blob: fd74f9166a5f92284563669426b800f66d2b9bbd [file] [log] [blame]
* Copyright (c) 2011 Jonathan Cameron
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
* Buffer handling elements of industrial I/O reference driver.
* Uses the kfifo buffer.
* To test without hardware use the sysfs trigger.
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/bitmap.h>
#include <linux/iio/iio.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/kfifo_buf.h>
#include "iio_simple_dummy.h"
/* Some fake data */
static const s16 fakedata[] = {
[voltage0] = 7,
[diffvoltage1m2] = -33,
[diffvoltage3m4] = -2,
[accelx] = 344,
* iio_simple_dummy_trigger_h() - the trigger handler function
* @irq: the interrupt number
* @p: private data - always a pointer to the poll func.
* This is the guts of buffered capture. On a trigger event occurring,
* if the pollfunc is attached then this handler is called as a threaded
* interrupt (and hence may sleep). It is responsible for grabbing data
* from the device and pushing it into the associated buffer.
static irqreturn_t iio_simple_dummy_trigger_h(int irq, void *p)
struct iio_poll_func *pf = p;
struct iio_dev *indio_dev = pf->indio_dev;
int len = 0;
u16 *data;
data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
if (data == NULL)
goto done;
if (!bitmap_empty(indio_dev->active_scan_mask, indio_dev->masklength)) {
* Three common options here:
* hardware scans: certain combinations of channels make
* up a fast read. The capture will consist of all of them.
* Hence we just call the grab data function and fill the
* buffer without processing.
* software scans: can be considered to be random access
* so efficient reading is just a case of minimal bus
* transactions.
* software culled hardware scans:
* occasionally a driver may process the nearest hardware
* scan to avoid storing elements that are not desired. This
* is the fiddliest option by far.
* Here let's pretend we have random access. And the values are
* in the constant table fakedata.
int i, j;
for (i = 0, j = 0;
i < bitmap_weight(indio_dev->active_scan_mask,
i++, j++) {
j = find_next_bit(indio_dev->active_scan_mask,
indio_dev->masklength, j);
/* random access read from the 'device' */
data[i] = fakedata[j];
len += 2;
iio_push_to_buffers_with_timestamp(indio_dev, data, iio_get_time_ns());
* Tell the core we are done with this trigger and ready for the
* next one.
static const struct iio_buffer_setup_ops iio_simple_dummy_buffer_setup_ops = {
* iio_triggered_buffer_postenable:
* Generic function that simply attaches the pollfunc to the trigger.
* Replace this to mess with hardware state before we attach the
* trigger.
.postenable = &iio_triggered_buffer_postenable,
* iio_triggered_buffer_predisable:
* Generic function that simple detaches the pollfunc from the trigger.
* Replace this to put hardware state back again after the trigger is
* detached but before userspace knows we have disabled the ring.
.predisable = &iio_triggered_buffer_predisable,
int iio_simple_dummy_configure_buffer(struct iio_dev *indio_dev,
const struct iio_chan_spec *channels, unsigned int num_channels)
int ret;
struct iio_buffer *buffer;
/* Allocate a buffer to use - here a kfifo */
buffer = iio_kfifo_allocate(indio_dev);
if (buffer == NULL) {
ret = -ENOMEM;
goto error_ret;
iio_device_attach_buffer(indio_dev, buffer);
/* Enable timestamps by default */
buffer->scan_timestamp = true;
* Tell the core what device type specific functions should
* be run on either side of buffer capture enable / disable.
indio_dev->setup_ops = &iio_simple_dummy_buffer_setup_ops;
* Configure a polling function.
* When a trigger event with this polling function connected
* occurs, this function is run. Typically this grabs data
* from the device.
* NULL for the bottom half. This is normally implemented only if we
* either want to ping a capture now pin (no sleeping) or grab
* a timestamp as close as possible to a data ready trigger firing.
* IRQF_ONESHOT ensures irqs are masked such that only one instance
* of the handler can run at a time.
* "iio_simple_dummy_consumer%d" formatting string for the irq 'name'
* as seen under /proc/interrupts. Remaining parameters as per printk.
indio_dev->pollfunc = iio_alloc_pollfunc(NULL,
if (indio_dev->pollfunc == NULL) {
ret = -ENOMEM;
goto error_free_buffer;
* Notify the core that this device is capable of buffered capture
* driven by a trigger.
indio_dev->modes |= INDIO_BUFFER_TRIGGERED;
ret = iio_buffer_register(indio_dev, channels, num_channels);
if (ret)
goto error_dealloc_pollfunc;
return 0;
return ret;
* iio_simple_dummy_unconfigure_buffer() - release buffer resources
* @indo_dev: device instance state
void iio_simple_dummy_unconfigure_buffer(struct iio_dev *indio_dev)