Linux设备驱动之IIO子系统——Triggered buffer …

1 const struct iio_buffer_setup_ops sensor_buffer_setup_ops = {
2   .preenable    = my_sensor_buffer_preenable,
3   .postenable   = my_sensor_buffer_postenable,
4   .postdisable  = my_sensor_buffer_postdisable,
5   .predisable   = my_sensor_buffer_predisable,
6 };

1 irqreturn_t sensor_iio_pollfunc(int irq, void *p)
2 {
3     pf->timestamp = iio_get_time_ns((struct indio_dev *)p);
4     return IRQ_WAKE_THREAD;
5 }

 1 irqreturn_t sensor_trigger_handler(int irq, void *p)
 2 {
 3     u16 buf[8];
 4     int bit, i = 0;
 5     struct iio_poll_func *pf = p;
 6     struct iio_dev *indio_dev = pf->indio_dev;
 7 
 8     /* one can use lock here to protect the buffer */
 9     /* mutex_lock(&my_mutex); */ 
10     /* read data for each active channel */
11     for_each_set_bit(bit, indio_dev->active_scan_mask,
12                      indio_dev->masklength)
13         buf[i++] = sensor_get_data(bit) 
14 
15     /*
16      * If iio_dev.scan_timestamp = true, the capture timestamp
17      * will be pushed and stored too, as the last element in the
18      * sample data buffer before pushing it to the device buffers.
19      */
20     iio_push_to_buffers_with_timestamp(indio_dev, buf, timestamp);
21 
22     /* Please unlock any lock */
23 
24     /* mutex_unlock(&my_mutex); */
25 
26     /* Notify trigger */
27 
28     iio_trigger_notify_done(indio_dev->trig);
29     return IRQ_HANDLED;
30 }

iio_triggered_buffer_setup(indio_dev, sensor_iio_polfunc,
                           sensor_trigger_handler,
                           sensor_buffer_setup_ops);

static int my_read_raw(struct iio_dev *indio_dev,
                     const struct iio_chan_spec *chan,
                     int *val, int *val2, long mask)
{
      [...]
      switch (mask) {
     case IIO_CHAN_INFO_RAW:
            if (iio_buffer_enabled(indio_dev))
                  return -EBUSY;
      [...]       
}

　add_trigger file

$ cat /sys/bus/iio/devices/trigger2/name
 sysfstrig2

remove_trigger file

# set trigger2 as current trigger for device0

# echo sysfstrig2 >    /sys/bus/iio/devices/iio:device0/trigger/current_trigger

# echo "" > iio:device0/trigger/current_trigger

static struct resource iio_irq_trigger_resources[] = {
    [0] = {
        .start = IRQ_NR_FOR_YOUR_IRQ,
        .flags = IORESOURCE_IRQ | IORESOURCE_IRQ_LOWEDGE,
           },
};

static struct platform_device iio_irq_trigger = {
    .name = "iio_interrupt_trigger",
    .num_resources = ARRAY_SIZE(iio_irq_trigger_resources),
    .resource = iio_irq_trigger_resources,
};

platform_device_register(&iio_irq_trigger);

$ cd /sys/bus/iio/devices/trigger0/
 $ cat name

# echo "irqtrig85" > /sys/bus/iio/devices/iio:device0/trigger/current_trigger

  mylabel: my_trigger@0{
           compatible = "iio_interrupt_trigger";
           interrupt-parent = <&gpio4>;
           interrupts = <30 0x0>;
};

# mkdir /config
# mount -t configfs none /config

# create a hrtimer trigger
$ mkdir /config/iio/triggers/hrtimer/my_trigger_name
# remove the trigger
$ rmdir /config/iio/triggers/hrtimer/my_trigger_name

