[PATCH v1] watchdog: imx2: fix hang-up on boot for i.MX21, i.MX27 and i.MX31 SoCs

[Guenter Roeck]

On 12/10/2016 05:06 PM, Vladimir Zapolskiy wrote:
> Power down counter enable/disable bit switch is located in WMCR
> register, but watchdog controllers found on legacy i.MX21, i.MX27 and
> i.MX31 SoCs don't have this register. As a result of writing data to
> the non-existing register on driver probe the SoC hangs up, to fix the
> problem add more OF compatible strings and on this basis get
> information about availability of the WMCR register.
>
> Fixes: 5fe65ce7ccbb ("watchdog: imx2_wdt: Disable power down counter on boot")
> Signed-off-by: Vladimir Zapolskiy <vz at mleia.com>

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

> ---
> Changes from RFC to v1:
> * replaced private data struct with a macro as suggested by Guenter,
> * updated the comment in the source code to reflect the change,
> * rearranged and simplified the logic of detecting WMCR presence,
> * pulled the fix out from the series with optional proposed DTS changes.
>
>  drivers/watchdog/imx2_wdt.c | 30 +++++++++++++++++++++++++-----
>  1 file changed, 25 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
> index 4874b0f..66bd454 100644
> --- a/drivers/watchdog/imx2_wdt.c
> +++ b/drivers/watchdog/imx2_wdt.c
> @@ -30,6 +30,7 @@
>  #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>
> @@ -57,6 +58,7 @@
>  #define IMX2_WDT_WICR_WICT	0xFF		/* -> Interrupt Count Timeout */
>
>  #define IMX2_WDT_WMCR		0x08		/* Misc Register */
> +#define IMX2_WDT_NO_WMCR	((void *)true)	/* Indicates unavailable WMCR */
>
>  #define IMX2_WDT_MAX_TIME	128
>  #define IMX2_WDT_DEFAULT_TIME	60		/* in seconds */
> @@ -70,6 +72,8 @@ struct imx2_wdt_device {
>  	bool ext_reset;
>  };
>
> +static const struct of_device_id imx2_wdt_dt_ids[];
> +
>  static bool nowayout = WATCHDOG_NOWAYOUT;
>  module_param(nowayout, bool, 0);
>  MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
> @@ -242,6 +246,7 @@ static const struct regmap_config imx2_wdt_regmap_config = {
>
>  static int __init imx2_wdt_probe(struct platform_device *pdev)
>  {
> +	const struct of_device_id *of_id;
>  	struct imx2_wdt_device *wdev;
>  	struct watchdog_device *wdog;
>  	struct resource *res;
> @@ -310,11 +315,13 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)
>  	}
>
>  	/*
> -	 * Disable the watchdog power down counter at boot. Otherwise the power
> -	 * down counter will pull down the #WDOG interrupt line for one clock
> -	 * cycle.
> +	 * If watchdog controller has WMCR, disable the watchdog power
> +	 * down counter at boot. Otherwise the power down counter will
> +	 * pull down the #WDOG interrupt line for one clock cycle.
>  	 */
> -	regmap_write(wdev->regmap, IMX2_WDT_WMCR, 0);
> +	of_id = of_match_device(imx2_wdt_dt_ids, &pdev->dev);
> +	if (of_id && !of_id->data)
> +		regmap_write(wdev->regmap, IMX2_WDT_WMCR, 0);
>
>  	ret = watchdog_register_device(wdog);
>  	if (ret) {
> @@ -412,7 +419,20 @@ static SIMPLE_DEV_PM_OPS(imx2_wdt_pm_ops, imx2_wdt_suspend,
>  			 imx2_wdt_resume);
>
>  static const struct of_device_id imx2_wdt_dt_ids[] = {
> -	{ .compatible = "fsl,imx21-wdt", },
> +	{ .compatible = "fsl,imx21-wdt", .data = IMX2_WDT_NO_WMCR },
> +	{ .compatible = "fsl,imx25-wdt",  },
> +	{ .compatible = "fsl,imx27-wdt", .data = IMX2_WDT_NO_WMCR },
> +	{ .compatible = "fsl,imx31-wdt", .data = IMX2_WDT_NO_WMCR },
> +	{ .compatible = "fsl,imx35-wdt",  },
> +	{ .compatible = "fsl,imx50-wdt",  },
> +	{ .compatible = "fsl,imx51-wdt",  },
> +	{ .compatible = "fsl,imx53-wdt",  },
> +	{ .compatible = "fsl,imx6q-wdt",  },
> +	{ .compatible = "fsl,imx6sl-wdt", },
> +	{ .compatible = "fsl,imx6sx-wdt", },
> +	{ .compatible = "fsl,imx6ul-wdt", },
> +	{ .compatible = "fsl,imx7d-wdt",  },
> +	{ .compatible = "fsl,vf610-wdt",  },
>  	{ /* sentinel */ }
>  };
>  MODULE_DEVICE_TABLE(of, imx2_wdt_dt_ids);
>