regulator: Add new driver for ST's PWM controlled voltage regulators

On some STMicroelectronics hardware reside regulators consisting
partly of a PWM input connected to the feedback loop. As the PWM
duty-cycle is varied the output voltage adapts. This driver
allows us to vary the output voltage by adapting the PWM input
duty-cycle.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>

3 files changed, 200 insertions, 0 deletions

diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 6a7932822e37..a6b29cbe8e2b 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -432,6 +432,12 @@ config REGULATOR_S5M8767
          via I2C bus. S5M8767A have 9 Bucks and 28 LDOs output and
          supports DVS mode with 8bits of output voltage control.
 
+config REGULATOR_ST_PWM
+        tristate "STMicroelectronics PWM voltage regulator"
+        depends on ARCH_STI
+        help
+         This driver supports ST's PWM controlled voltage regulators.
+
 config REGULATOR_TI_ABB
         tristate "TI Adaptive Body Bias on-chip LDO"
         depends on ARCH_OMAP
diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
index 979f9ddcf259..d0c2bb85b8cb 100644
--- a/drivers/regulator/Makefile
+++ b/drivers/regulator/Makefile
@@ -59,6 +59,7 @@ obj-$(CONFIG_REGULATOR_PCF50633) += pcf50633-regulator.o
 obj-$(CONFIG_REGULATOR_RC5T583)  += rc5t583-regulator.o
 obj-$(CONFIG_REGULATOR_S2MPS11) += s2mps11.o
 obj-$(CONFIG_REGULATOR_S5M8767) += s5m8767.o
+obj-$(CONFIG_REGULATOR_ST_PWM) += st-pwm.o
 obj-$(CONFIG_REGULATOR_STW481X_VMMC) += stw481x-vmmc.o
 obj-$(CONFIG_REGULATOR_TI_ABB) += ti-abb-regulator.o
 obj-$(CONFIG_REGULATOR_TPS6105X) += tps6105x-regulator.o
diff --git a/drivers/regulator/st-pwm.c b/drivers/regulator/st-pwm.c
new file mode 100644
index 000000000000..6ef569ffd971
--- /dev/null
+++ b/drivers/regulator/st-pwm.c
@@ -0,0 +1,193 @@
+/*
+ * Regulator driver for ST's PWM Regulators
+ *
+ * Copyright (C) 2014 - STMicroelectronics Inc.
+ *
+ * Author: Lee Jones <lee.jones@linaro.org>
+ *
+ * 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/module.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+#include <linux/regulator/of_regulator.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/pwm.h>
+
+#define ST_PWM_REG_PERIOD 8448
+
+struct st_pwm_regulator_pdata {
+        const struct regulator_desc *desc;
+        struct st_pwm_voltages *duty_cycle_table;
+};
+
+struct st_pwm_regulator_data {
+        const struct st_pwm_regulator_pdata *pdata;
+        struct pwm_device *pwm;
+        bool enabled;
+        int state;
+};
+
+struct st_pwm_voltages {
+        unsigned int uV;
+        unsigned int dutycycle;
+};
+
+static int st_pwm_regulator_get_voltage(struct regulator_dev *dev)
+{
+        struct st_pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
+
+        return drvdata->pdata->duty_cycle_table[drvdata->state].uV;
+}
+
+static int st_pwm_regulator_set_voltage_sel(struct regulator_dev *dev,
+                                            unsigned selector)
+{
+        struct st_pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
+        int dutycycle;
+        int ret;
+
+        if (selector >= dev->desc->n_voltages)
+                return -EINVAL;
+
+        dutycycle = (ST_PWM_REG_PERIOD / 100) *
+                drvdata->pdata->duty_cycle_table[selector].dutycycle;
+
+        ret = pwm_config(drvdata->pwm, dutycycle, ST_PWM_REG_PERIOD);
+        if (ret) {
+                dev_err(&dev->dev, "Failed to configure PWM\n");
+                return ret;
+        }
+
+        drvdata->state = selector;
+
+        if (!drvdata->enabled) {
+                ret = pwm_enable(drvdata->pwm);
+                if (ret) {
+                        dev_err(&dev->dev, "Failed to enable PWM\n");
+                        return ret;
+                }
+                drvdata->enabled = true;
+        }
+
+        return 0;
+}
+
