* Patch by Scott McNutt, 21 Oct 2004:

  Add support for Nios-II EPCS Controller core.

* Patch by Scott McNutt, 20 Oct 2004:
  Nios-II cleanups:
  - Add sysid command (Nios-II only).
  - Locate default exception trampoline at proper offset.
  - Implement I/O routines (readb, writeb, etc)
  - Implement do_bootm_linux

5 files changed, 788 insertions, 27 deletions

diff --git a/cpu/nios2/Makefile b/cpu/nios2/Makefile
index 76b324a..11fda50 100644
--- a/cpu/nios2/Makefile
+++ b/cpu/nios2/Makefile
@@ -27,7 +27,7 @@ LIB	= lib$(CPU).a
 
 START	= start.o
 AOBJS	= exceptions.o
-OBJS	= cpu.o interrupts.o serial.o traps.o
+OBJS	= cpu.o interrupts.o serial.o sysid.o traps.o epcs.o
 
 all:	.depend $(START) $(LIB)
 
diff --git a/cpu/nios2/cpu.c b/cpu/nios2/cpu.c
index c9db127..f4217a8 100644
--- a/cpu/nios2/cpu.c
+++ b/cpu/nios2/cpu.c
@@ -26,19 +26,7 @@
 #include <nios2-io.h>
 
 #if defined (CFG_NIOS_SYSID_BASE)
-#include <linux/time.h>
-static void check_sysid (void)
-{
-	struct nios_sysid_t *sysid =
-		(struct nios_sysid_t *)CACHE_BYPASS(CFG_NIOS_SYSID_BASE);
-	struct tm t;
-	char asc[32];
-
-	localtime_r ((time_t *)&sysid->timestamp, &t);
-	asctime_r (&t, asc);
-	printf ("SYSID : %08x, %s", sysid->id, asc);
-
-}
+extern void display_sysid (void);
 #endif /* CFG_NIOS_SYSID_BASE */
 
