drivers/iio/adc/ti-tlc4541.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * TI tlc4541 ADC Driver
   4  *
   5  * Copyright (C) 2017 Phil Reid
   6  *
   7  * Datasheets can be found here:
   8  * https://www.ti.com/lit/gpn/tlc3541
   9  * https://www.ti.com/lit/gpn/tlc4541
  10  *
  11  * The tlc4541 requires 24 clock cycles to start a transfer.
  12  * Conversion then takes 2.94us to complete before data is ready
  13  * Data is returned MSB first.
  14  */
  15
  16 #include <linux/delay.h>
  17 #include <linux/device.h>
  18 #include <linux/err.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/iio/iio.h>
  21 #include <linux/iio/sysfs.h>
  22 #include <linux/iio/buffer.h>
  23 #include <linux/iio/trigger_consumer.h>
  24 #include <linux/iio/triggered_buffer.h>
  25 #include <linux/kernel.h>
  26 #include <linux/module.h>
  27 #include <linux/mod_devicetable.h>
  28 #include <linux/regulator/consumer.h>
  29 #include <linux/slab.h>
  30 #include <linux/spi/spi.h>
  31 #include <linux/sysfs.h>
  32
  33 struct tlc4541_state {
  34         struct spi_device               *spi;
  35         struct regulator                *reg;
  36         struct spi_transfer             scan_single_xfer[3];
  37         struct spi_message              scan_single_msg;
  38
  39         /*
  40          * DMA (thus cache coherency maintenance) requires the
  41          * transfer buffers to live in their own cache lines.
  42          * 2 bytes data + 6 bytes padding + 8 bytes timestamp when
  43          * call iio_push_to_buffers_with_timestamp.
  44          */
  45         __be16                          rx_buf[8] ____cacheline_aligned;
  46 };
  47
  48 struct tlc4541_chip_info {
  49         const struct iio_chan_spec *channels;
  50         unsigned int num_channels;
  51 };
  52
  53 enum tlc4541_id {
  54         TLC3541,
  55         TLC4541,
  56 };
  57
  58 #define TLC4541_V_CHAN(bits, bitshift) {                              \
  59                 .type = IIO_VOLTAGE,                                  \
  60                 .info_mask_separate       = BIT(IIO_CHAN_INFO_RAW),   \
  61                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
  62                 .scan_type = {                                        \
  63                         .sign = 'u',                                  \
  64                         .realbits = (bits),                           \
  65                         .storagebits = 16,                            \
  66                         .shift = (bitshift),                          \
  67                         .endianness = IIO_BE,                         \
  68                 },                                                    \
  69         }
  70
  71 #define DECLARE_TLC4541_CHANNELS(name, bits, bitshift) \
  72 const struct iio_chan_spec name ## _channels[] = { \
  73         TLC4541_V_CHAN(bits, bitshift), \
  74         IIO_CHAN_SOFT_TIMESTAMP(1), \
  75 }
  76
  77 static DECLARE_TLC4541_CHANNELS(tlc3541, 14, 2);
  78 static DECLARE_TLC4541_CHANNELS(tlc4541, 16, 0);
  79
  80 static const struct tlc4541_chip_info tlc4541_chip_info[] = {
  81         [TLC3541] = {
  82                 .channels = tlc3541_channels,
  83                 .num_channels = ARRAY_SIZE(tlc3541_channels),
  84         },
  85         [TLC4541] = {
  86                 .channels = tlc4541_channels,
  87                 .num_channels = ARRAY_SIZE(tlc4541_channels),
  88         },
  89 };
  90
  91 static irqreturn_t tlc4541_trigger_handler(int irq, void *p)
  92 {
  93         struct iio_poll_func *pf = p;
  94         struct iio_dev *indio_dev = pf->indio_dev;
  95         struct tlc4541_state *st = iio_priv(indio_dev);
  96         int ret;
  97
  98         ret = spi_sync(st->spi, &st->scan_single_msg);
  99         if (ret < 0)
 100                 goto done;
 101
 102         iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
 103                                            iio_get_time_ns(indio_dev));
 104
 105 done:
 106         iio_trigger_notify_done(indio_dev->trig);
 107         return IRQ_HANDLED;
 108 }
 109
 110 static int tlc4541_get_range(struct tlc4541_state *st)
 111 {
 112         int vref;
 113
 114         vref = regulator_get_voltage(st->reg);
 115         if (vref < 0)
 116                 return vref;
 117
 118         vref /= 1000;
 119
 120         return vref;
 121 }
 122
 123 static int tlc4541_read_raw(struct iio_dev *indio_dev,
 124                             struct iio_chan_spec const *chan,
 125                             int *val,
 126                             int *val2,
 127                             long m)
 128 {
 129         int ret = 0;
 130         struct tlc4541_state *st = iio_priv(indio_dev);