$ cat /sys/bus/iio/devices/iio:device0/scan_elements/in_accel_y_type
     le:s12/16>>4

struct iio_chan_spec {
        [...]
        struct {
            char sign; /* Should be 'u' or 's' as explained above */
            u8 realbits;
            u8 storagebits;
            u8 shift;
            u8 repeat;
            enum iio_endian endianness;
        } scan_type;
        [...]
};

struct struct iio_chan_spec accel_channels[] = {
        {
                .type = IIO_ACCEL,
                .modified = 1,
                .channel2 = IIO_MOD_X,
                /* other stuff here */
                .scan_index = 0,
                .scan_type = {
                        .sign = 's',
                        .realbits = 12,
                        .storagebits = 16,
                       .shift = 4,
                        .endianness = IIO_LE,
                },
        }
      /* similar for Y (with channel2 = IIO_MOD_Y, scan_index = 1)
       * and Z (with channel2 = IIO_MOD_Z, scan_index = 2) axis
       */
}

#define BMA220_DATA_SHIFT 2
#define BMA220_DEVICE_NAME "bma220"
#define BMA220_SCALE_AVAILABLE "0.623 1.248 2.491 4.983"

#define BMA220_ACCEL_CHANNEL(index, reg, axis) {           \
   .type = IIO_ACCEL,                                      \
   .address = reg,                                         \
   .modified = 1,                                          \
   .channel2 = IIO_MOD_##axis,                             \
   .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
   .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
   .scan_index = index,                                    \
   .scan_type = {                                          \
         .sign = 's',                                      \
         .realbits = 6,                                    \
         .storagebits = 8,                                 \
         .shift = BMA220_DATA_SHIFT,                       \
         .endianness = IIO_CPU,                            \
   },                                                      \
}

static const struct iio_chan_spec bma220_channels[] = {
   BMA220_ACCEL_CHANNEL(0, BMA220_REG_ACCEL_X, X),
   BMA220_ACCEL_CHANNEL(1, BMA220_REG_ACCEL_Y, Y),
   BMA220_ACCEL_CHANNEL(2, BMA220_REG_ACCEL_Z, Z),
};

jma@jma:~$ ls -l /sys/bus/iio/devices/iio:device0/
(...)
# without modifier, a channel name would have in_accel_raw (bad)
-rw-r--r-- 1 root root 4096 jul 20 14:13 in_accel_scale
-rw-r--r-- 1 root root 4096 jul 20 14:13 in_accel_x_raw
-rw-r--r-- 1 root root 4096 jul 20 14:13 in_accel_y_raw
-rw-r--r-- 1 root root 4096 jul 20 14:13 in_accel_z_raw
(...)

$ cat /sys/bus/iio/devices/iio:device0/scan_elements/in_accel_x_type
le:s6/8>>2

static irqreturn_t bma220_trigger_handler(int irq, void *p)
{
   int ret;
   struct iio_poll_func *pf = p;
   struct iio_dev *indio_dev = pf->indio_dev;
   struct bma220_data *data = iio_priv(indio_dev);
   struct spi_device *spi = data->spi_device;

   mutex_lock(&data->lock);
   data->tx_buf[0] = BMA220_REG_ACCEL_X | BMA220_READ_MASK;
   ret = spi_write_then_read(spi, data->tx_buf, 1, data->buffer,
                       ARRAY_SIZE(bma220_channels) - 1);
   if (ret < 0)
         goto err;

   iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
                              pf->timestamp);
err:
   mutex_unlock(&data->lock);
   iio_trigger_notify_done(indio_dev->trig);
   return IRQ_HANDLED;
}

static int bma220_read_raw(struct iio_dev *indio_dev,
                  struct iio_chan_spec const *chan,
                  int *val, int *val2, long mask)
{
   int ret;
   u8 range_idx
   struct bma220_data *data = iio_priv(indio_dev);

   switch (mask) {
   case IIO_CHAN_INFO_RAW:
           /* If buffer mode enabled, do not process single-channel read */
           if (iio_buffer_enabled(indio_dev))
                   return -EBUSY;
           /* Else we read the channel */
           ret = bma220_read_reg(data->spi_device, chan->address);
           if (ret < 0)
                   return -EINVAL;
           *val = sign_extend32(ret >> BMA220_DATA_SHIFT, 5);

           return IIO_VAL_INT;
   case IIO_CHAN_INFO_SCALE:
           ret = bma220_read_reg(data->spi_device, BMA220_REG_RANGE);
           if (ret < 0)
                   return ret;
           range_idx = ret & BMA220_RANGE_MASK;

