drivers/iio/dac/mcp4725.c

   1 /*
   2  * mcp4725.c - Support for Microchip MCP4725
   3  *
   4  * Copyright (C) 2012 Peter Meerwald <pmeerw@pmeerw.net>
   5  *
   6  * Based on max517 by Roland Stigge <stigge@antcom.de>
   7  *
   8  * This file is subject to the terms and conditions of version 2 of
   9  * the GNU General Public License.  See the file COPYING in the main
  10  * directory of this archive for more details.
  11  *
  12  * driver for the Microchip I2C 12-bit digital-to-analog converter (DAC)
  13  * (7-bit I2C slave address 0x60, the three LSBs can be configured in
  14  * hardware)
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/i2c.h>
  19 #include <linux/err.h>
  20 #include <linux/delay.h>
  21
  22 #include <linux/iio/iio.h>
  23 #include <linux/iio/sysfs.h>
  24
  25 #include <linux/iio/dac/mcp4725.h>
  26
  27 #define MCP4725_DRV_NAME "mcp4725"
  28
  29 struct mcp4725_data {
  30         struct i2c_client *client;
  31         u16 vref_mv;
  32         u16 dac_value;
  33         bool powerdown;
  34         unsigned powerdown_mode;
  35 };
  36
  37 static int mcp4725_suspend(struct device *dev)
  38 {
  39         struct mcp4725_data *data = iio_priv(i2c_get_clientdata(
  40                 to_i2c_client(dev)));
  41         u8 outbuf[2];
  42
  43         outbuf[0] = (data->powerdown_mode + 1) << 4;
  44         outbuf[1] = 0;
  45         data->powerdown = true;
  46
  47         return i2c_master_send(data->client, outbuf, 2);
  48 }
  49
  50 static int mcp4725_resume(struct device *dev)
  51 {
  52         struct mcp4725_data *data = iio_priv(i2c_get_clientdata(
  53                 to_i2c_client(dev)));
  54         u8 outbuf[2];
  55
  56         /* restore previous DAC value */
  57         outbuf[0] = (data->dac_value >> 8) & 0xf;
  58         outbuf[1] = data->dac_value & 0xff;
  59         data->powerdown = false;
  60
  61         return i2c_master_send(data->client, outbuf, 2);
  62 }
  63
  64 #ifdef CONFIG_PM_SLEEP
  65 static SIMPLE_DEV_PM_OPS(mcp4725_pm_ops, mcp4725_suspend, mcp4725_resume);
  66 #define MCP4725_PM_OPS (&mcp4725_pm_ops)
  67 #else
  68 #define MCP4725_PM_OPS NULL
  69 #endif
  70
  71 static ssize_t mcp4725_store_eeprom(struct device *dev,
  72         struct device_attribute *attr, const char *buf, size_t len)
  73 {
  74         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  75         struct mcp4725_data *data = iio_priv(indio_dev);
  76         int tries = 20;
  77         u8 inoutbuf[3];
  78         bool state;
  79         int ret;
  80
  81         ret = strtobool(buf, &state);
  82         if (ret < 0)
  83                 return ret;
  84
  85         if (!state)
  86                 return 0;
  87
  88         inoutbuf[0] = 0x60; /* write EEPROM */
  89         inoutbuf[1] = data->dac_value >> 4;
  90         inoutbuf[2] = (data->dac_value & 0xf) << 4;
  91
  92         ret = i2c_master_send(data->client, inoutbuf, 3);
  93         if (ret < 0)
  94                 return ret;
  95         else if (ret != 3)
  96                 return -EIO;
  97
  98         /* wait for write complete, takes up to 50ms */
  99         while (tries--) {
 100                 msleep(20);
 101                 ret = i2c_master_recv(data->client, inoutbuf, 3);
 102                 if (ret < 0)
 103                         return ret;
 104                 else if (ret != 3)
 105                         return -EIO;
 106
 107                 if (inoutbuf[0] & 0x80)
 108                         break;
 109         }
 110
 111         if (tries < 0) {
 112                 dev_err(&data->client->dev,
 113                         "mcp4725_store_eeprom() failed, incomplete\n");
 114                 return -EIO;
 115         }
 116
 117         return len;
 118 }
 119
 120 static IIO_DEVICE_ATTR(store_eeprom, S_IWUSR, NULL, mcp4725_store_eeprom, 0);
