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Message-ID: <CAE-0n51yD6GG9eTn0tivqg0GUme5ONOabQrM0KBDjs5n8WKMYQ@mail.gmail.com>
Date:   Thu, 28 Oct 2021 13:19:30 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Satya Priya <quic_c_skakit@...cinc.com>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>, collinsd@...eurora.org,
        subbaram@...eaurora.org, Das Srinagesh <gurus@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, Lee Jones <lee.jones@...aro.org>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3 3/4] regulator: Add a regulator driver for the PM8008 PMIC

Quoting Satya Priya (2021-10-28 08:14:31)
> diff --git a/drivers/regulator/qcom-pm8008-regulator.c b/drivers/regulator/qcom-pm8008-regulator.c
> new file mode 100644
> index 0000000..74ba682
> --- /dev/null
> +++ b/drivers/regulator/qcom-pm8008-regulator.c
> @@ -0,0 +1,269 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright (c) 2021, The Linux Foundation. All rights reserved. */
> +
> +#include <linux/device.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/driver.h>
> +#include <linux/regulator/machine.h>
> +#include <linux/regulator/of_regulator.h>
> +
> +#define STARTUP_DELAY_USEC             20
> +#define VSET_STEP_MV                   8
> +#define VSET_STEP_UV                   (VSET_STEP_MV * 1000)
> +
> +#define LDO_ENABLE_REG(base)           (base + 0x46)

Add parenthesis around base as well ((base) + 0x46)

> +#define ENABLE_BIT                     BIT(7)
> +
> +#define LDO_STATUS1_REG(base)          (base + 0x08)
> +#define VREG_READY_BIT                 BIT(7)
> +
> +#define LDO_VSET_LB_REG(base)          (base + 0x40)
> +
> +#define LDO_STEPPER_CTL_REG(base)      (base + 0x3b)
> +#define DEFAULT_VOLTAGE_STEPPER_RATE   38400
> +#define STEP_RATE_MASK                 GENMASK(1, 0)
> +
> +struct regulator_data {
> +       const char      *name;
> +       const char      *supply_name;
> +       int             min_uv;
> +       int             max_uv;
> +       int             min_dropout_uv;
> +};
> +
> +struct pm8008_regulator {
> +       struct device           *dev;
> +       struct regmap           *regmap;
> +       struct regulator_desc   rdesc;
> +       struct regulator_dev    *rdev;
> +       struct device_node      *of_node;

This isn't used outside of probe so please drop it. Same goes for any
other struct member that we don't need to keep around beyond probe. Drop
them. rdev?

> +       u16                     base;
> +       int                     step_rate;
> +};
> +
> +static const struct regulator_data reg_data[] = {
> +       /* name  parent      min_uv  max_uv  headroom_uv */
> +       { "l1", "vdd_l1_l2",  528000, 1504000, 225000 },
> +       { "l2", "vdd_l1_l2",  528000, 1504000, 225000 },
> +       { "l3", "vdd_l3_l4", 1504000, 3400000, 200000 },
> +       { "l4", "vdd_l3_l4", 1504000, 3400000, 200000 },
> +       { "l5", "vdd_l5",    1504000, 3400000, 300000 },
> +       { "l6", "vdd_l6",    1504000, 3400000, 300000 },
> +       { "l7", "vdd_l7",    1504000, 3400000, 300000 },
> +       { }
> +};
> +
> +static int pm8008_regulator_get_voltage(struct regulator_dev *rdev)
> +{
> +       struct pm8008_regulator *pm8008_reg = rdev_get_drvdata(rdev);
> +       __le16 mV;
> +       int rc;
> +
> +       rc = regmap_bulk_read(pm8008_reg->regmap,
> +                       LDO_VSET_LB_REG(pm8008_reg->base), (void *)&mV, 2);
> +       if (rc < 0) {
> +               dev_err(pm8008_reg->dev,
> +                                       "failed to read regulator voltage rc=%d\n", rc);

Put it all on one line?

