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Date: Fri, 22 Oct 2021 17:58:34 +0530
From: skakit@...eaurora.org
To: Stephen Boyd <swboyd@...omium.org>
Cc: Bjorn Andersson <bjorn.andersson@...aro.org>,
Rob Herring <robh+dt@...nel.org>,
Lee Jones <lee.jones@...aro.org>,
Liam Girdwood <lgirdwood@...il.com>,
Mark Brown <broonie@...nel.org>,
Das Srinagesh <gurus@...eaurora.org>,
linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, mka@...omium.org,
collinsd@...eaurora.org, subbaram@...eaurora.org,
kgunda@...eaurora.org
Subject: Re: [PATCH V2 3/4] regulator: Add a regulator driver for the PM8008
PMIC
On 2021-10-06 00:05, Stephen Boyd wrote:
> Quoting Satya Priya (2021-09-30 21:00:58)
>> diff --git a/drivers/regulator/qcom-pm8008-regulator.c
>> b/drivers/regulator/qcom-pm8008-regulator.c
>> new file mode 100644
>> index 0000000..5dacaa4
>> --- /dev/null
>> +++ b/drivers/regulator/qcom-pm8008-regulator.c
>> @@ -0,0 +1,320 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/* Copyright (c) 2021, The Linux Foundation. All rights reserved. */
>> +
>> +#include <linux/delay.h>
>
> Is this include used?
>
No will remove.
>> +#include <linux/device.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/module.h>
>> +#include <linux/mutex.h>
>
> Is this include used?
>
No
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/of_irq.h>
>
> Is this include used?
>
No
>> +#include <linux/pm.h>
>
> Is this include used?
>
No
>> +#include <linux/platform_device.h>
>> +#include <linux/regmap.h>
>> +#include <linux/string.h>
>
> Is this include used? Probably should just be kernel.h?
>
string.h is not used , will change it as kernel.h
>> +#include <linux/regulator/driver.h>
>> +#include <linux/regulator/machine.h>
>> +#include <linux/regulator/of_regulator.h>
>
> Is this include used?
>
Yes it is used. For of_get_regulator_init_data().
>> +
>> +#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)
>> +#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 STEP_RATE_MASK GENMASK(1, 0)
>> +
>> +#define PM8008_MAX_LDO 7
>
> Drop define.
>
ok.
>> +
>> +struct regulator_data {
>> + char *name;
>
> const?
>
ok
>> + char *supply_name;
>
> const?
>
ok
>> + 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;
>> + u16 base;
>> + int step_rate;
>> +};
>> +
>> +static const struct regulator_data reg_data[PM8008_MAX_LDO] = {
>
> Use [] instead of PM8008_MAX_LDO.
>
Ok.
>> + /* 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},
>
> Nitpick: Put a space after { and before } to match kernel style.
>
Okay.
>> +};
>> +
>> +static int pm8008_read(struct regmap *regmap, u16 reg, u8 *val, int
>> count)
>> +{
>> + int rc;
>> +
>> + rc = regmap_bulk_read(regmap, reg, val, count);
>> + if (rc < 0)
>> + pr_err("failed to read %#x, rc=%d\n", reg, rc);
>> +
>> + return rc;
>> +}
>> +
>> +static int pm8008_write(struct regmap *regmap, u16 reg, u8 *val, int
>> count)
>> +{
>> + int rc;
>> +
>> + pr_debug("Writing [%*ph] from address %#x\n", count, val,
>> reg);
>
> Don't we already have regmap debugging facilities for this? Why
> duplicate it in this driver?
>
>> + rc = regmap_bulk_write(regmap, reg, val, count);
>> + if (rc < 0)
>> + pr_err("failed to write %#x rc=%d\n", reg, rc);
>> +
>> + return rc;
>> +}
>
> The above two functions should just be inlined.
>
I am planning to remove these 2 APIs and use regmap_bulk_read/write
directly.
>> +
>> +static int pm8008_regulator_get_voltage(struct regulator_dev *rdev)
>> +{
>> + struct pm8008_regulator *pm8008_reg = rdev_get_drvdata(rdev);
>> + u8 vset_raw[2];
>> + int rc;
>> +
>> + rc = pm8008_read(pm8008_reg->regmap,
>> + LDO_VSET_LB_REG(pm8008_reg->base),
>> + vset_raw, 2);
>
> Can this be an __le16 mV?
>
Below is the diff after changing as per your suggestion, Please correct
me if wrong.
