ARC: Boot #1: low-level, setup_arch(), /proc/cpuinfo, mem init

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

arch/arc/kernel/head.S

@@ -0,0 +1,78 @@
+/*
+ * ARC CPU startup Code
+ *
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Vineetg: Dec 2007
+ *  -Check if we are running on Simulator or on real hardware
+ *      to skip certain things during boot on simulator
+ */
+
+#include <asm/asm-offsets.h>
+#include <asm/entry.h>
+#include <linux/linkage.h>
+#include <asm/arcregs.h>
+
+	.cpu A7
+
+	.section .init.text, "ax",@progbits
+	.type stext, @function
+	.globl stext
+stext:
+	;-------------------------------------------------------------------
+	; Don't clobber r0-r4 yet. It might have bootloader provided info
+	;-------------------------------------------------------------------
+
+	; Clear BSS before updating any globals
+	; XXX: use ZOL here
+	mov	r5, __bss_start
+	mov	r6, __bss_stop
+1:
+	st.ab   0, [r5,4]
+	brlt    r5, r6, 1b
+
+#ifdef CONFIG_CMDLINE_UBOOT
+	; support for bootloader provided cmdline
+	;    If cmdline passed by u-boot, then
+	;    r0 = 1  (because ATAGS parsing, now retired, used to use 0)
+	;    r1 = magic number (board identity)
+	;    r2 = addr of cmdline string (somewhere in memory/flash)
+
+	brne	r0, 1, .Lother_bootup_chores	; u-boot didn't pass cmdline
+	breq	r2, 0, .Lother_bootup_chores	; or cmdline is NULL
+
+	mov	r5, @command_line
+1:
+	ldb.ab  r6, [r2, 1]
+	breq    r6, 0, .Lother_bootup_chores
+	b.d     1b
+	stb.ab  r6, [r5, 1]
+#endif
+
+.Lother_bootup_chores:
+
+	; Identify if running on ISS vs Silicon
+	; 	IDENTITY Reg [ 3  2  1  0 ]
+	;	(chip-id)      ^^^^^		==> 0xffff for ISS
+	lr	r0, [identity]
+	lsr	r3, r0, 16
+	cmp	r3, 0xffff
+	mov.z	r4, 0
+	mov.nz	r4, 1
+	st	r4, [@running_on_hw]
+
+	; setup "current" tsk and optionally cache it in dedicated r25
+	mov	r9, @init_task
+	SET_CURR_TASK_ON_CPU  r9, r0	; r9 = tsk, r0 = scratch
+
+	; setup stack (fp, sp)
+	mov	fp, 0
+
+	; tsk->thread_info is really a PAGE, whose bottom hoists stack
+	GET_TSK_STACK_BASE r9, sp	; r9 = tsk, sp = stack base(output)
+
+	j	start_kernel	; "C" entry point