[02/10] regulator: add support for SY8106A regulator

Message ID 20170723102749.17323-3-icenowy@aosc.io
State New
Headers show

Commit Message

Icenowy Zheng July 23, 2017, 10:27 a.m.
From: Ondrej Jirman <megous@megous.com>

SY8106A is an I2C attached single output regulator made by Silergy Corp,
which is used on several Allwinner H3/H5 SBCs to control the power
supply of the ARM cores.

Add a driver for it.

Signed-off-by: Ondrej Jirman <megous@megous.com>
[Icenowy: Change commit message]
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
---
 drivers/regulator/Kconfig             |   8 +-
 drivers/regulator/Makefile            |   2 +-
 drivers/regulator/sy8106a-regulator.c | 163 ++++++++++++++++++++++++++++++++++
 3 files changed, 171 insertions(+), 2 deletions(-)
 create mode 100644 drivers/regulator/sy8106a-regulator.c

Comments

Chen-Yu Tsai July 24, 2017, 3:03 a.m. | #1
On Sun, Jul 23, 2017 at 6:27 PM, Icenowy Zheng <icenowy@aosc.io> wrote:
> From: Ondrej Jirman <megous@megous.com>
>
> SY8106A is an I2C attached single output regulator made by Silergy Corp,
> which is used on several Allwinner H3/H5 SBCs to control the power
> supply of the ARM cores.
>
> Add a driver for it.
>
> Signed-off-by: Ondrej Jirman <megous@megous.com>
> [Icenowy: Change commit message]
> Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
> ---
>  drivers/regulator/Kconfig             |   8 +-
>  drivers/regulator/Makefile            |   2 +-
>  drivers/regulator/sy8106a-regulator.c | 163 ++++++++++++++++++++++++++++++++++
>  3 files changed, 171 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/regulator/sy8106a-regulator.c
>
> diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
> index 99b9362331b5..1efa73e18d07 100644
> --- a/drivers/regulator/Kconfig
> +++ b/drivers/regulator/Kconfig
> @@ -764,6 +764,13 @@ config REGULATOR_STW481X_VMMC
>           This driver supports the internal VMMC regulator in the STw481x
>           PMIC chips.
>
> +config REGULATOR_SY8106A
> +       tristate "Silergy SY8106A regulator"
> +       depends on I2C && (OF || COMPILE_TEST)
> +       select REGMAP_I2C
> +       help
> +         This driver supports SY8106A single output regulator.
> +
>  config REGULATOR_TPS51632
>         tristate "TI TPS51632 Power Regulator"
>         depends on I2C
> @@ -938,4 +945,3 @@ config REGULATOR_WM8994
>           WM8994 CODEC.
>
>  endif
> -
> diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
> index 95b1e86ae692..f5120252f86a 100644
> --- a/drivers/regulator/Makefile
> +++ b/drivers/regulator/Makefile
> @@ -95,6 +95,7 @@ obj-$(CONFIG_REGULATOR_S2MPS11) += s2mps11.o
>  obj-$(CONFIG_REGULATOR_S5M8767) += s5m8767.o
>  obj-$(CONFIG_REGULATOR_SKY81452) += sky81452-regulator.o
>  obj-$(CONFIG_REGULATOR_STW481X_VMMC) += stw481x-vmmc.o
> +obj-$(CONFIG_REGULATOR_SY8106A) += sy8106a-regulator.o
>  obj-$(CONFIG_REGULATOR_TI_ABB) += ti-abb-regulator.o
>  obj-$(CONFIG_REGULATOR_TPS6105X) += tps6105x-regulator.o
>  obj-$(CONFIG_REGULATOR_TPS62360) += tps62360-regulator.o
> @@ -120,5 +121,4 @@ obj-$(CONFIG_REGULATOR_WM8350) += wm8350-regulator.o
>  obj-$(CONFIG_REGULATOR_WM8400) += wm8400-regulator.o
>  obj-$(CONFIG_REGULATOR_WM8994) += wm8994-regulator.o
>
> -
>  ccflags-$(CONFIG_REGULATOR_DEBUG) += -DDEBUG
> diff --git a/drivers/regulator/sy8106a-regulator.c b/drivers/regulator/sy8106a-regulator.c
> new file mode 100644
> index 000000000000..1df889f68b3d
> --- /dev/null
> +++ b/drivers/regulator/sy8106a-regulator.c
> @@ -0,0 +1,163 @@
> +/*
> + * sy8106a-regulator.c - Regulator device driver for SY8106A
> + *
> + * Copyright (C) 2016 Ondřej Jirman <megous@megous.com>
> + *
> + * This program 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 program 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.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/driver.h>
> +#include <linux/regulator/of_regulator.h>
> +
> +#define SY8106A_REG_VOUT1_SEL          0x01
> +#define SY8106A_REG_VOUT_COM           0x02
> +#define SY8106A_REG_VOUT1_SEL_MASK     0x7f
> +#define SY8106A_DISABLE_REG            BIT(0)
> +#define SY8106A_GO_BIT                 BIT(7)
> +
> +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 int sel)
> +{
> +       /* We use our set_voltage_sel in order to avoid unnecessary I2C
> +        * chatter, because the regulator_get_voltage_sel_regmap using
> +        * apply_bit would perform 4 unnecessary transfers instead of one,
> +        * increasing the chance of error.
> +        */
> +       return regmap_write(rdev->regmap, rdev->desc->vsel_reg,
> +                           sel | SY8106A_GO_BIT);

There should also be an explanation of what the "go bit" does.
In this case it enables control of the voltage over I2C.

> +}
> +
> +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,

No enable/disable ops?

> +};
> +
> +/* 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,

As the regulator core helpers currently are, there is no way to disable
this regulator. regulator_disable_regmap looks like:

        if (rdev->desc->enable_is_inverted) {
                val = rdev->desc->enable_val;
                if (!val)
                        val = rdev->desc->enable_mask;
        } else {
                val = rdev->desc->disable_val;
        }

        return regmap_update_bits(rdev->regmap, rdev->desc->enable_reg,
                                  rdev->desc->enable_mask, val);

Note the fallback to enable_mask if enable_val is not set. The enable
helper has a similar structure. This regulator uses an enable value
of 0, and disable value of 1, it is impossible to get it right. As
it is now, it doesn't really make sense to me.

