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* [RFC net-next] net: Z-Wave driver prototype
@ 2019-01-20 18:33 Andreas Färber
  2019-01-20 18:56 ` Randy Dunlap
  0 siblings, 1 reply; 3+ messages in thread
From: Andreas Färber @ 2019-01-20 18:33 UTC (permalink / raw)
  To: linux-lpwan, linux-wpan
  Cc: Alexander Aring, Stefan Schmidt, netdev, linux-kernel,
	Andreas Färber, TL Lim, David S. Miller

Inspired from my LoRa and FSK driver project, I've hacked together a PoC
for an in-kernel Z-Wave driver. Tested with Pine64 Z-Wave module.

The by now SiLabs ZM5304 module exposes a UART interface that this
serdev driver can be attached to, using Device Tree.

There didn't appear to be any schematics for the Pine64 Z-Wave adapter,
so the reset GPIO handling is still missing.

Helpers are implemented for dealing with command, response and respective
checksum-based acknowledgements.

While by now there is extensive public documentation on Command Classes
for individual types of Z-Wave devices, I still couldn't find any proper
documentation of the UART protocol below and relied on a former tutorial
by Henrik Leidecker Jørgensen documenting commands for device discovery.

Tested as external kernel module, so Kconfig/Makefile integration missing.

Some ideas where to take this from here:
1) Try to expose this as a net device and leave node communication to
   userspace via sockets (command/response as skb?) or other means.
2) Make this its own, e.g., drivers/zwave/ subsystem as bus and create
   individual drivers (iio, gpio, led, etc.) for the various node types.
   Optionally, implement a zwave-dev driver for generic userspace access
   to one particular node, similar to spidev.

Note: Z-Wave is based on GFSK modulation, so someone with a lot of time
might implement it based on the FSK drivers being created alongside LoRa.
That speaks against relying on the serial protocol, and it would not work
with any tty based userspace applications.

Cc: TL Lim <tllim@pine64.org>
Signed-off-by: Andreas Färber <afaerber@suse.de>
---
 drivers/net/zwave/Makefile |   1 +
 drivers/net/zwave/zwave.c  | 236 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 237 insertions(+)
 create mode 100644 drivers/net/zwave/Makefile
 create mode 100644 drivers/net/zwave/zwave.c

