From fa01fa70039cd969acde606672e2b9846205bd0f Mon Sep 17 00:00:00 2001 From: Wolfram Sang Date: Sat, 19 Dec 2020 18:34:15 +0100 Subject: watchdog: renesas_wdt: don't sleep in atomic context MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In the restart handler, we hit multiple OOPSes. One because of usleep_range() and one because of RPM. So, instead of re-using rwdt_start(), we implement an atomic version of it in the restart handler. As a little bonus, reboot will occur sooner because we can now use the smallest divider in the custom restart routine. Signed-off-by: Wolfram Sang Reviewed-by: Guenter Roeck Reviewed-by: Geert Uytterhoeven Reviewed-by: Niklas Söderlund Link: https://lore.kernel.org/r/20201219173415.21848-1-wsa+renesas@sang-engineering.com Signed-off-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck --- drivers/watchdog/renesas_wdt.c | 30 ++++++++++++++++++++++++------ 1 file changed, 24 insertions(+), 6 deletions(-) (limited to 'drivers/watchdog') diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c index 47fce4de0110..d2b5074bca65 100644 --- a/drivers/watchdog/renesas_wdt.c +++ b/drivers/watchdog/renesas_wdt.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include #include @@ -50,6 +51,7 @@ struct rwdt_priv { struct watchdog_device wdev; unsigned long clk_rate; u8 cks; + struct clk *clk; }; static void rwdt_write(struct rwdt_priv *priv, u32 val, unsigned int reg) @@ -125,13 +127,30 @@ static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev) return DIV_BY_CLKS_PER_SEC(priv, 65536 - val); } +/* needs to be atomic - no RPM, no usleep_range, no scheduling! */ static int rwdt_restart(struct watchdog_device *wdev, unsigned long action, void *data) { struct rwdt_priv *priv = watchdog_get_drvdata(wdev); + u8 val; + + clk_prepare_enable(priv->clk); + + /* Stop the timer before we modify any register */ + val = readb_relaxed(priv->base + RWTCSRA) & ~RWTCSRA_TME; + rwdt_write(priv, val, RWTCSRA); + /* Delay 2 cycles before setting watchdog counter */ + udelay(DIV_ROUND_UP(2 * 1000000, priv->clk_rate)); - rwdt_start(wdev); rwdt_write(priv, 0xffff, RWTCNT); + /* smallest divider to reboot soon */ + rwdt_write(priv, 0, RWTCSRA); + + readb_poll_timeout_atomic(priv->base + RWTCSRA, val, + !(val & RWTCSRA_WRFLG), 1, 100); + + rwdt_write(priv, RWTCSRA_TME, RWTCSRA); + return 0; } @@ -191,7 +210,6 @@ static int rwdt_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; struct rwdt_priv *priv; - struct clk *clk; unsigned long clks_per_sec; int ret, i; u8 csra; @@ -207,13 +225,13 @@ static int rwdt_probe(struct platform_device *pdev) if (IS_ERR(priv->base)) return PTR_ERR(priv->base); - clk = devm_clk_get(dev, NULL); - if (IS_ERR(clk)) - return PTR_ERR(clk); + priv->clk = devm_clk_get(dev, NULL); + if (IS_ERR(priv->clk)) + return PTR_ERR(priv->clk); pm_runtime_enable(dev); pm_runtime_get_sync(dev); - priv->clk_rate = clk_get_rate(clk); + priv->clk_rate = clk_get_rate(priv->clk); csra = readb_relaxed(priv->base + RWTCSRA); priv->wdev.bootstatus = csra & RWTCSRA_WOVF ? WDIOF_CARDRESET : 0; pm_runtime_put(dev); -- cgit v1.2.3