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Subject[RFC] Add gpio based voltage switching regulator
Date
This patch adds support for regulators that can switch between
two voltage levels by setting a gpio.

An example such a regulator is the TI-tps65024x regulator family.
They contain 4 fixed and 1 runtime-switchable voltage regulators.
The switch can be used by a cpufreq driver to set the core
voltage on some SoCs, for example the S3C2416/2450.

Handling of set_voltage calls with a range that fits neither the
low nor the high voltage is determined by the inbetween_high
option. When set to 1 the high voltage is used, on 0 the low
voltage is used and on -EINVAL an error is returned, disallowing
the usage of the voltage range.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>

---
I'm not hung up on the "inbetween handling", in fact at the moment it
seems to not belong there. But I'm not sure on how to handle
frequency tables like
[0] = { 1000000, 1150000 },
[1] = { 1150000, 1250000 },
[2] = { 1250000, 1350000 },
I.e. the middle value should use the voltage in 2 for switch regulators,
but the defined value for more intelligent ones.

drivers/regulator/Kconfig | 8 +
drivers/regulator/Makefile | 1 +
drivers/regulator/switch.c | 320 ++++++++++++++++++++++++++++++++++++++
include/linux/regulator/switch.h | 65 ++++++++
4 files changed, 394 insertions(+), 0 deletions(-)

diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index c7fd2c0..8510d8c 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -45,6 +45,14 @@ config REGULATOR_FIXED_VOLTAGE
useful for systems which use a combination of software
managed regulators and simple non-configurable regulators.

+config REGULATOR_SWITCHED_VOLTAGE
+ tristate "Switched voltage regulator support"
+ help
+ This driver provides support for regulators that can switch
+ between two voltages by setting a gpio,
+ useful for systems which use a combination of software
+ managed regulators and simple non-configurable regulators.
+
config REGULATOR_VIRTUAL_CONSUMER
tristate "Virtual regulator consumer support"
help
diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
index 040d5aa..5a8f4ee 100644
--- a/drivers/regulator/Makefile
+++ b/drivers/regulator/Makefile
@@ -5,6 +5,7 @@

obj-$(CONFIG_REGULATOR) += core.o dummy.o
obj-$(CONFIG_REGULATOR_FIXED_VOLTAGE) += fixed.o
+obj-$(CONFIG_REGULATOR_SWITCHED_VOLTAGE) += switch.o
obj-$(CONFIG_REGULATOR_VIRTUAL_CONSUMER) += virtual.o
obj-$(CONFIG_REGULATOR_USERSPACE_CONSUMER) += userspace-consumer.o

