staging: iio: adc: ad7476 new SPI ADC driver
New driver handling:
AD7475, AD7476, AD7477, AD7478, AD7466, AD7467, AD7468, AD7495
SPI micropower and high speed 12-/10-/8-Bit ADCs
staging: iio: adc: ad7476 apply list review feedback by Jonathan Cameron
Changes since last RFC post V1:
Mainly list review feedback by Jonathan Cameron
-Remove scan_attrs from chip info structure.
-Remove name from chip info structure, use new spi_device_id instead.
-Allow transfer buffers to live in their own cache lines, to avoid DMA/cache coherency issues.
-Move scan el code into the ring buffer file.
-Use helper function to alloc the pollfunc.
-Use regulator framework and get vref_mv from the regulator in case not specified by pdata.
-Devices with buit-in reference use vref from the chip info structure
-Don't error on missing platform_data
-Make vref_mv type unsigned short
-Print in_scale "Vref / 2^(bits)" if fractional.
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>
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);
+}