Re: [PATCH v2 3/7] regulator: qcom-labibb: Implement pull-down, softstart, active discharge

Il 15/01/21 05:53, Bjorn Andersson ha scritto:

On Wed 13 Jan 13:42 CST 2021, AngeloGioacchino Del Regno wrote:

quoted

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 <redacted>
---
  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 d364f54ad294..38ab1eba1c59 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 {

@@ -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;

Nit, if you just initialize dischg_kohms to 300 during definition you
can rely on of_property_read_u32() not updating the value on failure...

I can change it if that's really necessary, I did it like this in an
attempt of spoon-feed the logic to the reader, but perhaps just
initializing it during definition would achieve the same, anyway.

Should I?

That said, I think this patch looks good.

Reviewed-by: Bjorn Andersson <redacted>

Thank you!

Regards,
Bjorn