// SPDX-License-Identifier: GPL-2.0+
/*
 * (C) Copyright 2000-2004
 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 */

/*
 * Serial up- and download support
 */
#include <command.h>
#include <console.h>
#include <cpu_func.h>
#include <efi_loader.h>
#include <env.h>
#include <exports.h>
#ifdef CONFIG_MTD_NOR_FLASH
#include <flash.h>
#endif
#include <image.h>
#include <lmb.h>
#include <mapmem.h>
#include <net.h>
#include <s_record.h>
#include <serial.h>
#include <xyzModem.h>
#include <asm/cache.h>
#include <asm/global_data.h>
#include <linux/delay.h>

DECLARE_GLOBAL_DATA_PTR;

#if defined(CONFIG_CMD_LOADB)
static ulong load_serial_ymodem(ulong offset, int mode);
#endif

#if defined(CONFIG_CMD_LOADS)
static ulong load_serial(long offset);
static int read_record(char *buf, ulong len);
# if defined(CONFIG_CMD_SAVES)
static int save_serial(ulong offset, ulong size);
static int write_record(char *buf);
#endif

static int do_echo = 1;
#endif

/* -------------------------------------------------------------------- */

#if defined(CONFIG_CMD_LOADS)
static int do_load_serial(struct cmd_tbl *cmdtp, int flag, int argc,
			  char *const argv[])
{
	long offset = 0;
	ulong addr;
	int i;
	char *env_echo;
	int rcode = 0;
#ifdef	CONFIG_SYS_LOADS_BAUD_CHANGE
	int load_baudrate, current_baudrate;

	load_baudrate = current_baudrate = gd->baudrate;
#endif

	env_echo = env_get("loads_echo");
	if (env_echo && *env_echo == '1')
		do_echo = 1;
	else
		do_echo = 0;

#ifdef	CONFIG_SYS_LOADS_BAUD_CHANGE
	if (argc >= 2) {
		offset = simple_strtol(argv[1], NULL, 16);
	}
	if (argc == 3) {
		load_baudrate = (int)dectoul(argv[2], NULL);

		/* default to current baudrate */
		if (load_baudrate == 0)
			load_baudrate = current_baudrate;
	}
	if (load_baudrate != current_baudrate) {
		printf("## Switch baudrate to %d bps and press ENTER ...\n",
			load_baudrate);
		udelay(50000);
		flush();
		gd->baudrate = load_baudrate;
		serial_setbrg();
		udelay(50000);
		for (;;) {
			if (getchar() == '\r')
				break;
		}
	}
#else	/* ! CONFIG_SYS_LOADS_BAUD_CHANGE */
	if (argc == 2) {
		offset = simple_strtol(argv[1], NULL, 16);
	}
#endif	/* CONFIG_SYS_LOADS_BAUD_CHANGE */

	printf("## Ready for S-Record download ...\n");

	addr = load_serial(offset);

	/*
	 * Gather any trailing characters (for instance, the ^D which
	 * is sent by 'cu' after sending a file), and give the
	 * box some time (100 * 1 ms)
	 */
	for (i=0; i<100; ++i) {
		if (tstc()) {
			getchar();
		}
		udelay(1000);
	}

	if (addr == ~0) {
		printf("## S-Record download aborted\n");
		rcode = 1;
	} else {
		printf("## Start Addr      = 0x%08lX\n", addr);
		image_load_addr = addr;
	}

#ifdef	CONFIG_SYS_LOADS_BAUD_CHANGE
	if (load_baudrate != current_baudrate) {
		printf("## Switch baudrate to %d bps and press ESC ...\n",
			current_baudrate);
		udelay(50000);
		flush();
		gd->baudrate = current_baudrate;
		serial_setbrg();
		udelay(50000);
		for (;;) {
			if (getchar() == 0x1B) /* ESC */
				break;
		}
	}
#endif
	return rcode;
}

static ulong load_serial(long offset)
{
	char	record[SREC_MAXRECLEN + 1];	/* buffer for one S-Record	*/
	char	binbuf[SREC_MAXBINLEN];		/* buffer for binary data	*/
	int	binlen;				/* no. of data bytes in S-Rec.	*/
	int	type;				/* return code for record type	*/
	ulong	addr;				/* load address from S-Record	*/
	ulong	size;				/* number of bytes transferred	*/
	ulong	store_addr;
	ulong	start_addr = ~0;
	ulong	end_addr   =  0;
	int	line_count =  0;
	long ret;

