[PATCH v5 1/6] ufs: decode string descriptors as UTF-16 big-endian

[Jorge Ramirez-Ortiz <jorge.ramirez@oss.qualcomm.com>]

UFS string descriptors are UTF-16 big-endian (JESD220), but
ufshcd_read_string_desc() decoded them as host-endian and so left
dev_desc->model blank.

Give utf16_to_utf8() the source byte order and decode UFS descriptors as
big-endian, matching the kernel's utf16s_to_utf8s(). The EFI file-path
callers consume little-endian UEFI strings and are marked accordingly.

Fixes: 067c1b033282 ("ufs: Call ufs_scsi_bind() from uclass .post_bind")
Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez@oss.qualcomm.com>
---
 drivers/ufs/ufs-uclass.c  |  7 ++++---
 include/charset.h         | 17 ++++++++++++++++-
 lib/charset.c             | 15 ++++++++++++++-
 lib/efi_loader/efi_file.c |  4 ++--
 4 files changed, 36 insertions(+), 7 deletions(-)

diff --git a/drivers/ufs/ufs-uclass.c b/drivers/ufs/ufs-uclass.c
index 6ef01f8e4aa..21aed9f97bd 100644
--- a/drivers/ufs/ufs-uclass.c
+++ b/drivers/ufs/ufs-uclass.c
@@ -1767,11 +1767,12 @@ static int ufshcd_read_string_desc(struct ufs_hba *hba, int desc_index,
 		}
 
 		/*
-		 * the descriptor contains string in UTF16 format
-		 * we need to convert to utf-8 so it can be displayed
+		 * the descriptor contains a big-endian UTF-16 string, convert
+		 * it to utf-8 so it can be displayed
 		 */
 		utf16_to_utf8(buff_ascii,
-			      (uint16_t *)&buf[QUERY_DESC_HDR_SIZE], ascii_len);
+			      (uint16_t *)&buf[QUERY_DESC_HDR_SIZE], ascii_len,
+			      UTF16_BIG_ENDIAN);
 
 		/* replace non-printable or non-ASCII characters with spaces */
 		for (i = 0; i < ascii_len; i++)
diff --git a/include/charset.h b/include/charset.h
index 348bad5883a..79d0ae1ef49 100644
--- a/include/charset.h
+++ b/include/charset.h
@@ -13,6 +13,19 @@
 
 #define MAX_UTF8_PER_UTF16 3
 
+/**
+ * enum utf16_endian - byte order of a UTF-16 string
+ *
+ * @UTF16_HOST_ENDIAN:	code units are in host byte order
+ * @UTF16_LITTLE_ENDIAN:	code units are little-endian
+ * @UTF16_BIG_ENDIAN:	code units are big-endian
+ */
+enum utf16_endian {
+	UTF16_HOST_ENDIAN,
+	UTF16_LITTLE_ENDIAN,
+	UTF16_BIG_ENDIAN,
+};
+
 /*
  * codepage_437 - Unicode to codepage 437 translation table
  */
@@ -299,9 +312,11 @@ size_t u16_strlcat(u16 *dest, const u16 *src, size_t count);
  * @dest:	the destination buffer to write the utf8 characters
  * @src:	the source utf16 string
  * @size:	the number of utf16 characters to convert
+ * @endian:	byte order of the code units in 'src'
  * Return:	the pointer to the first unwritten byte in 'dest'
  */
-uint8_t *utf16_to_utf8(uint8_t *dest, const uint16_t *src, size_t size);
+u8 *utf16_to_utf8(u8 *dest, const u16 *src, size_t size,
+		  enum utf16_endian endian);
 
 /**
  * utf_to_cp() - translate Unicode code point to 8bit codepage
diff --git a/lib/charset.c b/lib/charset.c
index 182c92a50c4..8ccac4048c0 100644
--- a/lib/charset.c
+++ b/lib/charset.c
@@ -5,6 +5,7 @@
  *  Copyright (c) 2017 Rob Clark
  */
 
+#include <asm/byteorder.h>
 #include <charset.h>
 #include <capitalization.h>
 #include <cp437.h>
@@ -458,13 +459,25 @@ size_t u16_strlcat(u16 *dest, const u16 *src, size_t count)
 }
 
 /* Convert UTF-16 to UTF-8.  */
-uint8_t *utf16_to_utf8(uint8_t *dest, const uint16_t *src, size_t size)
+u8 *utf16_to_utf8(u8 *dest, const u16 *src, size_t size,
+		  enum utf16_endian endian)
 {
 	uint32_t code_high = 0;
 
 	while (size--) {
 		uint32_t code = *src++;
 
+		switch (endian) {
+		case UTF16_LITTLE_ENDIAN:
+			code = le16_to_cpu(code);
+			break;
+		case UTF16_BIG_ENDIAN:
+			code = be16_to_cpu(code);
+			break;
+		case UTF16_HOST_ENDIAN:
+			break;
+		}
+
 		if (code_high) {
 			if (code >= 0xDC00 && code <= 0xDFFF) {
 				/* Surrogate pair.  */
diff --git a/lib/efi_loader/efi_file.c b/lib/efi_loader/efi_file.c
index 19b43c4a625..7dee57d594a 100644
--- a/lib/efi_loader/efi_file.c
+++ b/lib/efi_loader/efi_file.c
@@ -184,7 +184,7 @@ static struct efi_file_handle *file_open(struct file_system *fs,
 	int flen = 0;
 
 	if (file_name) {
-		utf16_to_utf8((u8 *)f0, file_name, 1);
+		utf16_to_utf8((u8 *)f0, file_name, 1, UTF16_LITTLE_ENDIAN);
 		flen = u16_strlen(file_name);
 	}
 
@@ -216,7 +216,7 @@ static struct efi_file_handle *file_open(struct file_system *fs,
 			*p++ = '/';
 		}
 
-		utf16_to_utf8((u8 *)p, file_name, flen);
+		utf16_to_utf8((u8 *)p, file_name, flen, UTF16_LITTLE_ENDIAN);
 
 		if (sanitize_path(fh->path))
 			goto error;

base-commit: b8e0086b585791a771416ce51b58ce0097bc0b28
-- 
2.54.0