Re: [PATCH V9 2/3] watchdog: s3c2410_wdt: use syscon regmap interface to configure pmu register

[Guenter Roeck <linux@roeck-us.net>]

On 11/18/2013 08:36 PM, Leela Krishna Amudala wrote:
> Hi Guenter Roeck,
>
> Thanks for reviewing the patch.
>
>
> On Mon, Nov 18, 2013 at 10:12 PM, Guenter Roeck <linux@roeck-us.net> wrote:
>> On Mon, Nov 18, 2013 at 03:19:48PM +0530, Leela Krishna Amudala wrote:
>>> Add device tree support for exynos5250 and 5420 SoCs and use syscon regmap interface
>>> 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@samsung.com>
>>> ---
>>>   .../devicetree/bindings/watchdog/samsung-wdt.txt   |   21 ++-
>>>   drivers/watchdog/Kconfig                           |    1 +
>>>   drivers/watchdog/s3c2410_wdt.c                     |  145 ++++++++++++++++++--
>>>   3 files changed, 157 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/watchdog/samsung-wdt.txt b/Documentation/devicetree/bindings/watchdog/samsung-wdt.txt
>>> index 2aa486c..5dea363 100644
>>> --- a/Documentation/devicetree/bindings/watchdog/samsung-wdt.txt
>>> +++ b/Documentation/devicetree/bindings/watchdog/samsung-wdt.txt
>>> @@ -5,10 +5,29 @@ 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,syscon-phandle : reference to syscon node (This property required only
>>> +     in case of compatible being "samsung,exynos5250-wdt" or "samsung,exynos5420-wdt".
>>> +     In case of Exynos5250 and 5420 this property points to syscon node holding the PMU
>>> +     base address)
>>>
>>>   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,syscon-phandle = <&pmu_sys_reg>;
>>> +};
>>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>>> index d1d53f3..0d272ae 100644
>>> --- a/drivers/watchdog/Kconfig
>>> +++ b/drivers/watchdog/Kconfig
>>> @@ -188,6 +188,7 @@ config S3C2410_WATCHDOG
>>>        tristate "S3C2410 Watchdog"
>>>        depends on HAVE_S3C2410_WATCHDOG
>>>        select WATCHDOG_CORE
>>> +     select MFD_SYSCON if ARCH_EXYNOS5
>>>        help
>>>          Watchdog timer block in the Samsung SoCs. This will reboot
>>>          the system when the timer expires with the watchdog enabled.
>>> diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
>>> index 23aad7c..42e0fd3 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 +90,13 @@ 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 s3c2410_wdt_variant {
>>> +     int disable_reg;
>>> +     int mask_reset_reg;
>>> +     int mask_bit;
>>> +     u32 quirks;
>>> +};
>>> +
>>>   struct s3c2410_wdt {
>>>        struct device           *dev;
>>>        struct clk              *clock;
>>> @@ -94,7 +107,49 @@ struct s3c2410_wdt {
>>>        unsigned long           wtdat_save;
>>>        struct watchdog_device  wdt_device;
>>>        struct notifier_block   freq_transition;
>>> +     struct s3c2410_wdt_variant *drv_data;
>>> +     struct regmap *pmureg;
>>> +};
>>> +
>>> +static const struct s3c2410_wdt_variant drv_data_s3c2410 = {
>>> +     .quirks = 0
>>> +};
>>> +
>>> +#ifdef CONFIG_OF
>>> +static const struct s3c2410_wdt_variant drv_data_exynos5250  = {
>>> +     .disable_reg = WDT_DISABLE_REG_OFFSET,
>>> +     .mask_reset_reg = WDT_MASK_RESET_REG_OFFSET,
>>> +     .mask_bit = 20,
>>> +     .quirks = QUIRK_NEEDS_PMU_CONFIG
>>> +};
>>> +
>>> +static const struct s3c2410_wdt_variant drv_data_exynos5420 = {
>>> +     .disable_reg = WDT_DISABLE_REG_OFFSET,
>>> +     .mask_reset_reg = WDT_MASK_RESET_REG_OFFSET,
>>> +     .mask_bit = 0,
>>> +     .quirks = QUIRK_NEEDS_PMU_CONFIG
>>> +};
>>> +
>>> +static const struct of_device_id s3c2410_wdt_match[] = {
>>> +     { .compatible = "samsung,s3c2410-wdt",
>>> +       .data = &drv_data_s3c2410 },
>>> +     { .compatible = "samsung,exynos5250-wdt",
>>> +       .data = &drv_data_exynos5250 },
>>> +     { .compatible = "samsung,exynos5420-wdt",
>>> +       .data = &drv_data_exynos5420 },
>>> +     {},
>>>   };
>>> +MODULE_DEVICE_TABLE(of, s3c2410_wdt_match);
>>> +#endif
>>> +
>>> +static const struct platform_device_id s3c2410_wdt_ids[] = {
