staging:iio:dummy Add buffered reading support (9ad2e2e1) · Commits · git / linux-net

drivers/staging/iio/Kconfig

+5 −0

Original line number	Diff line number	Diff line
		@@ -89,6 +89,11 @@ config IIO_SIMPLE_DUMMY_EVENTS
		help
		Add some dummy events to the simple dummy driver.

		config IIO_SIMPLE_DUMMY_BUFFER
		boolean "Buffered capture support"
		depends on IIO_KFIFO_BUF
		help
		Add buffered data capture to the simple dummy driver.

		endif # IIO_SIMPLE_DUMMY

drivers/staging/iio/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -13,6 +13,7 @@ obj-$(CONFIG_IIO_KFIFO_BUF) += kfifo_buf.o
		obj-$(CONFIG_IIO_SIMPLE_DUMMY) += iio_dummy.o
		iio_dummy-y := iio_simple_dummy.o
		iio_dummy-$(CONFIG_IIO_SIMPLE_DUMMY_EVENTS) += iio_simple_dummy_events.o
		iio_dummy-$(CONFIG_IIO_SIMPLE_DUMMY_BUFFER) += iio_simple_dummy_buffer.o

		obj-$(CONFIG_IIO_DUMMY_EVGEN) += iio_dummy_evgen.o

drivers/staging/iio/iio_simple_dummy.c

+64 −9

Original line number	Diff line number	Diff line
		@@ -21,6 +21,7 @@

		#include "iio.h"
		#include "sysfs.h"
		#include "buffer_generic.h"
		#include "iio_simple_dummy.h"

		/*
		@@ -82,7 +83,14 @@ static struct iio_chan_spec iio_dummy_channels[] = {
		* when converting to standard units (microvolts)
		*/
		(1 << IIO_CHAN_INFO_SCALE_SEPARATE),

		/* The ordering of elements in the buffer via an enum */
		.scan_index = voltage0,
		.scan_type = { /* Description of storage in buffer */
		.sign = 'u', /* unsigned */
		.realbits = 13, /* 13 bits */
		.storagebits = 16, /* 16 bits used for storage */
		.shift = 0, /* zero shift */
		},
		#ifdef CONFIG_IIO_SIMPLE_DUMMY_EVENTS
		/*
		* simple event - triggered when value rises above
		@@ -110,6 +118,13 @@ static struct iio_chan_spec iio_dummy_channels[] = {
		* input channels of type IIO_VOLTAGE.
		*/
		(1 << IIO_CHAN_INFO_SCALE_SHARED),
		.scan_index = diffvoltage1m2,
		.scan_type = { /* Description of storage in buffer */
		.sign = 's', /* signed */
		.realbits = 12, /* 12 bits */
		.storagebits = 16, /* 16 bits used for storage */
		.shift = 0, /* zero shift */
		},
		},
		/* Differential ADC channel in_voltage3-voltage4_raw etc*/
		{
		@@ -120,13 +135,13 @@ static struct iio_chan_spec iio_dummy_channels[] = {
		.channel2 = 4,
		.info_mask =
		(1 << IIO_CHAN_INFO_SCALE_SHARED),
		.scan_index = diffvoltage3m4,
		.scan_type = {
		.sign = 's',
		.realbits = 11,
		.storagebits = 16,
		.shift = 0,
		},
		/* DAC channel out_voltage0_raw */
		{
		.type = IIO_VOLTAGE,
		.output = 1,
		.indexed = 1,
		.channel = 0,
		},
		/*
		* 'modified' (i.e. axis specified) acceleration channel
		@@ -145,6 +160,25 @@ static struct iio_chan_spec iio_dummy_channels[] = {
		* calibration.
		*/
		(1 << IIO_CHAN_INFO_CALIBBIAS_SEPARATE),
		.scan_index = accelx,
		.scan_type = { /* Description of storage in buffer */
		.sign = 's', /* signed */
		.realbits = 16, /* 12 bits */
		.storagebits = 16, /* 16 bits used for storage */
		.shift = 0, /* zero shift */
		},
		},
		/*
		* Convenience macro for timestamps. 4 is the index in
		* the buffer.
		*/
		IIO_CHAN_SOFT_TIMESTAMP(4),
		/* DAC channel out_voltage0_raw */
		{
		.type = IIO_VOLTAGE,
		.output = 1,
		.indexed = 1,
		.channel = 0,
		},
		};

		@@ -391,11 +425,29 @@ static int __devinit iio_dummy_probe(int index)
		ret = iio_simple_dummy_events_register(indio_dev);
		if (ret < 0)
		goto error_free_device;
		ret = iio_device_register(indio_dev);

		/* Configure buffered capture support. */
		ret = iio_simple_dummy_configure_buffer(indio_dev);
		if (ret < 0)
		goto error_unregister_events;

