Regulator: LP3972 PMIC regulator driver

This patch adds regulator drivers for National Semiconductors LP3972 PMIC.
This LP3972 PMIC controller has 3 DC/DC voltage converters and 5 low drop-out
(LDO) regulators. LP3972 PMIC controller uses I2C interface.
Signed-off-by: NAxel Lin <axel.lin@gmail.com>
Acked-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: NLiam Girdwood <lrg@slimlogic.co.uk>

drivers/regulator/Kconfig

@@ -172,6 +172,13 @@ config REGULATOR_LP3971
 	 Say Y here to support the voltage regulators and convertors
 	 on National Semiconductors LP3971 PMIC
 
+config REGULATOR_LP3972
+	tristate "National Semiconductors LP3972 PMIC regulator driver"
+	depends on I2C
+	help
+	 Say Y here to support the voltage regulators and convertors
+	 on National Semiconductors LP3972 PMIC
+
 config REGULATOR_PCAP
 	tristate "PCAP2 regulator driver"
 	depends on EZX_PCAP

drivers/regulator/Makefile

@@ -12,6 +12,7 @@ obj-$(CONFIG_REGULATOR_AD5398) += ad5398.o
 obj-$(CONFIG_REGULATOR_BQ24022) += bq24022.o
 obj-$(CONFIG_REGULATOR_DUMMY) += dummy.o
 obj-$(CONFIG_REGULATOR_LP3971) += lp3971.o
+obj-$(CONFIG_REGULATOR_LP3972) += lp3972.o
 obj-$(CONFIG_REGULATOR_MAX1586) += max1586.o
 obj-$(CONFIG_REGULATOR_TWL4030) += twl-regulator.o
 obj-$(CONFIG_REGULATOR_MAX8649)	+= max8649.o

drivers/regulator/lp3972.c

+/*
+ * Regulator driver for National Semiconductors LP3972 PMIC chip
+ *
+ * Based on lp3971.c
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/bug.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/lp3972.h>
+#include <linux/slab.h>
+
+struct lp3972 {
+	struct device *dev;
+	struct mutex io_lock;
+	struct i2c_client *i2c;
+	int num_regulators;
+	struct regulator_dev **rdev;
+};
+
+/* LP3972 Control Registers */
+#define LP3972_SCR_REG		0x07
+#define LP3972_OVER1_REG	0x10
+#define LP3972_OVSR1_REG	0x11
+#define LP3972_OVER2_REG	0x12
+#define LP3972_OVSR2_REG	0x13
+#define LP3972_VCC1_REG		0x20
+#define LP3972_ADTV1_REG	0x23
+#define LP3972_ADTV2_REG	0x24
+#define LP3972_AVRC_REG		0x25
+#define LP3972_CDTC1_REG	0x26
+#define LP3972_CDTC2_REG	0x27
+#define LP3972_SDTV1_REG	0x29
+#define LP3972_SDTV2_REG	0x2A
+#define LP3972_MDTV1_REG	0x32
+#define LP3972_MDTV2_REG	0x33
+#define LP3972_L2VCR_REG	0x39
+#define LP3972_L34VCR_REG	0x3A
+#define LP3972_SCR1_REG		0x80
+#define LP3972_SCR2_REG		0x81
+#define LP3972_OEN3_REG		0x82
+#define LP3972_OSR3_REG		0x83
+#define LP3972_LOER4_REG	0x84
+#define LP3972_B2TV_REG		0x85
+#define LP3972_B3TV_REG		0x86
+#define LP3972_B32RC_REG	0x87
+#define LP3972_ISRA_REG		0x88
+#define LP3972_BCCR_REG		0x89
+#define LP3972_II1RR_REG	0x8E
+#define LP3972_II2RR_REG	0x8F
+
