From 2b468ef0e7959b703626b64c4d264ef822c9267a Mon Sep 17 00:00:00 2001 From: Elie De Brauwer Date: Tue, 17 Sep 2013 19:48:22 +0200 Subject: [PATCH] mtd: m25p80: Fix 4 byte addressing mode for Micron devices. According to the datasheet for Micron n25q256a (N25Q256A13ESF40F) 4-byte addressing mode should be entered as follows: To enter or exit the 4-byte address mode, the WRITE ENABLE command must be executed to set the write enable latch bit to 1. (Note: The WRITE ENABLE command must NOT be executed on the N25Q256A83ESF40x and N25Q256A83E1240x devices.) S# must be driven LOW. The effect of the command is immediate; after the command has been executed, the write enable latch bit is cleared to 0. Micron's portable way to perform this for all types of Micron flash is to first issue a write enable, then switch the addressing mode followed by a write disable to avoid leaving the flash in a write- able state. Signed-off-by: Elie De Brauwer [Brian: reworked a bit] Signed-off-by: Brian Norris Signed-off-by: David Woodhouse --- drivers/mtd/devices/m25p80.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c index 26b14f9fcac6..6bc9618af094 100644 --- a/drivers/mtd/devices/m25p80.c +++ b/drivers/mtd/devices/m25p80.c @@ -168,12 +168,25 @@ static inline int write_disable(struct m25p *flash) */ static inline int set_4byte(struct m25p *flash, u32 jedec_id, int enable) { + int status; + bool need_wren = false; + switch (JEDEC_MFR(jedec_id)) { - case CFI_MFR_MACRONIX: case CFI_MFR_ST: /* Micron, actually */ + /* Some Micron need WREN command; all will accept it */ + need_wren = true; + case CFI_MFR_MACRONIX: case 0xEF /* winbond */: + if (need_wren) + write_enable(flash); + flash->command[0] = enable ? OPCODE_EN4B : OPCODE_EX4B; - return spi_write(flash->spi, flash->command, 1); + status = spi_write(flash->spi, flash->command, 1); + + if (need_wren) + write_disable(flash); + + return status; default: /* Spansion style */ flash->command[0] = OPCODE_BRWR;