regulator: max8973: add regulator driver support

The MAXIM MAX8973 high-efficiency, three phase, DC-DC step-down
switching regulator delievers up to 9A of output current. Each
phase operates at a 2MHz fixed frequency with a 120 deg shift
from the adjacent phase, allowing the use of small magnetic
component.

Add regulator driver for this device.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

3 files changed, 516 insertions, 0 deletions

diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 67d47b59a66d..2b8031235125 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -204,6 +204,16 @@ config REGULATOR_MAX8952
           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_MAX8973
+        tristate "Maxim MAX8973 voltage regulator "
+        depends on I2C
+        select REGMAP_I2C
+        help
+          The MAXIM MAX8973 high-efficiency. three phase, DC-DC step-down
+          switching regulator delievers up to 9A of output current. Each
+          phase operates at a 2MHz fixed frequency with a 120 deg shift
+          from the adjacent phase, allowing the use of small magnetic component.
+
 config REGULATOR_MAX8997
         tristate "Maxim 8997/8966 regulator"
         depends on MFD_MAX8997
diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
index e431eed8a878..3b51e0de33da 100644
--- a/drivers/regulator/Makefile
+++ b/drivers/regulator/Makefile
@@ -34,6 +34,7 @@ obj-$(CONFIG_REGULATOR_MAX8660) += max8660.o
 obj-$(CONFIG_REGULATOR_MAX8907) += max8907-regulator.o
 obj-$(CONFIG_REGULATOR_MAX8925) += max8925-regulator.o
 obj-$(CONFIG_REGULATOR_MAX8952) += max8952.o
+obj-$(CONFIG_REGULATOR_MAX8973) += max8973-regulator.o
 obj-$(CONFIG_REGULATOR_MAX8997) += max8997.o
 obj-$(CONFIG_REGULATOR_MAX8998) += max8998.o
 obj-$(CONFIG_REGULATOR_MAX77686) += max77686.o
diff --git a/drivers/regulator/max8973-regulator.c b/drivers/regulator/max8973-regulator.c
new file mode 100644
index 000000000000..e6328f935767
--- /dev/null
+++ b/drivers/regulator/max8973-regulator.c
@@ -0,0 +1,505 @@
+/*
+ * max8973-regulator.c -- Maxim max8973
+ *
+ * Regulator driver for MAXIM 8973 DC-DC step-down switching regulator.
+ *
+ * Copyright (c) 2012, NVIDIA Corporation.
+ *
+ * Author: Laxman Dewangan <ldewangan@nvidia.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 version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any kind,
+ * whether express or implied; 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/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+#include <linux/regulator/max8973-regulator.h>
+#include <linux/gpio.h>
+#include <linux/i2c.h>
+#include <linux/slab.h>
+#include <linux/regmap.h>
+
+/* Register definitions */
+#define MAX8973_VOUT                                    0x0
+#define MAX8973_VOUT_DVS                                0x1
+#define MAX8973_CONTROL1                                0x2
+#define MAX8973_CONTROL2                                0x3
+#define MAX8973_CHIPID1                                 0x4
+#define MAX8973_CHIPID2                                 0x5
+
+#define MAX8973_MAX_VOUT_REG                            2
+
+/* MAX8973_VOUT */
+#define MAX8973_VOUT_ENABLE                             BIT(7)
+#define MAX8973_VOUT_MASK                               0x7F
+
+/* MAX8973_VOUT_DVS */
+#define MAX8973_DVS_VOUT_MASK                           0x7F
+
+/* MAX8973_CONTROL1 */
+#define MAX8973_SNS_ENABLE                              BIT(7)
+#define MAX8973_FPWM_EN_M                               BIT(6)
+#define MAX8973_NFSR_ENABLE                             BIT(5)
+#define MAX8973_AD_ENABLE                               BIT(4)
+#define MAX8973_BIAS_ENABLE                             BIT(3)
+#define MAX8973_FREQSHIFT_9PER                          BIT(2)
+
+#define MAX8973_RAMP_12mV_PER_US                        0x0
+#define MAX8973_RAMP_25mV_PER_US                        0x1
+#define MAX8973_RAMP_50mV_PER_US                        0x2
+#define MAX8973_RAMP_200mV_PER_US                       0x3
+
+/* MAX8973_CONTROL2 */
+#define MAX8973_WDTMR_ENABLE                            BIT(6)
