drivers/iio/dac/ltc2632.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * LTC2632 Digital to analog convertors spi driver
   4  *
   5  * Copyright 2017 Maxime Roussin-Bélanger
   6  * expanded by Silvan Murer <silvan.murer@gmail.com>
   7  */
   8
   9 #include <linux/device.h>
  10 #include <linux/spi/spi.h>
  11 #include <linux/module.h>
  12 #include <linux/iio/iio.h>
  13 #include <linux/regulator/consumer.h>
  14
  15 #define LTC2632_DAC_CHANNELS                    2
  16
  17 #define LTC2632_ADDR_DAC0                       0x0
  18 #define LTC2632_ADDR_DAC1                       0x1
  19
  20 #define LTC2632_CMD_WRITE_INPUT_N               0x0
  21 #define LTC2632_CMD_UPDATE_DAC_N                0x1
  22 #define LTC2632_CMD_WRITE_INPUT_N_UPDATE_ALL    0x2
  23 #define LTC2632_CMD_WRITE_INPUT_N_UPDATE_N      0x3
  24 #define LTC2632_CMD_POWERDOWN_DAC_N             0x4
  25 #define LTC2632_CMD_POWERDOWN_CHIP              0x5
  26 #define LTC2632_CMD_INTERNAL_REFER              0x6
  27 #define LTC2632_CMD_EXTERNAL_REFER              0x7
  28
  29 /**
  30  * struct ltc2632_chip_info - chip specific information
  31  * @channels:           channel spec for the DAC
  32  * @vref_mv:            internal reference voltage
  33  */
  34 struct ltc2632_chip_info {
  35         const struct iio_chan_spec *channels;
  36         const int vref_mv;
  37 };
  38
  39 /**
  40  * struct ltc2632_state - driver instance specific data
  41  * @spi_dev:                    pointer to the spi_device struct
  42  * @powerdown_cache_mask        used to show current channel powerdown state
  43  * @vref_mv                     used reference voltage (internal or external)
  44  * @vref_reg            regulator for the reference voltage
  45  */
  46 struct ltc2632_state {
  47         struct spi_device *spi_dev;
  48         unsigned int powerdown_cache_mask;
  49         int vref_mv;
  50         struct regulator *vref_reg;
  51 };
  52
  53 enum ltc2632_supported_device_ids {
  54         ID_LTC2632L12,
  55         ID_LTC2632L10,
  56         ID_LTC2632L8,
  57         ID_LTC2632H12,
  58         ID_LTC2632H10,
  59         ID_LTC2632H8,
  60 };
  61
  62 static int ltc2632_spi_write(struct spi_device *spi,
  63                              u8 cmd, u8 addr, u16 val, u8 shift)
  64 {
  65         u32 data;
  66         u8 msg[3];
  67
  68         /*
  69          * The input shift register is 24 bits wide.
  70          * The next four are the command bits, C3 to C0,
  71          * followed by the 4-bit DAC address, A3 to A0, and then the
  72          * 12-, 10-, 8-bit data-word. The data-word comprises the 12-,
  73          * 10-, 8-bit input code followed by 4, 6, or 8 don't care bits.
  74          */
  75         data = (cmd << 20) | (addr << 16) | (val << shift);
  76         msg[0] = data >> 16;
  77         msg[1] = data >> 8;
  78         msg[2] = data;
  79
  80         return spi_write(spi, msg, sizeof(msg));
  81 }
  82
  83 static int ltc2632_read_raw(struct iio_dev *indio_dev,
  84                             struct iio_chan_spec const *chan,
  85                             int *val,
  86                             int *val2,
  87                             long m)
  88 {
  89         const struct ltc2632_state *st = iio_priv(indio_dev);
  90
  91         switch (m) {
  92         case IIO_CHAN_INFO_SCALE:
  93                 *val = st->vref_mv;
  94                 *val2 = chan->scan_type.realbits;
  95                 return IIO_VAL_FRACTIONAL_LOG2;
  96         }
  97         return -EINVAL;
  98 }
  99
 100 static int ltc2632_write_raw(struct iio_dev *indio_dev,
 101                              struct iio_chan_spec const *chan,
 102                              int val,
 103                              int val2,
 104                              long mask)
 105 {
 106         struct ltc2632_state *st = iio_priv(indio_dev);
 107
 108         switch (mask) {
 109         case IIO_CHAN_INFO_RAW:
 110                 if (val >= (1 << chan->scan_type.realbits) || val < 0)
 111                         return -EINVAL;
 112
 113                 return ltc2632_spi_write(st->spi_dev,
 114                                          LTC2632_CMD_WRITE_INPUT_N_UPDATE_N,
 115                                          chan->address, val,
 116                                          chan->scan_type.shift);
 117         default:
 118                 return -EINVAL;
 119         }
 120 }
 121
 122 static ssize_t ltc2632_read_dac_powerdown(struct iio_dev *indio_dev,
 123                                           uintptr_t private,
 124                                           const struct iio_chan_spec *chan,
