Re: [04/13] watchdog: lantiq: access boot cause register through regmap

[Guenter Roeck <linux@xxxxxxxxxxxx>]

On Mon, Apr 17, 2017 at 09:29:33PM +0200, Hauke Mehrtens wrote:
> This patch avoids accessing the function ltq_reset_cause() and directly
> accesses the register given over the syscon interface. The syscon
> interface will be implemented for the xway SoCs for the falcon SoCs the
> ltq_reset_cause() function never worked, because a wrong offset was used.
> 
> Signed-off-by: Hauke Mehrtens <hauke@xxxxxxxxxx>

Acked-by: Guenter Roeck <linux@xxxxxxxxxxx>

> ---
>  drivers/watchdog/lantiq_wdt.c | 47 +++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 43 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/watchdog/lantiq_wdt.c b/drivers/watchdog/lantiq_wdt.c
> index e0823677d8c1..0e349ad03fdf 100644
> --- a/drivers/watchdog/lantiq_wdt.c
> +++ b/drivers/watchdog/lantiq_wdt.c
> @@ -17,9 +17,14 @@
>  #include <linux/uaccess.h>
>  #include <linux/clk.h>
>  #include <linux/io.h>
> +#include <linux/regmap.h>
> +#include <linux/mfd/syscon.h>
>  
>  #include <lantiq_soc.h>
>  
> +#define LTQ_RST_CAUSE_WDT_XRX		BIT(31)
> +#define LTQ_RST_CAUSE_WDT_FALCON	0x02
> +
>  /*
>   * Section 3.4 of the datasheet
>   * The password sequence protects the WDT control register from unintended
> @@ -186,6 +191,40 @@ static struct miscdevice ltq_wdt_miscdev = {
>  	.fops	= &ltq_wdt_fops,
>  };
>  
> +static void ltq_set_wdt_bootstatus(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct regmap *rcu_regmap;
> +	u32 status_reg_offset;
> +	u32 val;
> +	int err;
> +
> +	rcu_regmap = syscon_regmap_lookup_by_phandle(np,
> +						     "lantiq,rcu-syscon");
> +	if (IS_ERR_OR_NULL(rcu_regmap))
> +		return;
> +
> +	err = of_property_read_u32_index(np, "lantiq,rcu-syscon", 1,
> +					 &status_reg_offset);
> +	if (err) {
> +		dev_err(&pdev->dev, "Failed to get RCU reg offset\n");
> +		return;
> +	}
> +
> +	err = regmap_read(rcu_regmap, status_reg_offset, &val);
> +	if (err)
> +		return;
> +
> +	/* find out if the watchdog caused the last reboot */
> +	if (of_device_is_compatible(np, "lantiq,wdt-xrx100")) {
> +		if (val & LTQ_RST_CAUSE_WDT_XRX)
> +			ltq_wdt_bootstatus = WDIOF_CARDRESET;
> +	} else if  (of_device_is_compatible(np, "lantiq,wdt-falcon")) {
> +		if ((val & 0x7) == LTQ_RST_CAUSE_WDT_FALCON)
> +			ltq_wdt_bootstatus = WDIOF_CARDRESET;
> +	}
> +}
> +
>  static int
>  ltq_wdt_probe(struct platform_device *pdev)
>  {
> @@ -205,9 +244,7 @@ ltq_wdt_probe(struct platform_device *pdev)
>  	ltq_io_region_clk_rate = clk_get_rate(clk);
>  	clk_put(clk);
>  
> -	/* find out if the watchdog caused the last reboot */
> -	if (ltq_reset_cause() == LTQ_RST_CAUSE_WDTRST)
> -		ltq_wdt_bootstatus = WDIOF_CARDRESET;
> +	ltq_set_wdt_bootstatus(pdev);
>  
>  	dev_info(&pdev->dev, "Init done\n");
>  	return misc_register(&ltq_wdt_miscdev);
> @@ -222,7 +259,9 @@ ltq_wdt_remove(struct platform_device *pdev)
>  }
>  
>  static const struct of_device_id ltq_wdt_match[] = {
> -	{ .compatible = "lantiq,wdt" },
> +	{ .compatible = "lantiq,wdt"},
> +	{ .compatible = "lantiq,wdt-xrx100"},
> +	{ .compatible = "lantiq,wdt-falcon"},
>  	{},
>  };
>  MODULE_DEVICE_TABLE(of, ltq_wdt_match);