diff --git a/drivers/net/zwave/Makefile b/drivers/net/zwave/Makefile
new file mode 100644
index 000000000000..1a4171308c79
--- /dev/null
+++ b/drivers/net/zwave/Makefile
@@ -0,0 +1 @@
+obj-m += zwave.o
diff --git a/drivers/net/zwave/zwave.c b/drivers/net/zwave/zwave.c
new file mode 100644
index 000000000000..8ac680bbb969
--- /dev/null
+++ b/drivers/net/zwave/zwave.c
@@ -0,0 +1,236 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Z-Wave
+ *
+ * Copyright (c) 2019 Andreas Färber
+ */
+
+#include <linux/bitops.h>
+#include <linux/completion.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/rculist.h>
+#include <linux/serdev.h>
+
+struct zwave_msg_dispatcher {
+	struct list_head list;
+	u8 id;
+	void (*dispatch)(const u8 *data, u8 len, struct zwave_msg_dispatcher *d);
+};
+
+struct zwave_device {
+	struct serdev_device *serdev;
+
+	struct completion ack_comp;
+	struct list_head msg_dispatchers;
+
+	struct zwave_msg_dispatcher node_list_disp;
+};
+
+static void zwave_add_dispatcher(struct zwave_device *zdev,
+	struct zwave_msg_dispatcher *entry)
+{
+	list_add_tail_rcu(&entry->list, &zdev->msg_dispatchers);
+}
+
+static void zwave_remove_dispatcher(struct zwave_device *zdev,
+	struct zwave_msg_dispatcher *entry)
+{
+	list_del_rcu(&entry->list);
+}
+
+static u8 zwave_msg_checksum_first(const u8 first, const u8 *data, int len)
+{
+	u8 chksum;
+	int i;
+
+	chksum = first;
+	for (i = 0; i < len; i++) {
+		chksum ^= data[i];
+	}
+	return ~chksum;
+}
+
+static u8 zwave_msg_checksum(const u8 *data, int len)
+{
+	return zwave_msg_checksum_first(data[0], data + 1, len - 1);
+}
+
+static int zwave_send_msg(struct zwave_device *zdev, const u8 *data, int data_len,
+	unsigned long timeout)
+{
+	u8 chksum;
+	u8 buf[2];
+	int ret;
+
+	reinit_completion(&zdev->ack_comp);
+
+	buf[0] = 0x01;
+	buf[1] = data_len + 1;
+
+	chksum = zwave_msg_checksum_first(buf[1], data, data_len);
+	dev_dbg(&zdev->serdev->dev, "checksum: 0x%02x\n", (unsigned int)chksum);
+
+	ret = serdev_device_write(zdev->serdev, buf, 2, timeout);
+	if (ret < 0)
+		return ret;
+	if (ret > 0 && ret < 2)
+		return -EIO;
+
+	ret = serdev_device_write(zdev->serdev, data, data_len, timeout);
+	if (ret < 0)
+		return ret;
+	if (ret > 0 && ret < data_len)
+		return -EIO;
+
+	ret = serdev_device_write(zdev->serdev, &chksum, 1, timeout);
+	if (ret < 0)
+		return ret;
+
+	timeout = wait_for_completion_timeout(&zdev->ack_comp, timeout);
+	if (!timeout)
+		return -ETIMEDOUT;
+
+	return 0;
+}
+
+static void zwave_node_list_report(const u8 *data, u8 len,
+	struct zwave_msg_dispatcher *d)
+{
+	struct zwave_device *zdev = container_of(d, struct zwave_device, node_list_disp);
+	struct device *dev = &zdev->serdev->dev;
+	int i, j;
+
+	if (len != 36) {
+		dev_err(dev, "node list report unexpected length (%u)\n", (unsigned int)len);
+		return;
+	};
+
+	dev_info(dev, "node list report\n");
+	for (i = 0; i < data[4]; i++) {
+		u8 tmp = data[5 + i];
+		for (j = 0; j < 8; j++) {
+			if (tmp & BIT(j))
+				dev_info(dev, "node list data %u: node id %u\n", i + 1, i * 8 + j + 1);
+		}
+	}
+}
+
+static int zwave_receive_buf(struct serdev_device *sdev, const u8 *data, size_t count)
+{
+	struct zwave_device *zdev = serdev_device_get_drvdata(sdev);
+	struct zwave_msg_dispatcher *e;
+	u8 buf[1] = { 0x06 };
+	u8 msglen;
+	u8 chksum;
+
+	dev_dbg(&sdev->dev, "Receive (%zu)\n", count);
+
+	if (data[0] == 0x06) {
+		dev_info(&sdev->dev, "ACK received\n");
+		complete(&zdev->ack_comp);
+		return 1;
+	} else {
+		if (count < 2)
+			return 0;
+		msglen = data[1];
+		if (count < 2 + msglen) {
+			dev_dbg(&sdev->dev, "%s: received %zu, expecting %u\n", __func__, count, 2 + (unsigned int)msglen);
+			return 0;
+		}
+		print_hex_dump_bytes("received: ", DUMP_PREFIX_OFFSET, data, 2 + msglen);
+		if (msglen > 0) {
+			chksum = zwave_msg_checksum(data + 1, msglen);
+			if (data[1 + msglen] == chksum) {
+				dev_info(&sdev->dev, "sending ACK\n");
+				serdev_device_write_buf(sdev, buf, 1);
+			} else {
+				dev_warn(&sdev->dev, "checksum mismatch\n");
+				return 2 + msglen;
+			}
+		}
+		list_for_each_entry(e, &zdev->msg_dispatchers, list) {
+			if (msglen > 2 && e->id == data[3])
+				e->dispatch(data + 2, msglen ? msglen - 1 : 0, e);
+		}
+		return 2 + msglen;
+	}
+}
+
+static const struct serdev_device_ops zwave_serdev_client_ops = {
+	.receive_buf = zwave_receive_buf,
+	.write_wakeup = serdev_device_write_wakeup,
+};
+
+static int zwave_probe(struct serdev_device *sdev)
+{
+	struct zwave_device *zdev;
+	int ret;
+	const u8 msg[] = { 0x00, 0x02 };
+	//const u8 msg[] = { 0x00, 0x41, 1 };
+
+	dev_dbg(&sdev->dev, "Probing");
+
+	zdev = devm_kzalloc(&sdev->dev, sizeof(*zdev), GFP_KERNEL);
+	if (!zdev)
+		return -ENOMEM;
+
+	zdev->serdev = sdev;
+	init_completion(&zdev->ack_comp);
+	INIT_LIST_HEAD(&zdev->msg_dispatchers);
+	serdev_device_set_drvdata(sdev, zdev);
+
+	ret = serdev_device_open(sdev);
+	if (ret) {
+		dev_err(&sdev->dev, "Failed to open (%d)\n", ret);
+		return ret;
+	}
+
+	serdev_device_set_baudrate(sdev, 115200);
+	serdev_device_set_flow_control(sdev, false);
+	serdev_device_set_client_ops(sdev, &zwave_serdev_client_ops);
+
+	zdev->node_list_disp.id = 0x02;
+	zdev->node_list_disp.dispatch = zwave_node_list_report;
+	zwave_add_dispatcher(zdev, &zdev->node_list_disp);
+
+	ret = zwave_send_msg(zdev, msg, sizeof(msg), HZ);
+	if (ret) {
+		dev_warn(&sdev->dev, "Failed to send (%d)\n", ret);
+	}
+
+	dev_dbg(&sdev->dev, "Done.\n");
+
+	return 0;
+}
+
+static void zwave_remove(struct serdev_device *sdev)
+{
+	struct zwave_device *zdev = serdev_device_get_drvdata(sdev);
+
+	serdev_device_close(sdev);
+
+	zwave_remove_dispatcher(zdev, &zdev->node_list_disp);
+
+	dev_dbg(&sdev->dev, "Removed\n");
+}
+
+static const struct of_device_id zwave_of_match[] = {
+	{ .compatible = "zwave,zwave" }, /* XXX */
+	{}
+};
+MODULE_DEVICE_TABLE(of, zwave_of_match);
+
+static struct serdev_device_driver zwave_serdev_driver = {
+	.probe = zwave_probe,
+	.remove = zwave_remove,
+	.driver = {
+		.name = "zwave",
+		.of_match_table = zwave_of_match,
+	},
+};
+module_serdev_device_driver(zwave_serdev_driver);
+
+MODULE_DESCRIPTION("Z-Wave serdev driver");
+MODULE_AUTHOR("Andreas Färber <afaerber@suse.de>");
+MODULE_LICENSE("GPL");
-- 
2.16.4

