dev *dln2 = urb->context;
> +	struct dln2_header *hdr = urb->transfer_buffer;
> +	struct device *dev = &dln2->interface->dev;
> +	u16 id, echo, handle, size;
> +	u8 *data;
> +	int len;
> +
> +	switch (urb->status) {
> +	case 0:
> +		/* success */
> +		break;
> +	case -ECONNRESET:
> +	case -ENOENT:
> +	case -ESHUTDOWN:
> +	case -EPIPE:
> +		/* this urb is terminated, clean up */
> +		dev_dbg(dev, "urb shutting down with status %d\n", urb->status);
> +		return;
> +	default:
> +		dev_dbg(dev, "nonzero urb status received %d\n", urb->status);
> +		goto out;
> +	}
> +
> +	if (urb->actual_length < sizeof(struct dln2_header)) {
> +		dev_err(dev, "short response: %d\n", urb->actual_length);
> +		goto out;
> +	}
> +
> +	handle = le16_to_cpu(hdr->handle);
> +	id = le16_to_cpu(hdr->id);
> +	echo = le16_to_cpu(hdr->echo);
> +	size = le16_to_cpu(hdr->size);
> +
> +	if (size != urb->actual_length) {
> +		dev_err(dev, "size mismatch: handle %x cmd %x echo %x size %d actual %d\n",
> +			handle, id, echo, size, urb->actual_length);
> +		goto out;
> +	}
> +
> +	if (handle >= DLN2_HANDLES) {
> +		dev_warn(dev, "RX: invalid handle %d\n", handle);
> +		goto out;
> +	}
> +
> +	data = urb->transfer_buffer + sizeof(struct dln2_header);
> +	len = urb->actual_length - sizeof(struct dln2_header);
> +
> +	if (handle == DLN2_HANDLE_EVENT) {
> +		dln2_run_rx_callbacks(dln2, id, echo, data, len);
> +		err = usb_submit_urb(urb, GFP_ATOMIC);
> +		if (err < 0)
> +			goto out_submit_failed;
> +	} else {
> +		dln2_rx_transfer(dln2, urb, handle, echo);
> +	}
> +
> +	return;
> +
> +out:
> +	err = usb_submit_urb(urb, GFP_ATOMIC);
> +out_submit_failed:
> +	if (err < 0)
> +		dev_err(dev, "failed to re-submit RX URB: %d\n", err);
> +}
> +
> +static void *dln2_prep_buf(u16 handle, u16 cmd, u16 echo, const void *obuf,
> +			   int *obuf_len, gfp_t gfp)
> +{
> +	int len;
> +	void *buf;
> +	struct dln2_header *hdr;
> +
> +	len = *obuf_len + sizeof(*hdr);
> +	buf = kmalloc(len, gfp);
> +	if (!buf)
> +		return NULL;
> +
> +	hdr = (struct dln2_header *)buf;
> +	hdr->id = cpu_to_le16(cmd);
> +	hdr->size = cpu_to_le16(len);
> +	hdr->echo = cpu_to_le16(echo);
> +	hdr->handle = cpu_to_le16(handle);
> +
> +	memcpy(buf + sizeof(*hdr), obuf, *obuf_len);
> +
> +	*obuf_len = len;
> +
> +	return buf;
> +}
> +
> +static int dln2_send_wait(struct dln2_dev *dln2, u16 handle, u16 cmd, u16 echo,
> +			  const void *obuf, int obuf_len)
> +{
> +	int ret = 0;
> +	int len = obuf_len;
> +	void *buf;
> +	int actual;
> +
> +	buf = dln2_prep_buf(handle, cmd, echo, obuf, &len, GFP_KERNEL);
> +	if (!buf)
> +		return -ENOMEM;
> +
> +	ret = usb_bulk_msg(dln2->usb_dev,
> +			   usb_sndbulkpipe(dln2->usb_dev, dln2->ep_out),
> +			   buf, len, &actual, DLN2_USB_TIMEOUT);
> +
> +	kfree(buf);
> +
> +	return ret;
> +}
> +
> +static int _dln2_transfer(struct dln2_dev *dln2, u16 handle, u16 cmd,
> +			  const void *obuf, unsigned obuf_len,
> +			  void *ibuf, unsigned *ibuf_len)
> +{
> +	int ret = 0;
> +	u16 result;
> +	int rx_slot;
> +	unsigned long flags;
> +	struct dln2_response *rsp;
> +	struct dln2_rx_context *rxc;
> +	struct device *dev;
> +	const int timeout = DLN2_USB_TIMEOUT * HZ / 1000;
> +	struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
> +

Check the disconnected flag before incrementing the transfer count
(while holding the device lock) here. Then decrement counter before
returning and wake up an waiters if disconnected below.

That is sufficient to implement wait-until-io-has-completed. Anything
else you do below and in the helper functions is only to speed things
up at disconnect (and can be done without locking the device).

> +	rx_slot = alloc_rx_slot(rxs);
> +	if (rx_slot < 0)
> +		return rx_slot;
> +
> +	dev = &dln2->interface->dev;
> +
> +	ret = dln2_send_wait(dln2, handle, cmd, rx_slot, obuf, obuf_len);
> +	if (ret < 0) {
> +		free_rx_slot(dln2, rxs, rx_slot);

goto out_free_rx_slot

> +		dev_err(dev, "USB write failed: %d", ret);
> +		return ret;
> +	}
> +
> +	rxc = &rxs->slots[rx_slot];
> +
> +	ret = wait_for_completion_interruptible_timeout(&rxc->done, timeout);
> +	if (ret <= 0) {
> +		if (!ret)
> +			ret = -ETIMEDOUT;
> +		goto out_free_rx_slot;
> +	}
> +
> +	spin_lock_irqsave(&rxs->lock, flags);
> +
> +	if (!rxc->urb) {

Just check the disconnected flag directly here. Locking not needed (see
below).

> +		ret = -ECONNRESET;

-ENODEV

> +		spin_unlock_irqrestore(&rxs->lock, flags);
> +		goto out_free_rx_slot;
> +	}
> +
> +	/* if we got here we know that the response header has been checked */
> +	rsp = rxc->urb->transfer_buffer;
> +
> +	spin_unlock_irqrestore(&rxs->lock, flags);
> +
> +	if (rsp->hdr.size < sizeof(*rsp)) {
> +		ret = -EPROTO;
> +		goto out_free_rx_slot;
> +	}
> +
> +	result = le16_to_cpu(rsp->result);
> +	if (result) {
> +		dev_dbg(dev, "%d received response with error %d\n",
> +			handle, result);
> +		ret = -EREMOTEIO;
> +		goto out_free_rx_slot;
> +	}
> +
> +	if (!ibuf) {
> +		ret = 0;
> +		goto out_free_rx_slot;
> +	}
> +
> +	if (*ibuf_len > rsp->hdr.size - sizeof(*rsp))
> +		*ibuf_len = rsp->hdr.size - sizeof(*rsp);
> +
> +	memcpy(ibuf, rsp + 1, *ibuf_len);
> +
> +out_free_rx_slot:
> +	free_rx_slot(dln2, rxs, rx_slot);
> +
> +	return ret;
> +}
> +
> +int dln2_transfer(struct platform_device *pdev, u16 cmd,
> +		  const void *obuf, unsigned obuf_len,
> +		  void *ibuf, unsigned *ibuf_len)
> +{
> +	struct dln2_platform_data *dln2_pdata;
> +	struct dln2_dev *dln2;
> +	u16 h;
> +
> +	dln2 = dev_get_drvdata(pdev->dev.parent);
> +	dln2_pdata = dev_get_platdata(&pdev->dev);
> +	h = dln2_pdata->handle;
> +
> +	return _dln2_transfer(dln2, h, cmd, obuf, obuf_len, ibuf, ibuf_len);
> +}
> +EXPORT_SYMBOL(dln2_transfer);
> +
> +static int dln2_check_hw(struct dln2_dev *dln2)
> +{
> +	int ret;
> +	__le32 hw_type;
> +	int len = sizeof(hw_type);
> +
> +	ret = _dln2_transfer(dln2, DLN2_HANDLE_CTRL, CMD_GET_DEVICE_VER,
> +			     NULL, 0, &hw_type, &len);
> +	if (ret < 0)
> +		return ret;
> +	if (len < sizeof(hw_type))
> +		return -EREMOTEIO;
> +
> +	if (le32_to_cpu(hw_type) != DLN2_HW_ID) {
> +		dev_err(&dln2->interface->dev, "Device ID 0x%x not supported",

Missing newline in message. Please check throughout all patches. There's
at least one more missing.

