drivers/iio/potentiometer/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
  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");