		/*
		* Register the channels with the buffer, but avoid the output
		* channel being registered by reducing the number of channels by 1.
		*/
		ret = iio_buffer_register(indio_dev, iio_dummy_channels, 5);
		if (ret < 0)
		goto error_unconfigure_buffer;

		ret = iio_device_register(indio_dev);
		if (ret < 0)
		goto error_unregister_buffer;

		return 0;
		error_unregister_buffer:
		iio_buffer_unregister(indio_dev);
		error_unconfigure_buffer:
		iio_simple_dummy_unconfigure_buffer(indio_dev);
		error_unregister_events:
		iio_simple_dummy_events_unregister(indio_dev);
		error_free_device:
		@@ -429,6 +481,9 @@ static int iio_dummy_remove(int index)

		/* Device specific code to power down etc */

		/* Buffered capture related cleanup */
		iio_buffer_unregister(indio_dev);
		iio_simple_dummy_unconfigure_buffer(indio_dev);

		ret = iio_simple_dummy_events_unregister(indio_dev);
		if (ret)

drivers/staging/iio/iio_simple_dummy.h

+27 −0

Original line number	Diff line number	Diff line
		@@ -78,4 +78,31 @@ iio_simple_dummy_events_unregister(struct iio_dev *indio_dev)

		#endif /* CONFIG_IIO_SIMPLE_DUMMY_EVENTS*/

		/**
		* enum iio_simple_dummy_scan_elements - scan index enum
		* @voltage0: the single ended voltage channel
		* @diffvoltage1m2: first differential channel
		* @diffvoltage3m4: second differenial channel
		* @accelx: acceleration channel
		*
		* Enum provides convenient numbering for the scan index.
		*/
		enum iio_simple_dummy_scan_elements {
		voltage0,
		diffvoltage1m2,
		diffvoltage3m4,
		accelx,
		};

		#ifdef CONFIG_IIO_SIMPLE_DUMMY_BUFFER
		int iio_simple_dummy_configure_buffer(struct iio_dev *indio_dev);
		void iio_simple_dummy_unconfigure_buffer(struct iio_dev *indio_dev);
		#else
		static inline int iio_simple_dummy_configure_buffer(struct iio_dev *indio_dev)
		{
		return 0;
		};
		static inline
		void iio_simple_dummy_unconfigure_buffer(struct iio_dev *indio_dev)
		{};
		#endif /* CONFIG_IIO_SIMPLE_DUMMY_BUFFER */

drivers/staging/iio/iio_simple_dummy_buffer.c

0 → 100644

+206 −0

Original line number	Diff line number	Diff line
		/**
		* 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/slab.h>
		#include <linux/interrupt.h>
		#include <linux/irq.h>
		#include <linux/bitmap.h>

		#include "iio.h"
		#include "trigger_consumer.h"
		#include "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 occuring,
		* 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;
		struct iio_buffer *buffer = indio_dev->buffer;
		int len = 0;
		/*
		* The datasize is obtained from the buffer. It was stored when
		* the preenable setup function was called.
		*/
		size_t datasize = buffer->access->get_bytes_per_datum(buffer);
		u16 *data = kmalloc(datasize, GFP_KERNEL);
		if (data == NULL)
		return -ENOMEM;

		if (buffer->scan_count) {
		/*
		* 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.
		* sofware 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 fidliest option by far.
		* Here lets pretend we have random access. And the values are
		* in the constant table fakedata.
		*/
		int i, j;
		for (i = 0, j = 0; i < buffer->scan_count; i++) {
		j = find_next_bit(buffer->scan_mask,
		indio_dev->masklength, j + 1);
		/* random access read form the 'device' */
		data[i] = fakedata[j];
		len += 2;
		}
		}
		/* Store a timestampe at an 8 byte boundary */
		if (buffer->scan_timestamp)
		(s64 )(((phys_addr_t)data + len
		+ sizeof(s64) - 1) & ~(sizeof(s64) - 1))
		= iio_get_time_ns();
		buffer->access->store_to(buffer, (u8 *)data, pf->timestamp);

		kfree(data);

		/*
		* 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_sw_buffer_preenable:
		* Generic function for equal sized ring elements + 64 bit timestamp
		* Assumes that any combination of channels can be enabled.
		* Typically replaced to implement restrictions on what combinations
		* can be captured (hardware scan modes).
		*/
		.preenable = &iio_sw_buffer_preenable,
		/*
		* 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(indio_dev);
		if (buffer == NULL) {
		ret = -ENOMEM;
		goto error_ret;
		}

		indio_dev->buffer = buffer;
		/* Tell the core how to access the buffer */
		buffer->access = &kfifo_access_funcs;

		/* Number of bytes per element */
		buffer->bpe = 2;
		/* 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.
		*/
		buffer->setup_ops = &iio_simple_dummy_buffer_setup_ops;
		buffer->owner = THIS_MODULE;

		/*
		* 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 top 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 == 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;
		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);
		}