6.6-stable review patch. If anyone has any objections, please let me know.
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From: Linus Walleij linus.walleij@linaro.org
[ Upstream commit b4075ecfe348a44209534c75ad72392c63a489a6 ]
The IXP4xx watchdog in early "A0" silicon is unreliable and cannot be registered, however for some systems such as the USRobotics USR8200 the watchdog is the only restart option, so implement a "dummy" watchdog that can only support restart in this case.
Fixes: 1aea522809e6 ("watchdog: ixp4xx: Implement restart") Signed-off-by: Linus Walleij linus.walleij@linaro.org Reviewed-by: Guenter Roeck linux@roeck-us.net Link: https://lore.kernel.org/r/20230926-ixp4xx-wdt-restart-v2-1-15cf4639b423@lina... Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Wim Van Sebroeck wim@linux-watchdog.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/watchdog/ixp4xx_wdt.c | 28 +++++++++++++++++++++++++--- 1 file changed, 25 insertions(+), 3 deletions(-)
diff --git a/drivers/watchdog/ixp4xx_wdt.c b/drivers/watchdog/ixp4xx_wdt.c index 607ce4b8df574..ec0c08652ec2f 100644 --- a/drivers/watchdog/ixp4xx_wdt.c +++ b/drivers/watchdog/ixp4xx_wdt.c @@ -105,6 +105,25 @@ static const struct watchdog_ops ixp4xx_wdt_ops = { .owner = THIS_MODULE, };
+/* + * The A0 version of the IXP422 had a bug in the watchdog making + * is useless, but we still need to use it to restart the system + * as it is the only way, so in this special case we register a + * "dummy" watchdog that doesn't really work, but will support + * the restart operation. + */ +static int ixp4xx_wdt_dummy(struct watchdog_device *wdd) +{ + return 0; +} + +static const struct watchdog_ops ixp4xx_wdt_restart_only_ops = { + .start = ixp4xx_wdt_dummy, + .stop = ixp4xx_wdt_dummy, + .restart = ixp4xx_wdt_restart, + .owner = THIS_MODULE, +}; + static const struct watchdog_info ixp4xx_wdt_info = { .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE @@ -114,14 +133,17 @@ static const struct watchdog_info ixp4xx_wdt_info = {
static int ixp4xx_wdt_probe(struct platform_device *pdev) { + static const struct watchdog_ops *iwdt_ops; struct device *dev = &pdev->dev; struct ixp4xx_wdt *iwdt; struct clk *clk; int ret;
if (!(read_cpuid_id() & 0xf) && !cpu_is_ixp46x()) { - dev_err(dev, "Rev. A0 IXP42x CPU detected - watchdog disabled\n"); - return -ENODEV; + dev_info(dev, "Rev. A0 IXP42x CPU detected - only restart supported\n"); + iwdt_ops = &ixp4xx_wdt_restart_only_ops; + } else { + iwdt_ops = &ixp4xx_wdt_ops; }
iwdt = devm_kzalloc(dev, sizeof(*iwdt), GFP_KERNEL); @@ -141,7 +163,7 @@ static int ixp4xx_wdt_probe(struct platform_device *pdev) iwdt->rate = IXP4XX_TIMER_FREQ;
iwdt->wdd.info = &ixp4xx_wdt_info; - iwdt->wdd.ops = &ixp4xx_wdt_ops; + iwdt->wdd.ops = iwdt_ops; iwdt->wdd.min_timeout = 1; iwdt->wdd.max_timeout = U32_MAX / iwdt->rate; iwdt->wdd.parent = dev;