From 258aa7d2d427f812341c79678c885dd7d7796507 Mon Sep 17 00:00:00 2001 From: Paul Doelle Date: Mon, 4 Jul 2022 09:00:25 +0000 Subject: [PATCH] watchdog: add pulse support to gpio watchdog driver A common external watchdog circuit is kept alive by triggering a short pulse on the reset pin. This patch adds support for this use case, while making the algorithm configurable in the devicetree. The "linux,wdt-gpio" driver being modified is based off the equivalent driver in the Linux kernel, which provides support for this algorithm. This patch brings parity to this driver, and is kept aligned with the functionality and devicetree configuration in the kernel. It should be noted that this adds a required property named 'hw_algo' to the devicetree binding, following suit with the kernel. I'm happy to make this backward-compatible if preferred. Signed-off-by: Paul Doelle Reviewed-by: Stefan Roese --- arch/sandbox/dts/test.dts | 11 ++++- .../watchdog/gpio-wdt.txt | 8 +++- drivers/watchdog/gpio_wdt.c | 40 +++++++++++++--- test/dm/wdt.c | 46 ++++++++++++++++--- 4 files changed, 90 insertions(+), 15 deletions(-) diff --git a/arch/sandbox/dts/test.dts b/arch/sandbox/dts/test.dts index 0194b9b30e..d1a8cc7bfb 100644 --- a/arch/sandbox/dts/test.dts +++ b/arch/sandbox/dts/test.dts @@ -850,10 +850,19 @@ }; }; - gpio-wdt { + wdt-gpio-toggle { gpios = <&gpio_a 7 0>; compatible = "linux,wdt-gpio"; hw_margin_ms = <100>; + hw_algo = "toggle"; + always-running; + }; + + wdt-gpio-level { + gpios = <&gpio_a 7 0>; + compatible = "linux,wdt-gpio"; + hw_margin_ms = <100>; + hw_algo = "level"; always-running; }; diff --git a/doc/device-tree-bindings/watchdog/gpio-wdt.txt b/doc/device-tree-bindings/watchdog/gpio-wdt.txt index c9a8559a3e..746c2c081e 100644 --- a/doc/device-tree-bindings/watchdog/gpio-wdt.txt +++ b/doc/device-tree-bindings/watchdog/gpio-wdt.txt @@ -5,7 +5,12 @@ 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. +- gpios: From common gpio binding; gpio connection to WDT reset pin. +- hw_algo: The algorithm used by the driver. Should be one of the + following values: + - toggle: Toggle from high-to-low or low-to-high when resetting the watchdog. + - level: Maintain a constant high/low level, and trigger a short pulse when + resetting the watchdog. Active level is determined by the GPIO flags. - always-running: Boolean property indicating that the watchdog cannot be disabled. At present, U-Boot only supports this kind of GPIO watchdog. @@ -15,5 +20,6 @@ Example: gpio-wdt { gpios = <&gpio0 1 0>; compatible = "linux,wdt-gpio"; + hw_algo = "toggle"; always-running; }; diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c index 982a66b3f9..fe06ec8cc9 100644 --- a/drivers/watchdog/gpio_wdt.c +++ b/drivers/watchdog/gpio_wdt.c @@ -4,20 +4,38 @@ #include #include #include +#include + +enum { + HW_ALGO_TOGGLE, + HW_ALGO_LEVEL, +}; struct gpio_wdt_priv { - struct gpio_desc gpio; - bool always_running; - int state; + struct gpio_desc gpio; + unsigned int hw_algo; + bool always_running; + int state; }; static int gpio_wdt_reset(struct udevice *dev) { struct gpio_wdt_priv *priv = dev_get_priv(dev); - priv->state = !priv->state; - - return dm_gpio_set_value(&priv->gpio, priv->state); + switch (priv->hw_algo) { + case HW_ALGO_TOGGLE: + /* Toggle output pin */ + priv->state = !priv->state; + dm_gpio_set_value(&priv->gpio, priv->state); + break; + case