> +			le32_to_cpu(hw_type));
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> +
> +static int dln2_print_serialno(struct dln2_dev *dln2)
> +{
> +	int ret;
> +	__le32 serial_no;
> +	int len = sizeof(serial_no);
> +	struct device *dev = &dln2->interface->dev;
> +
> +	ret = _dln2_transfer(dln2, DLN2_HANDLE_CTRL, CMD_GET_DEVICE_SN, NULL, 0,
> +			     &serial_no, &len);
> +	if (ret < 0)
> +		return ret;
> +	if (len < sizeof(serial_no))
> +		return -EREMOTEIO;
> +
> +	dev_info(dev, "Diolan DLN2 serial 0x%x\n", le32_to_cpu(serial_no));
> +
> +	return 0;
> +}
> +
> +static int dln2_hw_init(struct dln2_dev *dln2)
> +{
> +	int ret;
> +
> +	ret = dln2_check_hw(dln2);
> +	if (ret < 0)
> +		return ret;
> +
> +	return dln2_print_serialno(dln2);
> +}
> +
> +static void dln2_free_rx_urbs(struct dln2_dev *dln2)
> +{
> +	int i;
> +
> +	for (i = 0; i < DLN2_MAX_URBS; i++) {
> +		usb_kill_urb(dln2->rx_urb[i]);
> +		usb_free_urb(dln2->rx_urb[i]);
> +		kfree(dln2->rx_buf[i]);
> +	}
> +}
> +
> +static void dln2_free(struct dln2_dev *dln2)
> +{
> +	dln2_free_rx_urbs(dln2);
> +	usb_put_dev(dln2->usb_dev);
> +	kfree(dln2);
> +}
> +
> +static int dln2_setup_rx_urbs(struct dln2_dev *dln2,
> +			      struct usb_host_interface *hostif)
> +{
> +	int i;
> +	const int rx_max_size = DLN2_RX_BUF_SIZE;
> +	struct device *dev = &dln2->interface->dev;
> +
> +	for (i = 0; i < DLN2_MAX_URBS; i++) {
> +		int ret;
> +
> +		dln2->rx_buf[i] = kmalloc(rx_max_size, GFP_KERNEL);
> +		if (!dln2->rx_buf[i])
> +			return -ENOMEM;
> +
> +		dln2->rx_urb[i] = usb_alloc_urb(0, GFP_KERNEL);
> +		if (!dln2->rx_urb[i])
> +			return -ENOMEM;
> +
> +		usb_fill_bulk_urb(dln2->rx_urb[i], dln2->usb_dev,
> +				  usb_rcvbulkpipe(dln2->usb_dev, dln2->ep_in),
> +				  dln2->rx_buf[i], rx_max_size, dln2_rx, dln2);
> +
> +		ret = usb_submit_urb(dln2->rx_urb[i], GFP_KERNEL);
> +		if (ret < 0) {
> +			dev_err(dev, "failed to submit RX URB: %d\n", ret);
> +			return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static struct dln2_platform_data dln2_pdata_gpio = {
> +	.handle = DLN2_HANDLE_GPIO,
> +};
> +
> +/* Only one I2C port seems to be supported on current hardware */
> +static struct dln2_platform_data dln2_pdata_i2c = {
> +	.handle = DLN2_HANDLE_I2C,
> +	.port = 0,
> +};
> +
> +static const struct mfd_cell dln2_devs[] = {
> +	{
> +		.name = "dln2-gpio",
> +		.platform_data = &dln2_pdata_gpio,
> +		.pdata_size = sizeof(struct dln2_platform_data),
> +	},
> +	{
> +		.name = "dln2-i2c",
> +		.platform_data = &dln2_pdata_i2c,
> +		.pdata_size = sizeof(struct dln2_platform_data),
> +	},
> +};
> +
> +static bool dln2_all_rx_slots_free(struct dln2_mod_rx_slots *rxs)
> +{
> +	unsigned long flags;
> +	int slot;
> +
> +	spin_lock_irqsave(&rxs->lock, flags);
> +	slot = find_first_bit(&rxs->bmap, DLN2_MAX_RX_SLOTS);
> +	spin_unlock_irqrestore(&rxs->lock, flags);
> +
> +	if (slot < DLN2_MAX_RX_SLOTS)
> +		return false;
> +
> +	return true;
> +}
> +
> +static void dln2_stop(struct dln2_dev *dln2)
> +{
> +	int i, j;
> +
> +	for (i = 0; i < DLN2_HANDLES; i++) {
> +		struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[i];
> +		unsigned long flags;
> +
> +		spin_lock_irqsave(&rxs->lock, flags);
> +
> +		/* fail further alloc_rx_slot calls */
> +		rxs->disconnected = true;
> +
> +		/* cancel all response waiters */
> +		for (j = 0; j < DLN2_MAX_RX_SLOTS; j++) {
> +			struct dln2_rx_context *rxc = &rxs->slots[j];
> +
> +			if (rxc->connected) {
> +				rxc->urb = NULL;

Don't overload the meaning of urb. Check the disconnected flag were
needed.

Also what would prevent a racing completion handler from setting
rxc->urb again when you release the lock below?

> +				complete(&rxc->done);
> +			}
> +		}
> +		spin_unlock_irqrestore(&rxs->lock, flags);
> +
> +		/* wait for callers to release all rx_slots */
> +		wait_event(rxs->wq, dln2_all_rx_slots_free(rxs));
> +	}
> +}
> +
> +static void dln2_disconnect(struct usb_interface *interface)
> +{
> +	struct dln2_dev *dln2 = usb_get_intfdata(interface);
> +

First set the disconnected flag directly here to prevent any new
transfers from starting.

> +	dln2_stop(dln2);

Then do all the completions (to speed things up somewhat).

Then wait for the transfer counter to reach 0.

> +	mfd_remove_devices(&interface->dev);
> +	dln2_free(dln2);
> +}
> +
> +static int dln2_probe(struct usb_interface *interface,
> +		      const struct usb_device_id *id)
> +{
> +	struct usb_host_interface *hostif = interface->cur_altsetting;
> +	struct device *dev = &interface->dev;
> +	struct dln2_dev *dln2;
> +	int ret;
> +	int i, j;
> +
> +	if (hostif->desc.bInterfaceNumber != 0 ||
> +	    hostif->desc.bNumEndpoints < 2)
> +		return -ENODEV;
> +
> +	dln2 = kzalloc(sizeof(*dln2), GFP_KERNEL);
> +	if (!dln2)
> +		return -ENOMEM;
> +
> +	dln2->ep_out = hostif->endpoint[0].desc.bEndpointAddress;
> +	dln2->ep_in = hostif->endpoint[1].desc.bEndpointAddress;
> +	dln2->usb_dev = usb_get_dev(interface_to_usbdev(interface));
> +	dln2->interface = interface;
> +	usb_set_intfdata(interface, dln2);
> +
> +	for (i = 0; i < DLN2_HANDLES; i++) {
> +		init_waitqueue_head(&dln2->mod_rx_slots[i].wq);
> +		spin_lock_init(&dln2->mod_rx_slots[i].lock);
> +		for (j = 0; j < DLN2_MAX_RX_SLOTS; j++)
> +			init_completion(&dln2->mod_rx_slots[i].slots[j].done);
> +	}
> +
> +	spin_lock_init(&dln2->rx_cb_lock);
> +	INIT_LIST_HEAD(&dln2->rx_cb_list);
> +
> +	ret = dln2_setup_rx_urbs(dln2, hostif);
> +	if (ret) {
> +		dln2_free(dln2);
> +		return ret;
> +	}
> +
> +	ret = dln2_hw_init(dln2);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to initialize hardware\n");
> +		goto out_cleanup;
> +	}
> +
> +	ret = mfd_add_devices(dev, -1, dln2_devs, ARRAY_SIZE(dln2_devs),

Use
	busnum << 8 | devnum

as id for now (as mentioned earlier).