The code was introduced in ca5d1b3524b4 ("regulator: helpers: Modify
helpers enabling multi-bit control"). I wonder if it was an unintended
consequence of the change? (original author CC-ed)

> +       .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.regmap = chip->regmap;
> +       config.driver_data = chip;
> +
> +       config.of_node = dev->of_node;
> +       config.init_data = of_get_regulator_init_data(dev, dev->of_node,
> +                                                     &sy8106a_reg);
> +
> +       if (!config.init_data)
> +               return -ENOMEM;
> +
> +       /* Probe regulator */
> +       error = regmap_read(chip->regmap, SY8106A_REG_VOUT1_SEL, &selector);
> +       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)) {
> +               error = PTR_ERR(rdev);
> +               dev_err(&i2c->dev, "Failed to register SY8106A regulator: %d\n", error);
> +               return error;
> +       }
> +
> +       chip->rdev = rdev;
> +
> +       i2c_set_clientdata(i2c, chip);
> +
> +       return 0;
> +}
> +
> +static const struct of_device_id sy8106a_i2c_of_match[] = {
> +       { .compatible = "silergy,sy8106a" },
> +       { },
> +};
> +MODULE_DEVICE_TABLE(of, sy8106a_i2c_of_match);
> +
> +static const struct i2c_device_id sy8106a_i2c_id[] = {
> +       { "sy8106a", 0 },
> +       { },
> +};
> +MODULE_DEVICE_TABLE(i2c, sy8106a_i2c_id);
> +
> +static struct i2c_driver sy8106a_regulator_driver = {
> +       .driver = {
> +               .name = "sy8106a",
> +               .of_match_table = of_match_ptr(sy8106a_i2c_of_match),
> +       },
> +       .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");

This should be "GPL", to match what the license at the very top says.

Regards
ChenYu

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Icenowy Zheng July 24, 2017, 3:18 a.m. | #2
在 2017-07-24 11:03,Chen-Yu Tsai 写道:
> On Sun, Jul 23, 2017 at 6:27 PM, Icenowy Zheng <icenowy@aosc.io> wrote:
>> From: Ondrej Jirman <megous@megous.com>
>> 
>> SY8106A is an I2C attached single output regulator made by Silergy 
>> Corp,
>> which is used on several Allwinner H3/H5 SBCs to control the power
>> supply of the ARM cores.
>> 
>> Add a driver for it.
>> 
>> Signed-off-by: Ondrej Jirman <megous@megous.com>
>> [Icenowy: Change commit message]
>> Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
>> ---
>>  drivers/regulator/Kconfig             |   8 +-
>>  drivers/regulator/Makefile            |   2 +-
>>  drivers/regulator/sy8106a-regulator.c | 163 
>> ++++++++++++++++++++++++++++++++++
>>  3 files changed, 171 insertions(+), 2 deletions(-)
>>  create mode 100644 drivers/regulator/sy8106a-regulator.c
>> 
>> diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
>> index 99b9362331b5..1efa73e18d07 100644
>> --- a/drivers/regulator/Kconfig
>> +++ b/drivers/regulator/Kconfig
>> @@ -764,6 +764,13 @@ config REGULATOR_STW481X_VMMC
>>           This driver supports the internal VMMC regulator in the 
>> STw481x
>>           PMIC chips.
>> 
>> +config REGULATOR_SY8106A
>> +       tristate "Silergy SY8106A regulator"
>> +       depends on I2C && (OF || COMPILE_TEST)
>> +       select REGMAP_I2C
>> +       help
>> +         This driver supports SY8106A single output regulator.
>> +
>>  config REGULATOR_TPS51632
>>         tristate "TI TPS51632 Power Regulator"
>>         depends on I2C
>> @@ -938,4 +945,3 @@ config REGULATOR_WM8994
>>           WM8994 CODEC.
>> 
>>  endif
>> -
>> diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
>> index 95b1e86ae692..f5120252f86a 100644
>> --- a/drivers/regulator/Makefile
>> +++ b/drivers/regulator/Makefile
>> @@ -95,6 +95,7 @@ obj-$(CONFIG_REGULATOR_S2MPS11) += s2mps11.o
>>  obj-$(CONFIG_REGULATOR_S5M8767) += s5m8767.o
>>  obj-$(CONFIG_REGULATOR_SKY81452) += sky81452-regulator.o
>>  obj-$(CONFIG_REGULATOR_STW481X_VMMC) += stw481x-vmmc.o
>> +obj-$(CONFIG_REGULATOR_SY8106A) += sy8106a-regulator.o
>>  obj-$(CONFIG_REGULATOR_TI_ABB) += ti-abb-regulator.o
>>  obj-$(CONFIG_REGULATOR_TPS6105X) += tps6105x-regulator.o
>>  obj-$(CONFIG_REGULATOR_TPS62360) += tps62360-regulator.o
>> @@ -120,5 +121,4 @@ obj-$(CONFIG_REGULATOR_WM8350) += 
>> wm8350-regulator.o
>>  obj-$(CONFIG_REGULATOR_WM8400) += wm8400-regulator.o
>>  obj-$(CONFIG_REGULATOR_WM8994) += wm8994-regulator.o
>> 
>> -
>>  ccflags-$(CONFIG_REGULATOR_DEBUG) += -DDEBUG
>> diff --git a/drivers/regulator/sy8106a-regulator.c 
>> b/drivers/regulator/sy8106a-regulator.c
>> new file mode 100644
>> index 000000000000..1df889f68b3d
>> --- /dev/null
>> +++ b/drivers/regulator/sy8106a-regulator.c
>> @@ -0,0 +1,163 @@
>> +/*
>> + * sy8106a-regulator.c - Regulator device driver for SY8106A
>> + *
>> + * Copyright (C) 2016 Ondřej Jirman <megous@megous.com>
>> + *
>> + * This program 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 program 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.
>> + */
>> +
>> +#include <linux/err.h>
>> +#include <linux/i2c.h>
>> +#include <linux/module.h>
>> +#include <linux/regmap.h>
>> +#include <linux/regulator/driver.h>
>> +#include <linux/regulator/of_regulator.h>
>> +
>> +#define SY8106A_REG_VOUT1_SEL          0x01
>> +#define SY8106A_REG_VOUT_COM           0x02
>> +#define SY8106A_REG_VOUT1_SEL_MASK     0x7f
>> +#define SY8106A_DISABLE_REG            BIT(0)
>> +#define SY8106A_GO_BIT                 BIT(7)
>> +
>> +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 int sel)
>> +{
>> +       /* We use our set_voltage_sel in order to avoid unnecessary 
>> I2C
>> +        * chatter, because the regulator_get_voltage_sel_regmap using
>> +        * apply_bit would perform 4 unnecessary transfers instead of 
>> one,
>> +        * increasing the chance of error.
>> +        */
>> +       return regmap_write(rdev->regmap, rdev->desc->vsel_reg,
>> +                           sel | SY8106A_GO_BIT);
> 
> There should also be an explanation of what the "go bit" does.
> In this case it enables control of the voltage over I2C.
> 
>> +}
>> +
>> +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,
> 
> No enable/disable ops?
> 
>> +};
>> +
>> +/* 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,
> 
> As the regulator core helpers currently are, there is no way to disable
> this regulator. regulator_disable_regmap looks like:

By reading the current code, I think removing the disable_val variable 
will
just make it work -- when enabling, the enable_reg will be set to 
disable_val
(as enable_is_inverted is 1), and disable_val is defaultly 0; when 
disabling,
the enable_reg will be set to enable_mask (fallbacked from enable_val, 
which
is also the default value 0), and the regulator successfully get 
disabled.

