iio: Add new operating mode for non triggered sw buffers

There was a need for non triggered software buffer type.  It can be used when
triggered model does not fit and INDIO_BUFFER_HARDWARE causes confusion because
the data stream can be obtained not directly form hardware backend.
Suggested-by: NJonathan Cameron <jic23@kernel.org>
Signed-off-by: NKarol Wrona <k.wrona@samsung.com>
Reviewed-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

drivers/iio/industrialio-buffer.c

@@ -639,6 +639,8 @@ static int __iio_update_buffers(struct iio_dev *indio_dev,
 		indio_dev->currentmode = INDIO_BUFFER_TRIGGERED;
 	} else if (indio_dev->modes & INDIO_BUFFER_HARDWARE) {
 		indio_dev->currentmode = INDIO_BUFFER_HARDWARE;
+	} else if (indio_dev->modes & INDIO_BUFFER_SOFTWARE) {
+		indio_dev->currentmode = INDIO_BUFFER_SOFTWARE;
 	} else { /* Should never be reached */
 		ret = -EINVAL;
 		goto error_run_postdisable;

include/linux/iio/iio.h

@@ -286,10 +286,11 @@ static inline s64 iio_get_time_ns(void)
 /* Device operating modes */
 #define INDIO_DIRECT_MODE		0x01
 #define INDIO_BUFFER_TRIGGERED		0x02
+#define INDIO_BUFFER_SOFTWARE		0x04
 #define INDIO_BUFFER_HARDWARE		0x08
 
 #define INDIO_ALL_BUFFER_MODES					\
-	(INDIO_BUFFER_TRIGGERED | INDIO_BUFFER_HARDWARE)
+	(INDIO_BUFFER_TRIGGERED | INDIO_BUFFER_HARDWARE | INDIO_BUFFER_SOFTWARE)
 
 #define INDIO_MAX_RAW_ELEMENTS		4
 
@@ -593,7 +594,8 @@ void devm_iio_trigger_free(struct device *dev, struct iio_trigger *iio_trig);
 static inline bool iio_buffer_enabled(struct iio_dev *indio_dev)
 {
 	return indio_dev->currentmode
-		& (INDIO_BUFFER_TRIGGERED | INDIO_BUFFER_HARDWARE);
+		& (INDIO_BUFFER_TRIGGERED | INDIO_BUFFER_HARDWARE |
+		   INDIO_BUFFER_SOFTWARE);
 }
 
 /**