 int checkcpu (void)
@@ -47,7 +35,7 @@ int checkcpu (void)
 #if !defined(CFG_NIOS_SYSID_BASE)
 	printf ("SYSID : <unknown>\n");
 #else
-	check_sysid ();
+	display_sysid ();
 #endif
 	return (0);
 }
diff --git a/cpu/nios2/epcs.c b/cpu/nios2/epcs.c
new file mode 100644
index 0000000..a8851e9
--- /dev/null
+++ b/cpu/nios2/epcs.c
@@ -0,0 +1,711 @@
+/*
+ * (C) Copyright 2004, Psyent Corporation <www.psyent.com>
+ * Scott McNutt <smcnutt@psyent.com>
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+
+#if defined(CFG_NIOS_EPCSBASE)
+#include <command.h>
+#include <nios2.h>
+#include <nios2-io.h>
+#include <nios2-epcs.h>
+
+
+/*-----------------------------------------------------------------------*/
+#define SHORT_HELP\
+	"epcs    - read/write Cyclone EPCS configuration device.\n"
+
+#define LONG_HELP\
+	"\n"\
+	"epcs erase start [end]\n"\
+	"    - erase sector start or sectors start through end.\n"\
+	"epcs info\n"\
+	"    - display EPCS device information.\n"\
+	"epcs protect on | off\n"\
+	"    - turn device protection on or off.\n"\
+	"epcs read addr offset count\n"\
+	"    - read count bytes from offset to addr.\n"\
+	"epcs write addr offset count\n"\
+	"    - write count bytes to offset from addr.\n"\
+	"epcs verify addr offset count\n"\
+	"    - verify count bytes at offset from addr.\n"
+
+
+/*-----------------------------------------------------------------------*/
+/* Operation codes for serial configuration devices
+ */
+#define EPCS_WRITE_ENA		0x06	/* Write enable */
+#define EPCS_WRITE_DIS		0x04	/* Write disable */
+#define EPCS_READ_STAT		0x05	/* Read status */
+#define EPCS_READ_BYTES		0x03	/* Read bytes */
+#define EPCS_READ_ID		0xab	/* Read silicon id */
+#define EPCS_WRITE_STAT		0x01	/* Write status */
+#define EPCS_WRITE_BYTES	0x02	/* Write bytes */
+#define EPCS_ERASE_BULK		0xc7	/* Erase entire device */
+#define EPCS_ERASE_SECT		0xd8	/* Erase sector */
+
+/* Device status register bits
+ */
+#define EPCS_STATUS_WIP		(1<<0)	/* Write in progress */
+#define EPCS_STATUS_WEL		(1<<1)	/* Write enable latch */
+
+/* Misc
+ */
+#define EPCS_TIMEOUT		100	/* 100 msec timeout */
+
+static nios_spi_t *epcs =
+	(nios_spi_t *)CACHE_BYPASS(CFG_NIOS_EPCSBASE);
+
+/***********************************************************************
+ * Device access
+ ***********************************************************************/
+static int epcs_cs (int assert)
+{
+	ulong start;
+
+	if (assert) {
+		epcs->control |= NIOS_SPI_SSO;
+	} else {
+		/* Let all bits shift out */
+		start = get_timer (0);
+		while ((epcs->status & NIOS_SPI_TMT) == 0)
+			if (get_timer (start) > EPCS_TIMEOUT)
+				return (-1);
+		epcs->control &= ~NIOS_SPI_SSO;
+	}
+	return (0);
+}
+
+static int epcs_tx (unsigned char c)
+{
+	ulong start;
+
+	start = get_timer (0);
+	while ((epcs->status & NIOS_SPI_TRDY) == 0)
+		if (get_timer (start) > EPCS_TIMEOUT)
+			return (-1);
+	epcs->txdata = c;
+	return (0);
+}
+
+static int epcs_rx (void)
+{
+	ulong start;
+
+	start = get_timer (0);
+	while ((epcs->status & NIOS_SPI_RRDY) == 0)
+		if (get_timer (start) > EPCS_TIMEOUT)
+			return (-1);
+	return (epcs->rxdata);
+}
+
+static unsigned char bitrev[] = {
+	0x00, 0x08, 0x04, 0x0c, 0x02, 0x0a, 0x06, 0x0e,
+	0x01, 0x09, 0x05, 0x0d, 0x03, 0x0b, 0x07, 0x0f
+};
+
+static unsigned char epcs_bitrev (unsigned char c)
+{
+	unsigned char val;
+
+	val  = bitrev[c>>4];
+	val |= bitrev[c & 0x0f]<<4;
+	return (val);
+}
+
+static void epcs_rcv (unsigned char *dst, int len)
+{
+	while (len--) {
+		epcs_tx (0);
+		*dst++ = epcs_rx ();
+	}
+}
+
+static void epcs_rrcv (unsigned char *dst, int len)
+{
+	while (len--) {
+		epcs_tx (0);
+		*dst++ = epcs_bitrev (epcs_rx ());
+	}
+}
+
+static void epcs_snd (unsigned char *src, int len)
+{
+	while (len--) {
+		epcs_tx (*src++);
+		epcs_rx ();
+	}
+}
+
+static void epcs_rsnd (unsigned char *src, int len)
+{
+	while (len--) {
+		epcs_tx (epcs_bitrev (*src++));
+		epcs_rx ();
+	}
+}
+
+static void epcs_wr_enable (void)
+{
+	epcs_cs (1);
+	epcs_tx (EPCS_WRITE_ENA);
+	epcs_rx ();
+	epcs_cs (0);
+}
+
+static unsigned char epcs_status_rd (void)
+{
+	unsigned char status;
+
+	epcs_cs (1);
+	epcs_tx (EPCS_READ_STAT);
+	epcs_rx ();