> +			      NULL, 0, NULL);
> +	if (ret != 0) {
> +		dev_err(dev, "Failed to add mfd devices to core.\n");
> +		goto out_cleanup;
> +	}
> +
> +	return 0;
> +
> +out_cleanup:
> +	dln2_free(dln2);
> +
> +	return ret;
> +}

Johan

Re: [PATCH v5 2/4] i2c: add support for Diolan DLN-2 USB-I2C adapter

[Johan Hovold]

On Fri, Sep 19, 2014 at 11:22:43PM +0300, Octavian Purdila wrote:

> +struct dln2_i2c {
> +	struct platform_device *pdev;
> +	struct i2c_adapter adapter;
> +	u32 freq;
> +	u32 min_freq;
> +	u32 max_freq;
> +	/*
> +	 * Buffer to hold the packet for read or write transfers. One
> +	 * is enough since we can't have multiple transfers in
> +	 * parallel on the i2c adapter.
> +	 */
> +	union {
> +		struct {
> +			u8 port;
> +			u8 addr;
> +			u8 mem_addr_len;
> +			__le32 mem_addr;
> +			__le16 buf_len;
> +			u8 buf[DLN2_I2C_MAX_XFER_SIZE];
> +		} __packed tx;
> +		struct {
> +			__le16 buf_len;
> +			u8 buf[DLN2_I2C_MAX_XFER_SIZE];
> +		} __packed rx;
> +	} *buf;

Please declare these structs separately from the dln2_i2c struct so you
can use temporary pointers below.

Perhaps just allocate a large enough buffer (or page) here and keep you
transfer-buffer declarations in the two functions where they are used if
you prefer.

> +};
>
> +static int dln2_i2c_enable(struct dln2_i2c *dln2, bool enable)
> +{
> +	struct dln2_platform_data *pdata = dev_get_platdata(&dln2->pdev->dev);
> +	int ret;
> +	u8 port;
> +	u16 cmd;
> +
> +	port = pdata->port;

Store the port number in the dln2_i2c struct rather than access it
through the platform data for every I/O operation.

> +
> +	if (enable)
> +		cmd = DLN2_I2C_ENABLE;
> +	else
> +		cmd = DLN2_I2C_DISABLE;
> +
> +	ret = dln2_transfer(dln2->pdev, cmd, &port, sizeof(port), NULL, NULL);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int dln2_i2c_set_frequency(struct dln2_i2c *dln2, u32 freq)
> +{
> +	int ret;
> +	struct tx_data {
> +		u8 port;
> +		__le32 freq;
> +	} __packed tx;
> +	struct dln2_platform_data *pdata = dev_get_platdata(&dln2->pdev->dev);
> +
> +	tx.port = pdata->port;
> +	tx.freq = cpu_to_le32(freq);
> +
> +	ret = dln2_transfer(dln2->pdev, DLN2_I2C_SET_FREQUENCY, &tx, sizeof(tx),
> +			    NULL, NULL);
> +	if (ret < 0)
> +		return ret;
> +
> +	dln2->freq = freq;
> +
> +	return 0;
> +}
> +
> +static int dln2_i2c_get_freq(struct dln2_i2c *dln2, u16 cmd, u32 *res)
> +{
> +	int ret;
> +	struct dln2_platform_data *pdata = dev_get_platdata(&dln2->pdev->dev);
> +	u8 port = pdata->port;
> +	__le32 freq;
> +	unsigned len = sizeof(freq);
> +
> +	ret = dln2_transfer(dln2->pdev, cmd, &port, sizeof(port),
> +			    &freq, &len);
> +	if (ret < 0)
> +		return ret;
> +	if (len < sizeof(freq))
> +		return -EPROTO;
> +
> +	*res = le32_to_cpu(freq);
> +
> +	return 0;
> +}
> +
> +static int dln2_i2c_setup(struct dln2_i2c *dln2)
> +{
> +	int ret;
> +
> +	ret = dln2_i2c_enable(dln2, false);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = dln2_i2c_get_freq(dln2, DLN2_I2C_GET_MIN_FREQUENCY,
> +				&dln2->min_freq);
> +	if (ret < 0)
> +		return 0;

return ret

> +
> +	ret = dln2_i2c_get_freq(dln2, DLN2_I2C_GET_MAX_FREQUENCY,
> +				&dln2->max_freq);
> +	if (ret < 0)
> +		return 0;

return ret

> +
> +	ret = dln2_i2c_set_frequency(dln2, DLN2_I2C_FREQ_STD);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = dln2_i2c_enable(dln2, true);
> +
> +	return ret;
> +}
> +
> +static int dln2_i2c_write(struct dln2_i2c *dln2, u8 addr,
> +			  u8 *data, u16 data_len)
> +{
> +	struct dln2_platform_data *pdata = dev_get_platdata(&dln2->pdev->dev);
> +	int ret;
> +	unsigned len;
> +
> +	dln2->buf->tx.port = pdata->port;
> +	dln2->buf->tx.addr = addr;
> +	dln2->buf->tx.mem_addr_len = 0;
> +	dln2->buf->tx.mem_addr = 0;
> +	dln2->buf->tx.buf_len = cpu_to_le16(data_len);
> +	memcpy(dln2->buf->tx.buf, data, data_len);
> +
> +	len = sizeof(dln2->buf->tx) + data_len - DLN2_I2C_MAX_XFER_SIZE;
> +	ret = dln2_transfer(dln2->pdev, DLN2_I2C_WRITE, &dln2->buf->tx, len,
> +			    NULL, NULL);

Use a temporary pointer to the tx struct above for readability.

> +	if (ret < 0)
> +		return ret;
> +
> +	return data_len;
> +}
> +
> +static int dln2_i2c_read(struct dln2_i2c *dln2, u16 addr, u8 *data,
> +			 u16 data_len)
> +{
> +	struct dln2_platform_data *pdata = dev_get_platdata(&dln2->pdev->dev);
> +	int ret;
> +	struct {
> +		u8 port;
> +		u8 addr;
> +		u8 mem_addr_len;
> +		__le32 mem_addr;
> +		__le16 buf_len;
> +	} __packed tx;
> +	unsigned rx_len;
> +
> +	tx.port = pdata->port;
> +	tx.addr = addr;
> +	tx.mem_addr_len = 0;
> +	tx.mem_addr = 0;
> +	tx.buf_len = cpu_to_le16(data_len);
> +
> +	rx_len = sizeof(dln2->buf->rx);
> +
> +	ret = dln2_transfer(dln2->pdev, DLN2_I2C_READ, &tx, sizeof(tx),
> +			    &dln2->buf->rx, &rx_len);
> +	if (ret < 0)
> +		return ret;
> +	if (rx_len < sizeof(dln2->buf->rx.buf_len) + data_len)
> +		return -EPROTO;
> +	if (le16_to_cpu(dln2->buf->rx.buf_len) != data_len)
> +		return -EPROTO;
> +
> +	memcpy(data, dln2->buf->rx.buf, data_len);'

Use a temporary pointer to the rx struct above.

> +
> +	return data_len;
> +}

[...]

> +static DEVICE_ATTR_RW(dln2_i2c_freq);

Any new sysfs attribute must to be documented under Documentation/ABI.

[...]

> +static struct platform_driver dln2_i2c_driver = {
> +	.driver.name	= "dln2-i2c",
> +	.driver.owner	= THIS_MODULE,

No need to set the owner field when using the module_platform_driver
macro.

