drivers/iio/adc/ti-tlc4541.c

   1 /*
   2  * TI tlc4541 ADC Driver
   3  *
   4  * Copyright (C) 2017 Phil Reid
   5  *
   6  * Datasheets can be found here:
   7  * http://www.ti.com/lit/gpn/tlc3541
   8  * http://www.ti.com/lit/gpn/tlc4541
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  *
  14  * The tlc4541 requires 24 clock cycles to start a transfer.
  15  * Conversion then takes 2.94us to complete before data is ready
  16  * Data is returned MSB first.
  17  */
  18
  19 #include <linux/delay.h>
  20 #include <linux/device.h>
  21 #include <linux/err.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/iio/iio.h>
  24 #include <linux/iio/sysfs.h>
  25 #include <linux/iio/buffer.h>
  26 #include <linux/iio/trigger_consumer.h>
  27 #include <linux/iio/triggered_buffer.h>
  28 #include <linux/kernel.h>
  29 #include <linux/module.h>
  30 #include <linux/regulator/consumer.h>
  31 #include <linux/slab.h>
  32 #include <linux/spi/spi.h>
  33 #include <linux/sysfs.h>
  34
  35 struct tlc4541_state {
  36         struct spi_device               *spi;
  37         struct regulator                *reg;
  38         struct spi_transfer             scan_single_xfer[3];
  39         struct spi_message              scan_single_msg;
  40
  41         /*
  42          * DMA (thus cache coherency maintenance) requires the
  43          * transfer buffers to live in their own cache lines.
  44          * 2 bytes data + 6 bytes padding + 8 bytes timestamp when
  45          * call iio_push_to_buffers_with_timestamp.
  46          */
  47         __be16                          rx_buf[8] ____cacheline_aligned;
  48 };
  49
  50 struct tlc4541_chip_info {
  51         const struct iio_chan_spec *channels;
  52         unsigned int num_channels;
  53 };
  54
  55 enum tlc4541_id {
  56         TLC3541,
  57         TLC4541,
  58 };
  59
  60 #define TLC4541_V_CHAN(bits, bitshift) {                              \
  61                 .type = IIO_VOLTAGE,                                  \
  62                 .info_mask_separate       = BIT(IIO_CHAN_INFO_RAW),   \
  63                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
  64                 .scan_type = {                                        \
  65                         .sign = 'u',                                  \
  66                         .realbits = (bits),                           \
  67                         .storagebits = 16,                            \
  68                         .shift = (bitshift),                          \
  69                         .endianness = IIO_BE,                         \
  70                 },                                                    \
  71         }
  72
  73 #define DECLARE_TLC4541_CHANNELS(name, bits, bitshift) \
  74 const struct iio_chan_spec name ## _channels[] = { \
  75         TLC4541_V_CHAN(bits, bitshift), \
  76         IIO_CHAN_SOFT_TIMESTAMP(1), \
  77 }
  78
  79 static DECLARE_TLC4541_CHANNELS(tlc3541, 14, 2);
  80 static DECLARE_TLC4541_CHANNELS(tlc4541, 16, 0);
  81
  82 static const struct tlc4541_chip_info tlc4541_chip_info[] = {
  83         [TLC3541] = {
  84                 .channels = tlc3541_channels,
  85                 .num_channels = ARRAY_SIZE(tlc3541_channels),
  86         },
  87         [TLC4541] = {
  88                 .channels = tlc4541_channels,
  89                 .num_channels = ARRAY_SIZE(tlc4541_channels),
  90         },
  91 };
  92
  93 static irqreturn_t tlc4541_trigger_handler(int irq, void *p)
  94 {
  95         struct iio_poll_func *pf = p;
  96         struct iio_dev *indio_dev = pf->indio_dev;
  97         struct tlc4541_state *st = iio_priv(indio_dev);
  98         int ret;
  99
 100         ret = spi_sync(st->spi, &st->scan_single_msg);
 101         if (ret < 0)
 102                 goto done;
 103
 104         iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
 105                                            iio_get_time_ns(indio_dev));
 106
 107 done:
 108         iio_trigger_notify_done(indio_dev->trig);
 109         return IRQ_HANDLED;
 110 }
 111
 112 static int tlc4541_get_range(struct tlc4541_state *st)
 113 {
 114         int vref;
 115
 116         vref = regulator_get_voltage(st->reg);
 117         if (vref < 0)
 118                 return vref;
 119
 120         vref /= 1000;
 121
 122         return vref;
 123 }
 124
 125 static int tlc4541_read_raw(struct iio_dev *indio_dev,
 126                             struct iio_chan_spec const *chan,
 127                             int *val,
 128                             int *val2,
 129                             long m)
 130 {
 131         int ret = 0;
 132         struct tlc4541_state *st = iio_priv(indio_dev);
 133
