mtd: nand: force NAND_CMD_READID onto 8-bit bus

The NAND command helpers tend to automatically shift the column address
for x16 bus devices, since most commands expect a word address, not a
byte address. The Read ID command, however, expects an 8-bit address
(i.e., 0x00, 0x20, or 0x40 should not be translated to 0x00, 0x10, or
0x20).

This fixes the column address for a few drivers which imitate the
nand_base defaults. Note that I don't touch sh_flctl.c, since it already
handles this problem slightly differently (note its comment "READID is
always performed using an 8-bit bus").

I have not tested this patch, as I only have x8 parts up for testing at
this point. Hopefully that can change soon...
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Tested-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Tested-By: Pekon Gupta <pekon@ti.com>

drivers/mtd/nand/atmel_nand.c

@@ -1659,8 +1659,8 @@ static void nfc_select_chip(struct mtd_info *mtd, int chip)
 		nfc_writel(host->nfc->hsmc_regs, CTRL, NFC_CTRL_ENABLE);
 }
 
-static int nfc_make_addr(struct mtd_info *mtd, int column, int page_addr,
-		unsigned int *addr1234, unsigned int *cycle0)
+static int nfc_make_addr(struct mtd_info *mtd, int command, int column,
+		int page_addr, unsigned int *addr1234, unsigned int *cycle0)
 {
 	struct nand_chip *chip = mtd->priv;
 
@@ -1674,7 +1674,8 @@ static int nfc_make_addr(struct mtd_info *mtd, int column, int page_addr,
 	*addr1234 = 0;
 
 	if (column != -1) {
-		if (chip->options & NAND_BUSWIDTH_16)
+		if (chip->options & NAND_BUSWIDTH_16 &&
+				!nand_opcode_8bits(command))
 			column >>= 1;
 		addr_bytes[acycle++] = column & 0xff;
 		if (mtd->writesize > 512)
@@ -1787,8 +1788,8 @@ static void nfc_nand_command(struct mtd_info *mtd, unsigned int command,
 	}
 
 	if (do_addr)
-		acycle = nfc_make_addr(mtd, column, page_addr, &addr1234,
-				&cycle0);
+		acycle = nfc_make_addr(mtd, command, column, page_addr,
+				&addr1234, &cycle0);
 
 	nfc_addr_cmd = cmd1 | cmd2 | vcmd2 | acycle | csid | dataen | nfcwr;
 	nfc_send_command(host, nfc_addr_cmd, addr1234, cycle0);

drivers/mtd/nand/au1550nd.c

@@ -307,7 +307,8 @@ static void au1550_command(struct mtd_info *mtd, unsigned command, int column, i
 		/* Serially input address */
 		if (column != -1) {
 			/* Adjust columns for 16 bit buswidth */
-			if (this->options & NAND_BUSWIDTH_16)
+			if (this->options & NAND_BUSWIDTH_16 &&
+					!nand_opcode_8bits(command))
 				column >>= 1;
 			ctx->write_byte(mtd, column);
 		}

drivers/mtd/nand/diskonchip.c

@@ -698,7 +698,8 @@ static void doc2001plus_command(struct mtd_info *mtd, unsigned command, int colu
 		/* Serially input address */
 		if (column != -1) {
 			/* Adjust columns for 16 bit buswidth */
-			if (this->options & NAND_BUSWIDTH_16)
+			if (this->options & NAND_BUSWIDTH_16 &&
+					!nand_opcode_8bits(command))
 				column >>= 1;
 			WriteDOC(column, docptr, Mplus_FlashAddress);
 		}

drivers/mtd/nand/nand_base.c

@@ -589,7 +589,8 @@ static void nand_command(struct mtd_info *mtd, unsigned int command,
 	/* Serially input address */
 	if (column != -1) {
 		/* Adjust columns for 16 bit buswidth */
-		if (chip->options & NAND_BUSWIDTH_16)
+		if (chip->options & NAND_BUSWIDTH_16 &&
+				!nand_opcode_8bits(command))
 			column >>= 1;
 		chip->cmd_ctrl(mtd, column, ctrl);
 		ctrl &= ~NAND_CTRL_CHANGE;
@@ -680,7 +681,8 @@ static void nand_command_lp(struct mtd_info *mtd, unsigned int command,
 		/* Serially input address */
 		if (column != -1) {
 			/* Adjust columns for 16 bit buswidth */
-			if (chip->options & NAND_BUSWIDTH_16)
+			if (chip->options & NAND_BUSWIDTH_16 &&
+					!nand_opcode_8bits(command))
 				column >>= 1;
 			chip->cmd_ctrl(mtd, column, ctrl);
 			ctrl &= ~NAND_CTRL_CHANGE;

drivers/mtd/nand/nuc900_nand.c

@@ -151,7 +151,8 @@ static void nuc900_nand_command_lp(struct mtd_info *mtd, unsigned int command,
 	if (column != -1 || page_addr != -1) {
 
 		if (column != -1) {
-			if (chip->options & NAND_BUSWIDTH_16)
+			if (chip->options & NAND_BUSWIDTH_16 &&
+					!nand_opcode_8bits(command))
 				column >>= 1;
 			write_addr_reg(nand, column);
 			write_addr_reg(nand, column >> 8 | ENDADDR);

include/linux/mtd/nand.h

@@ -832,4 +832,14 @@ static inline bool nand_is_slc(struct nand_chip *chip)
 {
 	return chip->bits_per_cell == 1;
 }
+
+/**
+ * Check if the opcode's address should be sent only on the lower 8 bits
+ * @command: opcode to check
+ */
+static inline int nand_opcode_8bits(unsigned int command)
+{
+	return command == NAND_CMD_READID;
+}
+
 #endif /* __LINUX_MTD_NAND_H */