> +	.probe		= dln2_i2c_probe,
> +	.remove		= dln2_i2c_remove,
> +};
> +
> +module_platform_driver(dln2_i2c_driver);
> +
> +MODULE_AUTHOR("Laurentiu Palcu <laurentiu.palcu@intel.com>");
> +MODULE_DESCRIPTION("Driver for the Diolan DLN2 I2C master interface");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:dln2-i2c");

Johan

Re: [PATCH v5 3/4] gpiolib: add irq_not_threaded flag to gpio_chip

[Johan Hovold]

On Wed, Sep 24, 2014 at 10:54:51AM +0200, Linus Walleij wrote:
> On Fri, Sep 19, 2014 at 10:22 PM, Octavian Purdila
> <octavian.purdila@intel.com> wrote:
> 
> > Some GPIO chips (e.g. the DLN2 USB adapter) have blocking get/set
> > operation but do not need a threaded irq handler.
> >
> > Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
> 
> Usually I don't apply patches adding interfaces with no users, but
> this seems very useful, so patch applied. I guess your driver will
> appear on v3.19+ so then you can rely on this having been merged
> for v3.18.

Octavian, please include this one in any future revision of you series
so that it is self-contained (at least until v3.18-rc1 is out)
nonetheless.

Thanks,
Johan

Re: [PATCH v5 4/4] gpio: add support for the Diolan DLN-2 USB GPIO driver

[Johan Hovold]

On Fri, Sep 19, 2014 at 11:22:45PM +0300, Octavian Purdila wrote:

> +struct dln2_gpio {
> +	struct platform_device *pdev;
> +	struct gpio_chip gpio;
> +
> +	/*
> +	 * Cache pin direction to save us one transfer, since the
> +	 * hardware has separate commands to read the in and out
> +	 * values. Bit set for out, bit clear for in.
> +	 */
> +	DECLARE_BITMAP(pin_dir, DLN2_GPIO_MAX_PINS);

Using the more common name output_enabled might be preferred? Then you
can even get rid of (part of) the comment.

> +
> +	DECLARE_BITMAP(irqs_masked, DLN2_GPIO_MAX_PINS);
> +	DECLARE_BITMAP(irqs_enabled, DLN2_GPIO_MAX_PINS);
> +	DECLARE_BITMAP(irqs_pending, DLN2_GPIO_MAX_PINS);
> +	struct dln2_irq_work *irq_work;
> +};

[...]

> +#define DLN2_GPIO_DIRECTION_IN		0
> +#define DLN2_GPIO_DIRECTION_OUT		1
> +
> +static int dln2_gpio_request(struct gpio_chip *chip, unsigned offset)
> +{
> +	struct dln2_gpio *dln2 = container_of(chip, struct dln2_gpio, gpio);
> +	struct dln2_gpio_pin req = {
> +		.pin = cpu_to_le16(offset),
> +	};
> +	struct dln2_gpio_pin_val rsp;
> +	int len = sizeof(rsp);
> +	int ret;
> +
> +	ret = dln2_gpio_pin_cmd(dln2, DLN2_GPIO_PIN_ENABLE, offset);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* cache the pin direction */
> +	ret = dln2_transfer(dln2->pdev, DLN2_GPIO_PIN_GET_DIRECTION,
> +			    &req, sizeof(req), &rsp, &len);
> +	if (ret < 0)
> +		return ret;
> +	if (len < sizeof(rsp) || req.pin != rsp.pin)
> +		return -EPROTO;

Disable the pin?

> +
> +	switch (rsp.value) {
> +	case DLN2_GPIO_DIRECTION_IN:
> +		clear_bit(offset, dln2->pin_dir);
> +		return 0;
> +	case DLN2_GPIO_DIRECTION_OUT:
> +		set_bit(offset, dln2->pin_dir);
> +		return 0;
> +	default:
> +		return -EPROTO;

Disable the pin?

> +	}
> +}

[...]

> +static struct platform_driver dln2_gpio_driver = {
> +	.driver.name	= "dln2-gpio",
> +	.driver.owner	= THIS_MODULE,

No need to set the owner field when using the module_platform_driver
macro.

> +	.probe		= dln2_gpio_probe,
> +	.remove		= dln2_gpio_remove,
> +};
> +
> +module_platform_driver(dln2_gpio_driver);
> +
> +MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com");
> +MODULE_DESCRIPTION("Driver for the Diolan DLN2 GPIO interface");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:dln2-gpio");

Johan

Re: [PATCH v5 1/4] mfd: add support for Diolan DLN-2 devices

[Octavian Purdila]

On Wed, Sep 24, 2014 at 1:48 PM, Johan Hovold <johan-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote:
> On Fri, Sep 19, 2014 at 11:22:42PM +0300, Octavian Purdila wrote:

<snip>

>> + * dln2_dev.mod_rx_slots and then the echo header field to index the
>> + * slots field and find the receive context for a particular
>> + * request.
>> + */
>> +struct dln2_mod_rx_slots {
>> +     /* RX slots bitmap */
>> +     unsigned long bmap;
>> +
>> +     /* used to wait for a free RX slot */
>> +     wait_queue_head_t wq;
>> +
>> +     /* used to wait for an RX operation to complete */
>> +     struct dln2_rx_context slots[DLN2_MAX_RX_SLOTS];
>> +
>> +     /* device has been disconnected */
>> +     bool disconnected;
>
> This belongs in the dln2_dev struct.
>
> I think you're overcomplicating the disconnect handling by intertwining
> it with your slots.
>
> Add a lock, an active-transfer counter, a disconnected flag, and a wait
> queue to struct dln2_dev.
>

I agree that disconnected is better suited in dln2_dev.

However, I don't think that we need the active-transfer counter and a
new wait queue. We can simply use the existing waiting queues and the
implicit alloc_rx_slot()/free_rx_slot() calls to see if we are still
waiting for I/O.

<snip>

>> +
>> +static int _dln2_transfer(struct dln2_dev *dln2, u16 handle, u16 cmd,
>> +                       const void *obuf, unsigned obuf_len,
>> +                       void *ibuf, unsigned *ibuf_len)
>> +{
>> +     int ret = 0;
>> +     u16 result;
>> +     int rx_slot;
>> +     unsigned long flags;
>> +     struct dln2_response *rsp;
>> +     struct dln2_rx_context *rxc;
>> +     struct device *dev;
>> +     const int timeout = DLN2_USB_TIMEOUT * HZ / 1000;
>> +     struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
>> +
>
> Check the disconnected flag before incrementing the transfer count
> (while holding the device lock) here. Then decrement counter before
> returning and wake up an waiters if disconnected below.
>
> That is sufficient to implement wait-until-io-has-completed. Anything
> else you do below and in the helper functions is only to speed things
> up at disconnect (and can be done without locking the device).
>
>> +     rx_slot = alloc_rx_slot(rxs);
>> +     if (rx_slot < 0)
>> +             return rx_slot;
>> +
>> +     dev = &dln2->interface->dev;
>> +
>> +     ret = dln2_send_wait(dln2, handle, cmd, rx_slot, obuf, obuf_len);
>> +     if (ret < 0) {
>> +             free_rx_slot(dln2, rxs, rx_slot);
>
> goto out_free_rx_slot
>
>> +             dev_err(dev, "USB write failed: %d", ret);
>> +             return ret;
>> +     }
>> +
>> +     rxc = &rxs->slots[rx_slot];
>> +
>> +     ret = wait_for_completion_interruptible_timeout(&rxc->done, timeout);
>> +     if (ret <= 0) {
>> +             if (!ret)
>> +                     ret = -ETIMEDOUT;
>> +             goto out_free_rx_slot;
>> +     }
>> +
>> +     spin_lock_irqsave(&rxs->lock, flags);
>> +
>> +     if (!rxc->urb) {
>
> Just check the disconnected flag directly here. Locking not needed (see
> below).
>

I think we need the check here for the case when we cancel the
completion and no response has been received yet. In that case rx->urb
will be NULL (even if we remove the rx->urb = NULL statement in
dln2_stop).