+#define MAX8973_DISCH_ENBABLE                           BIT(5)
+#define MAX8973_FT_ENABLE                               BIT(4)
+
+#define MAX8973_CKKADV_TRIP_DISABLE                     0xC
+#define MAX8973_CKKADV_TRIP_75mV_PER_US                 0x0
+#define MAX8973_CKKADV_TRIP_150mV_PER_US                0x4
+#define MAX8973_CKKADV_TRIP_75mV_PER_US_HIST_DIS        0x8
+#define MAX8973_CONTROL_CLKADV_TRIP_MASK                0x00030000
+
+#define MAX8973_INDUCTOR_MIN_30_PER                     0x0
+#define MAX8973_INDUCTOR_NOMINAL                        0x1
+#define MAX8973_INDUCTOR_PLUS_30_PER                    0x2
+#define MAX8973_INDUCTOR_PLUS_60_PER                    0x3
+#define MAX8973_CONTROL_INDUCTOR_VALUE_MASK             0x00300000
+
+#define MAX8973_MIN_VOLATGE                             606250
+#define MAX8973_MAX_VOLATGE                             1400000
+#define MAX8973_VOLATGE_STEP                            6250
+#define MAX8973_BUCK_N_VOLTAGE                          0x80
+
+/* Maxim 8973 chip information */
+struct max8973_chip {
+        struct device *dev;
+        struct regulator_desc desc;
+        struct regulator_dev *rdev;
+        struct regmap *regmap;
+        bool enable_external_control;
+        int dvs_gpio;
+        int lru_index[MAX8973_MAX_VOUT_REG];
+        int curr_vout_val[MAX8973_MAX_VOUT_REG];
+        int curr_vout_reg;
+        int curr_gpio_val;
+        bool valid_dvs_gpio;
+};
+
+/*
+ * find_voltage_set_register: Find new voltage configuration register (VOUT).
+ * The finding of the new VOUT register will be based on the LRU mechanism.
+ * Each VOUT register will have different voltage configured . This
+ * Function will look if any of the VOUT register have requested voltage set
+ * or not.
+ *     - If it is already there then it will make that register as most
+ *       recently used and return as found so that caller need not to set
+ *       the VOUT register but need to set the proper gpios to select this
+ *       VOUT register.
+ *     - If requested voltage is not found then it will use the least
+ *       recently mechanism to get new VOUT register for new configuration
+ *       and will return not_found so that caller need to set new VOUT
+ *       register and then gpios (both).
+ */
+static bool find_voltage_set_register(struct max8973_chip *tps,
+                int req_vsel, int *vout_reg, int *gpio_val)
+{
+        int i;
+        bool found = false;
+        int new_vout_reg = tps->lru_index[MAX8973_MAX_VOUT_REG - 1];
+        int found_index = MAX8973_MAX_VOUT_REG - 1;
+
+        for (i = 0; i < MAX8973_MAX_VOUT_REG; ++i) {
+                if (tps->curr_vout_val[tps->lru_index[i]] == req_vsel) {
+                        new_vout_reg = tps->lru_index[i];
+                        found_index = i;
+                        found = true;
+                        goto update_lru_index;
+                }
+        }
+
+update_lru_index:
+        for (i = found_index; i > 0; i--)
+                tps->lru_index[i] = tps->lru_index[i - 1];
+
+        tps->lru_index[0] = new_vout_reg;
+        *gpio_val = new_vout_reg;
+        *vout_reg = MAX8973_VOUT + new_vout_reg;
+        return found;
+}
+
+static int max8973_dcdc_get_voltage_sel(struct regulator_dev *rdev)
+{
+        struct max8973_chip *max = rdev_get_drvdata(rdev);
+        unsigned int data;
+        int ret;
+
+        ret = regmap_read(max->regmap, max->curr_vout_reg, &data);
+        if (ret < 0) {
+                dev_err(max->dev, "register %d read failed, err = %d\n",
+                        max->curr_vout_reg, ret);
+                return ret;
+        }
+        return data & MAX8973_VOUT_MASK;
+}
+
+static int max8973_dcdc_set_voltage_sel(struct regulator_dev *rdev,
+             unsigned vsel)
+{
+        struct max8973_chip *max = rdev_get_drvdata(rdev);
+        int ret;
+        bool found = false;
+        int vout_reg = max->curr_vout_reg;
+        int gpio_val = max->curr_gpio_val;
+
+        /*
+         * If gpios are available to select the VOUT register then least
+         * recently used register for new configuration.