diff --git a/drivers/regulator/switch.c b/drivers/regulator/switch.c
new file mode 100644
index 0000000..012e3e9
--- /dev/null
+++ b/drivers/regulator/switch.c
@@ -0,0 +1,320 @@
+/*
+ * switched.c
+ *
+ * Copyright 2011 Heiko Stuebner <heiko@sntech.de>
+ *
+ * based on fixed.c
+ *
+ * Copyright 2008 Wolfson Microelectronics PLC.
+ *
+ * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
+ *
+ * Copyright (c) 2009 Nokia Corporation
+ * Roger Quadros <ext-roger.quadros@nokia.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; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This is useful for systems with mixed controllable and
+ * non-controllable regulators, as well as for allowing testing on
+ * systems with no controllable regulators.
+ */
+
+#include <linux/err.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+#include <linux/regulator/switch.h>
+#include <linux/gpio.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+
+struct switched_voltage_data {
+ struct regulator_desc desc;
+ struct regulator_dev *dev;
+
+ int microvolts_high;
+ int microvolts_low;
+
+ unsigned startup_delay;
+ int inbetween_high;
+
+ int gpio_enable;
+ int gpio_switch;
+
+ bool switch_high;
+ bool enable_high;
+
+ bool is_switched;
+ bool is_enabled;
+};
+
+static int switched_voltage_is_enabled(struct regulator_dev *dev)
+{
+ struct switched_voltage_data *data = rdev_get_drvdata(dev);
+
+ return data->is_enabled;
+}
+
+static int switched_voltage_enable(struct regulator_dev *dev)
+{
+ struct switched_voltage_data *data = rdev_get_drvdata(dev);
+
+ if (gpio_is_valid(data->gpio_enable)) {
+ gpio_set_value_cansleep(data->gpio_enable, data->enable_high);
+ data->is_enabled = true;
+ }
+
+ return 0;
+}
+
+static int switched_voltage_disable(struct regulator_dev *dev)
+{
+ struct switched_voltage_data *data = rdev_get_drvdata(dev);
+
+ if (gpio_is_valid(data->gpio_enable)) {
+ gpio_set_value_cansleep(data->gpio_enable, !data->enable_high);
+ data->is_enabled = false;
+ }
+
+ return 0;
+}
+
+static int switched_voltage_enable_time(struct regulator_dev *dev)
+{
+ struct switched_voltage_data *data = rdev_get_drvdata(dev);
+
+ return data->startup_delay;
+}
+
+static int switched_voltage_get_voltage(struct regulator_dev *dev)
+{
+ struct switched_voltage_data *data = rdev_get_drvdata(dev);
+
+ return data->is_switched ? data->microvolts_high : data->microvolts_low;
+}
+
+static int switched_voltage_set_voltage(struct regulator_dev *dev,
+ int min_uV, int max_uV,
+ unsigned *selector)
+{
+ struct switched_voltage_data *data = rdev_get_drvdata(dev);
+
+ if (max_uV < data->microvolts_low || min_uV > data->microvolts_high)
+ return -EINVAL;
+
+ if (min_uV <= data->microvolts_low && max_uV >= data->microvolts_low) {
+ gpio_set_value_cansleep(data->gpio_switch, !data->switch_high);
+ data->is_switched = false;
+ return 0;
+ }
+
+ if (min_uV <= data->microvolts_high && max_uV >= data->microvolts_high) {
+ gpio_set_value_cansleep(data->gpio_switch, data->switch_high);
+ data->is_switched = true;
+ return 0;
+ }
+
+ /* target range does not match min_uV or max_uV, inbetween handling */
+ if (data->inbetween_high < 0)
+ return -EINVAL;
+
+ gpio_set_value_cansleep(data->gpio_switch,
+ data->inbetween_high ? data->switch_high
+ : !data->switch_high);
+ data->is_switched = data->inbetween_high ? true : false;
+
+ return 0;
+}
+
+static int switched_voltage_list_voltage(struct regulator_dev *dev,
+ unsigned selector)
+{
+ struct switched_voltage_data *data = rdev_get_drvdata(dev);
+
+ switch (selector) {
+ case 0:
+ return data->microvolts_low;
+ break;