> 
>         if (rdev->desc->enable_is_inverted) {
>                 val = rdev->desc->enable_val;
>                 if (!val)
>                         val = rdev->desc->enable_mask;
>         } else {
>                 val = rdev->desc->disable_val;
>         }
> 
>         return regmap_update_bits(rdev->regmap, rdev->desc->enable_reg,
>                                   rdev->desc->enable_mask, val);
> 
> Note the fallback to enable_mask if enable_val is not set. The enable
> helper has a similar structure. This regulator uses an enable value
> of 0, and disable value of 1, it is impossible to get it right. As
> it is now, it doesn't really make sense to me.
> 
> The code was introduced in ca5d1b3524b4 ("regulator: helpers: Modify
> helpers enabling multi-bit control"). I wonder if it was an unintended
> consequence of the change? (original author CC-ed)
> 
>> +       .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.regmap = chip->regmap;
>> +       config.driver_data = chip;
>> +
>> +       config.of_node = dev->of_node;
>> +       config.init_data = of_get_regulator_init_data(dev, 
>> dev->of_node,
>> +                                                     &sy8106a_reg);
>> +
>> +       if (!config.init_data)
>> +               return -ENOMEM;
>> +
>> +       /* Probe regulator */
>> +       error = regmap_read(chip->regmap, SY8106A_REG_VOUT1_SEL, 
>> &selector);
>> +       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)) {
>> +               error = PTR_ERR(rdev);
>> +               dev_err(&i2c->dev, "Failed to register SY8106A 
>> regulator: %d\n", error);
>> +               return error;
>> +       }
>> +
>> +       chip->rdev = rdev;
>> +
>> +       i2c_set_clientdata(i2c, chip);
>> +
>> +       return 0;
>> +}
>> +
>> +static const struct of_device_id sy8106a_i2c_of_match[] = {
>> +       { .compatible = "silergy,sy8106a" },
>> +       { },
>> +};
>> +MODULE_DEVICE_TABLE(of, sy8106a_i2c_of_match);
>> +
>> +static const struct i2c_device_id sy8106a_i2c_id[] = {
>> +       { "sy8106a", 0 },
>> +       { },
>> +};
>> +MODULE_DEVICE_TABLE(i2c, sy8106a_i2c_id);
>> +
>> +static struct i2c_driver sy8106a_regulator_driver = {
>> +       .driver = {
>> +               .name = "sy8106a",
>> +               .of_match_table = of_match_ptr(sy8106a_i2c_of_match),
>> +       },
>> +       .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");
> 
> This should be "GPL", to match what the license at the very top says.
> 
> Regards
> ChenYu
> 
>> --
>> 2.13.0
>> 
>> --
>> You received this message because you are subscribed to the Google 
>> Groups "linux-sunxi" group.
>> To unsubscribe from this group and stop receiving emails from it, send 
>> an email to linux-sunxi+unsubscribe@googlegroups.com.
>> For more options, visit https://groups.google.com/d/optout.
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Chen-Yu Tsai July 24, 2017, 3:33 a.m. | #3
On Mon, Jul 24, 2017 at 11:18 AM,  <icenowy@aosc.io> wrote:
> 在 2017-07-24 11:03,Chen-Yu Tsai 写道:
>>
>> On Sun, Jul 23, 2017 at 6:27 PM, Icenowy Zheng <icenowy@aosc.io> wrote:
>>>
>>> From: Ondrej Jirman <megous@megous.com>
>>>
>>> SY8106A is an I2C attached single output regulator made by Silergy Corp,
>>> which is used on several Allwinner H3/H5 SBCs to control the power
>>> supply of the ARM cores.
>>>
>>> Add a driver for it.
>>>
>>> Signed-off-by: Ondrej Jirman <megous@megous.com>
>>> [Icenowy: Change commit message]
>>> Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
>>> ---
>>>  drivers/regulator/Kconfig             |   8 +-
>>>  drivers/regulator/Makefile            |   2 +-
>>>  drivers/regulator/sy8106a-regulator.c | 163
>>> ++++++++++++++++++++++++++++++++++
>>>  3 files changed, 171 insertions(+), 2 deletions(-)
>>>  create mode 100644 drivers/regulator/sy8106a-regulator.c
>>>
>>> diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
>>> index 99b9362331b5..1efa73e18d07 100644
>>> --- a/drivers/regulator/Kconfig
>>> +++ b/drivers/regulator/Kconfig
>>> @@ -764,6 +764,13 @@ config REGULATOR_STW481X_VMMC
>>>           This driver supports the internal VMMC regulator in the STw481x
>>>           PMIC chips.
>>>
>>> +config REGULATOR_SY8106A
>>> +       tristate "Silergy SY8106A regulator"
>>> +       depends on I2C && (OF || COMPILE_TEST)
>>> +       select REGMAP_I2C
>>> +       help
>>> +         This driver supports SY8106A single output regulator.
>>> +
>>>  config REGULATOR_TPS51632
>>>         tristate "TI TPS51632 Power Regulator"
>>>         depends on I2C
>>> @@ -938,4 +945,3 @@ config REGULATOR_WM8994
>>>           WM8994 CODEC.
>>>
>>>  endif
>>> -
>>> diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
>>> index 95b1e86ae692..f5120252f86a 100644
>>> --- a/drivers/regulator/Makefile
>>> +++ b/drivers/regulator/Makefile
>>> @@ -95,6 +95,7 @@ obj-$(CONFIG_REGULATOR_S2MPS11) += s2mps11.o
>>>  obj-$(CONFIG_REGULATOR_S5M8767) += s5m8767.o
>>>  obj-$(CONFIG_REGULATOR_SKY81452) += sky81452-regulator.o
>>>  obj-$(CONFIG_REGULATOR_STW481X_VMMC) += stw481x-vmmc.o
>>> +obj-$(CONFIG_REGULATOR_SY8106A) += sy8106a-regulator.o
>>>  obj-$(CONFIG_REGULATOR_TI_ABB) += ti-abb-regulator.o
>>>  obj-$(CONFIG_REGULATOR_TPS6105X) += tps6105x-regulator.o
>>>  obj-$(CONFIG_REGULATOR_TPS62360) += tps62360-regulator.o
>>> @@ -120,5 +121,4 @@ obj-$(CONFIG_REGULATOR_WM8350) += wm8350-regulator.o
>>>  obj-$(CONFIG_REGULATOR_WM8400) += wm8400-regulator.o
>>>  obj-$(CONFIG_REGULATOR_WM8994) += wm8994-regulator.o
>>>
>>> -
>>>  ccflags-$(CONFIG_REGULATOR_DEBUG) += -DDEBUG
>>> diff --git a/drivers/regulator/sy8106a-regulator.c
>>> b/drivers/regulator/sy8106a-regulator.c
>>> new file mode 100644
>>> index 000000000000..1df889f68b3d
>>> --- /dev/null
>>> +++ b/drivers/regulator/sy8106a-regulator.c
>>> @@ -0,0 +1,163 @@
>>> +/*
>>> + * sy8106a-regulator.c - Regulator device driver for SY8106A
>>> + *
>>> + * Copyright (C) 2016 Ondřej Jirman <megous@megous.com>
>>> + *
>>> + * This program 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 program 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.
>>> + */
>>> +
>>> +#include <linux/err.h>
>>> +#include <linux/i2c.h>
>>> +#include <linux/module.h>
>>> +#include <linux/regmap.h>
>>> +#include <linux/regulator/driver.h>
>>> +#include <linux/regulator/of_regulator.h>
>>> +
>>> +#define SY8106A_REG_VOUT1_SEL          0x01
>>> +#define SY8106A_REG_VOUT_COM           0x02
>>> +#define SY8106A_REG_VOUT1_SEL_MASK     0x7f
>>> +#define SY8106A_DISABLE_REG            BIT(0)
>>> +#define SY8106A_GO_BIT                 BIT(7)
>>> +
>>> +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
>>> int sel)
>>> +{
>>> +       /* We use our set_voltage_sel in order to avoid unnecessary I2C
>>> +        * chatter, because the regulator_get_voltage_sel_regmap using
>>> +        * apply_bit would perform 4 unnecessary transfers instead of
>>> one,
>>> +        * increasing the chance of error.
>>> +        */
>>> +       return regmap_write(rdev->regmap, rdev->desc->vsel_reg,
>>> +                           sel | SY8106A_GO_BIT);
>>
>>
>> There should also be an explanation of what the "go bit" does.
>> In this case it enables control of the voltage over I2C.
>>
>>> +}
>>> +
>>> +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,
>>
>>
>> No enable/disable ops?
>>
>>> +};
>>> +
>>> +/* 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,
>>
>>
>> As the regulator core helpers currently are, there is no way to disable
>> this regulator. regulator_disable_regmap looks like:
>
>
> By reading the current code, I think removing the disable_val variable will
> just make it work -- when enabling, the enable_reg will be set to disable_val
> (as enable_is_inverted is 1), and disable_val is defaultly 0; when disabling,
> the enable_reg will be set to enable_mask (fallbacked from enable_val, which
> is also the default value 0), and the regulator successfully get disabled.

