Re: [PATCH V4 2/4] watchdog: stm32: add pclk feature for stm32mp1

Guenter Roeck <linux@xxxxxxxxxxxx> · Fri, 22 Jun 2018 06:40:31 -0700

On 06/22/2018 02:15 AM, Ludovic BARRE wrote:


On 06/21/2018 06:53 PM, Guenter Roeck wrote:
On Thu, Jun 21, 2018 at 11:02:15AM +0200, Ludovic Barre wrote:
From: Ludovic Barre <ludovic.barre@xxxxxx>

This patch adds compatible data to manage pclk clock by
compatible. Adds stm32mp1 support which requires pclk clock.

Signed-off-by: Ludovic Barre <ludovic.barre@xxxxxx>
---
  drivers/watchdog/stm32_iwdg.c | 116 +++++++++++++++++++++++++++---------------
  1 file changed, 74 insertions(+), 42 deletions(-)

diff --git a/drivers/watchdog/stm32_iwdg.c b/drivers/watchdog/stm32_iwdg.c
index c97ad56..e00e3b3 100644
--- a/drivers/watchdog/stm32_iwdg.c
+++ b/drivers/watchdog/stm32_iwdg.c
@@ -11,12 +11,13 @@
  #include <linux/clk.h>
  #include <linux/delay.h>
-#include <linux/kernel.h>
-#include <linux/module.h>
  #include <linux/interrupt.h>
  #include <linux/io.h>
  #include <linux/iopoll.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
  #include <linux/of.h>
+#include <linux/of_device.h>
  #include <linux/platform_device.h>
  #include <linux/watchdog.h>
@@ -54,11 +55,15 @@
  #define TIMEOUT_US    100000
  #define SLEEP_US    1000
+#define HAS_PCLK    true
+
  struct stm32_iwdg {
      struct watchdog_device    wdd;
      void __iomem        *regs;
-    struct clk        *clk;
+    struct clk        *clk_lsi;
+    struct clk        *clk_pclk;
      unsigned int        rate;
+    bool            has_pclk;
  };
  static inline u32 reg_read(void __iomem *base, u32 reg)
@@ -133,6 +138,44 @@ static int stm32_iwdg_set_timeout(struct watchdog_device *wdd,
      return 0;
  }
+static int stm32_iwdg_clk_init(struct platform_device *pdev,
+                   struct stm32_iwdg *wdt)
+{
+    u32 ret;
+
+    wdt->clk_lsi = devm_clk_get(&pdev->dev, "lsi");

I just noticed a subtle difference: This used to be
            devm_clk_get(&pdev->dev, NULL);
which would always get the first clock, no matter how it is named.
Can that cause problems with backward compatibility ?

You are right Guenter.

When there are multiple clocks, I prefer to use name interface.
I find it easier to use, and avoid misunderstanding.

Today, only one "dtsi" define the watchdog and it's disabled
(stm32f429.dtsi). I think it's good moment to move to clock named
(before it is used anymore).

But you are right I forgot to change stm32f429.dtsi.
If I add a commit for stm32f429.dtsi, it's Ok for you ?


Not really. You are imposing a personal preference on others,
and you would make stm32f429.dtsi inconsistent since it doesn't
use clock names for anything else. This in turn means that people
will have an endless source of irritation since they will need
a clock name for this node but not for others.

You will have to get the arm and DT maintainers to agree on this change.