+ case 1:
+ return data->microvolts_high;
+ break;
+ default:
+ return -EINVAL;
+ break;
+ }
+}
+
+static struct regulator_ops switched_voltage_ops = {
+ .is_enabled = switched_voltage_is_enabled,
+ .enable = switched_voltage_enable,
+ .disable = switched_voltage_disable,
+ .enable_time = switched_voltage_enable_time,
+ .get_voltage = switched_voltage_get_voltage,
+ .set_voltage = switched_voltage_set_voltage,
+ .list_voltage = switched_voltage_list_voltage,
+};
+
+static int __devinit reg_switched_voltage_probe(struct platform_device *pdev)
+{
+ struct switched_voltage_config *config = pdev->dev.platform_data;
+ struct switched_voltage_data *drvdata;
+ int ret;
+
+ if (!config->init_data) {
+ dev_err(&pdev->dev, "regulator init_data missing\n");
+ return -EINVAL;
+ }
+
+ drvdata = kzalloc(sizeof(struct switched_voltage_data), GFP_KERNEL);
+ if (drvdata == NULL) {
+ dev_err(&pdev->dev, "Failed to allocate device data\n");
+ return -ENOMEM;
+ }
+
+ drvdata->desc.name = kstrdup(config->supply_name, GFP_KERNEL);
+ if (drvdata->desc.name == NULL) {
+ dev_err(&pdev->dev, "Failed to allocate supply name\n");
+ ret = -ENOMEM;
+ goto err;
+ }
+ drvdata->desc.type = REGULATOR_VOLTAGE;
+ drvdata->desc.owner = THIS_MODULE;
+ drvdata->desc.ops = &switched_voltage_ops;
+ drvdata->desc.n_voltages = 2;
+
+ drvdata->gpio_enable = config->gpio_enable;
+ drvdata->startup_delay = config->startup_delay;
+ drvdata->inbetween_high = config->inbetween_high;
+
+ drvdata->microvolts_low = config->init_data->constraints.min_uV;
+ drvdata->microvolts_high = config->init_data->constraints.max_uV;
+
+ if (gpio_is_valid(config->gpio_enable)) {
+ drvdata->enable_high = config->enable_high;
+
+ ret = gpio_request(config->gpio_enable, config->supply_name);
+ if (ret) {
+ dev_err(&pdev->dev,
+ "Could not obtain regulator enable GPIO %d: %d\n",
+ config->gpio_enable, ret);
+ goto err_name;
+ }
+
+ /* set output direction without changing state
+ * to prevent glitch
+ */
+ drvdata->is_enabled = config->enabled_at_boot;
+ ret = drvdata->is_enabled ?
+ config->enable_high : !config->enable_high;
+
+ ret = gpio_direction_output(config->gpio_enable, ret);
+ if (ret) {
+ dev_err(&pdev->dev,
+ "Could not configure regulator enable GPIO %d direction: %d\n",
+ config->gpio_enable, ret);
+ goto err_gpio;
+ }
+
+ } else {
+ /* Regulator without GPIO control is considered
+ * always enabled
+ */
+ drvdata->is_enabled = true;
+ }
+
+ drvdata->switch_high = config->switch_high;
+
+ ret = gpio_request(config->gpio_switch, config->supply_name);
+ if (ret) {
+ dev_err(&pdev->dev,
+ "Could not obtain regulator switch GPIO %d: %d\n",
+ config->gpio_switch, ret);
+ goto err_gpio;
+ }
+
+ /* set output direction without changing state to prevent glitch */
+ drvdata->is_switched = config->switched_at_boot;
+ ret = drvdata->is_switched ?
+ config->switch_high : !config->switch_high;
+
+ ret = gpio_direction_output(config->gpio_switch, ret);
+ if (ret) {
+ dev_err(&pdev->dev,
+ "Could not configure regulator switch GPIO %d direction: %d\n",
+ config->gpio_switch, ret);
+ goto err_switch;
+ }
+
+ drvdata->dev = regulator_register(&drvdata->desc, &pdev->dev,
+ config->init_data, drvdata);
+ if (IS_ERR(drvdata->dev)) {
+ ret = PTR_ERR(drvdata->dev);
+ dev_err(&pdev->dev, "Failed to register regulator: %d\n", ret);
+ goto err_switch;
+ }
+
+ platform_set_drvdata(pdev, drvdata);
+
+ dev_dbg(&pdev->dev, "%s supplying %d-%duV\n", drvdata->desc.name,
+ drvdata->microvolts_low, drvdata->microvolts_high);
+
+ return 0;
+
+err_switch:
+ gpio_free(config->gpio_switch);
+err_gpio:
