[PATCH v5 2/4] regulator: core: Parse regulator-off-on-delay-us generically

[Jishnu Prakash]

off_on_delay is normally fixed per regulator type in regulator_desc,
e.g. hardcoded for every LDO a driver supports. But the delay a rail
needs before it's safe to re-enable can depend on board-specific
factors like attached bulk capacitance, not just the regulator type,
so some individual regulators need a different value than their
type's default.

Add an off_on_delay field to struct regulation_constraints, parse
'regulator-off-on-delay-us' into it in of_get_regulation_constraints(),
and add a _regulator_get_off_on_delay() helper, so a
devicetree/board-constraint value takes precedence over the driver's
static regulator_desc value. This lets drivers rely on the core to
set this delay rather than parsing it themselves.

Suggested-by: Saikiran <bjsaikiran@xxxxxxxxx>
Signed-off-by: Jishnu Prakash <jishnu.prakash@xxxxxxxxxxxxxxxx>
---
 drivers/regulator/core.c          | 18 ++++++++++++++----
 drivers/regulator/of_regulator.c  |  4 ++++
 include/linux/regulator/machine.h |  4 ++++
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 6a4008f387b5..537384c55d6f 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1401,6 +1401,7 @@ static int machine_constraints_current(struct regulator_dev *rdev,
 }
 
 static int _regulator_do_enable(struct regulator_dev *rdev);
+static unsigned int _regulator_get_off_on_delay(struct regulator_dev *rdev);
 
 static int notif_set_limit(struct regulator_dev *rdev,
 			   int (*set)(struct regulator_dev *, int, int, bool),
@@ -1695,7 +1696,7 @@ static int set_machine_constraints(struct regulator_dev *rdev,
 
 		if (rdev->constraints->always_on)
 			rdev->use_count++;
-	} else if (rdev->desc->off_on_delay) {
+	} else if (_regulator_get_off_on_delay(rdev)) {
 		rdev->last_off = ktime_get();
 	}
 
@@ -2071,6 +2072,13 @@ static int _regulator_get_enable_time(struct regulator_dev *rdev)
 	return rdev->desc->enable_time;
 }
 
+static unsigned int _regulator_get_off_on_delay(struct regulator_dev *rdev)
+{
+	if (rdev->constraints && rdev->constraints->off_on_delay)
+		return rdev->constraints->off_on_delay;
+	return rdev->desc->off_on_delay;
+}
+
 static struct regulator_supply_alias *regulator_find_supply_alias(
 		struct device *dev, const char *supply)
 {
@@ -2985,6 +2993,7 @@ static inline int _regulator_check_status_enabled(struct regulator_dev *rdev)
 static int _regulator_do_enable(struct regulator_dev *rdev)
 {
 	int ret, delay;
+	unsigned int off_on_delay;
 
 	/* Query before enabling in case configuration dependent.  */
 	ret = _regulator_get_enable_time(rdev);
@@ -2997,11 +3006,12 @@ static int _regulator_do_enable(struct regulator_dev *rdev)
 
 	trace_regulator_enable(rdev_get_name(rdev));
 
-	if (rdev->desc->off_on_delay) {
+	off_on_delay = _regulator_get_off_on_delay(rdev);
+	if (off_on_delay) {
 		/* if needed, keep a distance of off_on_delay from last time
 		 * this regulator was disabled.
 		 */
-		ktime_t end = ktime_add_us(rdev->last_off, rdev->desc->off_on_delay);
+		ktime_t end = ktime_add_us(rdev->last_off, off_on_delay);
 		s64 remaining = ktime_us_delta(end, ktime_get_boottime());
 
 		if (remaining > 0)
@@ -3243,7 +3253,7 @@ static int _regulator_do_disable(struct regulator_dev *rdev)
 			return ret;
 	}
 
-	if (rdev->desc->off_on_delay)
+	if (_regulator_get_off_on_delay(rdev))
 		rdev->last_off = ktime_get_boottime();
 
 	trace_regulator_disable_complete(rdev_get_name(rdev));
diff --git a/drivers/regulator/of_regulator.c b/drivers/regulator/of_regulator.c
index 09e26febfc83..990946b27a7a 100644
--- a/drivers/regulator/of_regulator.c
+++ b/drivers/regulator/of_regulator.c
@@ -178,6 +178,10 @@ static int of_get_regulation_constraints(struct device *dev,
 	if (!ret)
 		constraints->enable_time = pval;
 
+	ret = of_property_read_u32(np, "regulator-off-on-delay-us", &pval);
+	if (!ret)
+		constraints->off_on_delay = pval;
+
 	ret = of_property_read_u32(np, "regulator-uv-less-critical-window-ms", &pval);
 	if (!ret)
 		constraints->uv_less_critical_window_ms = pval;
diff --git a/include/linux/regulator/machine.h b/include/linux/regulator/machine.h
index 1fc440c5c4c7..79b2d7cab934 100644
--- a/include/linux/regulator/machine.h
+++ b/include/linux/regulator/machine.h
@@ -163,6 +163,9 @@ struct notification_limit {
  *		      regulator_active_discharge values are used for
  *		      initialisation.
  * @enable_time: Turn-on time of the rails (unit: microseconds)
+ * @off_on_delay: Guard time (in uS), before re-enabling a regulator.  Takes
+ *		  precedence over the regulator_desc field of the same name
+ *		  when non-zero.
  * @uv_less_critical_window_ms: Specifies the time window (in milliseconds)
  *                              following a critical under-voltage (UV) event
  *                              during which less critical actions can be
@@ -222,6 +225,7 @@ struct regulation_constraints {
 	unsigned int settling_time_up;
 	unsigned int settling_time_down;
 	unsigned int enable_time;
+	unsigned int off_on_delay;
 	unsigned int uv_less_critical_window_ms;
 
 	unsigned int active_discharge;

-- 
2.43.0