Re: [PATCH V4 3/3] watchdog: s3c2410_wdt: use syscon regmap interface to configure pmu register

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Hi Leela,

On Wednesday 30 of October 2013 15:21:13 Leela Krishna Amudala wrote:
> The syscon regmap interface is used to configure AUTOMATIC_WDT_RESET_DISABLE
> and MASK_WDT_RESET_REQUEST registers of PMU to mask/unmask enable/disable of
> watchdog in probe and s2r scenarios.
> 
> Signed-off-by: Leela Krishna Amudala <l.krishna@xxxxxxxxxxx>
> ---
>  .../devicetree/bindings/watchdog/samsung-wdt.txt   |   19 +++-
>  drivers/watchdog/s3c2410_wdt.c                     |  112 ++++++++++++++++++--
>  2 files changed, 122 insertions(+), 9 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/watchdog/samsung-wdt.txt b/Documentation/devicetree/bindings/watchdog/samsung-wdt.txt
> index 2aa486c..5a9889b 100644
> --- a/Documentation/devicetree/bindings/watchdog/samsung-wdt.txt
> +++ b/Documentation/devicetree/bindings/watchdog/samsung-wdt.txt
> @@ -5,10 +5,27 @@ after a preset amount of time during which the WDT reset event has not
>  occurred.
>  
>  Required properties:
> -- compatible : should be "samsung,s3c2410-wdt"
> +- compatible : should be one among the following
> +	(a) "samsung,s3c2410-wdt" for Exynos4 and previous SoCs
> +	(b) "samsung,exynos5250-wdt" for Exynos5250
> +	(c) "samsung,exynos5420-wdt" for Exynos5420
> +
>  - reg : base physical address of the controller and length of memory mapped
>  	region.
>  - interrupts : interrupt number to the cpu.
> +- samsung,pmusysreg : reference node to pmu sysreg (required only in case of Exynos5250 and 5420)

I don't really like the name of this property. Maybe
samsung,syscon-phandle would be better?

I'm not sure if this property should be tied to PMU, as on future SoCs
those registers might be located in another syscon-style IP. The
description should note that in case of Exynos 5250 and 5420 this should
point to the PMU node, though.

>  
>  Optional properties:
>  - timeout-sec : contains the watchdog timeout in seconds.
> +
> +Example:
> +
> +watchdog@101D0000 {
> +	compatible = "samsung,exynos5250-wdt";
> +	reg = <0x101D0000 0x100>;
> +	interrupts = <0 42 0>;
> +	clocks = <&clock 336>;
> +	clock-names = "watchdog";
> +	samsung,sysreg = <&pmu_sys_reg>;
> +	status = "okay";
> +};
> diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
> index 23aad7c..d8aefef 100644
> --- a/drivers/watchdog/s3c2410_wdt.c
> +++ b/drivers/watchdog/s3c2410_wdt.c
> @@ -41,6 +41,8 @@
>  #include <linux/slab.h>
>  #include <linux/err.h>
>  #include <linux/of.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/regmap.h>
>  
>  #define S3C2410_WTCON		0x00
>  #define S3C2410_WTDAT		0x04
> @@ -61,6 +63,10 @@
>  #define CONFIG_S3C2410_WATCHDOG_ATBOOT		(0)
>  #define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME	(15)
>  
> +#define WDT_DISABLE_REG_OFFSET		0x0408
> +#define WDT_MASK_RESET_REG_OFFSET	0x040c
> +#define QUIRK_NEEDS_PMU_CONFIG		(1 << 0)
> +
>  static bool nowayout	= WATCHDOG_NOWAYOUT;
>  static int tmr_margin;
>  static int tmr_atboot	= CONFIG_S3C2410_WATCHDOG_ATBOOT;
> @@ -84,6 +90,12 @@ MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, "
>  			"0 to reboot (default 0)");
>  MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug (default 0)");
>  
> +struct pmu_config {

For the sake of future extensibility I'd rename this struct to
s3c2410_wdt_variant and add an u32 quirks field, which would has
the QUIRK_NEEDS_PMU_CONFIG set for 5250 and 5420 variants.

> +	int	disable_reg;
> +	int	mask_reset_reg;
> +	int	mask_bit;
> +};
> +
>  struct s3c2410_wdt {
>  	struct device		*dev;
>  	struct clk		*clock;
> @@ -94,7 +106,34 @@ struct s3c2410_wdt {
>  	unsigned long		wtdat_save;
>  	struct watchdog_device	wdt_device;
>  	struct notifier_block	freq_transition;
> +	struct pmu_config	*wdt_pmu_config;
> +	struct regmap		*pmureg;
> +	unsigned int		quirks;

Quirks should be a static per-variant property.

> +};
> +
> +#ifdef CONFIG_OF
> +static struct pmu_config pmu_config_5250  = {
> +	.disable_reg = WDT_DISABLE_REG_OFFSET,
> +	.mask_reset_reg = WDT_MASK_RESET_REG_OFFSET,
> +	.mask_bit = 20
> +};
> +
> +static struct pmu_config pmu_config_5420 = {
> +	.disable_reg = WDT_DISABLE_REG_OFFSET,
> +	.mask_reset_reg = WDT_MASK_RESET_REG_OFFSET,
> +	.mask_bit = 0
> +};
> +
> +static const struct of_device_id s3c2410_wdt_match[] = {
> +	{ .compatible = "samsung,s3c2410-wdt" },

If you follow what I suggested above, the basic variant would also have
a variant struct associated with it, which would be more consistent.

