Undrer S3C6410, Setting ARM cpu frequency 667MHz.

1. Undrer S3C6410, Setting ARM cpu frequency 667MHz
Because default freqency is 532MHz.
6410 CPU can run up to 667MHz, modiry Linux kernel source code:

/* arch/arm/plat-s3c64xx/s3c6400-clock.c */

void __init_or_cpufreq s3c6400_setup_clocks(void)
{
    /* ... */
    __raw_writel((__raw_readl(S3C_APLL_CON) & 0xfc00ffff) | (0x14d <<16), S3C_APLL_CON); /* wenxy test, 333*2 MHz */
    apll = s3c6400_get_pll(xtal, __raw_readl(S3C_APLL_CON));

    printk(KERN_INFO "Wenxy: S3C_APLL_CON value: 0x%x\n", (unsigned int)__raw_readl(S3C_APLL_CON));

    fclk = apll / GET_DIV(clkdiv0, S3C6410_CLKDIV0_ARM);

    printk(KERN_INFO "S3C64XX: PLL settings, A=%ld, M=%ld, E=%ld\n",
           apll, mpll, epll);
    /* ... */    
}

I setting register "APLL_CON / MPLL_CON" according to S3C6410X.pdf manual, page 141, 142.
The output frequency is calculated using the following equation:
FOUT = MDIV X FIN / (PDIV X 2SDIV)

2. Then compile new kernel image, run it.
[root@EmbedSky /]# cat /proc/cpuinfo
Processor       : ARMv6-compatible processor rev 6 (v6l)
BogoMIPS        : 665.19
Features        : swp half thumb fastmult vfp edsp java
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0xb76
CPU revision    : 6

Hardware        : SMDK6410
Revision        : 0000
Serial          : 0000000000000000
[root@EmbedSky /]#