Flash Mapping and gpio

Fundu fundu_1999 at yahoo.com
Thu Sep 11 16:52:31 EDT 2008


I trying to access 256mb flash from a pripheral that can only access 128 mb.
flash are in x16 mode and interleaved.
A gpio is connected to A25 pin of the flash parts.

Such that any of the two 128mb "areas" can be accessed.

I'm trying to configure the mtd drivers such that i can do the following 

so when ofs 00000000 -> 07ffffff, A25(gpio)= 0
ofs 08000000 -> 0fffffff, A25(gpio) =1

i have added helper the following function in include/linux/cfi.h

#define GPIO_FLASH_MASK 0x00000800
static inline void flash_cs(u32 addr, char is_ret)
    u32 gpio_data = is_ret ? 0 : GPIO_FLASH_MASK;
    if (addr & 0x08000000)
        ibm_gpio_out(0, GPIO_FLASH_MASK, gpio_data);

/* adjust the ofs such that 0800_0000 seems like 0000_0000 */
static inline u32 update_addr(u32 addr)
    return (addr & 0x08000000) ? (addr - 0x08000000) : addr;

static inline void cfi_write(struct map_info *map, cfi_word val, __u32 addr)
    flash_cs(map->phys + addr, 0);
    u32 new_addr = update_addr(addr);

    cfi_write_o(map, val, new_addr);

    flash_cs(map->phys + addr, 1); // sets A25 back to 0

static inline cfi_word cfi_read(struct map_info *map, __u32 addr)
    flash_cs(map->phys + addr, 0);
    u32 new_addr = update_addr(addr);

    cfi_word returnVal = cfi_read_o(map, new_addr);

    flash_cs(map->phys + addr, 1); // sets A25 back to 0

    return returnVal;

cfi_read_o and cfi_write_o are the original fn.

Also in cfi_send_gen_cmd i don't call the modified cfi_write 
as all Commands go to base address which is 0.

there are 2 things that i'm seeing that doesn't make sense
in cfi_probe.c the print_cfi_ident prints the following

Typical byte/word write timeout: 64 us
Maximum byte/word write timeout: 512 us
Typical full buffer write timeout: 64 us
Maximum full buffer write timeout: 2048 us
Typical block erase timeout: 512 ms
Maximum block erase timeout: 4096 ms
Typical chip erase timeout: 524288 ms
Maximum chip erase timeout: 2097152 ms
Device size: 0x8000000 bytes (128 MiB)
Flash Device Interface description: 0x0002

1) which seems wrong as the Device size should come out to be 256 instead of 128.
This doesn't look right, any ideas ? 

other is that when i do a erase i'm seeing a this ...
MTD do_erase_oneblock(): Wacky!  Unable to decode failure status
MTD do_erase_oneblock(): 0x07f40000(0x00ff00ff): 0x27051956 0x27051956 0x27051956 0x27051956

thanks !


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