	while (read_record(record, SREC_MAXRECLEN + 1) >= 0) {
		type = srec_decode(record, &binlen, &addr, binbuf);

		if (type < 0) {
			return (~0);		/* Invalid S-Record		*/
		}

		switch (type) {
		case SREC_DATA2:
		case SREC_DATA3:
		case SREC_DATA4:
		    store_addr = addr + offset;
#ifdef CONFIG_MTD_NOR_FLASH
		    if (addr2info(store_addr)) {
			int rc;

			rc = flash_write((char *)binbuf,store_addr,binlen);
			if (rc != 0) {
				flash_perror(rc);
				return (~0);
			}
		    } else
#endif
		    {
			void *dst;
			phys_addr_t dst_addr;

			dst_addr = (phys_addr_t)store_addr;
			ret = lmb_alloc_mem(LMB_MEM_ALLOC_ADDR, 0, &dst_addr,
					    binlen, LMB_NONE);
			if (ret) {
				printf("\nCannot overwrite reserved area (%08lx..%08lx)\n",
					store_addr, store_addr + binlen);
				return ret;
			}
			dst = map_sysmem(dst_addr, binlen);
			memcpy(dst, binbuf, binlen);
			unmap_sysmem(dst);
			lmb_free(dst_addr, binlen, LMB_NONE);
		    }
		    if ((store_addr) < start_addr)
			start_addr = store_addr;
		    if ((store_addr + binlen - 1) > end_addr)
			end_addr = store_addr + binlen - 1;
		    break;
		case SREC_END2:
		case SREC_END3:
		case SREC_END4:
		    udelay(10000);
		    size = end_addr - start_addr + 1;
		    printf("\n"
			    "## First Load Addr = 0x%08lX\n"
			    "## Last  Load Addr = 0x%08lX\n"
			    "## Total Size      = 0x%08lX = %ld Bytes\n",
			    start_addr, end_addr, size, size
		    );
		    flush_cache(start_addr, size);
		    env_set_hex("filesize", size);
		    return (addr);
		case SREC_START:
		    break;
		default:
		    break;
		}
		if (!do_echo) {	/* print a '.' every 100 lines */
			if ((++line_count % 100) == 0)
				putc('.');
		}
	}

	return (~0);			/* Download aborted		*/
}

static int read_record(char *buf, ulong len)
{
	char *p;
	int c;

	--len;	/* always leave room for terminating '\0' byte */

	for (p=buf; p < buf+len; ++p) {
		c = getchar();		/* read character		*/
		if (do_echo)
			putc(c);	/* ... and echo it		*/

		switch (c) {
		case '\r':
		case '\n':
			*p = '\0';
			return (p - buf);
		case '\0':
		case 0x03:			/* ^C - Control C		*/
			return (-1);
		default:
			*p = c;
		}

		/* Check for the console hangup (if any different from serial) */
		if (gd->jt->getc != getchar) {
			if (ctrlc())
				return (-1);
		}
	}

	/* line too long - truncate */
	*p = '\0';
	return (p - buf);
}

#if defined(CONFIG_CMD_SAVES)

int do_save_serial(struct cmd_tbl *cmdtp, int flag, int argc,
		   char *const argv[])
{
	ulong offset = 0;
	ulong size   = 0;
#ifdef	CONFIG_SYS_LOADS_BAUD_CHANGE
	int save_baudrate, current_baudrate;

	save_baudrate = current_baudrate = gd->baudrate;
#endif

	if (argc >= 2) {
		offset = hextoul(argv[1], NULL);
	}
#ifdef	CONFIG_SYS_LOADS_BAUD_CHANGE
	if (argc >= 3) {
		size = hextoul(argv[2], NULL);
	}
	if (argc == 4) {
		save_baudrate = (int)dectoul(argv[3], NULL);

