[PATCH 11/14] IIO: max1363 add software ring buffer support using ring_sw

Signed-off-by: Jonathan Cameron <jic23@xxxxxxxxx>

Changes since V2:
* Moved to new registration methodology.
---
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/max1363.h | 14 +++-
drivers/iio/adc/max1363_ring.c | 235 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 249 insertions(+), 1 deletions(-)
create mode 100644 drivers/iio/adc/max1363_ring.c

diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 2a37fee..0c2b6f3 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -3,5 +3,6 @@
#

max1363-y := max1363_core.o
+max1363-$(CONFIG_IIO_RING_BUFFER) += max1363_ring.o

obj-$(CONFIG_MAX1363) += max1363.o
diff --git a/drivers/iio/adc/max1363.h b/drivers/iio/adc/max1363.h
index a9d5c21..8aca81f 100644
--- a/drivers/iio/adc/max1363.h
+++ b/drivers/iio/adc/max1363.h
@@ -228,6 +228,18 @@ struct max1363_state {
struct iio_trigger *trig;
struct regulator *reg;
};
+#ifdef CONFIG_IIO_RING_BUFFER
+
+ssize_t max1363_scan_from_ring(struct device *dev,
+ struct device_attribute *attr,
+ char *buf);
+int max1363_register_ring_funcs_and_init(struct iio_dev *indio_dev);
+void max1363_ring_cleanup(struct iio_dev *indio_dev);
+
+int max1363_initialize_ring(struct iio_ring_buffer *ring);
+void max1363_uninitialize_ring(struct iio_ring_buffer *ring);
+
+#else /* CONFIG_IIO_RING_BUFFER */

static inline void max1363_uninitialize_ring(struct iio_ring_buffer *ring)
{
@@ -253,5 +265,5 @@ max1363_register_ring_funcs_and_init(struct iio_dev *indio_dev)
};