(Gmail is wrapping the lines :( )

enable_mask is set to SY8106A_DISABLE_REG, which equals disable_val here,
which is not 0. This is correct, as it is the bit mask passed to
regmap_update_bits. So no, it does not work.

It seems quite a lot of drivers depend on this fallback behavior though.

ChenYu

>
>>
>>         if (rdev->desc->enable_is_inverted) {
>>                 val = rdev->desc->enable_val;
>>                 if (!val)
>>                         val = rdev->desc->enable_mask;
>>         } else {
>>                 val = rdev->desc->disable_val;
>>         }
>>
>>         return regmap_update_bits(rdev->regmap, rdev->desc->enable_reg,
>>                                   rdev->desc->enable_mask, val);
>>
>> Note the fallback to enable_mask if enable_val is not set. The enable
>> helper has a similar structure. This regulator uses an enable value
>> of 0, and disable value of 1, it is impossible to get it right. As
>> it is now, it doesn't really make sense to me.
>>
>> The code was introduced in ca5d1b3524b4 ("regulator: helpers: Modify
>> helpers enabling multi-bit control"). I wonder if it was an unintended
>> consequence of the change? (original author CC-ed)
>>
>>> +       .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.regmap = chip->regmap;
>>> +       config.driver_data = chip;
>>> +
>>> +       config.of_node = dev->of_node;
>>> +       config.init_data = of_get_regulator_init_data(dev, dev->of_node,
>>> +                                                     &sy8106a_reg);
>>> +
>>> +       if (!config.init_data)
>>> +               return -ENOMEM;
>>> +
>>> +       /* Probe regulator */
>>> +       error = regmap_read(chip->regmap, SY8106A_REG_VOUT1_SEL,
>>> &selector);
>>> +       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)) {
>>> +               error = PTR_ERR(rdev);
>>> +               dev_err(&i2c->dev, "Failed to register SY8106A regulator:
>>> %d\n", error);
>>> +               return error;
>>> +       }
>>> +
>>> +       chip->rdev = rdev;
>>> +
>>> +       i2c_set_clientdata(i2c, chip);
>>> +
>>> +       return 0;
>>> +}
>>> +
>>> +static const struct of_device_id sy8106a_i2c_of_match[] = {
>>> +       { .compatible = "silergy,sy8106a" },
>>> +       { },
>>> +};
>>> +MODULE_DEVICE_TABLE(of, sy8106a_i2c_of_match);
>>> +
>>> +static const struct i2c_device_id sy8106a_i2c_id[] = {
>>> +       { "sy8106a", 0 },
>>> +       { },
>>> +};
>>> +MODULE_DEVICE_TABLE(i2c, sy8106a_i2c_id);
>>> +
>>> +static struct i2c_driver sy8106a_regulator_driver = {
>>> +       .driver = {
>>> +               .name = "sy8106a",
>>> +               .of_match_table = of_match_ptr(sy8106a_i2c_of_match),
>>> +       },
>>> +       .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");
>>
>>
>> This should be "GPL", to match what the license at the very top says.
>>
>> Regards
>> ChenYu
>>
>>> --
>>> 2.13.0
>>>
>>> --
>>> You received this message because you are subscribed to the Google Groups
>>> "linux-sunxi" group.
>>> To unsubscribe from this group and stop receiving emails from it, send an
>>> email to linux-sunxi+unsubscribe@googlegroups.com.
>>> For more options, visit https://groups.google.com/d/optout.
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
>
> --
> You received this message because you are subscribed to the Google Groups
> "linux-sunxi" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to linux-sunxi+unsubscribe@googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.
Icenowy Zheng July 24, 2017, 3:38 a.m. | #4
在 2017-07-24 11:33,Chen-Yu Tsai 写道:
> On Mon, Jul 24, 2017 at 11:18 AM,  <icenowy@aosc.io> wrote:
>> 在 2017-07-24 11:03,Chen-Yu Tsai 写道:
>>> 
>>> On Sun, Jul 23, 2017 at 6:27 PM, Icenowy Zheng <icenowy@aosc.io> 
>>> wrote:
>>>> 
>>>> From: Ondrej Jirman <megous@megous.com>
>>>> 
>>>> SY8106A is an I2C attached single output regulator made by Silergy 
>>>> Corp,
>>>> which is used on several Allwinner H3/H5 SBCs to control the power
>>>> supply of the ARM cores.
>>>> 
>>>> Add a driver for it.
>>>> 
>>>> Signed-off-by: Ondrej Jirman <megous@megous.com>
>>>> [Icenowy: Change commit message]
>>>> Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
>>>> ---
>>>>  drivers/regulator/Kconfig             |   8 +-
>>>>  drivers/regulator/Makefile            |   2 +-
>>>>  drivers/regulator/sy8106a-regulator.c | 163
>>>> ++++++++++++++++++++++++++++++++++
>>>>  3 files changed, 171 insertions(+), 2 deletions(-)
>>>>  create mode 100644 drivers/regulator/sy8106a-regulator.c
>>>> 
>>>> diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
>>>> index 99b9362331b5..1efa73e18d07 100644
>>>> --- a/drivers/regulator/Kconfig
>>>> +++ b/drivers/regulator/Kconfig
>>>> @@ -764,6 +764,13 @@ config REGULATOR_STW481X_VMMC
>>>>           This driver supports the internal VMMC regulator in the 
>>>> STw481x
>>>>           PMIC chips.
>>>> 
>>>> +config REGULATOR_SY8106A
>>>> +       tristate "Silergy SY8106A regulator"
>>>> +       depends on I2C && (OF || COMPILE_TEST)
>>>> +       select REGMAP_I2C
>>>> +       help
>>>> +         This driver supports SY8106A single output regulator.
>>>> +
>>>>  config REGULATOR_TPS51632
>>>>         tristate "TI TPS51632 Power Regulator"
>>>>         depends on I2C
>>>> @@ -938,4 +945,3 @@ config REGULATOR_WM8994
>>>>           WM8994 CODEC.
>>>> 
>>>>  endif
>>>> -
>>>> diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
>>>> index 95b1e86ae692..f5120252f86a 100644
>>>> --- a/drivers/regulator/Makefile
>>>> +++ b/drivers/regulator/Makefile
>>>> @@ -95,6 +95,7 @@ obj-$(CONFIG_REGULATOR_S2MPS11) += s2mps11.o
>>>>  obj-$(CONFIG_REGULATOR_S5M8767) += s5m8767.o
>>>>  obj-$(CONFIG_REGULATOR_SKY81452) += sky81452-regulator.o
>>>>  obj-$(CONFIG_REGULATOR_STW481X_VMMC) += stw481x-vmmc.o
>>>> +obj-$(CONFIG_REGULATOR_SY8106A) += sy8106a-regulator.o
>>>>  obj-$(CONFIG_REGULATOR_TI_ABB) += ti-abb-regulator.o
>>>>  obj-$(CONFIG_REGULATOR_TPS6105X) += tps6105x-regulator.o
>>>>  obj-$(CONFIG_REGULATOR_TPS62360) += tps62360-regulator.o
>>>> @@ -120,5 +121,4 @@ obj-$(CONFIG_REGULATOR_WM8350) += 
>>>> wm8350-regulator.o
>>>>  obj-$(CONFIG_REGULATOR_WM8400) += wm8400-regulator.o
>>>>  obj-$(CONFIG_REGULATOR_WM8994) += wm8994-regulator.o
>>>> 
>>>> -
>>>>  ccflags-$(CONFIG_REGULATOR_DEBUG) += -DDEBUG
>>>> diff --git a/drivers/regulator/sy8106a-regulator.c
>>>> b/drivers/regulator/sy8106a-regulator.c
>>>> new file mode 100644
>>>> index 000000000000..1df889f68b3d
>>>> --- /dev/null
>>>> +++ b/drivers/regulator/sy8106a-regulator.c
>>>> @@ -0,0 +1,163 @@
>>>> +/*
>>>> + * sy8106a-regulator.c - Regulator device driver for SY8106A
>>>> + *
>>>> + * Copyright (C) 2016 Ondřej Jirman <megous@megous.com>
>>>> + *
>>>> + * This program 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 program 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.
>>>> + */
>>>> +
>>>> +#include <linux/err.h>
>>>> +#include <linux/i2c.h>
>>>> +#include <linux/module.h>
>>>> +#include <linux/regmap.h>
>>>> +#include <linux/regulator/driver.h>
>>>> +#include <linux/regulator/of_regulator.h>
>>>> +
>>>> +#define SY8106A_REG_VOUT1_SEL          0x01
>>>> +#define SY8106A_REG_VOUT_COM           0x02
>>>> +#define SY8106A_REG_VOUT1_SEL_MASK     0x7f
>>>> +#define SY8106A_DISABLE_REG            BIT(0)
>>>> +#define SY8106A_GO_BIT                 BIT(7)
>>>> +
>>>> +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
>>>> int sel)
>>>> +{
>>>> +       /* We use our set_voltage_sel in order to avoid unnecessary 
>>>> I2C
>>>> +        * chatter, because the regulator_get_voltage_sel_regmap 
>>>> using
>>>> +        * apply_bit would perform 4 unnecessary transfers instead 
>>>> of
>>>> one,
>>>> +        * increasing the chance of error.
>>>> +        */
>>>> +       return regmap_write(rdev->regmap, rdev->desc->vsel_reg,
>>>> +                           sel | SY8106A_GO_BIT);
>>> 
>>> 
>>> There should also be an explanation of what the "go bit" does.
>>> In this case it enables control of the voltage over I2C.
>>> 
>>>> +}
>>>> +
>>>> +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,
>>> 
>>> 
>>> No enable/disable ops?
>>> 
>>>> +};
>>>> +
>>>> +/* 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,
>>> 
>>> 
>>> As the regulator core helpers currently are, there is no way to 
>>> disable
>>> this regulator. regulator_disable_regmap looks like:
>> 
>> 
>> By reading the current code, I think removing the disable_val variable 
>> will
>> just make it work -- when enabling, the enable_reg will be set to 
>> disable_val
>> (as enable_is_inverted is 1), and disable_val is defaultly 0; when 
>> disabling,
>> the enable_reg will be set to enable_mask (fallbacked from enable_val, 
>> which
>> is also the default value 0), and the regulator successfully get 
>> disabled.
> 
> (Gmail is wrapping the lines :( )
> 
> enable_mask is set to SY8106A_DISABLE_REG, which equals disable_val 
> here,
> which is not 0. This is correct, as it is the bit mask passed to
> regmap_update_bits. So no, it does not work.

 From my personal understanding of the code, the behavior of 
enable_is_inverted
is that switch the roles of enable_val and disable_val, so if
enable_is_inverted is set, the regulator_disable_regmap function will 
write
enable_val (if it's 0, fallback to enable_mask) to the register, and
regulator_enable_regmap will write disable_val.

Maybe this design is used to ensure enable_val (then fallback to 
enable_mask)
is not 0.

