Re: [linux-sunxi] [PATCH 02/10] regulator: add support for SY8106A regulator

icenowy
2017-07-24T03:39:00Z

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
>>>>
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>>>
>>>
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>>
>>
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