[PATCH/RFC v4 1/4] regulator: core: add prepare and resume_early

[Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>]

The regulator-fixed driver is possible to be off by firmware
like PSCI while the system is suspended. If a consumer could get
such a condition from regulator_is_enabled(), it's useful by
consumers.

The regulator subsystem already has regulator-state-(standby|mem|disk)
sub-nodes and regulator-off-in-suspend property. However,
suitable regulator_ops APIs didn't exist.

So, add new regulator_ops APIs and prepare()/resume_early() in
the regulator_pm_ops to set/clear the condition by new APIs before
suspend() functions of consumers are called.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
---
 drivers/regulator/core.c         | 42 ++++++++++++++++++++++++++++++++++++++++
 include/linux/regulator/driver.h |  6 ++++++
 2 files changed, 48 insertions(+)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 03154f5..93eb2a3 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -5286,6 +5286,46 @@ void regulator_unregister(struct regulator_dev *rdev)
 EXPORT_SYMBOL_GPL(regulator_unregister);
 
 #ifdef CONFIG_SUSPEND
+static int regulator_prepare(struct device *dev)
+{
+	struct regulator_dev *rdev = dev_to_rdev(dev);
+	suspend_state_t state = pm_suspend_target_state;
+	struct regulator_state *rstate;
+	int ret = 0;
+
+	rstate = regulator_get_suspend_state(rdev, state);
+	if (rstate == NULL)
+		return 0;
+
+	regulator_lock(rdev);
+	if (rstate->enabled == DISABLE_IN_SUSPEND &&
+	    rdev->desc->ops->set_prepare_disable)
+		ret = rdev->desc->ops->set_prepare_disable(rdev);
+	regulator_unlock(rdev);
+
+	return ret;
+}
+
+static int regulator_resume_early(struct device *dev)
+{
+	struct regulator_dev *rdev = dev_to_rdev(dev);
+	suspend_state_t state = pm_suspend_target_state;
+	struct regulator_state *rstate;
+	int ret = 0;
+
+	rstate = regulator_get_suspend_state(rdev, state);
+	if (rstate == NULL)
+		return 0;
+
+	regulator_lock(rdev);
+	if (rstate->enabled == DISABLE_IN_SUSPEND &&
+	    rdev->desc->ops->clear_resume_early_disable)
+		ret = rdev->desc->ops->clear_resume_early_disable(rdev);
+	regulator_unlock(rdev);
+
+	return ret;
+}
+
 /**
  * regulator_suspend - prepare regulators for system wide suspend
  * @dev: ``&struct device`` pointer that is passed to _regulator_suspend()
@@ -5336,6 +5376,8 @@ static int regulator_resume(struct device *dev)
 
 #ifdef CONFIG_PM
 static const struct dev_pm_ops __maybe_unused regulator_pm_ops = {
+	.prepare	= regulator_prepare,
+	.resume_early	= regulator_resume_early,
 	.suspend	= regulator_suspend,
 	.resume		= regulator_resume,
 };
diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h
index 7eb9fea..299a504 100644
--- a/include/linux/regulator/driver.h
+++ b/include/linux/regulator/driver.h
@@ -115,6 +115,10 @@ enum regulator_status {
  *                      suspended.
  * @set_suspend_disable: Mark the regulator as disabled when the system is
  *                       suspended.
+ * @set_prepare_disable: Mark the regulator as disabled when the system is
+ *                       suspending.
+ * @clear_resume_early_disable: Unmark the regulator as disabled when
+ *                              the system is resuming.
  * @set_suspend_mode: Set the operating mode for the regulator when the
  *                    system is suspended.
  *
@@ -195,6 +199,8 @@ struct regulator_ops {
 	/* enable/disable regulator in suspend state */
 	int (*set_suspend_enable) (struct regulator_dev *);
 	int (*set_suspend_disable) (struct regulator_dev *);
+	int (*set_prepare_disable) (struct regulator_dev *);
+	int (*clear_resume_early_disable) (struct regulator_dev *);
 
 	/* set regulator suspend operating mode (defined in consumer.h) */
 	int (*set_suspend_mode) (struct regulator_dev *, unsigned int mode);
-- 
2.7.4