regulator: Add LTC3676 support

This patch adds support for the Linear Technology LTC3676
8-output I2C voltage regulator IC.

Cc: Jaffer Kapasi <[e-mail]>
Signed-off-by: Tim Harvey <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

Documentation/devicetree/bindings/regulator/ltc3676.txt

···
+Linear Technology LTC3676 8-output regulators
+
+Required properties:
+- compatible: "lltc,ltc3676"
+- reg: I2C slave address
+
+Required child node:
+- regulators: Contains eight regulator child nodes sw1, sw2, sw3, sw4,
+  ldo1, ldo2, ldo3, and ldo4, specifying the initialization data as
+  documented in Documentation/devicetree/bindings/regulator/regulator.txt.
+
+Each regulator is defined using the standard binding for regulators. The
+nodes for sw1, sw2, sw3, sw4, ldo1, ldo2 and ldo4 additionally need to specify
+the resistor values of their external feedback voltage dividers:
+
+Required properties (not on ldo3):
+- lltc,fb-voltage-divider: An array of two integers containing the resistor
+  values R1 and R2 of the feedback voltage divider in ohms.
+
+Regulators sw1, sw2, sw3, sw4 can regulate the feedback reference from:
+412.5mV to 800mV in 12.5 mV steps. The output voltage thus ranges between
+0.4125 * (1 + R1/R2) V and 0.8 * (1 + R1/R2) V.
+
+Regulators ldo1, ldo2, and ldo4 have a fixed 0.725 V reference and thus output
+0.725 * (1 + R1/R2) V. The ldo3 regulator is fixed to 1.8 V.  The ldo1 standby
+regulator can not be disabled and thus should have the regulator-always-on
+property set.
+
+Example:
+
+	ltc3676: pmic@3c {
+		compatible = "lltc,ltc3676";
+		reg = <0x3c>;
+
+		regulators {
+			sw1_reg: sw1 {
+				regulator-min-microvolt = <674400>;
+				regulator-max-microvolt = <1308000>;
+				lltc,fb-voltage-divider = <127000 200000>;
+				regulator-ramp-delay = <7000>;
+				regulator-boot-on;
+				regulator-always-on;
+			};
+
+			sw2_reg: sw2 {
+				regulator-min-microvolt = <1033310>;
+				regulator-max-microvolt = <200400>;
+				lltc,fb-voltage-divider = <301000 200000>;
+				regulator-ramp-delay = <7000>;
+				regulator-boot-on;
+				regulator-always-on;
+			};
+
+			sw3_reg: sw3 {
+				regulator-min-microvolt = <674400>;
+				regulator-max-microvolt = <130800>;
+				lltc,fb-voltage-divider = <127000 200000>;
+				regulator-ramp-delay = <7000>;
+				regulator-boot-on;
+				regulator-always-on;
+			};
+
+			sw4_reg: sw4 {
+				regulator-min-microvolt = <868310>;
+				regulator-max-microvolt = <168400>;
+				lltc,fb-voltage-divider = <221000 200000>;
+				regulator-ramp-delay = <7000>;
+				regulator-boot-on;
+				regulator-always-on;
+			};
+
+			ldo2_reg: ldo2 {
+				regulator-min-microvolt = <2490375>;
+				regulator-max-microvolt = <2490375>;
+				lltc,fb-voltage-divider = <487000 200000>;
+				regulator-boot-on;
+				regulator-always-on;
+			};
+
+			ldo3_reg: ldo3 {
+				regulator-min-microvolt = <1800000>;
+				regulator-max-microvolt = <1800000>;
+				regulator-boot-on;
+			};
+
+			ldo4_reg: ldo4 {
+				regulator-min-microvolt = <3023250>;
+				regulator-max-microvolt = <3023250>;
+				lltc,fb-voltage-divider = <634000 200000>;
+				regulator-boot-on;
+				regulator-always-on;
+			};
+		};
+	};

drivers/regulator/Kconfig

···
 	  This enables support for the LTC3589, LTC3589-1, and LTC3589-2
 	  8-output regulators controlled via I2C.
 