>> +             ret = -ECONNRESET;
>
> -ENODEV

OK.

>
>> +             spin_unlock_irqrestore(&rxs->lock, flags);
>> +             goto out_free_rx_slot;
>> +     }
>> +
>> +     /* if we got here we know that the response header has been checked */
>> +     rsp = rxc->urb->transfer_buffer;
>> +
>> +     spin_unlock_irqrestore(&rxs->lock, flags);
>> +
>> +
>> +static void dln2_stop(struct dln2_dev *dln2)
>> +{
>> +     int i, j;
>> +
>> +     for (i = 0; i < DLN2_HANDLES; i++) {
>> +             struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[i];
>> +             unsigned long flags;
>> +
>> +             spin_lock_irqsave(&rxs->lock, flags);
>> +
>> +             /* fail further alloc_rx_slot calls */
>> +             rxs->disconnected = true;
>> +
>> +             /* cancel all response waiters */
>> +             for (j = 0; j < DLN2_MAX_RX_SLOTS; j++) {
>> +                     struct dln2_rx_context *rxc = &rxs->slots[j];
>> +
>> +                     if (rxc->connected) {
>> +                             rxc->urb = NULL;
>
> Don't overload the meaning of urb. Check the disconnected flag were
> needed.
>
> Also what would prevent a racing completion handler from setting
> rxc->urb again when you release the lock below?
>

That should not be an issue, in that case _dln2_transfer will complete
successfully. But you are right, we don't need to set rxc->urb to NULL
here.

>> +                             complete(&rxc->done);
>> +                     }
>> +             }
>> +             spin_unlock_irqrestore(&rxs->lock, flags);
>> +
>> +             /* wait for callers to release all rx_slots */
>> +             wait_event(rxs->wq, dln2_all_rx_slots_free(rxs));
>> +     }
>> +}
>> +
>> +static void dln2_disconnect(struct usb_interface *interface)
>> +{
>> +     struct dln2_dev *dln2 = usb_get_intfdata(interface);
>> +
>
> First set the disconnected flag directly here to prevent any new
> transfers from starting.
>
>> +     dln2_stop(dln2);
>
> Then do all the completions (to speed things up somewhat).
>
> Then wait for the transfer counter to reach 0.
>
>> +     mfd_remove_devices(&interface->dev);
>> +     dln2_free(dln2);
>> +}
>> +

As I mentioned above, I don't think we need the transfer counter, we
can rely on the slots bitmap. Yes, a counter is simpler but it also
requires adding a new waiting queue and a new lock.

<snip>

>> +     ret = dln2_hw_init(dln2);
>> +     if (ret < 0) {
>> +             dev_err(dev, "failed to initialize hardware\n");
>> +             goto out_cleanup;
>> +     }
>> +
>> +     ret = mfd_add_devices(dev, -1, dln2_devs, ARRAY_SIZE(dln2_devs),
>
> Use
>         busnum << 8 | devnum
>
> as id for now (as mentioned earlier).
>

Right, forgot about this, sorry.

Re: [PATCH v5 1/4] mfd: add support for Diolan DLN-2 devices

[Octavian Purdila]

On Wed, Sep 24, 2014 at 1:48 PM, Johan Hovold <johan@kernel.org> wrote:
> On Fri, Sep 19, 2014 at 11:22:42PM +0300, Octavian Purdila wrote:

<snip>

>> + * dln2_dev.mod_rx_slots and then the echo header field to index the
>> + * slots field and find the receive context for a particular
>> + * request.
>> + */
>> +struct dln2_mod_rx_slots {
>> +     /* RX slots bitmap */
>> +     unsigned long bmap;
>> +
>> +     /* used to wait for a free RX slot */
>> +     wait_queue_head_t wq;
>> +
>> +     /* used to wait for an RX operation to complete */
>> +     struct dln2_rx_context slots[DLN2_MAX_RX_SLOTS];
>> +
>> +     /* device has been disconnected */
>> +     bool disconnected;
>
> This belongs in the dln2_dev struct.
>
> I think you're overcomplicating the disconnect handling by intertwining
> it with your slots.
>
> Add a lock, an active-transfer counter, a disconnected flag, and a wait
> queue to struct dln2_dev.
>

I agree that disconnected is better suited in dln2_dev.

However, I don't think that we need the active-transfer counter and a
new wait queue. We can simply use the existing waiting queues and the
implicit alloc_rx_slot()/free_rx_slot() calls to see if we are still
waiting for I/O.

<snip>

>> +
>> +static int _dln2_transfer(struct dln2_dev *dln2, u16 handle, u16 cmd,
>> +                       const void *obuf, unsigned obuf_len,
>> +                       void *ibuf, unsigned *ibuf_len)
>> +{
>> +     int ret = 0;
>> +     u16 result;
>> +     int rx_slot;
>> +     unsigned long flags;
>> +     struct dln2_response *rsp;
>> +     struct dln2_rx_context *rxc;
>> +     struct device *dev;
>> +     const int timeout = DLN2_USB_TIMEOUT * HZ / 1000;
>> +     struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
>> +
>
> Check the disconnected flag before incrementing the transfer count
> (while holding the device lock) here. Then decrement counter before
> returning and wake up an waiters if disconnected below.
>
> That is sufficient to implement wait-until-io-has-completed. Anything
> else you do below and in the helper functions is only to speed things
> up at disconnect (and can be done without locking the device).
>
>> +     rx_slot = alloc_rx_slot(rxs);
>> +     if (rx_slot < 0)
>> +             return rx_slot;
>> +
>> +     dev = &dln2->interface->dev;
>> +
>> +     ret = dln2_send_wait(dln2, handle, cmd, rx_slot, obuf, obuf_len);
>> +     if (ret < 0) {
>> +             free_rx_slot(dln2, rxs, rx_slot);
>
> goto out_free_rx_slot
>
>> +             dev_err(dev, "USB write failed: %d", ret);
>> +             return ret;
>> +     }
>> +
>> +     rxc = &rxs->slots[rx_slot];
>> +
>> +     ret = wait_for_completion_interruptible_timeout(&rxc->done, timeout);
>> +     if (ret <= 0) {
>> +             if (!ret)
>> +                     ret = -ETIMEDOUT;
>> +             goto out_free_rx_slot;
>> +     }
>> +
>> +     spin_lock_irqsave(&rxs->lock, flags);
>> +
>> +     if (!rxc->urb) {
>
> Just check the disconnected flag directly here. Locking not needed (see
> below).
>

I think we need the check here for the case when we cancel the
completion and no response has been received yet. In that case rx->urb
will be NULL (even if we remove the rx->urb = NULL statement in
dln2_stop).

>> +             ret = -ECONNRESET;
>
> -ENODEV

OK.

>
>> +             spin_unlock_irqrestore(&rxs->lock, flags);
>> +             goto out_free_rx_slot;
>> +     }
>> +
>> +     /* if we got here we know that the response header has been checked */
>> +     rsp = rxc->urb->transfer_buffer;
>> +
>> +     spin_unlock_irqrestore(&rxs->lock, flags);
>> +
>> +
>> +static void dln2_stop(struct dln2_dev *dln2)
>> +{
>> +     int i, j;
>> +
>> +     for (i = 0; i < DLN2_HANDLES; i++) {
>> +             struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[i];
>> +             unsigned long flags;
>> +
>> +             spin_lock_irqsave(&rxs->lock, flags);
>> +
>> +             /* fail further alloc_rx_slot calls */
>> +             rxs->disconnected = true;
>> +
>> +             /* cancel all response waiters */
>> +             for (j = 0; j < DLN2_MAX_RX_SLOTS; j++) {
>> +                     struct dln2_rx_context *rxc = &rxs->slots[j];
>> +
>> +                     if (rxc->connected) {
>> +                             rxc->urb = NULL;
>
> Don't overload the meaning of urb. Check the disconnected flag were
> needed.
>
> Also what would prevent a racing completion handler from setting
> rxc->urb again when you release the lock below?
>

That should not be an issue, in that case _dln2_transfer will complete
successfully. But you are right, we don't need to set rxc->urb to NULL
here.

