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