drivers/iio/dac/ltc2632.c

   1 /*
   2  * LTC2632 Digital to analog convertors spi driver
   3  *
   4  * Copyright 2017 Maxime Roussin-Bélanger
   5  *
   6  * Licensed under the GPL-2.
   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
  14 #define LTC2632_DAC_CHANNELS                    2
  15
  16 #define LTC2632_ADDR_DAC0                       0x0
  17 #define LTC2632_ADDR_DAC1                       0x1
  18
  19 #define LTC2632_CMD_WRITE_INPUT_N               0x0
  20 #define LTC2632_CMD_UPDATE_DAC_N                0x1
  21 #define LTC2632_CMD_WRITE_INPUT_N_UPDATE_ALL    0x2
  22 #define LTC2632_CMD_WRITE_INPUT_N_UPDATE_N      0x3
  23 #define LTC2632_CMD_POWERDOWN_DAC_N             0x4
  24 #define LTC2632_CMD_POWERDOWN_CHIP              0x5
  25 #define LTC2632_CMD_INTERNAL_REFER              0x6
  26 #define LTC2632_CMD_EXTERNAL_REFER              0x7
  27
  28 /**
  29  * struct ltc2632_chip_info - chip specific information
  30  * @channels:           channel spec for the DAC
  31  * @vref_mv:            reference voltage
  32  */
  33 struct ltc2632_chip_info {
  34         const struct iio_chan_spec *channels;
  35         const int vref_mv;
  36 };
  37
  38 /**
  39  * struct ltc2632_state - driver instance specific data
  40  * @spi_dev:                    pointer to the spi_device struct
  41  * @powerdown_cache_mask        used to show current channel powerdown state
  42  */
  43 struct ltc2632_state {
  44         struct spi_device *spi_dev;
  45         unsigned int powerdown_cache_mask;
  46 };
  47
  48 enum ltc2632_supported_device_ids {
  49         ID_LTC2632L12,
  50         ID_LTC2632L10,
  51         ID_LTC2632L8,
  52         ID_LTC2632H12,
  53         ID_LTC2632H10,
  54         ID_LTC2632H8,
  55 };
  56
  57 static int ltc2632_spi_write(struct spi_device *spi,
  58                              u8 cmd, u8 addr, u16 val, u8 shift)
  59 {
  60         u32 data;
  61         u8 msg[3];
  62
  63         /*
  64          * The input shift register is 24 bits wide.
  65          * The next four are the command bits, C3 to C0,
  66          * followed by the 4-bit DAC address, A3 to A0, and then the
  67          * 12-, 10-, 8-bit data-word. The data-word comprises the 12-,
  68          * 10-, 8-bit input code followed by 4, 6, or 8 don't care bits.
  69          */
  70         data = (cmd << 20) | (addr << 16) | (val << shift);
  71         msg[0] = data >> 16;
  72         msg[1] = data >> 8;
  73         msg[2] = data;
  74
  75         return spi_write(spi, msg, sizeof(msg));
  76 }
  77
  78 static int ltc2632_read_raw(struct iio_dev *indio_dev,
  79                             struct iio_chan_spec const *chan,
  80                             int *val,
  81                             int *val2,
  82                             long m)
  83 {
  84         struct ltc2632_chip_info *chip_info;
  85
  86         const struct ltc2632_state *st = iio_priv(indio_dev);
  87         const struct spi_device_id *spi_dev_id = spi_get_device_id(st->spi_dev);
  88
  89         chip_info = (struct ltc2632_chip_info *)spi_dev_id->driver_data;
  90
  91         switch (m) {
  92         case IIO_CHAN_INFO_SCALE:
  93                 *val = chip_info->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         .driver_module  = THIS_MODULE,
 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         indio_dev->dev.parent = &spi->dev;
 251         indio_dev->name = dev_of_node(&spi->dev) ? dev_of_node(&spi->dev)->name
 252                                                  : spi_get_device_id(spi)->name;
 253         indio_dev->info = &ltc2632_info;
 254         indio_dev->modes = INDIO_DIRECT_MODE;
 255         indio_dev->channels = chip_info->channels;
 256         indio_dev->num_channels = LTC2632_DAC_CHANNELS;
 257
 258         ret = ltc2632_spi_write(spi, LTC2632_CMD_INTERNAL_REFER, 0, 0, 0);
 259         if (ret) {
 260                 dev_err(&spi->dev,
 261                         "Set internal reference command failed, %d\n", ret);
 262                 return ret;
 263         }
 264
 265         return devm_iio_device_register(&spi->dev, indio_dev);
 266 }
 267
 268 static const struct spi_device_id ltc2632_id[] = {
 269         { "ltc2632-l12", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632L12] },
 270         { "ltc2632-l10", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632L10] },
 271         { "ltc2632-l8", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632L8] },
 272         { "ltc2632-h12", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632H12] },
 273         { "ltc2632-h10", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632H10] },
 274         { "ltc2632-h8", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632H8] },
 275         {}
 276 };
 277 MODULE_DEVICE_TABLE(spi, ltc2632_id);
 278
 279 static struct spi_driver ltc2632_driver = {
 280         .driver         = {
 281                 .name   = "ltc2632",
 282         },
 283         .probe          = ltc2632_probe,
 284         .id_table       = ltc2632_id,
 285 };
 286 module_spi_driver(ltc2632_driver);
 287
 288 static const struct of_device_id ltc2632_of_match[] = {
 289         {
 290                 .compatible = "lltc,ltc2632-l12",
 291                 .data = &ltc2632_chip_info_tbl[ID_LTC2632L12]
 292         }, {
 293                 .compatible = "lltc,ltc2632-l10",
 294                 .data = &ltc2632_chip_info_tbl[ID_LTC2632L10]
 295         }, {
 296                 .compatible = "lltc,ltc2632-l8",
 297                 .data = &ltc2632_chip_info_tbl[ID_LTC2632L8]
 298         }, {
 299                 .compatible = "lltc,ltc2632-h12",
 300                 .data = &ltc2632_chip_info_tbl[ID_LTC2632H12]
 301         }, {
 302                 .compatible = "lltc,ltc2632-h10",
 303                 .data = &ltc2632_chip_info_tbl[ID_LTC2632H10]
 304         }, {
 305                 .compatible = "lltc,ltc2632-h8",
 306                 .data = &ltc2632_chip_info_tbl[ID_LTC2632H8]
 307         },
 308         {}
 309 };
 310 MODULE_DEVICE_TABLE(of, ltc2632_of_match);
 311
 312 MODULE_AUTHOR("Maxime Roussin-Belanger <maxime.roussinbelanger@gmail.com>");
 313 MODULE_DESCRIPTION("LTC2632 DAC SPI driver");
 314 MODULE_LICENSE("GPL v2");