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 
21 struct 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 
ad5398_calc_current(struct ad5398_chip_info * chip,unsigned selector)31 static 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 
ad5398_read_reg(struct i2c_client * client,unsigned short * data)39 static 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 
ad5398_write_reg(struct i2c_client * client,const unsigned short data)54 static 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 != 2) {
62 		dev_err(&client->dev, "I2C write error\n");
63 		return ret < 0 ? ret : -EIO;
64 	}
65 
66 	return 0;
67 }
68 
ad5398_get_current_limit(struct regulator_dev * rdev)69 static int ad5398_get_current_limit(struct regulator_dev *rdev)
70 {
71 	struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
72 	struct i2c_client *client = chip->client;
73 	unsigned short data;
74 	int ret;
75 
76 	ret = ad5398_read_reg(client, &data);
77 	if (ret < 0)
78 		return ret;
79 
80 	ret = (data & chip->current_mask) >> chip->current_offset;
81 
82 	return ad5398_calc_current(chip, ret);
83 }
84 
ad5398_set_current_limit(struct regulator_dev * rdev,int min_uA,int max_uA)85 static int ad5398_set_current_limit(struct regulator_dev *rdev, int min_uA, int max_uA)
86 {
87 	struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
88 	struct i2c_client *client = chip->client;
89 	unsigned range_uA = chip->max_uA - chip->min_uA;
90 	unsigned selector;
91 	unsigned short data;
92 	int ret;
93 
94 	if (min_uA < chip->min_uA)
95 		min_uA = chip->min_uA;
96 	if (max_uA > chip->max_uA)
97 		max_uA = chip->max_uA;
98 
99 	if (min_uA > chip->max_uA || max_uA < chip->min_uA)
100 		return -EINVAL;
101 
102 	selector = DIV_ROUND_UP((min_uA - chip->min_uA) * chip->current_level,
103 				range_uA);
104 	if (ad5398_calc_current(chip, selector) > max_uA)
105 		return -EINVAL;
106 
107 	dev_dbg(&client->dev, "changing current %duA\n",
108 		ad5398_calc_current(chip, selector));
109 
110 	/* read chip enable bit */
111 	ret = ad5398_read_reg(client, &data);
112 	if (ret < 0)
113 		return ret;
114 
115 	/* prepare register data */
116 	selector = (selector << chip->current_offset) & chip->current_mask;
117 	data = (unsigned short)selector | (data & AD5398_CURRENT_EN_MASK);
118 
119 	/* write the new current value back as well as enable bit */
120 	ret = ad5398_write_reg(client, data);
121 
122 	return ret;
123 }
124 
ad5398_is_enabled(struct regulator_dev * rdev)125 static int ad5398_is_enabled(struct regulator_dev *rdev)
126 {
127 	struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
128 	struct i2c_client *client = chip->client;
129 	unsigned short data;
130 	int ret;
131 
132 	ret = ad5398_read_reg(client, &data);
133 	if (ret < 0)
134 		return ret;
135 
136 	if (data & AD5398_CURRENT_EN_MASK)
137 		return 1;
138 	else
139 		return 0;
140 }
141 
ad5398_enable(struct regulator_dev * rdev)142 static int ad5398_enable(struct regulator_dev *rdev)
143 {
144 	struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
145 	struct i2c_client *client = chip->client;
146 	unsigned short data;
147 	int ret;
148 
149 	ret = ad5398_read_reg(client, &data);
150 	if (ret < 0)
151 		return ret;
152 
153 	if (data & AD5398_CURRENT_EN_MASK)
154 		return 0;
155 
156 	data |= AD5398_CURRENT_EN_MASK;
157 
158 	ret = ad5398_write_reg(client, data);
159 
160 	return ret;
161 }