 121
 122 static struct attribute *mcp4725_attributes[] = {
 123         &iio_dev_attr_store_eeprom.dev_attr.attr,
 124         NULL,
 125 };
 126
 127 static const struct attribute_group mcp4725_attribute_group = {
 128         .attrs = mcp4725_attributes,
 129 };
 130
 131 static const char * const mcp4725_powerdown_modes[] = {
 132         "1kohm_to_gnd",
 133         "100kohm_to_gnd",
 134         "500kohm_to_gnd"
 135 };
 136
 137 static int mcp4725_get_powerdown_mode(struct iio_dev *indio_dev,
 138         const struct iio_chan_spec *chan)
 139 {
 140         struct mcp4725_data *data = iio_priv(indio_dev);
 141
 142         return data->powerdown_mode;
 143 }
 144
 145 static int mcp4725_set_powerdown_mode(struct iio_dev *indio_dev,
 146         const struct iio_chan_spec *chan, unsigned mode)
 147 {
 148         struct mcp4725_data *data = iio_priv(indio_dev);
 149
 150         data->powerdown_mode = mode;
 151
 152         return 0;
 153 }
 154
 155 static ssize_t mcp4725_read_powerdown(struct iio_dev *indio_dev,
 156         uintptr_t private, const struct iio_chan_spec *chan, char *buf)
 157 {
 158         struct mcp4725_data *data = iio_priv(indio_dev);
 159
 160         return sprintf(buf, "%d\n", data->powerdown);
 161 }
 162
 163 static ssize_t mcp4725_write_powerdown(struct iio_dev *indio_dev,
 164          uintptr_t private, const struct iio_chan_spec *chan,
 165          const char *buf, size_t len)
 166 {
 167         struct mcp4725_data *data = iio_priv(indio_dev);
 168         bool state;
 169         int ret;
 170
 171         ret = strtobool(buf, &state);
 172         if (ret)
 173                 return ret;
 174
 175         if (state)
 176                 ret = mcp4725_suspend(&data->client->dev);
 177         else
 178                 ret = mcp4725_resume(&data->client->dev);
 179         if (ret < 0)
 180                 return ret;
 181
 182         return len;
 183 }
 184
 185 static const struct iio_enum mcp4725_powerdown_mode_enum = {
 186         .items = mcp4725_powerdown_modes,
 187         .num_items = ARRAY_SIZE(mcp4725_powerdown_modes),
 188         .get = mcp4725_get_powerdown_mode,
 189         .set = mcp4725_set_powerdown_mode,
 190 };
 191
 192 static const struct iio_chan_spec_ext_info mcp4725_ext_info[] = {
 193         {
 194                 .name = "powerdown",
 195                 .read = mcp4725_read_powerdown,
 196                 .write = mcp4725_write_powerdown,
 197                 .shared = IIO_SEPARATE,
 198         },
 199         IIO_ENUM("powerdown_mode", IIO_SEPARATE, &mcp4725_powerdown_mode_enum),
 200         IIO_ENUM_AVAILABLE("powerdown_mode", &mcp4725_powerdown_mode_enum),
 201         { },
 202 };
 203
 204 static const struct iio_chan_spec mcp4725_channel = {
 205         .type           = IIO_VOLTAGE,
 206         .indexed        = 1,
 207         .output         = 1,
 208         .channel        = 0,
 209         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 210         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
 211         .ext_info       = mcp4725_ext_info,
 212 };
 213
 214 static int mcp4725_set_value(struct iio_dev *indio_dev, int val)
 215 {
 216         struct mcp4725_data *data = iio_priv(indio_dev);
 217         u8 outbuf[2];
 218         int ret;
 219
 220         if (val >= (1 << 12) || val < 0)
 221                 return -EINVAL;
 222
 223         outbuf[0] = (val >> 8) & 0xf;
 224         outbuf[1] = val & 0xff;
 225
 226         ret = i2c_master_send(data->client, outbuf, 2);
 227         if (ret < 0)
 228                 return ret;
 229         else if (ret != 2)
 230                 return -EIO;
 231         else
 232                 return 0;
 233 }
 234
 235 static int mcp4725_read_raw(struct iio_dev *indio_dev,
 236                            struct iio_chan_spec const *chan,