> +	{ .compatible = "samsung,exynos5250-wdt",
> +	  .data = (struct pmu_config *) &pmu_config_5250 },
> +	{ .compatible = "samsung,exynos5420-wdt",
> +	  .data = (struct pmu_config *) &pmu_config_5420 },
> +	{},
>  };
> +MODULE_DEVICE_TABLE(of, s3c2410_wdt_match);
> +#endif
>  
>  /* watchdog control routines */
>  
> @@ -111,6 +150,38 @@ static inline struct s3c2410_wdt *freq_to_wdt(struct notifier_block *nb)
>  	return container_of(nb, struct s3c2410_wdt, freq_transition);
>  }
>  
> +static void s3c2410wdt_mask_and_disable_reset(int mask, struct s3c2410_wdt *wdt)
> +{
> +	unsigned int disable, mask_reset;
> +	int ret;
> +
> +	ret = regmap_read(wdt->pmureg, wdt->wdt_pmu_config->disable_reg,
> +								&disable);
> +	if (ret < 0) {
> +		dev_err(wdt->dev, "failed to read disable reg(%d)\n", ret);
> +		return;
> +	}
> +
> +	ret = regmap_read(wdt->pmureg, wdt->wdt_pmu_config->mask_reset_reg,
> +								&mask_reset);
> +	if (ret < 0) {
> +		dev_err(wdt->dev, "failed to read mask reset reg(%d)\n", ret);
> +		return;
> +	}
> +
> +	if (mask) {
> +		disable |= (1 << wdt->wdt_pmu_config->mask_bit);
> +		mask_reset |= (1 << wdt->wdt_pmu_config->mask_bit);
> +	} else {
> +		disable &= ~(1 << wdt->wdt_pmu_config->mask_bit);
> +		mask_reset &= ~(1 << wdt->wdt_pmu_config->mask_bit);
> +	}
> +
> +	regmap_write(wdt->pmureg, wdt->wdt_pmu_config->disable_reg, disable);
> +	regmap_write(wdt->pmureg, wdt->wdt_pmu_config->mask_reset_reg,
> +								mask_reset);

I believe you can (and on some SoCs even have to, due to other bits in the
registers being used for other purposes) use regmap_update_bits() for
read-modify-write sequences above.

> +}
> +
>  static int s3c2410wdt_keepalive(struct watchdog_device *wdd)
>  {
>  	struct s3c2410_wdt *wdt = watchdog_get_drvdata(wdd);
> @@ -332,6 +403,14 @@ static inline void s3c2410wdt_cpufreq_deregister(struct s3c2410_wdt *wdt)
>  }
>  #endif
>  
> +/* s3c2410_get_wdt_driver_data */
> +static inline unsigned int get_wdt_driver_data(struct platform_device *pdev)
> +{
> +	const struct of_device_id *match;
> +	match = of_match_node(s3c2410_wdt_match, pdev->dev.of_node);
> +	return (unsigned int)match->data;

Why do you need this cast? I believe this function should simply return
(const struct pmu_config *) or (const struct s3c2410_wdt_variant *) when
my comments above get addressed.

> +}
> +
>  static int s3c2410wdt_probe(struct platform_device *pdev)
>  {
>  	struct device *dev;
> @@ -354,6 +433,17 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
>  	spin_lock_init(&wdt->lock);
>  	wdt->wdt_device = s3c2410_wdd;
>  
> +	wdt->pmureg = syscon_regmap_lookup_by_phandle(dev->of_node,
> +						"samsung,pmusysreg");
> +	if (IS_ERR(wdt->pmureg)) {
> +		dev_err(dev, "syscon regmap lookup failed.\n");
> +		return PTR_ERR(wdt->pmureg);
> +	}

This should be performed only if given variant has the
QUIRK_NEEDS_PMU_CONFIG flag set in its variant data. Otherwise you don't
have any distinction between cases when PMU is not needed (and so
unspecified) and PMU is needed, but unspecified.

> +
> +	wdt->wdt_pmu_config = (struct pmu_config *) get_wdt_driver_data(pdev);
> +	if (wdt->wdt_pmu_config)
> +		wdt->quirks = QUIRK_NEEDS_PMU_CONFIG;

See my comment on quirks above.

> +
>  	wdt_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
>  	if (wdt_irq == NULL) {
>  		dev_err(dev, "no irq resource specified\n");
> @@ -444,6 +534,8 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
>  		 (wtcon & S3C2410_WTCON_RSTEN) ? "en" : "dis",
>  		 (wtcon & S3C2410_WTCON_INTEN) ? "en" : "dis");
>  
> +	if (wdt->quirks & QUIRK_NEEDS_PMU_CONFIG)
> +		s3c2410wdt_mask_and_disable_reset(0, wdt);

nit: Blank line here would be nice.

Best regards,
Tomasz

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