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

AngeloGioacchino Del Regno
2021-01-17T18:18:45Z

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

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 <bjorn.andersson@linaro.org>
>

Thank you!

> Regards,
> Bjorn
>