		/* default to current baudrate */
		if (save_baudrate == 0)
			save_baudrate = current_baudrate;
	}
	if (save_baudrate != current_baudrate) {
		printf("## Switch baudrate to %d bps and press ENTER ...\n",
			save_baudrate);
		udelay(50000);
		gd->baudrate = save_baudrate;
		serial_setbrg();
		udelay(50000);
		for (;;) {
			if (getchar() == '\r')
				break;
		}
	}
#else	/* ! CONFIG_SYS_LOADS_BAUD_CHANGE */
	if (argc == 3) {
		size = hextoul(argv[2], NULL);
	}
#endif	/* CONFIG_SYS_LOADS_BAUD_CHANGE */

	printf("## Ready for S-Record upload, press ENTER to proceed ...\n");
	for (;;) {
		if (getchar() == '\r')
			break;
	}
	if (save_serial(offset, size)) {
		printf("## S-Record upload aborted\n");
	} else {
		printf("## S-Record upload complete\n");
	}
#ifdef	CONFIG_SYS_LOADS_BAUD_CHANGE
	if (save_baudrate != current_baudrate) {
		printf("## Switch baudrate to %d bps and press ESC ...\n",
			(int)current_baudrate);
		udelay(50000);
		flush();
		gd->baudrate = current_baudrate;
		serial_setbrg();
		udelay(50000);
		for (;;) {
			if (getchar() == 0x1B) /* ESC */
				break;
		}
	}
#endif
	return 0;
}

#define SREC3_START				"S0030000FC\n"
#define SREC3_FORMAT			"S3%02X%08lX%s%02X\n"
#define SREC3_END				"S70500000000FA\n"
#define SREC_BYTES_PER_RECORD	16

static int save_serial(ulong address, ulong count)
{
	int i, c, reclen, checksum, length;
	char *hex = "0123456789ABCDEF";
	char	record[2*SREC_BYTES_PER_RECORD+16];	/* buffer for one S-Record	*/
	char	data[2*SREC_BYTES_PER_RECORD+1];	/* buffer for hex data	*/

	reclen = 0;
	checksum  = 0;

	if(write_record(SREC3_START))			/* write the header */
		return (-1);
	do {
		volatile uchar *src;

		src = map_sysmem(address, count);
		if (count) {				/* collect hex data in the buffer */
			c = src[reclen];		/* get one byte */
			checksum += c;			/* accumulate checksum */
			data[2*reclen]   = hex[(c>>4)&0x0f];
			data[2*reclen+1] = hex[c & 0x0f];
			data[2*reclen+2] = '\0';
			++reclen;
			--count;
		}
		unmap_sysmem((void *)src);
		if(reclen == SREC_BYTES_PER_RECORD || count == 0) {
			/* enough data collected for one record: dump it */
			if(reclen) {	/* build & write a data record: */
				/* address + data + checksum */
				length = 4 + reclen + 1;

				/* accumulate length bytes into checksum */
				for(i = 0; i < 2; i++)
					checksum += (length >> (8*i)) & 0xff;

				/* accumulate address bytes into checksum: */
				for(i = 0; i < 4; i++)
					checksum += (address >> (8*i)) & 0xff;

				/* make proper checksum byte: */
				checksum = ~checksum & 0xff;

				/* output one record: */
				sprintf(record, SREC3_FORMAT, length, address, data, checksum);
				if(write_record(record))
					return (-1);
			}
			address  += reclen;  /* increment address */
			checksum  = 0;
			reclen    = 0;
		}
	}
	while(count);
	if(write_record(SREC3_END))	/* write the final record */
		return (-1);
	return(0);
}

static int write_record(char *buf)
{
	char c;

	while((c = *buf++))
		putc(c);

	/* Check for the console hangup (if any different from serial) */

	if (ctrlc()) {
	    return (-1);
	}
	return (0);
}
# endif

#endif

#if defined(CONFIG_CMD_LOADB)
/*
 * loadb command (load binary) included
 */
#define XON_CHAR        17
#define XOFF_CHAR       19
#define START_CHAR      0x01
#define ETX_CHAR	0x03
#define END_CHAR        0x0D
#define SPACE           0x20
#define K_ESCAPE        0x23
#define SEND_TYPE       'S'
#define DATA_TYPE       'D'
#define ACK_TYPE        'Y'
#define NACK_TYPE       'N'
#define BREAK_TYPE      'B'
#define tochar(x) ((char) (((x) + SPACE) & 0xff))
#define untochar(x) ((int) (((x) - SPACE) & 0xff))

static void set_kerm_bin_mode(unsigned long *);
static int k_recv(void);
static ulong load_serial_bin(ulong offset);

static char his_eol;        /* character he needs at end of packet */
static int  his_pad_count;  /* number of pad chars he needs */
static char his_pad_char;   /* pad chars he needs */
static char his_quote;      /* quote chars he'll use */

static int do_load_serial_bin(struct cmd_tbl *cmdtp, int flag, int argc,
			      char *const argv[])
{
	ulong offset = 0;
	ulong addr;
	int load_baudrate, current_baudrate;
	int rcode = 0;
	char *s;

