drivers/staging/iio/adc/ad7780.c

   1 /*
   2  * AD7780/AD7781 SPI ADC driver
   3  *
   4  * Copyright 2011 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2.
   7  */
   8
   9 #include <linux/interrupt.h>
  10 #include <linux/device.h>
  11 #include <linux/kernel.h>
  12 #include <linux/slab.h>
  13 #include <linux/sysfs.h>
  14 #include <linux/spi/spi.h>
  15 #include <linux/regulator/consumer.h>
  16 #include <linux/err.h>
  17 #include <linux/sched.h>
  18 #include <linux/gpio.h>
  19 #include <linux/module.h>
  20
  21 #include "../iio.h"
  22 #include "../sysfs.h"
  23
  24 #include "ad7780.h"
  25
  26 #define AD7780_RDY      (1 << 7)
  27 #define AD7780_FILTER   (1 << 6)
  28 #define AD7780_ERR      (1 << 5)
  29 #define AD7780_ID1      (1 << 4)
  30 #define AD7780_ID0      (1 << 3)
  31 #define AD7780_GAIN     (1 << 2)
  32 #define AD7780_PAT1     (1 << 1)
  33 #define AD7780_PAT0     (1 << 0)
  34
  35 struct ad7780_chip_info {
  36         struct iio_chan_spec            channel;
  37 };
  38
  39 struct ad7780_state {
  40         struct spi_device               *spi;
  41         const struct ad7780_chip_info   *chip_info;
  42         struct regulator                *reg;
  43         struct ad7780_platform_data     *pdata;
  44         wait_queue_head_t               wq_data_avail;
  45         bool                            done;
  46         u16                             int_vref_mv;
  47         struct spi_transfer             xfer;
  48         struct spi_message              msg;
  49         /*
  50          * DMA (thus cache coherency maintenance) requires the
  51          * transfer buffers to live in their own cache lines.
  52          */
  53         unsigned int                    data ____cacheline_aligned;
  54 };
  55
  56 enum ad7780_supported_device_ids {
  57         ID_AD7780,
  58         ID_AD7781,
  59 };
  60
  61 static int ad7780_read(struct ad7780_state *st, int *val)
  62 {
  63         int ret;
  64
  65         spi_bus_lock(st->spi->master);
  66
  67         enable_irq(st->spi->irq);
  68         st->done = false;
  69         gpio_set_value(st->pdata->gpio_pdrst, 1);
  70
  71         ret = wait_event_interruptible(st->wq_data_avail, st->done);
  72         disable_irq_nosync(st->spi->irq);
  73         if (ret)
  74                 goto out;
  75
  76         ret = spi_sync_locked(st->spi, &st->msg);
  77         *val = be32_to_cpu(st->data);
  78 out:
  79         gpio_set_value(st->pdata->gpio_pdrst, 0);
  80         spi_bus_unlock(st->spi->master);
  81
  82         return ret;
  83 }
  84
  85 static int ad7780_read_raw(struct iio_dev *indio_dev,
  86                            struct iio_chan_spec const *chan,
  87                            int *val,
  88                            int *val2,
  89                            long m)
  90 {
  91         struct ad7780_state *st = iio_priv(indio_dev);
  92         struct iio_chan_spec channel = st->chip_info->channel;
  93         int ret, smpl = 0;
  94         unsigned long scale_uv;
  95
  96         switch (m) {
  97         case 0:
  98                 mutex_lock(&indio_dev->mlock);
  99                 ret = ad7780_read(st, &smpl);
 100                 mutex_unlock(&indio_dev->mlock);
 101
 102                 if (ret < 0)
 103                         return ret;
 104
 105                 if ((smpl & AD7780_ERR) ||
 106                         !((smpl & AD7780_PAT0) && !(smpl & AD7780_PAT1)))
 107                         return -EIO;
 108
 109                 *val = (smpl >> channel.scan_type.shift) &
 110                         ((1 << (channel.scan_type.realbits)) - 1);
 111                 *val -= (1 << (channel.scan_type.realbits - 1));
 112
 113                 if (!(smpl & AD7780_GAIN))
 114                         *val *= 128;
 115
 116                 return IIO_VAL_INT;
 117         case (1 << IIO_CHAN_INFO_SCALE_SHARED):
 118                 scale_uv = (st->int_vref_mv * 100000)
 119                         >> (channel.scan_type.realbits - 1);
 120                 *val =  scale_uv / 100000;
 121                 *val2 = (scale_uv % 100000) * 10;
 122                 return IIO_VAL_INT_PLUS_MICRO;
 123         }
 124         return -EINVAL;
 125 }
 126
 127 static const struct ad7780_chip_info ad7780_chip_info_tbl[] = {
 128         [ID_AD7780] = {
 129                 .channel = IIO_CHAN(IIO_IN, 0, 1, 0, NULL, 0, 0,
 130                                     (1 << IIO_CHAN_INFO_SCALE_SHARED),
 131                                     0, 0, IIO_ST('s', 24, 32, 8), 0),
 132         },
 133         [ID_AD7781] = {
 134                 .channel = IIO_CHAN(IIO_IN, 0, 1, 0, NULL, 0, 0,
 135                                     (1 << IIO_CHAN_INFO_SCALE_SHARED),
 136                                     0, 0, IIO_ST('s', 20, 32, 12), 0),
 137         },
 138 };
 139
 140 /**
 141  *  Interrupt handler
 142  */
 143 static irqreturn_t ad7780_interrupt(int irq, void *dev_id)
 144 {
