Hi Rasmus, On Mon, 10 May 2021 at 09:47, Rasmus Villemoes <rasmus.villem...@prevas.dk> wrote: > > A rather common kind of external watchdog circuit is one that is kept > alive by toggling a gpio. Add a driver for handling such a watchdog. > > The compatible string is probably a little odd as it has nothing to do > with linux per se - however, I chose that to make .dts snippets > reusable between device trees used with U-Boot and linux, and this is > the (only) compatible string that linux' corresponding driver and DT > binding accepts. I have asked whether one should/could add "wdt-gpio" > to that binding, but the answer was no: > > > https://lore.kernel.org/lkml/CAL_JsqKEGaFpiFV_oAtE+S_bnHkg4qry+bhx2EDs=nsbvf_...@mail.gmail.com/ > > If someone feels strongly about this, I can certainly remove the > "linux," part from the string - it probably wouldn't the only place where > one can't reuse a DT snippet as-is between linux and U-Boot.
It seems fine to me. We share DT bindings with Linux anyway. > > Signed-off-by: Rasmus Villemoes <rasmus.villem...@prevas.dk> > --- > .../watchdog/gpio-wdt.txt | 15 ++++++ > drivers/watchdog/Kconfig | 7 +++ > drivers/watchdog/Makefile | 1 + > drivers/watchdog/gpio_wdt.c | 51 +++++++++++++++++++ > 4 files changed, 74 insertions(+) > create mode 100644 doc/device-tree-bindings/watchdog/gpio-wdt.txt > create mode 100644 drivers/watchdog/gpio_wdt.c > > diff --git a/doc/device-tree-bindings/watchdog/gpio-wdt.txt > b/doc/device-tree-bindings/watchdog/gpio-wdt.txt > new file mode 100644 > index 0000000000..2283b7ba6e > --- /dev/null > +++ b/doc/device-tree-bindings/watchdog/gpio-wdt.txt > @@ -0,0 +1,15 @@ > +GPIO watchdog timer > + > +Describes a simple watchdog timer which is reset by toggling a gpio. > + > +Required properties: > + > +- compatible: must be "linux,wdt-gpio" > +- gpios: gpio to toggle when wdt driver reset method is called > + > +Example: > + > + gpio-wdt { > + gpios = <&gpio0 1 0>; > + compatible = "linux,wdt-gpio"; > + }; > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig > index f0ff2612a6..2cf378db29 100644 > --- a/drivers/watchdog/Kconfig > +++ b/drivers/watchdog/Kconfig > @@ -147,6 +147,13 @@ config WDT_CORTINA > This driver support all CPU ISAs supported by Cortina > Access CAxxxx SoCs. > > +config WDT_GPIO > + bool "External gpio watchdog support" > + depends on WDT > + depends on DM_GPIO > + help > + Support for external watchdog fed by toggling a gpio. please add a bit more detail. How do you configure it? e.g. point to the binding file (which you should add to U-Boot if not there). > + > config WDT_MPC8xx > bool "MPC8xx watchdog timer support" > depends on WDT && MPC8xx > diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile > index 5c7ef593fe..f14415bb8e 100644 > --- a/drivers/watchdog/Makefile > +++ b/drivers/watchdog/Makefile > @@ -25,6 +25,7 @@ obj-$(CONFIG_WDT_BOOKE) += booke_wdt.o > obj-$(CONFIG_WDT_CORTINA) += cortina_wdt.o > obj-$(CONFIG_WDT_ORION) += orion_wdt.o > obj-$(CONFIG_WDT_CDNS) += cdns_wdt.o > +obj-$(CONFIG_WDT_GPIO) += gpio_wdt.o > obj-$(CONFIG_WDT_MPC8xx) += mpc8xx_wdt.o > obj-$(CONFIG_WDT_MT7620) += mt7620_wdt.o > obj-$(CONFIG_WDT_MT7621) += mt7621_wdt.o > diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c > new file mode 100644 > index 0000000000..9dba9c254e > --- /dev/null > +++ b/drivers/watchdog/gpio_wdt.c > @@ -0,0 +1,51 @@ > +// SPDX-License-Identifier: GPL-2.0+ > + > +#include <common.h> > +#include <dm.h> > +#include <dm/device_compat.h> > +#include <wdt.h> > +#include <asm/gpio.h> > + > +struct gpio_wdt_priv { > + struct gpio_desc gpio; > + int state; bool ? > +}; > + > +static int gpio_wdt_reset(struct udevice *dev) > +{ > + struct gpio_wdt_priv *priv = dev_get_priv(dev); > + > + priv->state = !priv->state; blank line before final return (please fix below also) > + return dm_gpio_set_value(&priv->gpio, priv->state); > +} > + > +static int dm_probe(struct udevice *dev) > +{ > + struct gpio_wdt_priv *priv = dev_get_priv(dev); > + int ret; > + > + ret = gpio_request_by_name(dev, "gpios", 0, &priv->gpio, > GPIOD_IS_OUT); > + if (ret < 0) { > + dev_err(dev, "Request for wdt gpio failed: %d\n", ret); > + return ret; > + } > + return gpio_wdt_reset(dev); > +} > + > +static const struct wdt_ops gpio_wdt_ops = { > + .reset = gpio_wdt_reset, > +}; > + > +static const struct udevice_id gpio_wdt_ids[] = { > + { .compatible = "linux,wdt-gpio" }, > + {} > +}; > + > +U_BOOT_DRIVER(wdt_gpio) = { > + .name = "wdt_gpio", > + .id = UCLASS_WDT, > + .of_match = gpio_wdt_ids, > + .ops = &gpio_wdt_ops, > + .probe = dm_probe, > + .priv_auto = sizeof(struct gpio_wdt_priv), > +}; > -- > 2.29.2 > Regards, Simon