1/*
2 * Voltage and current regulation for AD5398 and AD5821
3 *
4 * Copyright 2010 Analog Devices Inc.
5 *
6 * Enter bugs at http://blackfin.uclinux.org/
7 *
8 * Licensed under the GPL-2 or later.
9 */
10
11#include <linux/module.h>
12#include <linux/err.h>
13#include <linux/i2c.h>
14#include <linux/slab.h>
15#include <linux/platform_device.h>
16#include <linux/regulator/driver.h>
17#include <linux/regulator/machine.h>
18
19#define AD5398_CURRENT_EN_MASK	0x8000
20
21struct ad5398_chip_info {
22	struct i2c_client *client;
23	int min_uA;
24	int max_uA;
25	unsigned int current_level;
26	unsigned int current_mask;
27	unsigned int current_offset;
28	struct regulator_dev *rdev;
29};
30
31static int ad5398_calc_current(struct ad5398_chip_info *chip,
32	unsigned selector)
33{
34	unsigned range_uA = chip->max_uA - chip->min_uA;
35
36	return chip->min_uA + (selector * range_uA / chip->current_level);
37}
38
39static int ad5398_read_reg(struct i2c_client *client, unsigned short *data)
40{
41	unsigned short val;
42	int ret;
43
44	ret = i2c_master_recv(client, (char *)&val, 2);
45	if (ret < 0) {
46		dev_err(&client->dev, "I2C read error\n");
47		return ret;
48	}
49	*data = be16_to_cpu(val);
50
51	return ret;
52}
53
54static int ad5398_write_reg(struct i2c_client *client, const unsigned short data)
55{
56	unsigned short val;
57	int ret;
58
59	val = cpu_to_be16(data);
60	ret = i2c_master_send(client, (char *)&val, 2);
61	if (ret < 0)
62		dev_err(&client->dev, "I2C write error\n");
63
64	return ret;
65}
66
67static int ad5398_get_current_limit(struct regulator_dev *rdev)
68{
69	struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
70	struct i2c_client *client = chip->client;
71	unsigned short data;
72	int ret;
73
74	ret = ad5398_read_reg(client, &data);
75	if (ret < 0)
76		return ret;
77
78	ret = (data & chip->current_mask) >> chip->current_offset;
79
80	return ad5398_calc_current(chip, ret);
81}
82
83static int ad5398_set_current_limit(struct regulator_dev *rdev, int min_uA, int max_uA)
84{
85	struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
86	struct i2c_client *client = chip->client;
87	unsigned range_uA = chip->max_uA - chip->min_uA;
88	unsigned selector;
89	unsigned short data;
90	int ret;
91
92	if (min_uA < chip->min_uA)
93		min_uA = chip->min_uA;
94	if (max_uA > chip->max_uA)
95		max_uA = chip->max_uA;
96
97	if (min_uA > chip->max_uA || max_uA < chip->min_uA)
98		return -EINVAL;
99
100	selector = DIV_ROUND_UP((min_uA - chip->min_uA) * chip->current_level,
101				range_uA);
102	if (ad5398_calc_current(chip, selector) > max_uA)
103		return -EINVAL;
104
105	dev_dbg(&client->dev, "changing current %duA\n",
106		ad5398_calc_current(chip, selector));
107
108	/* read chip enable bit */
109	ret = ad5398_read_reg(client, &data);
110	if (ret < 0)
111		return ret;
112
113	/* prepare register data */
114	selector = (selector << chip->current_offset) & chip->current_mask;
115	data = (unsigned short)selector | (data & AD5398_CURRENT_EN_MASK);
116
117	/* write the new current value back as well as enable bit */
118	ret = ad5398_write_reg(client, data);
119
120	return ret;
121}
122
123static int ad5398_is_enabled(struct regulator_dev *rdev)
124{
125	struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
126	struct i2c_client *client = chip->client;
127	unsigned short data;
128	int ret;
129
130	ret = ad5398_read_reg(client, &data);
131	if (ret < 0)
132		return ret;
133
134	if (data & AD5398_CURRENT_EN_MASK)
135		return 1;
136	else
137		return 0;
138}
139
140static int ad5398_enable(struct regulator_dev *rdev)
