[PATCH v3] regulator: Propagate voltage changes to supply regulators

[PATCH v3] regulator: Propagate voltage changes to supply regulators

[Sascha Hauer]

Until now changing the voltage of a regulator only ever effected the
regulator itself, but never its supplies. It's a common pattern though
to put LDO regulators behind switching regulators. The switching
regulators efficiently drop the input voltage but have a high ripple on
their output. The output is then cleaned up by the LDOs. For higher
energy efficiency the voltage drop at the LDOs should be minimized. This
series adds support for such a scenario. Another case voltage
propagation is useful is simple switches which are abstracted as
regulators. These can now offer voltage settings to their consumers
which are transparently passed to the switches supply.

Please review, any input welcome.

Changes since v2:
- Skip already applied patches
- create regulator_map_voltage() and use it in favour of
  regulator_get_voltage_floor()

Changes since RFC (v1):
- split into more patches
- Only do voltage propagation when we have a supply and either a minimum
  dropout voltage is specified or the regulator is a switch (lacks a
  get_voltage operation)

Sascha

[PATCH 1/3] regulator: core: Factor out regulator_map_voltage

[Sascha Hauer]

_regulator_call_set_voltage has code to translate a minimum/maximum
voltage pair into a selector. This code is useful for others aswell,
so create a regulator_map_voltage function.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 drivers/regulator/core.c | 35 ++++++++++++++++++-----------------
 1 file changed, 18 insertions(+), 17 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 5bd54a5..fd22380 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -2663,6 +2663,23 @@ int regulator_is_supported_voltage(struct regulator *regulator,
 }
 EXPORT_SYMBOL_GPL(regulator_is_supported_voltage);
 
+static int regulator_map_voltage(struct regulator_dev *rdev, int min_uV,
+				 int max_uV)
+{
+	const struct regulator_desc *desc = rdev->desc;
+
+	if (desc->ops->map_voltage)
+		return desc->ops->map_voltage(rdev, min_uV, max_uV);
+
+	if (desc->ops->list_voltage == regulator_list_voltage_linear)
+		return regulator_map_voltage_linear(rdev, min_uV, max_uV);
+
+	if (desc->ops->list_voltage == regulator_list_voltage_linear_range)
+		return regulator_map_voltage_linear_range(rdev, min_uV, max_uV);
+
+	return regulator_map_voltage_iterate(rdev, min_uV, max_uV);
+}
+
 static int _regulator_call_set_voltage(struct regulator_dev *rdev,
 				       int min_uV, int max_uV,
 				       unsigned *selector)
@@ -2751,23 +2768,7 @@ static int _regulator_do_set_voltage(struct regulator_dev *rdev,
 		}
 
 	} else if (rdev->desc->ops->set_voltage_sel) {
-		if (rdev->desc->ops->map_voltage) {
-			ret = rdev->desc->ops->map_voltage(rdev, min_uV,
-							   max_uV);
-		} else {
-			if (rdev->desc->ops->list_voltage ==
-			    regulator_list_voltage_linear)
-				ret = regulator_map_voltage_linear(rdev,
-								min_uV, max_uV);
-			else if (rdev->desc->ops->list_voltage ==
-				 regulator_list_voltage_linear_range)
-				ret = regulator_map_voltage_linear_range(rdev,
-								min_uV, max_uV);
-			else
-				ret = regulator_map_voltage_iterate(rdev,
-								min_uV, max_uV);
-		}
-
+		ret = regulator_map_voltage(rdev, min_uV, max_uV);
 		if (ret >= 0) {
 			best_val = rdev->desc->ops->list_voltage(rdev, ret);
 			if (min_uV <= best_val && max_uV >= best_val) {
-- 
2.6.1

[PATCH 2/3] regulator: core: Propagate voltage changes to supply regulators

[Sascha Hauer]

Until now changing the voltage of a regulator only ever effected the
regulator itself, but never its supplies. It's a common pattern though
to put LDO regulators behind switching regulators. The switching
regulators efficiently drop the input voltage but have a high ripple on
their output. The output is then cleaned up by the LDOs. For higher
energy efficiency the voltage drop at the LDOs should be minimized. For
this scenario we need to propagate the voltage change to the supply
regulators. Another scenario where voltage propagation is desired is
a regulator which only consists of a switch and thus cannot regulate
voltages itself. In this case we can pass setting voltages to the
supply.

This patch adds support for voltage propagation. We do voltage
propagation when the current regulator has a minimum dropout voltage
specified or if the current regulator lacks a get_voltage operation
(indicating it's a switch and not a regulator).

