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 #include <linux/mod_devicetable.h>
19 
20 #define  AD5272_RDAC_WR  1
21 #define  AD5272_RDAC_RD  2
22 #define  AD5272_RESET    4
23 #define  AD5272_CTL      7
24 
25 #define  AD5272_RDAC_WR_EN  BIT(1)
26 
27 struct ad5272_cfg {
28 	int max_pos;
29 	int kohms;
30 	int shift;
31 };
32 
33 enum ad5272_type {
34 	AD5272_020,
35 	AD5272_050,
36 	AD5272_100,
37 	AD5274_020,
38 	AD5274_100,
39 };
40 
41 static const struct ad5272_cfg ad5272_cfg[] = {
42 	[AD5272_020] = { .max_pos = 1024, .kohms = 20 },
43 	[AD5272_050] = { .max_pos = 1024, .kohms = 50 },
44 	[AD5272_100] = { .max_pos = 1024, .kohms = 100 },
45 	[AD5274_020] = { .max_pos = 256,  .kohms = 20,  .shift = 2 },
46 	[AD5274_100] = { .max_pos = 256,  .kohms = 100, .shift = 2 },
47 };
48 
49 struct ad5272_data {
50 	struct i2c_client       *client;
51 	struct mutex            lock;
52 	const struct ad5272_cfg *cfg;
53 	u8                      buf[2] __aligned(IIO_DMA_MINALIGN);
54 };
55 
56 static const struct iio_chan_spec ad5272_channel = {
57 	.type = IIO_RESISTANCE,
58 	.output = 1,
59 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
60 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
61 };
62 
63 static int ad5272_write(struct ad5272_data *data, int reg, int val)
64 {
65 	int ret;
66 
67 	data->buf[0] = (reg << 2) | ((val >> 8) & 0x3);
68 	data->buf[1] = (u8)val;
69 
70 	mutex_lock(&data->lock);
71 	ret = i2c_master_send(data->client, data->buf, sizeof(data->buf));
72 	mutex_unlock(&data->lock);
73 	return ret < 0 ? ret : 0;
74 }
75 
76 static int ad5272_read(struct ad5272_data *data, int reg, int *val)
77 {
78 	int ret;
79 
80 	data->buf[0] = reg << 2;
81 	data->buf[1] = 0;
82 
83 	mutex_lock(&data->lock);
84 	ret = i2c_master_send(data->client, data->buf, sizeof(data->buf));
85 	if (ret < 0)
86 		goto error;
87 
88 	ret = i2c_master_recv(data->client, data->buf, sizeof(data->buf));
89 	if (ret < 0)
90 		goto error;
91 
92 	*val = ((data->buf[0] & 0x3) << 8) | data->buf[1];
93 	ret = 0;
94 error:
95 	mutex_unlock(&data->lock);
96 	return ret;
97 }
98 
99 static int ad5272_read_raw(struct iio_dev *indio_dev,
100 			   struct iio_chan_spec const *chan,
101 			   int *val, int *val2, long mask)
102 {
103 	struct ad5272_data *data = iio_priv(indio_dev);
104 	int ret;
105 
106 	switch (mask) {
107 	case IIO_CHAN_INFO_RAW: {
108 		ret = ad5272_read(data, AD5272_RDAC_RD, val);
109 		*val = *val >> data->cfg->shift;
110 		return ret ? ret : IIO_VAL_INT;
111 	}
112 	case IIO_CHAN_INFO_SCALE:
113 		*val = 1000 * data->cfg->kohms;
114 		*val2 = data->cfg->max_pos;
115 		return IIO_VAL_FRACTIONAL;
116 	}
117 
118 	return -EINVAL;
119 }
120 
121 static int ad5272_write_raw(struct iio_dev *indio_dev,
122 			    struct iio_chan_spec const *chan,
123 			    int val, int val2, long mask)
124 {
125 	struct ad5272_data *data = iio_priv(indio_dev);
126 
127 	if (mask != IIO_CHAN_INFO_RAW)
128 		return -EINVAL;
129 
130 	if (val >= data->cfg->max_pos || val < 0 || val2)
131 		return -EINVAL;
132 
133 	return ad5272_write(data, AD5272_RDAC_WR, val << data->cfg->shift);
134 }
135 
136 static const struct iio_info ad5272_info = {
137 	.read_raw = ad5272_read_raw,
138 	.write_raw = ad5272_write_raw,
139 };
140 
141 static int ad5272_reset(struct ad5272_data *data)
142 {
143 	struct gpio_desc *reset_gpio;
144 
145 	reset_gpio = devm_gpiod_get_optional(&data->client->dev, "reset",
146 		GPIOD_OUT_HIGH);
147 	if (IS_ERR(reset_gpio))
148 		return PTR_ERR(reset_gpio);
149 
150 	if (reset_gpio) {
151 		udelay(1);
152 		gpiod_set_value(reset_gpio, 0);
153 	} else {
154 		ad5272_write(data, AD5272_RESET, 0);
155 	}
156 	usleep_range(1000, 2000);
157 
158 	return 0;
159 }
160 
161 static int ad5272_probe(struct i2c_client *client)
162 {
163 	const struct i2c_device_id *id = i2c_client_get_device_id(client);
164 	struct device *dev = &client->dev;
165 	struct iio_dev *indio_dev;
166 	struct ad5272_data *data;
167 	int ret;
168 
169 	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
170 	if (!indio_dev)
171 		return -ENOMEM;
172 
173 	i2c_set_clientdata(client, indio_dev);
174 
175 	data = iio_priv(indio_dev);
176 	data->client = client;
177 	mutex_init(&data->lock);
178 	data->cfg = &ad5272_cfg[id->driver_data];
179 
180 	ret = ad5272_reset(data);
181 	if (ret)
182 		return ret;
183 
184 	ret = ad5272_write(data, AD5272_CTL, AD5272_RDAC_WR_EN);
185 	if (ret < 0)
186 		return -ENODEV;
187 
188 	indio_dev->info = &ad5272_info;
189 	indio_dev->channels = &ad5272_channel;
190 	indio_dev->num_channels = 1;
191 	indio_dev->name = client->name;
192 
193 	return devm_iio_device_register(dev, indio_dev);
194 }
195 
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 
206 static const struct i2c_device_id ad5272_id[] = {
207 	{ "ad5272-020", AD5272_020 },
208 	{ "ad5272-050", AD5272_050 },
209 	{ "ad5272-100", AD5272_100 },
210 	{ "ad5274-020", AD5274_020 },
211 	{ "ad5274-100", AD5274_100 },
212 	{}
213 };
214 MODULE_DEVICE_TABLE(i2c, ad5272_id);
215 
216 static struct i2c_driver ad5272_driver = {
217 	.driver = {
218 		.name	= "ad5272",
219 		.of_match_table = ad5272_dt_ids,
220 	},
221 	.probe		= ad5272_probe,
222 	.id_table	= ad5272_id,
223 };
224 
225 module_i2c_driver(ad5272_driver);
226 
227 MODULE_AUTHOR("Phil Reid <preid@eletromag.com.au>");
228 MODULE_DESCRIPTION("AD5272 digital potentiometer");
229 MODULE_LICENSE("GPL v2");
230