[PATCH v2] Regulator: add suspend-finish API for regulator core.

[MyungJoo Ham]

The regulator core had suspend-prepare that turns off the regulators
when entering a system-wide suspend. However, it did not have
suspend-finish that pairs with suspend-prepare and the regulator core
has assumed that the regulator devices and their drivers support
autonomous recover at resume.

This patch adds regulator_suspend_finish that pairs with the
previously-existed regulator_suspend_prepare. The function
regulator_suspend_finish turns on the regulators that have always_on set
or positive use_count so that we can reset the regulator states
appropriately at resume.

In regulator_suspend_finish, if has_full_constraints, it disables
unnecessary regulators.

Signed-off-by: MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
---
 drivers/regulator/core.c          |   40 +++++++++++++++++++++++++++++++++++++
 include/linux/regulator/machine.h |    1 +
 2 files changed, 41 insertions(+), 0 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 9fa2095..4d34cc0 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -2653,6 +2653,46 @@ out:
 EXPORT_SYMBOL_GPL(regulator_suspend_prepare);
 
 /**
+ * regulator_suspend_prepare - resume regulators from system wide suspend
+ *
+ * Turn on regulators that might be turned off by regulator_suspend_prepare.
+ */
+int regulator_suspend_finish(void)
+{
+	struct regulator_dev *rdev;
+	int ret = 0, error;
+
+	mutex_lock(&regulator_list_mutex);
+	list_for_each_entry(rdev, &regulator_list, list) {
+		struct regulator_ops *ops = rdev->desc->ops;
+
+		mutex_lock(&rdev->mutex);
+		if ((rdev->use_count > 0  || rdev->constraints->always_on) &&
+				ops->enable) {
+			error = ops->enable(rdev);
+			if (error)
+				ret = error;
+		} else {
+			if (!has_full_constraints)
+				goto unlock;
+			if (!ops->disable)
+				goto unlock;
+			if (ops->is_enabled && !ops->is_enabled(rdev))
+				goto unlock;
+
+			error = ops->disable(rdev);
+			if (error)
+				ret = error;
+		}
+unlock:
+		mutex_unlock(&rdev->mutex);
+	}
+	mutex_unlock(&regulator_list_mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(regulator_suspend_finish);
+
+/**
  * regulator_has_full_constraints - the system has fully specified constraints
  *
  * Calling this function will cause the regulator API to disable all
diff --git a/include/linux/regulator/machine.h b/include/linux/regulator/machine.h
index 761c745..c4c4fc4 100644
--- a/include/linux/regulator/machine.h
+++ b/include/linux/regulator/machine.h
@@ -186,6 +186,7 @@ struct regulator_init_data {
 };
 
 int regulator_suspend_prepare(suspend_state_t state);
+int regulator_suspend_finish(void);
 
 #ifdef CONFIG_REGULATOR
 void regulator_has_full_constraints(void);
-- 
1.7.1

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