Changing the supply voltage must be done carefully. When we are
increasing the current regulators output we must first increase the
supply voltage and then the regulator itself. When we are decreasing the
current regulators voltage we must decrease the supply voltage after
changing the current regulators voltage.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 drivers/regulator/core.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 52 insertions(+), 2 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index fd22380..7ef69e5 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -2826,6 +2826,8 @@ static int regulator_set_voltage_unlocked(struct regulator *regulator,
 	int ret = 0;
 	int old_min_uV, old_max_uV;
 	int current_uV;
+	int best_supply_uV = 0;
+	int supply_change_uV = 0;
 
 	/* If we're setting the same range as last time the change
 	 * should be a noop (some cpufreq implementations use the same
@@ -2869,10 +2871,58 @@ static int regulator_set_voltage_unlocked(struct regulator *regulator,
 	if (ret < 0)
 		goto out2;
 
+	if (rdev->supply && (rdev->desc->min_dropout_uV ||
+				!rdev->desc->ops->get_voltage)) {
+		int current_supply_uV;
+		int selector;
+
+		selector = regulator_map_voltage(rdev, min_uV, max_uV);
+		if (selector < 0) {
+			ret = selector;
+			goto out2;
+		}
+
+		best_supply_uV = _regulator_list_voltage(regulator, selector, 0);
+		if (best_supply_uV < 0) {
+			ret = best_supply_uV;
+			goto out2;
+		}
+
+		best_supply_uV += rdev->desc->min_dropout_uV;
+
+		current_supply_uV = _regulator_get_voltage(rdev->supply->rdev);
+		if (current_supply_uV < 0) {
+			ret = current_supply_uV;
+			goto out2;
+		}
+
+		supply_change_uV = best_supply_uV - current_supply_uV;
+	}
+
+	if (supply_change_uV > 0) {
+		ret = regulator_set_voltage_unlocked(rdev->supply,
+				best_supply_uV, INT_MAX);
+		if (ret) {
+			dev_err(&rdev->dev, "Failed to increase supply voltage: %d\n",
+					ret);
+			goto out2;
+		}
+	}
+
 	ret = _regulator_do_set_voltage(rdev, min_uV, max_uV);
 	if (ret < 0)
 		goto out2;
 
+	if (supply_change_uV < 0) {
+		ret = regulator_set_voltage_unlocked(rdev->supply,
+				best_supply_uV, INT_MAX);
+		if (ret)
+			dev_warn(&rdev->dev, "Failed to decrease supply voltage: %d\n",
+					ret);
+		/* No need to fail here */
+		ret = 0;
+	}
+
 out:
 	return ret;
 out2:
@@ -2904,11 +2954,11 @@ int regulator_set_voltage(struct regulator *regulator, int min_uV, int max_uV)
 {
 	int ret = 0;
 
-	mutex_lock(&regulator->rdev->mutex);
+	regulator_lock_supply(regulator->rdev);
 
 	ret = regulator_set_voltage_unlocked(regulator, min_uV, max_uV);
 
-	mutex_unlock(&regulator->rdev->mutex);
+	regulator_unlock_supply(regulator->rdev);
 
 	return ret;
 }
-- 
2.6.1

[PATCH 3/3] ARM: i.MX6 Phytec PFLA02: Add supplies for the SoC internal regulators

[Sascha Hauer]

The SoC internal regulators for the CPU and the SoC come from the
DA9063 vdd_core and vdd_soc. Add this relationship to the device tree
so that the voltage drop on the SoC internal LDO regulators can be
minimized.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Mark Brown <broonie@kernel.org>
---
 arch/arm/boot/dts/imx6qdl-phytec-pfla02.dtsi | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/arm/boot/dts/imx6qdl-phytec-pfla02.dtsi b/arch/arm/boot/dts/imx6qdl-phytec-pfla02.dtsi
index d6d98d4..b879383 100644
--- a/arch/arm/boot/dts/imx6qdl-phytec-pfla02.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-phytec-pfla02.dtsi
@@ -379,6 +379,18 @@
 	status = "disabled";
 };
 
+&reg_arm {
+	vin-supply = <&vddcore_reg>;
+};
+
+&reg_pu {
+	vin-supply = <&vddsoc_reg>;
+};
+
+&reg_soc {
+	vin-supply = <&vddsoc_reg>;
+};
+
 &uart3 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_uart3>;
-- 
2.6.1