Changing voltage and enabling regulator might require delays so the regulator stabilizes at expected level.
Add support for "regulator-ramp-delay" binding which can introduce required time to both enabling the regulator and to changing the voltage.
Signed-off-by: Krzysztof Kozlowski krzk@kernel.org Tested-by: Anand Moon linux.amoon@gmail.com --- .../regulator/regulator.txt | 2 + drivers/power/regulator/regulator-uclass.c | 47 ++++++++++++++++++- include/power/regulator.h | 2 + 3 files changed, 49 insertions(+), 2 deletions(-)
diff --git a/doc/device-tree-bindings/regulator/regulator.txt b/doc/device-tree-bindings/regulator/regulator.txt index 65b69c427899..4ba642b7c77f 100644 --- a/doc/device-tree-bindings/regulator/regulator.txt +++ b/doc/device-tree-bindings/regulator/regulator.txt @@ -35,6 +35,7 @@ Optional properties: - regulator-max-microamp: a maximum allowed Current value - regulator-always-on: regulator should never be disabled - regulator-boot-on: enabled by bootloader/firmware +- regulator-ramp-delay: ramp delay for regulator (in uV/us)
Note The "regulator-name" constraint is used for setting the device's uclass @@ -60,4 +61,5 @@ ldo0 { regulator-max-microamp = <100000>; regulator-always-on; regulator-boot-on; + regulator-ramp-delay = <12000>; }; diff --git a/drivers/power/regulator/regulator-uclass.c b/drivers/power/regulator/regulator-uclass.c index 6f355b969a6d..9118b8eb39e3 100644 --- a/drivers/power/regulator/regulator-uclass.c +++ b/drivers/power/regulator/regulator-uclass.c @@ -35,10 +35,22 @@ int regulator_get_value(struct udevice *dev) return ops->get_value(dev); }
+static void regulator_set_value_ramp_delay(struct udevice *dev, int old_uV, + int new_uV, unsigned int ramp_delay) +{ + int delay = DIV_ROUND_UP(abs(new_uV - old_uV), ramp_delay); + + debug("regulator %s: delay %u us (%d uV -> %d uV)\n", dev->name, delay, + old_uV, new_uV); + + udelay(delay); +} + int regulator_set_value(struct udevice *dev, int uV) { const struct dm_regulator_ops *ops = dev_get_driver_ops(dev); struct dm_regulator_uclass_platdata *uc_pdata; + int ret, old_uV = uV, is_enabled = 0;
uc_pdata = dev_get_uclass_platdata(dev); if (uc_pdata->min_uV != -ENODATA && uV < uc_pdata->min_uV) @@ -49,7 +61,20 @@ int regulator_set_value(struct udevice *dev, int uV) if (!ops || !ops->set_value) return -ENOSYS;
- return ops->set_value(dev, uV); + if (uc_pdata->ramp_delay) { + is_enabled = regulator_get_enable(dev); + old_uV = regulator_get_value(dev); + } + + ret = ops->set_value(dev, uV); + + if (!ret) { + if (uc_pdata->ramp_delay && old_uV > 0 && is_enabled) + regulator_set_value_ramp_delay(dev, old_uV, uV, + uc_pdata->ramp_delay); + } + + return ret; }
/* @@ -107,6 +132,7 @@ int regulator_set_enable(struct udevice *dev, bool enable) { const struct dm_regulator_ops *ops = dev_get_driver_ops(dev); struct dm_regulator_uclass_platdata *uc_pdata; + int ret, old_enable = 0;
if (!ops || !ops->set_enable) return -ENOSYS; @@ -115,7 +141,22 @@ int regulator_set_enable(struct udevice *dev, bool enable) if (!enable && uc_pdata->always_on) return -EACCES;
- return ops->set_enable(dev, enable); + if (uc_pdata->ramp_delay) + old_enable = regulator_get_enable(dev); + + ret = ops->set_enable(dev, enable); + if (!ret) { + if (uc_pdata->ramp_delay && !old_enable && enable) { + int uV = regulator_get_value(dev); + + if (uV > 0) { + regulator_set_value_ramp_delay(dev, 0, uV, + uc_pdata->ramp_delay); + } + } + } + + return ret; }
int regulator_set_enable_if_allowed(struct udevice *dev, bool enable) @@ -335,6 +376,8 @@ static int regulator_pre_probe(struct udevice *dev) -ENODATA); uc_pdata->always_on = dev_read_bool(dev, "regulator-always-on"); uc_pdata->boot_on = dev_read_bool(dev, "regulator-boot-on"); + uc_pdata->ramp_delay = dev_read_u32_default(dev, "regulator-ramp-delay", + 0);
/* Those values are optional (-ENODATA if unset) */ if ((uc_pdata->min_uV != -ENODATA) && diff --git a/include/power/regulator.h b/include/power/regulator.h index 314160a894b7..6c6e2cd4f996 100644 --- a/include/power/regulator.h +++ b/include/power/regulator.h @@ -150,6 +150,7 @@ enum regulator_flag { * @always_on* - bool type, true or false * @boot_on* - bool type, true or false * TODO(sjg@chromium.org): Consider putting the above two into @flags + * @ramp_delay - Time to settle down after voltage change (unit: uV/us) * @flags: - flags value (see REGULATOR_FLAG_...) * @name** - fdt regulator name - should be taken from the device tree * ctrl_reg: - Control register offset used to enable/disable regulator @@ -169,6 +170,7 @@ struct dm_regulator_uclass_platdata { int max_uV; int min_uA; int max_uA; + unsigned int ramp_delay; bool always_on; bool boot_on; const char *name;