[PATCH v4 1/5] ufs: decode string descriptors as UTF-16 big-endian

UFS string descriptors are UTF-16 big-endian (JESD220), but
ufshcd_read_string_desc() fed the raw bytes to utf16_to_utf8(), which reads
host-endian code units, leaving dev_desc->model blank.

Add an endian parameter to utf16_to_utf8() so the caller can specify the byte
order of the source, and pass UTF16_BIG_ENDIAN from the UFS driver, matching
the kernel's utf16s_to_utf8s(..., UTF16_BIG_ENDIAN). Existing callers keep
their current behaviour via UTF16_HOST_ENDIAN.

Signed-off-by: Jorge Ramirez-Ortiz <[email protected]>
---
 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 6a51f337e47..5cde2ab70be 100644
--- a/drivers/ufs/ufs-uclass.c
+++ b/drivers/ufs/ufs-uclass.c
@@ -1766,11 +1766,12 @@ 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..442cc44d077 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);
+uint8_t *utf16_to_utf8(uint8_t *dest, const uint16_t *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..e5861ba96f8 100644
--- a/lib/charset.c
+++ b/lib/charset.c
@@ -11,6 +11,7 @@
 #include <efi_loader.h>
 #include <errno.h>
 #include <malloc.h>
+#include <asm/byteorder.h>
 
 /**
  * codepage_437 - Unicode to codepage 437 translation table
@@ -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)
+uint8_t *utf16_to_utf8(uint8_t *dest, const uint16_t *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..b0faae2d716 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_HOST_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_HOST_ENDIAN);
 
 		if (sanitize_path(fh->path))
 			goto error;
-- 
2.54.0