	/* pre-set offset from CONFIG_SYS_LOAD_ADDR */
	offset = CONFIG_SYS_LOAD_ADDR;

	/* pre-set offset from $loadaddr */
	s = env_get("loadaddr");
	if (s)
		offset = hextoul(s, NULL);

	load_baudrate = current_baudrate = gd->baudrate;

	if (argc >= 2) {
		offset = hextoul(argv[1], NULL);
	}
	if (argc == 3) {
		load_baudrate = (int)dectoul(argv[2], NULL);

		/* default to current baudrate */
		if (load_baudrate == 0)
			load_baudrate = current_baudrate;
	}

	if (load_baudrate != current_baudrate) {
		printf("## Switch baudrate to %d bps and press ENTER ...\n",
			load_baudrate);
		udelay(50000);
		flush();
		gd->baudrate = load_baudrate;
		serial_setbrg();
		udelay(50000);
		for (;;) {
			if (getchar() == '\r')
				break;
		}
	}

	if (strcmp(argv[0],"loady")==0) {
		printf("## Ready for binary (ymodem) download "
			"to 0x%08lX at %d bps...\n",
			offset,
			load_baudrate);

		addr = load_serial_ymodem(offset, xyzModem_ymodem);

		if (addr == ~0) {
			image_load_addr = 0;
			printf("## Binary (ymodem) download aborted\n");
			rcode = 1;
		} else {
			printf("## Start Addr      = 0x%08lX\n", addr);
			image_load_addr = addr;
		}
	} else if (strcmp(argv[0],"loadx")==0) {
		printf("## Ready for binary (xmodem) download "
			"to 0x%08lX at %d bps...\n",
			offset,
			load_baudrate);

		addr = load_serial_ymodem(offset, xyzModem_xmodem);

		if (addr == ~0) {
			image_load_addr = 0;
			printf("## Binary (xmodem) download aborted\n");
			rcode = 1;
		} else {
			printf("## Start Addr      = 0x%08lX\n", addr);
			image_load_addr = addr;
		}
	} else {

		printf("## Ready for binary (kermit) download "
			"to 0x%08lX at %d bps...\n",
			offset,
			load_baudrate);
		addr = load_serial_bin(offset);

		if (addr == ~0) {
			image_load_addr = 0;
			printf("## Binary (kermit) download aborted\n");
			rcode = 1;
		} else {
			printf("## Start Addr      = 0x%08lX\n", addr);
			image_load_addr = addr;
		}
	}
	if (load_baudrate != current_baudrate) {
		printf("## Switch baudrate to %d bps and press ESC ...\n",
			current_baudrate);
		udelay(50000);
		flush();
		gd->baudrate = current_baudrate;
		serial_setbrg();
		udelay(50000);
		for (;;) {
			if (getchar() == 0x1B) /* ESC */
				break;
		}
	}

	return rcode;
}

static ulong load_serial_bin(ulong offset)
{
	int size, i;

	set_kerm_bin_mode((ulong *) offset);
	size = k_recv();

	/*
	 * Gather any trailing characters (for instance, the ^D which
	 * is sent by 'cu' after sending a file), and give the
	 * box some time (100 * 1 ms)
	 */
	for (i=0; i<100; ++i) {
		if (tstc()) {
			getchar();
		}
		udelay(1000);
	}

	if (size == 0)
		return ~0; /* Download aborted */

	flush_cache(offset, size);

	printf("## Total Size      = 0x%08x = %d Bytes\n", size, size);
	env_set_hex("filesize", size);

	return offset;
}

static void send_pad(void)
{
	int count = his_pad_count;

	while (count-- > 0)
		putc(his_pad_char);
}

/* converts escaped kermit char to binary char */
static char ktrans(char in)
{
	if ((in & 0x60) == 0x40) {
		return (char) (in & ~0x40);
	} else if ((in & 0x7f) == 0x3f) {
		return (char) (in | 0x40);
	} else
		return in;
}

static int chk1(char *buffer)
{
	int total = 0;

	while (*buffer) {
		total += *buffer++;
	}
	return (int) ((total + ((total >> 6) & 0x03)) & 0x3f);
}

