Re: [PATCH v2 5/7] watchdog: imx7ulp_wdt: Handle wdog reconfigure failure

From: Guenter Roeck
Date: Sun Sep 25 2022 - 13:38:35 EST

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On Thu, Aug 25, 2022 at 04:32:54PM +0800, Alice Guo (OSS) wrote:
> From: Ye Li <ye.li@xxxxxxx>
>
> Current driver may meet reconfigure failure caused by below reasons:
>
> 1. The wdog on iMX7ULP has different behavior after RCS valid. It needs
> to wait more than 2.5 wdog clock for clock sync before next
> reconfiguration, while imx8ulp wdog does not need such delay.
>
> 2. After unlock, there is 128 bus clock window opened for reconfiguration,
> but on iMX8ULP, the HW can't guarantee the latency. So it is possible
> the window is closed before the writing arrives to wdog.
>
> 3. If the PRES is enabled, the RCS valid time becomes x256 to the time
> of PRES disabled. It is about 1715ms on iMX8ULP. So We have to increase
> the RCS timeout and can't wait it in IRQ disabled.
>
> The patch updates the driver to handle failures
>
> 1. Using different wait for unlock and RCS. Unlock valid time is very short
> and only related to bus clock. It must be in IRQ disabled to avoid
> being interrupted in 128 clock window. But for RCS time, it is longer
> and ok for IRQ enabled.
>
> 2. Add retry for any reconfigure failure with default 5 times.
>
> 3. Add "fsl,imx8ulp-wdt" compatile string for iMX8ULP and afterwards
> platform which don't need more 2.5 wdog clock after RCS valid.
> For imx7ulp, add post delay of 2.5 clock after RCS valid.
>
> Signed-off-by: Ye Li <ye.li@xxxxxxx>
> Signed-off-by: Alice Guo <alice.guo@xxxxxxx>
> Reviewed-by: Jacky Bai <ping.bai@xxxxxxx>

Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>

> ---
>
> Changes for v2:
> - the wait timeout value of the RCS is 10ms, so use the sleep_us of
> readl_poll_timeout in imx7ulp_wdt_wait_rcs to avoid a 10ms hot wait
>
> drivers/watchdog/imx7ulp_wdt.c | 163 ++++++++++++++++++++++++++-------
> 1 file changed, 129 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/watchdog/imx7ulp_wdt.c b/drivers/watchdog/imx7ulp_wdt.c
> index 12715c248688..0cafa86fff7f 100644
> --- a/drivers/watchdog/imx7ulp_wdt.c
> +++ b/drivers/watchdog/imx7ulp_wdt.c
> @@ -14,7 +14,9 @@
> #include <linux/watchdog.h>
>
> #define WDOG_CS 0x0
> +#define WDOG_CS_FLG BIT(14)
> #define WDOG_CS_CMD32EN BIT(13)
> +#define WDOG_CS_PRES BIT(12)
> #define WDOG_CS_ULK BIT(11)
> #define WDOG_CS_RCS BIT(10)
> #define LPO_CLK 0x1
> @@ -39,7 +41,11 @@
> #define DEFAULT_TIMEOUT 60
> #define MAX_TIMEOUT 128
> #define WDOG_CLOCK_RATE 1000
> -#define WDOG_WAIT_TIMEOUT 10000
> +#define WDOG_ULK_WAIT_TIMEOUT 1000
> +#define WDOG_RCS_WAIT_TIMEOUT 10000
> +#define WDOG_RCS_POST_WAIT 3000
> +
> +#define RETRY_MAX 5
>
> static bool nowayout = WATCHDOG_NOWAYOUT;
> module_param(nowayout, bool, 0000);
> @@ -50,40 +56,82 @@ struct imx7ulp_wdt_device {
> struct watchdog_device wdd;
> void __iomem *base;
> struct clk *clk;
> + bool post_rcs_wait;
> };
>
> -static int imx7ulp_wdt_wait(void __iomem *base, u32 mask)
> +static int imx7ulp_wdt_wait_ulk(void __iomem *base)
> {
> u32 val = readl(base + WDOG_CS);
>
> - if (!(val & mask) && readl_poll_timeout_atomic(base + WDOG_CS, val,
> - val & mask, 0,
> - WDOG_WAIT_TIMEOUT))
> + if (!(val & WDOG_CS_ULK) &&
> + readl_poll_timeout_atomic(base + WDOG_CS, val,
> + val & WDOG_CS_ULK, 0,
> + WDOG_ULK_WAIT_TIMEOUT))
> return -ETIMEDOUT;
>
> return 0;
> }
>
> -static int imx7ulp_wdt_enable(struct watchdog_device *wdog, bool enable)
> +static int imx7ulp_wdt_wait_rcs(struct imx7ulp_wdt_device *wdt)
> {
> - struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog);
> + int ret = 0;
> + u32 val = readl(wdt->base + WDOG_CS);
> + u64 timeout = (val & WDOG_CS_PRES) ?
> + WDOG_RCS_WAIT_TIMEOUT * 256 : WDOG_RCS_WAIT_TIMEOUT;
> + unsigned long wait_min = (val & WDOG_CS_PRES) ?
> + WDOG_RCS_POST_WAIT * 256 : WDOG_RCS_POST_WAIT;
>
> + if (!(val & WDOG_CS_RCS) &&
> + readl_poll_timeout(wdt->base + WDOG_CS, val, val & WDOG_CS_RCS, 100,
> + timeout))
> + ret = -ETIMEDOUT;
> +
> + /* Wait 2.5 clocks after RCS done */
> + if (wdt->post_rcs_wait)
> + usleep_range(wait_min, wait_min + 2000);
> +
> + return ret;
> +}
> +
> +static int _imx7ulp_wdt_enable(struct imx7ulp_wdt_device *wdt, bool enable)
> +{
> u32 val = readl(wdt->base + WDOG_CS);
> int ret;
>
> local_irq_disable();
> writel(UNLOCK, wdt->base + WDOG_CNT);
> - ret = imx7ulp_wdt_wait(wdt->base, WDOG_CS_ULK);
> + ret = imx7ulp_wdt_wait_ulk(wdt->base);
> if (ret)
> goto enable_out;
> if (enable)
> writel(val | WDOG_CS_EN, wdt->base + WDOG_CS);
> else
> writel(val & ~WDOG_CS_EN, wdt->base + WDOG_CS);
> - ret = imx7ulp_wdt_wait(wdt->base, WDOG_CS_RCS);
> +
> + local_irq_enable();
> + ret = imx7ulp_wdt_wait_rcs(wdt);
> +
> + return ret;
>
> enable_out:
> local_irq_enable();
> + return ret;
> +}
> +
> +static int imx7ulp_wdt_enable(struct watchdog_device *wdog, bool enable)
> +{
> + struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog);
> + int ret;
> + u32 val;
> + u32 loop = RETRY_MAX;
> +
> + do {
> + ret = _imx7ulp_wdt_enable(wdt, enable);
> + val = readl(wdt->base + WDOG_CS);
> + } while (--loop > 0 && ((!!(val & WDOG_CS_EN)) != enable || ret));
> +
> + if (loop == 0)
> + return -EBUSY;
>
> return ret;
> }
> @@ -114,28 +162,44 @@ static int imx7ulp_wdt_stop(struct watchdog_device *wdog)
> return imx7ulp_wdt_enable(wdog, false);
> }
>
> -static int imx7ulp_wdt_set_timeout(struct watchdog_device *wdog,
> - unsigned int timeout)
> +static int _imx7ulp_wdt_set_timeout(struct imx7ulp_wdt_device *wdt,
> + unsigned int toval)
> {
> - struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog);
> - u32 val = WDOG_CLOCK_RATE * timeout;
> int ret;
>
> local_irq_disable();
> writel(UNLOCK, wdt->base + WDOG_CNT);
> - ret = imx7ulp_wdt_wait(wdt->base, WDOG_CS_ULK);
> + ret = imx7ulp_wdt_wait_ulk(wdt->base);
> if (ret)
> goto timeout_out;
> - writel(val, wdt->base + WDOG_TOVAL);
> - ret = imx7ulp_wdt_wait(wdt->base, WDOG_CS_RCS);
