[U-Boot] Dynamically sized CFI flash.

[Jon Smirl]

I'm porting support for a Phytec PCM030 (mpc5200) from 1.2 up to
current head so that I can get it merged.  These boards can be
populated with a variety of flash chips, there is code to compute the
size of these chips and fix up bank_base[] in cfi_flash.c In u-boot
1.3.4 bank_base[] was rewritten.  What is the correct way to do these
calculations?

extern ulong bank_base[CFG_MAX_FLASH_BANKS];

int board_early_init_r (void)
{
	int width, id;
	ulong mb, dev_size;
	ulong base = 0xff000000;
	ulong lpb;

	lpb = *(vu_long *)MPC5XXX_LPB;

	*(vu_long *)MPC5XXX_BOOTCS_START = START_REG(base);
	*(vu_long *)MPC5XXX_BOOTCS_STOP = STOP_REG(base, 16 * 1024 * 1024);
	/*
	 * we run the PCI bus with 33 1/3 MHz. The flash requires 75ns accesstime.
	 * 2 base waitstates plus one additional waitstate makes the access as fast
	 * as possible (=90ns)
	 */
	lpb &=  0x0000dfc0; /* make it writable and mask out wait stages */
	lpb |=  0x0001d000; /* adjust wait stages */
	*(vu_long *)MPC5XXX_LPB = lpb;

	/* get flash width */
	width = (lpb >> 8) & 0x3;

	switch (width) {
	case 0: /* 8 bit */
		*(vu_char *)base = 0x90;
		id = *(vu_char *)(base + 3);
		*(vu_char *)base = 0xff;
		break;
	case 1: /* 16 bit */
		*(vu_short *)base = 0x90;
		id = *(vu_short *)(base + 2) & 0xff;
		*(vu_short *)base = 0xff;
		break;
	case 3: /* 32 bit */
		*(vu_short *)base = 0x90;
		id = *(vu_short *)(base + 4) & 0xff;
		*(vu_short *)base = 0xff;
		break;
	}

	switch (id) {
	case 0x16:
		mb = 4;
		break;
	case 0x17:
		mb = 8;
		break;
	case 0x18:
		mb = 16;
		break;
	case 0x20:
		mb = 8;
		break;
	case 0x21:
		mb = 16;
		break;
	case 0x22:
		mb = 32;
		break;
	}

	/* On these boards everything which is 32bit wide consists
	 * of two 16bit Flashes
	 */
	if (width == 3)
		mb <<= 1;

	/*
	 * On this platform one chip select can only handle up to 32MiB.
	 * So we must limit boot cs's baseaddress to 0xfe000000 and above
         */
	if (mb > 32)
		dev_size = 32;
	else
		dev_size = mb;

	*(vu_long *)MPC5XXX_BOOTCS_START = START_REG(0x0u - (dev_size << 20));
	*(vu_long *)MPC5XXX_BOOTCS_STOP = STOP_REG(0x0u - (dev_size << 20),
(dev_size << 20));

        /*
	 * the developer is responsible to setup other chip select lines to
	 * reach other parts of the device if its larger than 32MiB
	 */
	bank_base[0] = 0x0u - (mb << 20);

	return 0;
}



-- 
Jon Smirl
jonsmirl at gmail.com