> 
> It seems quite a lot of drivers depend on this fallback behavior 
> though.
> 
> ChenYu
> 
>> 
>>> 
>>>         if (rdev->desc->enable_is_inverted) {
>>>                 val = rdev->desc->enable_val;
>>>                 if (!val)
>>>                         val = rdev->desc->enable_mask;
>>>         } else {
>>>                 val = rdev->desc->disable_val;
>>>         }
>>> 
>>>         return regmap_update_bits(rdev->regmap, 
>>> rdev->desc->enable_reg,
>>>                                   rdev->desc->enable_mask, val);
>>> 
>>> Note the fallback to enable_mask if enable_val is not set. The enable
>>> helper has a similar structure. This regulator uses an enable value
>>> of 0, and disable value of 1, it is impossible to get it right. As
>>> it is now, it doesn't really make sense to me.
>>> 
>>> The code was introduced in ca5d1b3524b4 ("regulator: helpers: Modify
>>> helpers enabling multi-bit control"). I wonder if it was an 
>>> unintended
>>> consequence of the change? (original author CC-ed)
>>> 
>>>> +       .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.regmap = chip->regmap;
>>>> +       config.driver_data = chip;
>>>> +
>>>> +       config.of_node = dev->of_node;
>>>> +       config.init_data = of_get_regulator_init_data(dev, 
>>>> dev->of_node,
>>>> +                                                     &sy8106a_reg);
>>>> +
>>>> +       if (!config.init_data)
>>>> +               return -ENOMEM;
>>>> +
>>>> +       /* Probe regulator */
>>>> +       error = regmap_read(chip->regmap, SY8106A_REG_VOUT1_SEL,
>>>> &selector);
>>>> +       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)) {
>>>> +               error = PTR_ERR(rdev);
>>>> +               dev_err(&i2c->dev, "Failed to register SY8106A 
>>>> regulator:
>>>> %d\n", error);
>>>> +               return error;
>>>> +       }
>>>> +
>>>> +       chip->rdev = rdev;
>>>> +
>>>> +       i2c_set_clientdata(i2c, chip);
>>>> +
>>>> +       return 0;
>>>> +}
>>>> +
>>>> +static const struct of_device_id sy8106a_i2c_of_match[] = {
>>>> +       { .compatible = "silergy,sy8106a" },
>>>> +       { },
>>>> +};
>>>> +MODULE_DEVICE_TABLE(of, sy8106a_i2c_of_match);
>>>> +
>>>> +static const struct i2c_device_id sy8106a_i2c_id[] = {
>>>> +       { "sy8106a", 0 },
>>>> +       { },
>>>> +};
>>>> +MODULE_DEVICE_TABLE(i2c, sy8106a_i2c_id);
>>>> +
>>>> +static struct i2c_driver sy8106a_regulator_driver = {
>>>> +       .driver = {
>>>> +               .name = "sy8106a",
>>>> +               .of_match_table = 
>>>> of_match_ptr(sy8106a_i2c_of_match),
>>>> +       },
>>>> +       .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");
>>> 
>>> 
>>> This should be "GPL", to match what the license at the very top says.
>>> 
>>> Regards
>>> ChenYu
>>> 
>>>> --
>>>> 2.13.0
>>>> 
>>>> --
>>>> You received this message because you are subscribed to the Google 
>>>> Groups
>>>> "linux-sunxi" group.
>>>> To unsubscribe from this group and stop receiving emails from it, 
>>>> send an
>>>> email to linux-sunxi+unsubscribe@googlegroups.com.
>>>> For more options, visit https://groups.google.com/d/optout.
>>> 
>>> 
>>> _______________________________________________
>>> linux-arm-kernel mailing list
>>> linux-arm-kernel@lists.infradead.org
>>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>> 
>> 
>> --
>> You received this message because you are subscribed to the Google 
>> Groups
>> "linux-sunxi" group.
>> To unsubscribe from this group and stop receiving emails from it, send 
>> an
>> email to linux-sunxi+unsubscribe@googlegroups.com.
>> For more options, visit https://groups.google.com/d/optout.
Chen-Yu Tsai July 24, 2017, 6:17 a.m. | #5
On Mon, Jul 24, 2017 at 11:38 AM,  <icenowy@aosc.io> wrote:
> 在 2017-07-24 11:33,Chen-Yu Tsai 写道:
>>
>> On Mon, Jul 24, 2017 at 11:18 AM,  <icenowy@aosc.io> wrote:
>>>
>>> 在 2017-07-24 11:03,Chen-Yu Tsai 写道:
>>>>
>>>>
>>>> On Sun, Jul 23, 2017 at 6:27 PM, Icenowy Zheng <icenowy@aosc.io> wrote:
>>>>>
>>>>>
>>>>> From: Ondrej Jirman <megous@megous.com>
>>>>>
>>>>> SY8106A is an I2C attached single output regulator made by Silergy
>>>>> Corp,
>>>>> which is used on several Allwinner H3/H5 SBCs to control the power
>>>>> supply of the ARM cores.
>>>>>
>>>>> Add a driver for it.
>>>>>
>>>>> Signed-off-by: Ondrej Jirman <megous@megous.com>
>>>>> [Icenowy: Change commit message]
>>>>> Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
>>>>> ---
>>>>>  drivers/regulator/Kconfig             |   8 +-
>>>>>  drivers/regulator/Makefile            |   2 +-
>>>>>  drivers/regulator/sy8106a-regulator.c | 163
>>>>> ++++++++++++++++++++++++++++++++++
>>>>>  3 files changed, 171 insertions(+), 2 deletions(-)
>>>>>  create mode 100644 drivers/regulator/sy8106a-regulator.c
>>>>>
>>>>> diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
>>>>> index 99b9362331b5..1efa73e18d07 100644
>>>>> --- a/drivers/regulator/Kconfig
