Re: [PATCH v3] watchdog: add driver for StreamLabs USB watchdog device
From: Guenter Roeck
Date: Fri Feb 17 2017 - 05:56:05 EST
On 02/17/2017 01:25 AM, Alexey Klimov wrote:
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@xxxxxxxxx>
---
Changes in v3:
-- coding style cleanups and rebase;
-- buffer is allocated with separate allocation;
-- adding comments about max/min limits;
-- rework start/stop commands implementation;
-- fix first if-check in probe() function;
Previous version: https://www.spinics.net/lists/linux-watchdog/msg09092.html
drivers/watchdog/Kconfig | 16 ++
drivers/watchdog/Makefile | 1 +
drivers/watchdog/streamlabs_wdt.c | 321 ++++++++++++++++++++++++++++++++++++++
3 files changed, 338 insertions(+)
create mode 100644 drivers/watchdog/streamlabs_wdt.c
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index acb00b53a520..6a2195d8cc5c 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1852,6 +1852,22 @@ 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.
+
comment "Watchdog Pretimeout Governors"
config WATCHDOG_PRETIMEOUT_GOV
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 0c3d35e3c334..d4a61222ccd2 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -31,6 +31,7 @@ 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 000000000000..4442d053d9f7
--- /dev/null
+++ b/drivers/watchdog/streamlabs_wdt.c
@@ -0,0 +1,321 @@
+/*
+ * StreamLabs USB Watchdog driver
+ *
+ * Copyright (c) 2016-2017 Alexey Klimov <klimov.linux@xxxxxxxxx>
+ *
+ * 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/types.h>
+#include <linux/usb.h>
+#include <linux/watchdog.h>
+#include <asm/byteorder.h>
+
+/*
+ * USB Watchdog device from Streamlabs:
+ * https://www.stream-labs.com/en/catalog/?cat_id=1203&item_id=323
+ *
+ * USB commands have been reverse engineered using usbmon.
+ */
+
+#define DRIVER_AUTHOR "Alexey Klimov <klimov.linux@xxxxxxxxx>"
+#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 0xaacc
+#define STREAMLABS_CMD_STOP 0xbbff
+
+/* timeouts values are taken from windows program */
+#define STREAMLABS_WDT_MIN_TIMEOUT 1
+#define STREAMLABS_WDT_MAX_TIMEOUT 46
+
+struct streamlabs_wdt {
+ struct watchdog_device wdt_dev;
+ struct usb_interface *intf;
+
+ struct mutex lock;
+ u8 *buffer;
+};
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+
+/*
+ * This function is used to check if watchdog actually changed
+ * its state to disabled that is reported in first two bytes of response
+ * message.
+ */
+static int usb_streamlabs_wdt_check_stop(u16 *buf)
+{
+ if (buf[0] != cpu_to_le16(STREAMLABS_CMD_STOP))
+ return -EINVAL;
+
+ return 0;
+}
+
+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
+ * when response treated as 8bit message.
+ */
+ if (buf[10] != 1 || buf[11] != 2 || buf[12] != 3 || buf[13] != 4)
+ return -EINVAL;
-EPROTO might be a better error return here and above.
+
+ return 0;
+}
+
+static void usb_streamlabs_wdt_prepare_buf(u16 *buf, u16 cmd,
+ unsigned long timeout_msec)
+{
+ /*
+ * remaining elements expected to be zero everytime during
+ * communication
+ */
+ buf[0] = cpu_to_le16(cmd);
+ buf[1] = cpu_to_le16(0x8000);
+ buf[3] = cpu_to_le16(timeout_msec);
+ buf[5] = 0x0;
+ buf[6] = 0x0;
+}
+
+static int usb_streamlabs_wdt_cmd(struct streamlabs_wdt *wdt, u16 cmd)
+{
+ struct usb_device *usbdev;
+ unsigned long timeout_msec;
+ int retval;
+ int size;
+
+ if (unlikely(!wdt->intf))
+ return -ENODEV;
+
+ usbdev = interface_to_usbdev(wdt->intf);
+ timeout_msec = wdt->wdt_dev.timeout * MSEC_PER_SEC;
+
+ usb_streamlabs_wdt_prepare_buf((u16 *) wdt->buffer, cmd, timeout_msec);
+
+ /* send command to watchdog */
+ retval = usb_interrupt_msg(usbdev, usb_sndintpipe(usbdev, 0x02),
+ wdt->buffer, BUFFER_TRANSFER_LENGTH,
+ &size, USB_TIMEOUT);
+ if (retval)
+ return retval;
+
+ if (size != BUFFER_TRANSFER_LENGTH)
+ return -EIO;
+
+ /* and read response from watchdog */
+ retval = usb_interrupt_msg(usbdev, usb_rcvintpipe(usbdev, 0x81),
+ wdt->buffer, BUFFER_LENGTH,
+ &size, USB_TIMEOUT);
+ if (retval)
+ return retval;
+
+ if (size != BUFFER_LENGTH)
+ return -EIO;
+
+ /* check if watchdog actually acked/recognized command */
+ return usb_streamlabs_wdt_validate_response(wdt->buffer);
+}
+
+static int usb_streamlabs_wdt_stop_cmd(struct streamlabs_wdt *wdt)
+{
+ int retry_counter = 10; /* how many times to re-send stop cmd */
+ int retval;
+
+ /*
+ * Transition from enabled to disabled state in this device
+ * for stop command doesn't happen immediately. Usually, 2 or 3
+ * (sometimes even 4) stop commands should be sent until
+ * watchdog answers 'I'm stopped!'.
