[PATCH] Add ltc3562 voltage regulator driver

[Mike Looijmans <mike.looijmans@topic.nl>]

The ltc3562 is an I2C controlled regulator supporting 4 independent
outputs.

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
---
 drivers/regulator/Kconfig   |    7 +
 drivers/regulator/Makefile  |    1 +
 drivers/regulator/ltc3562.c |  387 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 395 insertions(+)
 create mode 100644 drivers/regulator/ltc3562.c

diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 55d7b7b..4012601 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -300,6 +300,13 @@ config REGULATOR_LP8788
 	help
 	  This driver supports LP8788 voltage regulator chip.
 
+config REGULATOR_LTC3562
+	tristate "LCT3562 quad output voltage regulator"
+	depends on I2C
+	help
+	  This enables support for the LCT3562 quad output voltage regulator
+	  controlled via I2C.
+
 config REGULATOR_LTC3589
 	tristate "LTC3589 8-output voltage regulator"
 	depends on I2C
diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
index 1029ed3..9a15146 100644
--- a/drivers/regulator/Makefile
+++ b/drivers/regulator/Makefile
@@ -41,6 +41,7 @@ obj-$(CONFIG_REGULATOR_LP872X) += lp872x.o
 obj-$(CONFIG_REGULATOR_LP8788) += lp8788-buck.o
 obj-$(CONFIG_REGULATOR_LP8788) += lp8788-ldo.o
 obj-$(CONFIG_REGULATOR_LP8755) += lp8755.o
+obj-$(CONFIG_REGULATOR_LTC3562) += ltc3562.o
 obj-$(CONFIG_REGULATOR_LTC3589) += ltc3589.o
 obj-$(CONFIG_REGULATOR_MAX14577) += max14577.o
 obj-$(CONFIG_REGULATOR_MAX1586) += max1586.o
diff --git a/drivers/regulator/ltc3562.c b/drivers/regulator/ltc3562.c
new file mode 100644
index 0000000..be111bc
--- /dev/null
+++ b/drivers/regulator/ltc3562.c
@@ -0,0 +1,387 @@
+/*
+ * Regulator driver for Linear Technology LTC3562
+ *
+ *  Copyright (C) 2014 Topic Embedded Products
+ *
+ * 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/module.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+#include <linux/slab.h>
+#include <linux/regulator/of_regulator.h>
+
+#define LTC3562_NUM_REGULATORS	4
+
+#define REGULATOR_TYPE_A_NUM_VOLTAGES	16
+#define REGULATOR_TYPE_A_MIN_UV	425000
+#define REGULATOR_TYPE_A_UV_STEP	25000
+
+#define REGULATOR_TYPE_B_NUM_VOLTAGES	128
+#define REGULATOR_TYPE_B_MIN_UV	600000
+#define REGULATOR_TYPE_B_UV_STEP	25000
+
+struct ltc3562_status {
+	u8 shadow_addr;		/* Shadow register of address byte */
+	u8 shadow_data;		/* Shadow register of data byte */
+	u8 voltage_set;		/* Check if voltage has been set before */
+};
+
+struct ltc3562 {
+	struct device *dev;
+	struct i2c_client *i2c;
+	struct mutex mutex;
+	struct regulator_dev *rdev[LTC3562_NUM_REGULATORS];
+	struct ltc3562_status rstatus[LTC3562_NUM_REGULATORS];
+};
+
+static int ltc3562_write(struct i2c_client *i2c, u8 reg_a, u8 reg_b);
+static int ltc3562_dummy_write(struct i2c_client *i2c);
+
+#define LTC3562_R400B_ID	0x00
+#define LTC3562_R600B_ID	0x01
