[PATCH v3 1/3] watchdog: imx2_wdg: suspend watchdog in WAIT mode

[Guenter Roeck]

On Thu, Nov 03, 2022 at 11:03:56AM +0100, Andrej Picej wrote:
> Putting device into the "Suspend-To-Idle" mode causes watchdog to
> trigger and resets the board after set watchdog timeout period elapses.
> 
> Introduce new device-tree property "fsl,suspend-in-wait" which suspends
> watchdog in WAIT mode. This is done by setting WDW bit in WCR
> (Watchdog Control Register). Watchdog operation is restored after
> exiting WAIT mode as expected. WAIT mode corresponds with Linux's
> "Suspend-To-Idle".
> 
> Signed-off-by: Andrej Picej <andrej.picej at norik.com>
> Reviewed-by: Fabio Estevam <festevam at gmail.com>

For my reference:

Reviewed-by: Guenter Roeck <linux at roeck-us.net>

This will have to wait for dt approval.

Thanks,
Guenter

> ---
> Changes in v3:
>  - fix spelling in commit message,
>  - fix and simplify property handling in probe,
>  - add a comment about unknown interaction between imx7d no-ping
>    functionality and "fsl,suspend-in-wait",
>  - property support handled by of_device_id data pointer.
> 
> Changes in v2:
>  - validate the property with compatible string, as this functionality
>    is not supported by all devices.
> ---
>  drivers/watchdog/imx2_wdt.c | 55 +++++++++++++++++++++++++++++++++++--
>  1 file changed, 52 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
> index d0c5d47ddede..19ab7b3d286b 100644
> --- a/drivers/watchdog/imx2_wdt.c
> +++ b/drivers/watchdog/imx2_wdt.c
> @@ -27,6 +27,7 @@
>  #include <linux/module.h>
>  #include <linux/moduleparam.h>
>  #include <linux/of_address.h>
> +#include <linux/of_device.h>
>  #include <linux/platform_device.h>
>  #include <linux/regmap.h>
>  #include <linux/watchdog.h>
> @@ -35,6 +36,7 @@
>  
>  #define IMX2_WDT_WCR		0x00		/* Control Register */
>  #define IMX2_WDT_WCR_WT		(0xFF << 8)	/* -> Watchdog Timeout Field */
> +#define IMX2_WDT_WCR_WDW	BIT(7)		/* -> Watchdog disable for WAIT */
>  #define IMX2_WDT_WCR_WDA	BIT(5)		/* -> External Reset WDOG_B */
>  #define IMX2_WDT_WCR_SRS	BIT(4)		/* -> Software Reset Signal */
>  #define IMX2_WDT_WCR_WRE	BIT(3)		/* -> WDOG Reset Enable */
> @@ -60,13 +62,19 @@
>  
>  #define WDOG_SEC_TO_COUNT(s)	((s * 2 - 1) << 8)
>  
> +struct imx2_wdt_data {
> +	bool wdw_supported;
> +};
> +
>  struct imx2_wdt_device {
>  	struct clk *clk;
>  	struct regmap *regmap;
>  	struct watchdog_device wdog;
> +	const struct imx2_wdt_data *data;
>  	bool ext_reset;
>  	bool clk_is_on;
>  	bool no_ping;
> +	bool sleep_wait;
>  };
>  
>  static bool nowayout = WATCHDOG_NOWAYOUT;
> @@ -129,6 +137,9 @@ static inline void imx2_wdt_setup(struct watchdog_device *wdog)
>  
>  	/* Suspend timer in low power mode, write once-only */
>  	val |= IMX2_WDT_WCR_WDZST;
> +	/* Suspend timer in low power WAIT mode, write once-only */
> +	if (wdev->sleep_wait)
> +		val |= IMX2_WDT_WCR_WDW;
>  	/* Strip the old watchdog Time-Out value */