+ * Retry only stop command if watchdog fails to answer correctly
+ * about its state. After 10 attempts go out and return error.
+ */
+
+ do {
+ retval = usb_streamlabs_wdt_cmd(wdt, STREAMLABS_CMD_STOP);
+ if (retval)
+ break;
+
+ retval = usb_streamlabs_wdt_check_stop((u16 *) wdt->buffer);
+
+ } while (retval && --retry_counter >= 0);
+
+ return retry_counter > 0 ? retval : -EIO;
+}
+
+static int usb_streamlabs_wdt_start(struct watchdog_device *wdt_dev)
+{
+ struct streamlabs_wdt *streamlabs_wdt = watchdog_get_drvdata(wdt_dev);
+ int retval;
+
+ mutex_lock(&streamlabs_wdt->lock);
+ retval = usb_streamlabs_wdt_cmd(streamlabs_wdt, STREAMLABS_CMD_START);
+ mutex_unlock(&streamlabs_wdt->lock);
+
+ return retval;
+}
+
+static int usb_streamlabs_wdt_stop(struct watchdog_device *wdt_dev)
+{
+ struct streamlabs_wdt *streamlabs_wdt = watchdog_get_drvdata(wdt_dev);
+ int retval;
+
+ mutex_lock(&streamlabs_wdt->lock);
+ retval = usb_streamlabs_wdt_stop_cmd(streamlabs_wdt);
+ mutex_unlock(&streamlabs_wdt->lock);
+
+ return retval;
+}
+
+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,
+};
+
+static int usb_streamlabs_wdt_probe(struct usb_interface *intf,
+ const struct usb_device_id *id)
+{
+ struct usb_device *usbdev = 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 (!usbdev->product || !usbdev->manufacturer
+ || strncmp(usbdev->product, "USBkit", 6)
+ || strncmp(usbdev->manufacturer, "STREAM LABS", 11))
+ return -ENODEV;
+
+ streamlabs_wdt = devm_kzalloc(&intf->dev, sizeof(struct streamlabs_wdt),
+ GFP_KERNEL);
+ if (!streamlabs_wdt)
+ return -ENOMEM;
+
+ streamlabs_wdt->buffer = kzalloc(BUFFER_LENGTH, GFP_KERNEL);
Why not use devm_kzalloc() here ? As it is, the buffer leaks in the disconnect
function.
+ if (!streamlabs_wdt->buffer)
+ return -ENOMEM;
+
+ 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->intf = intf;
+ usb_set_intfdata(intf, &streamlabs_wdt->wdt_dev);
+ watchdog_set_drvdata(&streamlabs_wdt->wdt_dev, streamlabs_wdt);
+ watchdog_set_nowayout(&streamlabs_wdt->wdt_dev, nowayout);
+
+ retval = usb_streamlabs_wdt_stop(&streamlabs_wdt->wdt_dev);
+ if (retval)
+ goto free_buf;
+
+ retval = watchdog_register_device(&streamlabs_wdt->wdt_dev);
+ if (retval) {
+ dev_err(&intf->dev, "failed to register watchdog device\n");
+ goto free_buf;
+ }
+
+ dev_info(&intf->dev, "StreamLabs USB watchdog loaded.\n");
+ return 0;
+
+free_buf:
+ kfree(streamlabs_wdt->buffer);
+ 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))
+ return usb_streamlabs_wdt_stop(&streamlabs_wdt->wdt_dev);
+
+ 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_start(&streamlabs_wdt->wdt_dev);
+
+ return 0;
+}
+
+static void usb_streamlabs_wdt_disconnect(struct usb_interface *intf)
+{
+ struct streamlabs_wdt *streamlabs_wdt = usb_get_intfdata(intf);
+
+ mutex_lock(&streamlabs_wdt->lock);
+ usb_streamlabs_wdt_stop_cmd(streamlabs_wdt);
Does that even make sense since the device is in the process of being disconnected ?
+ usb_set_intfdata(intf, NULL);
This is potentially racy: If a suspend happens exactly here, the suspend function
will crash. I don't see the value in setting this to NULL here.
I also wonder if the complexity with the local lock is really necessary. Why not just
unregister the watchdog device (or use devm_watchdog_register_device() to start with) ?
... especially in the context that the stop function is called above.
+ streamlabs_wdt->intf = NULL;
+ mutex_unlock(&streamlabs_wdt->lock);
+
+ watchdog_unregister_device(&streamlabs_wdt->wdt_dev);
+}
+
+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);