Date:	Thu, 10 Mar 2016 02:29:06 +0000
From:	Alexey Klimov <klimov.linux@...il.com>
To:	linux-watchdog@...r.kernel.org
Cc:	linux-usb@...r.kernel.org, wim@...ana.be, linux@...ck-us.net,
	linux-kernel@...r.kernel.org, yury.norov@...il.com,
	klimov.linux@...il.com
Subject: [PATCH] watchdog: add driver for StreamLabs USB watchdog device

This patch creates new driver that supports StreamLabs usb watchdog
device. This device plugs into 9-pin usb header and connects to
reset pin and reset button on common PC.

USB commands used to communicate with device were reverse
engineered using usbmon.

Signed-off-by: Alexey Klimov <klimov.linux@...il.com>
---
 drivers/watchdog/Kconfig          |  15 ++
 drivers/watchdog/Makefile         |   1 +
 drivers/watchdog/streamlabs_wdt.c | 370 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 386 insertions(+)
 create mode 100644 drivers/watchdog/streamlabs_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 80825a7..95d8f72 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1705,4 +1705,19 @@ config USBPCWATCHDOG
 
 	  Most people will say N.
 
+config USB_STREAMLABS_WATCHDOG
+	tristate "StreamLabs USB watchdog driver"
+	depends on USB
+	---help---
+	  This is the driver for the USB Watchdog dongle from StreamLabs.
+	  If you correctly connect reset pins to motherboard Reset pin and
+	  to Reset button then this device will simply watch your kernel to make
+	  sure it doesn't freeze, and if it does, it reboots your computer
+	  after a certain amount of time.
+
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called streamlabs_wdt.
+
+	  Most people will say N. Say yes or M if you want to use such usb device.
 endif # WATCHDOG
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index f6a6a38..d54fd31 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_WDTPCI) += wdt_pci.o
 
 # USB-based Watchdog Cards
 obj-$(CONFIG_USBPCWATCHDOG) += pcwd_usb.o
+obj-$(CONFIG_USB_STREAMLABS_WATCHDOG) += streamlabs_wdt.o
 
