MAX8952 PMIC Driver Initial Release

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 <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
--
v2:
	- Style correction
	- Can accept platform_data with invalid GPIOs
	- Removed unnecessary features
	- Improved error handling
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

3 files changed, 369 insertions, 0 deletions

diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 172951b..4889caa 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -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
diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
index 8285fd8..beff6da 100644
--- a/drivers/regulator/Makefile
+++ b/drivers/regulator/Makefile
@@ -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
diff --git a/drivers/regulator/max8952.c b/drivers/regulator/max8952.c
new file mode 100644
index 0000000..f2af0b1
--- /dev/null
+++ b/drivers/regulator/max8952.c
@@ -0,0 +1,360 @@
+/*
+ * max8952.c - Voltage and current regulation for the Maxim 8952
+ *
+ * Copyright (C) 2010 Samsung Electronics
+ * MyungJoo Ham <myungjoo.ham@samsung.com>
+ *
+ * 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 <myungjoo.ham@samsung.com>");
+MODULE_LICENSE("GPL");