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/module.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/regulator/driver.h>
  26 #include <linux/regulator/fixed.h>
  27 #include <linux/gpio.h>
  28 #include <linux/delay.h>
  29 #include <linux/slab.h>
  30
  31 struct fixed_voltage_data {
  32         struct regulator_desc desc;
  33         struct regulator_dev *dev;
  34         int microvolts;
  35         int gpio;
  36         unsigned startup_delay;
  37         bool enable_high;
  38         bool is_enabled;
  39 };
  40
  41 static int fixed_voltage_is_enabled(struct regulator_dev *dev)
  42 {
  43         struct fixed_voltage_data *data = rdev_get_drvdata(dev);
  44
  45         return data->is_enabled;
  46 }
  47
  48 static int fixed_voltage_enable(struct regulator_dev *dev)
  49 {
  50         struct fixed_voltage_data *data = rdev_get_drvdata(dev);
  51
  52         if (gpio_is_valid(data->gpio)) {
  53                 gpio_set_value_cansleep(data->gpio, data->enable_high);
  54                 data->is_enabled = true;
  55         }
  56
  57         return 0;
  58 }
  59
  60 static int fixed_voltage_disable(struct regulator_dev *dev)
  61 {
  62         struct fixed_voltage_data *data = rdev_get_drvdata(dev);
  63
  64         if (gpio_is_valid(data->gpio)) {
  65                 gpio_set_value_cansleep(data->gpio, !data->enable_high);
  66                 data->is_enabled = false;
  67         }
  68
  69         return 0;
  70 }
  71
  72 static int fixed_voltage_enable_time(struct regulator_dev *dev)
  73 {
  74         struct fixed_voltage_data *data = rdev_get_drvdata(dev);
  75
  76         return data->startup_delay;
  77 }
  78
  79 static int fixed_voltage_get_voltage(struct regulator_dev *dev)
  80 {
  81         struct fixed_voltage_data *data = rdev_get_drvdata(dev);
  82
  83         return data->microvolts;
  84 }
  85
  86 static int fixed_voltage_list_voltage(struct regulator_dev *dev,
  87                                       unsigned selector)
  88 {
  89         struct fixed_voltage_data *data = rdev_get_drvdata(dev);
  90
  91         if (selector != 0)
  92                 return -EINVAL;
  93
  94         return data->microvolts;
  95 }
  96
  97 static struct regulator_ops fixed_voltage_ops = {
  98         .is_enabled = fixed_voltage_is_enabled,
  99         .enable = fixed_voltage_enable,
 100         .disable = fixed_voltage_disable,
 101         .enable_time = fixed_voltage_enable_time,
 102         .get_voltage = fixed_voltage_get_voltage,
 103         .list_voltage = fixed_voltage_list_voltage,
 104 };
 105
 106 static int __devinit reg_fixed_voltage_probe(struct platform_device *pdev)
 107 {
 108         struct fixed_voltage_config *config = pdev->dev.platform_data;
 109         struct fixed_voltage_data *drvdata;
 110         int ret;
 111
 112         drvdata = kzalloc(sizeof(struct fixed_voltage_data), GFP_KERNEL);
 113         if (drvdata == NULL) {
 114                 dev_err(&pdev->dev, "Failed to allocate device data\n");
 115                 ret = -ENOMEM;
 116                 goto err;
 117         }
 118
 119         drvdata->desc.name = kstrdup(config->supply_name, GFP_KERNEL);
 120         if (drvdata->desc.name == NULL) {
 121                 dev_err(&pdev->dev, "Failed to allocate supply name\n");
 122                 ret = -ENOMEM;
 123                 goto err;
 124         }
 125         drvdata->desc.type = REGULATOR_VOLTAGE;
 126         drvdata->desc.owner = THIS_MODULE;
 127         drvdata->desc.ops = &fixed_voltage_ops;
 128         drvdata->desc.n_voltages = 1;
 129
 130         drvdata->microvolts = config->microvolts;
 131         drvdata->gpio = config->gpio;
 132         drvdata->startup_delay = config->startup_delay;
 133
 134         if (gpio_is_valid(config->gpio)) {
 135                 drvdata->enable_high = config->enable_high;
 136
 137                 /* FIXME: Remove below print warning
 138                  *
 139                  * config->gpio must be set to -EINVAL by platform code if
 140                  * GPIO control is not required. However, early adopters
 141                  * not requiring GPIO control may forget to initialize
 142                  * config->gpio to -EINVAL. This will cause GPIO 0 to be used
 143                  * for GPIO control.
