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

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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@xxxxxxxxxxxx> 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@xxxxxxxxxxx>
---
  .../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@xxxxxxxxxxxx>, "
  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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