>>>>> +++ b/drivers/regulator/Kconfig
>>>>> @@ -764,6 +764,13 @@ config REGULATOR_STW481X_VMMC
>>>>>           This driver supports the internal VMMC regulator in the
>>>>> STw481x
>>>>>           PMIC chips.
>>>>>
>>>>> +config REGULATOR_SY8106A
>>>>> +       tristate "Silergy SY8106A regulator"
>>>>> +       depends on I2C && (OF || COMPILE_TEST)
>>>>> +       select REGMAP_I2C
>>>>> +       help
>>>>> +         This driver supports SY8106A single output regulator.
>>>>> +
>>>>>  config REGULATOR_TPS51632
>>>>>         tristate "TI TPS51632 Power Regulator"
>>>>>         depends on I2C
>>>>> @@ -938,4 +945,3 @@ config REGULATOR_WM8994
>>>>>           WM8994 CODEC.
>>>>>
>>>>>  endif
>>>>> -
>>>>> diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
>>>>> index 95b1e86ae692..f5120252f86a 100644
>>>>> --- a/drivers/regulator/Makefile
>>>>> +++ b/drivers/regulator/Makefile
>>>>> @@ -95,6 +95,7 @@ obj-$(CONFIG_REGULATOR_S2MPS11) += s2mps11.o
>>>>>  obj-$(CONFIG_REGULATOR_S5M8767) += s5m8767.o
>>>>>  obj-$(CONFIG_REGULATOR_SKY81452) += sky81452-regulator.o
>>>>>  obj-$(CONFIG_REGULATOR_STW481X_VMMC) += stw481x-vmmc.o
>>>>> +obj-$(CONFIG_REGULATOR_SY8106A) += sy8106a-regulator.o
>>>>>  obj-$(CONFIG_REGULATOR_TI_ABB) += ti-abb-regulator.o
>>>>>  obj-$(CONFIG_REGULATOR_TPS6105X) += tps6105x-regulator.o
>>>>>  obj-$(CONFIG_REGULATOR_TPS62360) += tps62360-regulator.o
>>>>> @@ -120,5 +121,4 @@ obj-$(CONFIG_REGULATOR_WM8350) +=
>>>>> wm8350-regulator.o
>>>>>  obj-$(CONFIG_REGULATOR_WM8400) += wm8400-regulator.o
>>>>>  obj-$(CONFIG_REGULATOR_WM8994) += wm8994-regulator.o
>>>>>
>>>>> -
>>>>>  ccflags-$(CONFIG_REGULATOR_DEBUG) += -DDEBUG
>>>>> diff --git a/drivers/regulator/sy8106a-regulator.c
>>>>> b/drivers/regulator/sy8106a-regulator.c
>>>>> new file mode 100644
>>>>> index 000000000000..1df889f68b3d
>>>>> --- /dev/null
>>>>> +++ b/drivers/regulator/sy8106a-regulator.c
>>>>> @@ -0,0 +1,163 @@
>>>>> +/*
>>>>> + * sy8106a-regulator.c - Regulator device driver for SY8106A
>>>>> + *
>>>>> + * Copyright (C) 2016 Ondřej Jirman <megous@megous.com>
>>>>> + *
>>>>> + * This program 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 program 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.
>>>>> + */
>>>>> +
>>>>> +#include <linux/err.h>
>>>>> +#include <linux/i2c.h>
>>>>> +#include <linux/module.h>
>>>>> +#include <linux/regmap.h>
>>>>> +#include <linux/regulator/driver.h>
>>>>> +#include <linux/regulator/of_regulator.h>
>>>>> +
>>>>> +#define SY8106A_REG_VOUT1_SEL          0x01
>>>>> +#define SY8106A_REG_VOUT_COM           0x02
>>>>> +#define SY8106A_REG_VOUT1_SEL_MASK     0x7f
>>>>> +#define SY8106A_DISABLE_REG            BIT(0)
>>>>> +#define SY8106A_GO_BIT                 BIT(7)
>>>>> +
>>>>> +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
>>>>> int sel)
>>>>> +{
>>>>> +       /* We use our set_voltage_sel in order to avoid unnecessary I2C
>>>>> +        * chatter, because the regulator_get_voltage_sel_regmap using
>>>>> +        * apply_bit would perform 4 unnecessary transfers instead of
>>>>> one,
>>>>> +        * increasing the chance of error.
>>>>> +        */
>>>>> +       return regmap_write(rdev->regmap, rdev->desc->vsel_reg,
>>>>> +                           sel | SY8106A_GO_BIT);
>>>>
>>>>
>>>>
>>>> There should also be an explanation of what the "go bit" does.
>>>> In this case it enables control of the voltage over I2C.
>>>>
>>>>> +}
>>>>> +
>>>>> +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,
>>>>
>>>>
>>>>
>>>> No enable/disable ops?
>>>>
>>>>> +};
>>>>> +
>>>>> +/* 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,
>>>>
>>>>
>>>>
>>>> As the regulator core helpers currently are, there is no way to disable
>>>> this regulator. regulator_disable_regmap looks like:
>>>
>>>
>>>
>>> By reading the current code, I think removing the disable_val variable
>>> will
>>> just make it work -- when enabling, the enable_reg will be set to
>>> disable_val
>>> (as enable_is_inverted is 1), and disable_val is defaultly 0; when
>>> disabling,
>>> the enable_reg will be set to enable_mask (fallbacked from enable_val,
>>> which
>>> is also the default value 0), and the regulator successfully get
>>> disabled.
>>
>>
>> (Gmail is wrapping the lines :( )
>>
>> enable_mask is set to SY8106A_DISABLE_REG, which equals disable_val here,
>> which is not 0. This is correct, as it is the bit mask passed to
>> regmap_update_bits. So no, it does not work.
>
>
> From my personal understanding of the code, the behavior of
> enable_is_inverted
> is that switch the roles of enable_val and disable_val, so if
> enable_is_inverted is set, the regulator_disable_regmap function will write
> enable_val (if it's 0, fallback to enable_mask) to the register, and
> regulator_enable_regmap will write disable_val.
>
> Maybe this design is used to ensure enable_val (then fallback to
> enable_mask)
> is not 0.