+config REGULATOR_LTC3676
+	tristate "LTC3676 8-output voltage regulator"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  This enables support for the LTC3676
+	  8-output regulators controlled via I2C.
+
 config REGULATOR_MAX14577
 	tristate "Maxim 14577/77836 regulator"
 	depends on MFD_MAX14577

drivers/regulator/Makefile

···
 obj-$(CONFIG_REGULATOR_LP8788) += lp8788-ldo.o
 obj-$(CONFIG_REGULATOR_LP8755) += lp8755.o
 obj-$(CONFIG_REGULATOR_LTC3589) += ltc3589.o
+obj-$(CONFIG_REGULATOR_LTC3676) += ltc3676.o
 obj-$(CONFIG_REGULATOR_MAX14577) += max14577-regulator.o
 obj-$(CONFIG_REGULATOR_MAX1586) += max1586.o
 obj-$(CONFIG_REGULATOR_MAX77620) += max77620-regulator.o

drivers/regulator/ltc3676.c

···
+/*
+ * Copyright (C) 2016 Gateworks Corporation, Inc. All Rights Reserved.
+ *
+ * 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.
+ *
+ * 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.
+ *
+ */
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+#include <linux/regulator/of_regulator.h>
+
+#define DRIVER_NAME		"ltc3676"
+
+/* LTC3676 Registers */
+#define LTC3676_BUCK1     0x01
+#define LTC3676_BUCK2     0x02
+#define LTC3676_BUCK3     0x03
+#define LTC3676_BUCK4     0x04
+#define LTC3676_LDOA      0x05
+#define LTC3676_LDOB      0x06
+#define LTC3676_SQD1      0x07
+#define LTC3676_SQD2      0x08
+#define LTC3676_CNTRL     0x09
+#define LTC3676_DVB1A     0x0A
+#define LTC3676_DVB1B     0x0B
+#define LTC3676_DVB2A     0x0C
+#define LTC3676_DVB2B     0x0D
+#define LTC3676_DVB3A     0x0E
+#define LTC3676_DVB3B     0x0F
+#define LTC3676_DVB4A     0x10
+#define LTC3676_DVB4B     0x11
+#define LTC3676_MSKIRQ    0x12
+#define LTC3676_MSKPG     0x13
+#define LTC3676_USER      0x14
+#define LTC3676_IRQSTAT   0x15
+#define LTC3676_PGSTATL   0x16
+#define LTC3676_PGSTATRT  0x17
+#define LTC3676_HRST      0x1E
+#define LTC3676_CLIRQ     0x1F
+
+#define LTC3676_DVBxA_REF_SELECT	BIT(5)
+
+#define LTC3676_IRQSTAT_PGOOD_TIMEOUT	BIT(3)
+#define LTC3676_IRQSTAT_UNDERVOLT_WARN	BIT(4)
+#define LTC3676_IRQSTAT_UNDERVOLT_FAULT	BIT(5)
+#define LTC3676_IRQSTAT_THERMAL_WARN	BIT(6)
+#define LTC3676_IRQSTAT_THERMAL_FAULT	BIT(7)
+
+enum ltc3676_reg {
+	LTC3676_SW1,
+	LTC3676_SW2,
+	LTC3676_SW3,
+	LTC3676_SW4,
+	LTC3676_LDO1,
+	LTC3676_LDO2,
+	LTC3676_LDO3,
+	LTC3676_LDO4,
+	LTC3676_NUM_REGULATORS,
+};
+
+struct ltc3676 {
+	struct regmap *regmap;
+	struct device *dev;
+	struct regulator_desc regulator_descs[LTC3676_NUM_REGULATORS];
+	struct regulator_dev *regulators[LTC3676_NUM_REGULATORS];
+};
+
+static int ltc3676_set_suspend_voltage(struct regulator_dev *rdev, int uV)
+{
+	struct ltc3676 *ltc3676 = rdev_get_drvdata(rdev);
+	struct device *dev = ltc3676->dev;
+	int dcdc = rdev_get_id(rdev);
+	int sel;
+
+	dev_dbg(dev, "%s id=%d uV=%d\n", __func__, dcdc, uV);
+	sel = regulator_map_voltage_linear(rdev, uV, uV);
+	if (sel < 0)
+		return sel;
+
+	/* DVBB register follows right after the corresponding DVBA register */
+	return regmap_update_bits(ltc3676->regmap, rdev->desc->vsel_reg + 1,
+				  rdev->desc->vsel_mask, sel);
+}
+
+static int ltc3676_set_suspend_mode(struct regulator_dev *rdev,
