regulator: enable/disable refcounting

Make the <linux/regulator.h> framework treat enable/disable call
pairs like the <linux/clk.h> and <linux/interrupt.h> frameworks do:
they're refcounted, so that different parts of a driver don't need
to put work into coordination that frameworks normally handle.
It's a minor object code shrink.

It also makes the regulator_is_disabled() kerneldoc say what it's
actually returning:  return value is not a refcount, and may report
an error (e.g. I/O error from I2C).

It also fixes some minor regulator_put() goofage:  removing unlocked
access to the enable state.  (But still not making regulator put/get
match the refcounting pattern they invoke.)

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 9a644d41b8136e7b3f133d0e91986a99e8c2ae22..c2b7ec901036434c90689335cdba18062dbddbb4 100644 (file)
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -79,7 +79,7 @@ struct regulator {
        int uA_load;
        int min_uV;
        int max_uV;
-       int enabled; /* client has called enabled */
+       int enabled; /* count of client enables */
        char *supply_name;
        struct device_attribute dev_attr;
        struct regulator_dev *rdev;
@@ -963,16 +963,13 @@ void regulator_put(struct regulator *regulator)
        if (regulator == NULL || IS_ERR(regulator))
                return;
 
-       if (regulator->enabled) {
-               printk(KERN_WARNING "Releasing supply %s while enabled\n",
-                      regulator->supply_name);
-               WARN_ON(regulator->enabled);
-               regulator_disable(regulator);
-       }
-
        mutex_lock(&regulator_list_mutex);
        rdev = regulator->rdev;
 
+       if (WARN(regulator->enabled, "Releasing supply %s while enabled\n",
+                              regulator->supply_name))
+               _regulator_disable(rdev);
+
        /* remove any sysfs entries */
        if (regulator->dev) {
                sysfs_remove_link(&rdev->dev.kobj, regulator->supply_name);
@@ -1042,21 +1039,17 @@ static int _regulator_enable(struct regulator_dev *rdev)
  */
 int regulator_enable(struct regulator *regulator)
 {
-       int ret;
-
-       if (regulator->enabled) {
-               printk(KERN_CRIT "Regulator %s already enabled\n",
-                      regulator->supply_name);
-               WARN_ON(regulator->enabled);
-               return 0;
-       }
+       struct regulator_dev *rdev = regulator->rdev;
+       int ret = 0;
 
-       mutex_lock(&regulator->rdev->mutex);
-       regulator->enabled = 1;
-       ret = _regulator_enable(regulator->rdev);
-       if (ret != 0)
-               regulator->enabled = 0;
-       mutex_unlock(&regulator->rdev->mutex);
+       mutex_lock(&rdev->mutex);
+       if (regulator->enabled == 0)
+               ret = _regulator_enable(rdev);
+       else if (regulator->enabled < 0)
+               ret = -EIO;
+       if (ret == 0)
+               regulator->enabled++;
+       mutex_unlock(&rdev->mutex);
        return ret;
 }
 EXPORT_SYMBOL_GPL(regulator_enable);
@@ -1108,19 +1101,21 @@ static int _regulator_disable(struct regulator_dev *rdev)
  */
 int regulator_disable(struct regulator *regulator)
 {
-       int ret;
-
-       if (!regulator->enabled) {
-               printk(KERN_ERR "%s: not in use by this consumer\n",
-                       __func__);
-               return 0;
-       }
+       struct regulator_dev *rdev = regulator->rdev;
+       int ret = 0;
 
-       mutex_lock(&regulator->rdev->mutex);
-       regulator->enabled = 0;
-       regulator->uA_load = 0;
-       ret = _regulator_disable(regulator->rdev);
-       mutex_unlock(&regulator->rdev->mutex);
+       mutex_lock(&rdev->mutex);
+       if (regulator->enabled == 1) {
+               ret = _regulator_disable(rdev);
+               if (ret == 0)
+                       regulator->uA_load = 0;
+       } else if (WARN(regulator->enabled <= 0,
+                       "unbalanced disables for supply %s\n",
+                       regulator->supply_name))
+               ret = -EIO;
+       if (ret == 0)
+               regulator->enabled--;
+       mutex_unlock(&rdev->mutex);
        return ret;
 }
 EXPORT_SYMBOL_GPL(regulator_disable);
@@ -1196,7 +1191,13 @@ out:
  * regulator_is_enabled - is the regulator output enabled
  * @regulator: regulator source
  *
- * Returns zero for disabled otherwise return number of enable requests.
+ * Returns positive if the regulator driver backing the source/client
+ * has requested that the device be enabled, zero if it hasn't, else a
+ * negative errno code.
+ *
+ * Note that the device backing this regulator handle can have multiple
+ * users, so it might be enabled even if regulator_enable() was never
+ * called for this particular source.
  */
 int regulator_is_enabled(struct regulator *regulator)
 {