1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Analog Devices AD5272 digital potentiometer driver
4  * Copyright (C) 2018 Phil Reid <preid@electromag.com.au>
5  *
6  * Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/AD5272_5274.pdf
7  *
8  * DEVID	#Wipers	#Positions	Resistor Opts (kOhm)	i2c address
9  * ad5272	1	1024		20, 50, 100		01011xx
10  * ad5274	1	256		20, 100			01011xx
11  */
12 
13 #include <linux/delay.h>
14 #include <linux/gpio/consumer.h>
15 #include <linux/i2c.h>
16 #include <linux/iio/iio.h>
17 #include <linux/module.h>
18 
19 #define  AD5272_RDAC_WR  1
20 #define  AD5272_RDAC_RD  2
21 #define  AD5272_RESET    4
22 #define  AD5272_CTL      7
23 
24 #define  AD5272_RDAC_WR_EN  BIT(1)
25 
26 struct ad5272_cfg {
27 	int max_pos;
28 	int kohms;
29 	int shift;
30 };
31 
32 enum ad5272_type {
33 	AD5272_020,
34 	AD5272_050,
35 	AD5272_100,
36 	AD5274_020,
37 	AD5274_100,
38 };
39 
40 static const struct ad5272_cfg ad5272_cfg[] = {
41 	[AD5272_020] = { .max_pos = 1024, .kohms = 20 },
42 	[AD5272_050] = { .max_pos = 1024, .kohms = 50 },
43 	[AD5272_100] = { .max_pos = 1024, .kohms = 100 },
44 	[AD5274_020] = { .max_pos = 256,  .kohms = 20,  .shift = 2 },
45 	[AD5274_100] = { .max_pos = 256,  .kohms = 100, .shift = 2 },
46 };
47 
48 struct ad5272_data {
49 	struct i2c_client       *client;
50 	struct mutex            lock;
51 	const struct ad5272_cfg *cfg;
52 	u8                      buf[2] ____cacheline_aligned;
53 };
54 
55 static const struct iio_chan_spec ad5272_channel = {
56 	.type = IIO_RESISTANCE,
57 	.output = 1,
58 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
59 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
60 };
61 
62 static int ad5272_write(struct ad5272_data *data, int reg, int val)
63 {
64 	int ret;
65 
66 	data->buf[0] = (reg << 2) | ((val >> 8) & 0x3);
67 	data->buf[1] = (u8)val;
68 
69 	mutex_lock(&data->lock);
70 	ret = i2c_master_send(data->client, data->buf, sizeof(data->buf));
71 	mutex_unlock(&data->lock);
72 	return ret < 0 ? ret : 0;
73 }
74 
75 static int ad5272_read(struct ad5272_data *data, int reg, int *val)
76 {
77 	int ret;
78 
79 	data->buf[0] = reg << 2;
80 	data->buf[1] = 0;
81 
82 	mutex_lock(&data->lock);
83 	ret = i2c_master_send(data->client, data->buf, sizeof(data->buf));
84 	if (ret < 0)
85 		goto error;
86 
87 	ret = i2c_master_recv(data->client, data->buf, sizeof(data->buf));
88 	if (ret < 0)
89 		goto error;
90 
91 	*val = ((data->buf[0] & 0x3) << 8) | data->buf[1];
92 	ret = 0;
93 error:
94 	mutex_unlock(&data->lock);
95 	return ret;
96 }
97 
98 static int ad5272_read_raw(struct iio_dev *indio_dev,
99 			   struct iio_chan_spec const *chan,
100 			   int *val, int *val2, long mask)
101 {
102 	struct ad5272_data *data = iio_priv(indio_dev);
103 	int ret;
104 
105 	switch (mask) {
106 	case IIO_CHAN_INFO_RAW: {
107 		ret = ad5272_read(data, AD5272_RDAC_RD, val);
108 		*val = *val >> data->cfg->shift;
109 		return ret ? ret : IIO_VAL_INT;
110 	}
111 	case IIO_CHAN_INFO_SCALE:
112 		*val = 1000 * data->cfg->kohms;
113 		*val2 = data->cfg->max_pos;
114 		return IIO_VAL_FRACTIONAL;
115 	}
116 
117 	return -EINVAL;
118 }
119 
