![Jonathan Cameron](/assets/img/avatar_default.png)
Very simple buffered reading. Did not provide a trigger as the sysfs trigger already meets that requirement. Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
207 lines
6 KiB
C
207 lines
6 KiB
C
/**
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* Copyright (c) 2011 Jonathan Cameron
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*
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* Buffer handling elements of industrial I/O reference driver.
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* Uses the kfifo buffer.
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*
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* To test without hardware use the sysfs trigger.
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
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#include <linux/bitmap.h>
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#include "iio.h"
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#include "trigger_consumer.h"
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#include "kfifo_buf.h"
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#include "iio_simple_dummy.h"
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/* Some fake data */
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static const s16 fakedata[] = {
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[voltage0] = 7,
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[diffvoltage1m2] = -33,
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[diffvoltage3m4] = -2,
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[accelx] = 344,
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};
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/**
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* iio_simple_dummy_trigger_h() - the trigger handler function
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* @irq: the interrupt number
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* @p: private data - always a pointer to the poll func.
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*
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* This is the guts of buffered capture. On a trigger event occuring,
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* if the pollfunc is attached then this handler is called as a threaded
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* interrupt (and hence may sleep). It is responsible for grabbing data
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* from the device and pushing it into the associated buffer.
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*/
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static irqreturn_t iio_simple_dummy_trigger_h(int irq, void *p)
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{
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struct iio_poll_func *pf = p;
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struct iio_dev *indio_dev = pf->indio_dev;
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struct iio_buffer *buffer = indio_dev->buffer;
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int len = 0;
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/*
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* The datasize is obtained from the buffer. It was stored when
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* the preenable setup function was called.
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*/
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size_t datasize = buffer->access->get_bytes_per_datum(buffer);
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u16 *data = kmalloc(datasize, GFP_KERNEL);
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if (data == NULL)
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return -ENOMEM;
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if (buffer->scan_count) {
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/*
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* Three common options here:
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* hardware scans: certain combinations of channels make
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* up a fast read. The capture will consist of all of them.
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* Hence we just call the grab data function and fill the
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* buffer without processing.
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* sofware scans: can be considered to be random access
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* so efficient reading is just a case of minimal bus
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* transactions.
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* software culled hardware scans:
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* occasionally a driver may process the nearest hardware
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* scan to avoid storing elements that are not desired. This
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* is the fidliest option by far.
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* Here lets pretend we have random access. And the values are
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* in the constant table fakedata.
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*/
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int i, j;
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for (i = 0, j = 0; i < buffer->scan_count; i++) {
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j = find_next_bit(buffer->scan_mask,
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indio_dev->masklength, j + 1);
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/* random access read form the 'device' */
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data[i] = fakedata[j];
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len += 2;
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}
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}
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/* Store a timestampe at an 8 byte boundary */
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if (buffer->scan_timestamp)
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*(s64 *)(((phys_addr_t)data + len
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+ sizeof(s64) - 1) & ~(sizeof(s64) - 1))
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= iio_get_time_ns();
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buffer->access->store_to(buffer, (u8 *)data, pf->timestamp);
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kfree(data);
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/*
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* Tell the core we are done with this trigger and ready for the
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* next one.
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*/
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iio_trigger_notify_done(indio_dev->trig);
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return IRQ_HANDLED;
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}
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static const struct iio_buffer_setup_ops iio_simple_dummy_buffer_setup_ops = {
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/*
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* iio_sw_buffer_preenable:
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* Generic function for equal sized ring elements + 64 bit timestamp
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* Assumes that any combination of channels can be enabled.
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* Typically replaced to implement restrictions on what combinations
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* can be captured (hardware scan modes).
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*/
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.preenable = &iio_sw_buffer_preenable,
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/*
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* iio_triggered_buffer_postenable:
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* Generic function that simply attaches the pollfunc to the trigger.
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* Replace this to mess with hardware state before we attach the
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* trigger.
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*/
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.postenable = &iio_triggered_buffer_postenable,
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/*
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* iio_triggered_buffer_predisable:
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* Generic function that simple detaches the pollfunc from the trigger.
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* Replace this to put hardware state back again after the trigger is
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* detached but before userspace knows we have disabled the ring.
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*/
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.predisable = &iio_triggered_buffer_predisable,
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};
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int iio_simple_dummy_configure_buffer(struct iio_dev *indio_dev)
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{
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int ret;
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struct iio_buffer *buffer;
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/* Allocate a buffer to use - here a kfifo */
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buffer = iio_kfifo_allocate(indio_dev);
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if (buffer == NULL) {
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ret = -ENOMEM;
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goto error_ret;
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}
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indio_dev->buffer = buffer;
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/* Tell the core how to access the buffer */
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buffer->access = &kfifo_access_funcs;
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/* Number of bytes per element */
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buffer->bpe = 2;
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/* Enable timestamps by default */
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buffer->scan_timestamp = true;
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/*
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* Tell the core what device type specific functions should
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* be run on either side of buffer capture enable / disable.
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*/
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buffer->setup_ops = &iio_simple_dummy_buffer_setup_ops;
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buffer->owner = THIS_MODULE;
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/*
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* Configure a polling function.
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* When a trigger event with this polling function connected
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* occurs, this function is run. Typically this grabs data
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* from the device.
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*
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* NULL for the top half. This is normally implemented only if we
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* either want to ping a capture now pin (no sleeping) or grab
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* a timestamp as close as possible to a data ready trigger firing.
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*
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* IRQF_ONESHOT ensures irqs are masked such that only one instance
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* of the handler can run at a time.
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*
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* "iio_simple_dummy_consumer%d" formatting string for the irq 'name'
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* as seen under /proc/interrupts. Remaining parameters as per printk.
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*/
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indio_dev->pollfunc = iio_alloc_pollfunc(NULL,
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&iio_simple_dummy_trigger_h,
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IRQF_ONESHOT,
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indio_dev,
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"iio_simple_dummy_consumer%d",
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indio_dev->id);
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if (indio_dev->pollfunc == NULL) {
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ret = -ENOMEM;
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goto error_free_buffer;
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}
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/*
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* Notify the core that this device is capable of buffered capture
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* driven by a trigger.
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*/
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indio_dev->modes |= INDIO_BUFFER_TRIGGERED;
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return 0;
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error_free_buffer:
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iio_kfifo_free(indio_dev->buffer);
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error_ret:
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return ret;
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}
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/**
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* iio_simple_dummy_unconfigure_buffer() - release buffer resources
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* @indo_dev: device instance state
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*/
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void iio_simple_dummy_unconfigure_buffer(struct iio_dev *indio_dev)
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{
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iio_dealloc_pollfunc(indio_dev->pollfunc);
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iio_kfifo_free(indio_dev->buffer);
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}
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