+				    unsigned int mode)
+{
+	struct ltc3676 *ltc3676= rdev_get_drvdata(rdev);
+	struct device *dev = ltc3676->dev;
+	int mask, val;
+	int dcdc = rdev_get_id(rdev);
+
+	dev_dbg(dev, "%s id=%d mode=%d\n", __func__, dcdc, mode);
+
+	mask = LTC3676_DVBxA_REF_SELECT;
+	switch (mode) {
+	case REGULATOR_MODE_STANDBY:
+		val = 0; /* select DVBxA */
+		break;
+	case REGULATOR_MODE_NORMAL:
+		val = LTC3676_DVBxA_REF_SELECT; /* select DVBxB */
+		break;
+	default:
+		dev_warn(&rdev->dev, "%s: regulator mode: 0x%x not supported\n",
+			 rdev->desc->name, mode);
+		return -EINVAL;
+	}
+
+	return regmap_update_bits(ltc3676->regmap, rdev->desc->vsel_reg,
+				  mask, val);
+}
+
+static inline unsigned int ltc3676_scale(unsigned int uV, u32 r1, u32 r2)
+{
+	uint64_t tmp;
+	if (uV == 0)
+		return 0;
+	tmp = (uint64_t)uV * r1;
+	do_div(tmp, r2);
+	return uV + (unsigned int)tmp;
+}
+
+static int ltc3676_of_parse_cb(struct device_node *np,
+			       const struct regulator_desc *desc,
+			       struct regulator_config *config)
+{
+	struct ltc3676 *ltc3676 = config->driver_data;
+	struct regulator_desc *rdesc = &ltc3676->regulator_descs[desc->id];
+	u32 r[2];
+	int ret;
+
+	/* LDO3 has a fixed output */
+	if (desc->id == LTC3676_LDO3)
+		return 0;
+
+	ret = of_property_read_u32_array(np, "lltc,fb-voltage-divider", r, 2);
+	if (ret) {
+		dev_err(ltc3676->dev, "Failed to parse voltage divider: %d\n",
+			ret);
+		return ret;
+	}
+
+	rdesc->min_uV = ltc3676_scale(desc->min_uV, r[0], r[1]);
+	rdesc->uV_step = ltc3676_scale(desc->uV_step, r[0], r[1]);
+	rdesc->fixed_uV = ltc3676_scale(desc->fixed_uV, r[0], r[1]);
+
+	return 0;
+}
+
+/* SW1, SW2, SW3, SW4 linear 0.8V-3.3V with scalar via R1/R2 feeback res */
+static struct regulator_ops ltc3676_linear_regulator_ops = {
+	.enable = regulator_enable_regmap,
+	.disable = regulator_disable_regmap,
+	.is_enabled = regulator_is_enabled_regmap,
+	.list_voltage = regulator_list_voltage_linear,
+	.set_voltage_sel = regulator_set_voltage_sel_regmap,
+	.get_voltage_sel = regulator_get_voltage_sel_regmap,
+	.set_suspend_voltage = ltc3676_set_suspend_voltage,
+	.set_suspend_mode = ltc3676_set_suspend_mode,
+};
+
+/* LDO1 always on fixed 0.8V-3.3V via scalar via R1/R2 feeback res */
+static struct regulator_ops ltc3676_fixed_standby_regulator_ops = {
+};
+
+/* LDO2, LDO3 fixed (LDO2 has external scalar via R1/R2 feedback res) */
+static struct regulator_ops ltc3676_fixed_regulator_ops = {
+	.enable = regulator_enable_regmap,
+	.disable = regulator_disable_regmap,
+	.is_enabled = regulator_is_enabled_regmap,
+};
+
+#define LTC3676_REG(_id, _name, _ops, en_reg, en_bit, dvba_reg, dvb_mask)   \
+	[LTC3676_ ## _id] = {                                        \
+		.name = #_name,                                \
+		.of_match = of_match_ptr(#_name),              \
+		.regulators_node = of_match_ptr("regulators"), \
+		.of_parse_cb = ltc3676_of_parse_cb,            \
+		.n_voltages = (dvb_mask) + 1,                  \
+		.min_uV = (dvba_reg) ? 412500 : 0,             \
+		.uV_step = (dvba_reg) ? 12500 : 0,             \