+         */
+        if (max->valid_dvs_gpio)
+                found = find_voltage_set_register(max, vsel,
+                                        &vout_reg, &gpio_val);
+
+        if (!found) {
+                ret = regmap_update_bits(max->regmap, vout_reg,
+                                        MAX8973_VOUT_MASK, vsel);
+                if (ret < 0) {
+                        dev_err(max->dev, "register %d update failed, err %d\n",
+                                 vout_reg, ret);
+                        return ret;
+                }
+                max->curr_vout_reg = vout_reg;
+                max->curr_vout_val[gpio_val] = vsel;
+        }
+
+        /* Select proper VOUT register vio gpios */
+        if (max->valid_dvs_gpio) {
+                gpio_set_value_cansleep(max->dvs_gpio, gpio_val & 0x1);
+                max->curr_gpio_val = gpio_val;
+        }
+        return 0;
+}
+
+static int max8973_dcdc_set_mode(struct regulator_dev *rdev, unsigned int mode)
+{
+        struct max8973_chip *max = rdev_get_drvdata(rdev);
+        int ret;
+        int pwm;
+
+        /* Enable force PWM mode in FAST mode only. */
+        switch (mode) {
+        case REGULATOR_MODE_FAST:
+                pwm = MAX8973_FPWM_EN_M;
+                break;
+
+        case REGULATOR_MODE_NORMAL:
+                pwm = 0;
+                break;
+
+        default:
+                return -EINVAL;
+        }
+
+        ret = regmap_update_bits(max->regmap, MAX8973_CONTROL1,
+                                MAX8973_FPWM_EN_M, pwm);
+        if (ret < 0)
+                dev_err(max->dev, "register %d update failed, err %d\n",
+                                MAX8973_CONTROL1, ret);
+        return ret;
+}
+
+static unsigned int max8973_dcdc_get_mode(struct regulator_dev *rdev)
+{
+        struct max8973_chip *max = rdev_get_drvdata(rdev);
+        unsigned int data;
+        int ret;
+
+        ret = regmap_read(max->regmap, MAX8973_CONTROL1, &data);
+        if (ret < 0) {
+                dev_err(max->dev, "register %d read failed, err %d\n",
+                                MAX8973_CONTROL1, ret);
+                return ret;
+        }
+        return (data & MAX8973_FPWM_EN_M) ?
+                REGULATOR_MODE_FAST : REGULATOR_MODE_NORMAL;
+}
+
+static struct regulator_ops max8973_dcdc_ops = {
+        .get_voltage_sel        = max8973_dcdc_get_voltage_sel,
+        .set_voltage_sel        = max8973_dcdc_set_voltage_sel,
+        .list_voltage           = regulator_list_voltage_linear,
+        .set_mode               = max8973_dcdc_set_mode,
+        .get_mode               = max8973_dcdc_get_mode,
+};
+
+static int __devinit max8973_init_dcdc(struct max8973_chip *max,
+                struct max8973_regulator_platform_data *pdata)
+{
+        int ret;
+        uint8_t control1 = 0;
+        uint8_t control2 = 0;
+
+        if (pdata->control_flags & MAX8973_CONTROL_REMOTE_SENSE_ENABLE)
+                control1 |= MAX8973_SNS_ENABLE;
+
+        if (!(pdata->control_flags & MAX8973_CONTROL_FALLING_SLEW_RATE_ENABLE))
+                control1 |= MAX8973_NFSR_ENABLE;
+
+        if (pdata->control_flags & MAX8973_CONTROL_OUTPUT_ACTIVE_DISCH_ENABLE)
+                control1 |= MAX8973_AD_ENABLE;
+
+        if (pdata->control_flags & MAX8973_CONTROL_BIAS_ENABLE)
+                control1 |= MAX8973_BIAS_ENABLE;
+
+        if (pdata->control_flags & MAX8973_CONTROL_FREQ_SHIFT_9PER_ENABLE)
+                control1 |= MAX8973_FREQSHIFT_9PER;
+
+        /* Set ramp delay */
+        if (pdata->reg_init_data &&
+                        pdata->reg_init_data->constraints.ramp_delay) {
+                if (pdata->reg_init_data->constraints.ramp_delay < 25000)
+                        control1 = MAX8973_RAMP_12mV_PER_US;
+                else if (pdata->reg_init_data->constraints.ramp_delay < 50000)
+                        control1 = MAX8973_RAMP_25mV_PER_US;
+                else if (pdata->reg_init_data->constraints.ramp_delay < 200000)
