[U-Boot] [RFC PATCH v2] sf: support chips using 4-byte addressing

[Chris Packham <judge.packham@gmail.com>]

SPI chips with >16MB capacity use 4-byte addressing to allow
accessing beyond 16MB. When the size of the SPI flash exceeds 16MB
switch to using 4 byte addressing.

Signed-off-by: Chris Packham <judge.packham@gmail.com>

---

Changes in v2:
- automatically detect when 4 byte addressing is needed. This is similar
  to how the linux kernel does the same detection

 drivers/mtd/spi/sf_internal.h |  4 ++--
 drivers/mtd/spi/spi_flash.c   | 32 ++++++++++++++++++++++----------
 include/spi_flash.h           |  2 ++
 3 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/drivers/mtd/spi/sf_internal.h b/drivers/mtd/spi/sf_internal.h
index cde4cfbf2e32..db4532849145 100644
--- a/drivers/mtd/spi/sf_internal.h
+++ b/drivers/mtd/spi/sf_internal.h
@@ -25,8 +25,8 @@ enum spi_nor_option_flags {
 	SNOR_F_USE_FSR		= BIT(1),
 };
 
-#define SPI_FLASH_3B_ADDR_LEN		3
-#define SPI_FLASH_CMD_LEN		(1 + SPI_FLASH_3B_ADDR_LEN)
+#define SPI_FLASE_MAX_ADDR_WIDTH	4
+#define SPI_FLASH_CMD_LEN		(1 + SPI_FLASE_MAX_ADDR_WIDTH)
 #define SPI_FLASH_16MB_BOUN		0x1000000
 
 /* CFI Manufacture ID's */
diff --git a/drivers/mtd/spi/spi_flash.c b/drivers/mtd/spi/spi_flash.c
index 7f6e9ae23ea8..a3efaa129231 100644
--- a/drivers/mtd/spi/spi_flash.c
+++ b/drivers/mtd/spi/spi_flash.c
@@ -22,12 +22,19 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
-static void spi_flash_addr(u32 addr, u8 *cmd)
+static void spi_flash_addr(u32 addr, u8 *cmd, u8 addr_width)
 {
 	/* cmd[0] is actual command */
-	cmd[1] = addr >> 16;
-	cmd[2] = addr >> 8;
-	cmd[3] = addr >> 0;
+	if (addr_width == 4) {
+		cmd[1] = addr >> 24;
+		cmd[2] = addr >> 16;
+		cmd[3] = addr >> 8;
+		cmd[4] = addr;
+	} else {
+		cmd[1] = addr >> 16;
+		cmd[2] = addr >> 8;
+		cmd[3] = addr >> 0;
+	}
 }
 
 static int read_sr(struct spi_flash *flash, u8 *rs)
@@ -357,12 +364,13 @@ int spi_flash_cmd_erase_ops(struct spi_flash *flash, u32 offset, size_t len)
 		if (ret < 0)
 			return ret;
 #endif
-		spi_flash_addr(erase_addr, cmd);
+		spi_flash_addr(erase_addr, cmd, flash->addr_width);
 
 		debug("SF: erase %2x %2x %2x %2x (%x)\n", cmd[0], cmd[1],
 		      cmd[2], cmd[3], erase_addr);
 
-		ret = spi_flash_write_common(flash, cmd, sizeof(cmd), NULL, 0);
+		ret = spi_flash_write_common(flash, cmd, flash->addr_width + 1,
+					     NULL, 0);
 		if (ret < 0) {
 			debug("SF: erase failed\n");
 			break;
@@ -415,12 +423,12 @@ int spi_flash_cmd_write_ops(struct spi_flash *flash, u32 offset,
 			chunk_len = min(chunk_len,
 					(size_t)spi->max_write_size);
 
-		spi_flash_addr(write_addr, cmd);
+		spi_flash_addr(write_addr, cmd, flash->addr_width);
 
 		debug("SF: 0x%p => cmd = { 0x%02x 0x%02x%02x%02x } chunk_len = %zu\n",
 		      buf + actual, cmd[0], cmd[1], cmd[2], cmd[3], chunk_len);
 
-		ret = spi_flash_write_common(flash, cmd, sizeof(cmd),
+		ret = spi_flash_write_common(flash, cmd, flash->addr_width + 1,
 					buf + actual, chunk_len);
 		if (ret < 0) {
 			debug("SF: write failed\n");
@@ -492,7 +500,7 @@ int spi_flash_cmd_read_ops(struct spi_flash *flash, u32 offset,
 		return 0;
 	}
 
-	cmdsz = SPI_FLASH_CMD_LEN + flash->dummy_byte;
+	cmdsz = flash->addr_width + 1 + flash->dummy_byte;
 	cmd = calloc(1, cmdsz);
 	if (!cmd) {
 		debug("SF: Failed to allocate cmd\n");
@@ -520,7 +528,7 @@ int spi_flash_cmd_read_ops(struct spi_flash *flash, u32 offset,
 		else
 			read_len = remain_len;
 
-		spi_flash_addr(read_addr, cmd);
+		spi_flash_addr(read_addr, cmd, flash->addr_width);
 
 		ret = spi_flash_read_common(flash, cmd, cmdsz, data, read_len);
 		if (ret < 0) {
@@ -1154,6 +1162,10 @@ int spi_flash_scan(struct spi_flash *flash)
 	if (flash->dual_flash & SF_DUAL_STACKED_FLASH)
 		flash->size <<= 1;
 #endif
+	if (flash->size > SPI_FLASH_16MB_BOUN)
+		flash->addr_width = 4;
+	else
+		flash->addr_width = 3;
 
 #ifdef CONFIG_SPI_FLASH_USE_4K_SECTORS
 	/* Compute erase sector and command */
diff --git a/include/spi_flash.h b/include/spi_flash.h
index be2fe3f84cb9..c65bf22aee8b 100644
--- a/include/spi_flash.h
+++ b/include/spi_flash.h
@@ -39,6 +39,7 @@ struct spi_slave;
  * @flags:		Indication of spi flash flags
  * @size:		Total flash size
  * @page_size:		Write (page) size
+ * @addr_width:		number of address bytes
  * @sector_size:	Sector size
  * @erase_size:		Erase size
  * @bank_read_cmd:	Bank read cmd
@@ -72,6 +73,7 @@ struct spi_flash {
 
 	u32 size;
 	u32 page_size;
+	u8 addr_width;
 	u32 sector_size;
 	u32 erase_size;
 #ifdef CONFIG_SPI_FLASH_BAR
-- 
2.10.0.479.g7c56b16