+static int st_pwm_regulator_list_voltage(struct regulator_dev *dev,
+                                         unsigned selector)
+{
+        struct st_pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
+
+        if (selector >= dev->desc->n_voltages)
+                return -EINVAL;
+
+        return drvdata->pdata->duty_cycle_table[selector].uV;
+}
+
+static struct regulator_ops st_pwm_regulator_voltage_ops = {
+        .set_voltage_sel = st_pwm_regulator_set_voltage_sel,
+        .get_voltage     = st_pwm_regulator_get_voltage,
+        .list_voltage    = st_pwm_regulator_list_voltage,
+        .map_voltage     = regulator_map_voltage_iterate,
+};
+
+static struct st_pwm_voltages b2105_duty_cycle_table[] = {
+        { .uV = 1114000, .dutycycle = 0,  },
+        { .uV = 1095000, .dutycycle = 10, },
+        { .uV = 1076000, .dutycycle = 20, },
+        { .uV = 1056000, .dutycycle = 30, },
+        { .uV = 1036000, .dutycycle = 40, },
+        { .uV = 1016000, .dutycycle = 50, },
+        /* WARNING: Values above 50% duty-cycle cause boot failures. */
+};
+
+static const struct regulator_desc b2105_desc = {
+        .name           = "b2105-pwm-regulator",
+        .ops            = &st_pwm_regulator_voltage_ops,
+        .type           = REGULATOR_VOLTAGE,
+        .owner          = THIS_MODULE,
+        .n_voltages     = ARRAY_SIZE(b2105_duty_cycle_table),
+        .supply_name    = "pwm",
+};
+
+static const struct st_pwm_regulator_pdata b2105_info = {
+        .desc             = &b2105_desc,
+        .duty_cycle_table = b2105_duty_cycle_table,
+};
+
+static struct of_device_id st_pwm_of_match[] = {
+        { .compatible = "st,b2105-pwm-regulator", .data = &b2105_info, },
+        { },
+};
+MODULE_DEVICE_TABLE(of, st_pwm_of_match);
+
+static int st_pwm_regulator_probe(struct platform_device *pdev)
+{
+        struct st_pwm_regulator_data *drvdata;
+        struct regulator_dev *regulator;
+        struct regulator_config config = { };
+        struct device_node *np = pdev->dev.of_node;
+        const struct of_device_id *of_match;
+
+        if (!np) {
+                dev_err(&pdev->dev, "Device Tree node missing\n");
+                return -EINVAL;
+        }
+
+        drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
+        if (!drvdata)
+                return -ENOMEM;
+
+        of_match = of_match_device(st_pwm_of_match, &pdev->dev);
+        if (!of_match) {
+                dev_err(&pdev->dev, "failed to match of device\n");
+                return -ENODEV;
+        }
+        drvdata->pdata = of_match->data;
+
+        config.init_data = of_get_regulator_init_data(&pdev->dev, np);
+        if (!config.init_data)
+                return -ENOMEM;
+
+        config.of_node = np;
+        config.dev = &pdev->dev;
+        config.driver_data = drvdata;
+
+        drvdata->pwm = devm_pwm_get(&pdev->dev, NULL);
+        if (IS_ERR(drvdata->pwm)) {
+                dev_err(&pdev->dev, "Failed to get PWM\n");
+                return PTR_ERR(drvdata->pwm);
+        }
+
+        regulator = devm_regulator_register(&pdev->dev,
+                                            drvdata->pdata->desc, &config);
+        if (IS_ERR(regulator)) {
+                dev_err(&pdev->dev, "Failed to register regulator %s\n",
+                        drvdata->pdata->desc->name);
+                return PTR_ERR(regulator);
+        }
+
+        return 0;
+}
+
+static struct platform_driver st_pwm_regulator_driver = {
+        .driver = {
+                .name           = "st-pwm-regulator",
+                .owner          = THIS_MODULE,
+                .of_match_table = of_match_ptr(st_pwm_of_match),
+        },
+        .probe = st_pwm_regulator_probe,
+};
+
+module_platform_driver(st_pwm_regulator_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Lee Jones <lee.jones@linaro.org>");
+MODULE_DESCRIPTION("ST PWM Regulator Driver");
+MODULE_ALIAS("platform:st_pwm-regulator");