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Subject[PATCH 3/7] regulator: qcom-labibb: Implement pull-down, softstart, active discharge
Date
Soft start is required to avoid inrush current during LAB ramp-up and
IBB ramp-down, protecting connected hardware to which we supply voltage.

Since soft start is configurable on both LAB and IBB regulators, it
was necessary to add two DT properties, respectively "qcom,soft-start-us"
to control LAB ramp-up and "qcom,discharge-resistor-kohms" to control
the discharge resistor for IBB ramp-down, which obviously brought the
need of implementing a of_parse callback for both regulators.

Finally, also implement pull-down mode in order to avoid unpredictable
behavior when the regulators are disabled (random voltage spikes etc).

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
---
drivers/regulator/qcom-labibb-regulator.c | 94 +++++++++++++++++++++++
1 file changed, 94 insertions(+)

diff --git a/drivers/regulator/qcom-labibb-regulator.c b/drivers/regulator/qcom-labibb-regulator.c
index c93d0d51cecb..21175e297c1f 100644
--- a/drivers/regulator/qcom-labibb-regulator.c
+++ b/drivers/regulator/qcom-labibb-regulator.c
@@ -29,12 +29,23 @@
#define LABIBB_STATUS1_VREG_OK_BIT BIT(7)
#define LABIBB_CONTROL_ENABLE BIT(7)

+#define REG_LABIBB_PD_CTL 0x47
+ #define LAB_PD_CTL_MASK GENMASK(1, 0)
+ #define IBB_PD_CTL_MASK (BIT(0) | BIT(7))
+ #define LAB_PD_CTL_STRONG_PULL BIT(0)
+ #define IBB_PD_CTL_HALF_STRENGTH BIT(0)
+ #define IBB_PD_CTL_EN BIT(7)
+
#define REG_LABIBB_CURRENT_LIMIT 0x4b
#define LAB_CURRENT_LIMIT_MASK GENMASK(2, 0)
#define IBB_CURRENT_LIMIT_MASK GENMASK(4, 0)
#define LAB_CURRENT_LIMIT_OVERRIDE_EN BIT(3)
#define LABIBB_CURRENT_LIMIT_EN BIT(7)

+#define REG_IBB_PWRUP_PWRDN_CTL_1 0x58
+ #define IBB_CTL_1_DISCHARGE_EN BIT(2)
+
+#define REG_LABIBB_SOFT_START_CTL 0x5f
#define REG_LABIBB_SEC_ACCESS 0xd0
#define LABIBB_SEC_UNLOCK_CODE 0xa5

@@ -60,6 +71,8 @@ struct labibb_regulator {
struct labibb_current_limits uA_limits;
u16 base;
u8 type;
+ u8 dischg_sel;
+ u8 soft_start_sel;
};

struct labibb_regulator_data {
@@ -119,6 +132,70 @@ static int qcom_labibb_get_current_limit(struct regulator_dev *rdev)
return (cur_step * lim->uA_step) + lim->uA_min;
}

+static int qcom_labibb_set_soft_start(struct regulator_dev *rdev)
+{
+ struct labibb_regulator *vreg = rdev_get_drvdata(rdev);
+ u32 val = 0;
+
+ if (vreg->type == QCOM_IBB_TYPE)
+ val = vreg->dischg_sel;
+ else
+ val = vreg->soft_start_sel;
+
+ return regmap_write(rdev->regmap, rdev->desc->soft_start_reg, val);
+}
+
+static int qcom_labibb_get_table_sel(const int *table, int sz, u32 value)
+{
+ int i;
+
+ for (i = 0; i < sz; i++)
+ if (table[i] == value)
+ return i;
+ return -EINVAL;
+}
+
+/* IBB discharge resistor values in KOhms */
+static const int dischg_resistor_values[] = { 300, 64, 32, 16 };
+
+/* Soft start time in microseconds */
+static const int soft_start_values[] = { 200, 400, 600, 800 };
+
+static int qcom_labibb_of_parse_cb(struct device_node *np,
+ const struct regulator_desc *desc,
+ struct regulator_config *config)
+{
+ struct labibb_regulator *vreg = config->driver_data;
+ u32 dischg_kohms, soft_start_time;
+ int ret;
+
+ ret = of_property_read_u32(np, "qcom,discharge-resistor-kohms",
+ &dischg_kohms);
+ if (ret)
+ dischg_kohms = 300;
+
+ ret = qcom_labibb_get_table_sel(dischg_resistor_values,
+ ARRAY_SIZE(dischg_resistor_values),
+ dischg_kohms);
+ if (ret < 0)
+ return ret;
+ vreg->dischg_sel = (u8)ret;
+
+ ret = of_property_read_u32(np, "qcom,soft-start-us",
+ &soft_start_time);
+ if (ret)
+ soft_start_time = 200;
+
+ ret = qcom_labibb_get_table_sel(soft_start_values,
+ ARRAY_SIZE(soft_start_values),
+ soft_start_time);
+ if (ret < 0)
+ return ret;
+ vreg->soft_start_sel = (u8)ret;
+
+ return 0;
+}
+
static const struct regulator_ops qcom_labibb_ops = {
.enable = regulator_enable_regmap,
.disable = regulator_disable_regmap,
@@ -127,8 +204,11 @@ static const struct regulator_ops qcom_labibb_ops = {
.get_voltage_sel = regulator_get_voltage_sel_regmap,
.list_voltage = regulator_list_voltage_linear_range,
.map_voltage = regulator_map_voltage_linear_range,
+ .set_active_discharge = regulator_set_active_discharge_regmap,
+ .set_pull_down = regulator_set_pull_down_regmap,
.set_current_limit = qcom_labibb_set_current_limit,
.get_current_limit = qcom_labibb_get_current_limit,
+ .set_soft_start = qcom_labibb_set_soft_start,
};