- u8 vset_raw[2];
+ __le16 mV;
int rc;
- rc = pm8008_read(pm8008_reg->regmap,
- LDO_VSET_LB_REG(pm8008_reg->base),
- vset_raw, 2);
+ rc = regmap_bulk_read(pm8008_reg->regmap,
+ LDO_VSET_LB_REG(pm8008_reg->base), &mV, 2);
if (rc < 0) {
dev_err(pm8008_reg->dev, "failed to read regulator
voltage rc=%d\n", rc);
return rc;
}
- return (vset_raw[1] << 8 | vset_raw[0]) * 1000;
+ return le16_to_cpu(mV) * 1000;
>> + if (rc < 0) {
>> + dev_err(pm8008_reg->dev, "failed to read regulator
>> voltage rc=%d\n", rc);
>> + return rc;
>> + }
>> +
>> + return (vset_raw[1] << 8 | vset_raw[0]) * 1000;
>
> And then 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 = 0, mv;
>> + u8 vset_raw[2];
>> +
>> + 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[0] = mv & 0xff;
>> + vset_raw[1] = (mv & 0xff00) >> 8;
>
> Make vset_raw a u16?
>
> vset = mv;
>
> And then use cpu_to_le16() below?
>
Below is the diff:
- int rc = 0, mv;
- u8 vset_raw[2];
+ int rc, mv;
+ u16 vset_raw;
[...]
- vset_raw[0] = mv & 0xff;
- vset_raw[1] = (mv & 0xff00) >> 8;
- rc = pm8008_write(pm8008_reg->regmap,
LDO_VSET_LB_REG(pm8008_reg->base),
- vset_raw, 2);
+ vset_raw = cpu_to_le16(mv);
+
+ rc = regmap_bulk_write(pm8008_reg->regmap,
+ LDO_VSET_LB_REG(pm8008_reg->base), &vset_raw,
+ sizeof(vset_raw));
>> + rc = pm8008_write(pm8008_reg->regmap,
>> LDO_VSET_LB_REG(pm8008_reg->base),
>> + vset_raw, 2);
>
> regmap_bulk_write(pm8008_reg->regmap,
> LDO_VSET_LB_REG(pm8008_reg->base),
> cpu_to_le16(vset), sizeof(vset));
>
> does it work?
>
It is working fine after modifying as above.
>> + if (rc < 0) {
>> + dev_err(pm8008_reg->dev, "failed to write voltage
>> rc=%d\n", rc);
>> + 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,
>
> Weird tabbing.
>
Will correct it.
>> + .disable = regulator_disable_regmap,
>> + .is_enabled = regulator_is_enabled_regmap,
>> + .set_voltage = pm8008_regulator_set_voltage,
>> + .get_voltage = pm8008_regulator_get_voltage,
>> + .list_voltage = regulator_list_voltage_linear,
>> + .set_voltage_time = pm8008_regulator_set_voltage_time,
>> +};
>> +
>> +static int pm8008_register_ldo(struct pm8008_regulator *pm8008_reg,
>> + const char *name)
>> +{
>> + struct regulator_config reg_config = {};
>> + struct regulator_init_data *init_data;
>> + struct device *dev = pm8008_reg->dev;
>> + struct device_node *reg_node = pm8008_reg->of_node;
>> + int rc, i;
>> + u32 base = 0;
>> + u8 reg;
>> +
>> + /* get regulator data */
>> + for (i = 0; i < PM8008_MAX_LDO; i++)
>
> Use ARRAY_SIZE()
Ok.
>
>> + if (strstr(name, reg_data[i].name))
>> + break;
>> +
>> + if (i == PM8008_MAX_LDO) {
>> + dev_err(dev, "Invalid regulator name %s\n", name);
>> + return -EINVAL;
>> + }
>> +
>> + rc = of_property_read_u32(reg_node, "reg", &base);
>> + if (rc < 0) {
>> + dev_err(dev, "%s: failed to get regulator base
>> rc=%d\n", name, rc);
>> + return rc;
>> + }
>> + pm8008_reg->base = base;
>> +
>> + /* get slew rate */
>> + rc = pm8008_read(pm8008_reg->regmap,
>> + LDO_STEPPER_CTL_REG(pm8008_reg->base), ®,
>> 1);
>> + if (rc < 0) {
>> + dev_err(dev, "%s: failed to read step rate
>> configuration rc=%d\n",
>> + name, rc);
>> + return rc;
>> + }
>> + pm8008_reg->step_rate = 38400 >> (reg & STEP_RATE_MASK);
>
> Where does 38400 come from? Is that a frequency?
>
It is the default voltage step rate. I'll add a macro
DEFAULT_VOLTAGE_STEP_RATE for this to be clear.
>> +
>> + init_data = of_get_regulator_init_data(dev, reg_node,
>> + &pm8008_reg->rdesc);
>> + if (init_data == NULL) {
>
> if (!init_data)
>
> is more kernel style.
Okay.
