Re: [PATCH v2 1/3] clk: add devm_clk_prepare_enable() helper

[Guenter Roeck]

On 3/4/21 2:12 PM, Rasmus Villemoes wrote:
> Add a managed wrapper for clk_prepare_enable().
> 
> Signed-off-by: Rasmus Villemoes 

That has been tried several times, including by yours truly,
and has always been rejected.

Just use devm_add_action_or_reset() like many other watchdog
drivers.

Guenter

[PATCH v2 1/3] clk: add devm_clk_prepare_enable() helper

[Rasmus Villemoes]

Add a managed wrapper for clk_prepare_enable().

Signed-off-by: Rasmus Villemoes 
---
 .../driver-api/driver-model/devres.rst|  1 +
 drivers/clk/clk-devres.c  | 29 +++
 include/linux/clk.h   | 13 +
 3 files changed, 43 insertions(+)

diff --git a/Documentation/driver-api/driver-model/devres.rst 
b/Documentation/driver-api/driver-model/devres.rst
index cd8b6e657b94..8ee2557f9ad7 100644
--- a/Documentation/driver-api/driver-model/devres.rst
+++ b/Documentation/driver-api/driver-model/devres.rst
@@ -253,6 +253,7 @@ CLOCK
   devm_clk_hw_register()
   devm_of_clk_add_hw_provider()
   devm_clk_hw_register_clkdev()
+  devm_clk_prepare_enable()
 
 DMA
   dmaenginem_async_device_register()
diff --git a/drivers/clk/clk-devres.c b/drivers/clk/clk-devres.c
index be160764911b..d5bfa8cd7347 100644
--- a/drivers/clk/clk-devres.c
+++ b/drivers/clk/clk-devres.c
@@ -156,3 +156,32 @@ struct clk *devm_get_clk_from_child(struct device *dev,
return clk;
 }
 EXPORT_SYMBOL(devm_get_clk_from_child);
+
+static void devm_clk_disable_unprepare(struct device *dev, void *res)
+{
+   clk_disable_unprepare(*(struct clk **)res);
+}
+
+int devm_clk_prepare_enable(struct device *dev, struct clk *clk)
+{
+   struct clk **ptr;
+   int ret;
+
+   if (!clk)
+   return 0;
+
+   ptr = devres_alloc(devm_clk_disable_unprepare, sizeof(*ptr), 
GFP_KERNEL);
+   if (!ptr)
+   return -ENOMEM;
+
+   ret = clk_prepare_enable(clk);
+   if (!ret) {
+   *ptr = clk;
+   devres_add(dev, ptr);
+   } else {
+   devres_free(ptr);
+   }
+
+   return ret;
+}
+EXPORT_SYMBOL(devm_clk_prepare_enable);
diff --git a/include/linux/clk.h b/include/linux/clk.h
index 266e8de3cb51..04d135520480 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -485,6 +485,19 @@ struct clk *devm_clk_get_optional(struct device *dev, 
const char *id);
  */
 struct clk *devm_get_clk_from_child(struct device *dev,
struct device_node *np, const char *con_id);
+/**
+ * devm_clk_prepare_enable - prepare and enable a clock source
+ * @dev: device for clock "consumer"
+ * @clk: clock source
+ *
+ * This function calls clk_prepare_enable() on @clk, and ensures the
+ * clock will automatically be disabled and unprepared when the device
+ * is unbound from the bus.
+ *
+ * Must not be called from within atomic context.
+ */
+int devm_clk_prepare_enable(struct device *dev, struct clk *clk);
+
 /**
  * clk_rate_exclusive_get - get exclusivity over the rate control of a
  *  producer
-- 
2.29.2