+	epcs_tx (0);
+	status = epcs_rx ();
+	epcs_cs (0);
+	return (status);
+}
+
+static void epcs_status_wr (unsigned char status)
+{
+	epcs_wr_enable ();
+	epcs_cs (1);
+	epcs_tx (EPCS_WRITE_STAT);
+	epcs_rx ();
+	epcs_tx (status);
+	epcs_rx ();
+	epcs_cs (0);
+	return;
+}
+
+/***********************************************************************
+ * Device information
+ ***********************************************************************/
+
+static struct epcs_devinfo_t devinfo[] = {
+	{ "EPCS1 ", 0x10, 17, 4, 15, 8, 0x0c },
+	{ "EPCS4 ", 0x12, 19, 8, 16, 8, 0x1c },
+	{ 0, 0, 0, 0, 0, 0 }
+};
+
+epcs_devinfo_t *epcs_dev_find (void)
+{
+	unsigned char buf[4];
+	unsigned char id;
+	int i;
+	struct epcs_devinfo_t *dev = NULL;
+
+	/* Read silicon id requires 3 "dummy bytes" before it's put
+	 * on the wire.
+	 */
+	buf[0] = EPCS_READ_ID;
+	buf[1] = 0;
+	buf[2] = 0;
+	buf[3] = 0;
+
+	epcs_cs (1);
+	epcs_snd (buf,4);
+	epcs_rcv (buf,1);
+	if (epcs_cs (0) == -1)
+		return (NULL);
+	id = buf[0];
+
+	/* Find the info struct */
+	i = 0;
+	while (devinfo[i].name) {
+		if (id == devinfo[i].id) {
+			dev = &devinfo[i];
+			break;
+		}
+		i++;
+	}
+
+	return (dev);
+}
+
+/***********************************************************************
+ * Misc Utilities
+ ***********************************************************************/
+int epcs_cfgsz (void)
+{
+	int sz = 0;
+	unsigned char buf[128];
+	unsigned char *p;
+	struct epcs_devinfo_t *dev = epcs_dev_find ();
+
+	if (!dev)
+		return (-1);
+
+	/* Read in the first 128 bytes of the device */
+	buf[0] = EPCS_READ_BYTES;
+	buf[1] = 0;
+	buf[2] = 0;
+	buf[3] = 0;
+
+	epcs_cs (1);
+	epcs_snd (buf,4);
+	epcs_rrcv (buf, sizeof(buf));
+	epcs_cs (0);
+
+	/* Search for the starting 0x6a which is followed by the
+	 * 4-byte 'register' and 4-byte bit-count.
+	 */
+	p = buf;
+	while (p < buf + sizeof(buf)-8) {
+		if ( *p == 0x6a ) {
+			/* Point to bit count and extract */
+			p += 5;
+			sz = *p++;
+			sz |= *p++ << 8;
+			sz |= *p++ << 16;
+			sz |= *p++ << 24;
+			/* Convert to byte count */
+			sz += 7;
+			sz >>= 3;
+		} else if (*p == 0xff) {
+			/* 0xff is ok ... just skip */
+			p++;
+			continue;
+		} else {
+			/* Not 0xff or 0x6a ... something's not
+			 * right ... report 'unknown' (sz=0).
+			 */
+			break;
+		}
+	}
+	return (sz);
+}
+
+int epcs_erase (unsigned start, unsigned end)
+{
+	unsigned off, sectsz;
+	unsigned char buf[4];
+	struct epcs_devinfo_t *dev = epcs_dev_find ();
+
+	if (!dev || (start>end))
+		return (-1);
+
+	/* Erase the requested sectors. An address is required
+	 * that lies within the requested sector -- we'll just
+	 * use the first address in the sector.
+	 */
+	printf ("epcs erasing sector %d ", start);
+	if (start != end)
+		printf ("to %d ", end);
+	sectsz = (1 << dev->sz_sect);
+	while (start <= end) {
+		off = start * sectsz;
+		start++;
+
+		buf[0] = EPCS_ERASE_SECT;
+		buf[1] = off >> 16;
+		buf[2] = off >> 8;
+		buf[3] = off;
+
+		epcs_wr_enable ();
+		epcs_cs (1);
+		epcs_snd (buf,4);
+		epcs_cs (0);
+
+		printf ("."); /* Some user feedback */
+
+		/* Wait for erase to complete */
+		while (epcs_status_rd() & EPCS_STATUS_WIP)
+			;
+	}
+	printf (" done.\n");
+	return (0);
+}
+
+int epcs_read (ulong addr, ulong off, ulong cnt)
+{
+	unsigned char buf[4];
+	struct epcs_devinfo_t *dev = epcs_dev_find ();
+
+	if (!dev)
+		return (-1);
+
+	buf[0] = EPCS_READ_BYTES;
+	buf[1] = off >> 16;
+	buf[2] = off >> 8;
+	buf[3] = off;
+
+	epcs_cs (1);
+	epcs_snd (buf,4);
+	epcs_rrcv ((unsigned char *)addr, cnt);
+	epcs_cs (0);
+
+	return (0);
+}
+
+int epcs_write (ulong addr, ulong off, ulong cnt)
+{
+	ulong wrcnt;
+	unsigned pgsz;
+	unsigned char buf[4];
+	struct epcs_devinfo_t *dev = epcs_dev_find ();
+
+	if (!dev)
+		return (-1);
+
+	pgsz = (1<<dev->sz_page);
+	while (cnt) {
+		if (off % pgsz)
+			wrcnt = pgsz - (off % pgsz);
+		else
+			wrcnt = pgsz;
+		wrcnt = (wrcnt > cnt) ? cnt : wrcnt;
+
+		buf[0] = EPCS_WRITE_BYTES;
+		buf[1] = off >> 16;
+		buf[2] = off >> 8;
+		buf[3] = off;
+
+		epcs_wr_enable ();
+		epcs_cs (1);
+		epcs_snd (buf,4);
+		epcs_rsnd ((unsigned char *)addr, wrcnt);
+		epcs_cs (0);
+
+		/* Wait for write to complete */
