drivers/regulator/fixed.c

   1 /*
   2  * fixed.c
   3  *
   4  * Copyright 2008 Wolfson Microelectronics PLC.
   5  *
   6  * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
   7  *
   8  * Copyright (c) 2009 Nokia Corporation
   9  * Roger Quadros <ext-roger.quadros@nokia.com>
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License as
  13  * published by the Free Software Foundation; either version 2 of the
  14  * License, or (at your option) any later version.
  15  *
  16  * This is useful for systems with mixed controllable and
  17  * non-controllable regulators, as well as for allowing testing on
  18  * systems with no controllable regulators.
  19  */
  20
  21 #include <linux/err.h>
  22 #include <linux/mutex.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/regulator/driver.h>
  25 #include <linux/regulator/fixed.h>
  26 #include <linux/gpio.h>
  27
  28 struct fixed_voltage_data {
  29         struct regulator_desc desc;
  30         struct regulator_dev *dev;
  31         int microvolts;
  32         int gpio;
  33         unsigned enable_high:1;
  34         unsigned is_enabled:1;
  35 };
  36
  37 static int fixed_voltage_is_enabled(struct regulator_dev *dev)
  38 {
  39         struct fixed_voltage_data *data = rdev_get_drvdata(dev);
  40
  41         return data->is_enabled;
  42 }
  43
  44 static int fixed_voltage_enable(struct regulator_dev *dev)
  45 {
  46         struct fixed_voltage_data *data = rdev_get_drvdata(dev);
  47
  48         if (gpio_is_valid(data->gpio)) {
  49                 gpio_set_value_cansleep(data->gpio, data->enable_high);
  50                 data->is_enabled = 1;
  51         }
  52
  53         return 0;
  54 }
  55
  56 static int fixed_voltage_disable(struct regulator_dev *dev)
  57 {
  58         struct fixed_voltage_data *data = rdev_get_drvdata(dev);
  59
  60         if (gpio_is_valid(data->gpio)) {
  61                 gpio_set_value_cansleep(data->gpio, !data->enable_high);
  62                 data->is_enabled = 0;
  63         }
  64
  65         return 0;
  66 }
  67
  68 static int fixed_voltage_get_voltage(struct regulator_dev *dev)
  69 {
  70         struct fixed_voltage_data *data = rdev_get_drvdata(dev);
  71
  72         return data->microvolts;
  73 }
  74
  75 static int fixed_voltage_list_voltage(struct regulator_dev *dev,
  76                                       unsigned selector)
  77 {
  78         struct fixed_voltage_data *data = rdev_get_drvdata(dev);
  79
  80         if (selector != 0)
  81                 return -EINVAL;
  82
  83         return data->microvolts;
  84 }
  85
  86 static struct regulator_ops fixed_voltage_ops = {
  87         .is_enabled = fixed_voltage_is_enabled,
  88         .enable = fixed_voltage_enable,
  89         .disable = fixed_voltage_disable,
  90         .get_voltage = fixed_voltage_get_voltage,
  91         .list_voltage = fixed_voltage_list_voltage,
  92 };
  93
  94 static int regulator_fixed_voltage_probe(struct platform_device *pdev)
  95 {
  96         struct fixed_voltage_config *config = pdev->dev.platform_data;
  97         struct fixed_voltage_data *drvdata;
  98         int ret;
  99
 100         drvdata = kzalloc(sizeof(struct fixed_voltage_data), GFP_KERNEL);
 101         if (drvdata == NULL) {
 102                 dev_err(&pdev->dev, "Failed to allocate device data\n");
 103                 ret = -ENOMEM;
 104                 goto err;
 105         }
 106
 107         drvdata->desc.name = kstrdup(config->supply_name, GFP_KERNEL);
 108         if (drvdata->desc.name == NULL) {
 109                 dev_err(&pdev->dev, "Failed to allocate supply name\n");
 110                 ret = -ENOMEM;
 111                 goto err;
 112         }
 113         drvdata->desc.type = REGULATOR_VOLTAGE;
 114         drvdata->desc.owner = THIS_MODULE;
 115         drvdata->desc.ops = &fixed_voltage_ops;
 116         drvdata->desc.n_voltages = 1;
 117
 118         drvdata->microvolts = config->microvolts;
 119         drvdata->gpio = config->gpio;
 120
 121         if (gpio_is_valid(config->gpio)) {
 122                 drvdata->enable_high = config->enable_high;
 123
 124                 /* FIXME: Remove below print warning
 125                  *
 126                  * config->gpio must be set to -EINVAL by platform code if
 127                  * GPIO control is not required. However, early adopters
 128                  * not requiring GPIO control may forget to initialize
 129                  * config->gpio to -EINVAL. This will cause GPIO 0 to be used
 130                  * for GPIO control.
