staging: IIO: ADC: New driver for AD7606/AD7606-6/AD7606-4

This patch adds support for the:
AD7606/AD7606-6/AD7606-4 8/6/4-Channel Data Acquisition
system (DAS) with 16-Bit, Bipolar, Simultaneous Sampling ADC.

Changes since V1:
IIO: ADC: New driver for AD7606/AD7606-6/AD7606-4: Apply review feedback

Rename sysfs node oversampling to oversampling_ratio.
Kconfig: Add GPIOLIB dependency.
Use range in mV to better match HWMON.
Rename ad7606_check_oversampling.
Fix various comments and style.
Reorder is_visible cases.
Use new gpio_request_one/array and friends.
Drop check for SPI max_speed_hz.

Changes since V2:
IIO: ADC: New driver for AD7606/AD7606-6/AD7606-4: Apply review feedback

Documentation: specify unit
Avoid raise condition in ad7606_scan_direct()
Check return value of bus ops read_block()

Changes since V3:
IIO: ADC: New driver for AD7606/AD7606-6/AD7606-4: Add missing include file

Add linux/sched.h

Changes since V4:
IIO: ADC: New driver for AD7606/AD7606-6/AD7606-4: Fix kconfig declaration

consistently use tristate to avoid configuration mismatches

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 266 insertions, 0 deletions

