bootblk.c

umon bootloader source code, support mips cpu.

/* bootblock.c:
 *	This is a single file that contains snippets of code from other portions
 *	of the monitor.  The snippets are duplicated so that no unnecessary
 *	code is included in this bootblock code.
 *	Its purpose is to exist in the HARDWARE-WRITE-PROTECTED boot sector of
 *	system flash (the point into which the CPU jumps when a reset exception
 *	is taken).  It runs a crc32 on the monitors flash space prior to jumping
 *	into it.  If the crc32 passes, then this bootblock code jumps into the
 *	entrypoint of the monitor and the monitor starts up as it normally would;
 *	if the crc32 fails, then an error message is dumped out the serial port
 *	and XMODEM is automatically started.  The XMODEM downloader will wait
 *	forever for a load from the target, and upon completion of that download,
 *	that code is jumped into and assumed to be some temporary version of the
 *	monitor that can execute out of RAM and rebuild the flash.
 *
 *	The sanity test is based on a table that is assumed to be located at the
 *	base of the monitor flash....
 *
 *					------------------------------
 *				   | CRC32 Start Address.        |
 *					------------------------------
 *				   | CRC32 Size.                 |
 *					------------------------------
 *				   | Result of CRC32.            |
 *					------------------------------
 *				   | Entrypoint into monitor.    |
 *					------------------------------
 *
 *	This code does assume that there are some basic UART functions external
 *	to this file.  The default for this would be to just link in the cpuio.c
 *	that is in the target-specific directory, or create a BOOTBLOCK version
 *	of the cpuio.c that is more compact.
 *
 *	IMPORTANT NOTE:
 *	This is meant to be a small stand-alone block of code that is in a
 *	HARDWARE-WRITE-PROTECTED boot sector of the flash.  This point is 
 *	emphasized because if the sector is not hardware protected, then there is
 *	no point in using this bootblock code.  The monitor has its own software
 *	hooks to do the best job it can to avoid "accidental" overwrites of 
 *	critical flash space and the space owned by TFS has its own CRC32 
 *	corruption detection.  The point of this bootblock is to provide a
 *	fail-safe fallback just in case the monitor itself (not TFS) somehow
 *	becomes corrupted.  This can only be guaranteed if the bootblock is
 *	protected by hardware.
 *
 *	General notice:
 *	This code is part of a boot-monitor package developed as a generic base
 *	platform for embedded system designs.  As such, it is likely to be
 *	distributed to various projects beyond the control of the original
 *	author.  Please notify the author of any enhancements made or bugs found
 *	so that all may benefit from the changes.  In addition, notification back
 *	to the author will allow the new user to pick up changes that may have
 *	been made by other users after this version of the code was distributed.
 *
 *	Note1: the majority of this code was edited with 4-space tabs.
 *	Note2: as more and more contributions are accepted, the term "author"
 *		   is becoming a mis-representation of credit.
 *
 *	Original author:	Ed Sutter
 *	Email:				[e-mail]
 *	Phone:				[phone]
 */

#include "stddefs.h"

struct bootinfo {
	uchar	*crcstart;
	ulong	crcsize;
	ulong	crcvalue;
	void	(*entrypoint)();
};

#define XNULL	0
#define XUP	1
#define XDOWN	2

#define SOH	0x01
#define EOT	0x04
#define ACK	0x06
#define NAK	0x15
#define CAN	0x18
#define ESC	0x1b

#define PKTLEN	128

/* prString():
 *	Print the incoming string as is.
 */
void
prString(char *str)
{
	if (str) {
		while(*str)
			rputchar(*str++);
	}
}

/* prHex():
 *	Feed this function a pointer to binary data and it will print it in
 *	ascii hex.
 */
void
prHex(char *prefix, int size,uchar *cp, char *suffix)
{
	int		i;
	uchar	*end;
	static	char *hexdigits = "0123456789abcdef";

	prString(prefix);
	prString("0x");
	end = cp + size;
	while(cp < end) {
		rputchar(hexdigits[(int)((*cp&0xf0)>>4)]);
		rputchar(hexdigits[(int)(*cp&0x0f)]);
		cp++;
	}
	prString(suffix);
}

int
getbytes(char *buf,int cnt)
{
	int	i;

	for(i=0;i<cnt;i++) {
		while(!gotachar());
		buf[i] = (char)getchar();
	}
	return(i);
}

/* Xdown():
 *	Called when a transfer from host to target is being made (considered
 *	an download).
 */

int
Xdown(char *binaddress)
{
	volatile long	timeout;
	ushort	word;
	char	c, *pkt;
	int		done, i, pktcnt;
	uchar	csum, xcsum, sno, seq[2], *cp;

	pktcnt = 0;
	sno = 0x01;