+		while (epcs_status_rd() & EPCS_STATUS_WIP)
+			;
+
+		cnt -= wrcnt;
+		off += wrcnt;
+		addr += wrcnt;
+	}
+
+	return (0);
+}
+
+int epcs_verify (ulong addr, ulong off, ulong cnt, ulong *err)
+{
+	ulong rdcnt;
+	unsigned char buf[256];
+	unsigned char *start,*end;
+	int i;
+
+	start = end = (unsigned char *)addr;
+	while (cnt) {
+		rdcnt = (cnt>sizeof(buf)) ? sizeof(buf) : cnt;
+		epcs_read ((ulong)buf, off, rdcnt);
+		for (i=0; i<rdcnt; i++) {
+			if (*end != buf[i]) {
+				*err = end - start;
+				return(-1);
+			}
+			end++;
+		}
+		cnt -= rdcnt;
+		off += rdcnt;
+	}
+	return (0);
+}
+
+static int epcs_sect_erased (int sect, unsigned *offset,
+		struct epcs_devinfo_t *dev)
+{
+	unsigned char buf[128];
+	unsigned off, end;
+	unsigned sectsz;
+	int i;
+
+	sectsz = (1 << dev->sz_sect);
+	off = sectsz * sect;
+	end = off + sectsz;
+
+	while (off < end) {
+		epcs_read ((ulong)buf, off, sizeof(buf));
+		for (i=0; i < sizeof(buf); i++) {
+			if (buf[i] != 0xff) {
+				*offset = off + i;
+				return (0);
+			}
+		}
+		off += sizeof(buf);
+	}
+	return (1);
+}
+
+
+/***********************************************************************
+ * Commands
+ ***********************************************************************/
+static
+void do_epcs_info (struct epcs_devinfo_t *dev, int argc, char *argv[])
+{
+	int i;
+	unsigned char stat;
+	unsigned tmp;
+	int erased;
+
+	/* Basic device info */
+	printf ("%s: %d kbytes (%d sectors x %d kbytes,"
+		" %d bytes/page)\n",
+		dev->name, 1 << (dev->size-10),
+		dev->num_sects, 1 << (dev->sz_sect-10),
+		1 << dev->sz_page );
+
+	/* Status -- for now protection is all-or-nothing */
+	stat = epcs_status_rd();
+	printf ("status: 0x%02x (WIP:%d, WEL:%d, PROT:%s)\n",
+		stat,
+		(stat & EPCS_STATUS_WIP) ? 1 : 0,
+	        (stat & EPCS_STATUS_WEL) ? 1 : 0,
+		(stat & dev->prot_mask) ? "on" : "off" );
+
+	/* Configuration  */
+	tmp = epcs_cfgsz ();
+	if (tmp) {
+		printf ("config: 0x%06x (%d) bytes\n", tmp, tmp );
+	} else {
+		printf ("config: unknown\n" );
+	}
+
+	/* Sector info */
+	for (i=0; i<dev->num_sects; i++) {
+		erased = epcs_sect_erased (i, &tmp, dev);
+		printf ("     %d: %06x ",
+			i, i*(1<<dev->sz_sect) );
+		if (erased)
+			printf ("erased\n");
+		else
+			printf ("data @ 0x%06x\n", tmp);
+	}
+
+	return;
+}
+
+static
+void do_epcs_erase (struct epcs_devinfo_t *dev, int argc, char *argv[])
+{
+	unsigned start,end;
+
+	if ((argc < 3) || (argc > 4)) {
+		printf ("USAGE: epcs erase sect [end]\n");
+		return;
+	}
+	if ((epcs_status_rd() & dev->prot_mask) != 0) {
+		printf ( "epcs: device protected.\n");
+		return;
+	}
+
+	start = simple_strtoul (argv[2], NULL, 10);
+	if (argc > 3)
+		end = simple_strtoul (argv[3], NULL, 10);
+	else
+		end = start;
+	if ((start >= dev->num_sects) || (start > end)) {
+		printf ("epcs: invalid sector range: [%d:%d]\n",
+			start, end );
+		return;
+	}
+
+	epcs_erase (start, end);
+
+	return;
+}
+
+static
+void do_epcs_protect (struct epcs_devinfo_t *dev, int argc, char *argv[])
+{
+	unsigned char stat;
+
+	/* For now protection is all-or-nothing to keep things
+	 * simple. The protection bits don't map in a linear
+	 * fashion ... and we would rather protect the bottom
+	 * of the device since it contains the config data and
+	 * leave the top unprotected for app use. But unfortunately
+	 * protection works from top-to-bottom so it does
+	 * really help very much from a software app point-of-view.
+	 */
+	if (argc < 3) {
+		printf ("USAGE: epcs protect on | off\n");
+		return;
+	}
+	if (!dev)
+		return;
+
+	/* Protection on/off is just a matter of setting/clearing
+	 * all protection bits in the status register.
+	 */
+	stat = epcs_status_rd ();
+	if (strcmp ("on", argv[2]) == 0) {
+		stat |= dev->prot_mask;
+	} else if (strcmp ("off", argv[2]) == 0 ) {
+		stat &= ~dev->prot_mask;
+	} else {
+		printf ("epcs: unknown protection: %s\n", argv[2]);
+		return;
+	}
+	epcs_status_wr (stat);
+	return;
+}
+
+static
+void do_epcs_read (struct epcs_devinfo_t *dev, int argc, char *argv[])
+{
+	ulong addr,off,cnt;
+	ulong sz;
+
+	if (argc < 5) {
+		printf ("USAGE: epcs read addr offset count\n");
+		return;
+	}
+
+	sz = 1 << dev->size;
+	addr = simple_strtoul (argv[2], NULL, 16);