 134         switch (m) {
 135         case IIO_CHAN_INFO_RAW:
 136                 ret = iio_device_claim_direct_mode(indio_dev);
 137                 if (ret)
 138                         return ret;
 139                 ret = spi_sync(st->spi, &st->scan_single_msg);
 140                 iio_device_release_direct_mode(indio_dev);
 141                 if (ret < 0)
 142                         return ret;
 143                 *val = be16_to_cpu(st->rx_buf[0]);
 144                 *val = *val >> chan->scan_type.shift;
 145                 *val &= GENMASK(chan->scan_type.realbits - 1, 0);
 146                 return IIO_VAL_INT;
 147         case IIO_CHAN_INFO_SCALE:
 148                 ret = tlc4541_get_range(st);
 149                 if (ret < 0)
 150                         return ret;
 151                 *val = ret;
 152                 *val2 = chan->scan_type.realbits;
 153                 return IIO_VAL_FRACTIONAL_LOG2;
 154         }
 155         return -EINVAL;
 156 }
 157
 158 static const struct iio_info tlc4541_info = {
 159         .read_raw = &tlc4541_read_raw,
 160 };
 161
 162 static int tlc4541_probe(struct spi_device *spi)
 163 {
 164         struct tlc4541_state *st;
 165         struct iio_dev *indio_dev;
 166         const struct tlc4541_chip_info *info;
 167         int ret;
 168         int8_t device_init = 0;
 169
 170         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 171         if (indio_dev == NULL)
 172                 return -ENOMEM;
 173
 174         st = iio_priv(indio_dev);
 175
 176         spi_set_drvdata(spi, indio_dev);
 177
 178         st->spi = spi;
 179
 180         info = &tlc4541_chip_info[spi_get_device_id(spi)->driver_data];
 181
 182         indio_dev->name = spi_get_device_id(spi)->name;
 183         indio_dev->dev.parent = &spi->dev;
 184         indio_dev->modes = INDIO_DIRECT_MODE;
 185         indio_dev->channels = info->channels;
 186         indio_dev->num_channels = info->num_channels;
 187         indio_dev->info = &tlc4541_info;
 188
 189         /* perform reset */
 190         spi_write(spi, &device_init, 1);
 191
 192         /* Setup default message */
 193         st->scan_single_xfer[0].rx_buf = &st->rx_buf[0];
 194         st->scan_single_xfer[0].len = 3;
 195         st->scan_single_xfer[1].delay_usecs = 3;
 196         st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
 197         st->scan_single_xfer[2].len = 2;
 198
 199         spi_message_init_with_transfers(&st->scan_single_msg,
 200                                         st->scan_single_xfer, 3);
 201
 202         st->reg = devm_regulator_get(&spi->dev, "vref");
 203         if (IS_ERR(st->reg))
 204                 return PTR_ERR(st->reg);
 205
 206         ret = regulator_enable(st->reg);
 207         if (ret)
 208                 return ret;
 209
 210         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 211                         &tlc4541_trigger_handler, NULL);
 212         if (ret)
 213                 goto error_disable_reg;
 214
 215         ret = iio_device_register(indio_dev);
 216         if (ret)
 217                 goto error_cleanup_buffer;
 218
 219         return 0;
 220
 221 error_cleanup_buffer:
 222         iio_triggered_buffer_cleanup(indio_dev);
 223 error_disable_reg:
 224         regulator_disable(st->reg);
 225
 226         return ret;
 227 }
 228
 229 static int tlc4541_remove(struct spi_device *spi)
 230 {
 231         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 232         struct tlc4541_state *st = iio_priv(indio_dev);
 233
 234         iio_device_unregister(indio_dev);
 235         iio_triggered_buffer_cleanup(indio_dev);
 236         regulator_disable(st->reg);
 237
 238         return 0;
 239 }
 240
 241 #ifdef CONFIG_OF
 242 static const struct of_device_id tlc4541_dt_ids[] = {
 243         { .compatible = "ti,tlc3541", },
 244         { .compatible = "ti,tlc4541", },
 245         {}
 246 };
 247 MODULE_DEVICE_TABLE(of, tlc4541_dt_ids);
 248 #endif
 249
 250 static const struct spi_device_id tlc4541_id[] = {
 251         {"tlc3541", TLC3541},
 252         {"tlc4541", TLC4541},
 253         {}
 254 };
 255 MODULE_DEVICE_TABLE(spi, tlc4541_id);
 256
 257 static struct spi_driver tlc4541_driver = {
 258         .driver = {
 259                 .name   = "tlc4541",
 260                 .of_match_table = of_match_ptr(tlc4541_dt_ids),
 261         },
 262         .probe          = tlc4541_probe,
 263         .remove         = tlc4541_remove,
 264         .id_table       = tlc4541_id,
 265 };
 266 module_spi_driver(tlc4541_driver);
 267
 268 MODULE_AUTHOR("Phil Reid <preid@electromag.com.au>");
 269 MODULE_DESCRIPTION("Texas Instruments TLC4541 ADC");
 270 MODULE_LICENSE("GPL v2");