	/* Startup synchronization... */
	/* Continuously send NAK until sender responds. */
	while(1) {
		rputchar(NAK);
		timeout = LoopsPerSecond;
		while(!gotachar() && timeout)
			timeout--;
		if (timeout)
			break;
	}

	done = 0;
	while(done == 0) {
		c = (char)getchar();
		switch(c) {
		case SOH:
			getbytes(seq,2);
			getbytes(binaddress,PKTLEN);
			xcsum = (uchar)getchar();
			csum = 0;
			pkt = (char *)binaddress;
			for(i=0;i<PKTLEN;i++)
				csum += *pkt++;
			if (csum != xcsum) {
				rputchar(CAN);
				done = -1;
				break;
			}
			if ((uchar)seq[0] !=  (uchar)sno) {
				rputchar(CAN);
				done = -1;
				break;
			}
			if ((uchar)seq[1] != (uchar) ~sno) {
				rputchar(CAN);
				done = -1;
				break;
			}
			cp = (uchar *)&word;
			binaddress += PKTLEN;
			sno++;
			pktcnt++;
			rputchar(ACK);
			break;
		case CAN:
			done = -1;
			break;
		case EOT:
			rputchar(ACK);
			done = pktcnt*PKTLEN;
			break;
		case ESC:		/* User-invoked abort */
			done = -1;
			break;
		default:
			done = -1;
			break;
		}
	}
	return(done);
}

/* crc32tab[]:
 *	Used for calculating a 32-bit CRC.
 */
unsigned long crc32tab[] = {
	0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F,
	0xE963A535, 0x9E6495A3, 0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, 
	0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91, 0x1DB71064, 0x6AB020F2,
	0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7, 
	0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9,
	0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172, 
	0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B, 0x35B5A8FA, 0x42B2986C,
	0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59, 
	0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423,
	0xCFBA9599, 0xB8BDA50F, 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, 
	0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, 0x76DC4190, 0x01DB7106,
	0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433, 
	0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D,
	0x91646C97, 0xE6635C01, 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 
	0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950,
	0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65, 
	0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7,
	0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0, 
	0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C, 0x270241AA,
	0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F, 
	0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81,
	0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, 
	0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683, 0xE3630B12, 0x94643B84,
	0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1, 
	0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB,
	0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC, 
	0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, 0xD6D6A3E8, 0xA1D1937E,
	0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B, 
	0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55,
	0x316E8EEF, 0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236, 
	0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, 0xC5BA3BBE, 0xB2BD0B28,
	0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D, 
	0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F,
	0x72076785, 0x05005713, 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 
	0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242,
	0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777, 
	0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69,
	0x616BFFD3, 0x166CCF45, 0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2, 
	0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC,
	0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9, 
	0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693,
	0x54DE5729, 0x23D967BF, 0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, 
	0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D
};

/* crc32(): */
ulong
crc32(uchar *buffer,ulong nbytes)
{
	int	temp;
	unsigned long crc_rslt;

	crc_rslt = 0xffffffff;
	while(nbytes) {
		temp = (crc_rslt ^ *buffer++) & 0x000000FFL;
		crc_rslt = ((crc_rslt >> 8) & 0x00FFFFFFL) ^ crc32tab[temp];
		nbytes--;
	}
	return(~crc_rslt);
}

/* main():
 *	This function would be called in place of the main() function that
 *	is in the target-specific code.  To keep things simple, this bbmain()
 *	does not want an argc/argv-like argument format, just pass the args
 *	directly (otherwise strtol would be needed).  It assumes that it is
 *	being called at the same point that start() would call main(), so
 *	basic initialization of the system (UART) can be assumed.
 *
 *	bip:	pointer to the location of the table that is supposed to contain
 *			the bootinfo structure.
 */
int
main(int argc, char *argv[])
{
	int	(*go)();
	struct bootinfo *bip;

	bip = (struct bootinfo *)(BOOTINFO_PTR);

	/* If the crcsize is greater than 1Mb, then assume a corrupt size and
	 * don't do the crc; otherwise, run the crc32 check...
	 */
	if (bip->crcsize < 0x100000) {
		if (crc32(bip->crcstart,bip->crcsize) == bip->crcvalue) {
			prHex("CRC passed, jumping into: ",4,
				(uchar *)&bip->entrypoint,"\r\n");
			bip->entrypoint();
		}
	}

	/* If we got here, then the boot-block test failed, so we need to run
	 * Xmodem and then jump into the entrypoint of the xmodem download...
	 */
	prHex("CRC failed using BIP: ",4,(uchar *)&bip,"\r\n");
	prHex("Begin xmodem dld at : ",4,(uchar *)&APPLICATION_RAMSTART,"\r\n");

	while (Xdown((char *)APPLICATION_RAMSTART) < 0)
		prString("xmodem failed, trying again...\r\n");

	/* If we got here, then the xmodem download was successful, so we can
	 * jump into the space that was just downloaded and hopefully this
	 * will allow the system flash to be rebuilt and sanity restored.
	 */

	prString("Transferring control to downloaded app...\r\n");
	go = (int(*)())APPLICATION_RAMSTART;
	go();
	return(0);
}