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, 62 insertions, 0 deletions

diff --git a/include/vdso/math64.h b/include/vdso/math64.h
new file mode 100644
index 000000000..22ae212f8
--- /dev/null
+++ b/include/vdso/math64.h
@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __VDSO_MATH64_H
+#define __VDSO_MATH64_H
+
+static __always_inline u32
+__iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
+{
+	u32 ret = 0;
+
+	while (dividend >= divisor) {
+		/* The following asm() prevents the compiler from
+		   optimising this loop into a modulo operation.  */
+		asm("" : "+rm"(dividend));
+
+		dividend -= divisor;
+		ret++;
+	}
+
+	*remainder = dividend;
+
+	return ret;
+}
+
+#if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
+
+#ifndef mul_u64_u32_add_u64_shr
+static __always_inline u64 mul_u64_u32_add_u64_shr(u64 a, u32 mul, u64 b, unsigned int shift)
+{
+	return (u64)((((unsigned __int128)a * mul) + b) >> shift);
+}
+#endif /* mul_u64_u32_add_u64_shr */
+
+#else
+
+#ifndef mul_u64_u32_add_u64_shr
+#ifndef mul_u32_u32
+static inline u64 mul_u32_u32(u32 a, u32 b)
+{
+	return (u64)a * b;
+}
+#define mul_u32_u32 mul_u32_u32
+#endif
+static __always_inline u64 mul_u64_u32_add_u64_shr(u64 a, u32 mul, u64 b, unsigned int shift)
+{
+	u32 ah = a >> 32, al = a;
+	bool ovf;
+	u64 ret;
+
+	ovf = __builtin_add_overflow(mul_u32_u32(al, mul), b, &ret);
+	ret >>= shift;
+	if (ovf && shift)
+		ret += 1ULL << (64 - shift);
+	if (ah)
+		ret += mul_u32_u32(ah, mul) << (32 - shift);
+
+	return ret;
+}
+#endif /* mul_u64_u32_add_u64_shr */
+
+#endif
+
+#endif /* __VDSO_MATH64_H */