 125                                           char *buf)
 126 {
 127         struct ltc2632_state *st = iio_priv(indio_dev);
 128
 129         return sprintf(buf, "%d\n",
 130                        !!(st->powerdown_cache_mask & (1 << chan->channel)));
 131 }
 132
 133 static ssize_t ltc2632_write_dac_powerdown(struct iio_dev *indio_dev,
 134                                            uintptr_t private,
 135                                            const struct iio_chan_spec *chan,
 136                                            const char *buf,
 137                                            size_t len)
 138 {
 139         bool pwr_down;
 140         int ret;
 141         struct ltc2632_state *st = iio_priv(indio_dev);
 142
 143         ret = strtobool(buf, &pwr_down);
 144         if (ret)
 145                 return ret;
 146
 147         if (pwr_down)
 148                 st->powerdown_cache_mask |= (1 << chan->channel);
 149         else
 150                 st->powerdown_cache_mask &= ~(1 << chan->channel);
 151
 152         ret = ltc2632_spi_write(st->spi_dev,
 153                                 LTC2632_CMD_POWERDOWN_DAC_N,
 154                                 chan->channel, 0, 0);
 155
 156         return ret ? ret : len;
 157 }
 158
 159 static const struct iio_info ltc2632_info = {
 160         .write_raw      = ltc2632_write_raw,
 161         .read_raw       = ltc2632_read_raw,
 162 };
 163
 164 static const struct iio_chan_spec_ext_info ltc2632_ext_info[] = {
 165         {
 166                 .name = "powerdown",
 167                 .read = ltc2632_read_dac_powerdown,
 168                 .write = ltc2632_write_dac_powerdown,
 169                 .shared = IIO_SEPARATE,
 170         },
 171         { },
 172 };
 173
 174 #define LTC2632_CHANNEL(_chan, _bits) { \
 175                 .type = IIO_VOLTAGE, \
 176                 .indexed = 1, \
 177                 .output = 1, \
 178                 .channel = (_chan), \
 179                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
 180                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
 181                 .address = (_chan), \
 182                 .scan_type = { \
 183                         .realbits       = (_bits), \
 184                         .shift          = 16 - (_bits), \
 185                 }, \
 186                 .ext_info = ltc2632_ext_info, \
 187 }
 188
 189 #define DECLARE_LTC2632_CHANNELS(_name, _bits) \
 190         const struct iio_chan_spec _name ## _channels[] = { \
 191                 LTC2632_CHANNEL(0, _bits), \
 192                 LTC2632_CHANNEL(1, _bits), \
 193         }
 194
 195 static DECLARE_LTC2632_CHANNELS(ltc2632x12, 12);
 196 static DECLARE_LTC2632_CHANNELS(ltc2632x10, 10);
 197 static DECLARE_LTC2632_CHANNELS(ltc2632x8, 8);
 198
 199 static const struct ltc2632_chip_info ltc2632_chip_info_tbl[] = {
 200         [ID_LTC2632L12] = {
 201                 .channels       = ltc2632x12_channels,
 202                 .vref_mv        = 2500,
 203         },
 204         [ID_LTC2632L10] = {
 205                 .channels       = ltc2632x10_channels,
 206                 .vref_mv        = 2500,
 207         },
 208         [ID_LTC2632L8] =  {
 209                 .channels       = ltc2632x8_channels,
 210                 .vref_mv        = 2500,
 211         },
 212         [ID_LTC2632H12] = {
 213                 .channels       = ltc2632x12_channels,
 214                 .vref_mv        = 4096,
 215         },
 216         [ID_LTC2632H10] = {
 217                 .channels       = ltc2632x10_channels,
 218                 .vref_mv        = 4096,
 219         },
 220         [ID_LTC2632H8] =  {
 221                 .channels       = ltc2632x8_channels,
 222                 .vref_mv        = 4096,
 223         },
 224 };
 225
 226 static int ltc2632_probe(struct spi_device *spi)
 227 {
 228         struct ltc2632_state *st;
 229         struct iio_dev *indio_dev;
 230         struct ltc2632_chip_info *chip_info;
 231         int ret;
 232
 233         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 234         if (!indio_dev)
 235                 return -ENOMEM;
 236
 237         st = iio_priv(indio_dev);
 238
 239         spi_set_drvdata(spi, indio_dev);
 240         st->spi_dev = spi;
 241
 242         chip_info = (struct ltc2632_chip_info *)
 243                         spi_get_device_id(spi)->driver_data;
 244
 245         st->vref_reg = devm_regulator_get_optional(&spi->dev, "vref");
 246         if (PTR_ERR(st->vref_reg) == -ENODEV) {
 247                 /* use internal reference voltage */
 248                 st->vref_reg = NULL;