> +               return rc;
> +       }
> +
> +       return le16_to_cpu(mV) * 1000;
> +}
> +
> +static inline int pm8008_write_voltage(struct pm8008_regulator *pm8008_reg,
> +                                       int min_uv, int max_uv)
> +{
> +       int rc, mv;
> +       u16 vset_raw;
> +
> +       mv = DIV_ROUND_UP(min_uv, 1000);
> +
> +       /*
> +        * Each LSB of regulator is 1mV and the voltage setpoint
> +        * should be multiple of 8mV(step).
> +        */
> +       mv = DIV_ROUND_UP(mv, VSET_STEP_MV) * VSET_STEP_MV;
> +       if (mv * 1000 > max_uv) {
> +               dev_err(pm8008_reg->dev,
> +                       "requested voltage (%d uV) above maximum limit (%d uV)\n",
> +                               mv*1000, max_uv);
> +               return -EINVAL;
> +       }
> +
> +       vset_raw = cpu_to_le16(mv);
> +
> +       rc = regmap_bulk_write(pm8008_reg->regmap,
> +                       LDO_VSET_LB_REG(pm8008_reg->base),
> +                       (const void *)&vset_raw, sizeof(vset_raw));
> +       if (rc < 0) {
> +               dev_err(pm8008_reg->dev, "failed to write voltage rc=%d\n", rc);

If this uses the regulator_dev::dev then we'll know which regulator is
failing, instead of just that some regulator failed inside the PMIC.

> +               return rc;
> +       }
> +
> +       return 0;
> +}
> +
> +static int pm8008_regulator_set_voltage_time(struct regulator_dev *rdev,
> +                               int old_uV, int new_uv)
> +{
> +       struct pm8008_regulator *pm8008_reg = rdev_get_drvdata(rdev);
> +
> +       return DIV_ROUND_UP(abs(new_uv - old_uV), pm8008_reg->step_rate);
> +}
> +
> +static int pm8008_regulator_set_voltage(struct regulator_dev *rdev,
> +                               int min_uv, int max_uv, unsigned int *selector)
> +{
> +       struct pm8008_regulator *pm8008_reg = rdev_get_drvdata(rdev);
> +       int rc;
> +
> +       rc = pm8008_write_voltage(pm8008_reg, min_uv, max_uv);
> +       if (rc < 0)
> +               return rc;
> +
> +       *selector = DIV_ROUND_UP(min_uv - pm8008_reg->rdesc.min_uV,
> +                               VSET_STEP_UV);
> +
> +       dev_dbg(pm8008_reg->dev, "voltage set to %d\n", min_uv);
> +       return 0;
> +}
> +
> +static const struct regulator_ops pm8008_regulator_ops = {
> +       .enable                 = regulator_enable_regmap,
> +       .disable                = regulator_disable_regmap,
> +       .is_enabled             = regulator_is_enabled_regmap,
> +       .set_voltage            = pm8008_regulator_set_voltage,

Can we use set_voltage_sel instead?

> +       .get_voltage            = pm8008_regulator_get_voltage,
> +       .list_voltage           = regulator_list_voltage_linear,
> +       .set_voltage_time       = pm8008_regulator_set_voltage_time,
> +};
> +
> +static int pm8008_regulator_of_parse(struct device_node *node,
> +                       const struct regulator_desc *desc,
> +                       struct regulator_config *config)
> +{
> +       struct pm8008_regulator *pm8008_reg = config->driver_data;
> +       struct device *dev = config->dev;
> +       int rc;
> +       u8 reg;
> +
> +       rc = of_property_read_u32(node, "regulator-min-dropout-voltage-microvolt",
> +                       &pm8008_reg->rdesc.min_dropout_uV);
> +       if (rc) {
> +               dev_err(dev, "failed to read min-dropout voltage rc=%d\n", rc);
> +               return rc;
> +       }
> +
> +       /* get slew rate */
> +       rc = regmap_bulk_read(pm8008_reg->regmap,
> +                       LDO_STEPPER_CTL_REG(pm8008_reg->base), (void *)&reg, 1);

Just make reg unsigned int to avoid the cast.