static const struct regulator_desc pmi8998_lab_desc = {
@@ -137,6 +217,10 @@ static const struct regulator_desc pmi8998_lab_desc = {
.enable_val = LABIBB_CONTROL_ENABLE,
.enable_time = LAB_ENABLE_TIME,
.poll_enabled_time = LABIBB_POLL_ENABLED_TIME,
+ .soft_start_reg = (PMI8998_LAB_REG_BASE + REG_LABIBB_SOFT_START_CTL),
+ .pull_down_reg = (PMI8998_LAB_REG_BASE + REG_LABIBB_PD_CTL),
+ .pull_down_mask = LAB_PD_CTL_MASK,
+ .pull_down_val_on = LAB_PD_CTL_STRONG_PULL,
.vsel_reg = (PMI8998_LAB_REG_BASE + REG_LABIBB_VOLTAGE),
.vsel_mask = LAB_VOLTAGE_SET_MASK,
.apply_reg = (PMI8998_LAB_REG_BASE + REG_LABIBB_VOLTAGE),
@@ -153,6 +237,7 @@ static const struct regulator_desc pmi8998_lab_desc = {
.n_linear_ranges = 1,
.n_voltages = 16,
.ops = &qcom_labibb_ops,
+ .of_parse_cb = qcom_labibb_of_parse_cb,
};

static const struct regulator_desc pmi8998_ibb_desc = {
@@ -161,6 +246,14 @@ static const struct regulator_desc pmi8998_ibb_desc = {
.enable_val = LABIBB_CONTROL_ENABLE,
.enable_time = IBB_ENABLE_TIME,
.poll_enabled_time = LABIBB_POLL_ENABLED_TIME,
+ .soft_start_reg = (PMI8998_IBB_REG_BASE + REG_LABIBB_SOFT_START_CTL),
+ .active_discharge_off = 0,
+ .active_discharge_on = IBB_CTL_1_DISCHARGE_EN,
+ .active_discharge_mask = IBB_CTL_1_DISCHARGE_EN,
+ .active_discharge_reg = (PMI8998_IBB_REG_BASE + REG_IBB_PWRUP_PWRDN_CTL_1),
+ .pull_down_reg = (PMI8998_IBB_REG_BASE + REG_LABIBB_PD_CTL),
+ .pull_down_mask = IBB_PD_CTL_MASK,
+ .pull_down_val_on = IBB_PD_CTL_HALF_STRENGTH | IBB_PD_CTL_EN,
.vsel_reg = (PMI8998_IBB_REG_BASE + REG_LABIBB_VOLTAGE),
.vsel_mask = IBB_VOLTAGE_SET_MASK,
.apply_reg = (PMI8998_IBB_REG_BASE + REG_LABIBB_VOLTAGE),
@@ -177,6 +270,7 @@ static const struct regulator_desc pmi8998_ibb_desc = {
.n_linear_ranges = 1,
.n_voltages = 64,
.ops = &qcom_labibb_ops,
+ .of_parse_cb = qcom_labibb_of_parse_cb,
};

static const struct labibb_regulator_data pmi8998_labibb_data[] = {
--
2.29.2
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