[PATCH 06/13] iio: buffer: add hardware triggered buffer support

[David Lechner <dlechner@xxxxxxxxxxxx>]

This adds a new mode INDIO_HW_BUFFER_TRIGGERED to the IIO subsystem.

This mode is essentially the hardware version of INDIO_BUFFER_TRIGGERED
where the trigger has the semantics of INDIO_HARDWARE_TRIGGERED and the
buffer has the semantics of INDIO_BUFFER_HARDWARE.

So basically INDIO_HW_BUFFER_TRIGGERED is the same as
INDIO_BUFFER_HARDWARE except that it also enables the trigger when the
buffer is enabled.

Signed-off-by: David Lechner <dlechner@xxxxxxxxxxxx>
---
 drivers/iio/industrialio-buffer.c | 43 ++++++++++++++++++++++++++++++++++++---
 include/linux/iio/iio.h           | 16 ++++++++++++---
 2 files changed, 53 insertions(+), 6 deletions(-)

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 176d31d9f9d8..ffee3043c65a 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -27,6 +27,7 @@
 #include <linux/iio/sysfs.h>
 #include <linux/iio/buffer.h>
 #include <linux/iio/buffer_impl.h>
+#include <linux/iio/trigger.h>
 
 static const char * const iio_endian_prefix[] = {
 	[IIO_BE] = "be",
@@ -867,8 +868,17 @@ static int iio_verify_update(struct iio_dev *indio_dev,
 					insert_buffer->watermark);
 	}
 
-	/* Definitely possible for devices to support both of these. */
-	if ((modes & INDIO_BUFFER_TRIGGERED) && indio_dev->trig) {
+	/* Definitely possible for devices to support all of these. */
+	if (modes & INDIO_HW_BUFFER_TRIGGERED) {
+		/*
+		 * Keep things simple for now and only allow a single buffer to
+		 * be connected in hardware mode.
+		 */
+		if (insert_buffer && !list_empty(&iio_dev_opaque->buffer_list))
+			return -EINVAL;
+		config->mode = INDIO_HW_BUFFER_TRIGGERED;
+		strict_scanmask = true;
+	} else if ((modes & INDIO_BUFFER_TRIGGERED) && indio_dev->trig) {
 		config->mode = INDIO_BUFFER_TRIGGERED;
 	} else if (modes & INDIO_BUFFER_HARDWARE) {
 		/*
@@ -1107,11 +1117,21 @@ static int iio_enable_buffers(struct iio_dev *indio_dev,
 		}
 	}
 
+	if (iio_dev_opaque->currentmode == INDIO_HW_BUFFER_TRIGGERED) {
+		struct iio_trigger *trig = indio_dev->trig;
+
+		if (trig->ops && trig->ops->set_trigger_state) {
+			ret = trig->ops->set_trigger_state(trig, true);
+			if (ret)
+				goto err_disable_buffers;
+		}
+	}
+
 	if (iio_dev_opaque->currentmode == INDIO_BUFFER_TRIGGERED) {
 		ret = iio_trigger_attach_poll_func(indio_dev->trig,
 						   indio_dev->pollfunc);
 		if (ret)
-			goto err_disable_buffers;
+			goto err_disable_hw_trigger;
 	}
 
 	if (indio_dev->setup_ops->postenable) {
@@ -1130,6 +1150,16 @@ static int iio_enable_buffers(struct iio_dev *indio_dev,
 		iio_trigger_detach_poll_func(indio_dev->trig,
 					     indio_dev->pollfunc);
 	}
+err_disable_hw_trigger:
+	if (iio_dev_opaque->currentmode == INDIO_HW_BUFFER_TRIGGERED) {
+		struct iio_trigger *trig = indio_dev->trig;
+
+		if (trig->ops && trig->ops->set_trigger_state) {
+			ret = trig->ops->set_trigger_state(trig, false);
+			if (ret)
+				return ret;
+		}
+	}
 err_disable_buffers:
 	buffer = list_prepare_entry(tmp, &iio_dev_opaque->buffer_list, buffer_list);
 	list_for_each_entry_continue_reverse(buffer, &iio_dev_opaque->buffer_list,
@@ -1174,6 +1204,13 @@ static int iio_disable_buffers(struct iio_dev *indio_dev)
 					     indio_dev->pollfunc);
 	}
 
+	if (iio_dev_opaque->currentmode == INDIO_HW_BUFFER_TRIGGERED) {
+		struct iio_trigger *trig = indio_dev->trig;
+
+		if (trig->ops && trig->ops->set_trigger_state)
+			trig->ops->set_trigger_state(trig, false);
+	}
+
 	list_for_each_entry(buffer, &iio_dev_opaque->buffer_list, buffer_list) {
 		ret2 = iio_buffer_disable(buffer, indio_dev);
 		if (ret2 && !ret)
diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
index d0ce3b71106a..16f62bd38041 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -366,6 +366,11 @@ s64 iio_get_time_ns(const struct iio_dev *indio_dev);
  * they must be managed by the core, but without the entire interrupts/poll
  * functions burden. Interrupts are irrelevant as the data flow is hardware
  * mediated and distributed.
+ * @INDIO_HW_BUFFER_TRIGGERED: Very unusual mode.
+ * This is similar to INDIO_BUFFER_TRIGGERED but everything is done in hardware
+ * therefore there are no poll functions attached. It also implies the semantics
+ * of both INDIO_HARDWARE_TRIGGERED for the trigger and INDIO_BUFFER_HARDWARE
+ * for the buffer.
  */
 #define INDIO_DIRECT_MODE		0x01
 #define INDIO_BUFFER_TRIGGERED		0x02
@@ -373,14 +378,19 @@ s64 iio_get_time_ns(const struct iio_dev *indio_dev);
 #define INDIO_BUFFER_HARDWARE		0x08
 #define INDIO_EVENT_TRIGGERED		0x10
 #define INDIO_HARDWARE_TRIGGERED	0x20
+#define INDIO_HW_BUFFER_TRIGGERED	0x40
 
-#define INDIO_ALL_BUFFER_MODES					\
-	(INDIO_BUFFER_TRIGGERED | INDIO_BUFFER_HARDWARE | INDIO_BUFFER_SOFTWARE)
+#define INDIO_ALL_BUFFER_MODES		\
+	(INDIO_BUFFER_TRIGGERED		\
+	 | INDIO_BUFFER_HARDWARE	\
+	 | INDIO_BUFFER_SOFTWARE	\
+	 | INDIO_HW_BUFFER_TRIGGERED)
 
 #define INDIO_ALL_TRIGGERED_MODES	\
 	(INDIO_BUFFER_TRIGGERED		\
 	 | INDIO_EVENT_TRIGGERED	\
-	 | INDIO_HARDWARE_TRIGGERED)
+	 | INDIO_HARDWARE_TRIGGERED	\
+	 | INDIO_HW_BUFFER_TRIGGERED)
 
 #define INDIO_MAX_RAW_ELEMENTS		4
 

-- 
2.43.0