static void s1_sendpacket(char *packet)
{
	send_pad();
	while (*packet) {
		putc(*packet++);
	}
}

static char a_b[24];
static void send_ack(int n)
{
	a_b[0] = START_CHAR;
	a_b[1] = tochar(3);
	a_b[2] = tochar(n);
	a_b[3] = ACK_TYPE;
	a_b[4] = '\0';
	a_b[4] = tochar(chk1(&a_b[1]));
	a_b[5] = his_eol;
	a_b[6] = '\0';
	s1_sendpacket(a_b);
}

static void send_nack(int n)
{
	a_b[0] = START_CHAR;
	a_b[1] = tochar(3);
	a_b[2] = tochar(n);
	a_b[3] = NACK_TYPE;
	a_b[4] = '\0';
	a_b[4] = tochar(chk1(&a_b[1]));
	a_b[5] = his_eol;
	a_b[6] = '\0';
	s1_sendpacket(a_b);
}

static void (*os_data_init)(void);
static void (*os_data_char)(char new_char);
static int os_data_state, os_data_state_saved;
static char *os_data_addr, *os_data_addr_saved;
static char *bin_start_address;

static void bin_data_init(void)
{
	os_data_state = 0;
	os_data_addr = bin_start_address;
}

static void os_data_save(void)
{
	os_data_state_saved = os_data_state;
	os_data_addr_saved = os_data_addr;
}

static void os_data_restore(void)
{
	os_data_state = os_data_state_saved;
	os_data_addr = os_data_addr_saved;
}

static void bin_data_char(char new_char)
{
	switch (os_data_state) {
	case 0:					/* data */
		*os_data_addr++ = new_char;
		break;
	}
}

static void set_kerm_bin_mode(unsigned long *addr)
{
	bin_start_address = (char *) addr;
	os_data_init = bin_data_init;
	os_data_char = bin_data_char;
}

/* k_data_* simply handles the kermit escape translations */
static int k_data_escape, k_data_escape_saved;
static void k_data_init(void)
{
	k_data_escape = 0;
	os_data_init();
}

static void k_data_save(void)
{
	k_data_escape_saved = k_data_escape;
	os_data_save();
}

static void k_data_restore(void)
{
	k_data_escape = k_data_escape_saved;
	os_data_restore();
}

static void k_data_char(char new_char)
{
	if (k_data_escape) {
		/* last char was escape - translate this character */
		os_data_char(ktrans(new_char));
		k_data_escape = 0;
	} else {
		if (new_char == his_quote) {
			/* this char is escape - remember */
			k_data_escape = 1;
		} else {
			/* otherwise send this char as-is */
			os_data_char(new_char);
		}
	}
}

#define SEND_DATA_SIZE  20
static char send_parms[SEND_DATA_SIZE];
static char *send_ptr;

/* handle_send_packet interprits the protocol info and builds and
   sends an appropriate ack for what we can do */
static void handle_send_packet(int n)
{
	int length = 3;
	int bytes;

	/* initialize some protocol parameters */
	his_eol = END_CHAR;		/* default end of line character */
	his_pad_count = 0;
	his_pad_char = '\0';
	his_quote = K_ESCAPE;

