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, 59 insertions, 0 deletions

diff --git a/Documentation/block/error-injection.rst b/Documentation/block/error-injection.rst
new file mode 100644
index 000000000..81f31af82
--- /dev/null
+++ b/Documentation/block/error-injection.rst
@@ -0,0 +1,59 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+============================
+Configurable Error Injection
+============================
+
+Overview
+--------
+
+Configurable error injection allows injecting specific block layer status codes
+for sector ranges of a block device.  Errors can be injected unconditionally, or
+with a given probability.
+
+To use configurable error injection, CONFIG_BLK_ERROR_INJECTION must be enabled.
+
+The only interface is the error_injection debugfs file, which is created for
+each registered gendisk.  Writes to this file are used to create or delete rules
+and reads return a list of the current error injection sites.
+
+Options
+-------
+
+The following options specify the operations:
+
+===================	=======================================================
+add			add a new rule
+removeall		remove all existing rules
+===================	=======================================================
+
+The following options specify the details of the rule for the add operation:
+
+===================	=======================================================
+op=<string>		block layer operation this rule applies to.  This uses
+			the XYZ for each REQ_OP_XYZ operation, e.g. READ, WRITE
+			or DISCARD. Mandatory.
+status=<string>		Status to return.  This uses XYZ for each BLK_STS_XYZ
+			code, e.g. IOERR or MEDIUM. Mandatory.
+start=<number>		First block layer sector the rule applies to.
+			Optional, defaults to 0.
+nr_sectors=<number>	Number of sectors this rule applies.
+			Optional, defaults to the remainder of the device.
+chance=<number>		Only return a failure with a likelihood of 1/chance.
+			Optional, defaults to 1 (always).
+===================	=======================================================
+
+Example
+-------
+
+Return BLK_STS_IOERR for one in 10 reads of sector 0 of /dev/nvme0n1:
+
+	$ echo 'add,op=READ,start=0,status=IOERR,chance=10' > /sys/kernel/debug/block/nvme0n1/error_injection
+
+Return BLK_STS_MEDIUM for every write to /dev/nvme0n1:
+
+	$ echo 'add,op=WRITE,start=0,status=MEDIUM' > /sys/kernel/debug/block/nvme0n1/error_injection
+
+Remove all rules for /dev/nvme0n1:
+
+	$ echo 'removeall' > /sys/kernel/debug/block/nvme0n1/error_injection