Devm helpers for regulator get and enable

Merge series from Matti Vaittinen <mazziesaccount@gmail.com>:

A few* drivers seem to use pattern demonstrated by pseudocode:

- devm_regulator_get()
- regulator_enable()
- devm_add_action_or_reset(regulator_disable())

Introducing devm helpers for this pattern would remove bunch of code from
drivers. Typically following:

- replace 3 calls (devm_regulator_get[_optional](), regulator_enable(),
  devm_add_action_or_reset()) with just one
  (devm_regulator_get_enable[_optional]()).
- drop disable callback.
- remove stored pointer to struct regulator - which can lead to problem
  when an devm action for regulator_disable is used.

I believe this simplifies things by removing some dublicated code.

The suggested managed 'get_enable' APIs do not return the pointer to
regulators for user because any call to regulator_disable()
(or regulator_enable()) may easily lead to regulator enable count imbalance
upon device detach. (Eg, if someone calls regulator_disable() and the
device is then detached before user has re-enabled the regulator). Not
returning the pointer to obtained regulator to caller is a good hint that
the enable/disable should not be manually handled when these APIs are used.

OTOH, not returning the pointer reduces the use-cases by not allowing
the consumers to perform other regulator actions. For example request the
voltages. A few drivers which used the "get, enable,
devm_action_to_disable" did also query the voltages. The API does not suit
needs of such users.

1 files changed, 164 insertions, 0 deletions

diff --git a/drivers/regulator/devres.c b/drivers/regulator/devres.c
index 32823a87fd40..3265e75e97ab 100644
--- a/drivers/regulator/devres.c
+++ b/drivers/regulator/devres.c
@@ -70,6 +70,65 @@ struct regulator *devm_regulator_get_exclusive(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(devm_regulator_get_exclusive);
 
+static void regulator_action_disable(void *d)
+{
+	struct regulator *r = (struct regulator *)d;
+
+	regulator_disable(r);
+}
+
+static int _devm_regulator_get_enable(struct device *dev, const char *id,
+				      int get_type)
+{
+	struct regulator *r;
+	int ret;
+
+	r = _devm_regulator_get(dev, id, get_type);
+	if (IS_ERR(r))
+		return PTR_ERR(r);
+
+	ret = regulator_enable(r);
+	if (!ret)
+		ret = devm_add_action_or_reset(dev, &regulator_action_disable, r);
+
+	if (ret)
+		devm_regulator_put(r);
+
+	return ret;
+}
+
+/**
+ * devm_regulator_get_enable_optional - Resource managed regulator get and enable
+ * @dev: device to supply
+ * @id:  supply name or regulator ID.
+ *
+ * Get and enable regulator for duration of the device life-time.
+ * regulator_disable() and regulator_put() are automatically called on driver
+ * detach. See regulator_get_optional() and regulator_enable() for more
+ * information.
+ */
+int devm_regulator_get_enable_optional(struct device *dev, const char *id)
+{
+	return _devm_regulator_get_enable(dev, id, OPTIONAL_GET);
+}
+EXPORT_SYMBOL_GPL(devm_regulator_get_enable_optional);
+
+/**
+ * devm_regulator_get_enable - Resource managed regulator get and enable
+ * @dev: device to supply
+ * @id:  supply name or regulator ID.
+ *
+ * Get and enable regulator for duration of the device life-time.
+ * regulator_disable() and regulator_put() are automatically called on driver
+ * detach. See regulator_get() and regulator_enable() for more
+ * information.
+ */
+int devm_regulator_get_enable(struct device *dev, const char *id)
+{
+	return _devm_regulator_get_enable(dev, id, NORMAL_GET);
+}
+EXPORT_SYMBOL_GPL(devm_regulator_get_enable);
+
 /**
  * devm_regulator_get_optional - Resource managed regulator_get_optional()
  * @dev: device to supply
@@ -194,6 +253,111 @@ int devm_regulator_bulk_get_const(struct device *dev, int num_consumers,
 }
 EXPORT_SYMBOL_GPL(devm_regulator_bulk_get_const);
 
+static int devm_regulator_bulk_match(struct device *dev, void *res,
+				     void *data)
+{
+	struct regulator_bulk_devres *match = res;
+	struct regulator_bulk_data *target = data;
+
+	/*
+	 * We check the put uses same consumer list as the get did.
+	 * We _could_ scan all entries in consumer array and check the
+	 * regulators match but ATM I don't see the need. We can change this
+	 * later if needed.
+	 */
+	return match->consumers == target;
+}
+
+/**
+ * devm_regulator_bulk_put - Resource managed regulator_bulk_put()
+ * @consumers: consumers to free
+ *
+ * Deallocate regulators allocated with devm_regulator_bulk_get(). Normally
+ * this function will not need to be called and the resource management
+ * code will ensure that the resource is freed.
+ */
+void devm_regulator_bulk_put(struct regulator_bulk_data *consumers)
+{
+	int rc;
+	struct regulator *regulator = consumers[0].consumer;
+
+	rc = devres_release(regulator->dev, devm_regulator_bulk_release,
+			    devm_regulator_bulk_match, consumers);
+	if (rc != 0)
+		WARN_ON(rc);
+}
+EXPORT_SYMBOL_GPL(devm_regulator_bulk_put);
+
+static void devm_regulator_bulk_disable(void *res)
+{
+	struct regulator_bulk_devres *devres = res;
+	int i;
+
+	for (i = 0; i < devres->num_consumers; i++)
+		regulator_disable(devres->consumers[i].consumer);
+}
+
+/**
+ * devm_regulator_bulk_get_enable - managed get'n enable multiple regulators
+ *
+ * @dev:           device to supply
+ * @num_consumers: number of consumers to register
+ * @id:            list of supply names or regulator IDs
+ *
+ * @return 0 on success, an errno on failure.
+ *
+ * This helper function allows drivers to get several regulator
+ * consumers in one operation with management, the regulators will
+ * automatically be freed when the device is unbound.  If any of the
+ * regulators cannot be acquired then any regulators that were
+ * allocated will be freed before returning to the caller.
+ */
+int devm_regulator_bulk_get_enable(struct device *dev, int num_consumers,
+				   const char * const *id)
+{
+	struct regulator_bulk_devres *devres;
+	struct regulator_bulk_data *consumers;
+	int i, ret;
+
+	devres = devm_kmalloc(dev, sizeof(*devres), GFP_KERNEL);
+	if (!devres)
+		return -ENOMEM;
+
+	devres->consumers = devm_kcalloc(dev, num_consumers, sizeof(*consumers),
+					 GFP_KERNEL);
+	consumers = devres->consumers;
+	if (!consumers)
+		return -ENOMEM;
+
+	devres->num_consumers = num_consumers;
+
+	for (i = 0; i < num_consumers; i++)
+		consumers[i].supply = id[i];
+
+	ret = devm_regulator_bulk_get(dev, num_consumers, consumers);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < num_consumers; i++) {
+		ret = regulator_enable(consumers[i].consumer);
+		if (ret)
+			goto unwind;
+	}
+
+	ret = devm_add_action(dev, devm_regulator_bulk_disable, devres);
+	if (!ret)
+		return 0;
+
+unwind:
+	while (--i >= 0)
+		regulator_disable(consumers[i].consumer);
+
+	devm_regulator_bulk_put(consumers);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(devm_regulator_bulk_get_enable);
+
 static void devm_rdev_release(struct device *dev, void *res)
 {
 	regulator_unregister(*(struct regulator_dev **)res);