>> +                             complete(&rxc->done);
>> +                     }
>> +             }
>> +             spin_unlock_irqrestore(&rxs->lock, flags);
>> +
>> +             /* wait for callers to release all rx_slots */
>> +             wait_event(rxs->wq, dln2_all_rx_slots_free(rxs));
>> +     }
>> +}
>> +
>> +static void dln2_disconnect(struct usb_interface *interface)
>> +{
>> +     struct dln2_dev *dln2 = usb_get_intfdata(interface);
>> +
>
> First set the disconnected flag directly here to prevent any new
> transfers from starting.
>
>> +     dln2_stop(dln2);
>
> Then do all the completions (to speed things up somewhat).
>
> Then wait for the transfer counter to reach 0.
>
>> +     mfd_remove_devices(&interface->dev);
>> +     dln2_free(dln2);
>> +}
>> +

As I mentioned above, I don't think we need the transfer counter, we
can rely on the slots bitmap. Yes, a counter is simpler but it also
requires adding a new waiting queue and a new lock.

<snip>

>> +     ret = dln2_hw_init(dln2);
>> +     if (ret < 0) {
>> +             dev_err(dev, "failed to initialize hardware\n");
>> +             goto out_cleanup;
>> +     }
>> +
>> +     ret = mfd_add_devices(dev, -1, dln2_devs, ARRAY_SIZE(dln2_devs),
>
> Use
>         busnum << 8 | devnum
>
> as id for now (as mentioned earlier).
>

Right, forgot about this, sorry.

Re: [PATCH v5 1/4] mfd: add support for Diolan DLN-2 devices

[Johan Hovold]

On Wed, Sep 24, 2014 at 04:36:22PM +0300, Octavian Purdila wrote:
> On Wed, Sep 24, 2014 at 1:48 PM, Johan Hovold <johan@kernel.org> wrote:
> > On Fri, Sep 19, 2014 at 11:22:42PM +0300, Octavian Purdila wrote:
> 
> <snip>
> 
> >> + * dln2_dev.mod_rx_slots and then the echo header field to index the
> >> + * slots field and find the receive context for a particular
> >> + * request.
> >> + */
> >> +struct dln2_mod_rx_slots {
> >> +     /* RX slots bitmap */
> >> +     unsigned long bmap;
> >> +
> >> +     /* used to wait for a free RX slot */
> >> +     wait_queue_head_t wq;
> >> +
> >> +     /* used to wait for an RX operation to complete */
> >> +     struct dln2_rx_context slots[DLN2_MAX_RX_SLOTS];
> >> +
> >> +     /* device has been disconnected */
> >> +     bool disconnected;
> >
> > This belongs in the dln2_dev struct.
> >
> > I think you're overcomplicating the disconnect handling by intertwining
> > it with your slots.
> >
> > Add a lock, an active-transfer counter, a disconnected flag, and a wait
> > queue to struct dln2_dev.
> >
> 
> I agree that disconnected is better suited in dln2_dev.
> 
> However, I don't think that we need the active-transfer counter and a
> new wait queue. We can simply use the existing waiting queues and the
> implicit alloc_rx_slot()/free_rx_slot() calls to see if we are still
> waiting for I/O.

Just because you can reuse them doesn't mean it's a good idea. By
separating a generic disconnect solution from your custom slot
implementation we get something that is way easier to verify for
correctness and that could also be reused in other drivers.

> <snip>
> 
> >> +
> >> +static int _dln2_transfer(struct dln2_dev *dln2, u16 handle, u16 cmd,
> >> +                       const void *obuf, unsigned obuf_len,
> >> +                       void *ibuf, unsigned *ibuf_len)
> >> +{
> >> +     int ret = 0;
> >> +     u16 result;
> >> +     int rx_slot;
> >> +     unsigned long flags;
> >> +     struct dln2_response *rsp;
> >> +     struct dln2_rx_context *rxc;
> >> +     struct device *dev;
> >> +     const int timeout = DLN2_USB_TIMEOUT * HZ / 1000;
> >> +     struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
> >> +
> >
> > Check the disconnected flag before incrementing the transfer count
> > (while holding the device lock) here. Then decrement counter before
> > returning and wake up an waiters if disconnected below.
> >
> > That is sufficient to implement wait-until-io-has-completed. Anything
> > else you do below and in the helper functions is only to speed things
> > up at disconnect (and can be done without locking the device).
> >
> >> +     rx_slot = alloc_rx_slot(rxs);
> >> +     if (rx_slot < 0)
> >> +             return rx_slot;
> >> +
> >> +     dev = &dln2->interface->dev;
> >> +
> >> +     ret = dln2_send_wait(dln2, handle, cmd, rx_slot, obuf, obuf_len);
> >> +     if (ret < 0) {
> >> +             free_rx_slot(dln2, rxs, rx_slot);
> >
> > goto out_free_rx_slot
> >
> >> +             dev_err(dev, "USB write failed: %d", ret);
> >> +             return ret;
> >> +     }
> >> +
> >> +     rxc = &rxs->slots[rx_slot];
> >> +
> >> +     ret = wait_for_completion_interruptible_timeout(&rxc->done, timeout);
> >> +     if (ret <= 0) {
> >> +             if (!ret)
> >> +                     ret = -ETIMEDOUT;
> >> +             goto out_free_rx_slot;
> >> +     }
> >> +
> >> +     spin_lock_irqsave(&rxs->lock, flags);
> >> +
> >> +     if (!rxc->urb) {
> >
> > Just check the disconnected flag directly here. Locking not needed (see
> > below).
> >
> 
> I think we need the check here for the case when we cancel the
> completion and no response has been received yet. In that case rx->urb
> will be NULL (even if we remove the rx->urb = NULL statement in
> dln2_stop).

But the disconnect flag will also be set and makes it more obvious what
is going on.

[...]

> >> +static void dln2_disconnect(struct usb_interface *interface)
> >> +{
> >> +     struct dln2_dev *dln2 = usb_get_intfdata(interface);
> >> +
> >
> > First set the disconnected flag directly here to prevent any new
> > transfers from starting.
> >
> >> +     dln2_stop(dln2);
> >
> > Then do all the completions (to speed things up somewhat).
> >
> > Then wait for the transfer counter to reach 0.
> >
> >> +     mfd_remove_devices(&interface->dev);
> >> +     dln2_free(dln2);
> >> +}
> >> +
> 
> As I mentioned above, I don't think we need the transfer counter, we
> can rely on the slots bitmap. Yes, a counter is simpler but it also
> requires adding a new waiting queue and a new lock.

That's really not a big deal. See above.

Johan

Re: [PATCH v5 1/4] mfd: add support for Diolan DLN-2 devices

[Octavian Purdila]

On Wed, Sep 24, 2014 at 4:54 PM, Johan Hovold <johan@kernel.org> wrote:
> On Wed, Sep 24, 2014 at 04:36:22PM +0300, Octavian Purdila wrote:
>> On Wed, Sep 24, 2014 at 1:48 PM, Johan Hovold <johan@kernel.org> wrote:
>> > On Fri, Sep 19, 2014 at 11:22:42PM +0300, Octavian Purdila wrote:
>>
>> <snip>
>>
>> >> + * dln2_dev.mod_rx_slots and then the echo header field to index the
>> >> + * slots field and find the receive context for a particular
>> >> + * request.
>> >> + */
>> >> +struct dln2_mod_rx_slots {
>> >> +     /* RX slots bitmap */
>> >> +     unsigned long bmap;
>> >> +
>> >> +     /* used to wait for a free RX slot */
>> >> +     wait_queue_head_t wq;
>> >> +
>> >> +     /* used to wait for an RX operation to complete */
>> >> +     struct dln2_rx_context slots[DLN2_MAX_RX_SLOTS];
>> >> +
>> >> +     /* device has been disconnected */
>> >> +     bool disconnected;
>> >
>> > This belongs in the dln2_dev struct.
>> >
>> > I think you're overcomplicating the disconnect handling by intertwining
>> > it with your slots.
>> >
>> > Add a lock, an active-transfer counter, a disconnected flag, and a wait
>> > queue to struct dln2_dev.
>> >
>>
>> I agree that disconnected is better suited in dln2_dev.
>>
>> However, I don't think that we need the active-transfer counter and a
>> new wait queue. We can simply use the existing waiting queues and the
>> implicit alloc_rx_slot()/free_rx_slot() calls to see if we are still
>> waiting for I/O.
>
> Just because you can reuse them doesn't mean it's a good idea. By
> separating a generic disconnect solution from your custom slot
> implementation we get something that is way easier to verify for
> correctness and that could also be reused in other drivers.
>

Maybe I miss-understood what you are proposing, let me try to
summarize it to see if I got it right.

