MIPS: Ingenic XBurst Jz4740 processor support

Jz4740 is a multimedia application processor targeting for mobile
devices like e-Dictionary, eBook, portable media player (PMP) and
GPS navigator.  Jz4740 is powered by Ingenic 360 MHz XBurst CPU core
(JzRISC), in which RISC/SIMD/DSP hybrid instruction set architecture
provides high integration, high performance and low power consumption.

JzRISC incorporated in Jz4740 is the advanced and power-efficient
32-bit RISC core, compatible with MIPS32, with 16K I-Cache and 16K
D-Cache, and can operate at speeds up to 400 MHz.

On-chip modules such as LCD controller, embedded audio codec, multi-
channel SAR-ADC, AC97/I2S controller and camera I/F offer a rich
suite of peripherals for multimedia application.  NAND controller
(SLC/MLC), USB (host 1.1 and device 2.0), UART, I2C, SPI, etc. are
also available.

For more info about Ingenic XBurst Jz4740:
  http://en.ingenic.cn/eng/
  http://www.linux-mips.org/wiki/Ingenic

This patch introduces XBurst CPU support in U-Boot.  It's compatible
with MIPS32, but requires a bit different cache maintenance, timer
routines, and boot mechanism using USB boot tool, so XBurst support
can go into a separate new home, cpu/xburst/.

Signed-off-by: Xiangfu Liu <xiangfu@openmobilefree.net>
Acked-by: Daniel <zpxu@ingenic.cn>
Signed-off-by: Shinya Kuribayashi <skuribay@pobox.com>
diff --git a/arch/mips/cpu/xburst/start.S b/arch/mips/cpu/xburst/start.S
new file mode 100644
index 0000000..d846104
--- /dev/null
+++ b/arch/mips/cpu/xburst/start.S
@@ -0,0 +1,171 @@
+/*
+ *  Startup Code for MIPS32 XBURST CPU-core
+ *
+ *  Copyright (c) 2010 Xiangfu Liu <xiangfu@sharism.cc>
+ *
+ * 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>
+#include <asm/regdef.h>
+#include <asm/mipsregs.h>
+#include <asm/addrspace.h>
+#include <asm/cacheops.h>
+
+	.set noreorder
+
+	.globl _start
+	.text
+_start:
+	/* Initialize $gp */
+	bal	1f
+	 nop
+	.word	_gp
+1:
+	lw	gp, 0(ra)
+
+	/* Set up temporary stack */
+	li	sp, CONFIG_SYS_SDRAM_BASE + CONFIG_SYS_INIT_SP_OFFSET
+
+	la	t9, board_init_f
+	jr	t9
+	 nop
+
+/*
+ * void relocate_code (addr_sp, gd, addr_moni)
+ *
+ * This "function" does not return, instead it continues in RAM
+ * after relocating the monitor code.
+ *
+ * a0 = addr_sp
+ * a1 = gd
+ * a2 = destination address
+ */
+	.globl	relocate_code
+	.ent	relocate_code
+relocate_code:
+	move	sp, a0			# set new stack pointer
+
+	li	t0, CONFIG_SYS_MONITOR_BASE
+	la	t3, in_ram
+	lw	t2, -12(t3)		# t2 <-- uboot_end_data
+	move	t1, a2
+
+	/*
+	 * Fix $gp:
+	 *
+	 * New $gp = (Old $gp - CONFIG_SYS_MONITOR_BASE) + Destination Address
+	 */
+	move	t6, gp
+	sub	gp, CONFIG_SYS_MONITOR_BASE
+	add	gp, a2			# gp now adjusted
+	sub	t6, gp, t6		# t6 <-- relocation offset
+
+	/*
+	 * t0 = source address
+	 * t1 = target address
+	 * t2 = source end address
+	 */
+1:
+	lw	t3, 0(t0)
+	sw	t3, 0(t1)
+	addu	t0, 4
+	ble	t0, t2, 1b
+	 addu	t1, 4
+
+	/* If caches were enabled, we would have to flush them here. */
+
+	/* flush d-cache */
+	li	t0, KSEG0
+	addi	t1, t0, CONFIG_SYS_DCACHE_SIZE
+2:
+	cache	Index_Writeback_Inv_D, 0(t0)
+	bne	t0, t1, 2b
+	 addi	t0, CONFIG_SYS_CACHELINE_SIZE
+
+	sync
+
+	/* flush i-cache */
+	li	t0, KSEG0
+	addi	t1, t0, CONFIG_SYS_ICACHE_SIZE
+3:
+	cache	Index_Invalidate_I, 0(t0)
+	bne	t0, t1, 3b
+	 addi	t0, CONFIG_SYS_CACHELINE_SIZE
+
+	/* Invalidate BTB */
+	mfc0	t0, CP0_CONFIG, 7
+	nop
+	ori	t0, 2
+	mtc0	t0, CP0_CONFIG, 7
+	nop
+
+	/* Jump to where we've relocated ourselves */
+	addi	t0, a2, in_ram - _start
+	jr	t0
+	 nop
+
+	.word	_gp
+	.word	_GLOBAL_OFFSET_TABLE_
+	.word	uboot_end_data
+	.word	uboot_end
+	.word	num_got_entries
+
+in_ram:
+	/*
+	 * Now we want to update GOT.
+	 *
+	 * GOT[0] is reserved. GOT[1] is also reserved for the dynamic object
+	 * generated by GNU ld. Skip these reserved entries from relocation.
+	 */
+	lw	t3, -4(t0)		# t3 <-- num_got_entries
+	lw	t4, -16(t0)		# t4 <-- _GLOBAL_OFFSET_TABLE_
+	lw	t5, -20(t0)		# t5 <-- _gp
+	sub	t4, t5			# compute offset
+	add	t4, t4, gp		# t4 now holds relocated _G_O_T_
+	addi	t4, t4, 8		# skipping first two entries
+	li	t2, 2
+1:
+	lw	t1, 0(t4)
+	beqz	t1, 2f
+	 add	t1, t6
+	sw	t1, 0(t4)
+2:
+	addi	t2, 1
+	blt	t2, t3, 1b
+	 addi	t4, 4
+
+	/* Clear BSS */
+	lw	t1, -12(t0)		# t1 <-- uboot_end_data
+	lw	t2, -8(t0)		# t2 <-- uboot_end
+	add	t1, t6			# adjust pointers
+	add	t2, t6
+
+	sub	t1, 4
+1:	addi	t1, 4
+	bltl	t1, t2, 1b
+	 sw	zero, 0(t1)
+
+	move	a0, a1			# a0 <-- gd
+	la	t9, board_init_r
+	jr	t9
+	 move	a1, a2
+
+	.end	relocate_code