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, 76 insertions, 0 deletions

diff --git a/include/net/dscp.h b/include/net/dscp.h
new file mode 100644
index 000000000..ba4054086
--- /dev/null
+++ b/include/net/dscp.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2024 Pengutronix, Oleksij Rempel <kernel@pengutronix.de> */
+
+#ifndef __DSCP_H__
+#define __DSCP_H__
+
+/*
+ * DSCP Pools and Codepoint Space Division:
+ *
+ * The Differentiated Services (Diffserv) architecture defines a method for
+ * classifying and managing network traffic using the DS field in IPv4 and IPv6
+ * packet headers. This field can carry one of 64 distinct DSCP (Differentiated
+ * Services Code Point) values, which are divided into three pools based on
+ * their Least Significant Bits (LSB) patterns and intended usage. Each pool has
+ * a specific registration procedure for assigning DSCP values:
+ *
+ * Pool 1 (Standards Action Pool):
+ * - Codepoint Space: xxxxx0
+ *   This pool includes DSCP values ending in '0' (binary), allocated via
+ *   Standards Action. It is intended for globally recognized traffic classes,
+ *   ensuring interoperability across the internet. This pool encompasses
+ *   well-known DSCP values such as CS0-CS7, AFxx, EF, and VOICE-ADMIT.
+ *
+ * Pool 2 (Experimental/Local Use Pool):
+ * - Codepoint Space: xxxx11
+ *   Reserved for DSCP values ending in '11' (binary), this pool is designated
+ *   for Experimental or Local Use. It allows for private or temporary traffic
+ *   marking schemes not intended for standardized global use, facilitating
+ *   testing and network-specific configurations without impacting
+ *   interoperability.
+ *
+ * Pool 3 (Preferential Standardization Pool):
+ * - Codepoint Space: xxxx01
+ *   Initially reserved for experimental or local use, this pool now serves as
+ *   a secondary standardization resource should Pool 1 become exhausted. DSCP
+ *   values ending in '01' (binary) are assigned via Standards Action, with a
+ *   focus on adopting new, standardized traffic classes as the need arises.
+ *
+ * For pool updates see:
+ * https://www.iana.org/assignments/dscp-registry/dscp-registry.xhtml
+ */
+
+/* Pool 1: Standardized DSCP values as per [RFC8126] */
+#define DSCP_CS0 0		/* 000000, [RFC2474] */
+/* CS0 is some times called default (DF) */
+#define DSCP_DF 0		/* 000000, [RFC2474] */
+#define DSCP_CS1 8		/* 001000, [RFC2474] */
+#define DSCP_CS2 16		/* 010000, [RFC2474] */
+#define DSCP_CS3 24		/* 011000, [RFC2474] */
+#define DSCP_CS4 32		/* 100000, [RFC2474] */
+#define DSCP_CS5 40		/* 101000, [RFC2474] */
+#define DSCP_CS6 48		/* 110000, [RFC2474] */
+#define DSCP_CS7 56		/* 111000, [RFC2474] */
+#define DSCP_AF11 10		/* 001010, [RFC2597] */
+#define DSCP_AF12 12		/* 001100, [RFC2597] */
+#define DSCP_AF13 14		/* 001110, [RFC2597] */
+#define DSCP_AF21 18		/* 010010, [RFC2597] */
+#define DSCP_AF22 20		/* 010100, [RFC2597] */
+#define DSCP_AF23 22		/* 010110, [RFC2597] */
+#define DSCP_AF31 26		/* 011010, [RFC2597] */
+#define DSCP_AF32 28		/* 011100, [RFC2597] */
+#define DSCP_AF33 30		/* 011110, [RFC2597] */
+#define DSCP_AF41 34		/* 100010, [RFC2597] */
+#define DSCP_AF42 36		/* 100100, [RFC2597] */
+#define DSCP_AF43 38		/* 100110, [RFC2597] */
+#define DSCP_EF 46		/* 101110, [RFC3246] */
+#define DSCP_VOICE_ADMIT 44	/* 101100, [RFC5865] */
+
+/* Pool 3: Standardized assignments, previously available for experimental/local
+ * use
+ */
+#define DSCP_LE 1		/* 000001, [RFC8622] */
+
+#define DSCP_MAX 64
+
+#endif /* __DSCP_H__ */