 145         struct ad7780_state *st = dev_id;
 146
 147         st->done = true;
 148         wake_up_interruptible(&st->wq_data_avail);
 149
 150         return IRQ_HANDLED;
 151 };
 152
 153 static const struct iio_info ad7780_info = {
 154         .read_raw = &ad7780_read_raw,
 155         .driver_module = THIS_MODULE,
 156 };
 157
 158 static int __devinit ad7780_probe(struct spi_device *spi)
 159 {
 160         struct ad7780_platform_data *pdata = spi->dev.platform_data;
 161         struct ad7780_state *st;
 162         struct iio_dev *indio_dev;
 163         int ret, voltage_uv = 0;
 164
 165         if (!pdata) {
 166                 dev_dbg(&spi->dev, "no platform data?\n");
 167                 return -ENODEV;
 168         }
 169
 170         indio_dev = iio_allocate_device(sizeof(*st));
 171         if (indio_dev == NULL)
 172                 return -ENOMEM;
 173
 174         st = iio_priv(indio_dev);
 175
 176         st->reg = regulator_get(&spi->dev, "vcc");
 177         if (!IS_ERR(st->reg)) {
 178                 ret = regulator_enable(st->reg);
 179                 if (ret)
 180                         goto error_put_reg;
 181
 182                 voltage_uv = regulator_get_voltage(st->reg);
 183         }
 184
 185         st->chip_info =
 186                 &ad7780_chip_info_tbl[spi_get_device_id(spi)->driver_data];
 187
 188         st->pdata = pdata;
 189
 190         if (pdata && pdata->vref_mv)
 191                 st->int_vref_mv = pdata->vref_mv;
 192         else if (voltage_uv)
 193                 st->int_vref_mv = voltage_uv / 1000;
 194         else
 195                 dev_warn(&spi->dev, "reference voltage unspecified\n");
 196
 197         spi_set_drvdata(spi, indio_dev);
 198         st->spi = spi;
 199
 200         indio_dev->dev.parent = &spi->dev;
 201         indio_dev->name = spi_get_device_id(spi)->name;
 202         indio_dev->modes = INDIO_DIRECT_MODE;
 203         indio_dev->channels = &st->chip_info->channel;
 204         indio_dev->num_channels = 1;
 205         indio_dev->info = &ad7780_info;
 206
 207         init_waitqueue_head(&st->wq_data_avail);
 208
 209         /* Setup default message */
 210
 211         st->xfer.rx_buf = &st->data;
 212         st->xfer.len = st->chip_info->channel.scan_type.storagebits / 8;
 213
 214         spi_message_init(&st->msg);
 215         spi_message_add_tail(&st->xfer, &st->msg);
 216
 217         ret = gpio_request_one(st->pdata->gpio_pdrst, GPIOF_OUT_INIT_LOW,
 218                                "AD7780 /PDRST");
 219         if (ret) {
 220                 dev_err(&spi->dev, "failed to request GPIO PDRST\n");
 221                 goto error_disable_reg;
 222         }
 223
 224         ret = request_irq(spi->irq, ad7780_interrupt,
 225                 IRQF_TRIGGER_FALLING, spi_get_device_id(spi)->name, st);
 226         if (ret)
 227                 goto error_free_gpio;
 228
 229         disable_irq(spi->irq);
 230
 231         ret = iio_device_register(indio_dev);
 232         if (ret)
 233                 goto error_free_irq;
 234
 235         return 0;
 236
 237 error_free_irq:
 238         free_irq(spi->irq, st);
 239 error_free_gpio:
 240         gpio_free(st->pdata->gpio_pdrst);
 241 error_disable_reg:
 242         if (!IS_ERR(st->reg))
 243                 regulator_disable(st->reg);
 244 error_put_reg:
 245         if (!IS_ERR(st->reg))
 246                 regulator_put(st->reg);
 247
 248         iio_free_device(indio_dev);
 249
 250         return ret;
 251 }
 252
 253 static int ad7780_remove(struct spi_device *spi)
 254 {
 255         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 256         struct ad7780_state *st = iio_priv(indio_dev);
 257
 258         free_irq(spi->irq, st);
 259         gpio_free(st->pdata->gpio_pdrst);
 260         if (!IS_ERR(st->reg)) {
 261                 regulator_disable(st->reg);
 262                 regulator_put(st->reg);
 263         }
 264         iio_device_unregister(indio_dev);
 265
 266         return 0;
 267 }
 268
 269 static const struct spi_device_id ad7780_id[] = {
 270         {"ad7780", ID_AD7780},
 271         {"ad7781", ID_AD7781},
 272         {}
 273 };
 274
 275 static struct spi_driver ad7780_driver = {
 276         .driver = {
 277                 .name   = "ad7780",
 278                 .bus    = &spi_bus_type,
 279                 .owner  = THIS_MODULE,
 280         },
 281         .probe          = ad7780_probe,
 282         .remove         = __devexit_p(ad7780_remove),
 283         .id_table       = ad7780_id,
 284 };
 285
 286 static int __init ad7780_init(void)
 287 {
 288         return spi_register_driver(&ad7780_driver);
 289 }
 290 module_init(ad7780_init);
 291
 292 static void __exit ad7780_exit(void)
 293 {
 294         spi_unregister_driver(&ad7780_driver);
 295 }
 296 module_exit(ad7780_exit);
 297
 298 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 299 MODULE_DESCRIPTION("Analog Devices AD7780/1 ADC");
 300 MODULE_LICENSE("GPL v2");