+#define LTC3562_R400A_ID	0x02
+#define LTC3562_R600A_ID	0x03
+
+#define OPERATING_MODE_MASK	0x03
+
+#define PROGRAM_R400B_MASK	0x10
+#define PROGRAM_R600B_MASK	0x20
+#define PROGRAM_R400A_MASK	0x40
+#define PROGRAM_R600A_MASK	0x80
+
+#define OPERATING_MODE_PULSE_SKIP	0x00
+#define OPERATING_MODE_LDO		0x01
+#define OPERATING_MODE_FOCED_BURST	0x02
+#define OPERATING_MODE_BURST		0x03
+
+#define REGULATOR_ENABLE_BIT	0x80
+
+
+static int ltc3562_regulator_enable(struct regulator_dev *dev)
+{
+	int ret, v_index;
+	unsigned int v_default;
+	struct ltc3562 *ltc3562 = rdev_get_drvdata(dev);
+	int id = rdev_get_id(dev);
+	struct ltc3562_status *status = &ltc3562->rstatus[id];
+
+	mutex_lock(&ltc3562->mutex);
+
+	if (!status->voltage_set) {
+		if (of_property_read_u32(dev->dev.of_node,
+			"ltc3562-default-voltage", &v_default) == 0) {
+			v_index = dev->desc->ops->map_voltage(
+				dev, v_default, v_default);
+			if (v_index > 0)
+				status->shadow_data =
+					v_index & (~REGULATOR_ENABLE_BIT);
+			status->voltage_set = 1;
+		}
+	}
+
+	status->shadow_data |= REGULATOR_ENABLE_BIT;
+
+	ret = ltc3562_write(ltc3562->i2c,
+		status->shadow_addr | PROGRAM_R400B_MASK << id,
+		status->shadow_data);
+
+	mutex_unlock(&ltc3562->mutex);
+
+	return ret;
+}
+
+static int ltc3562_regulator_disable(struct regulator_dev *dev)
+{
+	int ret;
+	struct ltc3562 *ltc3562 = rdev_get_drvdata(dev);
+	int id = rdev_get_id(dev);
+	struct ltc3562_status *status = &ltc3562->rstatus[id];
+
+	mutex_lock(&ltc3562->mutex);
+
+	status->shadow_data &= ~(REGULATOR_ENABLE_BIT);
+
+	ret = ltc3562_write(ltc3562->i2c,
+		status->shadow_addr, status->shadow_data);
+
+	mutex_unlock(&ltc3562->mutex);
+
+	return ret;
+}
+
+static int ltc3562_regulator_is_enabled(struct regulator_dev *dev)
+{
+	int ret;
+	struct ltc3562 *ltc3562 = rdev_get_drvdata(dev);
+	int id = rdev_get_id(dev);
+	struct ltc3562_status *status = &ltc3562->rstatus[id];
+
+	mutex_lock(&ltc3562->mutex);
+
+	ret = (status->shadow_data & REGULATOR_ENABLE_BIT) ? 1 : 0;
+
+	mutex_unlock(&ltc3562->mutex);
+
+	return ret;
+}
+
+static int ltc3562_set_voltage_sel(struct regulator_dev *dev,
+	unsigned int selector)
+{
+	int ret;
+	struct ltc3562 *ltc3562 = rdev_get_drvdata(dev);
+	int id = rdev_get_id(dev);
+	struct ltc3562_status *status = &ltc3562->rstatus[id];
+
+	mutex_lock(&ltc3562->mutex);
+
+	status->shadow_data =
+		(status->shadow_data & REGULATOR_ENABLE_BIT) | selector;
+	status->voltage_set = 1;
+
+	ret = ltc3562_write(ltc3562->i2c,
+		status->shadow_addr, status->shadow_data);
+
+	mutex_unlock(&ltc3562->mutex);
+
+	return ret;
+}
+
+static int ltc3562_get_voltage_sel(struct regulator_dev *dev)
+{
+	int ret;
+	struct ltc3562 *ltc3562 = rdev_get_drvdata(dev);
+	int id = rdev_get_id(dev);
+	struct ltc3562_status *status = &ltc3562->rstatus[id];
+
+	mutex_lock(&ltc3562->mutex);
+