+	off  = simple_strtoul (argv[3], NULL, 16);
+	cnt  = simple_strtoul (argv[4], NULL, 16);
+	if (off > sz) {
+		printf ("offset is greater than device size"
+			"... aborting.\n");
+		return;
+	}
+	if ((off + cnt) > sz) {
+		printf ("request exceeds device size"
+			"... truncating.\n");
+		cnt = sz - off;
+	}
+	printf ("epcs: read %08lx <- %06lx (0x%lx bytes)\n",
+			addr, off, cnt);
+	epcs_read (addr, off, cnt);
+
+	return;
+}
+
+static
+void do_epcs_write (struct epcs_devinfo_t *dev, int argc, char *argv[])
+{
+	ulong addr,off,cnt;
+	ulong sz;
+	ulong err;
+
+	if (argc < 5) {
+		printf ("USAGE: epcs write addr offset count\n");
+		return;
+	}
+	if ((epcs_status_rd() & dev->prot_mask) != 0) {
+		printf ( "epcs: device protected.\n");
+		return;
+	}
+
+	sz = 1 << dev->size;
+	addr = simple_strtoul (argv[2], NULL, 16);
+	off  = simple_strtoul (argv[3], NULL, 16);
+	cnt  = simple_strtoul (argv[4], NULL, 16);
+	if (off > sz) {
+		printf ("offset is greater than device size"
+			"... aborting.\n");
+		return;
+	}
+	if ((off + cnt) > sz) {
+		printf ("request exceeds device size"
+			"... truncating.\n");
+		cnt = sz - off;
+	}
+	printf ("epcs: write %08lx -> %06lx (0x%lx bytes)\n",
+			addr, off, cnt);
+	epcs_write (addr, off, cnt);
+	if (epcs_verify (addr, off, cnt, &err) != 0)
+		printf ("epcs: write error at offset %06lx\n", err);
+
+	return;
+}
+
+static
+void do_epcs_verify (struct epcs_devinfo_t *dev, int argc, char *argv[])
+{
+	ulong addr,off,cnt;
+	ulong sz;
+	ulong err;
+
+	if (argc < 5) {
+		printf ("USAGE: epcs verify addr offset count\n");
+		return;
+	}
+
+	sz = 1 << dev->size;
+	addr = simple_strtoul (argv[2], NULL, 16);
+	off  = simple_strtoul (argv[3], NULL, 16);
+	cnt  = simple_strtoul (argv[4], NULL, 16);
+	if (off > sz) {
+		printf ("offset is greater than device size"
+			"... aborting.\n");
+		return;
+	}
+	if ((off + cnt) > sz) {
+		printf ("request exceeds device size"
+			"... truncating.\n");
+		cnt = sz - off;
+	}
+	printf ("epcs: verify %08lx -> %06lx (0x%lx bytes)\n",
+			addr, off, cnt);
+	if (epcs_verify (addr, off, cnt, &err) != 0)
+		printf ("epcs: verify error at offset %06lx\n", err);
+
+	return;
+}
+
+/*-----------------------------------------------------------------------*/
+int do_epcs (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+{
+	int len;
+	struct epcs_devinfo_t *dev = epcs_dev_find ();
+
+	if (!dev) {
+		printf ("epcs: device not found.\n");
+		return (-1);
+	}
+
+	if (argc < 2) {
+		do_epcs_info (dev, argc, argv);
+		return (0);
+	}
+
+	len = strlen (argv[1]);
+	if (strncmp ("info", argv[1], len) == 0) {
+		do_epcs_info (dev, argc, argv);
+	} else if (strncmp ("erase", argv[1], len) == 0) {
+		do_epcs_erase (dev, argc, argv);
+	} else if (strncmp ("protect", argv[1], len) == 0) {
+		do_epcs_protect (dev, argc, argv);
+	} else if (strncmp ("read", argv[1], len) == 0) {
+		do_epcs_read (dev, argc, argv);
+	} else if (strncmp ("write", argv[1], len) == 0) {
+		do_epcs_write (dev, argc, argv);
+	} else if (strncmp ("verify", argv[1], len) == 0) {
+		do_epcs_verify (dev, argc, argv);
+	} else {
+		printf ("epcs: unknown operation: %s\n", argv[1]);
+	}
+
+	return (0);
+}
+
+/*-----------------------------------------------------------------------*/
+
+
+U_BOOT_CMD( epcs, 5, 0, do_epcs, SHORT_HELP, LONG_HELP );
+
+#endif /* CONFIG_NIOS_EPCS */
diff --git a/cpu/nios2/start.S b/cpu/nios2/start.S
index 281d42c..4c6e470 100644
--- a/cpu/nios2/start.S
+++ b/cpu/nios2/start.S
@@ -39,14 +39,24 @@ _start:
 	 * just be invalidating the cache a second time. If cache
 	 * is not implemented initi behaves as nop.
 	 */
-	movhi	r4, %hi(CFG_ICACHELINE_SIZE)
-	ori	r4, r4, %lo(CFG_ICACHELINE_SIZE)
+	ori	r4, r0, %lo(CFG_ICACHELINE_SIZE)
 	movhi	r5, %hi(CFG_ICACHE_SIZE)
 	ori	r5, r5, %lo(CFG_ICACHE_SIZE)
 	mov	r6, r0
 0:	initi	r6
 	add	r6, r6, r4
 	bltu	r6, r5, 0b
+	br	_except_end	/* Skip the tramp */
+
+	/* EXCEPTION TRAMPOLINE -- the following gets copied
+	 * to the exception address (below), but is otherwise at the
+	 * default exception vector offset (0x0020).
+	 */
+_except_start:
+	movhi	et, %hi(_exception)
+	ori	et, et, %lo(_exception)
+	jmp	et
+_except_end:
 
