regulator: Add GPIO enable control to fixed voltage regulator driver

Now fixed regulators that have their enable pin connected to a GPIO line
can use the fixed regulator driver for regulator enable/disable control.
The GPIO number and polarity information is passed through platform data.
GPIO enable control is achieved using gpiolib.

Signed-off-by: Roger Quadros <ext-roger.quadros@nokia.com>
Reviewed-by: Philipp Zabel <philipp.zabel@gmail.com>
Reviewed-by: Felipe Balbi <felipe.balbi@nokia.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

1 files changed, 86 insertions, 2 deletions

diff --git a/drivers/regulator/fixed.c b/drivers/regulator/fixed.c
index 9c7f956d57c4..f8b295700d7d 100644
--- a/drivers/regulator/fixed.c
+++ b/drivers/regulator/fixed.c
@@ -5,6 +5,9 @@
  *
  * 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
@@ -20,20 +23,45 @@
 #include <linux/platform_device.h>
 #include <linux/regulator/driver.h>
 #include <linux/regulator/fixed.h>
+#include <linux/gpio.h>
 
 struct fixed_voltage_data {
         struct regulator_desc desc;
         struct regulator_dev *dev;
         int microvolts;
+        int gpio;
+        unsigned enable_high:1;
+        unsigned is_enabled:1;
 };
 
 static int fixed_voltage_is_enabled(struct regulator_dev *dev)
 {
-        return 1;
+        struct fixed_voltage_data *data = rdev_get_drvdata(dev);
+
+        return data->is_enabled;
 }
 
 static int fixed_voltage_enable(struct regulator_dev *dev)
 {
+        struct fixed_voltage_data *data = rdev_get_drvdata(dev);
+
+        if (gpio_is_valid(data->gpio)) {
+                gpio_set_value_cansleep(data->gpio, data->enable_high);
+                data->is_enabled = 1;
+        }
+
+        return 0;
+}
+
+static int fixed_voltage_disable(struct regulator_dev *dev)
+{
+        struct fixed_voltage_data *data = rdev_get_drvdata(dev);
+
+        if (gpio_is_valid(data->gpio)) {
+                gpio_set_value_cansleep(data->gpio, !data->enable_high);
+                data->is_enabled = 0;
+        }
+
         return 0;
 }
 
@@ -58,6 +86,7 @@ static int fixed_voltage_list_voltage(struct regulator_dev *dev,
 static struct regulator_ops fixed_voltage_ops = {
         .is_enabled = fixed_voltage_is_enabled,
         .enable = fixed_voltage_enable,
+        .disable = fixed_voltage_disable,
         .get_voltage = fixed_voltage_get_voltage,
         .list_voltage = fixed_voltage_list_voltage,
 };
@@ -87,13 +116,62 @@ static int regulator_fixed_voltage_probe(struct platform_device *pdev)
         drvdata->desc.n_voltages = 1;
 
         drvdata->microvolts = config->microvolts;
+        drvdata->gpio = config->gpio;
+
+        if (gpio_is_valid(config->gpio)) {
+                drvdata->enable_high = config->enable_high;
+
+                /* FIXME: Remove below print warning
+                 *
+                 * config->gpio must be set to -EINVAL by platform code if
+                 * GPIO control is not required. However, early adopters
+                 * not requiring GPIO control may forget to initialize
+                 * config->gpio to -EINVAL. This will cause GPIO 0 to be used
+                 * for GPIO control.
+                 *
+                 * This warning will be removed once there are a couple of users
+                 * for this driver.
+                 */
+                if (!config->gpio)
+                        dev_warn(&pdev->dev,
+                                "using GPIO 0 for regulator enable control\n");
+
+                ret = gpio_request(config->gpio, config->supply_name);
+                if (ret) {
+                        dev_err(&pdev->dev,
+                           "Could not obtain regulator enable GPIO %d: %d\n",
+                                                        config->gpio, 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, ret);
+                if (ret) {
+                        dev_err(&pdev->dev,
+                           "Could not configure regulator enable GPIO %d direction: %d\n",
+                                                        config->gpio, ret);
+                        goto err_gpio;
+                }
+
+        } else {
+                /* Regulator without GPIO control is considered
+                 * always enabled
+                 */
+                drvdata->is_enabled = 1;
+        }
 
         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_name;
+                goto err_gpio;
         }
 
         platform_set_drvdata(pdev, drvdata);
@@ -103,6 +181,9 @@ static int regulator_fixed_voltage_probe(struct platform_device *pdev)
 
         return 0;
 
+err_gpio:
+        if (gpio_is_valid(config->gpio))
+                gpio_free(config->gpio);
 err_name:
         kfree(drvdata->desc.name);
 err:
@@ -118,6 +199,9 @@ static int regulator_fixed_voltage_remove(struct platform_device *pdev)
         kfree(drvdata->desc.name);
         kfree(drvdata);
 
+        if (gpio_is_valid(drvdata->gpio))
+                gpio_free(drvdata->gpio);
+
         return 0;
 }