firmware: exynos-acpm: fix PMIC returned errno

ACPM PMIC command handlers returned a u8 value when they should
have returned either zero or negative error codes.
Translate the APM PMIC errno to linux errno.

Reported-by: Dan Carpenter <[e-mail]>
Closes: https://lore.kernel.org/linux-input/[e-mail]/
Fixes: a88927b534ba ("firmware: add Exynos ACPM protocol driver")
Cc: [e-mail]
Signed-off-by: Tudor Ambarus <[e-mail]>
Signed-off-by: Krzysztof Kozlowski <[e-mail]>

drivers/firmware/samsung/exynos-acpm-pmic.c

···
  * Copyright 2020 Google LLC.
  * Copyright 2024 Linaro Ltd.
  */
+#include <linux/array_size.h>
 #include <linux/bitfield.h>
+#include <linux/errno.h>
 #include <linux/firmware/samsung/exynos-acpm-protocol.h>
 #include <linux/ktime.h>
 #include <linux/types.h>
···
 	ACPM_PMIC_BULK_READ,
 	ACPM_PMIC_BULK_WRITE,
 };
+
+static const int acpm_pmic_linux_errmap[] = {
+	[0] = 0, /* ACPM_PMIC_SUCCESS */
+	[1] = -EACCES, /* Read register can't be accessed or issues to access it. */
+	[2] = -EACCES, /* Write register can't be accessed or issues to access it. */
+};
+
+static int acpm_pmic_to_linux_err(int err)
+{
+	if (err >= 0 && err < ARRAY_SIZE(acpm_pmic_linux_errmap))
+		return acpm_pmic_linux_errmap[err];
+	return -EIO;
+}
 
 static inline u32 acpm_pmic_set_bulk(u32 data, unsigned int i)
 {
···
 
 	*buf = FIELD_GET(ACPM_PMIC_VALUE, xfer.rxd[1]);
 
-	return FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]);
+	return acpm_pmic_to_linux_err(FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]));
 }
 
 static void acpm_pmic_init_bulk_read_cmd(u32 cmd[4], u8 type, u8 reg, u8 chan,
···
 	if (ret)
 		return ret;
 
-	ret = FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]);
+	ret = acpm_pmic_to_linux_err(FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]));
 	if (ret)
 		return ret;
 
···
 	if (ret)
 		return ret;
 
-	return FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]);
+	return acpm_pmic_to_linux_err(FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]));
 }
 
 static void acpm_pmic_init_bulk_write_cmd(u32 cmd[4], u8 type, u8 reg, u8 chan,
···
 	if (ret)
 		return ret;
 
-	return FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]);
+	return acpm_pmic_to_linux_err(FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]));
 }
 
 static void acpm_pmic_init_update_cmd(u32 cmd[4], u8 type, u8 reg, u8 chan,
···
 	if (ret)
 		return ret;
 
-	return FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]);
+	return acpm_pmic_to_linux_err(FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]));
 }