I think the changes needed to the core are probably too invasive, i.e.
affect too many other drivers, to be worth doing. Especially since we
won't really be using enable/disable much, as the regulator supplies
the CPU cores.

For now, lets just remove the enable/disable related fields, and leave
a TODO note citing the possibly required changes to the core instead.
You haven't assigned the callbacks anyway.

ChenYu

>
>
>>
>> It seems quite a lot of drivers depend on this fallback behavior though.
>>
>> ChenYu
>>
>>>
>>>>
>>>>         if (rdev->desc->enable_is_inverted) {
>>>>                 val = rdev->desc->enable_val;
>>>>                 if (!val)
>>>>                         val = rdev->desc->enable_mask;
>>>>         } else {
>>>>                 val = rdev->desc->disable_val;
>>>>         }
>>>>
>>>>         return regmap_update_bits(rdev->regmap, rdev->desc->enable_reg,
>>>>                                   rdev->desc->enable_mask, val);
>>>>
>>>> Note the fallback to enable_mask if enable_val is not set. The enable
>>>> helper has a similar structure. This regulator uses an enable value
>>>> of 0, and disable value of 1, it is impossible to get it right. As
>>>> it is now, it doesn't really make sense to me.
>>>>
>>>> The code was introduced in ca5d1b3524b4 ("regulator: helpers: Modify
>>>> helpers enabling multi-bit control"). I wonder if it was an unintended
>>>> consequence of the change? (original author CC-ed)
>>>>
>>>>> +       .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.regmap = chip->regmap;
>>>>> +       config.driver_data = chip;
>>>>> +
>>>>> +       config.of_node = dev->of_node;
>>>>> +       config.init_data = of_get_regulator_init_data(dev,
>>>>> dev->of_node,
>>>>> +                                                     &sy8106a_reg);
>>>>> +
>>>>> +       if (!config.init_data)
>>>>> +               return -ENOMEM;
>>>>> +
>>>>> +       /* Probe regulator */
>>>>> +       error = regmap_read(chip->regmap, SY8106A_REG_VOUT1_SEL,
>>>>> &selector);
>>>>> +       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)) {
>>>>> +               error = PTR_ERR(rdev);
>>>>> +               dev_err(&i2c->dev, "Failed to register SY8106A
>>>>> regulator:
>>>>> %d\n", error);
>>>>> +               return error;
>>>>> +       }
>>>>> +
>>>>> +       chip->rdev = rdev;
>>>>> +
>>>>> +       i2c_set_clientdata(i2c, chip);
>>>>> +
>>>>> +       return 0;
>>>>> +}
>>>>> +
>>>>> +static const struct of_device_id sy8106a_i2c_of_match[] = {
>>>>> +       { .compatible = "silergy,sy8106a" },
>>>>> +       { },
>>>>> +};
>>>>> +MODULE_DEVICE_TABLE(of, sy8106a_i2c_of_match);
>>>>> +
>>>>> +static const struct i2c_device_id sy8106a_i2c_id[] = {
>>>>> +       { "sy8106a", 0 },
>>>>> +       { },
>>>>> +};
>>>>> +MODULE_DEVICE_TABLE(i2c, sy8106a_i2c_id);
>>>>> +
>>>>> +static struct i2c_driver sy8106a_regulator_driver = {
>>>>> +       .driver = {
>>>>> +               .name = "sy8106a",
>>>>> +               .of_match_table = of_match_ptr(sy8106a_i2c_of_match),
>>>>> +       },
>>>>> +       .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");
>>>>
>>>>
>>>>
>>>> This should be "GPL", to match what the license at the very top says.
>>>>
>>>> Regards
>>>> ChenYu
>>>>
>>>>> --
>>>>> 2.13.0
>>>>>
>>>>> --
>>>>> You received this message because you are subscribed to the Google
>>>>> Groups
>>>>> "linux-sunxi" group.
>>>>> To unsubscribe from this group and stop receiving emails from it, send
>>>>> an
>>>>> email to linux-sunxi+unsubscribe@googlegroups.com.
>>>>> For more options, visit https://groups.google.com/d/optout.
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> linux-arm-kernel mailing list
>>>> linux-arm-kernel@lists.infradead.org
>>>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>>
>>>
>>>
>>> --
>>> You received this message because you are subscribed to the Google Groups
>>> "linux-sunxi" group.
>>> To unsubscribe from this group and stop receiving emails from it, send an
>>> email to linux-sunxi+unsubscribe@googlegroups.com.
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>
>
> --
> You received this message because you are subscribed to the Google Groups
> "linux-sunxi" group.
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Mark Brown July 24, 2017, 3:03 p.m. | #6
On Mon, Jul 24, 2017 at 11:03:24AM +0800, Chen-Yu Tsai wrote:
> On Sun, Jul 23, 2017 at 6:27 PM, Icenowy Zheng <icenowy@aosc.io> wrote:
> > From: Ondrej Jirman <megous@megous.com>
> >
> > SY8106A is an I2C attached single output regulator made by Silergy Corp,
> > which is used on several Allwinner H3/H5 SBCs to control the power
> > supply of the ARM cores.
> >
> > Add a driver for it.