+	ret = status->shadow_data & ~(REGULATOR_ENABLE_BIT);
+
+	mutex_unlock(&ltc3562->mutex);
+
+	return ret;
+}
+
+static struct regulator_ops ltc3562_regulator_ops = {
+	.is_enabled = ltc3562_regulator_is_enabled,
+	.enable = ltc3562_regulator_enable,
+	.disable = ltc3562_regulator_disable,
+	.set_voltage_sel = ltc3562_set_voltage_sel,
+	.get_voltage_sel = ltc3562_get_voltage_sel,
+	.list_voltage = regulator_list_voltage_linear,
+	.map_voltage = regulator_map_voltage_linear,
+};
+
+static struct regulator_desc ltc3562_regulators[] = {
+	{
+		.name = "R400B",
+		.id = LTC3562_R400B_ID,
+		.ops = &ltc3562_regulator_ops,
+		.min_uV = REGULATOR_TYPE_B_MIN_UV,
+		.uV_step = REGULATOR_TYPE_B_UV_STEP,
+		.n_voltages = REGULATOR_TYPE_B_NUM_VOLTAGES,
+		.type = REGULATOR_VOLTAGE,
+		.owner = THIS_MODULE,
+	},
+	{
+		.name = "R600B",
+		.id = LTC3562_R600B_ID,
+		.ops = &ltc3562_regulator_ops,
+		.min_uV = REGULATOR_TYPE_B_MIN_UV,
+		.uV_step = REGULATOR_TYPE_B_UV_STEP,
+		.n_voltages = REGULATOR_TYPE_B_NUM_VOLTAGES,
+		.type = REGULATOR_VOLTAGE,
+		.owner = THIS_MODULE,
+	},
+	{
+		.name = "R400A",
+		.id = LTC3562_R400A_ID,
+		.ops = &ltc3562_regulator_ops,
+		.min_uV = REGULATOR_TYPE_A_MIN_UV,
+		.uV_step = REGULATOR_TYPE_A_UV_STEP,
+		.n_voltages = REGULATOR_TYPE_A_NUM_VOLTAGES,
+		.type = REGULATOR_VOLTAGE,
+		.owner = THIS_MODULE,
+	},
+	{
+		.name = "R600A",
+		.id = LTC3562_R600A_ID,
+		.ops = &ltc3562_regulator_ops,
+		.min_uV = REGULATOR_TYPE_A_MIN_UV,
+		.uV_step = REGULATOR_TYPE_A_UV_STEP,
+		.n_voltages = REGULATOR_TYPE_A_NUM_VOLTAGES,
+		.type = REGULATOR_VOLTAGE,
+		.owner = THIS_MODULE,
+	},
+};
+
+
+static int ltc3562_write(struct i2c_client *i2c, u8 reg_a, u8 reg_b)
+{
+	return i2c_smbus_write_byte_data(i2c, reg_a, reg_b);
+}
+
+/* Write dummy data to detect presence of physical device */
+static int ltc3562_dummy_write(struct i2c_client *i2c)
+{
+	return ltc3562_write(i2c, 0, 0);
+}
+
+
+static int ltc3562_regulators_unregister(struct ltc3562 *ltc3562,
+	int num_regulators)
+{
+	while (--num_regulators >= 0) {
+		pr_debug("Unregistering regulator: %s\n",
+			ltc3562->rdev[num_regulators]->desc->name);
+		regulator_unregister(ltc3562->rdev[num_regulators]);
+	}
+	return 0;
+}
+
+static int ltc3562_i2c_probe(struct i2c_client *i2c,
+	const struct i2c_device_id *id)
+{
+	int i, error;
+	unsigned int r1, r2;
+	unsigned long uV;
+	struct ltc3562 *ltc3562;
+	struct regulator_config rconfig = { };
+	struct device_node *np_regulators, *np;
+	struct device_node *np_child;
+
+	ltc3562 = devm_kzalloc(&i2c->dev,
+		sizeof(struct ltc3562), GFP_KERNEL);
+	if (ltc3562 == NULL)
+		return -ENOMEM;
+
+	ltc3562->i2c = i2c;
+
+	mutex_init(&ltc3562->mutex);
+
+	if (ltc3562_dummy_write(i2c) < 0) {
+		dev_err(&i2c->dev,
+			"Could not find device LTC3562 on i2c bus\n");
+		error = -ENODEV;
+		goto lbl_exit;
+	}
+
+	np = of_node_get(i2c->dev.of_node);