	/* ignore last character if it filled the buffer */
	if (send_ptr == &send_parms[SEND_DATA_SIZE - 1])
		--send_ptr;
	bytes = send_ptr - send_parms;	/* how many bytes we'll process */
	do {
		if (bytes-- <= 0)
			break;
		/* handle MAXL - max length */
		/* ignore what he says - most I'll take (here) is 94 */
		a_b[++length] = tochar(94);
		if (bytes-- <= 0)
			break;
		/* handle TIME - time you should wait for my packets */
		/* ignore what he says - don't wait for my ack longer than 1 second */
		a_b[++length] = tochar(1);
		if (bytes-- <= 0)
			break;
		/* handle NPAD - number of pad chars I need */
		/* remember what he says - I need none */
		his_pad_count = untochar(send_parms[2]);
		a_b[++length] = tochar(0);
		if (bytes-- <= 0)
			break;
		/* handle PADC - pad chars I need */
		/* remember what he says - I need none */
		his_pad_char = ktrans(send_parms[3]);
		a_b[++length] = 0x40;	/* He should ignore this */
		if (bytes-- <= 0)
			break;
		/* handle EOL - end of line he needs */
		/* remember what he says - I need CR */
		his_eol = untochar(send_parms[4]);
		a_b[++length] = tochar(END_CHAR);
		if (bytes-- <= 0)
			break;
		/* handle QCTL - quote control char he'll use */
		/* remember what he says - I'll use '#' */
		his_quote = send_parms[5];
		a_b[++length] = '#';
		if (bytes-- <= 0)
			break;
		/* handle QBIN - 8-th bit prefixing */
		/* ignore what he says - I refuse */
		a_b[++length] = 'N';
		if (bytes-- <= 0)
			break;
		/* handle CHKT - the clock check type */
		/* ignore what he says - I do type 1 (for now) */
		a_b[++length] = '1';
		if (bytes-- <= 0)
			break;
		/* handle REPT - the repeat prefix */
		/* ignore what he says - I refuse (for now) */
		a_b[++length] = 'N';
		if (bytes-- <= 0)
			break;
		/* handle CAPAS - the capabilities mask */
		/* ignore what he says - I only do long packets - I don't do windows */
		a_b[++length] = tochar(2);	/* only long packets */
		a_b[++length] = tochar(0);	/* no windows */
		a_b[++length] = tochar(94);	/* large packet msb */
		a_b[++length] = tochar(94);	/* large packet lsb */
	} while (0);

	a_b[0] = START_CHAR;
	a_b[1] = tochar(length);
	a_b[2] = tochar(n);
	a_b[3] = ACK_TYPE;
	a_b[++length] = '\0';
	a_b[length] = tochar(chk1(&a_b[1]));
	a_b[++length] = his_eol;
	a_b[++length] = '\0';
	s1_sendpacket(a_b);
}

/* k_recv receives a OS Open image file over kermit line */
static int k_recv(void)
{
	int new_char;
	char k_state, k_state_saved;
	int sum;
	int done;
	int length;
	int n, last_n;
	int len_lo, len_hi;

	/* initialize some protocol parameters */
	his_eol = END_CHAR;		/* default end of line character */
	his_pad_count = 0;
	his_pad_char = '\0';
	his_quote = K_ESCAPE;

	/* initialize the k_recv and k_data state machine */
	done = 0;
	k_state = 0;
	k_data_init();
	k_state_saved = k_state;
	k_data_save();
	n = 0;				/* just to get rid of a warning */
	last_n = -1;

	/* expect this "type" sequence (but don't check):
	   S: send initiate
	   F: file header
	   D: data (multiple)
	   Z: end of file
	   B: break transmission
	 */

	/* enter main loop */
	while (!done) {
		/* set the send packet pointer to begining of send packet parms */
		send_ptr = send_parms;

		/* With each packet, start summing the bytes starting with the length.
		   Save the current sequence number.
		   Note the type of the packet.
		   If a character less than SPACE (0x20) is received - error.
		 */

#if 0
		/* OLD CODE, Prior to checking sequence numbers */
		/* first have all state machines save current states */
		k_state_saved = k_state;
		k_data_save ();
#endif

		/* get a packet */
		/* wait for the starting character or ^C */
		for (;;) {
			switch (getchar()) {
			case START_CHAR:	/* start packet */
				goto START;
			case ETX_CHAR:		/* ^C waiting for packet */
				return (0);
			default:
				;
			}
		}
START:
		/* get length of packet */
		sum = 0;
		new_char = getchar();
		if ((new_char & 0xE0) == 0)
			goto packet_error;
		sum += new_char & 0xff;
		length = untochar(new_char);
		/* get sequence number */
		new_char = getchar();
		if ((new_char & 0xE0) == 0)
			goto packet_error;
		sum += new_char & 0xff;
		n = untochar(new_char);
		--length;

		/* NEW CODE - check sequence numbers for retried packets */
		/* Note - this new code assumes that the sequence number is correctly
		 * received.  Handling an invalid sequence number adds another layer
		 * of complexity that may not be needed - yet!  At this time, I'm hoping
		 * that I don't need to buffer the incoming data packets and can write
		 * the data into memory in real time.
		 */
		if (n == last_n) {
			/* same sequence number, restore the previous state */
			k_state = k_state_saved;
			k_data_restore();
		} else {
			/* new sequence number, checkpoint the download */
			last_n = n;
			k_state_saved = k_state;
			k_data_save();
		}
		/* END NEW CODE */

