sf: Discover read dummy_byte

Discovered the read dummy_byte based on the
configured read command.

Signed-off-by: Jagannadha Sutradharudu Teki <jaganna@xilinx.com>

drivers/mtd/spi/sf_internal.h

@@ -10,6 +10,8 @@
 #ifndef _SF_INTERNAL_H_
 #define _SF_INTERNAL_H_
 
+#define SPI_FLASH_3B_ADDR_LEN		3
+#define SPI_FLASH_CMD_LEN		(1 + SPI_FLASH_3B_ADDR_LEN)
 #define SPI_FLASH_16MB_BOUN		0x1000000
 
 /* CFI Manufacture ID's */

drivers/mtd/spi/sf_ops.c

@@ -9,6 +9,7 @@
  */
 
 #include <common.h>
+#include <malloc.h>
 #include <spi.h>
 #include <spi_flash.h>
 #include <watchdog.h>
@@ -216,7 +217,7 @@ int spi_flash_write_common(struct spi_flash *flash, const u8 *cmd,
 int spi_flash_cmd_erase_ops(struct spi_flash *flash, u32 offset, size_t len)
 {
 	u32 erase_size;
-	u8 cmd[4];
+	u8 cmd[SPI_FLASH_CMD_LEN];
 	int ret = -1;
 
 	erase_size = flash->erase_size;
@@ -255,7 +256,7 @@ int spi_flash_cmd_write_ops(struct spi_flash *flash, u32 offset,
 {
 	unsigned long byte_addr, page_size;
 	size_t chunk_len, actual;
-	u8 cmd[4];
+	u8 cmd[SPI_FLASH_CMD_LEN];
 	int ret = -1;
 
 	page_size = flash->page_size;
@@ -317,7 +318,7 @@ int spi_flash_read_common(struct spi_flash *flash, const u8 *cmd,
 int spi_flash_cmd_read_ops(struct spi_flash *flash, u32 offset,
 		size_t len, void *data)
 {
-	u8 cmd[5], bank_sel = 0;
+	u8 *cmd, cmdsz, bank_sel = 0;
 	u32 remain_len, read_len;
 	int ret = -1;
 
@@ -335,9 +336,11 @@ int spi_flash_cmd_read_ops(struct spi_flash *flash, u32 offset,
 		return 0;
 	}
 
-	cmd[0] = flash->read_cmd;
-	cmd[4] = 0x00;
+	cmdsz = SPI_FLASH_CMD_LEN + flash->dummy_byte;
+	cmd = malloc(cmdsz);
+	memset(cmd, 0, cmdsz);
 
+	cmd[0] = flash->read_cmd;
 	while (len) {
 #ifdef CONFIG_SPI_FLASH_BAR
 		bank_sel = offset / SPI_FLASH_16MB_BOUN;
@@ -356,8 +359,7 @@ int spi_flash_cmd_read_ops(struct spi_flash *flash, u32 offset,
 
 		spi_flash_addr(offset, cmd);
 
-		ret = spi_flash_read_common(flash, cmd, sizeof(cmd),
-							data, read_len);
+		ret = spi_flash_read_common(flash, cmd, cmdsz, data, read_len);
 		if (ret < 0) {
 			debug("SF: read failed\n");
 			break;

drivers/mtd/spi/sf_probe.c

@@ -140,6 +140,25 @@ static struct spi_flash *spi_flash_validate_params(struct spi_slave *spi,
 		}
 	}
 
+	/* Read dummy_byte: dummy byte is determined based on the
+	 * dummy cycles of a particular command.
+	 * Fast commands - dummy_byte = dummy_cycles/8
+	 * I/O commands- dummy_byte = (dummy_cycles * no.of lines)/8
+	 * For I/O commands except cmd[0] everything goes on no.of lines
+	 * based on particular command but incase of fast commands except
+	 * data all go on single line irrespective of command.
+	 */
+	switch (flash->read_cmd) {
+	case CMD_READ_QUAD_IO_FAST:
+		flash->dummy_byte = 2;
+		break;
+	case CMD_READ_ARRAY_SLOW:
+		flash->dummy_byte = 0;
+		break;
+	default:
+		flash->dummy_byte = 1;
+	}
+
 	/* Poll cmd seclection */
 	flash->poll_cmd = CMD_READ_STATUS;
 #ifdef CONFIG_SPI_FLASH_STMICRO

include/spi_flash.h

@@ -72,6 +72,7 @@ extern const struct spi_flash_params spi_flash_params_table[];
  * @erase_cmd:		Erase cmd 4K, 32K, 64K
  * @read_cmd:		Read cmd - Array Fast, Extn read and quad read.
  * @write_cmd:		Write cmd - page and quad program.
+ * @dummy_byte:		Dummy cycles for read operation.
  * @memory_map:		Address of read-only SPI flash access
  * @read:		Flash read ops: Read len bytes at offset into buf
  *			Supported cmds: Fast Array Read
@@ -98,6 +99,7 @@ struct spi_flash {
 	u8 erase_cmd;
 	u8 read_cmd;
 	u8 write_cmd;
+	u8 dummy_byte;
 
 	void *memory_map;
 	int (*read)(struct spi_flash *flash, u32 offset, size_t len, void *buf);