+	np_regulators = of_get_child_by_name(np, "regulators");
+
+	if (np_regulators == NULL) {
+		dev_err(&i2c->dev, "Could not find regulators node\n");
+		error = -EINVAL;
+		goto lbl_exit;
+	}
+
+	for (i = 0; i < LTC3562_NUM_REGULATORS; ++i) {
+		np_child = of_get_child_by_name(np_regulators,
+			ltc3562_regulators[i].name);
+		if (np_child == NULL) {
+			dev_err(&i2c->dev,
+				"Could not find regulator data for %s in devicetree\n",
+				ltc3562_regulators[i].name);
+			error = -EINVAL;
+			goto lbl_cleanup;
+		}
+
+		if ((ltc3562_regulators[i].id == LTC3562_R400A_ID) ||
+			(ltc3562_regulators[i].id == LTC3562_R600A_ID)) {
+			/* If regulator is A type get resistor values */
+			error = of_property_read_u32(np_child,
+				"ltc3562-A-r1", &r1);
+			if (error) {
+				dev_err(&i2c->dev,
+					"Resistor value ltc3562-A-r1 for A-Type regulator %s not defined\n",
+					ltc3562_regulators[i].name);
+				goto lbl_cleanup;
+			}
+
+			error = of_property_read_u32(np_child,
+				"ltc3562-A-r2", &r2);
+			if (error) {
+				dev_err(&i2c->dev,
+					"Resistor value ltc3562-A-r2 for A-Type regulator %s not defined\n",
+					ltc3562_regulators[i].name);
+				goto lbl_cleanup;
+			}
+			uV = ltc3562_regulators[i].min_uV / 1000;
+			ltc3562_regulators[i].min_uV =
+				(uV + mult_frac(uV, r1, r2)) * 1000;
+
+			uV = ltc3562_regulators[i].uV_step / 1000;
+			ltc3562_regulators[i].uV_step =
+				(uV + mult_frac(uV, r1, r2)) * 1000;
+		}
+
+		rconfig.dev = &i2c->dev;
+		rconfig.init_data =
+			of_get_regulator_init_data(&i2c->dev, np_child);
+		rconfig.driver_data = ltc3562;
+		rconfig.of_node = np_child;
+
+		ltc3562->rstatus[i].voltage_set = 0;
+
+		ltc3562->rdev[i] =
+			regulator_register(&ltc3562_regulators[i], &rconfig);
+
+		if (IS_ERR(ltc3562->rdev[i])) {
+			error = PTR_ERR(ltc3562->rdev[i]);
+			dev_err(&i2c->dev,
+				"could not register regulator, Error %d\n",
+				error);
+			goto lbl_cleanup;
+		}
+	}
+
+	i2c_set_clientdata(i2c, ltc3562);
+	dev_dbg(&i2c->dev, "LTC3562 Driver loaded.\n");
+	return 0;
+
+lbl_cleanup:
+	ltc3562_regulators_unregister(ltc3562, i);
+lbl_exit:
+	return error;
+}
+
+static int ltc3562_i2c_remove(struct i2c_client *i2c)
+{
+	struct ltc3562 *ltc3562 = i2c_get_clientdata(i2c);
+
+	ltc3562_regulators_unregister(ltc3562, LTC3562_NUM_REGULATORS);
+
+	return 0;
+}
+
+static const struct i2c_device_id ltc3562_i2c_id[] = {
+	{ "ltc3562", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ltc3562_i2c_id);
+
+static struct i2c_driver ltc3562_i2c_driver = {
+	.driver = {
+		.name = "LTC3562",
+		.owner = THIS_MODULE,
+	},
+	.probe    = ltc3562_i2c_probe,
+	.remove   = ltc3562_i2c_remove,
+	.id_table = ltc3562_i2c_id,
+};
+
+module_i2c_driver(ltc3562_i2c_driver);
+
+MODULE_DESCRIPTION("LTC3562 Regulator Driver");
+MODULE_AUTHOR("auryn.verwegen@topic.nl");
+MODULE_AUTHOR("mike.looijmans@topic.nl");
+MODULE_LICENSE("GPL v2");
-- 
1.7.9.5