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