+#define LP3972_SYS_CONTROL1_REG		LP3972_SCR1_REG
+/* System control register 1 initial value,
+ * bits 5, 6 and 7 are EPROM programmable */
+#define SYS_CONTROL1_INIT_VAL		0x02
+#define SYS_CONTROL1_INIT_MASK		0x1F
+
+#define LP3972_VOL_CHANGE_REG		LP3972_VCC1_REG
+#define LP3972_VOL_CHANGE_FLAG_GO	0x01
+#define LP3972_VOL_CHANGE_FLAG_MASK	0x03
+
+/* LDO output enable mask */
+#define LP3972_OEN3_L1EN	BIT(0)
+#define LP3972_OVER2_LDO2_EN	BIT(2)
+#define LP3972_OVER2_LDO3_EN	BIT(3)
+#define LP3972_OVER2_LDO4_EN	BIT(4)
+#define LP3972_OVER1_S_EN	BIT(2)
+
+static const int ldo1_voltage_map[] = {
+	1700, 1725, 1750, 1775, 1800, 1825, 1850, 1875,
+	1900, 1925, 1950, 1975, 2000,
+};
+
+static const int ldo23_voltage_map[] = {
+	1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500,
+	2600, 2700, 2800, 2900, 3000, 3100, 3200, 3300,
+};
+
+static const int ldo4_voltage_map[] = {
+	1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350,
+	1400, 1500, 1800, 1900, 2500, 2800, 3000, 3300,
+};
+
+static const int ldo5_voltage_map[] = {
+	   0,    0,    0,    0,    0,  850,  875,  900,
+	 925,  950,  975, 1000, 1025, 1050, 1075, 1100,
+	1125, 1150, 1175, 1200, 1225, 1250, 1275, 1300,
+	1325, 1350, 1375, 1400, 1425, 1450, 1475, 1500,
+};
+
+static const int buck1_voltage_map[] = {
+	 725,  750,  775,  800,  825,  850,  875,  900,
+	 925,  950,  975, 1000, 1025, 1050, 1075, 1100,
+	1125, 1150, 1175, 1200, 1225, 1250, 1275, 1300,
+	1325, 1350, 1375, 1400, 1425, 1450, 1475, 1500,
+};
+
+static const int buck23_voltage_map[] = {
+	   0,  800,  850,  900,  950, 1000, 1050, 1100,
+	1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500,
+	1550, 1600, 1650, 1700, 1800, 1900, 2500, 2800,
+	3000, 3300,
+};
+
+static const int *ldo_voltage_map[] = {
+	ldo1_voltage_map,
+	ldo23_voltage_map,
+	ldo23_voltage_map,
+	ldo4_voltage_map,
+	ldo5_voltage_map,
+};
+
+static const int *buck_voltage_map[] = {
+	buck1_voltage_map,
+	buck23_voltage_map,
+	buck23_voltage_map,
+};
+
+static const int ldo_output_enable_mask[] = {
+	LP3972_OEN3_L1EN,
+	LP3972_OVER2_LDO2_EN,
+	LP3972_OVER2_LDO3_EN,
+	LP3972_OVER2_LDO4_EN,
+	LP3972_OVER1_S_EN,
+};
+
+static const int ldo_output_enable_addr[] = {
+	LP3972_OEN3_REG,
+	LP3972_OVER2_REG,
+	LP3972_OVER2_REG,
+	LP3972_OVER2_REG,
+	LP3972_OVER1_REG,
+};
+
+static const int ldo_vol_ctl_addr[] = {
+	LP3972_MDTV1_REG,
+	LP3972_L2VCR_REG,
+	LP3972_L34VCR_REG,
+	LP3972_L34VCR_REG,
+	LP3972_SDTV1_REG,
+};
+
+static const int buck_vol_enable_addr[] = {
+	LP3972_OVER1_REG,
+	LP3972_OEN3_REG,
+	LP3972_OEN3_REG,
+};
+
+static const int buck_base_addr[] = {
+	LP3972_ADTV1_REG,
+	LP3972_B2TV_REG,
+	LP3972_B3TV_REG,
+};
+
