[PATCH v2] pwm: add devm_pwm_get() and devm_pwm_put()

[PATCH v2] pwm: add devm_pwm_get() and devm_pwm_put()

[Alexandre Courbot]

Add resource managed variants of pwm_get() and pwm_put() for
convenience. Code is largely inspired by the equivalent devm functions
of the regulator framework.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
 Documentation/driver-model/devres.txt |  4 +++
 Documentation/pwm.txt                 |  3 +-
 drivers/pwm/core.c                    | 68 +++++++++++++++++++++++++++++++++++
 include/linux/pwm.h                   |  3 ++
 4 files changed, 77 insertions(+), 1 deletion(-)

diff --git a/Documentation/driver-model/devres.txt b/Documentation/driver-model/devres.txt
index 950856b..43cff70 100644
--- a/Documentation/driver-model/devres.txt
+++ b/Documentation/driver-model/devres.txt
@@ -284,3 +284,7 @@ CLOCK
 PINCTRL
   devm_pinctrl_get()
   devm_pinctrl_put()
+
+PWM
+  devm_pwm_get()
+  devm_pwm_put()
diff --git a/Documentation/pwm.txt b/Documentation/pwm.txt
index 554290e..47cd24d 100644
--- a/Documentation/pwm.txt
+++ b/Documentation/pwm.txt
@@ -36,7 +36,8 @@ Legacy users can request a PWM device using pwm_request() and free it
 after usage with pwm_free().
 
 New users should use the pwm_get() function and pass to it the consumer
-device or a consumer name. pwm_put() is used to free the PWM device.
+device or a consumer name. pwm_put() is used to free the PWM device. Devm
+variants of these functions also exist.
 
 After being requested a PWM has to be configured using:
 
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index ecb7690..62315d7 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -624,6 +624,74 @@ out:
 }
 EXPORT_SYMBOL_GPL(pwm_put);
 
+static void devm_pwm_release(struct device *dev, void *res)
+{
+	pwm_put(*(struct pwm_device **)res);
+}
+
+/**
+ * devm_pwm_get() - Resource managed pwm_get()
+ * @dev: device for PWM consumer
+ * @con_id: consumer name
+ *
+ * This function performs like pwm_get() but the acquired PWM device will
+ * automatically be released on driver detach.
+ *
+ * Lookup is first attempted using DT. If the device was not instantiated from
+ * a device tree, a PWM chip and a relative index is looked up via a table
+ * supplied by board setup code (see pwm_add_table()).
+ *
+ * Once a PWM chip has been found the specified PWM device will be requested
+ * and is ready to be used.
+ */
+struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id)
+{
+	struct pwm_device **ptr, *pwm;
+
+	ptr = devres_alloc(devm_pwm_release, sizeof(**ptr), GFP_KERNEL);
+	if (!ptr)
+		return ERR_PTR(-ENOMEM);
+
+	pwm = pwm_get(dev, con_id);
+	if (!IS_ERR(pwm)) {
+		*ptr = pwm;
+		devres_add(dev, ptr);
+	} else {
+		devres_free(ptr);
+	}
+
+	return pwm;
+}
+EXPORT_SYMBOL_GPL(devm_pwm_get);
+
+static int devm_pwm_match(struct device *dev, void *res, void *data)
+{
+	struct pwm_device **p = res;
+
+	if (WARN_ON(!p || !*p))
+		return 0;
+
+	return *p == data;
+}
+
+/**
+ * devm_pwm_put() - Resource managed pwm_put()
+ * @dev: device for PWM consumer
+ * @pwm: PWM device
+ *
+ * Release a PWM previously allocated using devm_pwm_get. Calling this function
+ * is usually not needed as devm-allocated resources are automatically released
+ * on driver detach.
+ */
+void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
+{
+	int ret;
+
+	ret = devres_release(dev, devm_pwm_release, devm_pwm_match, pwm);
+	WARN_ON(ret);
+}
+EXPORT_SYMBOL_GPL(devm_pwm_put);
+
 #ifdef CONFIG_DEBUG_FS
 static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
 {
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 21d076c..8ddc824 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -125,6 +125,9 @@ struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
 struct pwm_device *pwm_get(struct device *dev, const char *consumer);
 void pwm_put(struct pwm_device *pwm);
 
+struct pwm_device *devm_pwm_get(struct device *dev, const char *consumer);
+void devm_pwm_put(struct device *dev, struct pwm_device *pwm);
+
 struct pwm_lookup {
 	struct list_head list;
 	const char *provider;
-- 
1.7.11.3

Re: [PATCH v2] pwm: add devm_pwm_get() and devm_pwm_put()

[Thierry Reding]

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On Wed, Aug 01, 2012 at 07:20:58PM +0900, Alexandre Courbot wrote:
> Add resource managed variants of pwm_get() and pwm_put() for
> convenience. Code is largely inspired by the equivalent devm functions
> of the regulator framework.
> 
> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>

Applied, with minor editorial fixups. Thanks.

Thierry

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