misc.c

嵌入式系统设计与实例开发源码

/*
 * BK Id: SCCS/s.misc.c 1.15 10/15/01 10:53:29 trini
 */
/*
 * Adapted for PowerPC by Gary Thomas
 *
 * Rewritten by Cort Dougan ([e-mail])
 * One day to be replaced by a single bootloader for chrp/prep/pmac. -- Cort
 */

#include <linux/config.h>
#include <linux/types.h>
#include "zlib.h"
#include <asm/residual.h>
#include <linux/elf.h>
#include <asm/page.h>
#include <asm/processor.h>
#include <asm/mmu.h>
#ifdef CONFIG_8xx
#include <asm/mpc8xx.h>
#endif
#ifdef CONFIG_8260
#include <asm/mpc8260.h>
#endif

#include "nonstdio.h"

/*
 * The following references are needed to cause the linker to pull in the
 * gzimage.o and rdimage.o files.  These object files are special,
 * since they get placed into the .gzimage and .rdimage ELF sections 
 * of the zvmlinux and zvmlinux.initrd files.
 */
extern char dummy_for_gzimage;
extern char dummy_for_rdimage;

/*
 * Please send me load/board info and such data for hardware not
 * listed here so I can keep track since things are getting tricky
 * with the different load addrs with different firmware.  This will
 * help to avoid breaking the load/boot process.
 * -- Cort
 */
char *avail_ram;
char *end_avail;

/* Because of the limited amount of memory on embedded, it presents
 * loading problems.  The biggest is that we load this boot program
 * into a relatively low memory address, and the Linux kernel Bss often
 * extends into this space when it get loaded.  When the kernel starts
 * and zeros the BSS space, it also writes over the information we
 * save here and pass to the kernel (command line and board info).
 * On these boards, we grab some known memory holes to hold this information.
 */
char	cmd_buf[256];
char	*cmd_line = cmd_buf;

/* We need to pass along a 'dummy' com_port. */
unsigned long com_port = 0;

/* This is the default cmdline that will be given to the user at boot time..
 * If none was specified at compile time, we'll give it one that should work.
 * -- Tom */
#ifdef CONFIG_CMDLINE_BOOL
char	compiled_string[] = CONFIG_CMDLINE;
#endif
char	ramroot_string[] = "root=/dev/ram";
char	netroot_string[] = "root=/dev/nfs rw";

bd_t hold_resid_buf;
bd_t *hold_residual = &hold_resid_buf;
unsigned long initrd_start = 0, initrd_end = 0;
char *zimage_start;

extern void gunzip(void *, int, unsigned char *, int *);

unsigned long
decompress_kernel(unsigned long load_addr, int num_words, unsigned long cksum, bd_t *bp)
{
	int timer, zimage_size = ZIMAGE_SIZE;
	extern unsigned long start;
	char *cp, ch;

#ifdef CONFIG_8260
	/* I don't know why I didn't do it this way on the 8xx.......
	*/
	embed_config(&bp);
	serial_init(bp);
#endif

	/* Grab some space for the command line and board info.  Since
	 * we no longer use the ELF header, but it was loaded, grab
	 * that space.
	 */
#ifdef CONFIG_MBX
	cmd_line = (char *)(load_addr - 0x10000);

	/* To be like everyone else, we need one too, although this
	 * board information is passed from the boot rom.
	 */
	bp->bi_baudrate = 9600;
#else
	cmd_line = (char *)(0x200000);
#endif
	hold_residual = (bd_t *)(cmd_line + sizeof(cmd_buf));
	/* copy board data */
	if (bp)
		memcpy(hold_residual,bp,sizeof(bd_t));

	/* Set end of memory available to us.  It is always the highest
	 * memory address provided by the board information.
	 */
	end_avail = (char *)(bp->bi_memsize);

	puts("loaded at:     "); puthex(load_addr);
	puts(" "); puthex((unsigned long)(load_addr + (4*num_words))); puts("\n");
	if ( (unsigned long)load_addr != (unsigned long)&start )
	{
		puts("relocated to:  "); puthex((unsigned long)&start);
		puts(" ");
		puthex((unsigned long)((unsigned long)&start + (4*num_words)));
		puts("\n");
	}

	if ( bp )
	{
		puts("board data at: "); puthex((unsigned long)bp);
		puts(" ");
		puthex((unsigned long)((unsigned long)bp + sizeof(bd_t)));
		puts("\n");
		puts("relocated to:  ");
		puthex((unsigned long)hold_residual);
		puts(" ");
		puthex((unsigned long)((unsigned long)hold_residual + sizeof(bd_t)));
		puts("\n");
	}

