Re: [PATCH v2 2/7] regulator: qcom-labibb: Implement current limiting

Bjorn Andersson
2021-01-15T04:38:44Z

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

> LAB and IBB regulators can be current-limited by setting the
> appropriate registers, but this operation is granted only after
> sending an unlock code for secure access.
>
> Besides the secure access, it would be possible to use the
> regmap helper for get_current_limit, as there is no security
> blocking reads, but I chose not to as to avoid having a very
> big array containing current limits, especially for IBB.
>
> That said, these regulators support current limiting for:
> - LAB (pos): 200-1600mA, with 200mA per step (8 steps),
> - IBB (neg): 0-1550mA, with 50mA per step (32 steps).
>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
> ---
> drivers/regulator/qcom-labibb-regulator.c | 92 +++++++++++++++++++++++
> 1 file changed, 92 insertions(+)
>
> diff --git a/drivers/regulator/qcom-labibb-regulator.c b/drivers/regulator/qcom-labibb-regulator.c
> index 9f51c96f16fb..d364f54ad294 100644
> --- a/drivers/regulator/qcom-labibb-regulator.c
> +++ b/drivers/regulator/qcom-labibb-regulator.c
> @@ -29,6 +29,15 @@
> #define LABIBB_STATUS1_VREG_OK_BIT BIT(7)
> #define LABIBB_CONTROL_ENABLE 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_LABIBB_SEC_ACCESS 0xd0
> + #define LABIBB_SEC_UNLOCK_CODE 0xa5
> +
> #define LAB_ENABLE_CTL_MASK BIT(7)
> #define IBB_ENABLE_CTL_MASK (BIT(7) | BIT(6))
>
> @@ -37,11 +46,18 @@
> #define IBB_ENABLE_TIME (LABIBB_OFF_ON_DELAY * 10)
> #define LABIBB_POLL_ENABLED_TIME 1000
>
> +struct labibb_current_limits {
> + u32 uA_min;
> + u32 uA_step;
> + u8 ovr_val;
> +};
> +
> struct labibb_regulator {
> struct regulator_desc desc;
> struct device *dev;
> struct regmap *regmap;
> struct regulator_dev *rdev;
> + struct labibb_current_limits uA_limits;
> u16 base;
> u8 type;
> };
> @@ -53,6 +69,57 @@ struct labibb_regulator_data {
> const struct regulator_desc *desc;
> };
>
> +static int qcom_labibb_set_current_limit(struct regulator_dev *rdev,
> + int min_uA, int max_uA)

I was under the impression that a regulator driver should either
implement set_voltage_* or set_current_limit, depending on which type of
regulator it is - i.e. this API isn't supposed to be setting the current
limit. Perhaps I'm wrong though?

> +{
> + struct labibb_regulator *vreg = rdev_get_drvdata(rdev);
> + struct regulator_desc *desc = &vreg->desc;
> + struct labibb_current_limits *lim = &vreg->uA_limits;
> + u32 mask, val;
> + int i, ret, sel = -1;
> +
> + if (min_uA < lim->uA_min || max_uA < lim->uA_min)
> + return -EINVAL;
> +
> + for (i = 0; i < desc->n_current_limits; i++) {
> + int uA_limit = (lim->uA_step * i) + lim->uA_min;
> +
> + if (max_uA >= uA_limit && min_uA <= uA_limit)

I presume here you rely on the client passing something like min_uA = 0
and max_uA 500? Because if the client where to
regulator_set_current_limit(475, 475) you will pass through this loop
without finding a match, but 450 would probably be a really good
pick...

But what does it even mean to pass min/max uA for a current limit?

That said, I think this loop would be better expressed as a single
subtract uA_min and then divide by uA_step.

Apart from that, this patch looks good to me.

