drivers/iio/dac/ltc2632.c

   1 /*
   2  * LTC2632 Digital to analog convertors spi driver
   3  *
   4  * Copyright 2017 Maxime Roussin-Bélanger
   5  * expanded by Silvan Murer <silvan.murer@gmail.com>
   6  *
   7  * Licensed under the GPL-2.
   8  */
   9
  10 #include <linux/device.h>
  11 #include <linux/spi/spi.h>
  12 #include <linux/module.h>
  13 #include <linux/iio/iio.h>
  14 #include <linux/regulator/consumer.h>
  15
  16 #define LTC2632_DAC_CHANNELS                    2
  17
  18 #define LTC2632_ADDR_DAC0                       0x0
  19 #define LTC2632_ADDR_DAC1                       0x1
  20
  21 #define LTC2632_CMD_WRITE_INPUT_N               0x0
  22 #define LTC2632_CMD_UPDATE_DAC_N                0x1
  23 #define LTC2632_CMD_WRITE_INPUT_N_UPDATE_ALL    0x2
  24 #define LTC2632_CMD_WRITE_INPUT_N_UPDATE_N      0x3
  25 #define LTC2632_CMD_POWERDOWN_DAC_N             0x4
  26 #define LTC2632_CMD_POWERDOWN_CHIP              0x5
  27 #define LTC2632_CMD_INTERNAL_REFER              0x6
  28 #define LTC2632_CMD_EXTERNAL_REFER              0x7
  29
  30 /**
  31  * struct ltc2632_chip_info - chip specific information
  32  * @channels:           channel spec for the DAC
  33  * @vref_mv:            internal reference voltage
  34  */
  35 struct ltc2632_chip_info {
  36         const struct iio_chan_spec *channels;
  37         const int vref_mv;
  38 };
  39
  40 /**
  41  * struct ltc2632_state - driver instance specific data
  42  * @spi_dev:                    pointer to the spi_device struct
  43  * @powerdown_cache_mask        used to show current channel powerdown state
  44  * @vref_mv                     used reference voltage (internal or external)
  45  * @vref_reg            regulator for the reference voltage
  46  */
  47 struct ltc2632_state {
  48         struct spi_device *spi_dev;
  49         unsigned int powerdown_cache_mask;
  50         int vref_mv;
  51         struct regulator *vref_reg;
  52 };
  53
  54 enum ltc2632_supported_device_ids {
  55         ID_LTC2632L12,
  56         ID_LTC2632L10,
  57         ID_LTC2632L8,
  58         ID_LTC2632H12,
  59         ID_LTC2632H10,
  60         ID_LTC2632H8,
  61 };
  62
  63 static int ltc2632_spi_write(struct spi_device *spi,
  64                              u8 cmd, u8 addr, u16 val, u8 shift)
  65 {
  66         u32 data;
  67         u8 msg[3];
  68
  69         /*
  70          * The input shift register is 24 bits wide.
  71          * The next four are the command bits, C3 to C0,
  72          * followed by the 4-bit DAC address, A3 to A0, and then the
  73          * 12-, 10-, 8-bit data-word. The data-word comprises the 12-,
  74          * 10-, 8-bit input code followed by 4, 6, or 8 don't care bits.
  75          */
  76         data = (cmd << 20) | (addr << 16) | (val << shift);
  77         msg[0] = data >> 16;
  78         msg[1] = data >> 8;
  79         msg[2] = data;
  80
  81         return spi_write(spi, msg, sizeof(msg));
  82 }
  83
  84 static int ltc2632_read_raw(struct iio_dev *indio_dev,
  85                             struct iio_chan_spec const *chan,
  86                             int *val,
  87                             int *val2,
  88                             long m)
  89 {
  90         const struct ltc2632_state *st = iio_priv(indio_dev);
  91
  92         switch (m) {
  93         case IIO_CHAN_INFO_SCALE:
  94                 *val = st->vref_mv;
  95                 *val2 = chan->scan_type.realbits;
  96                 return IIO_VAL_FRACTIONAL_LOG2;
  97         }
  98         return -EINVAL;
  99 }
 100
 101 static int ltc2632_write_raw(struct iio_dev *indio_dev,
 102                              struct iio_chan_spec const *chan,
 103                              int val,
 104                              int val2,
 105                              long mask)
 106 {
 107         struct ltc2632_state *st = iio_priv(indio_dev);
 108
 109         switch (mask) {
 110         case IIO_CHAN_INFO_RAW:
 111                 if (val >= (1 << chan->scan_type.realbits) || val < 0)
 112                         return -EINVAL;
 113
 114                 return ltc2632_spi_write(st->spi_dev,
 115                                          LTC2632_CMD_WRITE_INPUT_N_UPDATE_N,
 116                                          chan->address, val,
 117                                          chan->scan_type.shift);
 118         default:
 119                 return -EINVAL;
 120         }
 121 }
 122
 123 static ssize_t ltc2632_read_dac_powerdown(struct iio_dev *indio_dev,
 124                                           uintptr_t private,
 125                                           const struct iio_chan_spec *chan,
 126                                           char *buf)
