1 files changed, 207 insertions, 0 deletions
diff --git a/drivers/staging/iio/adc/ad7476_ring.c b/drivers/staging/iio/adc/ad7476_ring.c
new file mode 100644
index 0000000..85de142
--- /dev/null
+++ b/drivers/staging/iio/adc/ad7476_ring.c
@@ -0,0 +1,207 @@
+/*
+ * Copyright 2010 Analog Devices Inc.
+ * Copyright (C) 2008 Jonathan Cameron
+ *
+ * Licensed under the GPL-2 or later.
+ *
+ * ad7476_ring.c
+ */
+
+#include <linux/interrupt.h>
+#include <linux/gpio.h>
+#include <linux/workqueue.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/list.h>
+#include <linux/spi/spi.h>
+
+#include "../iio.h"
+#include "../ring_generic.h"
+#include "../ring_sw.h"
+#include "../trigger.h"
+#include "../sysfs.h"
+
+#include "ad7476.h"
+
+static IIO_SCAN_EL_C(in0, 0, 0, NULL);
+
+static ssize_t ad7476_show_type(struct device *dev,
+				struct device_attribute *attr,
+				char *buf)
+{
+	struct iio_ring_buffer *ring = dev_get_drvdata(dev);
+	struct iio_dev *indio_dev = ring->indio_dev;
+	struct ad7476_state *st = indio_dev->dev_data;
+
+	return sprintf(buf, "%c%d/%d>>%d\n", st->chip_info->sign,
+		       st->chip_info->bits, st->chip_info->storagebits,
+		       st->chip_info->res_shift);
+}
+static IIO_DEVICE_ATTR(in_type, S_IRUGO, ad7476_show_type, NULL, 0);
+
+static struct attribute *ad7476_scan_el_attrs[] = {
+	&iio_scan_el_in0.dev_attr.attr,
+	&iio_const_attr_in0_index.dev_attr.attr,
+	&iio_dev_attr_in_type.dev_attr.attr,
+	NULL,
+};
+
+static struct attribute_group ad7476_scan_el_group = {
+	.name = "scan_elements",
+	.attrs = ad7476_scan_el_attrs,
+};
+
+int ad7476_scan_from_ring(struct ad7476_state *st)
+{
+	struct iio_ring_buffer *ring = st->indio_dev->ring;
+	int ret;
+	u8 *ring_data;
+
+	ring_data = kmalloc(ring->access.get_bytes_per_datum(ring), GFP_KERNEL);
+	if (ring_data == NULL) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+	ret = ring->access.read_last(ring, ring_data);
+	if (ret)
+		goto error_free_ring_data;
+
+	ret = (ring_data[0] << 8) | ring_data[1];
+
+error_free_ring_data:
+	kfree(ring_data);
+error_ret:
+	return ret;
+}
+
+/**
+ * ad7476_ring_preenable() setup the parameters of the ring before enabling
+ *
+ * The complex nature of the setting of the nuber of bytes per datum is due
+ * to this driver currently ensuring that the timestamp is stored at an 8
+ * byte boundary.
+ **/
+static int ad7476_ring_preenable(struct iio_dev *indio_dev)
+{
+	struct ad7476_state *st = indio_dev->dev_data;
+	size_t d_size;
+
+	if (indio_dev->ring->access.set_bytes_per_datum) {
+		d_size = st->chip_info->storagebits / 8 + sizeof(s64);
+		if (d_size % 8)
+			d_size += 8 - (d_size % 8);
+		indio_dev->ring->access.set_bytes_per_datum(indio_dev->ring,
+							    d_size);
+	}
+
+	return 0;
+}
+
+/**
+ * ad7476_poll_func_th() th of trigger launched polling to ring buffer
+ *
+ * As sampling only occurs on i2c comms occuring, leave timestamping until
+ * then.  Some triggers will generate their own time stamp.  Currently
+ * there is no way of notifying them when no one cares.
