drivers/iio/adc/mcp320x.c

   1 /*
   2  * Copyright (C) 2013 Oskar Andero <oskar.andero@gmail.com>
   3  *
   4  * Driver for Microchip Technology's MCP3204 and MCP3208 ADC chips.
   5  * Datasheet can be found here:
   6  * http://ww1.microchip.com/downloads/en/devicedoc/21298c.pdf
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/err.h>
  14 #include <linux/spi/spi.h>
  15 #include <linux/module.h>
  16 #include <linux/iio/iio.h>
  17 #include <linux/regulator/consumer.h>
  18
  19 #define MCP_SINGLE_ENDED        (1 << 3)
  20 #define MCP_START_BIT           (1 << 4)
  21
  22 enum {
  23         mcp3204,
  24         mcp3208,
  25 };
  26
  27 struct mcp320x {
  28         struct spi_device *spi;
  29         struct spi_message msg;
  30         struct spi_transfer transfer[2];
  31
  32         u8 tx_buf;
  33         u8 rx_buf[2];
  34
  35         struct regulator *reg;
  36         struct mutex lock;
  37 };
  38
  39 static int mcp320x_adc_conversion(struct mcp320x *adc, u8 msg)
  40 {
  41         int ret;
  42
  43         adc->tx_buf = msg;
  44         ret = spi_sync(adc->spi, &adc->msg);
  45         if (ret < 0)
  46                 return ret;
  47
  48         return ((adc->rx_buf[0] & 0x3f) << 6)  |
  49                 (adc->rx_buf[1] >> 2);
  50 }
  51
  52 static int mcp320x_read_raw(struct iio_dev *indio_dev,
  53                             struct iio_chan_spec const *channel, int *val,
  54                             int *val2, long mask)
  55 {
  56         struct mcp320x *adc = iio_priv(indio_dev);
  57         int ret = -EINVAL;
  58
  59         mutex_lock(&adc->lock);
  60
  61         switch (mask) {
  62         case IIO_CHAN_INFO_RAW:
  63                 if (channel->differential)
  64                         ret = mcp320x_adc_conversion(adc,
  65                                 MCP_START_BIT | channel->address);
  66                 else
  67                         ret = mcp320x_adc_conversion(adc,
  68                                 MCP_START_BIT | MCP_SINGLE_ENDED |
  69                                 channel->address);
  70                 if (ret < 0)
  71                         goto out;
  72
  73                 *val = ret;
  74                 ret = IIO_VAL_INT;
  75                 break;
  76
  77         case IIO_CHAN_INFO_SCALE:
  78                 /* Digital output code = (4096 * Vin) / Vref */
  79                 ret = regulator_get_voltage(adc->reg);
  80                 if (ret < 0)
  81                         goto out;
  82
  83                 *val = ret / 1000;
  84                 *val2 = 12;
  85                 ret = IIO_VAL_FRACTIONAL_LOG2;
  86                 break;
  87
  88         default:
  89                 break;
  90         }
  91
  92 out:
  93         mutex_unlock(&adc->lock);
  94
  95         return ret;
  96 }
  97
  98 #define MCP320X_VOLTAGE_CHANNEL(num)                            \
  99         {                                                       \
 100                 .type = IIO_VOLTAGE,                            \
 101                 .indexed = 1,                                   \
 102                 .channel = (num),                               \
 103                 .address = (num),                               \
 104                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),   \
 105                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \
 106         }
 107
 108 #define MCP320X_VOLTAGE_CHANNEL_DIFF(num)                       \
 109         {                                                       \
 110                 .type = IIO_VOLTAGE,                            \
 111                 .indexed = 1,                                   \
 112                 .channel = (num * 2),                           \
 113                 .channel2 = (num * 2 + 1),                      \
 114                 .address = (num * 2),                           \
 115                 .differential = 1,                              \
 116                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),   \
 117                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \
 118         }
 119
 120 static const struct iio_chan_spec mcp3204_channels[] = {
 121         MCP320X_VOLTAGE_CHANNEL(0),
 122         MCP320X_VOLTAGE_CHANNEL(1),
 123         MCP320X_VOLTAGE_CHANNEL(2),
 124         MCP320X_VOLTAGE_CHANNEL(3),