 127 {
 128         struct ltc2632_state *st = iio_priv(indio_dev);
 129
 130         return sprintf(buf, "%d\n",
 131                        !!(st->powerdown_cache_mask & (1 << chan->channel)));
 132 }
 133
 134 static ssize_t ltc2632_write_dac_powerdown(struct iio_dev *indio_dev,
 135                                            uintptr_t private,
 136                                            const struct iio_chan_spec *chan,
 137                                            const char *buf,
 138                                            size_t len)
 139 {
 140         bool pwr_down;
 141         int ret;
 142         struct ltc2632_state *st = iio_priv(indio_dev);
 143
 144         ret = strtobool(buf, &pwr_down);
 145         if (ret)
 146                 return ret;
 147
 148         if (pwr_down)
 149                 st->powerdown_cache_mask |= (1 << chan->channel);
 150         else
 151                 st->powerdown_cache_mask &= ~(1 << chan->channel);
 152
 153         ret = ltc2632_spi_write(st->spi_dev,
 154                                 LTC2632_CMD_POWERDOWN_DAC_N,
 155                                 chan->channel, 0, 0);
 156
 157         return ret ? ret : len;
 158 }
 159
 160 static const struct iio_info ltc2632_info = {
 161         .write_raw      = ltc2632_write_raw,
 162         .read_raw       = ltc2632_read_raw,
 163 };
 164
 165 static const struct iio_chan_spec_ext_info ltc2632_ext_info[] = {
 166         {
 167                 .name = "powerdown",
 168                 .read = ltc2632_read_dac_powerdown,
 169                 .write = ltc2632_write_dac_powerdown,
 170                 .shared = IIO_SEPARATE,
 171         },
 172         { },
 173 };
 174
 175 #define LTC2632_CHANNEL(_chan, _bits) { \
 176                 .type = IIO_VOLTAGE, \
 177                 .indexed = 1, \
 178                 .output = 1, \
 179                 .channel = (_chan), \
 180                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
 181                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
 182                 .address = (_chan), \
 183                 .scan_type = { \
 184                         .realbits       = (_bits), \
 185                         .shift          = 16 - (_bits), \
 186                 }, \
 187                 .ext_info = ltc2632_ext_info, \
 188 }
 189
 190 #define DECLARE_LTC2632_CHANNELS(_name, _bits) \
 191         const struct iio_chan_spec _name ## _channels[] = { \
 192                 LTC2632_CHANNEL(0, _bits), \
 193                 LTC2632_CHANNEL(1, _bits), \
 194         }
 195
 196 static DECLARE_LTC2632_CHANNELS(ltc2632l12, 12);
 197 static DECLARE_LTC2632_CHANNELS(ltc2632l10, 10);
 198 static DECLARE_LTC2632_CHANNELS(ltc2632l8, 8);
 199
 200 static DECLARE_LTC2632_CHANNELS(ltc2632h12, 12);
 201 static DECLARE_LTC2632_CHANNELS(ltc2632h10, 10);
 202 static DECLARE_LTC2632_CHANNELS(ltc2632h8, 8);
 203
 204 static const struct ltc2632_chip_info ltc2632_chip_info_tbl[] = {
 205         [ID_LTC2632L12] = {
 206                 .channels       = ltc2632l12_channels,
 207                 .vref_mv        = 2500,
 208         },
 209         [ID_LTC2632L10] = {
 210                 .channels       = ltc2632l10_channels,
 211                 .vref_mv        = 2500,
 212         },
 213         [ID_LTC2632L8] =  {
 214                 .channels       = ltc2632l8_channels,
 215                 .vref_mv        = 2500,
 216         },
 217         [ID_LTC2632H12] = {
 218                 .channels       = ltc2632h12_channels,
 219                 .vref_mv        = 4096,
 220         },
 221         [ID_LTC2632H10] = {
 222                 .channels       = ltc2632h10_channels,
 223                 .vref_mv        = 4096,
 224         },
 225         [ID_LTC2632H8] =  {
 226                 .channels       = ltc2632h8_channels,
 227                 .vref_mv        = 4096,
 228         },
 229 };
 230
 231 static int ltc2632_probe(struct spi_device *spi)
 232 {
 233         struct ltc2632_state *st;
 234         struct iio_dev *indio_dev;
 235         struct ltc2632_chip_info *chip_info;
 236         int ret;
 237
 238         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 239         if (!indio_dev)
 240                 return -ENOMEM;
 241
 242         st = iio_priv(indio_dev);
 243
 244         spi_set_drvdata(spi, indio_dev);
 245         st->spi_dev = spi;
 246
 247         chip_info = (struct ltc2632_chip_info *)
 248                         spi_get_device_id(spi)->driver_data;
 249
 250         st->vref_reg = devm_regulator_get_optional(&spi->dev, "vref");
 251         if (PTR_ERR(st->vref_reg) == -ENODEV) {
 252                 /* use internal reference voltage */