diff --git a/drivers/staging/iio/adc/ad7606_ring.c b/drivers/staging/iio/adc/ad7606_ring.c
new file mode 100644
index 000000000000..9889680232d8
--- /dev/null
+++ b/drivers/staging/iio/adc/ad7606_ring.c
@@ -0,0 +1,266 @@
+/*
+ * Copyright 2011 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2.
+ *
+ */
+
+#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 "../iio.h"
+#include "../ring_generic.h"
+#include "../ring_sw.h"
+#include "../trigger.h"
+#include "../sysfs.h"
+
+#include "ad7606.h"
+
+static IIO_SCAN_EL_C(in0, 0, 0, NULL);
+static IIO_SCAN_EL_C(in1, 1, 0, NULL);
+static IIO_SCAN_EL_C(in2, 2, 0, NULL);
+static IIO_SCAN_EL_C(in3, 3, 0, NULL);
+static IIO_SCAN_EL_C(in4, 4, 0, NULL);
+static IIO_SCAN_EL_C(in5, 5, 0, NULL);
+static IIO_SCAN_EL_C(in6, 6, 0, NULL);
+static IIO_SCAN_EL_C(in7, 7, 0, NULL);
+
+static ssize_t ad7606_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 ad7606_state *st = indio_dev->dev_data;
+
+	return sprintf(buf, "%c%d/%d\n", st->chip_info->sign,
+		       st->chip_info->bits, st->chip_info->bits);
+}
+static IIO_DEVICE_ATTR(in_type, S_IRUGO, ad7606_show_type, NULL, 0);
+
+static struct attribute *ad7606_scan_el_attrs[] = {
+	&iio_scan_el_in0.dev_attr.attr,
+	&iio_const_attr_in0_index.dev_attr.attr,
+	&iio_scan_el_in1.dev_attr.attr,
+	&iio_const_attr_in1_index.dev_attr.attr,
+	&iio_scan_el_in2.dev_attr.attr,
+	&iio_const_attr_in2_index.dev_attr.attr,
+	&iio_scan_el_in3.dev_attr.attr,
+	&iio_const_attr_in3_index.dev_attr.attr,
+	&iio_scan_el_in4.dev_attr.attr,
+	&iio_const_attr_in4_index.dev_attr.attr,
+	&iio_scan_el_in5.dev_attr.attr,
+	&iio_const_attr_in5_index.dev_attr.attr,
+	&iio_scan_el_in6.dev_attr.attr,
+	&iio_const_attr_in6_index.dev_attr.attr,
+	&iio_scan_el_in7.dev_attr.attr,
+	&iio_const_attr_in7_index.dev_attr.attr,
+	&iio_dev_attr_in_type.dev_attr.attr,
+	NULL,
+};
+
+static mode_t ad7606_scan_el_attr_is_visible(struct kobject *kobj,
+				     struct attribute *attr, int n)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct iio_ring_buffer *ring = dev_get_drvdata(dev);
+	struct iio_dev *indio_dev = ring->indio_dev;
+	struct ad7606_state *st = indio_dev->dev_data;
+
+	mode_t mode = attr->mode;
+
+	if (st->chip_info->num_channels <= 6 &&
+		(attr == &iio_scan_el_in7.dev_attr.attr ||
+		attr == &iio_const_attr_in7_index.dev_attr.attr ||
+		attr == &iio_scan_el_in6.dev_attr.attr ||
+		attr == &iio_const_attr_in6_index.dev_attr.attr))
+		mode = 0;
+	else if (st->chip_info->num_channels <= 4 &&
+		(attr == &iio_scan_el_in5.dev_attr.attr ||
+		attr == &iio_const_attr_in5_index.dev_attr.attr ||
+		attr == &iio_scan_el_in4.dev_attr.attr ||
+		attr == &iio_const_attr_in4_index.dev_attr.attr))
+		mode = 0;
+
+	return mode;
+}
+
+static struct attribute_group ad7606_scan_el_group = {
+	.name = "scan_elements",
+	.attrs = ad7606_scan_el_attrs,
+	.is_visible = ad7606_scan_el_attr_is_visible,
+};
+
+int ad7606_scan_from_ring(struct ad7606_state *st, unsigned ch)
+{
+	struct iio_ring_buffer *ring = st->indio_dev->ring;
+	int ret;
+	u16 *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, (u8 *) ring_data);
+	if (ret)
+		goto error_free_ring_data;
+
+	ret = ring_data[ch];
+
+error_free_ring_data:
+	kfree(ring_data);
+error_ret:
+	return ret;
+}
+
+/**
+ * ad7606_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 ad7606_ring_preenable(struct iio_dev *indio_dev)
+{
+	struct ad7606_state *st = indio_dev->dev_data;
+	struct iio_ring_buffer *ring = indio_dev->ring;
+	size_t d_size;
+
+	d_size = st->chip_info->num_channels *
+		 st->chip_info->bits / 8 + sizeof(s64);
+
+	if (d_size % sizeof(s64))
+		d_size += sizeof(s64) - (d_size % sizeof(s64));
+
+	if (ring->access.set_bytes_per_datum)
+		ring->access.set_bytes_per_datum(ring, d_size);
+
+	st->d_size = d_size;
+
+	return 0;
+}
+
+/**
+ * ad7606_poll_func_th() th of trigger launched polling to ring buffer
+ *
+ **/
+static void ad7606_poll_func_th(struct iio_dev *indio_dev, s64 time)
+{
+	struct ad7606_state *st = indio_dev->dev_data;
+	gpio_set_value(st->pdata->gpio_convst, 1);
+
+	return;
+}
+/**
+ * ad7606_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 ad7606_poll_bh_to_ring(struct work_struct *work_s)
+{
+	struct ad7606_state *st = container_of(work_s, struct ad7606_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);
+	struct iio_ring_buffer *ring = indio_dev->ring;
+	s64 time_ns;
+	__u8 *buf;
+	int ret;
+
+	/* Ensure only one copy of this function running at a time */
+	if (atomic_inc_return(&st->protect_ring) > 1)
+		return;
+
+	buf = kzalloc(st->d_size, GFP_KERNEL);
+	if (buf == NULL)
+		return;
+
+	if (st->have_frstdata) {
+		ret = st->bops->read_block(st->dev, 1, buf);
+		if (ret)
+			goto done;
+		if (!gpio_get_value(st->pdata->gpio_frstdata)) {
+			/* This should never happen. However
+			 * some signal glitch caused by bad PCB desgin or
+			 * electrostatic discharge, could cause an extra read
+			 * or clock. This allows recovery.
+			 */
+			ad7606_reset(st);
+			goto done;
+		}
+		ret = st->bops->read_block(st->dev,
+			st->chip_info->num_channels - 1, buf + 2);
+		if (ret)
+			goto done;
+	} else {
+		ret = st->bops->read_block(st->dev,
+			st->chip_info->num_channels, buf);
+		if (ret)
+			goto done;
+	}
+
+	time_ns = iio_get_time_ns();
+	memcpy(buf + st->d_size - sizeof(s64), &time_ns, sizeof(time_ns));
+
+	ring->access.store_to(&sw_ring->buf, buf, time_ns);
+done:
+	gpio_set_value(st->pdata->gpio_convst, 0);
+	kfree(buf);
+	atomic_dec(&st->protect_ring);
+}
+
+int ad7606_register_ring_funcs_and_init(struct iio_dev *indio_dev)
+{
+	struct ad7606_state *st = indio_dev->dev_data;
+	int ret;
+
+	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, &ad7606_poll_func_th);
+	if (ret)
+		goto error_deallocate_sw_rb;
+
+	/* Ring buffer functions - here trigger setup related */
+
+	indio_dev->ring->preenable = &ad7606_ring_preenable;
+	indio_dev->ring->postenable = &iio_triggered_ring_postenable;
+	indio_dev->ring->predisable = &iio_triggered_ring_predisable;
+	indio_dev->ring->scan_el_attrs = &ad7606_scan_el_group;
+
+	INIT_WORK(&st->poll_work, &ad7606_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 ad7606_ring_cleanup(struct iio_dev *indio_dev)
+{
+	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);
+}