iio: proximity: isl29501: Fix return type of isl29501_register_writegrafted

isl29501_register_write() was returning a u32 instead of an int.
Since the function returns negative error codes (such as -ERANGE or
return values from i2c_smbus_write_byte_data()), returning an unsigned
integer type prevents callers from correctly checking for negative error
conditions.

Fix this by changing the function return type from u32 to int.

This was found through manual code review.

Fixes: 1c28799257bc ("iio: light: isl29501: Add support for the ISL29501 ToF sensor.")
Signed-off-by: Salah Triki <salah.triki@gmail.com>
Reviewed-by: Joshua Crofts <joshua.crofts1@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

1 files changed, 107 insertions, 0 deletions

diff --git a/Documentation/driver-api/fpga/fpga-programming.rst b/Documentation/driver-api/fpga/fpga-programming.rst
new file mode 100644
index 000000000..fb4da4240
--- /dev/null
+++ b/Documentation/driver-api/fpga/fpga-programming.rst
@@ -0,0 +1,107 @@
+In-kernel API for FPGA Programming
+==================================
+
+Overview
+--------
+
+The in-kernel API for FPGA programming is a combination of APIs from
+FPGA manager, bridge, and regions.  The actual function used to
+trigger FPGA programming is fpga_region_program_fpga().
+
+fpga_region_program_fpga() uses functionality supplied by
+the FPGA manager and bridges.  It will:
+
+ * lock the region's mutex
+ * lock the mutex of the region's FPGA manager
+ * build a list of FPGA bridges if a method has been specified to do so
+ * disable the bridges
+ * program the FPGA using info passed in :c:expr:`fpga_region->info`.
+ * re-enable the bridges
+ * release the locks
+
+The struct fpga_image_info specifies what FPGA image to program.  It is
+allocated/freed by fpga_image_info_alloc() and freed with
+fpga_image_info_free()
+
+How to program an FPGA using a region
+-------------------------------------
+
+When the FPGA region driver probed, it was given a pointer to an FPGA manager
+driver so it knows which manager to use.  The region also either has a list of
+bridges to control during programming or it has a pointer to a function that
+will generate that list.  Here's some sample code of what to do next::
+
+	#include <linux/fpga/fpga-mgr.h>
+	#include <linux/fpga/fpga-region.h>
+
+	struct fpga_image_info *info;
+	int ret;
+
+	/*
+	 * First, alloc the struct with information about the FPGA image to
+	 * program.
+	 */
+	info = fpga_image_info_alloc(dev);
+	if (!info)
+		return -ENOMEM;
+
+	/* Set flags as needed, such as: */
+	info->flags = FPGA_MGR_PARTIAL_RECONFIG;
+
+	/*
+	 * Indicate where the FPGA image is. This is pseudo-code; you're
+	 * going to use one of these three.
+	 */
+	if (image is in a scatter gather table) {
+
+		info->sgt = [your scatter gather table]
+
+	} else if (image is in a buffer) {
+
+		info->buf = [your image buffer]
+		info->count = [image buffer size]
+
+	} else if (image is in a firmware file) {
+
+		info->firmware_name = devm_kstrdup(dev, firmware_name,
+						   GFP_KERNEL);
+
+	}
+
+	/* Add info to region and do the programming */
+	region->info = info;
+	ret = fpga_region_program_fpga(region);
+
+	/* Deallocate the image info if you're done with it */
+	region->info = NULL;
+	fpga_image_info_free(info);
+
+	if (ret)
+		return ret;
+
+	/* Now enumerate whatever hardware has appeared in the FPGA. */
+
+API for programming an FPGA
+---------------------------
+
+* fpga_region_program_fpga() -  Program an FPGA
+* fpga_image_info() -  Specifies what FPGA image to program
+* fpga_image_info_alloc() -  Allocate an FPGA image info struct
+* fpga_image_info_free() -  Free an FPGA image info struct
+
+.. kernel-doc:: drivers/fpga/fpga-region.c
+   :functions: fpga_region_program_fpga
+
+FPGA Manager flags
+
+.. kernel-doc:: include/linux/fpga/fpga-mgr.h
+   :doc: FPGA Manager flags
+
+.. kernel-doc:: include/linux/fpga/fpga-mgr.h
+   :functions: fpga_image_info
+
+.. kernel-doc:: drivers/fpga/fpga-mgr.c
+   :functions: fpga_image_info_alloc
+
+.. kernel-doc:: drivers/fpga/fpga-mgr.c
+   :functions: fpga_image_info_free