 131
 132         switch (m) {
 133         case IIO_CHAN_INFO_RAW:
 134                 ret = iio_device_claim_direct_mode(indio_dev);
 135                 if (ret)
 136                         return ret;
 137                 ret = spi_sync(st->spi, &st->scan_single_msg);
 138                 iio_device_release_direct_mode(indio_dev);
 139                 if (ret < 0)
 140                         return ret;
 141                 *val = be16_to_cpu(st->rx_buf[0]);
 142                 *val = *val >> chan->scan_type.shift;
 143                 *val &= GENMASK(chan->scan_type.realbits - 1, 0);
 144                 return IIO_VAL_INT;
 145         case IIO_CHAN_INFO_SCALE:
 146                 ret = tlc4541_get_range(st);
 147                 if (ret < 0)
 148                         return ret;
 149                 *val = ret;
 150                 *val2 = chan->scan_type.realbits;
 151                 return IIO_VAL_FRACTIONAL_LOG2;
 152         }
 153         return -EINVAL;
 154 }
 155
 156 static const struct iio_info tlc4541_info = {
 157         .read_raw = &tlc4541_read_raw,
 158 };
 159
 160 static int tlc4541_probe(struct spi_device *spi)
 161 {
 162         struct tlc4541_state *st;
 163         struct iio_dev *indio_dev;
 164         const struct tlc4541_chip_info *info;
 165         int ret;
 166         int8_t device_init = 0;
 167
 168         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 169         if (indio_dev == NULL)
 170                 return -ENOMEM;
 171
 172         st = iio_priv(indio_dev);
 173
 174         spi_set_drvdata(spi, indio_dev);
 175
 176         st->spi = spi;
 177
 178         info = &tlc4541_chip_info[spi_get_device_id(spi)->driver_data];
 179
 180         indio_dev->name = spi_get_device_id(spi)->name;
 181         indio_dev->modes = INDIO_DIRECT_MODE;
 182         indio_dev->channels = info->channels;
 183         indio_dev->num_channels = info->num_channels;
 184         indio_dev->info = &tlc4541_info;
 185
 186         /* perform reset */
 187         spi_write(spi, &device_init, 1);
 188
 189         /* Setup default message */
 190         st->scan_single_xfer[0].rx_buf = &st->rx_buf[0];
 191         st->scan_single_xfer[0].len = 3;
 192         st->scan_single_xfer[1].delay.value = 3;
 193         st->scan_single_xfer[1].delay.unit = SPI_DELAY_UNIT_NSECS;
 194         st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
 195         st->scan_single_xfer[2].len = 2;
 196
 197         spi_message_init_with_transfers(&st->scan_single_msg,
 198                                         st->scan_single_xfer, 3);
 199
 200         st->reg = devm_regulator_get(&spi->dev, "vref");
 201         if (IS_ERR(st->reg))
 202                 return PTR_ERR(st->reg);
 203
 204         ret = regulator_enable(st->reg);
 205         if (ret)
 206                 return ret;
 207
 208         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 209                         &tlc4541_trigger_handler, NULL);
 210         if (ret)
 211                 goto error_disable_reg;
 212
 213         ret = iio_device_register(indio_dev);
 214         if (ret)
 215                 goto error_cleanup_buffer;
 216
 217         return 0;
 218
 219 error_cleanup_buffer:
 220         iio_triggered_buffer_cleanup(indio_dev);
 221 error_disable_reg:
 222         regulator_disable(st->reg);
 223
 224         return ret;
 225 }
 226
 227 static int tlc4541_remove(struct spi_device *spi)
 228 {
 229         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 230         struct tlc4541_state *st = iio_priv(indio_dev);
 231
 232         iio_device_unregister(indio_dev);
 233         iio_triggered_buffer_cleanup(indio_dev);
 234         regulator_disable(st->reg);
 235
 236         return 0;
 237 }
 238
 239 static const struct of_device_id tlc4541_dt_ids[] = {
 240         { .compatible = "ti,tlc3541", },
 241         { .compatible = "ti,tlc4541", },
 242         {}
 243 };
 244 MODULE_DEVICE_TABLE(of, tlc4541_dt_ids);
 245
 246 static const struct spi_device_id tlc4541_id[] = {
 247         {"tlc3541", TLC3541},
 248         {"tlc4541", TLC4541},
 249         {}
 250 };
 251 MODULE_DEVICE_TABLE(spi, tlc4541_id);
 252
 253 static struct spi_driver tlc4541_driver = {
 254         .driver = {
 255                 .name   = "tlc4541",
 256                 .of_match_table = tlc4541_dt_ids,
 257         },
 258         .probe          = tlc4541_probe,
 259         .remove         = tlc4541_remove,
 260         .id_table       = tlc4541_id,
 261 };
 262 module_spi_driver(tlc4541_driver);
 263
 264 MODULE_AUTHOR("Phil Reid <preid@electromag.com.au>");
 265 MODULE_DESCRIPTION("Texas Instruments TLC4541 ADC");
 266 MODULE_LICENSE("GPL v2");