Messages in this thread | | | Date | Mon, 25 Jul 2022 07:02:55 -0700 | From | Guenter Roeck <> | Subject | Re: [PATCH v5] watchdog: add driver for StreamLabs USB watchdog device |
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On 7/24/22 20:06, Alexey Klimov wrote: > Driver supports StreamLabs usb watchdog device. The device plugs > into 9-pin usb header and connects to reset pins and reset button > pins on desktop PC. > > USB commands used to communicate with device were reverse > engineered using usbmon. > > Signed-off-by: Alexey Klimov <klimov.linux@gmail.com> > --- > Changes since v4: > -- added more comments; > -- added nowayout check in ->disconnect(); > -- completely rework usb_streamlabs_wdt_cmd() -> > __usb_streamlabs_wdt_cmd() and functions > that handle validation of the response; > -- usb sending and receiving msgs are moved to separate > functions; > -- added soft_unbind=1 flag in usb_driver struct > to make it possible to send URBs in ->disconnect(); > -- buffer is declared as __le16 now; > -- made checkpatch.pl --strict happy; > > Previous version: > https://lore.kernel.org/linux-watchdog/20220715234442.3910204-1-klimov.linux@gmail.com/ > > > MAINTAINERS | 6 + > drivers/watchdog/Kconfig | 15 ++ > drivers/watchdog/Makefile | 1 + > drivers/watchdog/streamlabs_wdt.c | 360 ++++++++++++++++++++++++++++++ > 4 files changed, 382 insertions(+) > create mode 100644 drivers/watchdog/streamlabs_wdt.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index 64379c699903..fb31c1823043 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -19190,6 +19190,12 @@ W: http://www.stlinux.com > F: Documentation/networking/device_drivers/ethernet/stmicro/ > F: drivers/net/ethernet/stmicro/stmmac/ > > +STREAMLABS USB WATCHDOG DRIVER > +M: Alexey Klimov <klimov.linux@gmail.com> > +L: linux-watchdog@vger.kernel.org > +S: Maintained > +F: drivers/watchdog/streamlabs_wdt.c > + > SUN3/3X > M: Sam Creasey <sammy@sammy.net> > S: Maintained > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig > index 32fd37698932..64b7f947b196 100644 > --- a/drivers/watchdog/Kconfig > +++ b/drivers/watchdog/Kconfig > @@ -2171,6 +2171,21 @@ 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. > + > config KEEMBAY_WATCHDOG > tristate "Intel Keem Bay SoC non-secure watchdog" > depends on ARCH_KEEMBAY || (ARM64 && COMPILE_TEST) > diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile > index c324e9d820e9..2d601da9b5bd 100644 > --- a/drivers/watchdog/Makefile > +++ b/drivers/watchdog/Makefile > @@ -33,6 +33,7 @@ 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..f1130fe5559c > --- /dev/null > +++ b/drivers/watchdog/streamlabs_wdt.c > @@ -0,0 +1,360 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * StreamLabs USB Watchdog driver > + * > + * Copyright (c) 2016-2017,2022 Alexey Klimov <klimov.linux@gmail.com> > + */ > + > +#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/products/devices/watch-dog/ > + * > + * USB commands have been reverse engineered using usbmon. > + */ > + > +#define DRIVER_AUTHOR "Alexey Klimov <klimov.linux@gmail.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 > + Comment about the unit (ms) might be useful.
> +#define STREAMLABS_CMD_START 0xaacc > +#define STREAMLABS_CMD_STOP 0xbbff > + > +/* timeout 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; > + /* Serialises usb communication with a device */ > + struct mutex lock; > + __le16 *buffer; > +}; > + > +static bool nowayout = WATCHDOG_NOWAYOUT; > +module_param(nowayout, bool, 0); > +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" > + __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); > + > +/* USB call wrappers to send and receive messages to/from the device. */ > +static int usb_streamlabs_send_msg(struct usb_device *usbdev, __le16 *buf) > +{ > + int retval; > + int size; > + > + retval = usb_interrupt_msg(usbdev, usb_sndintpipe(usbdev, 0x02), > + buf, BUFFER_TRANSFER_LENGTH, > + &size, USB_TIMEOUT); > + > + if (size != BUFFER_TRANSFER_LENGTH) > + return -EIO; > +
If usb_interrupt_msg() returns an error, it will likely not set size, which may result in a random -EIO. I think this should be something like
if (retval) return retval; if (size != BUFFER_TRANSFER_LENGTH) return -EIO;
return 0;
> + return retval; > +} > + > +static int usb_streamlabs_get_msg(struct usb_device *usbdev, __le16 *buf) > +{ > + int retval; > + int size; > + > + retval = usb_interrupt_msg(usbdev, usb_rcvintpipe(usbdev, 0x81), > + buf, BUFFER_LENGTH, > + &size, USB_TIMEOUT); > + > + if (size != BUFFER_LENGTH) > + return -EIO; > + Same here.