+#define LP3972_LDO_VOL_VALUE_MAP(x) (ldo_voltage_map[x])
+#define LP3972_LDO_OUTPUT_ENABLE_MASK(x) (ldo_output_enable_mask[x])
+#define LP3972_LDO_OUTPUT_ENABLE_REG(x) (ldo_output_enable_addr[x])
+
+/*	LDO voltage control registers shift:
+	LP3972_LDO1 -> 0, LP3972_LDO2 -> 4
+	LP3972_LDO3 -> 0, LP3972_LDO4 -> 4
+	LP3972_LDO5 -> 0
+*/
+#define LP3972_LDO_VOL_CONTR_SHIFT(x) (((x) & 1) << 2)
+#define LP3972_LDO_VOL_CONTR_REG(x) (ldo_vol_ctl_addr[x])
+#define LP3972_LDO_VOL_CHANGE_SHIFT(x) ((x) ? 4 : 6)
+
+#define LP3972_LDO_VOL_MASK(x) (((x) % 4) ? 0x0f : 0x1f)
+#define LP3972_LDO_VOL_MIN_IDX(x) (((x) == 4) ? 0x05 : 0x00)
+#define LP3972_LDO_VOL_MAX_IDX(x) ((x) ? (((x) == 4) ? 0x1f : 0x0f) : 0x0c)
+
+#define LP3972_BUCK_VOL_VALUE_MAP(x) (buck_voltage_map[x])
+#define LP3972_BUCK_VOL_ENABLE_REG(x) (buck_vol_enable_addr[x])
+#define LP3972_BUCK_VOL1_REG(x) (buck_base_addr[x])
+#define LP3972_BUCK_VOL_MASK 0x1f
+#define LP3972_BUCK_VOL_MIN_IDX(x) ((x) ? 0x01 : 0x00)
+#define LP3972_BUCK_VOL_MAX_IDX(x) ((x) ? 0x19 : 0x1f)
+
+static int lp3972_i2c_read(struct i2c_client *i2c, char reg, int count,
+	u16 *dest)
+{
+	int ret;
+
+	if (count != 1)
+		return -EIO;
+	ret = i2c_smbus_read_byte_data(i2c, reg);
+	if (ret < 0)
+		return -EIO;
+
+	*dest = ret;
+	return 0;
+}
+
+static int lp3972_i2c_write(struct i2c_client *i2c, char reg, int count,
+	const u16 *src)
+{
+	if (count != 1)
+		return -EIO;
+	return i2c_smbus_write_byte_data(i2c, reg, *src);
+}
+
+static u8 lp3972_reg_read(struct lp3972 *lp3972, u8 reg)
+{
+	u16 val = 0;
+
+	mutex_lock(&lp3972->io_lock);
+
+	lp3972_i2c_read(lp3972->i2c, reg, 1, &val);
+
+	dev_dbg(lp3972->dev, "reg read 0x%02x -> 0x%02x\n", (int)reg,
+		(unsigned)val&0xff);
+
+	mutex_unlock(&lp3972->io_lock);
+
+	return val & 0xff;
+}
+
+static int lp3972_set_bits(struct lp3972 *lp3972, u8 reg, u16 mask, u16 val)
+{
+	u16 tmp;
+	int ret;
+
+	mutex_lock(&lp3972->io_lock);
+
+	ret = lp3972_i2c_read(lp3972->i2c, reg, 1, &tmp);
+	tmp = (tmp & ~mask) | val;
+	if (ret == 0) {
+		ret = lp3972_i2c_write(lp3972->i2c, reg, 1, &tmp);
+		dev_dbg(lp3972->dev, "reg write 0x%02x -> 0x%02x\n", (int)reg,
+			(unsigned)val&0xff);
+	}
+	mutex_unlock(&lp3972->io_lock);
+
+	return ret;
+}
+
+static int lp3972_ldo_list_voltage(struct regulator_dev *dev, unsigned index)
+{
+	int ldo = rdev_get_id(dev) - LP3972_LDO1;
+	return 1000 * LP3972_LDO_VOL_VALUE_MAP(ldo)[index];
+}
+
+static int lp3972_ldo_is_enabled(struct regulator_dev *dev)
+{
+	struct lp3972 *lp3972 = rdev_get_drvdata(dev);
+	int ldo = rdev_get_id(dev) - LP3972_LDO1;
+	u16 mask = LP3972_LDO_OUTPUT_ENABLE_MASK(ldo);
+	u16 val;
+
+	val = lp3972_reg_read(lp3972, LP3972_LDO_OUTPUT_ENABLE_REG(ldo));
