On 12/19/20 9:34 AM, Wolfram Sang wrote:
> 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 <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
>
> It is problematic to add a Fixes: tag because we would need three of
> them. So, I'd think we add a stable tag and as long as the patch
> applies, all is fine. Other opinions?
>
> drivers/watchdog/renesas_wdt.c | 30 ++++++++++++++++++++++++------
> 1 file changed, 24 insertions(+), 6 deletions(-)
>
> 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 <linux/clk.h>
> #include <linux/delay.h>
> #include <linux/io.h>
> +#include <linux/iopoll.h>
> #include <linux/kernel.h>
> #include <linux/module.h>
> #include <linux/of.h>
> @@ -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);
>