>  	val &= ~IMX2_WDT_WCR_WT;
>  	/* Generate internal chip-level reset if WDOG times out */
> @@ -292,6 +303,8 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)
>  	wdog->max_hw_heartbeat_ms = IMX2_WDT_MAX_TIME * 1000;
>  	wdog->parent		= dev;
>  
> +	wdev->data = of_device_get_match_data(dev);
> +
>  	ret = platform_get_irq(pdev, 0);
>  	if (ret > 0)
>  		if (!devm_request_irq(dev, ret, imx2_wdt_isr, 0,
> @@ -313,9 +326,18 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)
>  
>  	wdev->ext_reset = of_property_read_bool(dev->of_node,
>  						"fsl,ext-reset-output");
> +
> +	if (of_property_read_bool(dev->of_node, "fsl,suspend-in-wait")) {
> +		if (!wdev->data->wdw_supported) {
> +			dev_err(dev, "suspend-in-wait not supported\n");
> +			return -EINVAL;
> +		}
> +		wdev->sleep_wait = true;
> +	}
> +
>  	/*
>  	 * The i.MX7D doesn't support low power mode, so we need to ping the watchdog
> -	 * during suspend.
> +	 * during suspend. Interaction with "fsl,suspend-in-wait" is unknown!
>  	 */
>  	wdev->no_ping = !of_device_is_compatible(dev->of_node, "fsl,imx7d-wdt");
>  	platform_set_drvdata(pdev, wdog);
> @@ -417,9 +439,36 @@ static int __maybe_unused imx2_wdt_resume(struct device *dev)
>  static SIMPLE_DEV_PM_OPS(imx2_wdt_pm_ops, imx2_wdt_suspend,
>  			 imx2_wdt_resume);
>  
> +struct imx2_wdt_data imx_wdt = {
> +	.wdw_supported = true,
> +};
> +
> +struct imx2_wdt_data imx_wdt_legacy = {
> +	.wdw_supported = false,
> +};
> +
>  static const struct of_device_id imx2_wdt_dt_ids[] = {
> -	{ .compatible = "fsl,imx21-wdt", },
> -	{ .compatible = "fsl,imx7d-wdt", },
> +	{ .compatible = "fsl,imx21-wdt", .data = &imx_wdt_legacy },
> +	{ .compatible = "fsl,imx25-wdt", .data = &imx_wdt },
> +	{ .compatible = "fsl,imx27-wdt", .data = &imx_wdt_legacy },
> +	{ .compatible = "fsl,imx31-wdt", .data = &imx_wdt_legacy },
> +	{ .compatible = "fsl,imx35-wdt", .data = &imx_wdt },
> +	{ .compatible = "fsl,imx50-wdt", .data = &imx_wdt },
> +	{ .compatible = "fsl,imx51-wdt", .data = &imx_wdt },
> +	{ .compatible = "fsl,imx53-wdt", .data = &imx_wdt },
> +	{ .compatible = "fsl,imx6q-wdt", .data = &imx_wdt },
> +	{ .compatible = "fsl,imx6sl-wdt", .data = &imx_wdt },
> +	{ .compatible = "fsl,imx6sll-wdt", .data = &imx_wdt },
> +	{ .compatible = "fsl,imx6sx-wdt", .data = &imx_wdt },
> +	{ .compatible = "fsl,imx6ul-wdt", .data = &imx_wdt },
> +	{ .compatible = "fsl,imx7d-wdt", .data = &imx_wdt },
> +	{ .compatible = "fsl,imx8mm-wdt", .data = &imx_wdt },
> +	{ .compatible = "fsl,imx8mn-wdt", .data = &imx_wdt },
> +	{ .compatible = "fsl,imx8mp-wdt", .data = &imx_wdt },
> +	{ .compatible = "fsl,imx8mq-wdt", .data = &imx_wdt },
> +	{ .compatible = "fsl,ls1012a-wdt", .data = &imx_wdt_legacy },
> +	{ .compatible = "fsl,ls1043a-wdt", .data = &imx_wdt_legacy },
> +	{ .compatible = "fsl,vf610-wdt", .data = &imx_wdt },
>  	{ /* sentinel */ }
>  };
>  MODULE_DEVICE_TABLE(of, imx2_wdt_dt_ids);
> -- 
> 2.25.1
>