 125         MCP320X_VOLTAGE_CHANNEL_DIFF(0),
 126         MCP320X_VOLTAGE_CHANNEL_DIFF(1),
 127 };
 128
 129 static const struct iio_chan_spec mcp3208_channels[] = {
 130         MCP320X_VOLTAGE_CHANNEL(0),
 131         MCP320X_VOLTAGE_CHANNEL(1),
 132         MCP320X_VOLTAGE_CHANNEL(2),
 133         MCP320X_VOLTAGE_CHANNEL(3),
 134         MCP320X_VOLTAGE_CHANNEL(4),
 135         MCP320X_VOLTAGE_CHANNEL(5),
 136         MCP320X_VOLTAGE_CHANNEL(6),
 137         MCP320X_VOLTAGE_CHANNEL(7),
 138         MCP320X_VOLTAGE_CHANNEL_DIFF(0),
 139         MCP320X_VOLTAGE_CHANNEL_DIFF(1),
 140         MCP320X_VOLTAGE_CHANNEL_DIFF(2),
 141         MCP320X_VOLTAGE_CHANNEL_DIFF(3),
 142 };
 143
 144 static const struct iio_info mcp320x_info = {
 145         .read_raw = mcp320x_read_raw,
 146         .driver_module = THIS_MODULE,
 147 };
 148
 149 struct mcp3208_chip_info {
 150         const struct iio_chan_spec *channels;
 151         unsigned int num_channels;
 152 };
 153
 154 static const struct mcp3208_chip_info mcp3208_chip_infos[] = {
 155         [mcp3204] = {
 156                 .channels = mcp3204_channels,
 157                 .num_channels = ARRAY_SIZE(mcp3204_channels)
 158         },
 159         [mcp3208] = {
 160                 .channels = mcp3208_channels,
 161                 .num_channels = ARRAY_SIZE(mcp3208_channels)
 162         },
 163 };
 164
 165 static int mcp320x_probe(struct spi_device *spi)
 166 {
 167         struct iio_dev *indio_dev;
 168         struct mcp320x *adc;
 169         const struct mcp3208_chip_info *chip_info;
 170         int ret;
 171
 172         indio_dev = iio_device_alloc(sizeof(*adc));
 173         if (!indio_dev)
 174                 return -ENOMEM;
 175
 176         adc = iio_priv(indio_dev);
 177         adc->spi = spi;
 178
 179         indio_dev->dev.parent = &spi->dev;
 180         indio_dev->name = spi_get_device_id(spi)->name;
 181         indio_dev->modes = INDIO_DIRECT_MODE;
 182         indio_dev->info = &mcp320x_info;
 183
 184         chip_info = &mcp3208_chip_infos[spi_get_device_id(spi)->driver_data];
 185         indio_dev->channels = chip_info->channels;
 186         indio_dev->num_channels = chip_info->num_channels;
 187
 188         adc->transfer[0].tx_buf = &adc->tx_buf;
 189         adc->transfer[0].len = sizeof(adc->tx_buf);
 190         adc->transfer[1].rx_buf = adc->rx_buf;
 191         adc->transfer[1].len = sizeof(adc->rx_buf);
 192
 193         spi_message_init_with_transfers(&adc->msg, adc->transfer,
 194                                         ARRAY_SIZE(adc->transfer));
 195
 196         adc->reg = regulator_get(&spi->dev, "vref");
 197         if (IS_ERR(adc->reg)) {
 198                 ret = PTR_ERR(adc->reg);
 199                 goto iio_free;
 200         }
 201
 202         ret = regulator_enable(adc->reg);
 203         if (ret < 0)
 204                 goto reg_free;
 205
 206         mutex_init(&adc->lock);
 207
 208         ret = iio_device_register(indio_dev);
 209         if (ret < 0)
 210                 goto reg_disable;
 211
 212         return 0;
 213
 214 reg_disable:
 215         regulator_disable(adc->reg);
 216 reg_free:
 217         regulator_put(adc->reg);
 218 iio_free:
 219         iio_device_free(indio_dev);
 220
 221         return ret;
 222 }
 223
 224 static int mcp320x_remove(struct spi_device *spi)
 225 {
 226         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 227         struct mcp320x *adc = iio_priv(indio_dev);
 228
 229         iio_device_unregister(indio_dev);
 230         regulator_disable(adc->reg);
 231         regulator_put(adc->reg);
 232         iio_device_free(indio_dev);
 233
 234         return 0;
 235 }
 236
 237 static const struct spi_device_id mcp320x_id[] = {
 238         { "mcp3204", mcp3204 },
 239         { "mcp3208", mcp3208 },
 240         { }
 241 };
 242 MODULE_DEVICE_TABLE(spi, mcp320x_id);
 243
 244 static struct spi_driver mcp320x_driver = {
 245         .driver = {
 246                 .name = "mcp320x",
 247                 .owner = THIS_MODULE,
 248         },
 249         .probe = mcp320x_probe,
 250         .remove = mcp320x_remove,
 251         .id_table = mcp320x_id,
 252 };
 253 module_spi_driver(mcp320x_driver);
 254
 255 MODULE_AUTHOR("Oskar Andero <oskar.andero@gmail.com>");
 256 MODULE_DESCRIPTION("Microchip Technology MCP3204/08");
 257 MODULE_LICENSE("GPL v2");