 	/* INTERRUPTS -- for now, all interrupts masked and globally
 	 * disabled.
@@ -117,7 +127,9 @@ _cur:	movhi	r5, %hi(_cur - _start)
 _reloc:
 
 	/* COPY EXCEPTION TRAMPOLINE -- copy the tramp to the
-	 * exception address.
+	 * exception address. Define CONFIG_ROM_STUBS to prevent
+	 * the copy (e.g. exception in flash or in other
+	 * softare/firmware component).
 	 */
 #if !defined(CONFIG_ROM_STUBS)
 	movhi	r4, %hi(_except_start)
@@ -126,12 +138,14 @@ _reloc:
 	ori	r5, r5, %lo(_except_end)
 	movhi	r6, %hi(CFG_EXCEPTION_ADDR)
 	ori	r6, r6, %lo(CFG_EXCEPTION_ADDR)
+	beq	r4, r6, 7f	/* Skip if at proper addr */
 
 6:	ldwio	r7, 0(r4)
 	stwio	r7, 0(r6)
 	addi	r4, r4, 4
 	addi	r6, r6, 4
 	bne	r4, r5, 6b
+7:
 #endif
 
 	/* STACK INIT -- zero top two words for call back chain.
@@ -155,15 +169,6 @@ _reloc:
 	 */
 	br	_start
 
