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>

diff --git a/drivers/regulator/fixed.c b/drivers/regulator/fixed.c
index 9c7f956..f8b2957 100644 (file)
--- 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;
 }
 

diff --git a/include/linux/regulator/fixed.h b/include/linux/regulator/fixed.h
index 91b4da3..e94a4a1 100644 (file)
--- a/include/linux/regulator/fixed.h
+++ b/include/linux/regulator/fixed.h
@@ -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
@@ -16,9 +19,30 @@
 
 struct regulator_init_data;
 
+/**
+ * struct fixed_voltage_config - fixed_voltage_config structure
+ * @supply_name:       Name of the regulator supply
+ * @microvolts:                Output voltage of regulator
+ * @gpio:              GPIO to use for enable control
+ *                     set to -EINVAL if not used
+ * @enable_high:       Polarity of enable GPIO
+ *                     1 = Active high, 0 = Active 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
+ * @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 fixed_voltage_config {
        const char *supply_name;
        int microvolts;
+       int gpio;
+       unsigned enable_high:1;
+       unsigned enabled_at_boot:1;
        struct regulator_init_data *init_data;
 };