>>> +     {
>>> +             .name = "s3c2410-wdt",
>>> +             .driver_data = (unsigned long)&drv_data_s3c2410,
>>> +     },
>>> +     {}
>>> +};
>>> +MODULE_DEVICE_TABLE(platform, s3c2410_wdt_ids);
>>>
>>>   /* watchdog control routines */
>>>
>>> @@ -111,6 +166,26 @@ static inline struct s3c2410_wdt *freq_to_wdt(struct notifier_block *nb)
>>>        return container_of(nb, struct s3c2410_wdt, freq_transition);
>>>   }
>>>
>>> +static int s3c2410wdt_mask_and_disable_reset(struct s3c2410_wdt *wdt, bool mask)
>>> +{
>>> +     int ret;
>>> +     u32 mask_val = 1 << wdt->drv_data->mask_bit;
>>> +     u32 val = 0;
>>> +
>>> +     if (mask)
>>> +             val = mask_val;
>>> +
>>> +     ret = regmap_update_bits(wdt->pmureg,
>>> +                     wdt->drv_data->disable_reg,
>>> +                     mask_val, val);
>>> +     if (ret < 0)
>>> +             return ret;
>>> +
>>> +     return regmap_update_bits(wdt->pmureg,
>>> +                     wdt->drv_data->mask_reset_reg,
>>> +                     mask_val, val);
>>> +}
>>> +
>>>   static int s3c2410wdt_keepalive(struct watchdog_device *wdd)
>>>   {
>>>        struct s3c2410_wdt *wdt = watchdog_get_drvdata(wdd);
>>> @@ -332,6 +407,20 @@ static inline void s3c2410wdt_cpufreq_deregister(struct s3c2410_wdt *wdt)
>>>   }
>>>   #endif
>>>
>>> +/* s3c2410_get_wdt_driver_data */
>>> +static inline struct s3c2410_wdt_variant *
>>> +get_wdt_drv_data(struct platform_device *pdev)
>>> +{
>>> +     if (pdev->dev.of_node) {
>>> +             const struct of_device_id *match;
>>> +             match = of_match_node(s3c2410_wdt_match, pdev->dev.of_node);
>>> +             return (struct s3c2410_wdt_variant *)match->data;
>>> +     } else {
>>> +             return (struct s3c2410_wdt_variant *)
>>> +                     platform_get_device_id(pdev)->driver_data;
>>> +     }
>>> +}
>>> +
>>>   static int s3c2410wdt_probe(struct platform_device *pdev)
>>>   {
>>>        struct device *dev;
>>> @@ -354,6 +443,16 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
>>>        spin_lock_init(&wdt->lock);
>>>        wdt->wdt_device = s3c2410_wdd;
>>>
>>> +     wdt->drv_data = get_wdt_drv_data(pdev);
>>> +     if (wdt->drv_data->quirks & QUIRK_NEEDS_PMU_CONFIG) {
>>> +             wdt->pmureg = syscon_regmap_lookup_by_phandle(dev->of_node,
>>> +                                                     "samsung,syscon-phandle");
>>> +             if (IS_ERR(wdt->pmureg)) {
>>> +                     dev_err(dev, "syscon regmap lookup failed.\n");
>>> +                     return PTR_ERR(wdt->pmureg);
>>> +             }
>>> +     }
>>> +
>>>        wdt_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
>>>        if (wdt_irq == NULL) {
>>>                dev_err(dev, "no irq resource specified\n");
>>> @@ -444,6 +543,14 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
>>>                 (wtcon & S3C2410_WTCON_RSTEN) ? "en" : "dis",
>>>                 (wtcon & S3C2410_WTCON_INTEN) ? "en" : "dis");
>>>
>>> +     if (wdt->drv_data->quirks & QUIRK_NEEDS_PMU_CONFIG) {
>>> +             ret = s3c2410wdt_mask_and_disable_reset(wdt, false);
>>> +             if (ret < 0) {
>>> +                     dev_err(wdt->dev, "failed to update pmu register");
>>
>> Hmm ... still not happy ;-). This message is the same for each call
>> to s3c2410wdt_mask_and_disable_reset(). Why not create it there ?
>> Sure, you'd have to decide if you want to use dev_warn() or dev_err(),
>> but that would still be better than repeating the same message (and code)
>> five times.
>>
>> The same is true for the if() statement. It might be worthwhile calling
>> s3c2410wdt_mask_and_disable_reset() unconditionally and adding something
>> like
>>
>>          if (!(wdt->drv_data->quirks & QUIRK_NEEDS_PMU_CONFIG))
>>                  return 0;
>>
>> to it.
>>
>
> As Tomasz Figa suggested I handled the error conditions here
> Please go through this link for your reference
> https://patchwork.kernel.org/patch/3118771/
>

