Re: [PATCH 07/14] regulator: SY8106A regulator driver

["Ondřej Jirman" <megous@megous.com>]

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Hi,

thank you for the review. I've resolved most of the issues. Some more
comments below.

On 24.6.2016 05:41, Chen-Yu Tsai wrote:
> On Fri, Jun 24, 2016 at 3:20 AM,  <megous@megous.com> wrote:
>> From: Ondrej Jirman <megous@megous.com>
>>
>> SY8106A is I2C attached single output voltage regulator
>> made by Silergy.
>>
>> Signed-off-by: Ondrej Jirman <megous@megous.com>
>> ---
>>  drivers/regulator/Kconfig             |   8 +-
>>  drivers/regulator/Makefile            |   2 +-
>>  drivers/regulator/sy8106a-regulator.c | 153 ++++++++++++++++++++++++++++++++++
>>  3 files changed, 161 insertions(+), 2 deletions(-)
>>  create mode 100644 drivers/regulator/sy8106a-regulator.c
>>
>> diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
>> index 144cbf5..fc3fae2 100644
>> --- a/drivers/regulator/Kconfig
>> +++ b/drivers/regulator/Kconfig
>> @@ -860,5 +860,11 @@ config REGULATOR_WM8994
>>           This driver provides support for the voltage regulators on the
>>           WM8994 CODEC.
>>
>> -endif
>> +config REGULATOR_SY8106A
>> +       tristate "Silergy SY8106A"
>> +       depends on I2C
> 
> Maybe you should also depend on OF since the driver is going to crippled
> without any constraints set, or (OF || COMPILE_TEST) if you want some
> compile test coverage.
> 
>> +       select REGMAP_I2C
>> +       help
>> +         This driver provides support for the voltage regulator SY8106A.
>>
>> +endif
>> diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
>> index 85a1d44..f382095 100644
>> --- a/drivers/regulator/Makefile
>> +++ b/drivers/regulator/Makefile
>> @@ -110,6 +110,6 @@ obj-$(CONFIG_REGULATOR_WM831X) += wm831x-ldo.o
>>  obj-$(CONFIG_REGULATOR_WM8350) += wm8350-regulator.o
>>  obj-$(CONFIG_REGULATOR_WM8400) += wm8400-regulator.o
>>  obj-$(CONFIG_REGULATOR_WM8994) += wm8994-regulator.o
>> -
>> +obj-$(CONFIG_REGULATOR_SY8106A) += sy8106a-regulator.o
> 
> Follow the existing ordering in the Makefile.
> 
>>
>>  ccflags-$(CONFIG_REGULATOR_DEBUG) += -DDEBUG
>> diff --git a/drivers/regulator/sy8106a-regulator.c b/drivers/regulator/sy8106a-regulator.c
>> new file mode 100644
>> index 0000000..34bd69c
>> --- /dev/null
>> +++ b/drivers/regulator/sy8106a-regulator.c
>> @@ -0,0 +1,153 @@
>> +/*
>> + * sy8106a-regulator.c - Regulator device driver for SY8106A
>> + *
>> + * Copyright (C) 2016  Ondřej Jirman <megous@megous.com>
>> + *
>> + * This library is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU Library General Public
>> + * License as published by the Free Software Foundation; either
>> + * version 2 of the License, or (at your option) any later version.
>> + *
>> + * This library is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> + * Library General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU Library General Public
>> + * License along with this library; if not, write to the
>> + * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
>> + * Boston, MA  02110-1301, USA.
>> + */
>> +
>> +#include <linux/err.h>
>> +#include <linux/i2c.h>
>> +#include <linux/module.h>
>> +#include <linux/init.h>
> 
> Do you need this one?
> 
>> +#include <linux/regulator/driver.h>
>> +#include <linux/regulator/machine.h>
> 
> And this one?
> 
>> +#include <linux/regulator/of_regulator.h>
>> +#include <linux/regmap.h>
> 
> Sort alphabetically please.
> 
>> +
>> +#define SY8106A_REG_VOUT1_SEL          0x01
>> +#define SY8106A_REG_VOUT_COM           0x02
>> +#define SY8106A_REG_VOUT1_SEL_MASK     0x7f
>> +#define SY8106A_DISABLE_REG            0x01
> 
> BIT(0) would be clearer.
> 
>> +
>> +struct sy8106a {
>> +       struct regulator_dev *rdev;
>> +       struct regmap *regmap;
>> +};
>> +
>> +static const struct regmap_config sy8106a_regmap_config = {
>> +       .reg_bits = 8,
>> +       .val_bits = 8,
>> +};
>> +
>> +static int sy8106a_set_voltage_sel(struct regulator_dev *rdev, unsigned sel)
>> +{
>> +       return regmap_update_bits(rdev->regmap, rdev->desc->vsel_reg,
>> +                                 0xff, sel | 0x80);
> 
> Can you use .apply_bit / .apply_reg with regulator_set_voltage_sel_regmap?

I understand the code savings, but I'd rather avoid that, because it
would involve 2 needless readouts and rewrites of the voltage setting
register. I'd rather change this to regmap_write, so that the regulator
only receives writes over I2C, to minimize possibility of bit flip error
by minimizing the communication over the I2C bus.

