[U-Boot] [RFC PATCH 4/4 v3] mtd: sf: Add CONFIG_SPI_N25Q256A_RESET for software-reset

[Stefan Roese]

This is needed for the SoCFPGA booting from SPI NOR flash
e.g. (N25Q256A). With these changes, the SoCrates can boot and
re-boot (reset) from SPI NOR flash without any problems.

Signed-off-by: Stefan Roese <sr at denx.de>
Cc: Chin Liang See <clsee at altera.com>
Cc: Dinh Nguyen <dinguyen at altera.com>
Cc: Vince Bridgers <vbridger at altera.com>
Cc: Marek Vasut <marex at denx.de>
Cc: Pavel Machek <pavel at denx.de>
Cc: Michael Trimarchi <michael at amarulasolutions.com>
Cc: Jagannadha Sutradharudu Teki <jagannadh.teki at gmail.com>
---
 drivers/mtd/spi/sf_probe.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/mtd/spi/sf_probe.c b/drivers/mtd/spi/sf_probe.c
index 4d148d1..85b2677 100644
--- a/drivers/mtd/spi/sf_probe.c
+++ b/drivers/mtd/spi/sf_probe.c
@@ -355,6 +355,37 @@ static struct spi_flash *spi_flash_probe_slave(struct spi_slave *spi)
 		}
 	}
 
+#ifdef CONFIG_SPI_N25Q256A_RESET
+#define CMD_RESET_ENABLE	0x66
+#define CMD_RESET_MEMORY	0x99
+	/*
+	 * This is needed for the SoCFPGA booting from SPI NOR flash
+	 * e.g. (N25Q256A). Additionally its necessary to change
+	 * this line in the Linux SPI NOR flash driver:
+	 *
+	 * { "n25q256a",    INFO(0x20ba19, 0, 64 * 1024,  512,
+	 *    SECT_4K | SHUTDOWN_3BYTE) },
+	 *
+	 * Add SHUTDOWN_3BYTE here.
+	 *
+	 * With these changes, the SoCrates can boot and re-boot
+	 * (reset) from SPI NOR flash without any problems.
+	 */
+	ret = spi_flash_cmd(spi, CMD_RESET_ENABLE, NULL, 0);
+	if (ret) {
+		printf("SF: Failed issue reset command\n");
+		goto err_read_id;
+	}
+
+	ret = spi_flash_cmd(spi, CMD_RESET_MEMORY, NULL, 0);
+	if (ret) {
+		printf("SF: Failed issue reset command\n");
+		goto err_read_id;
+	}
+
+	printf("SF: Device software reset\n");
+#endif
+
 #ifdef CONFIG_OF_CONTROL
 	if (spi_flash_decode_fdt(gd->fdt_blob, flash)) {
 		debug("SF: FDT decode error\n");
-- 
2.1.1