regulator: qcom-labibb: Implement pull-down, softstart, active discharge

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>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210119174421.226541-4-angelogioacchino.delregno@somainline.org
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/regulator/qcom-labibb-regulator.c b/drivers/regulator/qcom-labibb-regulator.c
index 0643713..4d68b69 100644 (file)
--- 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 {
@@ -120,6 +133,70 @@ 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,
@@ -128,8 +205,11 @@ static const struct regulator_ops qcom_labibb_ops = {
        .get_voltage_sel        = regulator_get_voltage_sel_regmap,
        .list_voltage           = regulator_list_voltage_linear,
        .map_voltage            = regulator_map_voltage_linear,
+       .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 = {
@@ -138,6 +218,10 @@ 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),
@@ -152,6 +236,7 @@ static const struct regulator_desc pmi8998_lab_desc = {
        .uV_step                = 100000,
        .n_voltages             = 16,
        .ops                    = &qcom_labibb_ops,
+       .of_parse_cb            = qcom_labibb_of_parse_cb,
 };
 
 static const struct regulator_desc pmi8998_ibb_desc = {
@@ -160,6 +245,14 @@ 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),
@@ -174,6 +267,7 @@ static const struct regulator_desc pmi8998_ibb_desc = {
        .uV_step                = 100000,
        .n_voltages             = 64,
        .ops                    = &qcom_labibb_ops,
+       .of_parse_cb            = qcom_labibb_of_parse_cb,
 };
 
 static const struct labibb_regulator_data pmi8998_labibb_data[] = {