162 
ad5398_disable(struct regulator_dev * rdev)163 static int ad5398_disable(struct regulator_dev *rdev)
164 {
165 	struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
166 	struct i2c_client *client = chip->client;
167 	unsigned short data;
168 	int ret;
169 
170 	ret = ad5398_read_reg(client, &data);
171 	if (ret < 0)
172 		return ret;
173 
174 	if (!(data & AD5398_CURRENT_EN_MASK))
175 		return 0;
176 
177 	data &= ~AD5398_CURRENT_EN_MASK;
178 
179 	ret = ad5398_write_reg(client, data);
180 
181 	return ret;
182 }
183 
184 static const struct regulator_ops ad5398_ops = {
185 	.get_current_limit = ad5398_get_current_limit,
186 	.set_current_limit = ad5398_set_current_limit,
187 	.enable = ad5398_enable,
188 	.disable = ad5398_disable,
189 	.is_enabled = ad5398_is_enabled,
190 };
191 
192 static const struct regulator_desc ad5398_reg = {
193 	.name = "isink",
194 	.id = 0,
195 	.ops = &ad5398_ops,
196 	.type = REGULATOR_CURRENT,
197 	.owner = THIS_MODULE,
198 };
199 
200 struct ad5398_current_data_format {
201 	int current_bits;
202 	int current_offset;
203 	int min_uA;
204 	int max_uA;
205 };
206 
207 static const struct ad5398_current_data_format df_10_4_120 = {10, 4, 0, 120000};
208 
209 static const struct i2c_device_id ad5398_id[] = {
210 	{ "ad5398", (kernel_ulong_t)&df_10_4_120 },
211 	{ "ad5821", (kernel_ulong_t)&df_10_4_120 },
212 	{ }
213 };
214 MODULE_DEVICE_TABLE(i2c, ad5398_id);
215 
ad5398_probe(struct i2c_client * client,const struct i2c_device_id * id)216 static int ad5398_probe(struct i2c_client *client,
217 				const struct i2c_device_id *id)
218 {
219 	struct regulator_init_data *init_data = dev_get_platdata(&client->dev);
220 	struct regulator_config config = { };
221 	struct ad5398_chip_info *chip;
222 	const struct ad5398_current_data_format *df =
223 			(struct ad5398_current_data_format *)id->driver_data;
224 
225 	if (!init_data)
226 		return -EINVAL;
227 
228 	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
229 	if (!chip)
230 		return -ENOMEM;
231 
232 	config.dev = &client->dev;
233 	config.init_data = init_data;
234 	config.driver_data = chip;
235 
236 	chip->client = client;
237 
238 	chip->min_uA = df->min_uA;
239 	chip->max_uA = df->max_uA;
240 	chip->current_level = 1 << df->current_bits;
241 	chip->current_offset = df->current_offset;
242 	chip->current_mask = (chip->current_level - 1) << chip->current_offset;
243 
244 	chip->rdev = devm_regulator_register(&client->dev, &ad5398_reg,
245 					     &config);
246 	if (IS_ERR(chip->rdev)) {
247 		dev_err(&client->dev, "failed to register %s %s\n",
248 			id->name, ad5398_reg.name);
249 		return PTR_ERR(chip->rdev);
250 	}
251 
252 	i2c_set_clientdata(client, chip);
253 	dev_dbg(&client->dev, "%s regulator driver is registered.\n", id->name);
254 	return 0;
255 }
256 
257 static struct i2c_driver ad5398_driver = {
258 	.probe = ad5398_probe,
259 	.driver		= {
260 		.name	= "ad5398",
261 	},
262 	.id_table	= ad5398_id,
263 };
264 
ad5398_init(void)265 static int __init ad5398_init(void)
266 {
267 	return i2c_add_driver(&ad5398_driver);
268 }
269 subsys_initcall(ad5398_init);
270 
ad5398_exit(void)271 static void __exit ad5398_exit(void)
272 {
273 	i2c_del_driver(&ad5398_driver);
274 }
275 module_exit(ad5398_exit);
276 
277 MODULE_DESCRIPTION("AD5398 and AD5821 current regulator driver");
278 MODULE_AUTHOR("Sonic Zhang");
279 MODULE_LICENSE("GPL");
280