Thanks,
Guenter

BR
Ludo


Thanks,
Guenter

+    if (IS_ERR(wdt->clk_lsi)) {
+        dev_err(&pdev->dev, "Unable to get lsi clock\n");
+        return PTR_ERR(wdt->clk_lsi);
+    }
+
+    /* optional peripheral clock */
+    if (wdt->has_pclk) {
+        wdt->clk_pclk = devm_clk_get(&pdev->dev, "pclk");
+        if (IS_ERR(wdt->clk_pclk)) {
+            dev_err(&pdev->dev, "Unable to get pclk clock\n");
+            return PTR_ERR(wdt->clk_pclk);
+        }
+
+        ret = clk_prepare_enable(wdt->clk_pclk);
+        if (ret) {
+            dev_err(&pdev->dev, "Unable to prepare pclk clock\n");
+            return ret;
+        }
+    }
+
+    ret = clk_prepare_enable(wdt->clk_lsi);
+    if (ret) {
+        dev_err(&pdev->dev, "Unable to prepare lsi clock\n");
+        clk_disable_unprepare(wdt->clk_pclk);
+        return ret;
+    }
+
+    wdt->rate = clk_get_rate(wdt->clk_lsi);
+
+    return 0;
+}
+
  static const struct watchdog_info stm32_iwdg_info = {
      .options    = WDIOF_SETTIMEOUT |
                WDIOF_MAGICCLOSE |
@@ -147,49 +190,42 @@ static const struct watchdog_ops stm32_iwdg_ops = {
      .set_timeout    = stm32_iwdg_set_timeout,
  };
+static const struct of_device_id stm32_iwdg_of_match[] = {
+    { .compatible = "st,stm32-iwdg", .data = (void *)!HAS_PCLK },
+    { .compatible = "st,stm32mp1-iwdg", .data = (void *)HAS_PCLK },
+    { /* end node */ }
+};
+MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match);
+
  static int stm32_iwdg_probe(struct platform_device *pdev)
  {
      struct watchdog_device *wdd;
+    const struct of_device_id *match;
      struct stm32_iwdg *wdt;
      struct resource *res;
-    void __iomem *regs;
-    struct clk *clk;
      int ret;
+    match = of_match_device(stm32_iwdg_of_match, &pdev->dev);
+    if (!match)
+        return -ENODEV;
+
+    wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
+    if (!wdt)
+        return -ENOMEM;
+
+    wdt->has_pclk = match->data;
+
      /* This is the timer base. */
      res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-    regs = devm_ioremap_resource(&pdev->dev, res);
-    if (IS_ERR(regs)) {
+    wdt->regs = devm_ioremap_resource(&pdev->dev, res);
+    if (IS_ERR(wdt->regs)) {
          dev_err(&pdev->dev, "Could not get resource\n");
-        return PTR_ERR(regs);
+        return PTR_ERR(wdt->regs);
      }
-    clk = devm_clk_get(&pdev->dev, NULL);
-    if (IS_ERR(clk)) {
-        dev_err(&pdev->dev, "Unable to get clock\n");
-        return PTR_ERR(clk);
-    }
-
-    ret = clk_prepare_enable(clk);
-    if (ret) {
-        dev_err(&pdev->dev, "Unable to prepare clock %p\n", clk);
+    ret = stm32_iwdg_clk_init(pdev, wdt);
+    if (ret)
          return ret;
-    }
-
-    /*
-     * Allocate our watchdog driver data, which has the
-     * struct watchdog_device nested within it.
-     */
-    wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
-    if (!wdt) {
-        ret = -ENOMEM;
-        goto err;
-    }
-
-    /* Initialize struct stm32_iwdg. */
-    wdt->regs = regs;
-    wdt->clk = clk;
-    wdt->rate = clk_get_rate(clk);
      /* Initialize struct watchdog_device. */
      wdd = &wdt->wdd;
@@ -217,7 +253,8 @@ static int stm32_iwdg_probe(struct platform_device *pdev)
      return 0;
  err:
-    clk_disable_unprepare(clk);
+    clk_disable_unprepare(wdt->clk_lsi);
+    clk_disable_unprepare(wdt->clk_pclk);
      return ret;
  }
@@ -227,23 +264,18 @@ static int stm32_iwdg_remove(struct platform_device *pdev)
      struct stm32_iwdg *wdt = platform_get_drvdata(pdev);
      watchdog_unregister_device(&wdt->wdd);
-    clk_disable_unprepare(wdt->clk);
+    clk_disable_unprepare(wdt->clk_lsi);
+    clk_disable_unprepare(wdt->clk_pclk);
      return 0;
  }
-static const struct of_device_id stm32_iwdg_of_match[] = {
-    { .compatible = "st,stm32-iwdg" },
-    { /* end node */ }
-};
-MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match);
-
  static struct platform_driver stm32_iwdg_driver = {
      .probe        = stm32_iwdg_probe,
      .remove        = stm32_iwdg_remove,
      .driver = {
          .name    = "iwdg",
-        .of_match_table = stm32_iwdg_of_match,
+        .of_match_table = of_match_ptr(stm32_iwdg_of_match),
      },
  };
  module_platform_driver(stm32_iwdg_driver);
--
2.7.4

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