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Date: Fri, 17 Feb 2017 02:55:55 -0800 From: Guenter Roeck <linux@...ck-us.net> To: Alexey Klimov <klimov.linux@...il.com>, linux-watchdog@...r.kernel.org Cc: wim@...ana.be, oneukum@...e.com, linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org, yury.norov@...il.com Subject: Re: [PATCH v3] watchdog: add driver for StreamLabs USB watchdog device 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@...il.com> > --- > > 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@...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/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@...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 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); >
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