> +       if (rc < 0) {
> +               dev_err(dev, "%s: failed to read step rate configuration rc=%d\n",
> +                               pm8008_reg->rdesc.name, rc);
> +               return rc;
> +       }

	reg &= STEP_RATE_MASK;
	pm8008_reg->step_rate = DEFAULT_VOLTAGE_STEPPER_RATE >> reg;

> +       pm8008_reg->step_rate
> +                       = DEFAULT_VOLTAGE_STEPPER_RATE >> (reg & STEP_RATE_MASK);
> +
> +       return 0;
> +}
> +
> +static int pm8008_regulator_probe(struct platform_device *pdev)
> +{
> +       struct device *dev = &pdev->dev;
> +       struct device_node *node = pdev->dev.of_node;
> +       struct pm8008_regulator *pm8008_reg;
> +       struct regmap *regmap;
> +       struct regulator_config reg_config = {};
> +       const struct regulator_data *reg;
> +       struct regulator_init_data *init_data;
> +       int rc;
> +       u32 base;
> +
> +       regmap = dev_get_regmap(dev->parent, NULL);
> +       if (!regmap) {
> +               dev_err(dev, "parent regmap is missing\n");
> +               return -EINVAL;
> +       }
> +
> +       for (reg = &reg_data[0]; reg->name; reg++) {
> +               pm8008_reg = devm_kzalloc(dev, sizeof(*pm8008_reg), GFP_KERNEL);
> +
> +               pm8008_reg->regmap = regmap;
> +
> +               pm8008_reg->of_node = of_get_child_by_name(node, reg->name);

This of_node reference needs to be put somewhere.

> +               if (!pm8008_reg->of_node) {
> +                       dev_err(dev, "child node %s not found\n", reg->name);
> +                       return -ENODEV;
> +               }
> +
> +               pm8008_reg->dev = dev;
> +
> +               rc = of_property_read_u32(pm8008_reg->of_node, "reg", &base);
> +               if (rc < 0) {
> +                       dev_err(dev, "%s: failed to get regulator base rc=%d\n",
> +                                               reg->name, rc);
> +                       return rc;
> +               }
> +               pm8008_reg->base = base;
> +
> +               init_data = of_get_regulator_init_data(dev, pm8008_reg->of_node,
> +                                                       &pm8008_reg->rdesc);

Is this necessary?

> +               if (!init_data) {
> +                       dev_err(dev, "%s: failed to get regulator data\n", reg->name);
> +                       return -ENODATA;
> +               }
> +
> +               pm8008_reg->rdesc.type = REGULATOR_VOLTAGE;
> +               pm8008_reg->rdesc.ops = &pm8008_regulator_ops;
> +               pm8008_reg->rdesc.name = init_data->constraints.name;
> +               pm8008_reg->rdesc.supply_name = reg->supply_name;
> +               pm8008_reg->rdesc.of_match = reg->name;
> +               pm8008_reg->rdesc.of_parse_cb = pm8008_regulator_of_parse;
> +               pm8008_reg->rdesc.uV_step = VSET_STEP_UV;
> +               pm8008_reg->rdesc.min_uV = reg->min_uv;
> +               pm8008_reg->rdesc.n_voltages
> +                       = ((reg->max_uv - reg->min_uv)
> +                               / pm8008_reg->rdesc.uV_step) + 1;
> +
> +               pm8008_reg->rdesc.enable_reg = LDO_ENABLE_REG(base);
> +               pm8008_reg->rdesc.enable_mask = ENABLE_BIT;
> +               pm8008_reg->rdesc.min_dropout_uV = reg->min_dropout_uv;
> +
> +               init_data->constraints.input_uV = init_data->constraints.max_uV;
> +               reg_config.dev = dev;
> +               reg_config.init_data = init_data;
> +               reg_config.driver_data = pm8008_reg;
> +               reg_config.of_node = pm8008_reg->of_node;

I think we don't need to do this?

> +
> +               return PTR_ERR_OR_ZERO(devm_regulator_register(dev, &pm8008_reg->rdesc,
> +                                                               &reg_config));

Why are we returning here? Shouldn't we check return value and only
return on failure and otherwise continue with registering the rest of
the regulators?

> +       }
> +
> +       return 0;
> +}
> +

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