	/* we have to subtract 0x10000 here to correct for objdump including the
	   size of the elf header which we strip -- Cort */
	zimage_start = (char *)(load_addr - 0x10000 + ZIMAGE_OFFSET);

	if ( INITRD_OFFSET )
		initrd_start = load_addr - 0x10000 + INITRD_OFFSET;
	else
		initrd_start = 0;
	initrd_end = INITRD_SIZE + initrd_start;

	/*
	 * setup avail_ram - this is the first part of ram usable
	 * by the uncompress code. -- Cort
	 */
	avail_ram = (char *)PAGE_ALIGN((unsigned long)zimage_start+zimage_size);
	if ( ((load_addr+(num_words*4)) > (unsigned long) avail_ram)
		&& (load_addr <= 0x01000000) )
		avail_ram = (char *)(load_addr+(num_words*4));
	if ( (((unsigned long)&start+(num_words*4)) > (unsigned long) avail_ram)
		&& (load_addr <= 0x01000000) )
		avail_ram = (char *)((unsigned long)&start+(num_words*4));
	
	/* relocate zimage */
	puts("zimage at:     "); puthex((unsigned long)zimage_start);
	puts(" "); puthex((unsigned long)(zimage_size+zimage_start)); puts("\n");
	/*
	 * There is no reason (yet) to relocate zImage for embedded boards.
	 * To support boot from flash rom on 8xx embedded boards, I
	 * assume if zimage start is over 16M we are booting from flash.
	 * In this case, avilable ram will start just above the space we
	 * have allocated for the command buffer and board information.
	 */
	if ((unsigned long)zimage_start > 0x01000000)
		avail_ram = (char *)PAGE_ALIGN((unsigned long)hold_residual + sizeof(bd_t));

	/* relocate initrd */
	if ( initrd_start )
	{
		puts("initrd at:     "); puthex(initrd_start);
		puts(" "); puthex(initrd_end); puts("\n");

		/* We only have to relocate initrd if we find it is in Flash
		 * rom.  This is because the kernel thinks it can toss the
		 * pages into the free memory pool after it is done.  Use
		 * the same 16M test.
		 */
		if ((unsigned long)initrd_start > 0x01000000) {
			memcpy ((void *)PAGE_ALIGN(-PAGE_SIZE+(unsigned long)end_avail-INITRD_SIZE),
				(void *)initrd_start,
				INITRD_SIZE );
			initrd_start = PAGE_ALIGN(-PAGE_SIZE+(unsigned long)end_avail-INITRD_SIZE);
			initrd_end = initrd_start + INITRD_SIZE;
			end_avail = (char *)initrd_start;
			puts("relocated to:  "); puthex(initrd_start);
			puts(" "); puthex(initrd_end); puts("\n");
		}
		else {
			avail_ram = (char *)PAGE_ALIGN((unsigned long)initrd_end);
		}
	}


	puts("avail ram:     "); puthex((unsigned long)avail_ram); puts(" ");
	puthex((unsigned long)end_avail); puts("\n");
	puts("\nLinux/PPC load: ");
	timer = 0;
	cp = cmd_line;
	/* This is where we try and pick the right command line for booting.
	 * If we were given one at compile time, use it.  It Is Right.
	 * If we weren't, see if we have a ramdisk.  If so, thats root.
	 * When in doubt, give them the netroot (root=/dev/nfs rw) -- Tom */
#ifdef CONFIG_CMDLINE_BOOL
	memcpy (cmd_line, compiled_string, sizeof(compiled_string));
#else
	if (initrd_start)
		memcpy (cmd_line, ramroot_string, sizeof(ramroot_string));
	else
		memcpy (cmd_line, netroot_string, sizeof(netroot_string));
#endif
	while ( *cp ) putc(*cp++);
	while (timer++ < 5*1000) {
		if (tstc()) {
			while ((ch = getc()) != '\n' && ch != '\r') {
				if (ch == '\b' || ch == '\177') {
					if (cp != cmd_line) {
						cp--;
						puts("\b \b");
					}
				} else if (ch == '\030'		/* ^x */
					   || ch == '\025') {	/* ^u */
					while (cp != cmd_line) {
						cp--;
						puts("\b \b");
					}
				} else {
					*cp++ = ch;
					putc(ch);
				}
			}
			break;  /* Exit 'timer' loop */
		}
		udelay(1000);  /* 1 msec */
	}
	*cp = 0;
	puts("\nUncompressing Linux...");

	gunzip(0, 0x400000, zimage_start, &zimage_size);
	puts("done.\n");
	puts("Now booting the kernel\n");
	return (unsigned long)hold_residual;
}