 # ALPHA Architecture
 
diff --git a/drivers/watchdog/streamlabs_wdt.c b/drivers/watchdog/streamlabs_wdt.c
new file mode 100644
index 0000000..031dbc35
--- /dev/null
+++ b/drivers/watchdog/streamlabs_wdt.c
@@ -0,0 +1,370 @@
+/*
+ * StreamLabs USB Watchdog driver
+ *
+ * Copyright (c) 2016 Alexey Klimov <klimov.linux@...il.com>
+ *
+ * This program is free software; you may redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+#include <linux/watchdog.h>
+
+/*
+ * USB Watchdog device from Streamlabs
+ * http://www.stream-labs.com/products/devices/watchdog/
+ *
+ * USB commands have been reverse engineered using usbmon.
+ */
+
+#define DRIVER_AUTHOR "Alexey Klimov <klimov.linux@...il.com>"
+#define DRIVER_DESC "StreamLabs USB watchdog driver"
+#define DRIVER_NAME "usb_streamlabs_wdt"
+
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+#define USB_STREAMLABS_WATCHDOG_VENDOR	0x13c0
+#define USB_STREAMLABS_WATCHDOG_PRODUCT	0x0011
+
+/* one buffer is used for communication, however transmitted message is only
+ * 32 bytes long */
+#define BUFFER_TRANSFER_LENGTH	32
+#define BUFFER_LENGTH		64
+#define USB_TIMEOUT		350
+
+#define STREAMLABS_CMD_START	0
+#define STREAMLABS_CMD_STOP	1
+
+#define STREAMLABS_WDT_MIN_TIMEOUT	1
+#define STREAMLABS_WDT_MAX_TIMEOUT	46
+
+struct streamlabs_wdt {
+	struct watchdog_device wdt_dev;
+	struct usb_device *usbdev;
+	struct usb_interface *intf;
+
+	struct kref kref;
+	struct mutex lock;
+	u8 *buffer;
+};
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+
+static int usb_streamlabs_wdt_validate_response(u8 *buf)
+{
+	/* If watchdog device understood the command it will acknowledge
+	 * with values 1,2,3,4 at indexes 10, 11, 12, 13 in response message.
+	 */
+	if (buf[10] != 1 || buf[11] != 2 || buf[12] != 3 || buf[13] != 4)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int usb_streamlabs_wdt_command(struct watchdog_device *wdt_dev, int cmd)
+{
+	struct streamlabs_wdt *streamlabs_wdt = watchdog_get_drvdata(wdt_dev);
+	int retval;
+	int size;
+	unsigned long timeout_msec;
+	int retry_counter = 10;		/* how many times to re-send stop cmd */
+
+	mutex_lock(&streamlabs_wdt->lock);
+
+	timeout_msec = wdt_dev->timeout * MSEC_PER_SEC;
+
+	/* Prepare message that will be sent to device.
+	 * This buffer is allocated by kzalloc(). Only initialize required
+	 * fields.
+	 */
+	if (cmd == STREAMLABS_CMD_START) {
+		streamlabs_wdt->buffer[0] = 0xcc;
+		streamlabs_wdt->buffer[1] = 0xaa;
+	} else {	/* assume stop command if it's not start */
+		streamlabs_wdt->buffer[0] = 0xff;
+		streamlabs_wdt->buffer[1] = 0xbb;
+	}
+
+	streamlabs_wdt->buffer[3] = 0x80;
+
+	streamlabs_wdt->buffer[6] = (timeout_msec & 0xff) << 8;
+	streamlabs_wdt->buffer[7] = (timeout_msec & 0xff00) >> 8;
+retry:
+	streamlabs_wdt->buffer[10] = 0x00;
+	streamlabs_wdt->buffer[11] = 0x00;
+	streamlabs_wdt->buffer[12] = 0x00;
+	streamlabs_wdt->buffer[13] = 0x00;
+
+	/* send command to watchdog */
+	retval = usb_interrupt_msg(streamlabs_wdt->usbdev,
+				usb_sndintpipe(streamlabs_wdt->usbdev, 0x02),
+				streamlabs_wdt->buffer, BUFFER_TRANSFER_LENGTH,
+				&size, USB_TIMEOUT);
+
+	if (retval || size != BUFFER_TRANSFER_LENGTH) {
+		dev_err(&streamlabs_wdt->intf->dev,
+			"error %i when submitting interrupt msg\n", retval);
+		retval = -EIO;
+		goto out;
+	}
+
+	/* and read response from watchdog */
+	retval = usb_interrupt_msg(streamlabs_wdt->usbdev,
+				usb_rcvintpipe(streamlabs_wdt->usbdev, 0x81),
+				streamlabs_wdt->buffer, BUFFER_LENGTH,
+				&size, USB_TIMEOUT);
+
+	if (retval || size != BUFFER_LENGTH) {
+		dev_err(&streamlabs_wdt->intf->dev,
+			"error %i when receiving interrupt msg\n", retval);