		/* get packet type */
		new_char = getchar();
		if ((new_char & 0xE0) == 0)
			goto packet_error;
		sum += new_char & 0xff;
		k_state = new_char;
		--length;
		/* check for extended length */
		if (length == -2) {
			/* (length byte was 0, decremented twice) */
			/* get the two length bytes */
			new_char = getchar();
			if ((new_char & 0xE0) == 0)
				goto packet_error;
			sum += new_char & 0xff;
			len_hi = untochar(new_char);
			new_char = getchar();
			if ((new_char & 0xE0) == 0)
				goto packet_error;
			sum += new_char & 0xff;
			len_lo = untochar(new_char);
			length = len_hi * 95 + len_lo;
			/* check header checksum */
			new_char = getchar();
			if ((new_char & 0xE0) == 0)
				goto packet_error;
			if (new_char != tochar((sum + ((sum >> 6) & 0x03)) & 0x3f))
				goto packet_error;
			sum += new_char & 0xff;
/* --length; */ /* new length includes only data and block check to come */
		}
		/* bring in rest of packet */
		while (length > 1) {
			new_char = getchar();
			if ((new_char & 0xE0) == 0)
				goto packet_error;
			sum += new_char & 0xff;
			--length;
			if (k_state == DATA_TYPE) {
				/* pass on the data if this is a data packet */
				k_data_char (new_char);
			} else if (k_state == SEND_TYPE) {
				/* save send pack in buffer as is */
				*send_ptr++ = new_char;
				/* if too much data, back off the pointer */
				if (send_ptr >= &send_parms[SEND_DATA_SIZE])
					--send_ptr;
			}
		}
		/* get and validate checksum character */
		new_char = getchar();
		if ((new_char & 0xE0) == 0)
			goto packet_error;
		if (new_char != tochar((sum + ((sum >> 6) & 0x03)) & 0x3f))
			goto packet_error;
		/* get END_CHAR */
		new_char = getchar();
		if (new_char != END_CHAR) {
		  packet_error:
			/* restore state machines */
			k_state = k_state_saved;
			k_data_restore();
			/* send a negative acknowledge packet in */
			send_nack(n);
		} else if (k_state == SEND_TYPE) {
			/* crack the protocol parms, build an appropriate ack packet */
			handle_send_packet(n);
		} else {
			/* send simple acknowledge packet in */
			send_ack(n);
			/* quit if end of transmission */
			if (k_state == BREAK_TYPE)
				done = 1;
		}
	}
	return ((ulong) os_data_addr - (ulong) bin_start_address);
}

static int getcxmodem(void) {
	if (tstc())
		return (getchar());
	return -1;
}
static ulong load_serial_ymodem(ulong offset, int mode)
{
	int size;
	int err;
	int res;
	connection_info_t info;
	char ymodemBuf[1024];
	ulong store_addr = ~0;
	ulong addr = 0;

	size = 0;
	info.mode = mode;
	res = xyzModem_stream_open(&info, &err);
	if (!res) {

		err = 0;
		while ((res =
			xyzModem_stream_read(ymodemBuf, 1024, &err)) > 0) {
			store_addr = addr + offset;
			size += res;
			addr += res;
#ifdef CONFIG_MTD_NOR_FLASH
			if (addr2info(store_addr)) {
				int rc;

				rc = flash_write((char *) ymodemBuf,
						  store_addr, res);
				if (rc != 0) {
					xyzModem_stream_terminate(true, &getcxmodem);
					xyzModem_stream_close(&err);
					printf("\n");
					flash_perror(rc);
					return (~0);
				}
			} else
#endif
			{
				memcpy((char *)(store_addr), ymodemBuf,
					res);
			}

		}
		if (err) {
			xyzModem_stream_terminate((err == xyzModem_cancel) ? false : true, &getcxmodem);
			xyzModem_stream_close(&err);
			printf("\n%s\n", xyzModem_error(err));
			return (~0); /* Download aborted */
		}

		if (IS_ENABLED(CONFIG_CMD_BOOTEFI))
			efi_set_bootdev("Uart", "", "",
					map_sysmem(offset, 0), size);