+ if (gpio_is_valid(config->gpio_enable))
+ gpio_free(config->gpio_enable);
+err_name:
+ kfree(drvdata->desc.name);
+err:
+ kfree(drvdata);
+ return ret;
+}
+
+static int __devexit reg_switched_voltage_remove(struct platform_device *pdev)
+{
+ struct switched_voltage_data *drvdata = platform_get_drvdata(pdev);
+
+ regulator_unregister(drvdata->dev);
+
+ gpio_free(drvdata->gpio_switch);
+
+ if (gpio_is_valid(drvdata->gpio_enable))
+ gpio_free(drvdata->gpio_enable);
+
+ kfree(drvdata->desc.name);
+ kfree(drvdata);
+
+ return 0;
+}
+
+static struct platform_driver regulator_switched_voltage_driver = {
+ .probe = reg_switched_voltage_probe,
+ .remove = __devexit_p(reg_switched_voltage_remove),
+ .driver = {
+ .name = "reg-switched-voltage",
+ .owner = THIS_MODULE,
+ },
+};
+
+static int __init regulator_switched_voltage_init(void)
+{
+ return platform_driver_register(&regulator_switched_voltage_driver);
+}
+subsys_initcall(regulator_switched_voltage_init);
+
+static void __exit regulator_switched_voltage_exit(void)
+{
+ platform_driver_unregister(&regulator_switched_voltage_driver);
+}
+module_exit(regulator_switched_voltage_exit);
+
+MODULE_AUTHOR("Heiko Stuebner <heiko@sntech.de>");
+MODULE_DESCRIPTION("switched voltage regulator");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:reg-switched-voltage");
diff --git a/include/linux/regulator/switch.h b/include/linux/regulator/switch.h
new file mode 100644
index 0000000..cd013e9
--- /dev/null
+++ b/include/linux/regulator/switch.h
@@ -0,0 +1,65 @@
+/*
+ * switch.h
+ *
+ * based on fixed.h
+ *
+ * Copyright 2008 Wolfson Microelectronics PLC.
+ *
+ * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
+ *
+ * Copyright (c) 2009 Nokia Corporation
+ * Roger Quadros <ext-roger.quadros@nokia.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; either version 2 of the
+ * License, or (at your option) any later version.
+ */
+
+#ifndef __REGULATOR_SWITCHED_H
+#define __REGULATOR_SWITCHED_H
+
+struct regulator_init_data;
+
+/**
+ * struct switched_voltage_config - fixed_voltage_config structure
+ * @supply_name: Name of the regulator supply
+ * @gpio_enable: GPIO to use for enable control
+ * set to -EINVAL if not used
+ * @gpio_switch: GPIO to use for switching voltages
+ * @startup_delay: Start-up time in microseconds
+ * @enable_high: Polarity of enable GPIO
+ * 1 = Active high, 0 = Active low
+ * @switch_high: Polarity of witch GPIO
+ * 1 = max_voltage as high, 0 = max_voltage as low
+ * @enabled_at_boot: Whether regulator has been enabled at
+ * boot or not. 1 = Yes, 0 = No
+ * This is used to keep the regulator at
+ * the default state
+ * @switched_at_boot: Whether voltage is high at boot or not.
+ * 1 = Yes, 0 = No
+ * This is used to keep the regulator at
+ * the default state
+ * @inbetween_high: How to handle voltage request that match neither
+ * min_uV nor max_uV. Set to -EINVAL to return error or
+ * 1 = set to max_uV, 0 = set to min_uV
+ * @init_data: regulator_init_data
+ *
+ * This structure contains fixed voltage regulator configuration
+ * information that must be passed by platform code to the fixed
+ * voltage regulator driver.
+ */
+struct switched_voltage_config {
+ const char *supply_name;
+ int gpio_enable;
+ int gpio_switch;
+ unsigned startup_delay;
+ unsigned enable_high:1;
+ unsigned switch_high:1;
+ unsigned enabled_at_boot:1;
+ unsigned switched_at_boot:1;
+ int inbetween_high;
+ struct regulator_init_data *init_data;
+};
+
+#endif
--
tg: (c6a389f..) topic/drivers/reg-switch (depends on: master)

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