>> +}
>> +
>> +static const struct regulator_ops sy8106a_ops = {
>> +       .is_enabled = regulator_is_enabled_regmap,
>> +       .set_voltage_sel = sy8106a_set_voltage_sel,
>> +       .set_voltage_time_sel = regulator_set_voltage_time_sel,
>> +       .get_voltage_sel = regulator_get_voltage_sel_regmap,
>> +       .list_voltage = regulator_list_voltage_linear,
>> +};
>> +
>> +/* Default limits measured in millivolts and milliamps */
>> +#define SY8106A_MIN_MV         680
>> +#define SY8106A_MAX_MV         1950
>> +#define SY8106A_STEP_MV                10
>> +
>> +static const struct regulator_desc sy8106a_reg = {
>> +       .name = "SY8106A",
>> +       .id = 0,
>> +       .ops = &sy8106a_ops,
>> +       .type = REGULATOR_VOLTAGE,
>> +       .n_voltages = ((SY8106A_MAX_MV - SY8106A_MIN_MV) / SY8106A_STEP_MV) + 1,
>> +       .min_uV = (SY8106A_MIN_MV * 1000),
>> +       .uV_step = (SY8106A_STEP_MV * 1000),
>> +       .vsel_reg = SY8106A_REG_VOUT1_SEL,
>> +       .vsel_mask = SY8106A_REG_VOUT1_SEL_MASK,
>> +       .enable_reg = SY8106A_REG_VOUT_COM,
>> +       .enable_mask = SY8106A_DISABLE_REG,
>> +       .disable_val = SY8106A_DISABLE_REG,
>> +       .enable_is_inverted = 1,
>> +       .owner = THIS_MODULE,
>> +};
>> +
>> +/*
>> + * I2C driver interface functions
>> + */
>> +static int sy8106a_i2c_probe(struct i2c_client *i2c,
>> +                           const struct i2c_device_id *id)
>> +{
>> +       struct sy8106a *chip;
>> +       struct device *dev = &i2c->dev;
>> +       struct regulator_dev *rdev = NULL;
>> +       struct regulator_config config = { };
>> +       unsigned int selector;
>> +       int error;
>> +
>> +       chip = devm_kzalloc(&i2c->dev, sizeof(struct sy8106a), GFP_KERNEL);
>> +       if (!chip)
>> +               return -ENOMEM;
>> +
>> +       chip->regmap = devm_regmap_init_i2c(i2c, &sy8106a_regmap_config);
>> +       if (IS_ERR(chip->regmap)) {
>> +               error = PTR_ERR(chip->regmap);
>> +               dev_err(&i2c->dev, "Failed to allocate register map: %d\n",
>> +                       error);
>> +               return error;
>> +       }
>> +
>> +       config.dev = &i2c->dev;
>> +       config.init_data = of_get_regulator_init_data(dev, dev->of_node, &sy8106a_reg);
> 
> Check for possible failures?
> 
>> +       config.driver_data = chip;
>> +       config.regmap = chip->regmap;
>> +       config.of_node = dev->of_node;
>> +
>> +       /* Probe regulator */
>> +       error = regmap_read(chip->regmap, SY8106A_REG_VOUT1_SEL, &selector);
>> +       dev_info(&i2c->dev, "SY8106A voltage at boot: %u mV\n", SY8106A_MIN_MV + SY8106A_STEP_MV * (selector & SY8106A_REG_VOUT1_SEL_MASK));
>> +       if (error) {
>> +               dev_err(&i2c->dev, "Failed to read voltage at probe time: %d\n", error);
>> +               return error;
>> +       }
>> +
>> +       rdev = devm_regulator_register(&i2c->dev, &sy8106a_reg, &config);
>> +       if (IS_ERR(rdev)) {
>> +               dev_err(&i2c->dev, "Failed to register SY8106A regulator\n");
>> +               return PTR_ERR(rdev);
>> +       }
>> +
>> +       chip->rdev = rdev;
>> +
>> +       i2c_set_clientdata(i2c, chip);
>> +
>> +       return 0;
>> +}
>> +
>> +static const struct i2c_device_id sy8106a_i2c_id[] = {
>> +       {"sy8106a", 0},
>> +       {},
>> +};
>> +
> 
> Extra line.
> 
>> +MODULE_DEVICE_TABLE(i2c, sy8106a_i2c_id);
> 
> IMHO probing explicitly through DT (of_device_id) would be better.

I checked out a few recently added i2c regulator drivers, and this is
the way they're written. I'd rather not differ, especially since I'm a
beginner with this thing, atm. Also, I'm not sure what chanhge in
particular you're suggesting.

thanks,
  Ondrej

> 
> Regards
> ChenYu
> 
>> +
>> +static struct i2c_driver sy8106a_regulator_driver = {
>> +       .driver = {
>> +               .name = "sy8106a",
>> +       },
>> +       .probe = sy8106a_i2c_probe,
>> +       .id_table = sy8106a_i2c_id,
>> +};
>> +
>> +module_i2c_driver(sy8106a_regulator_driver);
>> +
>> +MODULE_AUTHOR("Ondřej Jirman <megous@megous.com>");
>> +MODULE_DESCRIPTION("Regulator device driver for Silergy SY8106A");
>> +MODULE_LICENSE("GPL v2");
>> --
>> 2.9.0
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel


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