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regulator: axp20x: add software based soft_start for AXP209 LDO3
In the past, there have been words on various lists that if LDO3 is disabled in u-boot, but enabled in the DTS, the axp209 driver would fail to continue/hang. Several enable/disable patches have been issues to devicetree's in both the kernel and u-boot to address this issue. What really happened however, was that the AXP209 shuts down without a notice and without setting an interrupt. This is caused when LDO3 gets overloaded, for example with large capacitors on the LDO3 output. Normally, we would expect that AXP209 would source 200 mA as per datasheet and set and trigger an interrupt when being overloaded. For some reason however, this does not happen. As a work-around, we use the soft-start constraint of the regulator node to first bring up the LDO3 to the lowest possible voltage and then enable the LDO. After that, we can set the requested voltage as usual. Combining this setting with the regulator-ramp-delay allows LDO3 to enable voltage slowly and staggered, potentially reducing overall inrush current. Signed-off-by: Olliver Schinagl <oliver@schinagl.nl> Signed-off-by: Priit Laes <plaes@plaes.org> Signed-off-by: Mark Brown <broonie@kernel.org>
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1 changed files with 56 additions and 1 deletions
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@ -14,6 +14,7 @@
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*/
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#include <linux/bitops.h>
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#include <linux/delay.h>
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#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/mfd/axp20x.h>
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@ -23,6 +24,7 @@
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#include <linux/platform_device.h>
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#include <linux/regmap.h>
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#include <linux/regulator/driver.h>
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#include <linux/regulator/machine.h>
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#include <linux/regulator/of_regulator.h>
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#define AXP20X_GPIO0_FUNC_MASK GENMASK(3, 0)
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@ -430,6 +432,59 @@ static int axp20x_set_ramp_delay(struct regulator_dev *rdev, int ramp)
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return regmap_update_bits(axp20x->regmap, reg, mask, cfg);
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}
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static int axp20x_regulator_enable_regmap(struct regulator_dev *rdev)
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{
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struct axp20x_dev *axp20x = rdev_get_drvdata(rdev);
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const struct regulator_desc *desc = rdev->desc;
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if (!rdev)
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return -EINVAL;
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switch (axp20x->variant) {
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case AXP209_ID:
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if ((desc->id == AXP20X_LDO3) &&
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rdev->constraints && rdev->constraints->soft_start) {
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int v_out;
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int ret;
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/*
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* On some boards, the LDO3 can be overloaded when
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* turning on, causing the entire PMIC to shutdown
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* without warning. Turning it on at the minimal voltage
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* and then setting the voltage to the requested value
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* works reliably.
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*/
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if (regulator_is_enabled_regmap(rdev))
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break;
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v_out = regulator_get_voltage_sel_regmap(rdev);
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if (v_out < 0)
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return v_out;
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if (v_out == 0)
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break;
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ret = regulator_set_voltage_sel_regmap(rdev, 0x00);
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/*
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* A small pause is needed between
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* setting the voltage and enabling the LDO to give the
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* internal state machine time to process the request.
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*/
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usleep_range(1000, 5000);
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ret |= regulator_enable_regmap(rdev);
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ret |= regulator_set_voltage_sel_regmap(rdev, v_out);
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return ret;
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}
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break;
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default:
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/* No quirks */
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break;
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}
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return regulator_enable_regmap(rdev);
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};
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static const struct regulator_ops axp20x_ops_fixed = {
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.list_voltage = regulator_list_voltage_linear,
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};
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@ -447,7 +502,7 @@ static const struct regulator_ops axp20x_ops = {
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.set_voltage_sel = regulator_set_voltage_sel_regmap,
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.get_voltage_sel = regulator_get_voltage_sel_regmap,
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.list_voltage = regulator_list_voltage_linear,
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.enable = regulator_enable_regmap,
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.enable = axp20x_regulator_enable_regmap,
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.disable = regulator_disable_regmap,
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.is_enabled = regulator_is_enabled_regmap,
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.set_ramp_delay = axp20x_set_ramp_delay,
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