Date:   Mon, 24 Jul 2017 11:18:07 +0800
From:   icenowy@...c.io
To:     Chen-Yu Tsai <wens@...e.org>
Cc:     Ondrej Jirman <megous@...ous.com>,
        devicetree <devicetree@...r.kernel.org>,
        "open list:THERMAL" <linux-pm@...r.kernel.org>,
        linux-sunxi <linux-sunxi@...glegroups.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Carlo Caione <carlo@...one.org>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>,
        linux-clk <linux-clk@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [linux-sunxi] [PATCH 02/10] regulator: add support for SY8106A
 regulator

在 2017-07-24 11:03，Chen-Yu Tsai 写道：
> On Sun, Jul 23, 2017 at 6:27 PM, Icenowy Zheng <icenowy@...c.io> wrote:
>> From: Ondrej Jirman <megous@...ous.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@...ous.com>
>> [Icenowy: Change commit message]
>> Signed-off-by: Icenowy Zheng <icenowy@...c.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@...ous.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@...ous.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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