bootdisc.c

bootloader源代码

/*****************************************
 Copyright (c) 2001-2002 
 Sigma Designs, Inc. All Rights Reserved
 Proprietary and Confidential
 *****************************************/

/* This is file is part of the Jasper DVD boot loader */

#include "config.h"

#ifdef SUPPORT_BOOT_FROM_CD

#include "atapi.h"
#include "errors.h"
#include "uart.h"
#include "fipuser.h"

unsigned char sector_buffer[2048]; 

static int stringcmp(const char *s1, const char *s2, int n)
{
	int i=0;
	while(s1[i] == s2[i]) {		
		if(s2[i]==0 || i>=n-1) {
			return 1;  // same string
		}	       
		i++; 
	}
	// different strings
	return 0;
}

static void set_disc_boot_status(int st)
{
	if(st == BOOT_STATUS_ATAPIERROR)
		boot_status |= st;
	else
		boot_status = (boot_status & ~BOOT_STATUS_DISC_MASK) | st;
}

// Read a (possibly unaligned) 32 bit value
unsigned int read_dword(unsigned char *buf)
{
	unsigned int r;

	r= (unsigned int)( (buf[0]      )|
			   (buf[1] <<  8)|
			   (buf[2] << 16)|
			   (buf[3] << 24) );
	return r;
}

// Read a (possibly unaligned) 16 bit value
unsigned short read_word(unsigned char *buf)
{
	return (unsigned short)( (buf[0]      )|
				 (buf[1] >>  8) );
}

// Read 'count' sectors starting from 'addr' into 'buffer'
unsigned int read_sectors(unsigned char *buffer, unsigned int addr,
			 unsigned short count)
{
	PrintLong(addr);
	PrintUart(" : read_sectors\r\n",25);

	if(IdeReadSectors(buffer, addr, count)){
		PrintUart("Read Sectors FAILED\r\n",30);
		return 0;
	} else {
		PrintUart("Read Sectors OK\r\n",30);
		return 1;
	}
}

// Detect if we have a valid disc here
unsigned int detect_disc()
{       
	if(IdeWaitReady(5000000)!=0)  
		return 0;  // failed
	else
		return 1;
}

// Check boot record validity and return boot catalog address
unsigned int read_boot_record(unsigned char *buf)
{
	if(buf[0]!=0 || buf[6]!=1) {
		PrintUart("BOOT RECORD: Wrong ID or Version\r\n",40);
		return 0; // wrong Id or version
	}
	      
	if(!stringcmp(buf+1, "CD001",5)) {
			PrintUart("BOOT RECORD: Wrong ISOID\r\n",40);
			PrintUart(buf+1,6);
			PrintUart("\r\n",6);
			return 0; // wrong isoid
	}

	if(!stringcmp(buf+7, "EL TORITO SPECIFICATION",24)) {
		PrintUart("BOOT RECORD: Wrong ELTORITOID\r\n",40);
		return 0; // wrong el torito id
	}
       
	return read_dword(buf+0x47);	
}

// check validation entry
unsigned int check_validation_entry(unsigned char *buf)
{	
	if(buf[0]!=1)
		return 0;

#ifdef ELTORITO_PLATFORM_ID
	if(buf[1]!=ELTORITO_PLATFORM_ID) { // check platform ID
		PrintUart("WRONG PLATFORM ID\r\n",40);
		return 0;  
	}
#endif
#ifdef ELTORITO_ID_STRING
	if(!stringcmp(buf+4,ELTORITO_ID_STRING,26)) {
		PrintUart("WRONG ID STRING",40);
		PrintUart(buf+4,40);
		return 0;
	}
#endif
	if((buf[0x1e]!=0x55) || (buf[0x1f]!=0xaa))
		return 0;

// FIXME - need to check more - crc and stuff
	return 1;
}

// read initial entry and get image addr and size
unsigned int get_initial_entry(unsigned char *buf, unsigned int *addr,
			       unsigned int *count)
{
	if(buf[0]!=0x88) {
		PrintUart("DEFAULT ENTRY: Not bootable\r\n",40);
		return 0; // Non bootable or wrong indicator
	}

/* Optionnal: check the emulation type */	
	if(buf[1]!=0)     // Emulation shoudl be set to No Emulation
		return 0; // Unsupported emulation?
	
	*count=read_word(buf+6);
	*addr=read_dword(buf+8);

	
/* Optionnal: return the load segment value
	return ((unsigned int)read_word(buf+2))<<4)
*/
	return 1;
}

// Load the image from disc into sdram
// XXX FIXME - Sector size ? When to use 2048 and when to use 512 (logical)
unsigned int load_image(unsigned int image_addr,
			unsigned int kload,
			unsigned short image_count)
{
	return read_sectors((char *)kload, image_addr, image_count);
}

// Main routine to boot from CD
// Try to locate a bootable image on the CD and load it at 'kload'
unsigned int try_boot_disc(unsigned int kload) 
{
	unsigned int catalog_addr;
	unsigned int image_addr;
	unsigned int image_count;

	PrintUart("Detect the disc\r\n",30);
	// Is there an ISO disc ?
	if(!detect_disc()) {
		fip_display_text(FIP_TEXT_NO_DISC);
		PrintUart("No disc\r\n",30);
		set_disc_boot_status(BOOT_STATUS_NODISC);
		return 0;
	}
       
	PrintUart("Disc Present\r\n",20);
	fip_display_text(FIP_TEXT_LOADING);

	// Read Boot Record Volume Descriptor (sector 17)
	if(!read_sectors(sector_buffer, 17, 1)){
		set_disc_boot_status(BOOT_STATUS_BOOTRECORD
				| BOOT_STATUS_ATAPIERROR);
		return 0;
	}
	
	PrintUart("Boot Record Sector Read\r\n",30);

	// Get booting catalog address
	catalog_addr=read_boot_record(sector_buffer);
	PrintUart("\r\n",4);
	PrintLong(catalog_addr);
	PrintUart("\r\n",4);
	if(!catalog_addr) {
		set_disc_boot_status(BOOT_STATUS_BOOTRECORD);
		return 0;
	}
		
	PrintUart("Boot Record OK\r\n",20);

	// Read booting catalog
	if(!read_sectors(sector_buffer, catalog_addr, 1)){
		set_disc_boot_status(BOOT_STATUS_BOOTCATALOG 
				| BOOT_STATUS_ATAPIERROR);
		return 0;
	}
	
	PrintUart("Read Boot Catalog sector\r\n",40);

	// Check validation entry
	if(!check_validation_entry(sector_buffer)) {
		set_disc_boot_status(BOOT_STATUS_VALIDATION);
		return 0;
	}

	PrintUart("Validation Entry OK\r\n",30);

	// Get initial image address and size
	if(!get_initial_entry(sector_buffer+0x20,&image_addr, &image_count)) {
		set_disc_boot_status(BOOT_STATUS_ENTRY);
		return 0;
	}

	PrintUart("Found Initial Entry\r\n",30);
	PrintLong(image_addr);
	PrintUart(" address to load\r\n",30);
	PrintLong(image_count);
	PrintUart(" sectors to load (but using 512)\r\n",40);
	image_count=512; 

	// Copy the image from CD to SDRAM
	if(!load_image(image_addr, kload, image_count))
		set_disc_boot_status(BOOT_STATUS_DISCLOAD);
	
	PrintUart("Loaded Image\r\n",30);
	
	set_disc_boot_status(BOOT_STATUS_OK);		
	return 1;
}

#endif // SUPPORT_BOOT_FROM_CD