Regards,
Bjorn

> + sel = i;
> + }
> + if (sel < 0)
> + return -EINVAL;
> +
> + /* Current limit setting needs secure access */
> + ret = regmap_write(vreg->regmap, vreg->base + REG_LABIBB_SEC_ACCESS,
> + LABIBB_SEC_UNLOCK_CODE);
> + if (ret)
> + return ret;
> +
> + mask = desc->csel_mask | lim->ovr_val;
> + mask |= LABIBB_CURRENT_LIMIT_EN;
> + val = (u32)sel | lim->ovr_val;
> + val |= LABIBB_CURRENT_LIMIT_EN;
> +
> + return regmap_update_bits(vreg->regmap, desc->csel_reg, mask, val);
> +}
> +
> +static int qcom_labibb_get_current_limit(struct regulator_dev *rdev)
> +{
> + struct labibb_regulator *vreg = rdev_get_drvdata(rdev);
> + struct regulator_desc *desc = &vreg->desc;
> + struct labibb_current_limits *lim = &vreg->uA_limits;
> + unsigned int cur_step;
> + int ret;
> +
> + ret = regmap_read(vreg->regmap, desc->csel_reg, &cur_step);
> + if (ret)
> + return ret;
> + cur_step &= desc->csel_mask;
> +
> + return (cur_step * lim->uA_step) + lim->uA_min;
> +}
> +
> static const struct regulator_ops qcom_labibb_ops = {
> .enable = regulator_enable_regmap,
> .disable = regulator_disable_regmap,
> @@ -61,6 +128,8 @@ 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_current_limit = qcom_labibb_set_current_limit,
> + .get_current_limit = qcom_labibb_get_current_limit,
> };
>
> static const struct regulator_desc pmi8998_lab_desc = {
> @@ -73,6 +142,9 @@ static const struct regulator_desc pmi8998_lab_desc = {
> .vsel_mask = LAB_VOLTAGE_SET_MASK,
> .apply_reg = (PMI8998_LAB_REG_BASE + REG_LABIBB_VOLTAGE),
> .apply_bit = LABIBB_VOLTAGE_OVERRIDE_EN,
> + .csel_reg = (PMI8998_LAB_REG_BASE + REG_LABIBB_CURRENT_LIMIT),
> + .csel_mask = LAB_CURRENT_LIMIT_MASK,
> + .n_current_limits = 8,
> .off_on_delay = LABIBB_OFF_ON_DELAY,
> .owner = THIS_MODULE,
> .type = REGULATOR_VOLTAGE,
> @@ -94,6 +166,9 @@ static const struct regulator_desc pmi8998_ibb_desc = {
> .vsel_mask = IBB_VOLTAGE_SET_MASK,
> .apply_reg = (PMI8998_IBB_REG_BASE + REG_LABIBB_VOLTAGE),
> .apply_bit = LABIBB_VOLTAGE_OVERRIDE_EN,
> + .csel_reg = (PMI8998_IBB_REG_BASE + REG_LABIBB_CURRENT_LIMIT),
> + .csel_mask = IBB_CURRENT_LIMIT_MASK,
> + .n_current_limits = 32,
> .off_on_delay = LABIBB_OFF_ON_DELAY,
> .owner = THIS_MODULE,
> .type = REGULATOR_VOLTAGE,
> @@ -167,6 +242,23 @@ static int qcom_labibb_regulator_probe(struct platform_device *pdev)
> vreg->base = reg_data->base;
> vreg->type = reg_data->type;
>
> + switch (vreg->type) {
> + case QCOM_LAB_TYPE:
> + /* LAB Limits: 200-1600mA */
> + vreg->uA_limits.uA_min = 200000;
> + vreg->uA_limits.uA_step = 200000;
> + vreg->uA_limits.ovr_val = LAB_CURRENT_LIMIT_OVERRIDE_EN;
> + break;
> + case QCOM_IBB_TYPE:
> + /* IBB Limits: 0-1550mA */
> + vreg->uA_limits.uA_min = 0;
> + vreg->uA_limits.uA_step = 50000;
> + vreg->uA_limits.ovr_val = 0; /* No override bit */
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> memcpy(&vreg->desc, reg_data->desc, sizeof(vreg->desc));
> vreg->desc.of_match = reg_data->name;
> vreg->desc.name = reg_data->name;
> --
> 2.29.2
>