141{
142	struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
143	struct i2c_client *client = chip->client;
144	unsigned short data;
145	int ret;
146
147	ret = ad5398_read_reg(client, &data);
148	if (ret < 0)
149		return ret;
150
151	if (data & AD5398_CURRENT_EN_MASK)
152		return 0;
153
154	data |= AD5398_CURRENT_EN_MASK;
155
156	ret = ad5398_write_reg(client, data);
157
158	return ret;
159}
160
161static int ad5398_disable(struct regulator_dev *rdev)
162{
163	struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
164	struct i2c_client *client = chip->client;
165	unsigned short data;
166	int ret;
167
168	ret = ad5398_read_reg(client, &data);
169	if (ret < 0)
170		return ret;
171
172	if (!(data & AD5398_CURRENT_EN_MASK))
173		return 0;
174
175	data &= ~AD5398_CURRENT_EN_MASK;
176
177	ret = ad5398_write_reg(client, data);
178
179	return ret;
180}
181
182static struct regulator_ops ad5398_ops = {
183	.get_current_limit = ad5398_get_current_limit,
184	.set_current_limit = ad5398_set_current_limit,
185	.enable = ad5398_enable,
186	.disable = ad5398_disable,
187	.is_enabled = ad5398_is_enabled,
188};
189
190static const struct regulator_desc ad5398_reg = {
191	.name = "isink",
192	.id = 0,
193	.ops = &ad5398_ops,
194	.type = REGULATOR_CURRENT,
195	.owner = THIS_MODULE,
196};
197
198struct ad5398_current_data_format {
199	int current_bits;
200	int current_offset;
201	int min_uA;
202	int max_uA;
203};
204
205static const struct ad5398_current_data_format df_10_4_120 = {10, 4, 0, 120000};
206
207static const struct i2c_device_id ad5398_id[] = {
208	{ "ad5398", (kernel_ulong_t)&df_10_4_120 },
209	{ "ad5821", (kernel_ulong_t)&df_10_4_120 },
210	{ }
211};
212MODULE_DEVICE_TABLE(i2c, ad5398_id);
213
214static int ad5398_probe(struct i2c_client *client,
215				const struct i2c_device_id *id)
216{
217	struct regulator_init_data *init_data = dev_get_platdata(&client->dev);
218	struct regulator_config config = { };
219	struct ad5398_chip_info *chip;
220	const struct ad5398_current_data_format *df =
221			(struct ad5398_current_data_format *)id->driver_data;
222
223	if (!init_data)
224		return -EINVAL;
225
226	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
227	if (!chip)
228		return -ENOMEM;
229
230	config.dev = &client->dev;
231	config.init_data = init_data;
232	config.driver_data = chip;
233
234	chip->client = client;
235
236	chip->min_uA = df->min_uA;
237	chip->max_uA = df->max_uA;
238	chip->current_level = 1 << df->current_bits;
239	chip->current_offset = df->current_offset;
240	chip->current_mask = (chip->current_level - 1) << chip->current_offset;
241
242	chip->rdev = devm_regulator_register(&client->dev, &ad5398_reg,
243					     &config);
244	if (IS_ERR(chip->rdev)) {
245		dev_err(&client->dev, "failed to register %s %s\n",
246			id->name, ad5398_reg.name);
247		return PTR_ERR(chip->rdev);
248	}
249
250	i2c_set_clientdata(client, chip);
251	dev_dbg(&client->dev, "%s regulator driver is registered.\n", id->name);
252	return 0;
253}
254
255static struct i2c_driver ad5398_driver = {
256	.probe = ad5398_probe,
257	.driver		= {
258		.name	= "ad5398",
259	},
260	.id_table	= ad5398_id,
261};
262
263static int __init ad5398_init(void)
264{
265	return i2c_add_driver(&ad5398_driver);
266}
267subsys_initcall(ad5398_init);
268
269static void __exit ad5398_exit(void)
270{
271	i2c_del_driver(&ad5398_driver);
272}
273module_exit(ad5398_exit);
274
275MODULE_DESCRIPTION("AD5398 and AD5821 current regulator driver");
276MODULE_AUTHOR("Sonic Zhang");
277MODULE_LICENSE("GPL");
278MODULE_ALIAS("i2c:ad5398-regulator");
279