Please delete unneeded context from mails when replying.  Doing this
makes it much easier to find your reply in the message, helping ensure
it won't be missed by people scrolling through the irrelevant quoted
material.

Patch

diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 99b9362331b5..1efa73e18d07 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -764,6 +764,13 @@  config REGULATOR_STW481X_VMMC
 	  This driver supports the internal VMMC regulator in the STw481x
 	  PMIC chips.
 
+config REGULATOR_SY8106A
+	tristate "Silergy SY8106A regulator"
+	depends on I2C && (OF || COMPILE_TEST)
+	select REGMAP_I2C
+	help
+	  This driver supports SY8106A single output regulator.
+
 config REGULATOR_TPS51632
 	tristate "TI TPS51632 Power Regulator"
 	depends on I2C
@@ -938,4 +945,3 @@  config REGULATOR_WM8994
 	  WM8994 CODEC.
 
 endif
-
diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
index 95b1e86ae692..f5120252f86a 100644
--- a/drivers/regulator/Makefile
+++ b/drivers/regulator/Makefile
@@ -95,6 +95,7 @@  obj-$(CONFIG_REGULATOR_S2MPS11) += s2mps11.o
 obj-$(CONFIG_REGULATOR_S5M8767) += s5m8767.o
 obj-$(CONFIG_REGULATOR_SKY81452) += sky81452-regulator.o
 obj-$(CONFIG_REGULATOR_STW481X_VMMC) += stw481x-vmmc.o
+obj-$(CONFIG_REGULATOR_SY8106A) += sy8106a-regulator.o
 obj-$(CONFIG_REGULATOR_TI_ABB) += ti-abb-regulator.o
 obj-$(CONFIG_REGULATOR_TPS6105X) += tps6105x-regulator.o
 obj-$(CONFIG_REGULATOR_TPS62360) += tps62360-regulator.o
@@ -120,5 +121,4 @@  obj-$(CONFIG_REGULATOR_WM8350) += wm8350-regulator.o
 obj-$(CONFIG_REGULATOR_WM8400) += wm8400-regulator.o
 obj-$(CONFIG_REGULATOR_WM8994) += wm8994-regulator.o
 
-
 ccflags-$(CONFIG_REGULATOR_DEBUG) += -DDEBUG
diff --git a/drivers/regulator/sy8106a-regulator.c b/drivers/regulator/sy8106a-regulator.c
new file mode 100644
index 000000000000..1df889f68b3d
--- /dev/null
+++ b/drivers/regulator/sy8106a-regulator.c
@@ -0,0 +1,163 @@ 
+/*
+ * sy8106a-regulator.c - Regulator device driver for SY8106A
+ *
+ * Copyright (C) 2016 Ondřej Jirman <megous@megous.com>
+ *
+ * This program 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 program 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.
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/of_regulator.h>
+
+#define SY8106A_REG_VOUT1_SEL		0x01
+#define SY8106A_REG_VOUT_COM		0x02
+#define SY8106A_REG_VOUT1_SEL_MASK	0x7f
+#define SY8106A_DISABLE_REG		BIT(0)
+#define SY8106A_GO_BIT			BIT(7)
+
+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 int sel)
+{
+	/* We use our set_voltage_sel in order to avoid unnecessary I2C
+	 * chatter, because the regulator_get_voltage_sel_regmap using
+	 * apply_bit would perform 4 unnecessary transfers instead of one,
+	 * increasing the chance of error.
+	 */
+	return regmap_write(rdev->regmap, rdev->desc->vsel_reg,
+			    sel | SY8106A_GO_BIT);
+}
+
+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.regmap = chip->regmap;
+	config.driver_data = chip;
+
+	config.of_node = dev->of_node;
+	config.init_data = of_get_regulator_init_data(dev, dev->of_node,
+						      &sy8106a_reg);
+
+	if (!config.init_data)
+		return -ENOMEM;
+
+	/* Probe regulator */
+	error = regmap_read(chip->regmap, SY8106A_REG_VOUT1_SEL, &selector);
+	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)) {
+		error = PTR_ERR(rdev);
+		dev_err(&i2c->dev, "Failed to register SY8106A regulator: %d\n", error);
+		return error;
+	}
+
+	chip->rdev = rdev;
+
+	i2c_set_clientdata(i2c, chip);
+
+	return 0;
+}
+
+static const struct of_device_id sy8106a_i2c_of_match[] = {
+	{ .compatible = "silergy,sy8106a" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, sy8106a_i2c_of_match);
+
+static const struct i2c_device_id sy8106a_i2c_id[] = {
+	{ "sy8106a", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(i2c, sy8106a_i2c_id);
+
+static struct i2c_driver sy8106a_regulator_driver = {
+	.driver = {
+		.name = "sy8106a",
+		.of_match_table	= of_match_ptr(sy8106a_i2c_of_match),
+	},
+	.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");