+	return !!(val & mask);
+}
+
+static int lp3972_ldo_enable(struct regulator_dev *dev)
+{
+	struct lp3972 *lp3972 = rdev_get_drvdata(dev);
+	int ldo = rdev_get_id(dev) - LP3972_LDO1;
+	u16 mask = LP3972_LDO_OUTPUT_ENABLE_MASK(ldo);
+
+	return lp3972_set_bits(lp3972, LP3972_LDO_OUTPUT_ENABLE_REG(ldo),
+				mask, mask);
+}
+
+static int lp3972_ldo_disable(struct regulator_dev *dev)
+{
+	struct lp3972 *lp3972 = rdev_get_drvdata(dev);
+	int ldo = rdev_get_id(dev) - LP3972_LDO1;
+	u16 mask = LP3972_LDO_OUTPUT_ENABLE_MASK(ldo);
+
+	return lp3972_set_bits(lp3972, LP3972_LDO_OUTPUT_ENABLE_REG(ldo),
+				mask, 0);
+}
+
+static int lp3972_ldo_get_voltage(struct regulator_dev *dev)
+{
+	struct lp3972 *lp3972 = rdev_get_drvdata(dev);
+	int ldo = rdev_get_id(dev) - LP3972_LDO1;
+	u16 mask = LP3972_LDO_VOL_MASK(ldo);
+	u16 val, reg;
+
+	reg = lp3972_reg_read(lp3972, LP3972_LDO_VOL_CONTR_REG(ldo));
+	val = (reg >> LP3972_LDO_VOL_CONTR_SHIFT(ldo)) & mask;
+
+	return 1000 * LP3972_LDO_VOL_VALUE_MAP(ldo)[val];
+}
+
+static int lp3972_ldo_set_voltage(struct regulator_dev *dev,
+				  int min_uV, int max_uV)
+{
+	struct lp3972 *lp3972 = rdev_get_drvdata(dev);
+	int ldo = rdev_get_id(dev) - LP3972_LDO1;
+	int min_vol = min_uV / 1000, max_vol = max_uV / 1000;
+	const int *vol_map = LP3972_LDO_VOL_VALUE_MAP(ldo);
+	u16 val;
+	int shift, ret;
+
+	if (min_vol < vol_map[LP3972_LDO_VOL_MIN_IDX(ldo)] ||
+	    min_vol > vol_map[LP3972_LDO_VOL_MAX_IDX(ldo)])
+		return -EINVAL;
+
+	for (val = LP3972_LDO_VOL_MIN_IDX(ldo);
+		val <= LP3972_LDO_VOL_MAX_IDX(ldo); val++)
+		if (vol_map[val] >= min_vol)
+			break;
+
+	if (val > LP3972_LDO_VOL_MAX_IDX(ldo) || vol_map[val] > max_vol)
+		return -EINVAL;
+
+	shift = LP3972_LDO_VOL_CONTR_SHIFT(ldo);
+	ret = lp3972_set_bits(lp3972, LP3972_LDO_VOL_CONTR_REG(ldo),
+		LP3972_LDO_VOL_MASK(ldo) << shift, val << shift);
+
+	if (ret)
+		return ret;
+
+	switch (ldo) {
+	case LP3972_LDO1:
+	case LP3972_LDO5:
+		shift = LP3972_LDO_VOL_CHANGE_SHIFT(ldo);
+		ret = lp3972_set_bits(lp3972, LP3972_VOL_CHANGE_REG,
+			LP3972_VOL_CHANGE_FLAG_MASK << shift,
+			LP3972_VOL_CHANGE_FLAG_GO << shift);
+		if (ret)
+			return ret;
+
+		ret = lp3972_set_bits(lp3972, LP3972_VOL_CHANGE_REG,
+			LP3972_VOL_CHANGE_FLAG_MASK << shift, 0);
+		break;
+	}
+
+	return ret;
+}
+
+static struct regulator_ops lp3972_ldo_ops = {
+	.list_voltage = lp3972_ldo_list_voltage,
+	.is_enabled = lp3972_ldo_is_enabled,
+	.enable = lp3972_ldo_enable,
+	.disable = lp3972_ldo_disable,
+	.get_voltage = lp3972_ldo_get_voltage,
+	.set_voltage = lp3972_ldo_set_voltage,
+};
+
+static int lp3972_dcdc_list_voltage(struct regulator_dev *dev, unsigned index)