+		.ramp_delay = (dvba_reg) ? 800 : 0,            \
+		.fixed_uV = (dvb_mask) ? 0 : 725000,           \
+		.ops = &ltc3676_ ## _ops ## _regulator_ops,    \
+		.type = REGULATOR_VOLTAGE,                     \
+		.id = LTC3676_ ## _id,                         \
+		.owner = THIS_MODULE,                          \
+		.vsel_reg = (dvba_reg),                        \
+		.vsel_mask = (dvb_mask),                       \
+		.enable_reg = (en_reg),                        \
+		.enable_mask = (1 << en_bit),                  \
+	}
+
+#define LTC3676_LINEAR_REG(_id, _name, _en, _dvba)                     \
+	LTC3676_REG(_id, _name, linear,                                \
+		    LTC3676_ ## _en, 7,                                \
+		    LTC3676_ ## _dvba, 0x1f)
+
+#define LTC3676_FIXED_REG(_id, _name, _en_reg, _en_bit)                \
+	LTC3676_REG(_id, _name, fixed, LTC3676_ ## _en_reg, _en_bit, 0, 0)
+
+static struct regulator_desc ltc3676_regulators[LTC3676_NUM_REGULATORS] = {
+	LTC3676_LINEAR_REG(SW1, sw1, BUCK1, DVB1A),
+	LTC3676_LINEAR_REG(SW2, sw2, BUCK2, DVB2A),
+	LTC3676_LINEAR_REG(SW3, sw3, BUCK3, DVB3A),
+	LTC3676_LINEAR_REG(SW4, sw4, BUCK4, DVB4A),
+	LTC3676_REG(LDO1, ldo1, fixed_standby, 0, 0, 0, 0),
+	LTC3676_FIXED_REG(LDO2, ldo2, LDOA, 2),
+	LTC3676_FIXED_REG(LDO3, ldo3, LDOA, 5),
+	LTC3676_FIXED_REG(LDO4, ldo4, LDOB, 2),
+};
+
+static bool ltc3676_writeable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case LTC3676_IRQSTAT:
+	case LTC3676_BUCK1:
+	case LTC3676_BUCK2:
+	case LTC3676_BUCK3:
+	case LTC3676_BUCK4:
+	case LTC3676_LDOA:
+	case LTC3676_LDOB:
+	case LTC3676_SQD1:
+	case LTC3676_SQD2:
+	case LTC3676_CNTRL:
+	case LTC3676_DVB1A:
+	case LTC3676_DVB1B:
+	case LTC3676_DVB2A:
+	case LTC3676_DVB2B:
+	case LTC3676_DVB3A:
+	case LTC3676_DVB3B:
+	case LTC3676_DVB4A:
+	case LTC3676_DVB4B:
+	case LTC3676_MSKIRQ:
+	case LTC3676_MSKPG:
+	case LTC3676_USER:
+	case LTC3676_HRST:
+	case LTC3676_CLIRQ:
+		return true;
+	}
+	return false;
+}
+
+static bool ltc3676_readable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case LTC3676_IRQSTAT:
+	case LTC3676_BUCK1:
+	case LTC3676_BUCK2:
+	case LTC3676_BUCK3:
+	case LTC3676_BUCK4:
+	case LTC3676_LDOA:
+	case LTC3676_LDOB:
+	case LTC3676_SQD1:
+	case LTC3676_SQD2:
+	case LTC3676_CNTRL:
+	case LTC3676_DVB1A:
+	case LTC3676_DVB1B:
+	case LTC3676_DVB2A:
+	case LTC3676_DVB2B:
+	case LTC3676_DVB3A:
+	case LTC3676_DVB3B:
+	case LTC3676_DVB4A:
+	case LTC3676_DVB4B:
+	case LTC3676_MSKIRQ:
+	case LTC3676_MSKPG:
+	case LTC3676_USER:
+	case LTC3676_HRST:
+	case LTC3676_CLIRQ:
+		return true;
+	}
+	return false;
+}
+
+static bool ltc3676_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case LTC3676_IRQSTAT:
+	case LTC3676_PGSTATL:
+	case LTC3676_PGSTATRT:
+		return true;
+	}
+	return false;
+}
+
+static const struct regmap_config ltc3676_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.writeable_reg = ltc3676_writeable_reg,
+	.readable_reg = ltc3676_readable_reg,
+	.volatile_reg = ltc3676_volatile_reg,
+	.max_register = LTC3676_CLIRQ,
+	.use_single_rw = true,
+	.cache_type = REGCACHE_RBTREE,
+};
+
