* Patch by Scott McNutt, 04 Oct 2003:
- add support for Altera Nios-32 CPU
- add support for Nios Cyclone Development Kit (DK-1C20)
* Patch by Steven Scholz, 29 Sep 2003:
- A second parameter for bootm overwrites the load address for
"Standalone Application" images.
- bootm sets environment variable "filesize" to the resulting
(uncompressed) data length for "Standalone Application" images
when autostart is set to "no". Now you can do something like
if bootm $fpgadata $some_free_ram ; then
fpga load 0 $some_free_ram $filesize
fi
* Patch by Denis Peter, 25 Sept 2003:
add support for the MIP405 Rev. C board
diff --git a/cpu/nios/start.S b/cpu/nios/start.S
new file mode 100644
index 0000000..7cbd1a7
--- /dev/null
+++ b/cpu/nios/start.S
@@ -0,0 +1,186 @@
+/*
+ * (C) Copyright 2003, 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 <config.h>
+#include <version.h>
+
+#if !defined(CONFIG_IDENT_STRING)
+#define CONFIG_IDENT_STRING ""
+#endif
+
+#define STATUS_INIT 0x8600 /* IE=1, IPRI=2 */
+
+/*************************************************************************
+ * RESTART
+ ************************************************************************/
+
+ .text
+ .global _start
+
+_start:
+ bsr 0f
+ nop
+ .long _start
+
+ /* GERMS -- The "standard-32" configuration GERMS monitor looks
+ * for the string "Nios" at flash_base + 0xc (actually it only
+ * tests for 'N', 'i'). You can leave support for this in place
+ * as it's only a few words.
+ */
+ . = _start + 0x000c
+ .string "Nios"
+
+ .align 4
+0:
+ /*
+ * Early setup -- set cwp = HI_LIMIT, IPRI = 2, IE = 1 to
+ * enable underflow exceptions. Disable cache.
+ * NOTE: %o7 has return addr -- save in %g7 use later.
+ */
+ mov %g7, %o7
+
+ pfx 2 /* WVALID */
+ rdctl %g0
+ lsri %g0, 1
+ pfx %hi(STATUS_INIT)
+ or %g0, %lo(STATUS_INIT)
+ wrctl %g0 /* update status */
+ nop
+
+ /*
+ * STACK
+ */
+ pfx %hi(CFG_INIT_SP)
+ movi %sp, %lo(CFG_INIT_SP)
+ pfx %xhi(CFG_INIT_SP)
+ movhi %sp, %xlo(CFG_INIT_SP)
+ mov %fp, %sp
+
+ pfx %hi(4*16)
+ subi %sp, %lo(4*16) /* Space for reg window mgmt */
+
+ /*
+ * RELOCATE -- %g7 has return addr from bsr at _start.
+ */
+ pfx %hi(__u_boot_cmd_end)
+ movi %g5, %lo(__u_boot_cmd_end)
+ pfx %xhi(__u_boot_cmd_end)
+ movhi %g5, %xlo(__u_boot_cmd_end) /* %g5 <- end address */
+
+ lsli %g7, 1 /* mem = retaddr << 1 */
+ mov %g6, %g7
+ subi %g6, 4 /* %g6 <- src addr */
+ ld %g7, [%g7] /* %g7 <- dst addr */
+
+1: cmp %g7, %g5
+ skps cc_nz
+ br 2f
+ nop /* delay slot */
+
+ ld %g0, [%g6]
+ addi %g6, 4 /* src++ */
+ st [%g7], %g0
+ addi %g7, 4 /* dst++ */
+ br 1b
+ nop /* delay slot */
+2:
+
+ /*
+ * Jump to relocation address
+ */
+ pfx %hi(reloc@h)
+ movi %g0, %lo(reloc@h)
+ pfx %xhi(reloc@h)
+ movhi %g0, %xlo(reloc@h)
+ jmp %g0
+reloc:
+
+ /*
+ * CLEAR BSS
+ */
+ pfx %hi(__bss_end)
+ movi %g5, %lo(__bss_end)
+ pfx %xhi(__bss_end)
+ movhi %g5, %xlo(__bss_end) /* %g5 <- end address */
+ pfx %hi(__bss_start)
+ movi %g7, %lo(__bss_start)
+ pfx %xhi(__bss_start)
+ movhi %g7, %xlo(__bss_start) /* %g7 <- end address */
+
+ movi %g0, 0
+3: cmp %g7, %g5
+ skps cc_nz
+ br 4f
+ nop /* delay slot */
+
+ st [%g7], %g0
+ addi %g7, 4 /* (delay slot) dst++ */
+ br 3b
+ nop /* delay slot */
+4:
+
+ /*
+ * Call board_init -- never returns
+ */
+ pfx %hi(board_init@h)
+ movi %g1, %lo(board_init@h)
+ pfx %xhi(board_init@h)
+ movhi %g1, %xlo(board_init@h)
+ call %g1
+ nop /* Delaly slot */
+ /* NEVER RETURNS */
+
+/*
+ * dly_clks -- Nios doesn't have a time/clk reference for simple
+ * delay loops, so we do our best by counting instruction cycles.
+ * A control register that counts system clock cycles would be
+ * a handy feature -- hint for Altera ;-)
+ */
+ .globl dly_clks
+ /* Each loop is 4 instructions as delay slot is always
+ * executed. Each instruction is approximately 4 clocks
+ * (according to some lame info from Altera). So ...
+ * ... each loop is about 16 clocks.
+ */
+
+dly_clks:
+ lsri %o0, 4 /* cnt/16 */
+
+8: skprnz %o0
+ br 9f
+ subi %o0, 1 /* cnt--, Delay slot */
+ br 8b
+ nop
+
+9: lret
+ nop /* Delay slot */
+
+
+ .data
+ .globl version_string
+
+version_string:
+ .ascii U_BOOT_VERSION
+ .ascii " (", __DATE__, " - ", __TIME__, ")"
+ .ascii CONFIG_IDENT_STRING, "\0"