You are suggesting to add a counter, increment it in alloc_rx_slot(),
decrement it in free_rx_slot(). Then add a new waitqueue in dln2_dev
and in free_rx_slot() wake it up while in disconnect do a wait_event()
on it and check for the counter. Also, alloc_rx_slot() should fail if
the disconnect flag is set.

In this case we are still coupled to the slots implementation, in the
sense that you would need to understand the slots implementation to
understand how the disconnect works. We are also doing two wake-up
operations which I find redundant and which does not add much value in
clarity (since we still need to wake-up all completions for each
handle).

I do agree that using a counter instead of checking the bitmaps is
cleaner though.

Re: [PATCH v5 1/4] mfd: add support for Diolan DLN-2 devices

[Johan Hovold]

On Wed, Sep 24, 2014 at 05:54:15PM +0300, Octavian Purdila wrote:
> On Wed, Sep 24, 2014 at 4:54 PM, Johan Hovold <johan@kernel.org> wrote:
> > On Wed, Sep 24, 2014 at 04:36:22PM +0300, Octavian Purdila wrote:
> >> On Wed, Sep 24, 2014 at 1:48 PM, Johan Hovold <johan@kernel.org> wrote:
> >> > On Fri, Sep 19, 2014 at 11:22:42PM +0300, Octavian Purdila wrote:
> >>
> >> <snip>
> >>
> >> >> + * dln2_dev.mod_rx_slots and then the echo header field to index the
> >> >> + * slots field and find the receive context for a particular
> >> >> + * request.
> >> >> + */
> >> >> +struct dln2_mod_rx_slots {
> >> >> +     /* RX slots bitmap */
> >> >> +     unsigned long bmap;
> >> >> +
> >> >> +     /* used to wait for a free RX slot */
> >> >> +     wait_queue_head_t wq;
> >> >> +
> >> >> +     /* used to wait for an RX operation to complete */
> >> >> +     struct dln2_rx_context slots[DLN2_MAX_RX_SLOTS];
> >> >> +
> >> >> +     /* device has been disconnected */
> >> >> +     bool disconnected;
> >> >
> >> > This belongs in the dln2_dev struct.
> >> >
> >> > I think you're overcomplicating the disconnect handling by intertwining
> >> > it with your slots.
> >> >
> >> > Add a lock, an active-transfer counter, a disconnected flag, and a wait
> >> > queue to struct dln2_dev.
> >> >
> >>
> >> I agree that disconnected is better suited in dln2_dev.
> >>
> >> However, I don't think that we need the active-transfer counter and a
> >> new wait queue. We can simply use the existing waiting queues and the
> >> implicit alloc_rx_slot()/free_rx_slot() calls to see if we are still
> >> waiting for I/O.
> >
> > Just because you can reuse them doesn't mean it's a good idea. By
> > separating a generic disconnect solution from your custom slot
> > implementation we get something that is way easier to verify for
> > correctness and that could also be reused in other drivers.
> 
> Maybe I miss-understood what you are proposing, let me try to
> summarize it to see if I got it right.
> 
> You are suggesting to add a counter, increment it in alloc_rx_slot(),
> decrement it in free_rx_slot().

No increment it at the start of _dln2_transfer, and decrement it before
returning from that function.

> Then add a new waitqueue in dln2_dev
> and in free_rx_slot() wake it up while in disconnect do a wait_event()
> on it and check for the counter.

Where you also wake the disconnect (or wait-until-sent) wait queue.

> Also, alloc_rx_slot() should fail if
> the disconnect flag is set.

That is not required, but you can bail out early after alloc_rx_slot if
the disconnect flag is set (no locking).

> In this case we are still coupled to the slots implementation, in the
> sense that you would need to understand the slots implementation to
> understand how the disconnect works. We are also doing two wake-up
> operations which I find redundant and which does not add much value in
> clarity (since we still need to wake-up all completions for each
> handle).
>
> I do agree that using a counter instead of checking the bitmaps is
> cleaner though.

You only need to the wake up if disconnected is set when returning from
_dln2_transfer.

Sure, the optimisation bit -- to abort any ongoing transfer -- still
requires some insight into the slot implementation.

But this way everything disconnect related (correctness-wise) is
isolated to _dln2_transfer and dln2_disconnect.

Johan

Re: [PATCH v5 1/4] mfd: add support for Diolan DLN-2 devices

[Octavian Purdila]

On Wed, Sep 24, 2014 at 6:07 PM, Johan Hovold <johan@kernel.org> wrote:
> On Wed, Sep 24, 2014 at 05:54:15PM +0300, Octavian Purdila wrote:
>> On Wed, Sep 24, 2014 at 4:54 PM, Johan Hovold <johan@kernel.org> wrote:
>> > On Wed, Sep 24, 2014 at 04:36:22PM +0300, Octavian Purdila wrote:
>> >> On Wed, Sep 24, 2014 at 1:48 PM, Johan Hovold <johan@kernel.org> wrote:
>> >> > On Fri, Sep 19, 2014 at 11:22:42PM +0300, Octavian Purdila wrote:
>> >>
>> >> <snip>
>> >>
>> >> >> + * dln2_dev.mod_rx_slots and then the echo header field to index the
>> >> >> + * slots field and find the receive context for a particular
>> >> >> + * request.
>> >> >> + */
>> >> >> +struct dln2_mod_rx_slots {
>> >> >> +     /* RX slots bitmap */
>> >> >> +     unsigned long bmap;
>> >> >> +
>> >> >> +     /* used to wait for a free RX slot */
>> >> >> +     wait_queue_head_t wq;
>> >> >> +
>> >> >> +     /* used to wait for an RX operation to complete */
>> >> >> +     struct dln2_rx_context slots[DLN2_MAX_RX_SLOTS];
>> >> >> +
>> >> >> +     /* device has been disconnected */
>> >> >> +     bool disconnected;
>> >> >
>> >> > This belongs in the dln2_dev struct.
>> >> >
>> >> > I think you're overcomplicating the disconnect handling by intertwining
>> >> > it with your slots.
>> >> >
>> >> > Add a lock, an active-transfer counter, a disconnected flag, and a wait
>> >> > queue to struct dln2_dev.
>> >> >
>> >>
>> >> I agree that disconnected is better suited in dln2_dev.
>> >>
>> >> However, I don't think that we need the active-transfer counter and a
>> >> new wait queue. We can simply use the existing waiting queues and the
>> >> implicit alloc_rx_slot()/free_rx_slot() calls to see if we are still
>> >> waiting for I/O.
>> >
>> > Just because you can reuse them doesn't mean it's a good idea. By
>> > separating a generic disconnect solution from your custom slot
>> > implementation we get something that is way easier to verify for
>> > correctness and that could also be reused in other drivers.
>>
>> Maybe I miss-understood what you are proposing, let me try to
>> summarize it to see if I got it right.
>>
>> You are suggesting to add a counter, increment it in alloc_rx_slot(),
>> decrement it in free_rx_slot().
>
> No increment it at the start of _dln2_transfer, and decrement it before
> returning from that function.
>
>> Then add a new waitqueue in dln2_dev
>> and in free_rx_slot() wake it up while in disconnect do a wait_event()
>> on it and check for the counter.
>
> Where you also wake the disconnect (or wait-until-sent) wait queue.
>
>> Also, alloc_rx_slot() should fail if
>> the disconnect flag is set.
>
> That is not required, but you can bail out early after alloc_rx_slot if
> the disconnect flag is set (no locking).
>
>> In this case we are still coupled to the slots implementation, in the
>> sense that you would need to understand the slots implementation to
>> understand how the disconnect works. We are also doing two wake-up
>> operations which I find redundant and which does not add much value in
>> clarity (since we still need to wake-up all completions for each
>> handle).
>>
>> I do agree that using a counter instead of checking the bitmaps is
>> cleaner though.
>
> You only need to the wake up if disconnected is set when returning from
> _dln2_transfer.
>
> Sure, the optimisation bit -- to abort any ongoing transfer -- still
> requires some insight into the slot implementation.
>
> But this way everything disconnect related (correctness-wise) is
> isolated to _dln2_transfer and dln2_disconnect.
>

OK, I see what you mean now. I'll give it a try and will follow up
with a new patch set.