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [RFC net-next] net: Z-Wave driver prototype
  2019-01-20 18:33 [RFC net-next] net: Z-Wave driver prototype Andreas Färber
@ 2019-01-20 18:56 ` Randy Dunlap
  2019-01-20 20:26   ` Andreas Färber
  0 siblings, 1 reply; 3+ messages in thread
From: Randy Dunlap @ 2019-01-20 18:56 UTC (permalink / raw)
  To: Andreas Färber, linux-lpwan, linux-wpan
  Cc: Alexander Aring, Stefan Schmidt, netdev, linux-kernel, TL Lim,
	David S. Miller

On 1/20/19 10:33 AM, Andreas Färber wrote:
> diff --git a/drivers/net/zwave/Makefile b/drivers/net/zwave/Makefile
> new file mode 100644
> index 000000000000..1a4171308c79
> --- /dev/null
> +++ b/drivers/net/zwave/Makefile
> @@ -0,0 +1 @@
> +obj-m += zwave.o


Hi,

This will need a Kconfig file and a symbol so that the Makefile
will not always build the zwave module.

thanks,
-- 
~Randy

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [RFC net-next] net: Z-Wave driver prototype
  2019-01-20 18:56 ` Randy Dunlap
@ 2019-01-20 20:26   ` Andreas Färber
  0 siblings, 0 replies; 3+ messages in thread
From: Andreas Färber @ 2019-01-20 20:26 UTC (permalink / raw)
  To: Randy Dunlap
  Cc: linux-lpwan, linux-wpan, Alexander Aring, Stefan Schmidt, netdev,
	linux-kernel, David S. Miller

Hi,

Am 20.01.19 um 19:56 schrieb Randy Dunlap:
> On 1/20/19 10:33 AM, Andreas Färber wrote:
>> Tested as external kernel module, so Kconfig/Makefile integration missing.
[...]
>> diff --git a/drivers/net/zwave/Makefile b/drivers/net/zwave/Makefile
>> new file mode 100644
>> index 000000000000..1a4171308c79
>> --- /dev/null
>> +++ b/drivers/net/zwave/Makefile
>> @@ -0,0 +1 @@
>> +obj-m += zwave.o
> 
> This will need a Kconfig file and a symbol so that the Makefile
> will not always build the zwave module.

Well, as I noted in the commit message you cut off, this Makefile is not
included from drivers/net/. So it should actually not get built at all,
unless you build it explicitly as module:

$ make -C /lib/modules/`uname -r`/build M=$PWD/drivers/net/zwave

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/kbuild/modules.txt?id=HEAD

This RFC is nowhere near merging, so there's no point in bike-shedding
about Kconfig help texts. The Kconfig/Makefile integration depends on
the alternatives outlined in the commit message of what to make of this.
Right now it does not expose any netdev nor any other useful interfaces,
merely demonstrating that via serdev it could be handled in the kernel.

The big context here is RF ASICs vs. SDR and the layering of PHY and MAC
implementations and their user-facing (socket) interfaces. Cf. slide 24:
https://events.linuxfoundation.org/wp-content/uploads/2017/12/ELCE2018_LoRa_final_Andreas-Farber.pdf
(Z-Wave was marked in orange as not-entirely-open protocol over FSK.)

I had this Z-Wave module lying around, so I gave it a quick shot to get
a feeling for the protocol in comparison. If no one finds the RFC useful
then it can die as quickly as it came to life. :)

Cheers,
Andreas

-- 
SUSE Linux GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)

^ permalink raw reply	[flat|nested] 3+ messages in thread

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2019-01-20 18:33 [RFC net-next] net: Z-Wave driver prototype Andreas Färber
2019-01-20 18:56 ` Randy Dunlap
2019-01-20 20:26   ` Andreas Färber

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