We had a problem detecting 8/16bit flash devices connected only via 8bits to the SoC for quite a while. Commit 239cb9d9 [mtd: cfi_flash: Fix CFI flash driver for 8-bit bus support] finally fixed this 8-bit bus support. But also broke some other boards using this cfi driver. So this patch had to be reverted.
I spotted a different, simpler approach for this 8-bit bus support on the barebox mailing list posted by Oleksij Rempel bug-track@fisher-privat.net:
http://www.spinics.net/lists/u-boot-v2/msg14687.html
Here the commit text:
" Many cfi chips support 16 and 8 bit modes. Most important difference is use of so called "Q15/A-1" pin. In 16bit mode this pin is used for data IO. In 8bit mode, it is an address input which add one more least significant bit (LSB). In this case we should shift all adresses by one: For example 0xaa << 1 = 0x154 "
This patch now is a port of this barebox patch to U-Boot.
Along with the change w.r.t from barebox, Some flash chips can support multiple bus widths, override the interface width and limit it to the port width.
Tested on 16-bit Spansion flash on sequoia. Tested 8-bit flashes like 256M29EW, 512M29EW.
Signed-off-by: Stefan Roese sr@denx.de Tested-by: Jagannadha Sutradharudu Teki jaganna@xilinx.com --- drivers/mtd/cfi_flash.c | 37 +++++++++++++++++++++++++++++++++---- include/flash.h | 2 ++ 2 files changed, 35 insertions(+), 4 deletions(-)
diff --git a/drivers/mtd/cfi_flash.c b/drivers/mtd/cfi_flash.c index 22d8440..e23e394 100644 --- a/drivers/mtd/cfi_flash.c +++ b/drivers/mtd/cfi_flash.c @@ -212,7 +212,7 @@ flash_map (flash_info_t * info, flash_sect_t sect, uint offset) { unsigned int byte_offset = offset * info->portwidth;
- return (void *)(info->start[sect] + byte_offset); + return (void *)(info->start[sect] + (byte_offset << info->chip_lsb)); }
static inline void flash_unmap(flash_info_t *info, flash_sect_t sect, @@ -1892,12 +1892,27 @@ static int __flash_detect_cfi (flash_info_t * info, struct cfi_qry *qry) flash_read_cfi(info, qry, FLASH_OFFSET_CFI_RESP, sizeof(struct cfi_qry)); info->interface = le16_to_cpu(qry->interface_desc); + /* Some flash chips can support multiple bus widths. + * In this case, override the interface width and + * limit it to the port width. + */ + if ((info->interface == FLASH_CFI_X8X16) && + (info->portwidth == FLASH_CFI_8BIT)) { + debug("Overriding 16-bit interface width to" + " 8-bit port width\n"); + info->interface = FLASH_CFI_X8; + } else if ((info->interface == FLASH_CFI_X16X32) && + (info->portwidth == FLASH_CFI_16BIT)) { + debug("Overriding 16-bit interface width to" + " 16-bit port width\n"); + info->interface = FLASH_CFI_X16; + }
info->cfi_offset = flash_offset_cfi[cfi_offset]; debug ("device interface is %d\n", info->interface); - debug ("found port %d chip %d ", - info->portwidth, info->chipwidth); + debug("found port %d chip %d chip_lsb %d ", + info->portwidth, info->chipwidth, info->chip_lsb); debug ("port %d bits chip %d bits\n", info->portwidth << CFI_FLASH_SHIFT_WIDTH, info->chipwidth << CFI_FLASH_SHIFT_WIDTH); @@ -1937,9 +1952,23 @@ static int flash_detect_cfi (flash_info_t * info, struct cfi_qry *qry) info->portwidth <= FLASH_CFI_64BIT; info->portwidth <<= 1) { for (info->chipwidth = FLASH_CFI_BY8; info->chipwidth <= info->portwidth; - info->chipwidth <<= 1) + info->chipwidth <<= 1) { + /* + * First, try detection without shifting the addresses + * for 8bit devices (16bit wide connection) + */ + info->chip_lsb = 0; + if (__flash_detect_cfi(info, qry)) + return 1; + + /* + * Not detected, so let's try with shifting + * for 8bit devices + */ + info->chip_lsb = 1; if (__flash_detect_cfi(info, qry)) return 1; + } } debug ("not found\n"); return 0; diff --git a/include/flash.h b/include/flash.h index c7acc97..af2fe41 100644 --- a/include/flash.h +++ b/include/flash.h @@ -38,6 +38,8 @@ typedef struct { #ifdef CONFIG_SYS_FLASH_CFI uchar portwidth; /* the width of the port */ uchar chipwidth; /* the width of the chip */ + uchar chip_lsb; /* extra Least Significant Bit in the */ + /* address of chip */ ushort buffer_size; /* # of bytes in write buffer */ ulong erase_blk_tout; /* maximum block erase timeout */ ulong write_tout; /* maximum write timeout */