 253                 st->vref_reg = NULL;
 254                 st->vref_mv = chip_info->vref_mv;
 255
 256                 ret = ltc2632_spi_write(spi, LTC2632_CMD_INTERNAL_REFER,
 257                                 0, 0, 0);
 258                 if (ret) {
 259                         dev_err(&spi->dev,
 260                                 "Set internal reference command failed, %d\n",
 261                                 ret);
 262                         return ret;
 263                 }
 264         } else if (IS_ERR(st->vref_reg)) {
 265                 dev_err(&spi->dev,
 266                                 "Error getting voltage reference regulator\n");
 267                 return PTR_ERR(st->vref_reg);
 268         } else {
 269                 /* use external reference voltage */
 270                 ret = regulator_enable(st->vref_reg);
 271                 if (ret) {
 272                         dev_err(&spi->dev,
 273                                 "enable reference regulator failed, %d\n",
 274                                 ret);
 275                         return ret;
 276                 }
 277                 st->vref_mv = regulator_get_voltage(st->vref_reg) / 1000;
 278
 279                 ret = ltc2632_spi_write(spi, LTC2632_CMD_EXTERNAL_REFER,
 280                                 0, 0, 0);
 281                 if (ret) {
 282                         dev_err(&spi->dev,
 283                                 "Set external reference command failed, %d\n",
 284                                 ret);
 285                         return ret;
 286                 }
 287         }
 288
 289         indio_dev->dev.parent = &spi->dev;
 290         indio_dev->name = dev_of_node(&spi->dev) ? dev_of_node(&spi->dev)->name
 291                                                  : spi_get_device_id(spi)->name;
 292         indio_dev->info = &ltc2632_info;
 293         indio_dev->modes = INDIO_DIRECT_MODE;
 294         indio_dev->channels = chip_info->channels;
 295         indio_dev->num_channels = LTC2632_DAC_CHANNELS;
 296
 297         return iio_device_register(indio_dev);
 298 }
 299
 300 static int ltc2632_remove(struct spi_device *spi)
 301 {
 302         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 303         struct ltc2632_state *st = iio_priv(indio_dev);
 304
 305         iio_device_unregister(indio_dev);
 306
 307         if (st->vref_reg)
 308                 regulator_disable(st->vref_reg);
 309
 310         return 0;
 311 }
 312
 313 static const struct spi_device_id ltc2632_id[] = {
 314         { "ltc2632-l12", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632L12] },
 315         { "ltc2632-l10", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632L10] },
 316         { "ltc2632-l8", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632L8] },
 317         { "ltc2632-h12", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632H12] },
 318         { "ltc2632-h10", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632H10] },
 319         { "ltc2632-h8", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632H8] },
 320         {}
 321 };
 322 MODULE_DEVICE_TABLE(spi, ltc2632_id);
 323
 324 static const struct of_device_id ltc2632_of_match[] = {
 325         {
 326                 .compatible = "lltc,ltc2632-l12",
 327                 .data = &ltc2632_chip_info_tbl[ID_LTC2632L12]
 328         }, {
 329                 .compatible = "lltc,ltc2632-l10",
 330                 .data = &ltc2632_chip_info_tbl[ID_LTC2632L10]
 331         }, {
 332                 .compatible = "lltc,ltc2632-l8",
 333                 .data = &ltc2632_chip_info_tbl[ID_LTC2632L8]
 334         }, {
 335                 .compatible = "lltc,ltc2632-h12",
 336                 .data = &ltc2632_chip_info_tbl[ID_LTC2632H12]
 337         }, {
 338                 .compatible = "lltc,ltc2632-h10",
 339                 .data = &ltc2632_chip_info_tbl[ID_LTC2632H10]
 340         }, {
 341                 .compatible = "lltc,ltc2632-h8",
 342                 .data = &ltc2632_chip_info_tbl[ID_LTC2632H8]
 343         },
 344         {}
 345 };
 346 MODULE_DEVICE_TABLE(of, ltc2632_of_match);
 347
 348 static struct spi_driver ltc2632_driver = {
 349         .driver         = {
 350                 .name   = "ltc2632",
 351                 .of_match_table = of_match_ptr(ltc2632_of_match),
 352         },
 353         .probe          = ltc2632_probe,
 354         .remove         = ltc2632_remove,
 355         .id_table       = ltc2632_id,
 356 };
 357 module_spi_driver(ltc2632_driver);
 358
 359 MODULE_AUTHOR("Maxime Roussin-Belanger <maxime.roussinbelanger@gmail.com>");
 360 MODULE_DESCRIPTION("LTC2632 DAC SPI driver");
 361 MODULE_LICENSE("GPL v2");