+                        control1 = MAX8973_RAMP_50mV_PER_US;
+                else
+                        control1 = MAX8973_RAMP_200mV_PER_US;
+        } else {
+                control1 = MAX8973_RAMP_12mV_PER_US;
+                max->desc.ramp_delay = 12500;
+        }
+
+        if (!(pdata->control_flags & MAX8973_CONTROL_PULL_DOWN_ENABLE))
+                control2 |= MAX8973_DISCH_ENBABLE;
+
+        /*  Clock advance trip configuration */
+        switch (pdata->control_flags & MAX8973_CONTROL_CLKADV_TRIP_MASK) {
+        case MAX8973_CONTROL_CLKADV_TRIP_DISABLED:
+                control2 |= MAX8973_CKKADV_TRIP_DISABLE;
+                break;
+
+        case MAX8973_CONTROL_CLKADV_TRIP_75mV_PER_US:
+                control2 |= MAX8973_CKKADV_TRIP_75mV_PER_US;
+                break;
+
+        case MAX8973_CONTROL_CLKADV_TRIP_150mV_PER_US:
+                control2 |= MAX8973_CKKADV_TRIP_150mV_PER_US;
+                break;
+
+        case MAX8973_CONTROL_CLKADV_TRIP_75mV_PER_US_HIST_DIS:
+                control2 |= MAX8973_CKKADV_TRIP_75mV_PER_US_HIST_DIS;
+                break;
+        }
+
+        /* Configure inductor value */
+        switch (pdata->control_flags & MAX8973_CONTROL_INDUCTOR_VALUE_MASK) {
+        case MAX8973_CONTROL_INDUCTOR_VALUE_NOMINAL:
+                control2 |= MAX8973_INDUCTOR_NOMINAL;
+                break;
+
+        case MAX8973_CONTROL_INDUCTOR_VALUE_MINUS_30_PER:
+                control2 |= MAX8973_INDUCTOR_MIN_30_PER;
+                break;
+
+        case MAX8973_CONTROL_INDUCTOR_VALUE_PLUS_30_PER:
+                control2 |= MAX8973_INDUCTOR_PLUS_30_PER;
+                break;
+
+        case MAX8973_CONTROL_INDUCTOR_VALUE_PLUS_60_PER:
+                control2 |= MAX8973_INDUCTOR_PLUS_60_PER;
+                break;
+        }
+
+        ret = regmap_write(max->regmap, MAX8973_CONTROL1, control1);
+        if (ret < 0) {
+                dev_err(max->dev, "register %d write failed, err = %d",
+                                MAX8973_CONTROL1, ret);
+                return ret;
+        }
+
+        ret = regmap_write(max->regmap, MAX8973_CONTROL2, control2);
+        if (ret < 0) {
+                dev_err(max->dev, "register %d write failed, err = %d",
+                                MAX8973_CONTROL2, ret);
+                return ret;
+        }
+
+        /* If external control is enabled then disable EN bit */
+        if (max->enable_external_control) {
+                ret = regmap_update_bits(max->regmap, MAX8973_VOUT,
+                                                MAX8973_VOUT_ENABLE, 0);
+                if (ret < 0)
+                        dev_err(max->dev, "register %d update failed, err = %d",
+                                MAX8973_VOUT, ret);
+        }
+        return ret;
+}
+
+static const struct regmap_config max8973_regmap_config = {
+        .reg_bits               = 8,
+        .val_bits               = 8,
+        .max_register           = MAX8973_CHIPID2,
+        .cache_type             = REGCACHE_RBTREE,
+};
+
+static int __devinit max8973_probe(struct i2c_client *client,
+                                     const struct i2c_device_id *id)
+{
+        struct max8973_regulator_platform_data *pdata;
+        struct regulator_config config = { };
+        struct regulator_dev *rdev;
+        struct max8973_chip *max;
+        int ret;
+
+        pdata = client->dev.platform_data;
+        if (!pdata) {
+                dev_err(&client->dev, "No Platform data");
+                return -EIO;
+        }
+
+        max = devm_kzalloc(&client->dev, sizeof(*max), GFP_KERNEL);
+        if (!max) {
+                dev_err(&client->dev, "Memory allocation for max failed\n");
+                return -ENOMEM;
+        }
+
+        max->regmap = devm_regmap_init_i2c(client, &max8973_regmap_config);
+        if (IS_ERR(max->regmap)) {
+                ret = PTR_ERR(max->regmap);
+                dev_err(&client->dev, "regmap init failed, err %d\n", ret);
+                return ret;