Oh, and thanks for yet another review, it has been very educational to
me just like the rest  :)

Re: [PATCH v5 1/4] mfd: add support for Diolan DLN-2 devices

[Octavian Purdila]

On Wed, Sep 24, 2014 at 6:22 PM, Octavian Purdila
<octavian.purdila@intel.com> wrote:
> On Wed, Sep 24, 2014 at 6:07 PM, Johan Hovold <johan@kernel.org> wrote:
>> On Wed, Sep 24, 2014 at 05:54:15PM +0300, Octavian Purdila wrote:
>>> On Wed, Sep 24, 2014 at 4:54 PM, Johan Hovold <johan@kernel.org> wrote:
>>> > On Wed, Sep 24, 2014 at 04:36:22PM +0300, Octavian Purdila wrote:
>>> >> On Wed, Sep 24, 2014 at 1:48 PM, Johan Hovold <johan@kernel.org> wrote:
>>> >> > On Fri, Sep 19, 2014 at 11:22:42PM +0300, Octavian Purdila wrote:
>>> >>
>>> >> <snip>
>>> >>
>>> >> >> + * dln2_dev.mod_rx_slots and then the echo header field to index the
>>> >> >> + * slots field and find the receive context for a particular
>>> >> >> + * request.
>>> >> >> + */
>>> >> >> +struct dln2_mod_rx_slots {
>>> >> >> +     /* RX slots bitmap */
>>> >> >> +     unsigned long bmap;
>>> >> >> +
>>> >> >> +     /* used to wait for a free RX slot */
>>> >> >> +     wait_queue_head_t wq;
>>> >> >> +
>>> >> >> +     /* used to wait for an RX operation to complete */
>>> >> >> +     struct dln2_rx_context slots[DLN2_MAX_RX_SLOTS];
>>> >> >> +
>>> >> >> +     /* device has been disconnected */
>>> >> >> +     bool disconnected;
>>> >> >
>>> >> > This belongs in the dln2_dev struct.
>>> >> >
>>> >> > I think you're overcomplicating the disconnect handling by intertwining
>>> >> > it with your slots.
>>> >> >
>>> >> > Add a lock, an active-transfer counter, a disconnected flag, and a wait
>>> >> > queue to struct dln2_dev.
>>> >> >
>>> >>
>>> >> I agree that disconnected is better suited in dln2_dev.
>>> >>
>>> >> However, I don't think that we need the active-transfer counter and a
>>> >> new wait queue. We can simply use the existing waiting queues and the
>>> >> implicit alloc_rx_slot()/free_rx_slot() calls to see if we are still
>>> >> waiting for I/O.
>>> >
>>> > Just because you can reuse them doesn't mean it's a good idea. By
>>> > separating a generic disconnect solution from your custom slot
>>> > implementation we get something that is way easier to verify for
>>> > correctness and that could also be reused in other drivers.
>>>
>>> Maybe I miss-understood what you are proposing, let me try to
>>> summarize it to see if I got it right.
>>>
>>> You are suggesting to add a counter, increment it in alloc_rx_slot(),
>>> decrement it in free_rx_slot().
>>
>> No increment it at the start of _dln2_transfer, and decrement it before
>> returning from that function.
>>
>>> Then add a new waitqueue in dln2_dev
>>> and in free_rx_slot() wake it up while in disconnect do a wait_event()
>>> on it and check for the counter.
>>
>> Where you also wake the disconnect (or wait-until-sent) wait queue.
>>
>>> Also, alloc_rx_slot() should fail if
>>> the disconnect flag is set.
>>
>> That is not required, but you can bail out early after alloc_rx_slot if
>> the disconnect flag is set (no locking).
>>
>>> In this case we are still coupled to the slots implementation, in the
>>> sense that you would need to understand the slots implementation to
>>> understand how the disconnect works. We are also doing two wake-up
>>> operations which I find redundant and which does not add much value in
>>> clarity (since we still need to wake-up all completions for each
>>> handle).
>>>
>>> I do agree that using a counter instead of checking the bitmaps is
>>> cleaner though.
>>
>> You only need to the wake up if disconnected is set when returning from
>> _dln2_transfer.
>>
>> Sure, the optimisation bit -- to abort any ongoing transfer -- still
>> requires some insight into the slot implementation.
>>
>> But this way everything disconnect related (correctness-wise) is
>> isolated to _dln2_transfer and dln2_disconnect.
>>
>
> OK, I see what you mean now. I'll give it a try and will follow up
> with a new patch set.
>

Johan, I think we don't really need the spinlock, the disconnect flag
and an atomic counter should work. Do you see any issues with that?

Re: [PATCH v5 1/4] mfd: add support for Diolan DLN-2 devices

[Johan Hovold]

On Thu, Sep 25, 2014 at 01:25:24PM +0300, Octavian Purdila wrote:

> Johan, I think we don't really need the spinlock, the disconnect flag
> and an atomic counter should work. Do you see any issues with that?

No, you need to test and increment atomically so the lock is needed.

Consider what could happen if you get a disconnect after testing but
before incrementing.

Johan

Re: [PATCH v5 1/4] mfd: add support for Diolan DLN-2 devices

[Octavian Purdila]

On Thu, Sep 25, 2014 at 1:30 PM, Johan Hovold <johan@kernel.org> wrote:
> On Thu, Sep 25, 2014 at 01:25:24PM +0300, Octavian Purdila wrote:
>
>> Johan, I think we don't really need the spinlock, the disconnect flag
>> and an atomic counter should work. Do you see any issues with that?
>
> No, you need to test and increment atomically so the lock is needed.
>
> Consider what could happen if you get a disconnect after testing but
> before incrementing.
>

I am still not seeing the problem. We would continue with the
increment, we will try to send which will fail and go on the error
path where we will decrement and wake_up. What am I missing?

Re: [PATCH v5 1/4] mfd: add support for Diolan DLN-2 devices

[Johan Hovold]

On Thu, Sep 25, 2014 at 01:41:16PM +0300, Octavian Purdila wrote:
> On Thu, Sep 25, 2014 at 1:30 PM, Johan Hovold <johan@kernel.org> wrote:
> > On Thu, Sep 25, 2014 at 01:25:24PM +0300, Octavian Purdila wrote:
> >
> >> Johan, I think we don't really need the spinlock, the disconnect flag
> >> and an atomic counter should work. Do you see any issues with that?
> >
> > No, you need to test and increment atomically so the lock is needed.
> >
> > Consider what could happen if you get a disconnect after testing but
> > before incrementing.
> 
> I am still not seeing the problem. We would continue with the
> increment, we will try to send which will fail and go on the error
> path where we will decrement and wake_up. What am I missing?

The whole point of the counter and flag is to make sure that no
transfers are started after the flag is set. If you remove the lock you
cannot guarantee that.

Disconnect sets the flag (after you test it in transfer() but before
incrementing the counter), checks the counter which is 0 and proceeds
with deregistration and deallocation. Then transfer() gets to run...

Johan