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MAX8952 PMIC Driver Initial Release
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MAX8952 PMIC is used to provide voltage output between 770mV - 1400mV
with DVS support. In this initial release, users can set voltages for
four DVS modes, RAMP delay values, and SYNC frequency.
Controlling FPWM/SYNC_MODE/Pull-Down/Ramp Modes and reading CHIP_ID
is not supported in this release.

If GPIO of EN is not valid in platform data, the driver assumes that it
is always-on. If GPIO of VID0 or VID1 is invalid, the driver pulls down
VID0 and VID1 to fix DVS mode as 0 and disables DVS support.

We assume that V_OUT is capable to provide every voltage from 770mV to
1.40V in 10mV steps although the data sheet has some ambiguity on it.

Signed-off-by: MyungJoo Ham <[email protected]>
Signed-off-by: Kyungmin Park <[email protected]>
Acked-by: Mark Brown <[email protected]>
--
v2:
	- Style correction
	- Can accept platform_data with invalid GPIOs
	- Removed unnecessary features
	- Improved error handling
Signed-off-by: Liam Girdwood <[email protected]>
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@myungjoo
myungjoo authored and Liam Girdwood committed Oct 28, 2010
1 parent 2d3b07c commit 202f4f5
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8 changes: 8 additions & 0 deletions drivers/regulator/Kconfig
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Expand Up @@ -100,6 +100,14 @@ config REGULATOR_MAX8925
help
Say y here to support the voltage regulaltor of Maxim MAX8925 PMIC.

config REGULATOR_MAX8952
tristate "Maxim MAX8952 Power Management IC"
depends on I2C
help
This driver controls a Maxim 8952 voltage output regulator
via I2C bus. Maxim 8952 has one voltage output and supports 4 DVS
modes ranging from 0.77V to 1.40V by 0.01V steps.

config REGULATOR_MAX8998
tristate "Maxim 8998 voltage regulator"
depends on MFD_MAX8998
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1 change: 1 addition & 0 deletions drivers/regulator/Makefile
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Expand Up @@ -17,6 +17,7 @@ obj-$(CONFIG_REGULATOR_TWL4030) += twl-regulator.o
obj-$(CONFIG_REGULATOR_MAX8649) += max8649.o
obj-$(CONFIG_REGULATOR_MAX8660) += max8660.o
obj-$(CONFIG_REGULATOR_MAX8925) += max8925-regulator.o
obj-$(CONFIG_REGULATOR_MAX8952) += max8952.o
obj-$(CONFIG_REGULATOR_MAX8998) += max8998.o
obj-$(CONFIG_REGULATOR_WM831X) += wm831x-dcdc.o
obj-$(CONFIG_REGULATOR_WM831X) += wm831x-isink.o
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360 changes: 360 additions & 0 deletions drivers/regulator/max8952.c
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/*
* max8952.c - Voltage and current regulation for the Maxim 8952
*
* Copyright (C) 2010 Samsung Electronics
* MyungJoo Ham <[email protected]>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/

#include <linux/module.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/max8952.h>
#include <linux/mutex.h>
#include <linux/gpio.h>
#include <linux/io.h>
#include <linux/slab.h>

/* Registers */
enum {
MAX8952_REG_MODE0,
MAX8952_REG_MODE1,
MAX8952_REG_MODE2,
MAX8952_REG_MODE3,
MAX8952_REG_CONTROL,
MAX8952_REG_SYNC,
MAX8952_REG_RAMP,
MAX8952_REG_CHIP_ID1,
MAX8952_REG_CHIP_ID2,
};

struct max8952_data {
struct i2c_client *client;
struct device *dev;
struct mutex mutex;
struct max8952_platform_data *pdata;
struct regulator_dev *rdev;

bool vid0;
bool vid1;
bool en;
};

static int max8952_read_reg(struct max8952_data *max8952, u8 reg)
{
int ret = i2c_smbus_read_byte_data(max8952->client, reg);
if (ret > 0)
ret &= 0xff;

return ret;
}

static int max8952_write_reg(struct max8952_data *max8952,
u8 reg, u8 value)
{
return i2c_smbus_write_byte_data(max8952->client, reg, value);
}

static int max8952_voltage(struct max8952_data *max8952, u8 mode)
{
return (max8952->pdata->dvs_mode[mode] * 10 + 770) * 1000;
}

static int max8952_list_voltage(struct regulator_dev *rdev,
unsigned int selector)
{
struct max8952_data *max8952 = rdev_get_drvdata(rdev);

if (rdev_get_id(rdev) != 0)
return -EINVAL;

return max8952_voltage(max8952, selector);
}

static int max8952_is_enabled(struct regulator_dev *rdev)
{
struct max8952_data *max8952 = rdev_get_drvdata(rdev);
return max8952->en;
}

static int max8952_enable(struct regulator_dev *rdev)
{
struct max8952_data *max8952 = rdev_get_drvdata(rdev);

