Re: [PATCH 4/5] watchdog: Add Hexagon EFI watchdog driver

Ahmad Fatoum
2026-02-06T13:14:36Z

On 2/5/26 4:45 PM, Marco Felsch wrote:
> The EFI system co-processor implements a watchdog device which must be
> pinged to inform the MCU that the system is up and running.
>
> Normaly the ping is done by Linux but sometimes it can become necessary
> to do it within barebox too, e.g. to allow barebox debugging and
> development.
>
> Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
> ---
> drivers/watchdog/Kconfig | 9 +++++
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/hgs_efi_wdt.c | 88 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 98 insertions(+)
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index bf18782bdb58b20240d7762ce32f98c78c4cd12d..c962e8f22e5a7cb21ee93b3f82189cc8536781b9 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -195,4 +195,13 @@ config K3_RTI_WDT
> Say Y here if you want to include support for the K3 watchdog
> timer (RTI module) available in the K3 generation of processors.
>
> +config HGS_EFI_WATCHDOG
> + bool "Hexagon Geosystems EFI watchdog"
> + depends on MFD_HGS_EFI || COMPILE_TEST

Thanks for making sure it compiles under COMPILE_TEST. :)

> +#include <mfd/hgs-efi.h>
> +
> +struct hgs_efi_wdt_data {
> + unsigned int msg_id;
> +};
> +
> +struct hgs_efi_wdt {
> + struct watchdog wdd;
> + struct hgs_efi *efi;
> + const struct hgs_efi_wdt_data *data;
> + bool is_running;

This is only ever read, but set no where.

> +};
> +
> +static struct hgs_efi_wdt *to_hgs_efi_wdt(struct watchdog *wdd)
> +{
> + return container_of(wdd, struct hgs_efi_wdt, wdd);
> +}
> +
> +static int hgs_efi_wdt_set_timeout(struct watchdog *wdd, unsigned int timeout)
> +{
> + struct hgs_efi_wdt *efi_wd = to_hgs_efi_wdt(wdd);
> + struct device *dev = &wdd->dev;
> + struct hgs_sep_cmd cmd = {
> + .type = HGS_SEP_MSG_TYPE_EVENT,
> + .msg_id = efi_wd->data->msg_id,
> + };
> + int ret;
> +
> + /* The watchdog can't be turned of */
> + if (efi_wd->is_running && !timeout)
> + return -ENOSYS;
> +
> + /* The EFI watchdog doesn't have a timeout, once pinged */
> + if (efi_wd->is_running)
> + return 0;

A watchdog can also implement a ping callback, which may be suitable here.

> +static int hgs_efi_wdt_drv_probe(struct device *dev)
> +{
> + struct hgs_efi_wdt *efi_wd;
> + struct watchdog *wdd;
> + int ret;
> +
> + efi_wd = xzalloc(sizeof(*efi_wd));
> + efi_wd->efi = dev_get_priv(dev->parent);
> + efi_wd->data = of_device_get_match_data(dev);
> +
> + wdd = &efi_wd->wdd;
> + wdd->hwdev = dev;
> + wdd->set_timeout = hgs_efi_wdt_set_timeout;

FYI, if you can query the EFI whether it's enabled, you can set
wdd->running to either WDOG_HW_RUNNING or WDOG_HW_NOT_RUNNING

> +
> + ret = watchdog_register(wdd);
> + if (ret)
> + dev_err(dev, "Failed to register watchdog device\n");
> +
> + return ret;
> +}
> +
> +const struct hgs_efi_wdt_data hgs_efi_wdt_gs05 = {
> + .msg_id = 0,
> +};
> +
> +static struct of_device_id hgs_efi_wdt_of_match[] = {
> + { .compatible = "hgs,efi-gs05-wdt", .data = &hgs_efi_wdt_gs05 },
> + { /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, hgs_efi_wdt_of_match);
> +
> +static struct driver hgs_efi_wdt_driver = {
> + .name = "hgs-efi-wdt",
> + .probe = hgs_efi_wdt_drv_probe,
> + .of_compatible = hgs_efi_wdt_of_match,
> +};
> +device_platform_driver(hgs_efi_wdt_driver);
>

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