void __init ar5315_prom_init(void)
{
    u32 memsize, memcfg;

    is_5315 = 1;
    memcfg = sysRegRead(AR5315_MEM_CFG);
    memsize   = 1 + ((memcfg & SDRAM_DATA_WIDTH_M) >> SDRAM_DATA_WIDTH_S);
    memsize <<= 1 + ((memcfg & SDRAM_COL_WIDTH_M) >> SDRAM_COL_WIDTH_S);
    memsize <<= 1 + ((memcfg & SDRAM_ROW_WIDTH_M) >> SDRAM_ROW_WIDTH_S);
    memsize <<= 3;
    add_memory_region(0, memsize, BOOT_MEM_RAM);

    /* Initialize it to AR2315 for now. Real detection will be done
     * in ar5315_init_devices() */
    mips_machtype = MACH_ATHEROS_AR2315;
}