120 static int ad5272_write_raw(struct iio_dev *indio_dev,
121 			    struct iio_chan_spec const *chan,
122 			    int val, int val2, long mask)
123 {
124 	struct ad5272_data *data = iio_priv(indio_dev);
125 
126 	if (mask != IIO_CHAN_INFO_RAW)
127 		return -EINVAL;
128 
129 	if (val >= data->cfg->max_pos || val < 0 || val2)
130 		return -EINVAL;
131 
132 	return ad5272_write(data, AD5272_RDAC_WR, val << data->cfg->shift);
133 }
134 
135 static const struct iio_info ad5272_info = {
136 	.read_raw = ad5272_read_raw,
137 	.write_raw = ad5272_write_raw,
138 };
139 
140 static int ad5272_reset(struct ad5272_data *data)
141 {
142 	struct gpio_desc *reset_gpio;
143 
144 	reset_gpio = devm_gpiod_get_optional(&data->client->dev, "reset",
145 		GPIOD_OUT_LOW);
146 	if (IS_ERR(reset_gpio))
147 		return PTR_ERR(reset_gpio);
148 
149 	if (reset_gpio) {
150 		udelay(1);
151 		gpiod_set_value(reset_gpio, 1);
152 	} else {
153 		ad5272_write(data, AD5272_RESET, 0);
154 	}
155 	usleep_range(1000, 2000);
156 
157 	return 0;
158 }
159 
160 static int ad5272_probe(struct i2c_client *client,
161 			const struct i2c_device_id *id)
162 {
163 	struct device *dev = &client->dev;
164 	struct iio_dev *indio_dev;
165 	struct ad5272_data *data;
166 	int ret;
167 
168 	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
169 	if (!indio_dev)
170 		return -ENOMEM;
171 
172 	i2c_set_clientdata(client, indio_dev);
173 
174 	data = iio_priv(indio_dev);
175 	data->client = client;
176 	mutex_init(&data->lock);
177 	data->cfg = &ad5272_cfg[id->driver_data];
178 
179 	ret = ad5272_reset(data);
180 	if (ret)
181 		return ret;
182 
183 	ret = ad5272_write(data, AD5272_CTL, AD5272_RDAC_WR_EN);
184 	if (ret < 0)
185 		return -ENODEV;
186 
187 	indio_dev->info = &ad5272_info;
188 	indio_dev->channels = &ad5272_channel;
189 	indio_dev->num_channels = 1;
190 	indio_dev->name = client->name;
191 
192 	return devm_iio_device_register(dev, indio_dev);
193 }
194 
195 #if defined(CONFIG_OF)
196 static const struct of_device_id ad5272_dt_ids[] = {
197 	{ .compatible = "adi,ad5272-020", .data = (void *)AD5272_020 },
198 	{ .compatible = "adi,ad5272-050", .data = (void *)AD5272_050 },
199 	{ .compatible = "adi,ad5272-100", .data = (void *)AD5272_100 },
200 	{ .compatible = "adi,ad5274-020", .data = (void *)AD5274_020 },
201 	{ .compatible = "adi,ad5274-100", .data = (void *)AD5274_100 },
202 	{}
203 };
204 MODULE_DEVICE_TABLE(of, ad5272_dt_ids);
205 #endif /* CONFIG_OF */
206 
207 static const struct i2c_device_id ad5272_id[] = {
208 	{ "ad5272-020", AD5272_020 },
209 	{ "ad5272-050", AD5272_050 },
210 	{ "ad5272-100", AD5272_100 },
211 	{ "ad5274-020", AD5274_020 },
212 	{ "ad5274-100", AD5274_100 },
213 	{}
214 };
215 MODULE_DEVICE_TABLE(i2c, ad5272_id);
216 
217 static struct i2c_driver ad5272_driver = {
218 	.driver = {
219 		.name	= "ad5272",
220 		.of_match_table = of_match_ptr(ad5272_dt_ids),
221 	},
222 	.probe		= ad5272_probe,
223 	.id_table	= ad5272_id,
224 };
225 
226 module_i2c_driver(ad5272_driver);
227 
228 MODULE_AUTHOR("Phil Reid <preid@eletromag.com.au>");
229 MODULE_DESCRIPTION("AD5272 digital potentiometer");
230 MODULE_LICENSE("GPL v2");
231