 131                  *
 132                  * This warning will be removed once there are a couple of users
 133                  * for this driver.
 134                  */
 135                 if (!config->gpio)
 136                         dev_warn(&pdev->dev,
 137                                 "using GPIO 0 for regulator enable control\n");
 138
 139                 ret = gpio_request(config->gpio, config->supply_name);
 140                 if (ret) {
 141                         dev_err(&pdev->dev,
 142                            "Could not obtain regulator enable GPIO %d: %d\n",
 143                                                         config->gpio, ret);
 144                         goto err_name;
 145                 }
 146
 147                 /* set output direction without changing state
 148                  * to prevent glitch
 149                  */
 150                 drvdata->is_enabled = config->enabled_at_boot;
 151                 ret = drvdata->is_enabled ?
 152                                 config->enable_high : !config->enable_high;
 153
 154                 ret = gpio_direction_output(config->gpio, ret);
 155                 if (ret) {
 156                         dev_err(&pdev->dev,
 157                            "Could not configure regulator enable GPIO %d direction: %d\n",
 158                                                         config->gpio, ret);
 159                         goto err_gpio;
 160                 }
 161
 162         } else {
 163                 /* Regulator without GPIO control is considered
 164                  * always enabled
 165                  */
 166                 drvdata->is_enabled = 1;
 167         }
 168
 169         drvdata->dev = regulator_register(&drvdata->desc, &pdev->dev,
 170                                           config->init_data, drvdata);
 171         if (IS_ERR(drvdata->dev)) {
 172                 ret = PTR_ERR(drvdata->dev);
 173                 dev_err(&pdev->dev, "Failed to register regulator: %d\n", ret);
 174                 goto err_gpio;
 175         }
 176
 177         platform_set_drvdata(pdev, drvdata);
 178
 179         dev_dbg(&pdev->dev, "%s supplying %duV\n", drvdata->desc.name,
 180                 drvdata->microvolts);
 181
 182         return 0;
 183
 184 err_gpio:
 185         if (gpio_is_valid(config->gpio))
 186                 gpio_free(config->gpio);
 187 err_name:
 188         kfree(drvdata->desc.name);
 189 err:
 190         kfree(drvdata);
 191         return ret;
 192 }
 193
 194 static int regulator_fixed_voltage_remove(struct platform_device *pdev)
 195 {
 196         struct fixed_voltage_data *drvdata = platform_get_drvdata(pdev);
 197
 198         regulator_unregister(drvdata->dev);
 199         kfree(drvdata->desc.name);
 200         kfree(drvdata);
 201
 202         if (gpio_is_valid(drvdata->gpio))
 203                 gpio_free(drvdata->gpio);
 204
 205         return 0;
 206 }
 207
 208 static struct platform_driver regulator_fixed_voltage_driver = {
 209         .probe          = regulator_fixed_voltage_probe,
 210         .remove         = regulator_fixed_voltage_remove,
 211         .driver         = {
 212                 .name           = "reg-fixed-voltage",
 213         },
 214 };
 215
 216 static int __init regulator_fixed_voltage_init(void)
 217 {
 218         return platform_driver_register(&regulator_fixed_voltage_driver);
 219 }
 220 subsys_initcall(regulator_fixed_voltage_init);
 221
 222 static void __exit regulator_fixed_voltage_exit(void)
 223 {
 224         platform_driver_unregister(&regulator_fixed_voltage_driver);
 225 }
 226 module_exit(regulator_fixed_voltage_exit);
 227
 228 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
 229 MODULE_DESCRIPTION("Fixed voltage regulator");
 230 MODULE_LICENSE("GPL");
 231 MODULE_ALIAS("platform:reg-fixed-voltage");