+        }
+
+        i2c_set_clientdata(client, max);
+        max->dev = &client->dev;
+        max->desc.name = id->name;
+        max->desc.id = 0;
+        max->desc.ops = &max8973_dcdc_ops;
+        max->desc.type = REGULATOR_VOLTAGE;
+        max->desc.owner = THIS_MODULE;
+        max->desc.min_uV = MAX8973_MIN_VOLATGE;
+        max->desc.uV_step = MAX8973_VOLATGE_STEP;
+        max->desc.n_voltages = MAX8973_BUCK_N_VOLTAGE;
+
+        if (pdata->enable_ext_control) {
+                max->desc.enable_reg = MAX8973_VOUT;
+                max->desc.enable_mask = MAX8973_VOUT_ENABLE;
+                max8973_dcdc_ops.enable = regulator_is_enabled_regmap;
+                max8973_dcdc_ops.disable = regulator_disable_regmap;
+                max8973_dcdc_ops.is_enabled = regulator_is_enabled_regmap;
+        }
+
+        max->enable_external_control = pdata->enable_ext_control;
+        max->dvs_gpio = pdata->dvs_gpio;
+        max->curr_gpio_val = pdata->dvs_def_state;
+        max->curr_vout_reg = MAX8973_VOUT + pdata->dvs_def_state;
+        max->lru_index[0] = max->curr_vout_reg;
+        max->valid_dvs_gpio = false;
+
+        if (gpio_is_valid(max->dvs_gpio)) {
+                int gpio_flags;
+                int i;
+
+                gpio_flags = (pdata->dvs_def_state) ?
+                                GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW;
+                ret = devm_gpio_request_one(&client->dev, max->dvs_gpio,
+                                gpio_flags, "max8973-dvs");
+                if (ret) {
+                        dev_err(&client->dev,
+                                "gpio_request for gpio %d failed, err = %d\n",
+                                max->dvs_gpio, ret);
+                        return ret;
+                }
+                max->valid_dvs_gpio = true;
+
+                /*
+                 * Initialize the lru index with vout_reg id
+                 * The index 0 will be most recently used and
+                 * set with the max->curr_vout_reg */
+                for (i = 0; i < MAX8973_MAX_VOUT_REG; ++i)
+                        max->lru_index[i] = i;
+                max->lru_index[0] = max->curr_vout_reg;
+                max->lru_index[max->curr_vout_reg] = 0;
+        }
+
+        ret = max8973_init_dcdc(max, pdata);
+        if (ret < 0) {
+                dev_err(max->dev, "Max8973 Init failed, err = %d\n", ret);
+                return ret;
+        }
+
+        config.dev = &client->dev;
+        config.init_data = pdata->reg_init_data;
+        config.driver_data = max;
+        config.of_node = client->dev.of_node;
+        config.regmap = max->regmap;
+
+        /* Register the regulators */
+        rdev = regulator_register(&max->desc, &config);
+        if (IS_ERR(rdev)) {
+                ret = PTR_ERR(rdev);
+                dev_err(max->dev, "regulator register failed, err %d\n", ret);
+                return ret;
+        }
+
+        max->rdev = rdev;
+        return 0;
+}
+
+static int __devexit max8973_remove(struct i2c_client *client)
+{
+        struct max8973_chip *max = i2c_get_clientdata(client);
+
+        regulator_unregister(max->rdev);
+        return 0;
+}
+
+static const struct i2c_device_id max8973_id[] = {
+        {.name = "max8973",},
+        {},
+};
+
+MODULE_DEVICE_TABLE(i2c, max8973_id);
+
+static struct i2c_driver max8973_i2c_driver = {
+        .driver = {
+                .name = "max8973",
+                .owner = THIS_MODULE,
+        },
+        .probe = max8973_probe,
+        .remove = __devexit_p(max8973_remove),
+        .id_table = max8973_id,
+};
+
+static int __init max8973_init(void)
+{
+        return i2c_add_driver(&max8973_i2c_driver);
+}
+subsys_initcall(max8973_init);
+
+static void __exit max8973_cleanup(void)
+{
+        i2c_del_driver(&max8973_i2c_driver);
+}
+module_exit(max8973_cleanup);
+
+MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
+MODULE_DESCRIPTION("MAX8973 voltage regulator driver");
+MODULE_LICENSE("GPL v2");