Hexagon: Add startup code

Signed-off-by: Richard Kuo <rkuo@codeaurora.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 162 insertions, 0 deletions

diff --git a/arch/hexagon/kernel/head.S b/arch/hexagon/kernel/head.S
new file mode 100644
index 000000000000..8e6b819125a3
--- /dev/null
+++ b/arch/hexagon/kernel/head.S
@@ -0,0 +1,162 @@
+/*
+ * Early kernel startup code for Hexagon
+ *
+ * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
+ *
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+#include <linux/linkage.h>
+#include <linux/init.h>
+#include <asm/asm-offsets.h>
+#include <asm/mem-layout.h>
+#include <asm/vm_mmu.h>
+#include <asm/page.h>
+
+	__INIT
+ENTRY(stext)
+	/*
+	 * VMM will already have set up true vector page, MMU, etc.
+	 * To set up initial kernel identity map, we have to pass
+	 * the VMM a pointer to some canonical page tables. In
+	 * this implementation, we're assuming that we've got
+	 * them precompiled. Generate value in R24, as we'll need
+	 * it again shortly.
+	 */
+	r24.L = #LO(swapper_pg_dir)
+	r24.H = #HI(swapper_pg_dir)
+
+	/*
+	 * Symbol is kernel segment address, but we need
+	 * the logical/physical address.
+	 */
+	r24 = asl(r24, #2)
+	r24 = lsr(r24, #2)
+
+	r0 = r24
+
+	/*
+	 * Initialize a 16MB PTE to make the virtual and physical
+	 * addresses where the kernel was loaded be identical.
+	 */
+#define PTE_BITS ( __HVM_PTE_R | __HVM_PTE_W | __HVM_PTE_X	\
+		  | __HEXAGON_C_WB_L2 << 6			\
+		  | __HVM_PDE_S_4MB)
+
+	r1 = pc
+	r2.H = #0xffc0
+	r2.L = #0x0000
+	r1 = and(r1,r2)		/* round PC to 4MB boundary	*/
+	r2 = lsr(r1, #22)	/* 4MB page number		*/
+	r2 = asl(r2, #2)	/* times sizeof(PTE) (4bytes)	*/
+	r0 = add(r0,r2)		/* r0 = address of correct PTE	*/
+	r2 = #PTE_BITS
+	r1 = add(r1,r2)		/* r1 = 4MB PTE for the first entry	*/
+	r2.h = #0x0040
+	r2.l = #0x0000		/* 4MB	*/
+	memw(r0 ++ #4) = r1
+	r1 = add(r1, r2)
+	memw(r0 ++ #4) = r1
+
+	r0 = r24
+
+	/*
+	 * The subroutine wrapper around the virtual instruction touches
+	 * no memory, so we should be able to use it even here.
+	 */
+	call	__vmnewmap;
+
+	/*  Jump into virtual address range.  */
+
+	r31.h = #hi(__head_s_vaddr_target)
+	r31.l = #lo(__head_s_vaddr_target)
+	jumpr r31
+
+	/*  Insert trippy space effects.  */
+
+__head_s_vaddr_target:
+	/*
+	 * Tear down VA=PA translation now that we are running
+	 * in the desgnated kernel segments.
+	 */
+	r0 = #__HVM_PDE_S_INVALID
+	r1 = r24
+	loop0(1f,#0x100)
+1:
+	{
+		memw(R1 ++ #4) = R0
+	}:endloop0
+
+	r0 = r24
+	call __vmnewmap
+
+	/*  Go ahead and install the trap0 return so angel calls work  */
+	r0.h = #hi(_K_provisional_vec)
+	r0.l = #lo(_K_provisional_vec)
+	call __vmsetvec
+
+	/*
+	 * OK, at this point we should start to be much more careful,
+	 * we're going to enter C code and start touching memory
+	 * in all sorts of places.
+	 * This means:
+	 *      SGP needs to be OK
+	 *	Need to lock shared resources
+	 *	A bunch of other things that will cause
+	 * 	all kinds of painful bugs
+	 */
+
+	/*
+	 * Stack pointer should be pointed at the init task's
+	 * thread stack, which should have been declared in arch/init_task.c.
+	 * So uhhhhh...
+	 * It's accessible via the init_thread_union, which is a union
+	 * of a thread_info struct and a stack; of course, the top
+	 * of the stack is not for you.  The end of the stack
+	 * is simply init_thread_union + THREAD_SIZE.
+	 */
+
+	{r29.H = #HI(init_thread_union); r0.H = #HI(_THREAD_SIZE); }
+	{r29.L = #LO(init_thread_union); r0.L = #LO(_THREAD_SIZE); }
+
+	/*  initialize the register used to point to current_thread_info */
+	/*  Fixme:  THREADINFO_REG can't be R2 because of that memset thing. */
+	{r29 = add(r29,r0); THREADINFO_REG = r29; }
+
+	/*  Hack:  zero bss; */
+	{ r0.L = #LO(__bss_start);  r1 = #0; r2.l = #LO(__bss_stop); }
+	{ r0.H = #HI(__bss_start);           r2.h = #HI(__bss_stop); }
+
+	r2 = sub(r2,r0);
+	call memset;
+
+	/* Time to make the doughnuts.   */
+	call start_kernel
+
+	/*
+	 * Should not reach here.
+	 */
+1:
+	jump 1b
+
+.p2align PAGE_SHIFT
+ENTRY(external_cmdline_buffer)
+        .fill _PAGE_SIZE,1,0
+
+.data
+.p2align PAGE_SHIFT
+ENTRY(empty_zero_page)
+        .fill _PAGE_SIZE,1,0