regulator: fixed: support deferred probe for DT GPIOs
[linux-3.10.git] / 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/slab.h>
29 #include <linux/of.h>
30 #include <linux/of_gpio.h>
31 #include <linux/regulator/of_regulator.h>
32 #include <linux/regulator/machine.h>
33
34 struct fixed_voltage_data {
35         struct regulator_desc desc;
36         struct regulator_dev *dev;
37         int microvolts;
38         int gpio;
39         unsigned startup_delay;
40         bool enable_high;
41         bool is_enabled;
42 };
43
44
45 /**
46  * of_get_fixed_voltage_config - extract fixed_voltage_config structure info
47  * @dev: device requesting for fixed_voltage_config
48  *
49  * Populates fixed_voltage_config structure by extracting data from device
50  * tree node, returns a pointer to the populated structure of NULL if memory
51  * alloc fails.
52  */
53 static struct fixed_voltage_config *
54 of_get_fixed_voltage_config(struct device *dev)
55 {
56         struct fixed_voltage_config *config;
57         struct device_node *np = dev->of_node;
58         const __be32 *delay;
59         struct regulator_init_data *init_data;
60
61         config = devm_kzalloc(dev, sizeof(struct fixed_voltage_config),
62                                                                  GFP_KERNEL);
63         if (!config)
64                 return ERR_PTR(-ENOMEM);
65
66         config->init_data = of_get_regulator_init_data(dev, dev->of_node);
67         if (!config->init_data)
68                 return ERR_PTR(-EINVAL);
69
70         init_data = config->init_data;
71         init_data->constraints.apply_uV = 0;
72
73         config->supply_name = init_data->constraints.name;
74         if (init_data->constraints.min_uV == init_data->constraints.max_uV) {
75                 config->microvolts = init_data->constraints.min_uV;
76         } else {
77                 dev_err(dev,
78                          "Fixed regulator specified with variable voltages\n");
79                 return ERR_PTR(-EINVAL);
80         }
81
82         if (init_data->constraints.boot_on)
83                 config->enabled_at_boot = true;
84
85         config->gpio = of_get_named_gpio(np, "gpio", 0);
86         /*
87          * of_get_named_gpio() currently returns ENODEV rather than
88          * EPROBE_DEFER. This code attempts to be compatible with both
89          * for now; the ENODEV check can be removed once the API is fixed.
90          * of_get_named_gpio() doesn't differentiate between a missing
91          * property (which would be fine here, since the GPIO is optional)
92          * and some other error. Patches have been posted for both issues.
93          * Once they are check in, we should replace this with:
94          * if (config->gpio < 0 && config->gpio != -ENOENT)
95          */
96         if ((config->gpio == -ENODEV) || (config->gpio == -EPROBE_DEFER))
97                 return ERR_PTR(-EPROBE_DEFER);
98
99         delay = of_get_property(np, "startup-delay-us", NULL);
100         if (delay)
101                 config->startup_delay = be32_to_cpu(*delay);
102
103         if (of_find_property(np, "enable-active-high", NULL))
104                 config->enable_high = true;
105
106         if (of_find_property(np, "gpio-open-drain", NULL))
107                 config->gpio_is_open_drain = true;
108
109         return config;
110 }
111
112 static int fixed_voltage_is_enabled(struct regulator_dev *dev)
113 {
114         struct fixed_voltage_data *data = rdev_get_drvdata(dev);
115
116         return data->is_enabled;
117 }
118
119 static int fixed_voltage_enable(struct regulator_dev *dev)
120 {
121         struct fixed_voltage_data *data = rdev_get_drvdata(dev);
122
123         gpio_set_value_cansleep(data->gpio, data->enable_high);
124         data->is_enabled = true;
125
126         return 0;
127 }
128
129 static int fixed_voltage_disable(struct regulator_dev *dev)
130 {
131         struct fixed_voltage_data *data = rdev_get_drvdata(dev);
132
133         gpio_set_value_cansleep(data->gpio, !data->enable_high);
134         data->is_enabled = false;
135
136         return 0;
137 }
138
139 static int fixed_voltage_enable_time(struct regulator_dev *dev)
140 {
141         struct fixed_voltage_data *data = rdev_get_drvdata(dev);
142
143         return data->startup_delay;
144 }
145
146 static int fixed_voltage_get_voltage(struct regulator_dev *dev)
147 {
148         struct fixed_voltage_data *data = rdev_get_drvdata(dev);
149
150         if (data->microvolts)
151                 return data->microvolts;
152         else
153                 return -EINVAL;
154 }
155
156 static int fixed_voltage_list_voltage(struct regulator_dev *dev,
157                                       unsigned selector)
158 {
159         struct fixed_voltage_data *data = rdev_get_drvdata(dev);
160
161         if (selector != 0)
162                 return -EINVAL;
163
164         return data->microvolts;
165 }
166
167 static struct regulator_ops fixed_voltage_gpio_ops = {
168         .is_enabled = fixed_voltage_is_enabled,
169         .enable = fixed_voltage_enable,
170         .disable = fixed_voltage_disable,
171         .enable_time = fixed_voltage_enable_time,
172         .get_voltage = fixed_voltage_get_voltage,
173         .list_voltage = fixed_voltage_list_voltage,
174 };
175
176 static struct regulator_ops fixed_voltage_ops = {
177         .get_voltage = fixed_voltage_get_voltage,
178         .list_voltage = fixed_voltage_list_voltage,
179 };
180
181 static int __devinit reg_fixed_voltage_probe(struct platform_device *pdev)
182 {
183         struct fixed_voltage_config *config;
184         struct fixed_voltage_data *drvdata;
185         struct regulator_config cfg = { };
186         int ret;
187
188         if (pdev->dev.of_node) {
189                 config = of_get_fixed_voltage_config(&pdev->dev);