+{
+	int buck = rdev_get_id(dev) - LP3972_DCDC1;
+	return 1000 * buck_voltage_map[buck][index];
+}
+
+static int lp3972_dcdc_is_enabled(struct regulator_dev *dev)
+{
+	struct lp3972 *lp3972 = rdev_get_drvdata(dev);
+	int buck = rdev_get_id(dev) - LP3972_DCDC1;
+	u16 mask = 1 << (buck * 2);
+	u16 val;
+
+	val = lp3972_reg_read(lp3972, LP3972_BUCK_VOL_ENABLE_REG(buck));
+	return !!(val & mask);
+}
+
+static int lp3972_dcdc_enable(struct regulator_dev *dev)
+{
+	struct lp3972 *lp3972 = rdev_get_drvdata(dev);
+	int buck = rdev_get_id(dev) - LP3972_DCDC1;
+	u16 mask = 1 << (buck * 2);
+	u16 val;
+
+	val = lp3972_set_bits(lp3972, LP3972_BUCK_VOL_ENABLE_REG(buck),
+				mask, mask);
+	return val;
+}
+
+static int lp3972_dcdc_disable(struct regulator_dev *dev)
+{
+	struct lp3972 *lp3972 = rdev_get_drvdata(dev);
+	int buck = rdev_get_id(dev) - LP3972_DCDC1;
+	u16 mask = 1 << (buck * 2);
+	u16 val;
+
+	val = lp3972_set_bits(lp3972, LP3972_BUCK_VOL_ENABLE_REG(buck),
+				mask, 0);
+	return val;
+}
+
+static int lp3972_dcdc_get_voltage(struct regulator_dev *dev)
+{
+	struct lp3972 *lp3972 = rdev_get_drvdata(dev);
+	int buck = rdev_get_id(dev) - LP3972_DCDC1;
+	u16 reg;
+	int val;
+
+	reg = lp3972_reg_read(lp3972, LP3972_BUCK_VOL1_REG(buck));
+	reg &= LP3972_BUCK_VOL_MASK;
+	if (reg <= LP3972_BUCK_VOL_MAX_IDX(buck))
+		val = 1000 * buck_voltage_map[buck][reg];
+	else {
+		val = 0;
+		dev_warn(&dev->dev, "chip reported incorrect voltage value.\n");
+	}
+
+	return val;
+}
+
+static int lp3972_dcdc_set_voltage(struct regulator_dev *dev,
+				  int min_uV, int max_uV)
+{
+	struct lp3972 *lp3972 = rdev_get_drvdata(dev);
+	int buck = rdev_get_id(dev) - LP3972_DCDC1;
+	int min_vol = min_uV / 1000, max_vol = max_uV / 1000;
+	const int *vol_map = buck_voltage_map[buck];
+	u16 val;
+	int ret;
+
+	if (min_vol < vol_map[LP3972_BUCK_VOL_MIN_IDX(buck)] ||
+	    min_vol > vol_map[LP3972_BUCK_VOL_MAX_IDX(buck)])
+		return -EINVAL;
+
+	for (val = LP3972_BUCK_VOL_MIN_IDX(buck);
+		val <= LP3972_BUCK_VOL_MAX_IDX(buck); val++)
+		if (vol_map[val] >= min_vol)
+			break;
+
+	if (val > LP3972_BUCK_VOL_MAX_IDX(buck) ||
+	    vol_map[val] > max_vol)
+		return -EINVAL;
+
+	ret = lp3972_set_bits(lp3972, LP3972_BUCK_VOL1_REG(buck),
+				LP3972_BUCK_VOL_MASK, val);
+	if (ret)
+		return ret;
+
+	if (buck != 0)
+		return ret;
+
+	ret = lp3972_set_bits(lp3972, LP3972_VOL_CHANGE_REG,
+		LP3972_VOL_CHANGE_FLAG_MASK, LP3972_VOL_CHANGE_FLAG_GO);
+	if (ret)
+		return ret;
+
+	return lp3972_set_bits(lp3972, LP3972_VOL_CHANGE_REG,
+				LP3972_VOL_CHANGE_FLAG_MASK, 0);
+}
+
+static struct regulator_ops lp3972_dcdc_ops = {
