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

Bjorn Andersson
2021-01-15T04:54:01Z

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

> 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 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...

That said, I think this patch looks good.

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Regards,
Bjorn