ad5272.c

  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
 27struct ad5272_cfg {
 28	int max_pos;
 29	int kohms;
 30	int shift;
 31};
 32
 33enum ad5272_type {
 34	AD5272_020,
 35	AD5272_050,
 36	AD5272_100,
 37	AD5274_020,
 38	AD5274_100,
 39};
 40
 41static 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
 49struct 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
 56static 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
 63static 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
 76static 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;
 94error:
 95	mutex_unlock(&data->lock);
 96	return ret;
 97}
 98
 99static 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
121static 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
136static const struct iio_info ad5272_info = {
137	.read_raw = ad5272_read_raw,
138	.write_raw = ad5272_write_raw,
139};
140
141static 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
161static 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
196static 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};
204MODULE_DEVICE_TABLE(of, ad5272_dt_ids);
205
206static 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};
214MODULE_DEVICE_TABLE(i2c, ad5272_id);
215
216static 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
225module_i2c_driver(ad5272_driver);
226
227MODULE_AUTHOR("Phil Reid <preid@eletromag.com.au>");
228MODULE_DESCRIPTION("AD5272 digital potentiometer");
229MODULE_LICENSE("GPL v2");