+		retval = -EIO;
+		goto out;
+	}
+
+	/* check if watchdog actually acked/recognized command */
+	retval = usb_streamlabs_wdt_validate_response(streamlabs_wdt->buffer);
+	if (retval) {
+		dev_err(&streamlabs_wdt->intf->dev,
+					"watchdog didn't ACK command!\n");
+		goto out;
+	}
+
+	/* Transition from enabled to disabled state in this device
+	 * doesn't happen immediately. Usually, 2 or 3 (sometimes even 4) stop
+	 * commands should be sent until watchdog answers 'I'm stopped!'.
+	 * Retry stop command if watchdog fails to answer correctly
+	 * about its state. After 10 attempts, report error and return -EIO.
+	 */
+	if (cmd == STREAMLABS_CMD_STOP) {
+		if (--retry_counter <= 0) {
+			dev_err(&streamlabs_wdt->intf->dev,
+				"failed to stop watchdog after 9 attempts!\n");
+			retval = -EIO;
+			goto out;
+		}
+		/*
+		 * Check if watchdog actually changed state to disabled.
+		 * If watchdog is still enabled then reset message and retry
+		 * stop command.
+		 */
+		if (streamlabs_wdt->buffer[0] != 0xff ||
+					streamlabs_wdt->buffer[1] != 0xbb) {
+			streamlabs_wdt->buffer[0] = 0xff;
+			streamlabs_wdt->buffer[1] = 0xbb;
+			goto retry;
+		}
+	}
+
+out:
+	mutex_unlock(&streamlabs_wdt->lock);
+	return retval;
+}
+
+static int usb_streamlabs_wdt_start(struct watchdog_device *wdt_dev)
+{
+	return usb_streamlabs_wdt_command(wdt_dev, STREAMLABS_CMD_START);
+}
+
+static int usb_streamlabs_wdt_stop(struct watchdog_device *wdt_dev)
+{
+	return usb_streamlabs_wdt_command(wdt_dev, STREAMLABS_CMD_STOP);
+}
+
+static int usb_streamlabs_wdt_settimeout(struct watchdog_device *wdt_dev,
+				unsigned int timeout)
+{
+	struct streamlabs_wdt *streamlabs_wdt = watchdog_get_drvdata(wdt_dev);
+
+	mutex_lock(&streamlabs_wdt->lock);
+	wdt_dev->timeout = timeout;
+	mutex_unlock(&streamlabs_wdt->lock);
+
+	return 0;
+}
+
+static void usb_streamlabs_wdt_release_resources(struct kref *kref)
+{
+	struct streamlabs_wdt *streamlabs_wdt =
+			container_of(kref, struct streamlabs_wdt, kref);
+
+	mutex_destroy(&streamlabs_wdt->lock);
+	kfree(streamlabs_wdt->buffer);
+	kfree(streamlabs_wdt);
+}
+
+static void usb_streamlabs_wdt_ref(struct watchdog_device *wdt_dev)
+{
+	struct streamlabs_wdt *streamlabs_wdt = watchdog_get_drvdata(wdt_dev);
+
+	kref_get(&streamlabs_wdt->kref);
+}
+
+static void usb_streamlabs_wdt_unref(struct watchdog_device *wdt_dev)
+{
+	struct streamlabs_wdt *streamlabs_wdt = watchdog_get_drvdata(wdt_dev);
+
+	kref_put(&streamlabs_wdt->kref, usb_streamlabs_wdt_release_resources);
+}
+
+static const struct watchdog_info streamlabs_wdt_ident = {
+	.options	= (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING),
+	.identity	= DRIVER_NAME,
+};
+
+static struct watchdog_ops usb_streamlabs_wdt_ops = {
+	.owner	= THIS_MODULE,
+	.start	= usb_streamlabs_wdt_start,
+	.stop	= usb_streamlabs_wdt_stop,
+	.set_timeout	= usb_streamlabs_wdt_settimeout,
+	.ref	= usb_streamlabs_wdt_ref,
+	.unref	= usb_streamlabs_wdt_unref,
+};
+
+static int usb_streamlabs_wdt_probe(struct usb_interface *intf,
+			const struct usb_device_id *id)
+{
+	struct usb_device *dev = interface_to_usbdev(intf);
+	struct streamlabs_wdt *streamlabs_wdt;
+	int retval;
+
+	/* USB IDs of this device appear to be weird/unregistered. Hence, do
+	 * an additional check on product and manufacturer.
+	 * If there is similar device in the field with same values then
+	 * there is stop command in probe() below that checks if the device
+	 * behaves as a watchdog. */
+	if (dev->product && dev->manufacturer &&
+		(strncmp(dev->product, "USBkit", 6) != 0
+		|| strncmp(dev->manufacturer, "STREAM LABS", 11) != 0))
+		return -ENODEV;
+
