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