 144                  *
 145                  * This warning will be removed once there are a couple of users
 146                  * for this driver.
 147                  */
 148                 if (!config->gpio)
 149                         dev_warn(&pdev->dev,
 150                                 "using GPIO 0 for regulator enable control\n");
 151
 152                 ret = gpio_request(config->gpio, config->supply_name);
 153                 if (ret) {
 154                         dev_err(&pdev->dev,
 155                            "Could not obtain regulator enable GPIO %d: %d\n",
 156                                                         config->gpio, ret);
 157                         goto err_name;
 158                 }
 159
 160                 /* set output direction without changing state
 161                  * to prevent glitch
 162                  */
 163                 drvdata->is_enabled = config->enabled_at_boot;
 164                 ret = drvdata->is_enabled ?
 165                                 config->enable_high : !config->enable_high;
 166
 167                 ret = gpio_direction_output(config->gpio, ret);
 168                 if (ret) {
 169                         dev_err(&pdev->dev,
 170                            "Could not configure regulator enable GPIO %d direction: %d\n",
 171                                                         config->gpio, ret);
 172                         goto err_gpio;
 173                 }
 174
 175         } else {
 176                 /* Regulator without GPIO control is considered
 177                  * always enabled
 178                  */
 179                 drvdata->is_enabled = true;
 180         }
 181
 182         drvdata->dev = regulator_register(&drvdata->desc, &pdev->dev,
 183                                           config->init_data, drvdata);
 184         if (IS_ERR(drvdata->dev)) {
 185                 ret = PTR_ERR(drvdata->dev);
 186                 dev_err(&pdev->dev, "Failed to register regulator: %d\n", ret);
 187                 goto err_gpio;
 188         }
 189
 190         platform_set_drvdata(pdev, drvdata);
 191
 192         dev_dbg(&pdev->dev, "%s supplying %duV\n", drvdata->desc.name,
 193                 drvdata->microvolts);
 194
 195         return 0;
 196
 197 err_gpio:
 198         if (gpio_is_valid(config->gpio))
 199                 gpio_free(config->gpio);
 200 err_name:
 201         kfree(drvdata->desc.name);
 202 err:
 203         kfree(drvdata);
 204         return ret;
 205 }
 206
 207 static int __devexit reg_fixed_voltage_remove(struct platform_device *pdev)
 208 {
 209         struct fixed_voltage_data *drvdata = platform_get_drvdata(pdev);
 210
 211         regulator_unregister(drvdata->dev);
 212         if (gpio_is_valid(drvdata->gpio))
 213                 gpio_free(drvdata->gpio);
 214         kfree(drvdata->desc.name);
 215         kfree(drvdata);
 216
 217         return 0;
 218 }
 219
 220 static struct platform_driver regulator_fixed_voltage_driver = {
 221         .probe          = reg_fixed_voltage_probe,
 222         .remove         = __devexit_p(reg_fixed_voltage_remove),
 223         .driver         = {
 224                 .name           = "reg-fixed-voltage",
 225                 .owner          = THIS_MODULE,
 226         },
 227 };
 228
 229 static int __init regulator_fixed_voltage_init(void)
 230 {
 231         return platform_driver_register(&regulator_fixed_voltage_driver);
 232 }
 233 subsys_initcall(regulator_fixed_voltage_init);
 234
 235 static void __exit regulator_fixed_voltage_exit(void)
 236 {
 237         platform_driver_unregister(&regulator_fixed_voltage_driver);
 238 }
 239 module_exit(regulator_fixed_voltage_exit);
 240
 241 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
 242 MODULE_DESCRIPTION("Fixed voltage regulator");
 243 MODULE_LICENSE("GPL");
 244 MODULE_ALIAS("platform:reg-fixed-voltage");