+static irqreturn_t ltc3676_isr(int irq, void *dev_id)
+{
+	struct ltc3676 *ltc3676 = dev_id;
+	struct device *dev = ltc3676->dev;
+	unsigned int i, irqstat, event;
+
+	regmap_read(ltc3676->regmap, LTC3676_IRQSTAT, &irqstat);
+
+	dev_dbg(dev, "irq%d irqstat=0x%02x\n", irq, irqstat);
+	if (irqstat & LTC3676_IRQSTAT_THERMAL_WARN) {
+		dev_warn(dev, "Over-temperature Warning\n");
+		event = REGULATOR_EVENT_OVER_TEMP;
+		for (i = 0; i < LTC3676_NUM_REGULATORS; i++)
+			regulator_notifier_call_chain(ltc3676->regulators[i],
+						      event, NULL);
+	}
+
+	if (irqstat & LTC3676_IRQSTAT_UNDERVOLT_WARN) {
+		dev_info(dev, "Undervoltage Warning\n");
+		event = REGULATOR_EVENT_UNDER_VOLTAGE;
+		for (i = 0; i < LTC3676_NUM_REGULATORS; i++)
+			regulator_notifier_call_chain(ltc3676->regulators[i],
+						      event, NULL);
+	}
+
+	/* Clear warning condition */
+	regmap_write(ltc3676->regmap, LTC3676_CLIRQ, 0);
+
+	return IRQ_HANDLED;
+}
+
+static int ltc3676_regulator_probe(struct i2c_client *client,
+				    const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	struct regulator_init_data *init_data = dev_get_platdata(dev);
+	struct regulator_desc *descs;
+	struct ltc3676 *ltc3676;
+	int i, ret;
+
+	ltc3676 = devm_kzalloc(dev, sizeof(*ltc3676), GFP_KERNEL);
+	if (!ltc3676)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, ltc3676);
+	ltc3676->dev = dev;
+
+	descs = ltc3676->regulator_descs;
+	memcpy(descs, ltc3676_regulators, sizeof(ltc3676_regulators));
+	descs[LTC3676_LDO3].fixed_uV = 1800000; /* LDO3 is fixed 1.8V */
+
+	ltc3676->regmap = devm_regmap_init_i2c(client, &ltc3676_regmap_config);
+	if (IS_ERR(ltc3676->regmap)) {
+		ret = PTR_ERR(ltc3676->regmap);
+		dev_err(dev, "failed to initialize regmap: %d\n", ret);
+		return ret;
+	}
+
+	for (i = 0; i < LTC3676_NUM_REGULATORS; i++) {
+		struct regulator_desc *desc = &ltc3676->regulator_descs[i];
+		struct regulator_config config = { };
+
+		if (init_data)
+			config.init_data = &init_data[i];
+
+		config.dev = dev;
+		config.driver_data = ltc3676;
+
+		ltc3676->regulators[i] = devm_regulator_register(dev, desc,
+								 &config);
+		if (IS_ERR(ltc3676->regulators[i])) {
+			ret = PTR_ERR(ltc3676->regulators[i]);
+			dev_err(dev, "failed to register regulator %s: %d\n",
+				desc->name, ret);
+			return ret;
+		}
+	}
+
+	regmap_write(ltc3676->regmap, LTC3676_CLIRQ, 0);
+	if (client->irq) {
+		ret = devm_request_threaded_irq(dev, client->irq, NULL,
+						ltc3676_isr,
+						IRQF_TRIGGER_LOW | IRQF_ONESHOT,
+						client->name, ltc3676);
+		if (ret) {
+			dev_err(dev, "Failed to request IRQ: %d\n", ret);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static const struct i2c_device_id ltc3676_i2c_id[] = {
+	{ "ltc3676" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ltc3676_i2c_id);
+
+static struct i2c_driver ltc3676_driver = {
+	.driver = {
+		.name = DRIVER_NAME,
+	},
+	.probe = ltc3676_regulator_probe,
+	.id_table = ltc3676_i2c_id,
+};
+module_i2c_driver(ltc3676_driver);
+
+MODULE_AUTHOR("Tim Harvey <[e-mail]>");
+MODULE_DESCRIPTION("Regulator driver for Linear Technology LTC1376");
+MODULE_LICENSE("GPL v2");