190                 if (IS_ERR(config))
191                         return PTR_ERR(config);
192         } else {
193                 config = pdev->dev.platform_data;
194         }
195
196         if (!config)
197                 return -ENOMEM;
198
199         drvdata = devm_kzalloc(&pdev->dev, sizeof(struct fixed_voltage_data),
200                                GFP_KERNEL);
201         if (drvdata == NULL) {
202                 dev_err(&pdev->dev, "Failed to allocate device data\n");
203                 ret = -ENOMEM;
204                 goto err;
205         }
206
207         drvdata->desc.name = kstrdup(config->supply_name, GFP_KERNEL);
208         if (drvdata->desc.name == NULL) {
209                 dev_err(&pdev->dev, "Failed to allocate supply name\n");
210                 ret = -ENOMEM;
211                 goto err;
212         }
213         drvdata->desc.type = REGULATOR_VOLTAGE;
214         drvdata->desc.owner = THIS_MODULE;
215
216         if (config->microvolts)
217                 drvdata->desc.n_voltages = 1;
218
219         drvdata->microvolts = config->microvolts;
220         drvdata->gpio = config->gpio;
221         drvdata->startup_delay = config->startup_delay;
222
223         if (gpio_is_valid(config->gpio)) {
224                 int gpio_flag;
225                 drvdata->enable_high = config->enable_high;
226
227                 /* FIXME: Remove below print warning
228                  *
229                  * config->gpio must be set to -EINVAL by platform code if
230                  * GPIO control is not required. However, early adopters
231                  * not requiring GPIO control may forget to initialize
232                  * config->gpio to -EINVAL. This will cause GPIO 0 to be used
233                  * for GPIO control.
234                  *
235                  * This warning will be removed once there are a couple of users
236                  * for this driver.
237                  */
238                 if (!config->gpio)
239                         dev_warn(&pdev->dev,
240                                 "using GPIO 0 for regulator enable control\n");
241
242                 /*
243                  * set output direction without changing state
244                  * to prevent glitch
245                  */
246                 drvdata->is_enabled = config->enabled_at_boot;
247                 ret = drvdata->is_enabled ?
248                                 config->enable_high : !config->enable_high;
249                 gpio_flag = ret ? GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW;
250
251                 if (config->gpio_is_open_drain)
252                         gpio_flag |= GPIOF_OPEN_DRAIN;
253
254                 ret = gpio_request_one(config->gpio, gpio_flag,
255                                                 config->supply_name);
256                 if (ret) {
257                         dev_err(&pdev->dev,
258                            "Could not obtain regulator enable GPIO %d: %d\n",
259                                                         config->gpio, ret);
260                         goto err_name;
261                 }
262
263                 drvdata->desc.ops = &fixed_voltage_gpio_ops;
264
265         } else {
266                 drvdata->desc.ops = &fixed_voltage_ops;
267         }
268
269         cfg.dev = &pdev->dev;
270         cfg.init_data = config->init_data;
271         cfg.driver_data = drvdata;
272         cfg.of_node = pdev->dev.of_node;
273
274         drvdata->dev = regulator_register(&drvdata->desc, &cfg);
275         if (IS_ERR(drvdata->dev)) {
276                 ret = PTR_ERR(drvdata->dev);
277                 dev_err(&pdev->dev, "Failed to register regulator: %d\n", ret);
278                 goto err_gpio;
279         }
280
281         platform_set_drvdata(pdev, drvdata);
282
283         dev_dbg(&pdev->dev, "%s supplying %duV\n", drvdata->desc.name,
284                 drvdata->microvolts);
285
286         return 0;
287
288 err_gpio:
289         if (gpio_is_valid(config->gpio))
290                 gpio_free(config->gpio);
291 err_name:
292         kfree(drvdata->desc.name);
293 err:
294         return ret;
295 }
296
297 static int __devexit reg_fixed_voltage_remove(struct platform_device *pdev)
298 {
299         struct fixed_voltage_data *drvdata = platform_get_drvdata(pdev);
300
301         regulator_unregister(drvdata->dev);
302         if (gpio_is_valid(drvdata->gpio))
303                 gpio_free(drvdata->gpio);
304         kfree(drvdata->desc.name);
305
306         return 0;
307 }
308
309 #if defined(CONFIG_OF)
310 static const struct of_device_id fixed_of_match[] __devinitconst = {
311         { .compatible = "regulator-fixed", },
312         {},
313 };
314 MODULE_DEVICE_TABLE(of, fixed_of_match);
315 #endif
316
317 static struct platform_driver regulator_fixed_voltage_driver = {
318         .probe          = reg_fixed_voltage_probe,
319         .remove         = __devexit_p(reg_fixed_voltage_remove),
320         .driver         = {
321                 .name           = "reg-fixed-voltage",
322                 .owner          = THIS_MODULE,
323                 .of_match_table = of_match_ptr(fixed_of_match),
324         },
325 };
326
327 static int __init regulator_fixed_voltage_init(void)
328 {
329         return platform_driver_register(&regulator_fixed_voltage_driver);
330 }
331 subsys_initcall(regulator_fixed_voltage_init);
332
333 static void __exit regulator_fixed_voltage_exit(void)
334 {
335         platform_driver_unregister(&regulator_fixed_voltage_driver);
336 }
337 module_exit(regulator_fixed_voltage_exit);
338
339 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
340 MODULE_DESCRIPTION("Fixed voltage regulator");
341 MODULE_LICENSE("GPL");
342 MODULE_ALIAS("platform:reg-fixed-voltage");