/* If not valid, assume "ALWAYS_HIGH" */
if (gpio_is_valid(max8952->pdata->gpio_en))
gpio_set_value(max8952->pdata->gpio_en, 1);

max8952->en = true;
return 0;
}

static int max8952_disable(struct regulator_dev *rdev)
{
struct max8952_data *max8952 = rdev_get_drvdata(rdev);

/* If not valid, assume "ALWAYS_HIGH" -> not permitted */
if (gpio_is_valid(max8952->pdata->gpio_en))
gpio_set_value(max8952->pdata->gpio_en, 0);
else
return -EPERM;

max8952->en = false;
return 0;
}

static int max8952_get_voltage(struct regulator_dev *rdev)
{
struct max8952_data *max8952 = rdev_get_drvdata(rdev);
u8 vid = 0;

if (max8952->vid0)
vid += 1;
if (max8952->vid1)
vid += 2;

return max8952_voltage(max8952, vid);
}

static int max8952_set_voltage(struct regulator_dev *rdev,
int min_uV, int max_uV)
{
struct max8952_data *max8952 = rdev_get_drvdata(rdev);
u8 vid = -1, i;

if (!gpio_is_valid(max8952->pdata->gpio_vid0) ||
!gpio_is_valid(max8952->pdata->gpio_vid0)) {
/* DVS not supported */
return -EPERM;
}

for (i = 0; i < MAX8952_NUM_DVS_MODE; i++) {
int volt = max8952_voltage(max8952, i);

/* Set the voltage as low as possible within the range */
if (volt <= max_uV && volt >= min_uV)
if (vid == -1 || max8952_voltage(max8952, vid) > volt)
vid = i;
}

if (vid >= 0 && vid < MAX8952_NUM_DVS_MODE) {
max8952->vid0 = (vid % 2 == 1);
max8952->vid1 = (((vid >> 1) % 2) == 1);
gpio_set_value(max8952->pdata->gpio_vid0, max8952->vid0);
gpio_set_value(max8952->pdata->gpio_vid1, max8952->vid1);
} else
return -EINVAL;

return 0;
}

static struct regulator_ops max8952_ops = {
.list_voltage = max8952_list_voltage,
.is_enabled = max8952_is_enabled,
.enable = max8952_enable,
.disable = max8952_disable,
.get_voltage = max8952_get_voltage,
.set_voltage = max8952_set_voltage,
.set_suspend_disable = max8952_disable,
};

static struct regulator_desc regulator = {
.name = "MAX8952_VOUT",
.id = 0,
.n_voltages = MAX8952_NUM_DVS_MODE,
.ops = &max8952_ops,
.type = REGULATOR_VOLTAGE,
.owner = THIS_MODULE,
};

static int __devinit max8952_pmic_probe(struct i2c_client *client,
const struct i2c_device_id *i2c_id)
{
struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
struct max8952_platform_data *pdata = client->dev.platform_data;
struct max8952_data *max8952;

int ret = 0, err = 0;

if (!pdata) {
dev_err(&client->dev, "Require the platform data\n");
return -EINVAL;
}

if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE))
return -EIO;

max8952 = kzalloc(sizeof(struct max8952_data), GFP_KERNEL);
if (!max8952)
return -ENOMEM;

max8952->client = client;
max8952->dev = &client->dev;
max8952->pdata = pdata;
mutex_init(&max8952->mutex);

max8952->rdev = regulator_register(&regulator, max8952->dev,
&pdata->reg_data, max8952);

ret = IS_ERR(max8952->rdev);
if (ret)
dev_err(max8952->dev, "regulator init failed (%d)\n", ret);

max8952->en = !!(pdata->reg_data.constraints.boot_on);
max8952->vid0 = (pdata->default_mode % 2) == 1;
max8952->vid1 = ((pdata->default_mode >> 1) % 2) == 1;

if (gpio_is_valid(pdata->gpio_en)) {
if (!gpio_request(pdata->gpio_en, "MAX8952 EN"))
gpio_direction_output(pdata->gpio_en, max8952->en);
else
err = 1;
} else
err = 2;

