drivers/iio/common/st_sensors/st_sensors_buffer.c

   1 /*
   2  * STMicroelectronics sensors buffer library driver
   3  *
   4  * Copyright 2012-2013 STMicroelectronics Inc.
   5  *
   6  * Denis Ciocca <denis.ciocca@st.com>
   7  *
   8  * Licensed under the GPL-2.
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/iio/iio.h>
  15 #include <linux/iio/trigger.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/iio/buffer.h>
  18 #include <linux/iio/trigger_consumer.h>
  19 #include <linux/iio/triggered_buffer.h>
  20 #include <linux/irqreturn.h>
  21
  22 #include <linux/iio/common/st_sensors.h>
  23
  24
  25 static int st_sensors_get_buffer_element(struct iio_dev *indio_dev, u8 *buf)
  26 {
  27         int i;
  28         struct st_sensor_data *sdata = iio_priv(indio_dev);
  29         unsigned int num_data_channels = sdata->num_data_channels;
  30
  31         for_each_set_bit(i, indio_dev->active_scan_mask, num_data_channels) {
  32                 const struct iio_chan_spec *channel = &indio_dev->channels[i];
  33                 unsigned int bytes_to_read =
  34                         DIV_ROUND_UP(channel->scan_type.realbits +
  35                                      channel->scan_type.shift, 8);
  36                 unsigned int storage_bytes =
  37                         channel->scan_type.storagebits >> 3;
  38
  39                 buf = PTR_ALIGN(buf, storage_bytes);
  40                 if (sdata->tf->read_multiple_byte(&sdata->tb, sdata->dev,
  41                                                   channel->address,
  42                                                   bytes_to_read, buf,
  43                                                   sdata->multiread_bit) <
  44                     bytes_to_read)
  45                         return -EIO;
  46
  47                 /* Advance the buffer pointer */
  48                 buf += storage_bytes;
  49         }
  50
  51         return 0;
  52 }
  53
  54 irqreturn_t st_sensors_trigger_handler(int irq, void *p)
  55 {
  56         int len;
  57         struct iio_poll_func *pf = p;
  58         struct iio_dev *indio_dev = pf->indio_dev;
  59         struct st_sensor_data *sdata = iio_priv(indio_dev);
  60         s64 timestamp;
  61
  62         /*
  63          * If we do timetamping here, do it before reading the values, because
  64          * once we've read the values, new interrupts can occur (when using
  65          * the hardware trigger) and the hw_timestamp may get updated.
  66          * By storing it in a local variable first, we are safe.
  67          */
  68         if (iio_trigger_using_own(indio_dev))
  69                 timestamp = sdata->hw_timestamp;
  70         else
  71                 timestamp = iio_get_time_ns(indio_dev);
  72
  73         len = st_sensors_get_buffer_element(indio_dev, sdata->buffer_data);
  74         if (len < 0)
  75                 goto st_sensors_get_buffer_element_error;
  76
  77         iio_push_to_buffers_with_timestamp(indio_dev, sdata->buffer_data,
  78                                            timestamp);
  79
  80 st_sensors_get_buffer_element_error:
  81         iio_trigger_notify_done(indio_dev->trig);
  82
  83         return IRQ_HANDLED;
  84 }
  85 EXPORT_SYMBOL(st_sensors_trigger_handler);
  86
  87 MODULE_AUTHOR("Denis Ciocca <denis.ciocca@st.com>");
  88 MODULE_DESCRIPTION("STMicroelectronics ST-sensors buffer");
  89 MODULE_LICENSE("GPL v2");