His proposed function had the error message in the function,
so I am not entirely following your logic.

He said you should _handle_ the error condition in the calling code.
Dumping an error message and doing nothing isn't really "handling"
the error condition.

Guenter

> Best Wishes,
> Leela Krishna.
>
>> Thanks,
>> Guenter
>>
>>> +                     goto err_cpufreq;
>>> +             }
>>> +     }
>>> +
>>>        return 0;
>>>
>>>    err_cpufreq:
>>> @@ -459,8 +566,15 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
>>>
>>>   static int s3c2410wdt_remove(struct platform_device *dev)
>>>   {
>>> +     int ret;
>>>        struct s3c2410_wdt *wdt = platform_get_drvdata(dev);
>>>
>>> +     if (wdt->drv_data->quirks & QUIRK_NEEDS_PMU_CONFIG) {
>>> +             ret = s3c2410wdt_mask_and_disable_reset(wdt, true);
>>> +             if (ret < 0)
>>> +                     dev_warn(wdt->dev, "failed to update pmu register");
>>> +     }
>>> +
>>>        watchdog_unregister_device(&wdt->wdt_device);
>>>
>>>        s3c2410wdt_cpufreq_deregister(wdt);
>>> @@ -473,8 +587,15 @@ static int s3c2410wdt_remove(struct platform_device *dev)
>>>
>>>   static void s3c2410wdt_shutdown(struct platform_device *dev)
>>>   {
>>> +     int ret;
>>>        struct s3c2410_wdt *wdt = platform_get_drvdata(dev);
>>>
>>> +     if (wdt->drv_data->quirks & QUIRK_NEEDS_PMU_CONFIG) {
>>> +             ret = s3c2410wdt_mask_and_disable_reset(wdt, true);
>>> +             if (ret < 0)
>>> +                     dev_warn(wdt->dev, "failed to update pmu register");
>>> +     }
>>> +
>>>        s3c2410wdt_stop(&wdt->wdt_device);
>>>   }
>>>
>>> @@ -482,12 +603,19 @@ static void s3c2410wdt_shutdown(struct platform_device *dev)
>>>
>>>   static int s3c2410wdt_suspend(struct device *dev)
>>>   {
>>> +     int ret;
>>>        struct s3c2410_wdt *wdt = dev_get_drvdata(dev);
>>>
>>>        /* Save watchdog state, and turn it off. */
>>>        wdt->wtcon_save = readl(wdt->reg_base + S3C2410_WTCON);
>>>        wdt->wtdat_save = readl(wdt->reg_base + S3C2410_WTDAT);
>>>
>>> +     if (wdt->drv_data->quirks & QUIRK_NEEDS_PMU_CONFIG) {
>>> +             ret = s3c2410wdt_mask_and_disable_reset(wdt, true);
>>> +             if (ret < 0)
>>> +                     dev_warn(wdt->dev, "failed to update pmu register");
>>> +     }
>>> +
>>>        /* Note that WTCNT doesn't need to be saved. */
>>>        s3c2410wdt_stop(&wdt->wdt_device);
>>>
>>> @@ -496,6 +624,7 @@ static int s3c2410wdt_suspend(struct device *dev)
>>>
>>>   static int s3c2410wdt_resume(struct device *dev)
>>>   {
>>> +     int ret;
>>>        struct s3c2410_wdt *wdt = dev_get_drvdata(dev);
>>>
>>>        /* Restore watchdog state. */
>>> @@ -503,6 +632,12 @@ static int s3c2410wdt_resume(struct device *dev)
>>>        writel(wdt->wtdat_save, wdt->reg_base + S3C2410_WTCNT);/* Reset count */
>>>        writel(wdt->wtcon_save, wdt->reg_base + S3C2410_WTCON);
>>>
>>> +     if (wdt->drv_data->quirks & QUIRK_NEEDS_PMU_CONFIG) {
>>> +             ret = s3c2410wdt_mask_and_disable_reset(wdt, false);
>>> +             if (ret < 0)
>>> +                     dev_warn(wdt->dev, "failed to update pmu register");
>>> +     }
>>> +
>>>        dev_info(dev, "watchdog %sabled\n",
>>>                (wdt->wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");
>>>
>>> @@ -513,18 +648,11 @@ static int s3c2410wdt_resume(struct device *dev)
>>>   static SIMPLE_DEV_PM_OPS(s3c2410wdt_pm_ops, s3c2410wdt_suspend,
>>>                        s3c2410wdt_resume);
>>>
>>> -#ifdef CONFIG_OF
>>> -static const struct of_device_id s3c2410_wdt_match[] = {
>>> -     { .compatible = "samsung,s3c2410-wdt" },
>>> -     {},
>>> -};
>>> -MODULE_DEVICE_TABLE(of, s3c2410_wdt_match);
>>> -#endif
>>> -
>>>   static struct platform_driver s3c2410wdt_driver = {
>>>        .probe          = s3c2410wdt_probe,
>>>        .remove         = s3c2410wdt_remove,
>>>        .shutdown       = s3c2410wdt_shutdown,
>>> +     .id_table       = s3c2410_wdt_ids,
>>>        .driver         = {
>>>                .owner  = THIS_MODULE,
>>>                .name   = "s3c2410-wdt",
>>> @@ -540,4 +668,3 @@ MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>, "
>>>   MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
>>>   MODULE_LICENSE("GPL");
>>>   MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
>>> -MODULE_ALIAS("platform:s3c2410-wdt");
>>> --
>>> 1.7.10.4
>>>
>>>
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