cfi: Add support for strangely endianness broken SoC implementations

This adds the 'data_swap' parameter to the CFI driver, which enables
swapping of data bytes when writing/programming words to the flash.
Note, that this specifically means that bytes are not swapped when
writing command words to the flash chip.  Unless you are using the SAP
in an LS102x chip to program an attached 16-bit NOR flash, you hopefully
do not need this!

Change-Id: I1e6f7169da36f373c880d1756d9c21c9957acc50
Signed-off-by: Esben Haabendal <esben@haabendal.dk>
Reviewed-on: http://openocd.zylin.com/3109
Tested-by: jenkins
Reviewed-by: Paul Fertser <fercerpav@gmail.com>

doc/openocd.texi

@@ -4819,6 +4819,8 @@ The CFI driver can accept the following optional parameters, in any order:
 like AM29LV010 and similar types.
 @item @var{x16_as_x8} ... when a 16-bit flash is hooked up to an 8-bit bus.
 @item @var{bus_swap} ... when data bytes in a 16-bit flash needs to be swapped.
+@item @var{data_swap} ... when data bytes in a 16-bit flash needs to be
+swapped when writing data values (ie. not CFI commands).
 @end itemize
 
 To configure two adjacent banks of 16 MBytes each, both sixteen bits (two bytes)

src/flash/nor/cfi.c

@@ -834,10 +834,13 @@ FLASH_BANK_COMMAND_HANDLER(cfi_flash_bank_command)
 	cfi_info->x16_as_x8 = 0;
 	cfi_info->jedec_probe = 0;
 	cfi_info->not_cfi = 0;
+	cfi_info->data_swap = 0;
 
 	for (unsigned i = 6; i < CMD_ARGC; i++) {
 		if (strcmp(CMD_ARGV[i], "x16_as_x8") == 0)
 			cfi_info->x16_as_x8 = 1;
+		else if (strcmp(CMD_ARGV[i], "data_swap") == 0)
+			cfi_info->data_swap = 1;
 		else if (strcmp(CMD_ARGV[i], "bus_swap") == 0)
 			bus_swap = 1;
 		else if (strcmp(CMD_ARGV[i], "jedec_probe") == 0)
@@ -2331,6 +2334,8 @@ static int cfi_write(struct flash_bank *bank, const uint8_t *buffer, uint32_t of
 	int blk_count;	/* number of bus_width bytes for block copy */
 	uint8_t current_word[CFI_MAX_BUS_WIDTH * 4];	/* word (bus_width size) currently being
 							 *programmed */
+	uint8_t *swapped_buffer = NULL;
+	const uint8_t *real_buffer = NULL;
 	int i;
 	int retval;
 
@@ -2357,8 +2362,14 @@ static int cfi_write(struct flash_bank *bank, const uint8_t *buffer, uint32_t of
 			return retval;
 
 		/* replace only bytes that must be written */
-		for (i = align; (i < bank->bus_width) && (count > 0); i++, count--)
-			current_word[i] = *buffer++;
+		for (i = align;
+		     (i < bank->bus_width) && (count > 0);
+		     i++, count--)
+			if (cfi_info->data_swap)
+				/* data bytes are swapped (reverse endianness) */
+				current_word[bank->bus_width - i] = *buffer++;
+			else
+				current_word[i] = *buffer++;
 
 		retval = cfi_write_word(bank, current_word, write_p);
 		if (retval != ERROR_OK)
@@ -2366,6 +2377,22 @@ static int cfi_write(struct flash_bank *bank, const uint8_t *buffer, uint32_t of
 		write_p += bank->bus_width;
 	}
 
+	if (cfi_info->data_swap && count) {
+		swapped_buffer = malloc(count & ~(bank->bus_width - 1));
+		switch (bank->bus_width) {
+		case 2:
+			buf_bswap16(swapped_buffer, buffer,
+				    count & ~(bank->bus_width - 1));
+			break;
+		case 4:
+			buf_bswap32(swapped_buffer, buffer,
+				    count & ~(bank->bus_width - 1));
+			break;
+		}
+		real_buffer = buffer;
+		buffer = swapped_buffer;
+	}
+
 	/* handle blocks of bus_size aligned bytes */
 	blk_count = count & ~(bank->bus_width - 1);	/* round down, leave tail bytes */
 	switch (cfi_info->pri_id) {
@@ -2435,6 +2462,11 @@ static int cfi_write(struct flash_bank *bank, const uint8_t *buffer, uint32_t of
 			return retval;
 	}
 
+	if (swapped_buffer) {
+		buffer = real_buffer + (buffer - swapped_buffer);
+		free(swapped_buffer);
+	}
+
 	/* return to read array mode, so we can read from flash again for padding */
 	retval = cfi_reset(bank);
 	if (retval != ERROR_OK)
@@ -2451,7 +2483,11 @@ static int cfi_write(struct flash_bank *bank, const uint8_t *buffer, uint32_t of
 
 		/* replace only bytes that must be written */
 		for (i = 0; (i < bank->bus_width) && (count > 0); i++, count--)
-			current_word[i] = *buffer++;
+			if (cfi_info->data_swap)
+				/* data bytes are swapped (reverse endianness) */
+				current_word[bank->bus_width - i] = *buffer++;
+			else
+				current_word[i] = *buffer++;
 
 		retval = cfi_write_word(bank, current_word, write_p);
 		if (retval != ERROR_OK)

src/flash/nor/cfi.h

@@ -29,6 +29,7 @@ struct cfi_flash_bank {
 	int probed;
 
 	enum target_endianness endianness;
+	int data_swap;
 
 	uint16_t manufacturer;
 	uint16_t device_id;