HW_ALGO_LEVEL: + /* Pulse */ + dm_gpio_set_value(&priv->gpio, 1); + udelay(1); + dm_gpio_set_value(&priv->gpio, 0); + break; + } + return 0; } static int gpio_wdt_start(struct udevice *dev, u64 timeout, ulong flags) @@ -34,6 +52,16 @@ static int dm_probe(struct udevice *dev) { struct gpio_wdt_priv *priv = dev_get_priv(dev); int ret; + const char *algo = dev_read_string(dev, "hw_algo"); + + if (!algo) + return -EINVAL; + if (!strcmp(algo, "toggle")) + priv->hw_algo = HW_ALGO_TOGGLE; + else if (!strcmp(algo, "level")) + priv->hw_algo = HW_ALGO_LEVEL; + else + return -EINVAL; priv->always_running = dev_read_bool(dev, "always-running"); ret = gpio_request_by_name(dev, "gpios", 0, &priv->gpio, GPIOD_IS_OUT); diff --git a/test/dm/wdt.c b/test/dm/wdt.c index ee615f0e14..535f00a874 100644 --- a/test/dm/wdt.c +++ b/test/dm/wdt.c @@ -44,20 +44,20 @@ static int dm_test_wdt_base(struct unit_test_state *uts) } DM_TEST(dm_test_wdt_base, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT); -static int dm_test_wdt_gpio(struct unit_test_state *uts) +static int dm_test_wdt_gpio_toggle(struct unit_test_state *uts) { /* * The sandbox wdt gpio is "connected" to gpio bank a, offset * 7. Use the sandbox back door to verify that the gpio-wdt - * driver behaves as expected. + * driver behaves as expected when using the 'toggle' algorithm. */ struct udevice *wdt, *gpio; const u64 timeout = 42; const int offset = 7; int val; - ut_assertok(uclass_get_device_by_driver(UCLASS_WDT, - DM_DRIVER_GET(wdt_gpio), &wdt)); + ut_assertok(uclass_get_device_by_name(UCLASS_WDT, + "wdt-gpio-toggle", &wdt)); ut_assertnonnull(wdt); ut_assertok(uclass_get_device_by_name(UCLASS_GPIO, "base-gpios", &gpio)); @@ -74,7 +74,39 @@ static int dm_test_wdt_gpio(struct unit_test_state *uts) return 0; } -DM_TEST(dm_test_wdt_gpio, UT_TESTF_SCAN_FDT); +DM_TEST(dm_test_wdt_gpio_toggle, UT_TESTF_SCAN_FDT); + +static int dm_test_wdt_gpio_level(struct unit_test_state *uts) +{ + /* + * The sandbox wdt gpio is "connected" to gpio bank a, offset + * 7. Use the sandbox back door to verify that the gpio-wdt + * driver behaves as expected when using the 'level' algorithm. + */ + struct udevice *wdt, *gpio; + const u64 timeout = 42; + const int offset = 7; + int val; + + ut_assertok(uclass_get_device_by_name(UCLASS_WDT, + "wdt-gpio-level", &wdt)); + ut_assertnonnull(wdt); + + ut_assertok(uclass_get_device_by_name(UCLASS_GPIO, "base-gpios", &gpio)); + ut_assertnonnull(gpio); + ut_assertok(wdt_start(wdt, timeout, 0)); + + val = sandbox_gpio_get_value(gpio, offset); + ut_assertok(wdt_reset(wdt)); + ut_asserteq(val, sandbox_gpio_get_value(gpio, offset)); + ut_assertok(wdt_reset(wdt)); + ut_asserteq(val, sandbox_gpio_get_value(gpio, offset)); + + ut_asserteq(-ENOSYS, wdt_stop(wdt)); + + return 0; +} +DM_TEST(dm_test_wdt_gpio_level, UT_TESTF_SCAN_FDT); static int dm_test_wdt_watchdog_reset(struct unit_test_state *uts) { @@ -86,8 +118,8 @@ static int dm_test_wdt_watchdog_reset(struct unit_test_state *uts) uint reset_count; int val; - ut_assertok(uclass_get_device_by_driver(UCLASS_WDT, - DM_DRIVER_GET(wdt_gpio), &gpio_wdt)); + ut_assertok(uclass_get_device_by_name(UCLASS_WDT, + "wdt-gpio-toggle", &gpio_wdt)); ut_assertnonnull(gpio_wdt); ut_assertok(uclass_get_device_by_driver(UCLASS_WDT, DM_DRIVER_GET(wdt_sandbox), &sandbox_wdt)); -- 2.39.5