diff options
Diffstat (limited to 'drivers/iio/dummy/iio_simple_dummy_buffer.c')
| -rw-r--r-- | drivers/iio/dummy/iio_simple_dummy_buffer.c | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/drivers/iio/dummy/iio_simple_dummy_buffer.c b/drivers/iio/dummy/iio_simple_dummy_buffer.c new file mode 100644 index 000000000000..cf44a6f79431 --- /dev/null +++ b/drivers/iio/dummy/iio_simple_dummy_buffer.c @@ -0,0 +1,192 @@ +/** + * 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[] = { + [DUMMY_INDEX_VOLTAGE_0] = 7, + [DUMMY_INDEX_DIFFVOLTAGE_1M2] = -33, + [DUMMY_INDEX_DIFFVOLTAGE_3M4] = -2, + [DUMMY_INDEX_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) + 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, + indio_dev->masklength); + 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()); + + kfree(data); + +done: + /* + * Tell the core we are done with this trigger and ready for the + * next one. + */ + iio_trigger_notify_done(indio_dev->trig); + + return IRQ_HANDLED; +} + +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) +{ + int ret; + struct iio_buffer *buffer; + + /* Allocate a buffer to use - here a kfifo */ + buffer = iio_kfifo_allocate(); + if (!buffer) { + 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, + &iio_simple_dummy_trigger_h, + IRQF_ONESHOT, + indio_dev, + "iio_simple_dummy_consumer%d", + indio_dev->id); + + if (!indio_dev->pollfunc) { + 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; + + return 0; + +error_free_buffer: + iio_kfifo_free(indio_dev->buffer); +error_ret: + 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) +{ + iio_dealloc_pollfunc(indio_dev->pollfunc); + iio_kfifo_free(indio_dev->buffer); +} |