+	streamlabs_wdt = kmalloc(sizeof(struct streamlabs_wdt), GFP_KERNEL);
+	if (!streamlabs_wdt) {
+		dev_err(&intf->dev, "kmalloc failed\n");
+		return -ENOMEM;
+	}
+
+	streamlabs_wdt->buffer = kzalloc(BUFFER_LENGTH, GFP_KERNEL);
+	if (!streamlabs_wdt->buffer) {
+		dev_err(&intf->dev, "kzalloc for watchdog->buffer failed\n");
+		retval = -ENOMEM;
+		goto err_nobuf;
+	}
+
+	mutex_init(&streamlabs_wdt->lock);
+
+	streamlabs_wdt->wdt_dev.info = &streamlabs_wdt_ident;
+	streamlabs_wdt->wdt_dev.ops = &usb_streamlabs_wdt_ops;
+	streamlabs_wdt->wdt_dev.timeout = STREAMLABS_WDT_MAX_TIMEOUT;
+	streamlabs_wdt->wdt_dev.max_timeout = STREAMLABS_WDT_MAX_TIMEOUT;
+	streamlabs_wdt->wdt_dev.min_timeout = STREAMLABS_WDT_MIN_TIMEOUT;
+	streamlabs_wdt->wdt_dev.parent = &intf->dev;
+
+	streamlabs_wdt->usbdev = interface_to_usbdev(intf);
+	streamlabs_wdt->intf = intf;
+	usb_set_intfdata(intf, &streamlabs_wdt->wdt_dev);
+	watchdog_set_drvdata(&streamlabs_wdt->wdt_dev, streamlabs_wdt);
+
+	watchdog_init_timeout(&streamlabs_wdt->wdt_dev,
+				streamlabs_wdt->wdt_dev.timeout, &intf->dev);
+	watchdog_set_nowayout(&streamlabs_wdt->wdt_dev, nowayout);
+
+	kref_init(&streamlabs_wdt->kref);
+
+	retval = usb_streamlabs_wdt_stop(&streamlabs_wdt->wdt_dev);
+	if (retval)
+		goto err_wdt_buf;
+
+	retval = watchdog_register_device(&streamlabs_wdt->wdt_dev);
+	if (retval) {
+		dev_err(&intf->dev, "failed to register watchdog device\n");
+		goto err_wdt_buf;
+	}
+
+	dev_info(&intf->dev, "StreamLabs USB watchdog loaded.\n");
+
+	return 0;
+
+err_wdt_buf:
+	mutex_destroy(&streamlabs_wdt->lock);
+	kfree(streamlabs_wdt->buffer);
+
+err_nobuf:
+	kfree(streamlabs_wdt);
+	return retval;
+}
+
+
+
+static int usb_streamlabs_wdt_suspend(struct usb_interface *intf,
+					pm_message_t message)
+{
+	struct streamlabs_wdt *streamlabs_wdt = usb_get_intfdata(intf);
+
+	if (watchdog_active(&streamlabs_wdt->wdt_dev))
+		usb_streamlabs_wdt_command(&streamlabs_wdt->wdt_dev,
+							STREAMLABS_CMD_STOP);
+
+	return 0;
+}
+
+static int usb_streamlabs_wdt_resume(struct usb_interface *intf)
+{
+	struct streamlabs_wdt *streamlabs_wdt = usb_get_intfdata(intf);
+
+	if (watchdog_active(&streamlabs_wdt->wdt_dev))
+		return usb_streamlabs_wdt_command(&streamlabs_wdt->wdt_dev,
+							STREAMLABS_CMD_START);
+
+	return 0;
+}
+
+static void usb_streamlabs_wdt_disconnect(struct usb_interface *intf)
+{
+	struct streamlabs_wdt *streamlabs_wdt = usb_get_intfdata(intf);
+
+	/* First, stop sending USB messages to device. */
+	mutex_lock(&streamlabs_wdt->lock);
+	usb_set_intfdata(intf, NULL);
+	streamlabs_wdt->usbdev = NULL;
+	mutex_unlock(&streamlabs_wdt->lock);
+
+	/* after commincation with device has stopped we can
+	 * unregister watchdog device. unref callback will clear the rest on
+	 * release of device if it was opened.
+	 */
+	watchdog_unregister_device(&streamlabs_wdt->wdt_dev);
+	kref_put(&streamlabs_wdt->kref, usb_streamlabs_wdt_release_resources);
+}
+
+static struct usb_device_id usb_streamlabs_wdt_device_table[] = {
+	{ USB_DEVICE(USB_STREAMLABS_WATCHDOG_VENDOR, USB_STREAMLABS_WATCHDOG_PRODUCT) },
+	{ }	/* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE(usb, usb_streamlabs_wdt_device_table);
+
+static struct usb_driver usb_streamlabs_wdt_driver = {
+	.name		= DRIVER_NAME,
+	.probe		= usb_streamlabs_wdt_probe,
+	.disconnect	= usb_streamlabs_wdt_disconnect,
+	.suspend	= usb_streamlabs_wdt_suspend,
+	.resume		= usb_streamlabs_wdt_resume,
+	.reset_resume	= usb_streamlabs_wdt_resume,
+	.id_table	= usb_streamlabs_wdt_device_table,
+};
+
+module_usb_driver(usb_streamlabs_wdt_driver);
-- 
2.7.0.rc3

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