>
>> + dev_err(dev, "%s: failed to get regulator data\n",
>> name);
>> + return -ENODATA;
>> + }
>> +
>> + 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 = reg_node;
>> +
>> + 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_data[i].supply_name;
>> + pm8008_reg->rdesc.uV_step = VSET_STEP_UV;
>> + pm8008_reg->rdesc.min_uV = reg_data[i].min_uv;
>> + pm8008_reg->rdesc.n_voltages
>> + = ((reg_data[i].max_uv - reg_data[i].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_data[i].min_dropout_uv;
>> + of_property_read_u32(reg_node, "qcom,min-dropout-voltage",
>> + &pm8008_reg->rdesc.min_dropout_uV);
>
> Why do we allow DT to override this? Isn't it a property of the
> hardware
> that doesn't change? So the driver can hardcode the knowledge about the
> dropout.
>
The headroom values change with targets. We are adding some default
headroom values in the driver and later overwriting them with the actual
values specified in the DT.
>> +
>> + pm8008_reg->rdev = devm_regulator_register(dev,
>> &pm8008_reg->rdesc,
>
> Is this assignment ever used? Seems like it would be better to merely
>
> return PTR_ERR_OR_ZERO(devm_regulator_register(dev, ...));
>
Okay.
>> + ®_config);
>> + if (IS_ERR(pm8008_reg->rdev)) {
>> + rc = PTR_ERR(pm8008_reg->rdev);
>> + dev_err(dev, "%s: failed to register regulator
>> rc=%d\n",
>> + pm8008_reg->rdesc.name, rc);
>> + return rc;
>> + }
>> +
>> + dev_dbg(dev, "%s regulator registered\n", name);
>> +
>> + return 0;
>> +}
>> +
>> +static int pm8008_parse_regulator(struct regmap *regmap, struct
>> device *dev)
>> +{
>> + int rc = 0;
>
> Drop initialization.
>
Okay.
>> + const char *name;
>> + struct device_node *child;
>> + struct pm8008_regulator *pm8008_reg;
>> +
>> + /* parse each subnode and register regulator for regulator
>> child */
>> + for_each_available_child_of_node(dev->of_node, child) {
>> + pm8008_reg = devm_kzalloc(dev, sizeof(*pm8008_reg),
>> GFP_KERNEL);
>> +
>> + pm8008_reg->regmap = regmap;
>> + pm8008_reg->of_node = child;
>> + pm8008_reg->dev = dev;
>> +
>> + rc = of_property_read_string(child, "regulator-name",
>> &name);
>> + if (rc)
>> + continue;
>> +
>> + rc = pm8008_register_ldo(pm8008_reg, name);
>
> Can we use the of_parse_cb similar to qcom_spmi-regulator.c?
>
Are you suggesting to remove the pm8008_register_ldo API and add its
contents in probe itself and then use of_parse_cb callback like in
qcom_spmi-regulator.c?
Do we have any advantage using that here? Also I am not exactly sure
what all contents to put in that. Seems like we can put the step rate
and min-dropout-voltage configurations in there.
>> + if (rc < 0) {
>> + dev_err(dev, "failed to register regulator %s
>> rc=%d\n",
>> + name, rc);
>> + return rc;
>> + }
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int pm8008_regulator_probe(struct platform_device *pdev)
>> +{
>> + int rc = 0;
>
> Please don't initialize locals and then overwrite them before testing
> them.
>
>> + struct regmap *regmap;
>> +
>> + regmap = dev_get_regmap(pdev->dev.parent, NULL);
>> + if (!regmap) {
>> + dev_err(&pdev->dev, "parent regmap is missing\n");
>> + return -EINVAL;
>> + }
>> +
>> + rc = pm8008_parse_regulator(regmap, &pdev->dev);
>
> Just inline this code. It's basically the entire probe function so
> splitting it away to yet another function just makes it harder to read.
>
Okay.
>> + if (rc < 0) {
>> + dev_err(&pdev->dev, "failed to parse device tree
>> rc=%d\n", rc);
>> + return rc;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static const struct of_device_id pm8008_regulator_match_table[] = {
>> + { .compatible = "qcom,pm8008-regulator", },
>> + { },
>
> Nitpick: Drop comma on sentinel so nothing can come after without
> causing a compilation error.
>
Okay
>> +};
>
> Add a MODULE_DEVICE_TABLE please. Same comment applies to the mfd
> driver.
>
Okay
>> +
>> +static struct platform_driver pm8008_regulator_driver = {
>> + .driver = {
>> + .name = "qcom,pm8008-regulator",
>> + .of_match_table = pm8008_regulator_match_table,
>> + },
>> + .probe = pm8008_regulator_probe,
>
> I have no idea what's going on with this tabbing.
>
>> +};
>> +
>> +module_platform_driver(pm8008_regulator_driver);
>> +
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