 249                 st->vref_mv = chip_info->vref_mv;
 250
 251                 ret = ltc2632_spi_write(spi, LTC2632_CMD_INTERNAL_REFER,
 252                                 0, 0, 0);
 253                 if (ret) {
 254                         dev_err(&spi->dev,
 255                                 "Set internal reference command failed, %d\n",
 256                                 ret);
 257                         return ret;
 258                 }
 259         } else if (IS_ERR(st->vref_reg)) {
 260                 dev_err(&spi->dev,
 261                                 "Error getting voltage reference regulator\n");
 262                 return PTR_ERR(st->vref_reg);
 263         } else {
 264                 /* use external reference voltage */
 265                 ret = regulator_enable(st->vref_reg);
 266                 if (ret) {
 267                         dev_err(&spi->dev,
 268                                 "enable reference regulator failed, %d\n",
 269                                 ret);
 270                         return ret;
 271                 }
 272                 st->vref_mv = regulator_get_voltage(st->vref_reg) / 1000;
 273
 274                 ret = ltc2632_spi_write(spi, LTC2632_CMD_EXTERNAL_REFER,
 275                                 0, 0, 0);
 276                 if (ret) {
 277                         dev_err(&spi->dev,
 278                                 "Set external reference command failed, %d\n",
 279                                 ret);
 280                         return ret;
 281                 }
 282         }
 283
 284         indio_dev->dev.parent = &spi->dev;
 285         indio_dev->name = dev_of_node(&spi->dev) ? dev_of_node(&spi->dev)->name
 286                                                  : spi_get_device_id(spi)->name;
 287         indio_dev->info = &ltc2632_info;
 288         indio_dev->modes = INDIO_DIRECT_MODE;
 289         indio_dev->channels = chip_info->channels;
 290         indio_dev->num_channels = LTC2632_DAC_CHANNELS;
 291
 292         return iio_device_register(indio_dev);
 293 }
 294
 295 static int ltc2632_remove(struct spi_device *spi)
 296 {
 297         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 298         struct ltc2632_state *st = iio_priv(indio_dev);
 299
 300         iio_device_unregister(indio_dev);
 301
 302         if (st->vref_reg)
 303                 regulator_disable(st->vref_reg);
 304
 305         return 0;
 306 }
 307
 308 static const struct spi_device_id ltc2632_id[] = {
 309         { "ltc2632-l12", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632L12] },
 310         { "ltc2632-l10", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632L10] },
 311         { "ltc2632-l8", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632L8] },
 312         { "ltc2632-h12", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632H12] },
 313         { "ltc2632-h10", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632H10] },
 314         { "ltc2632-h8", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632H8] },
 315         {}
 316 };
 317 MODULE_DEVICE_TABLE(spi, ltc2632_id);
 318
 319 static const struct of_device_id ltc2632_of_match[] = {
 320         {
 321                 .compatible = "lltc,ltc2632-l12",
 322                 .data = &ltc2632_chip_info_tbl[ID_LTC2632L12]
 323         }, {
 324                 .compatible = "lltc,ltc2632-l10",
 325                 .data = &ltc2632_chip_info_tbl[ID_LTC2632L10]
 326         }, {
 327                 .compatible = "lltc,ltc2632-l8",
 328                 .data = &ltc2632_chip_info_tbl[ID_LTC2632L8]
 329         }, {
 330                 .compatible = "lltc,ltc2632-h12",
 331                 .data = &ltc2632_chip_info_tbl[ID_LTC2632H12]
 332         }, {
 333                 .compatible = "lltc,ltc2632-h10",
 334                 .data = &ltc2632_chip_info_tbl[ID_LTC2632H10]
 335         }, {
 336                 .compatible = "lltc,ltc2632-h8",
 337                 .data = &ltc2632_chip_info_tbl[ID_LTC2632H8]
 338         },
 339         {}
 340 };
 341 MODULE_DEVICE_TABLE(of, ltc2632_of_match);
 342
 343 static struct spi_driver ltc2632_driver = {
 344         .driver         = {
 345                 .name   = "ltc2632",
 346                 .of_match_table = of_match_ptr(ltc2632_of_match),
 347         },
 348         .probe          = ltc2632_probe,
 349         .remove         = ltc2632_remove,
 350         .id_table       = ltc2632_id,
 351 };
 352 module_spi_driver(ltc2632_driver);
 353
 354 MODULE_AUTHOR("Maxime Roussin-Belanger <maxime.roussinbelanger@gmail.com>");
 355 MODULE_DESCRIPTION("LTC2632 DAC SPI driver");
 356 MODULE_LICENSE("GPL v2");