> + return retval; > +} > + > +/* > + * This function is used to check if watchdog timeout in the received buffer > + * matches the timeout passed from watchdog subsystem. > + */ > +static int usb_streamlabs_wdt_check_timeout(__le16 *buf, unsigned long timeout) > +{ > + if (buf[3] != cpu_to_le16(timeout)) > + return -EPROTO; > + > + return 0; > +} > + > +static int usb_streamlabs_wdt_check_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 -EPROTO; > + > + return 0; > +} > + > +/* > + * This function is used to check if watchdog command in the received buffer > + * matches the command passed to the device. > + */ > +static int usb_streamlabs_wdt_check_command(__le16 *buf, u16 cmd) > +{ > + if (buf[0] != cpu_to_le16(cmd)) > + return -EPROTO; > + > + return 0; > +} > + > +static int usb_streamlabs_wdt_validate_response(__le16 *buf, u16 cmd, > + unsigned long timeout_msec) > +{ > + int retval; > + > + retval = usb_streamlabs_wdt_check_response((u8 *)buf); > + if (retval) > + return retval; > + > + retval = usb_streamlabs_wdt_check_command(buf, cmd); > + if (retval) > + return retval; > + > + retval = usb_streamlabs_wdt_check_timeout(buf, timeout_msec); > + return retval;
assignment to retval is unnecessary.
> +} > + > +static void usb_streamlabs_wdt_prepare_buf(__le16 *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);
Not setting buf[2] and buf[4] contradicts the comment above. Maybe those offsets are not _expected_ to be set by the device, but that is not guaranteed. It may be safer to just use memset() at the beginning of the function to clear the buffer.
> + 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; > + /* how many times to re-try getting the state of the device */ > + unsigned int retry_counter = 10; > + int retval; > + > + 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(wdt->buffer, cmd, timeout_msec); > + > + /* send command to watchdog */ > + retval = usb_streamlabs_send_msg(usbdev, wdt->buffer); > + if (retval) > + return retval; > + > + /* > + * Transition from one state to another in this device > + * doesn't happen immediately, especially stopping the device > + * is not observed on the first reading of the response. > + * Plus to avoid potentially stale response message in the device > + * we keep reading the state of the device until we see: > + * -- that device recognised the sent command; > + * -- the received state (started or stopped) matches the state > + * that was requested; > + * -- the timeout passed matches the timeout value read from > + * the device. > + * Keep retrying 10 times and if watchdog device doesn't respond > + * correctly as expected we bail out and return an error. > + */ > + do { > + retval = usb_streamlabs_get_msg(usbdev, wdt->buffer); > + if (retval) > + break; > + > + retval = usb_streamlabs_wdt_validate_response(wdt->buffer, cmd, > + timeout_msec); > + } while (retval && retry_counter--); > + > + return retry_counter ? retval : -EIO; > +} > + > +static int usb_streamlabs_wdt_cmd(struct streamlabs_wdt *streamlabs_wdt, u16 cmd) > +{ > + int retval; > + > + mutex_lock(&streamlabs_wdt->lock); > + retval = __usb_streamlabs_wdt_cmd(streamlabs_wdt, cmd); > + mutex_unlock(&streamlabs_wdt->lock); > + > + return retval; > +} > + > +static int usb_streamlabs_wdt_start(struct watchdog_device *wdt_dev) > +{ > + struct streamlabs_wdt *streamlabs_wdt = watchdog_get_drvdata(wdt_dev); > + > + return usb_streamlabs_wdt_cmd(streamlabs_wdt, STREAMLABS_CMD_START); > +} > + > +static int usb_streamlabs_wdt_stop(struct watchdog_device *wdt_dev) > +{ > + struct streamlabs_wdt *streamlabs_wdt = watchdog_get_drvdata(wdt_dev); > + > + return usb_streamlabs_wdt_cmd(streamlabs_wdt, STREAMLABS_CMD_STOP); > +} > + > +static const struct watchdog_info streamlabs_wdt_ident = { > + .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, > + .identity = DRIVER_NAME, > +}; > + > +static const 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 = devm_kzalloc(&intf->dev, BUFFER_LENGTH, > + GFP_KERNEL); > + if (!streamlabs_wdt->buffer) > + return -ENOMEM; > +
Nit: buffer could be made part of struct streamlabs_wdt and be tagged with ____cacheline_aligned to avoid the double allocation.
> + 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) > + return -ENODEV; > +
A comment explaining why the watchdog is explicitly stopped when running might be useful.
> + retval = devm_watchdog_register_device(&intf->dev, > + &streamlabs_wdt->wdt_dev); > + if (retval) { > + dev_err(&intf->dev, "failed to register watchdog device\n"); > + return retval; > + } > + > + dev_info(&intf->dev, "StreamLabs USB watchdog driver loaded.\n"); > + return 0; > +} > + > +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); > + /* > + * If disconnect happens via sysfs or on rmmod, then try to stop > + * the watchdog. In case of physical detachment of the device this call > + * will fail but we continue. > + */ > + if (!nowayout) > + __usb_streamlabs_wdt_cmd(streamlabs_wdt, STREAMLABS_CMD_STOP); > + /* Stop sending (new) messages to the device */ > + streamlabs_wdt->intf = NULL; > + mutex_unlock(&streamlabs_wdt->lock); > +} > + > +static const 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, > + .soft_unbind = 1, > +}; > + > +module_usb_driver(usb_streamlabs_wdt_driver);
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