	} else {
		printf("\n%s\n", xyzModem_error(err));
		return (~0); /* Download aborted */
	}

	xyzModem_stream_terminate(false, &getcxmodem);
	xyzModem_stream_close(&err);

	flush_cache(offset, ALIGN(size, ARCH_DMA_MINALIGN));

	printf("## Total Size      = 0x%08x = %d Bytes\n", size, size);
	env_set_hex("filesize", size);

	return offset;
}

#endif

#if defined(CONFIG_CMD_LOADM)
static int do_load_memory_bin(struct cmd_tbl *cmdtp, int flag, int argc,
			      char *const argv[])
{
	ulong	addr, dest, size;
	void	*src, *dst;

	if (argc != 4)
		return CMD_RET_USAGE;

	addr = simple_strtoul(argv[1], NULL, 16);

	dest = simple_strtoul(argv[2], NULL, 16);

	size = simple_strtoul(argv[3], NULL, 16);

	if (!size) {
		printf("loadm: can not load zero bytes\n");
		return 1;
	}

	src = map_sysmem(addr, size);
	dst = map_sysmem(dest, size);

	memcpy(dst, src, size);

	unmap_sysmem(src);
	unmap_sysmem(dst);

	if (IS_ENABLED(CONFIG_CMD_BOOTEFI))
		efi_set_bootdev("Mem", "", "", map_sysmem(dest, 0), size);

	printf("loaded bin to memory: size: %lu\n", size);

	return 0;
}
#endif

/* -------------------------------------------------------------------- */

#if defined(CONFIG_CMD_LOADS)

#ifdef	CONFIG_SYS_LOADS_BAUD_CHANGE
U_BOOT_CMD(
	loads, 3, 0,	do_load_serial,
	"load S-Record file over serial line",
	"[ off ] [ baud ]\n"
	"    - load S-Record file over serial line"
	" with offset 'off' and baudrate 'baud'"
);

#else	/* ! CONFIG_SYS_LOADS_BAUD_CHANGE */
U_BOOT_CMD(
	loads, 2, 0,	do_load_serial,
	"load S-Record file over serial line",
	"[ off ]\n"
	"    - load S-Record file over serial line with offset 'off'"
);
#endif	/* CONFIG_SYS_LOADS_BAUD_CHANGE */

/*
 * SAVES always requires LOADS support, but not vice versa
 */

#if defined(CONFIG_CMD_SAVES)
#ifdef	CONFIG_SYS_LOADS_BAUD_CHANGE
U_BOOT_CMD(
	saves, 4, 0,	do_save_serial,
	"save S-Record file over serial line",
	"[ off ] [size] [ baud ]\n"
	"    - save S-Record file over serial line"
	" with offset 'off', size 'size' and baudrate 'baud'"
);
#else	/* ! CONFIG_SYS_LOADS_BAUD_CHANGE */
U_BOOT_CMD(
	saves, 3, 0,	do_save_serial,
	"save S-Record file over serial line",
	"[ off ] [size]\n"
	"    - save S-Record file over serial line with offset 'off' and size 'size'"
);
#endif	/* CONFIG_SYS_LOADS_BAUD_CHANGE */
#endif	/* CONFIG_CMD_SAVES */
#endif	/* CONFIG_CMD_LOADS */

#if defined(CONFIG_CMD_LOADB)
U_BOOT_CMD(
	loadb, 3, 0,	do_load_serial_bin,
	"load binary file over serial line (kermit mode)",
	"[ addr [ baud ] ]\n"
	"    - load binary file over serial line"
	" at address 'addr' with baudrate 'baud'"
);

U_BOOT_CMD(
	loadx, 3, 0,	do_load_serial_bin,
	"load binary file over serial line (xmodem mode)",
	"[ addr [ baud ] ]\n"
	"    - load binary file over serial line"
	" at address 'addr' with baudrate 'baud'"
);

U_BOOT_CMD(
	loady, 3, 0,	do_load_serial_bin,
	"load binary file over serial line (ymodem mode)",
	"[ addr [ baud ] ]\n"
	"    - load binary file over serial line"
	" at address 'addr' with baudrate 'baud'"
);

#endif	/* CONFIG_CMD_LOADB */

#if defined(CONFIG_CMD_LOADM)
U_BOOT_CMD(
	loadm, 4, 0,	do_load_memory_bin,
	"load binary blob from source address to destination address",
	"[src_addr] [dst_addr] [size]\n"
	"     - load a binary blob from one memory location to other"
	" from src_addr to dst_addr by size bytes"
);
#endif /* CONFIG_CMD_LOADM */