+ **/
+static void ad7476_poll_func_th(struct iio_dev *indio_dev, s64 time)
+{
+	struct ad7476_state *st = indio_dev->dev_data;
+
+	schedule_work(&st->poll_work);
+	return;
+}
+/**
+ * ad7476_poll_bh_to_ring() bh of trigger launched polling to ring buffer
+ * @work_s:	the work struct through which this was scheduled
+ *
+ * Currently there is no option in this driver to disable the saving of
+ * timestamps within the ring.
+ * I think the one copy of this at a time was to avoid problems if the
+ * trigger was set far too high and the reads then locked up the computer.
+ **/
+static void ad7476_poll_bh_to_ring(struct work_struct *work_s)
+{
+	struct ad7476_state *st = container_of(work_s, struct ad7476_state,
+						  poll_work);
+	struct iio_dev *indio_dev = st->indio_dev;
+	struct iio_sw_ring_buffer *sw_ring = iio_to_sw_ring(indio_dev->ring);
+	s64 time_ns;
+	__u8 *rxbuf;
+	int b_sent;
+	size_t d_size;
+
+	/* Ensure the timestamp is 8 byte aligned */
+	d_size = st->chip_info->storagebits / 8 + sizeof(s64);
+	if (d_size % sizeof(s64))
+		d_size += sizeof(s64) - (d_size % sizeof(s64));
+
+	/* Ensure only one copy of this function running at a time */
+	if (atomic_inc_return(&st->protect_ring) > 1)
+		return;
+
+	rxbuf = kzalloc(d_size,	GFP_KERNEL);
+	if (rxbuf == NULL)
+		return;
+
+	b_sent = spi_read(st->spi, rxbuf, st->chip_info->storagebits / 8);
+	if (b_sent < 0)
+		goto done;
+
+	time_ns = iio_get_time_ns();
+
+	memcpy(rxbuf + d_size - sizeof(s64), &time_ns, sizeof(time_ns));
+
+	indio_dev->ring->access.store_to(&sw_ring->buf, rxbuf, time_ns);
+done:
+	kfree(rxbuf);
+	atomic_dec(&st->protect_ring);
+}
+
+int ad7476_register_ring_funcs_and_init(struct iio_dev *indio_dev)
+{
+	struct ad7476_state *st = indio_dev->dev_data;
+	int ret = 0;
+
+	indio_dev->ring = iio_sw_rb_allocate(indio_dev);
+	if (!indio_dev->ring) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+	/* Effectively select the ring buffer implementation */
+	iio_ring_sw_register_funcs(&indio_dev->ring->access);
+	ret = iio_alloc_pollfunc(indio_dev, NULL, &ad7476_poll_func_th);
+	if (ret)
+		goto error_deallocate_sw_rb;
+
+	/* Ring buffer functions - here trigger setup related */
+
+	indio_dev->ring->preenable = &ad7476_ring_preenable;
+	indio_dev->ring->postenable = &iio_triggered_ring_postenable;
+	indio_dev->ring->predisable = &iio_triggered_ring_predisable;
+	indio_dev->ring->scan_el_attrs = &ad7476_scan_el_group;
+
+	INIT_WORK(&st->poll_work, &ad7476_poll_bh_to_ring);
+
+	/* Flag that polled ring buffering is possible */
+	indio_dev->modes |= INDIO_RING_TRIGGERED;
+	return 0;
+error_deallocate_sw_rb:
+	iio_sw_rb_free(indio_dev->ring);
+error_ret:
+	return ret;
+}
+
+void ad7476_ring_cleanup(struct iio_dev *indio_dev)
+{
+	/* ensure that the trigger has been detached */
+	if (indio_dev->trig) {
+		iio_put_trigger(indio_dev->trig);
+		iio_trigger_dettach_poll_func(indio_dev->trig,
+					      indio_dev->pollfunc);
+	}
+	kfree(indio_dev->pollfunc);
+	iio_sw_rb_free(indio_dev->ring);
+}