> - if (ret)
> - goto timeout_out;
> -
> - wdog->timeout = timeout;
> + writel(toval, wdt->base + WDOG_TOVAL);
> + local_irq_enable();
> + ret = imx7ulp_wdt_wait_rcs(wdt);
> + return ret;
>
> timeout_out:
> local_irq_enable();
> + return ret;
> +}
>
> +static int imx7ulp_wdt_set_timeout(struct watchdog_device *wdog,
> + unsigned int timeout)
> +{
> + struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog);
> + u32 toval = WDOG_CLOCK_RATE * timeout;
> + u32 val;
> + int ret;
> + u32 loop = RETRY_MAX;
> +
> + do {
> + ret = _imx7ulp_wdt_set_timeout(wdt, toval);
> + val = readl(wdt->base + WDOG_TOVAL);
> + } while (--loop > 0 && (val != toval || ret));
> +
> + if (loop == 0)
> + return -EBUSY;
> +
> + wdog->timeout = timeout;
> return ret;
> }
>
> @@ -175,38 +239,59 @@ static const struct watchdog_info imx7ulp_wdt_info = {
> WDIOF_MAGICCLOSE,
> };
>
> -static int imx7ulp_wdt_init(void __iomem *base, unsigned int timeout)
> +static int _imx7ulp_wdt_init(struct imx7ulp_wdt_device *wdt, unsigned int timeout, unsigned int cs)
> {
> u32 val;
> int ret;
>
> local_irq_disable();
>
> - val = readl(base + WDOG_CS);
> + val = readl(wdt->base + WDOG_CS);
> if (val & WDOG_CS_CMD32EN) {
> - writel(UNLOCK, base + WDOG_CNT);
> + writel(UNLOCK, wdt->base + WDOG_CNT);
> } else {
> mb();
> /* unlock the wdog for reconfiguration */
> - writel_relaxed(UNLOCK_SEQ0, base + WDOG_CNT);
> - writel_relaxed(UNLOCK_SEQ1, base + WDOG_CNT);
> + writel_relaxed(UNLOCK_SEQ0, wdt->base + WDOG_CNT);
> + writel_relaxed(UNLOCK_SEQ1, wdt->base + WDOG_CNT);
> mb();
> }
>
> - ret = imx7ulp_wdt_wait(base, WDOG_CS_ULK);
> + ret = imx7ulp_wdt_wait_ulk(wdt->base);
> if (ret)
> goto init_out;
>
> /* set an initial timeout value in TOVAL */
> - writel(timeout, base + WDOG_TOVAL);
> - /* enable 32bit command sequence and reconfigure */
> - val = WDOG_CS_CMD32EN | WDOG_CS_CLK | WDOG_CS_UPDATE |
> - WDOG_CS_WAIT | WDOG_CS_STOP;
> - writel(val, base + WDOG_CS);
> - imx7ulp_wdt_wait(base, WDOG_CS_RCS);
> + writel(timeout, wdt->base + WDOG_TOVAL);
> + writel(cs, wdt->base + WDOG_CS);
> + local_irq_enable();
> + ret = imx7ulp_wdt_wait_rcs(wdt);
> +
> + return ret;
>
> init_out:
> local_irq_enable();
> + return ret;
> +}
> +
> +static int imx7ulp_wdt_init(struct imx7ulp_wdt_device *wdt, unsigned int timeout)
> +{
> + /* enable 32bit command sequence and reconfigure */
> + u32 val = WDOG_CS_CMD32EN | WDOG_CS_CLK | WDOG_CS_UPDATE |
> + WDOG_CS_WAIT | WDOG_CS_STOP;
> + u32 cs, toval;
> + int ret;
> + u32 loop = RETRY_MAX;
> +
> + do {
> + ret = _imx7ulp_wdt_init(wdt, timeout, val);
> + toval = readl(wdt->base + WDOG_TOVAL);
> + cs = readl(wdt->base + WDOG_CS);
> + cs &= ~(WDOG_CS_FLG | WDOG_CS_ULK | WDOG_CS_RCS);
> + } while (--loop > 0 && (cs != val || toval != timeout || ret));
> +
> + if (loop == 0)
> + return -EBUSY;
>
> return ret;
> }
> @@ -239,6 +324,15 @@ static int imx7ulp_wdt_probe(struct platform_device *pdev)
> return PTR_ERR(imx7ulp_wdt->clk);
> }
>
> + imx7ulp_wdt->post_rcs_wait = true;
> + if (of_device_is_compatible(dev->of_node,
> + "fsl,imx8ulp-wdt")) {
> + dev_info(dev, "imx8ulp wdt probe\n");
> + imx7ulp_wdt->post_rcs_wait = false;
> + } else {
> + dev_info(dev, "imx7ulp wdt probe\n");
> + }
> +
> ret = clk_prepare_enable(imx7ulp_wdt->clk);
> if (ret)
> return ret;
> @@ -259,7 +353,7 @@ static int imx7ulp_wdt_probe(struct platform_device *pdev)
> watchdog_stop_on_reboot(wdog);
> watchdog_stop_on_unregister(wdog);
> watchdog_set_drvdata(wdog, imx7ulp_wdt);
> - ret = imx7ulp_wdt_init(imx7ulp_wdt->base, wdog->timeout * WDOG_CLOCK_RATE);
> + ret = imx7ulp_wdt_init(imx7ulp_wdt, wdog->timeout * WDOG_CLOCK_RATE);
> if (ret)
> return ret;
>
> @@ -289,7 +383,7 @@ static int __maybe_unused imx7ulp_wdt_resume_noirq(struct device *dev)
> return ret;
>
> if (imx7ulp_wdt_is_enabled(imx7ulp_wdt->base))
> - imx7ulp_wdt_init(imx7ulp_wdt->base, timeout);
> + imx7ulp_wdt_init(imx7ulp_wdt, timeout);
>
> if (watchdog_active(&imx7ulp_wdt->wdd))
> imx7ulp_wdt_start(&imx7ulp_wdt->wdd);
> @@ -303,6 +397,7 @@ static const struct dev_pm_ops imx7ulp_wdt_pm_ops = {
> };
>
> static const struct of_device_id imx7ulp_wdt_dt_ids[] = {
> + { .compatible = "fsl,imx8ulp-wdt", },
> { .compatible = "fsl,imx7ulp-wdt", },
> { /* sentinel */ }
> };
> --
> 2.17.1
>

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