 237                            int *val, int *val2, long mask)
 238 {
 239         struct mcp4725_data *data = iio_priv(indio_dev);
 240
 241         switch (mask) {
 242         case IIO_CHAN_INFO_RAW:
 243                 *val = data->dac_value;
 244                 return IIO_VAL_INT;
 245         case IIO_CHAN_INFO_SCALE:
 246                 *val = data->vref_mv;
 247                 *val2 = 12;
 248                 return IIO_VAL_FRACTIONAL_LOG2;
 249         }
 250         return -EINVAL;
 251 }
 252
 253 static int mcp4725_write_raw(struct iio_dev *indio_dev,
 254                                struct iio_chan_spec const *chan,
 255                                int val, int val2, long mask)
 256 {
 257         struct mcp4725_data *data = iio_priv(indio_dev);
 258         int ret;
 259
 260         switch (mask) {
 261         case IIO_CHAN_INFO_RAW:
 262                 ret = mcp4725_set_value(indio_dev, val);
 263                 data->dac_value = val;
 264                 break;
 265         default:
 266                 ret = -EINVAL;
 267                 break;
 268         }
 269
 270         return ret;
 271 }
 272
 273 static const struct iio_info mcp4725_info = {
 274         .read_raw = mcp4725_read_raw,
 275         .write_raw = mcp4725_write_raw,
 276         .attrs = &mcp4725_attribute_group,
 277         .driver_module = THIS_MODULE,
 278 };
 279
 280 static int mcp4725_probe(struct i2c_client *client,
 281                          const struct i2c_device_id *id)
 282 {
 283         struct mcp4725_data *data;
 284         struct iio_dev *indio_dev;
 285         struct mcp4725_platform_data *platform_data = client->dev.platform_data;
 286         u8 inbuf[3];
 287         u8 pd;
 288         int err;
 289
 290         if (!platform_data || !platform_data->vref_mv) {
 291                 dev_err(&client->dev, "invalid platform data");
 292                 return -EINVAL;
 293         }
 294
 295         indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 296         if (indio_dev == NULL)
 297                 return -ENOMEM;
 298         data = iio_priv(indio_dev);
 299         i2c_set_clientdata(client, indio_dev);
 300         data->client = client;
 301
 302         indio_dev->dev.parent = &client->dev;
 303         indio_dev->info = &mcp4725_info;
 304         indio_dev->channels = &mcp4725_channel;
 305         indio_dev->num_channels = 1;
 306         indio_dev->modes = INDIO_DIRECT_MODE;
 307
 308         data->vref_mv = platform_data->vref_mv;
 309
 310         /* read current DAC value */
 311         err = i2c_master_recv(client, inbuf, 3);
 312         if (err < 0) {
 313                 dev_err(&client->dev, "failed to read DAC value");
 314                 return err;
 315         }
 316         pd = (inbuf[0] >> 1) & 0x3;
 317         data->powerdown = pd > 0 ? true : false;
 318         data->powerdown_mode = pd ? pd-1 : 2; /* 500kohm_to_gnd */
 319         data->dac_value = (inbuf[1] << 4) | (inbuf[2] >> 4);
 320
 321         return iio_device_register(indio_dev);
 322 }
 323
 324 static int mcp4725_remove(struct i2c_client *client)
 325 {
 326         iio_device_unregister(i2c_get_clientdata(client));
 327         return 0;
 328 }
 329
 330 static const struct i2c_device_id mcp4725_id[] = {
 331         { "mcp4725", 0 },
 332         { }
 333 };
 334 MODULE_DEVICE_TABLE(i2c, mcp4725_id);
 335
 336 static struct i2c_driver mcp4725_driver = {
 337         .driver = {
 338                 .name   = MCP4725_DRV_NAME,
 339                 .pm     = MCP4725_PM_OPS,
 340         },
 341         .probe          = mcp4725_probe,
 342         .remove         = mcp4725_remove,
 343         .id_table       = mcp4725_id,
 344 };
 345 module_i2c_driver(mcp4725_driver);
 346
 347 MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
 348 MODULE_DESCRIPTION("MCP4725 12-bit DAC");
 349 MODULE_LICENSE("GPL");