Merge tag 'iio-for-6.8b' of https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into char-misc-next

Jonathan writes:

IIO: 2nd set of new device support, features and cleanup for 6.8

A late/optimistic second pull request. The bots have been poking them
since Wednesday without any issues. There are a few fixes in the
ad7091r5 driver as part of rework to enable the ad7091r8 parts that
are included at start of that series.

Includes pre-work for major changes to the DMA buffers that should
land in 6.9 and will greatly improve performance and flexibility for
high performance devices by enabling DMABUF based zero copy transfers
when we don't need to bounce the data via user space.

New device support
------------------
adi,ad7091r8
 - Major refactor of existing adi,ad7091r5 driver to separate out useful
   shared library code that can be used by I2C and SPI parts.
 - Use that library from a new driver supporting the AD7091R-2, AD7091R-4
   and AD7091R-8 12-Bit SPI ADCs.
 - Series includes some late breaking fixes for the ad7091r5.

microchip,mcp4821
 - New driver for MCP4801, MCP4802, MCP4811, MCP4812, MCP4821 and MCP4822
   I2C single / dual channel DACs.

Cleanup
-------
buffers:
 - Use IIO_SEPARATE in place of some hard-coded 0 values.
dma-buffers:
 - Simplify things to not use an outgoing queue given it only ever has
   up to two elements and we only need to track which is first.
 - Split the iio_dma_buffer_fileio_free() function up to make it easier
   to read and enable reuse in a series lining up for 6.9
iio.h
 - Drop some stale documentation of struct fields that don't exist.

* tag 'iio-for-6.8b' of https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio:
  iio: linux/iio.h: fix Excess kernel-doc description warning
  MAINTAINERS: Add MAINTAINERS entry for AD7091R
  iio: adc: Add support for AD7091R-8
  dt-bindings: iio: Add AD7091R-8
  iio: adc: Split AD7091R-5 config symbol
  iio: adc: ad7091r: Add chip_info callback to get conversion result channel
  iio: adc: ad7091r: Set device mode through chip_info callback
  iio: adc: ad7091r: Remove unneeded probe parameters
  iio: adc: ad7091r: Move chip init data to container struct
  iio: adc: ad7091r: Move generic AD7091R code to base driver and header file
  iio: adc: ad7091r: Enable internal vref if external vref is not supplied
  iio: adc: ad7091r: Allow users to configure device events
  iio: dac: driver for MCP4821
  dt-bindings: iio: dac: add MCP4821
  iio: buffer-dma: split iio_dma_buffer_fileio_free() function
  iio: buffer-dma: Get rid of outgoing queue
  iio: buffer: Use IIO_SEPARATE instead of a hard-coded 0

2 files changed, 3 insertions, 10 deletions

diff --git a/include/linux/iio/buffer-dma.h b/include/linux/iio/buffer-dma.h
index 6564bdcdac66..18d3702fa95d 100644
--- a/include/linux/iio/buffer-dma.h
+++ b/include/linux/iio/buffer-dma.h
@@ -19,14 +19,12 @@ struct device;
 
 /**
  * enum iio_block_state - State of a struct iio_dma_buffer_block
- * @IIO_BLOCK_STATE_DEQUEUED: Block is not queued
  * @IIO_BLOCK_STATE_QUEUED: Block is on the incoming queue
  * @IIO_BLOCK_STATE_ACTIVE: Block is currently being processed by the DMA
  * @IIO_BLOCK_STATE_DONE: Block is on the outgoing queue
  * @IIO_BLOCK_STATE_DEAD: Block has been marked as to be freed
  */
 enum iio_block_state {
-	IIO_BLOCK_STATE_DEQUEUED,
 	IIO_BLOCK_STATE_QUEUED,
 	IIO_BLOCK_STATE_ACTIVE,
 	IIO_BLOCK_STATE_DONE,
@@ -73,12 +71,15 @@ struct iio_dma_buffer_block {
  * @active_block: Block being used in read()
  * @pos: Read offset in the active block
  * @block_size: Size of each block
+ * @next_dequeue: index of next block that will be dequeued
  */
 struct iio_dma_buffer_queue_fileio {
 	struct iio_dma_buffer_block *blocks[2];
 	struct iio_dma_buffer_block *active_block;
 	size_t pos;
 	size_t block_size;
+
+	unsigned int next_dequeue;
 };
 
 /**
@@ -93,7 +94,6 @@ struct iio_dma_buffer_queue_fileio {
  *   list and typically also a list of active blocks in the part that handles
  *   the DMA controller
  * @incoming: List of buffers on the incoming queue
- * @outgoing: List of buffers on the outgoing queue
  * @active: Whether the buffer is currently active
  * @fileio: FileIO state
  */
@@ -105,7 +105,6 @@ struct iio_dma_buffer_queue {
 	struct mutex lock;
 	spinlock_t list_lock;
 	struct list_head incoming;
-	struct list_head outgoing;
 
 	bool active;
 
diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
index d0ce3b71106a..c5b36d2c1e73 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -434,13 +434,7 @@ struct iio_trigger; /* forward declaration */
  * @update_scan_mode:	function to configure device and scan buffer when
  *			channels have changed
  * @debugfs_reg_access:	function to read or write register value of device
- * @of_xlate:		function pointer to obtain channel specifier index.
- *			When #iio-cells is greater than '0', the driver could
- *			provide a custom of_xlate function that reads the
- *			*args* and returns the appropriate index in registered
- *			IIO channels array.
  * @fwnode_xlate:	fwnode based function pointer to obtain channel specifier index.
- *			Functionally the same as @of_xlate.
  * @hwfifo_set_watermark: function pointer to set the current hardware
  *			fifo watermark level; see hwfifo_* entries in
  *			Documentation/ABI/testing/sysfs-bus-iio for details on