           *val = bma220_scale_table[range_idx][0];
           *val2 = bma220_scale_table[range_idx][1];

           return IIO_VAL_INT_PLUS_MICRO;
   }

   return -EINVAL;

}

static int bma220_write_raw(struct iio_dev *indio_dev,
                   struct iio_chan_spec const *chan,
                   int val, int val2, long mask)
{
   int i;
   int ret;
   int index = -1;
   struct bma220_data *data = iio_priv(indio_dev);

   switch (mask) {
   case IIO_CHAN_INFO_SCALE:
         for (i = 0; i < ARRAY_SIZE(bma220_scale_table); i++)
               if (val == bma220_scale_table[i][0] &&
                   val2 == bma220_scale_table[i][1]) {
                     index = i;
                     break;
               }
         if (index < 0)
               return -EINVAL;

         mutex_lock(&data->lock);
         data->tx_buf[0] = BMA220_REG_RANGE;
         data->tx_buf[1] = index;
         ret = spi_write(data->spi_device, data->tx_buf,
                     sizeof(data->tx_buf));
         if (ret < 0)
               dev_err(&data->spi_device->dev,
                     "failed to set measurement range\n");
         mutex_unlock(&data->lock);

         return 0;
   }

   return -EINVAL;

}

echo <desired-scale> > /sys/bus/iio/devices/iio;devices0/in_accel_scale.

static const struct iio_info bma220_info = {
   .driver_module    = THIS_MODULE,
   .read_raw         = bma220_read_raw,
   .write_raw        = bma220_write_raw, /* Only if your driver need it */
};

/*
 * We provide only two mask possibility, allowing to select none or every
 * channels.
 */
static const unsigned long bma220_accel_scan_masks[] = {
   BIT(AXIS_X) | BIT(AXIS_Y) | BIT(AXIS_Z),
   0
};

static int bma220_probe(struct spi_device *spi)

{
   int ret;
   struct iio_dev *indio_dev;
   struct bma220_data *data;

   indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
   if (!indio_dev) {
         dev_err(&spi->dev, "iio allocation failed!\n");
         return -ENOMEM;
   }

   data = iio_priv(indio_dev);
   data->spi_device = spi;
   spi_set_drvdata(spi, indio_dev);
   mutex_init(&data->lock);

   indio_dev->dev.parent = &spi->dev;
   indio_dev->info = &bma220_info;
   indio_dev->name = BMA220_DEVICE_NAME;
   indio_dev->modes = INDIO_DIRECT_MODE;
   indio_dev->channels = bma220_channels;
   indio_dev->num_channels = ARRAY_SIZE(bma220_channels);
   indio_dev->available_scan_masks = bma220_accel_scan_masks;

   ret = bma220_init(data->spi_device);
   if (ret < 0)
         return ret;

   /* this call will enable trigger buffer support for the device */
   ret = iio_triggered_buffer_setup(indio_dev, iio_pollfunc_store_time,
                            bma220_trigger_handler, NULL);
   if (ret < 0) {
         dev_err(&spi->dev, "iio triggered buffer setup failed\n");
         goto err_suspend;
   }

   ret = iio_device_register(indio_dev);
   if (ret < 0) {
         dev_err(&spi->dev, "iio_device_register failed\n");
         iio_triggered_buffer_cleanup(indio_dev);
         goto err_suspend;
   }

   return 0;

err_suspend:
   return bma220_deinit(spi);

}