+	.list_voltage = lp3972_dcdc_list_voltage,
+	.is_enabled = lp3972_dcdc_is_enabled,
+	.enable = lp3972_dcdc_enable,
+	.disable = lp3972_dcdc_disable,
+	.get_voltage = lp3972_dcdc_get_voltage,
+	.set_voltage = lp3972_dcdc_set_voltage,
+};
+
+static struct regulator_desc regulators[] = {
+	{
+		.name = "LDO1",
+		.id = LP3972_LDO1,
+		.ops = &lp3972_ldo_ops,
+		.n_voltages = ARRAY_SIZE(ldo1_voltage_map),
+		.type = REGULATOR_VOLTAGE,
+		.owner = THIS_MODULE,
+	},
+	{
+		.name = "LDO2",
+		.id = LP3972_LDO2,
+		.ops = &lp3972_ldo_ops,
+		.n_voltages = ARRAY_SIZE(ldo23_voltage_map),
+		.type = REGULATOR_VOLTAGE,
+		.owner = THIS_MODULE,
+	},
+	{
+		.name = "LDO3",
+		.id = LP3972_LDO3,
+		.ops = &lp3972_ldo_ops,
+		.n_voltages = ARRAY_SIZE(ldo23_voltage_map),
+		.type = REGULATOR_VOLTAGE,
+		.owner = THIS_MODULE,
+	},
+	{
+		.name = "LDO4",
+		.id = LP3972_LDO4,
+		.ops = &lp3972_ldo_ops,
+		.n_voltages = ARRAY_SIZE(ldo4_voltage_map),
+		.type = REGULATOR_VOLTAGE,
+		.owner = THIS_MODULE,
+	},
+	{
+		.name = "LDO5",
+		.id = LP3972_LDO5,
+		.ops = &lp3972_ldo_ops,
+		.n_voltages = ARRAY_SIZE(ldo5_voltage_map),
+		.type = REGULATOR_VOLTAGE,
+		.owner = THIS_MODULE,
+	},
+	{
+		.name = "DCDC1",
+		.id = LP3972_DCDC1,
+		.ops = &lp3972_dcdc_ops,
+		.n_voltages = ARRAY_SIZE(buck1_voltage_map),
+		.type = REGULATOR_VOLTAGE,
+		.owner = THIS_MODULE,
+	},
+	{
+		.name = "DCDC2",
+		.id = LP3972_DCDC2,
+		.ops = &lp3972_dcdc_ops,
+		.n_voltages = ARRAY_SIZE(buck23_voltage_map),
+		.type = REGULATOR_VOLTAGE,
+		.owner = THIS_MODULE,
+	},
+	{
+		.name = "DCDC3",
+		.id = LP3972_DCDC3,
+		.ops = &lp3972_dcdc_ops,
+		.n_voltages = ARRAY_SIZE(buck23_voltage_map),
+		.type = REGULATOR_VOLTAGE,
+		.owner = THIS_MODULE,
+	},
+};
+
+static int setup_regulators(struct lp3972 *lp3972,
+	struct lp3972_platform_data *pdata)
+{
+	int i, err;
+
+	lp3972->num_regulators = pdata->num_regulators;
+	lp3972->rdev = kcalloc(pdata->num_regulators,
+				sizeof(struct regulator_dev *), GFP_KERNEL);
+	if (!lp3972->rdev) {
+		err = -ENOMEM;
+		goto err_nomem;
+	}
+
+	/* Instantiate the regulators */
+	for (i = 0; i < pdata->num_regulators; i++) {
+		struct lp3972_regulator_subdev *reg = &pdata->regulators[i];
+		lp3972->rdev[i] = regulator_register(&regulators[reg->id],
+					lp3972->dev, reg->initdata, lp3972);
+
+		if (IS_ERR(lp3972->rdev[i])) {
+			err = PTR_ERR(lp3972->rdev[i]);
+			dev_err(lp3972->dev, "regulator init failed: %d\n",
+				err);
+			goto error;
+		}
+	}
+
+	return 0;
+error:
+	while (--i >= 0)
+		regulator_unregister(lp3972->rdev[i]);
+	kfree(lp3972->rdev);
+	lp3972->rdev = NULL;
+err_nomem:
+	return err;
+}
+
