1 files changed, 206 insertions, 0 deletions
diff --git a/drivers/staging/iio/iio_simple_dummy_buffer.c b/drivers/staging/iio/iio_simple_dummy_buffer.c
new file mode 100644
index 000000000000..f0b36d25414d
--- /dev/null
+++ b/drivers/staging/iio/iio_simple_dummy_buffer.c
@@ -0,0 +1,206 @@
+/**
+ * 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);
+}