if (err) {
dev_info(max8952->dev, "EN gpio invalid: assume that EN"
"is always High\n");
max8952->en = 1;
pdata->gpio_en = -1; /* Mark invalid */
}

err = 0;

if (gpio_is_valid(pdata->gpio_vid0) &&
gpio_is_valid(pdata->gpio_vid1)) {
if (!gpio_request(pdata->gpio_vid0, "MAX8952 VID0"))
gpio_direction_output(pdata->gpio_vid0,
(pdata->default_mode) % 2);
else
err = 1;

if (!gpio_request(pdata->gpio_vid1, "MAX8952 VID1"))
gpio_direction_output(pdata->gpio_vid1,
(pdata->default_mode >> 1) % 2);
else {
if (!err)
gpio_free(pdata->gpio_vid0);
err = 2;
}

} else
err = 3;

if (err) {
dev_warn(max8952->dev, "VID0/1 gpio invalid: "
"DVS not avilable.\n");
max8952->vid0 = 0;
max8952->vid1 = 0;
/* Mark invalid */
pdata->gpio_vid0 = -1;
pdata->gpio_vid1 = -1;

/* Disable Pulldown of EN only */
max8952_write_reg(max8952, MAX8952_REG_CONTROL, 0x60);

dev_err(max8952->dev, "DVS modes disabled because VID0 and VID1"
" do not have proper controls.\n");
} else {
/*
* Disable Pulldown on EN, VID0, VID1 to reduce
* leakage current of MAX8952 assuming that MAX8952
* is turned on (EN==1). Note that without having VID0/1
* properly connected, turning pulldown off can be
* problematic. Thus, turn this off only when they are
* controllable by GPIO.
*/
max8952_write_reg(max8952, MAX8952_REG_CONTROL, 0x0);
}

max8952_write_reg(max8952, MAX8952_REG_MODE0,
(max8952_read_reg(max8952,
MAX8952_REG_MODE0) & 0xC0) |
(pdata->dvs_mode[0] & 0x3F));
max8952_write_reg(max8952, MAX8952_REG_MODE1,
(max8952_read_reg(max8952,
MAX8952_REG_MODE1) & 0xC0) |
(pdata->dvs_mode[1] & 0x3F));
max8952_write_reg(max8952, MAX8952_REG_MODE2,
(max8952_read_reg(max8952,
MAX8952_REG_MODE2) & 0xC0) |
(pdata->dvs_mode[2] & 0x3F));
max8952_write_reg(max8952, MAX8952_REG_MODE3,
(max8952_read_reg(max8952,
MAX8952_REG_MODE3) & 0xC0) |
(pdata->dvs_mode[3] & 0x3F));

max8952_write_reg(max8952, MAX8952_REG_SYNC,
(max8952_read_reg(max8952, MAX8952_REG_SYNC) & 0x3F) |
((pdata->sync_freq & 0x3) << 6));
max8952_write_reg(max8952, MAX8952_REG_RAMP,
(max8952_read_reg(max8952, MAX8952_REG_RAMP) & 0x1F) |
((pdata->ramp_speed & 0x7) << 5));

i2c_set_clientdata(client, max8952);

return ret;
}

static int __devexit max8952_pmic_remove(struct i2c_client *client)
{
struct max8952_data *max8952 = i2c_get_clientdata(client);
struct max8952_platform_data *pdata = max8952->pdata;
struct regulator_dev *rdev = max8952->rdev;

regulator_unregister(rdev);

gpio_free(pdata->gpio_vid0);
gpio_free(pdata->gpio_vid1);
gpio_free(pdata->gpio_en);

kfree(max8952);
return 0;
}

static const struct i2c_device_id max8952_ids[] = {
{ "max8952", 0 },
{ },
};
MODULE_DEVICE_TABLE(i2c, max8952_ids);

static struct i2c_driver max8952_pmic_driver = {
.probe = max8952_pmic_probe,
.remove = __devexit_p(max8952_pmic_remove),
.driver = {
.name = "max8952",
},
.id_table = max8952_ids,
};

static int __init max8952_pmic_init(void)
{
return i2c_add_driver(&max8952_pmic_driver);
}
subsys_initcall(max8952_pmic_init);

static void __exit max8952_pmic_exit(void)
{
i2c_del_driver(&max8952_pmic_driver);
}
module_exit(max8952_pmic_exit);

MODULE_DESCRIPTION("MAXIM 8952 voltage regulator driver");
MODULE_AUTHOR("MyungJoo Ham <[email protected]>");
MODULE_LICENSE("GPL");
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