+static int __devinit lp3972_i2c_probe(struct i2c_client *i2c,
+			    const struct i2c_device_id *id)
+{
+	struct lp3972 *lp3972;
+	struct lp3972_platform_data *pdata = i2c->dev.platform_data;
+	int ret;
+	u16 val;
+
+	if (!pdata) {
+		dev_dbg(&i2c->dev, "No platform init data supplied\n");
+		return -ENODEV;
+	}
+
+	lp3972 = kzalloc(sizeof(struct lp3972), GFP_KERNEL);
+	if (!lp3972)
+		return -ENOMEM;
+
+	lp3972->i2c = i2c;
+	lp3972->dev = &i2c->dev;
+
+	mutex_init(&lp3972->io_lock);
+
+	/* Detect LP3972 */
+	ret = lp3972_i2c_read(i2c, LP3972_SYS_CONTROL1_REG, 1, &val);
+	if (ret == 0 && (val & SYS_CONTROL1_INIT_MASK) != SYS_CONTROL1_INIT_VAL)
+		ret = -ENODEV;
+	if (ret < 0) {
+		dev_err(&i2c->dev, "failed to detect device\n");
+		goto err_detect;
+	}
+
+	ret = setup_regulators(lp3972, pdata);
+	if (ret < 0)
+		goto err_detect;
+
+	i2c_set_clientdata(i2c, lp3972);
+	return 0;
+
+err_detect:
+	kfree(lp3972);
+	return ret;
+}
+
+static int __devexit lp3972_i2c_remove(struct i2c_client *i2c)
+{
+	struct lp3972 *lp3972 = i2c_get_clientdata(i2c);
+	int i;
+
+	for (i = 0; i < lp3972->num_regulators; i++)
+		regulator_unregister(lp3972->rdev[i]);
+	kfree(lp3972->rdev);
+	kfree(lp3972);
+
+	return 0;
+}
+
+static const struct i2c_device_id lp3972_i2c_id[] = {
+	{ "lp3972", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, lp3972_i2c_id);
+
+static struct i2c_driver lp3972_i2c_driver = {
+	.driver = {
+		.name = "lp3972",
+		.owner = THIS_MODULE,
+	},
+	.probe    = lp3972_i2c_probe,
+	.remove   = __devexit_p(lp3972_i2c_remove),
+	.id_table = lp3972_i2c_id,
+};
+
+static int __init lp3972_module_init(void)
+{
+	return i2c_add_driver(&lp3972_i2c_driver);
+}
+subsys_initcall(lp3972_module_init);
+
+static void __exit lp3972_module_exit(void)
+{
+	i2c_del_driver(&lp3972_i2c_driver);
+}
+module_exit(lp3972_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Axel Lin <axel.lin@gmail.com>");
+MODULE_DESCRIPTION("LP3972 PMIC driver");

include/linux/regulator/lp3972.h

+/*
+ * National Semiconductors LP3972 PMIC chip client interface
+ *
+ * Based on lp3971.h
+ *
+ * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef __LINUX_REGULATOR_LP3972_H
+#define __LINUX_REGULATOR_LP3972_H
+
+#include <linux/regulator/machine.h>
+
+#define LP3972_LDO1  0
+#define LP3972_LDO2  1
+#define LP3972_LDO3  2
+#define LP3972_LDO4  3
+#define LP3972_LDO5  4
+
+#define LP3972_DCDC1 5
+#define LP3972_DCDC2 6
+#define LP3972_DCDC3 7
+
+#define LP3972_NUM_REGULATORS 8
+
+struct lp3972_regulator_subdev {
+	int id;
+	struct regulator_init_data *initdata;
+};
+
+struct lp3972_platform_data {
+	int num_regulators;
+	struct lp3972_regulator_subdev *regulators;
+};
+
+#endif