[U-Boot] [PATCH V6] sf: Turn SPI flash chip into 3-Byte address mode

[Zhiqiang Hou]

From: Hou Zhiqiang <B48286 at freescale.com>

For more than 16MiB SPI flash chips, there are 3-Byte and 4-Byte address
mode, and only the 3-Byte address mode is supported in U-Boot so far.
So, reset the SPI flash to 3-Byte address mode in probe to ensure the SPI
flash work correctly, because it may has been set to 4-Byte address mode
after warm boot.

Signed-off-by: Hou Zhiqiang <B48286 at freescale.com>
---
Tested on T1042RDB board.
V6:
    Add the spi_release_bus.
V5:
    1. Removed #ifdef for STMICRO.
    2. Add support for Spansion chips (>16MiB) switch to 3-Byte address mode.
V4:
    Split the the patch to 2 patches for clear FSR and SPI flash address mode.
V3:
    Generate the patch based on the latest tree git://git.denx.de/u-boot.git.
V2:
    Add the operation of enter 3 Byte address mode in probe.
V1:
    Based on git://git.denx.de/u-boot.git.
 drivers/mtd/spi/sf_internal.h |  7 +++++++
 drivers/mtd/spi/sf_ops.c      | 40 ++++++++++++++++++++++++++++++++++++++++
 drivers/mtd/spi/sf_probe.c    | 10 ++++++++++
 3 files changed, 57 insertions(+)

diff --git a/drivers/mtd/spi/sf_internal.h b/drivers/mtd/spi/sf_internal.h
index 1de1dac..9519bd8 100644
--- a/drivers/mtd/spi/sf_internal.h
+++ b/drivers/mtd/spi/sf_internal.h
@@ -75,6 +75,10 @@ enum {
 #define CMD_FLAG_STATUS			0x70
 #define CMD_CLEAR_FLAG_STATUS		0x50
 
+/* Used for Micron, Macronix and Winbond flashes */
+#define	CMD_ENTER_4B_ADDR		0xB7
+#define	CMD_EXIT_4B_ADDR		0xE9
+
 /* Read commands */
 #define CMD_READ_ARRAY_SLOW		0x03
 #define CMD_READ_ARRAY_FAST		0x0b
@@ -231,6 +235,9 @@ 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);
 
+int spi_flash_cmd_4B_addr_switch(struct spi_flash *flash,
+		int enable, u8 idcode0);
+
 #ifdef CONFIG_SPI_FLASH_MTD
 int spi_flash_mtd_register(struct spi_flash *flash);
 void spi_flash_mtd_unregister(void);
diff --git a/drivers/mtd/spi/sf_ops.c b/drivers/mtd/spi/sf_ops.c
index deebcab..de30c55 100644
--- a/drivers/mtd/spi/sf_ops.c
+++ b/drivers/mtd/spi/sf_ops.c
@@ -93,6 +93,46 @@ int spi_flash_cmd_write_config(struct spi_flash *flash, u8 wc)
 }
 #endif
 
+int spi_flash_cmd_4B_addr_switch(struct spi_flash *flash,
+				int enable, u8 idcode0)
+{
+	int ret;
+	u8 cmd, bar;
+	bool need_wren = false;
+
+	ret = spi_claim_bus(flash->spi);
+	if (ret) {
+		debug("SF: unable to claim SPI bus\n");
+		return ret;
+	}
+
+	switch (idcode0) {
+	case SPI_FLASH_CFI_MFR_STMICRO:
+		/* Some Micron need WREN command; all will accept it */
+		need_wren = true;
+	case SPI_FLASH_CFI_MFR_MACRONIX:
+	case SPI_FLASH_CFI_MFR_WINBOND:
+		if (need_wren)
+			spi_flash_cmd_write_enable(flash);
+
+		cmd = enable ? CMD_ENTER_4B_ADDR : CMD_EXIT_4B_ADDR;
+		ret = spi_flash_cmd(flash->spi, cmd, NULL, 0);
+		if (need_wren)
+			spi_flash_cmd_write_disable(flash);
+
+		break;
+	default:
+		/* Spansion style */
+		bar = enable << 7;
+		cmd = CMD_BANKADDR_BRWR;
+		ret = spi_flash_cmd_write(flash->spi, &cmd, 1, &bar, 1);
+	}
+
+	spi_release_bus(flash->spi);
+
+	return ret;
+}
+
 #ifdef CONFIG_SPI_FLASH_BAR
 static int spi_flash_cmd_bankaddr_write(struct spi_flash *flash, u8 bank_sel)
 {
diff --git a/drivers/mtd/spi/sf_probe.c b/drivers/mtd/spi/sf_probe.c
index e0283dc..3b204f8 100644
--- a/drivers/mtd/spi/sf_probe.c
+++ b/drivers/mtd/spi/sf_probe.c
@@ -170,6 +170,16 @@ static int spi_flash_validate_params(struct spi_slave *spi, u8 *idcode,
 	flash->page_size <<= flash->shift;
 	flash->sector_size = params->sector_size << flash->shift;
 	flash->size = flash->sector_size * params->nr_sectors << flash->shift;
+
+	/*
+	 * So far, the 4-byte address mode haven't been supported in U-Boot,
+	 * and make sure the chip (> 16MiB) in default 3-byte address mode,
+	 * in case of warm bootup, the chip was set to 4-byte mode in kernel.
+	 */
+	if (flash->size > SPI_FLASH_16MB_BOUN) {
+		if (spi_flash_cmd_4B_addr_switch(flash, false, idcode[0]) < 0)
+			debug("SF: enter 3B address mode failed\n");
+	}
 #ifdef CONFIG_SF_DUAL_FLASH
 	if (flash->dual_flash & SF_DUAL_STACKED_FLASH)
 		flash->size <<= 1;
-- 
2.1.0.27.g96db324