static inline void max1363_ring_cleanup(struct iio_dev *indio_dev) {};
-
+#endif /* CONFIG_IIO_RING_BUFFER */
#endif /* _MAX1363_H_ */
diff --git a/drivers/iio/adc/max1363_ring.c b/drivers/iio/adc/max1363_ring.c
new file mode 100644
index 0000000..6c66b43
--- /dev/null
+++ b/drivers/iio/adc/max1363_ring.c
@@ -0,0 +1,235 @@
+/*
+ * Copyright (C) 2008 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.
+ *
+ * max1363_ring.c
+ */
+
+#include <linux/interrupt.h>
+#include <linux/gpio.h>
+#include <linux/workqueue.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/sysfs.h>
+#include <linux/list.h>
+#include <linux/i2c.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/ring_generic.h>
+#include <linux/iio/ring_sw.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/sysfs.h>
+
+#include "max1363.h"
+
+ssize_t max1363_scan_from_ring(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct iio_dev *dev_info = dev_get_drvdata(dev);
+ struct max1363_state *info = dev_info->dev_data;
+ int i, ret, len = 0;
+ char *ring_data;
+
+ ring_data = kmalloc(info->current_mode->numvals*2, GFP_KERNEL);
+ if (ring_data == NULL) {
+ ret = -ENOMEM;
+ goto error_ret;
+ }
+ ret = dev_info->ring->access.read_last(dev_info->ring, ring_data);
+ if (ret)
+ goto error_free_ring_data;
+ len += sprintf(buf+len, "ring ");
+ for (i = 0; i < info->current_mode->numvals; i++)
+ len += sprintf(buf + len, "%d ",
+ ((int)(ring_data[i*2 + 0] & 0x0F) << 8)
+ + ((int)(ring_data[i*2 + 1])));
+ len += sprintf(buf + len, "\n");
+ kfree(ring_data);
+
+ return len;
+
+error_free_ring_data:
+ kfree(ring_data);
+error_ret:
+ return ret;
+}
+
+/**
+ * max1363_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 max1363_ring_preenable(struct iio_dev *indio_dev)
+{
+ struct max1363_state *st = indio_dev->dev_data;
+ size_t d_size;
+
+ if (indio_dev->ring->access.set_bpd) {
+ d_size = st->current_mode->numvals*2 + sizeof(s64);
+ if (d_size % 8)
+ d_size += 8 - (d_size % 8);
+ indio_dev->ring->access.set_bpd(indio_dev->ring, d_size);
+ }
+
+ return 0;
+}
+
+/**
+ * max1363_ring_postenable() typical ring post enable
+ *
+ * Only not moved into the core for the hardware ring buffer cases
+ * that are more sophisticated.
+ **/
+static int max1363_ring_postenable(struct iio_dev *indio_dev)
+{
+ if (indio_dev->trig == NULL)
+ return 0;
+ return iio_trigger_attach_poll_func(indio_dev->trig,
+ indio_dev->pollfunc);
+}
+
+/**
+ * max1363_ring_predisable() runs just prior to ring buffer being disabled
+ *
+ * Typical predisable function which ensures that no trigger events can
+ * occur before we disable the ring buffer (and hence would have no idea
+ * what to do with them)
+ **/
+static int max1363_ring_predisable(struct iio_dev *indio_dev)
+{
+ if (indio_dev->trig)
+ return iio_trigger_dettach_poll_func(indio_dev->trig,
+ indio_dev->pollfunc);
+ else
+ return 0;
+}
+
+/**
+ * max1363_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.
+ **/
+void max1363_poll_func_th(struct iio_dev *indio_dev)
+{
+ struct max1363_state *st = indio_dev->dev_data;
+
+ schedule_work(&st->poll_work);
+
+ return;
+}
+/**
+ * max1363_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 max1363_poll_bh_to_ring(struct work_struct *work_s)
+{
+ struct max1363_state *st = container_of(work_s, struct max1363_state,
+ poll_work);
+ struct iio_dev *indio_dev = st->indio_dev;
+ struct iio_sw_ring_buffer *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->current_mode->numvals*2 + 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;
+
+ /* Monitor mode prevents reading. Whilst not currently implemented
+ * might as well have this test in here in the meantime as it does
+ * no harm.
+ */
+ if (st->current_mode->numvals == 0)
+ return;
+
+ rxbuf = kmalloc(d_size, GFP_KERNEL);
+ if (rxbuf == NULL)
+ return;
+
+ b_sent = i2c_master_recv(st->client,
+ rxbuf,
+ st->current_mode->numvals*2);
+ 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(&ring->buf, rxbuf, time_ns);
+done:
+ kfree(rxbuf);
+ atomic_dec(&st->protect_ring);
+}
+
+
+int max1363_register_ring_funcs_and_init(struct iio_dev *indio_dev)
+{
+ struct max1363_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(&st->indio_dev->ring->access);
+ indio_dev->pollfunc = kzalloc(sizeof(*indio_dev->pollfunc), GFP_KERNEL);
+ if (indio_dev->pollfunc == NULL) {
+ ret = -ENOMEM;
+ goto error_deallocate_sw_rb;
+ }
+ /* Configure the polling function called on trigger interrupts */
+ indio_dev->pollfunc->poll_func_main = &max1363_poll_func_th;
+ indio_dev->pollfunc->private_data = indio_dev;
+
+ /* Ring buffer functions - here trigger setup related */
+ indio_dev->ring->postenable = &max1363_ring_postenable;
+ indio_dev->ring->preenable = &max1363_ring_preenable;
+ indio_dev->ring->predisable = &max1363_ring_predisable;
+ INIT_WORK(&st->poll_work, &max1363_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 max1363_ring_cleanup(struct iio_dev *indio_dev)
+{
+ kfree(indio_dev->pollfunc);
+ iio_sw_rb_free(indio_dev->ring);
+}
+
+void max1363_uninitialize_ring(struct iio_ring_buffer *ring)
+{
+ iio_ring_buffer_unregister(ring);
+};
+
+int max1363_initialize_ring(struct iio_ring_buffer *ring)
+{
+ return iio_ring_buffer_register(ring);
+};
--
1.6.2

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