-	/* EXCEPTION TRAMPOLINE -- the following gets copied
-	 * to the exception address.
-	 */
-_except_start:
-	movhi	et, %hi(_exception)
-	ori	et, et, %lo(_exception)
-	jmp	et
-_except_end:
-
 
 /*
  * dly_clks -- Nios2 (like Nios1) doesn't have a timebase in
diff --git a/cpu/nios2/sysid.c b/cpu/nios2/sysid.c
new file mode 100644
index 0000000..2b7a569
--- /dev/null
+++ b/cpu/nios2/sysid.c
@@ -0,0 +1,57 @@
+/*
+ * (C) Copyright 2004, Psyent Corporation <www.psyent.com>
+ * Scott McNutt <smcnutt@psyent.com>
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+
+#if defined (CFG_NIOS_SYSID_BASE)
+
+#include <command.h>
+#include <nios2.h>
+#include <nios2-io.h>
+#include <linux/time.h>
+
+void display_sysid (void)
+{
+	struct nios_sysid_t *sysid =
+		(struct nios_sysid_t *)CACHE_BYPASS(CFG_NIOS_SYSID_BASE);
+	struct tm t;
+	char asc[32];
+
+	localtime_r ((time_t *)&sysid->timestamp, &t);
+	asctime_r (&t, asc);
+	printf ("SYSID : %08x, %s", sysid->id, asc);
+
+}
+
+int do_sysid (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+{
+	display_sysid ();
+	return (0);
+}
+
+U_BOOT_CMD(
+	sysid,	1,	1,	do_sysid,
+	"sysid   - display Nios-II system id\n\n",
+	"\n    - display Nios-II system id\n"
+);
+#endif /* CFG_NIOS_SYSID_BASE */