board/zylonite/lowlevel_init.S - uboot/prism - Git at Google

 /*
  * Most of this taken from Redboot hal_platform_setup.h with cleanup
  *
  * NOTE: I haven't clean this up considerably, just enough to get it
  * running. See hal_platform_setup.h for the source. See
  * board/cradle/lowlevel_init.S for another PXA250 setup that is
  * much cleaner.
  *
  * 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/arch/pxa-regs.h>

 DRAM_SIZE:  .long   CONFIG_SYS_DRAM_SIZE

 /* wait for coprocessor write complete */
 .macro CPWAIT reg
 	mrc	p15,0,\reg,c2,c0,0
 	mov	\reg,\reg
 	sub	pc,pc,#4
 .endm


 .macro wait time
 	ldr		r2, =OSCR
 	mov		r3, #0
 	str		r3, [r2]
 0:
 	ldr		r3, [r2]
 	cmp		r3, \time
 	bls		0b
 .endm

 /*
  *	Memory setup
  */

 .globl lowlevel_init
 lowlevel_init:
 	/* Set up GPIO pins first ----------------------------------------- */
 	mov	 r10, lr

 	/*  Configure GPIO Pins 41 - 48 as UART1 / altern. Fkt. 2 */
 	ldr		r0, =0x40E10438 @ GPIO41 FFRXD
 	ldr		r1, =0x802
 	str		r1, [r0]

 	ldr		r0, =0x40E1043C @ GPIO42 FFTXD
 	ldr		r1, =0x802
 	str		r1, [r0]

 	ldr		r0, =0x40E10440 @ GPIO43 FFCTS
 	ldr		r1, =0x802
 	str		r1, [r0]

 	ldr		r0, =0x40E10444 @ GPIO 44 FFDCD
 	ldr		r1, =0x802
 	str		r1, [r0]

 	ldr		r0, =0x40E10448 @ GPIO 45 FFDSR
 	ldr		r1, =0x802
 	str		r1, [r0]

 	ldr		r0, =0x40E1044C @ GPIO 46 FFRI
 	ldr		r1, =0x802
 	str		r1, [r0]

 	ldr		r0, =0x40E10450 @ GPIO 47 FFDTR
 	ldr		r1, =0x802
 	str		r1, [r0]

 	ldr		r0, =0x40E10454 @ GPIO 48
 	ldr		r1, =0x802
 	str		r1, [r0]

 	/* tebrandt - ASCR, clear the RDH bit */
 	ldr		r0, =ASCR
 	ldr		r1, [r0]
 	bic		r1, r1, #0x80000000
 	str		r1, [r0]

 	/* ---------------------------------------------------------------- */
 	/* Enable memory interface					    */
 	/*								    */
 	/* The sequence below is based on the recommended init steps	    */
 	/* detailed in the Intel PXA250 Operating Systems Developers Guide, */
 	/* Chapter 10.							    */
 	/* ---------------------------------------------------------------- */

 	/* ---------------------------------------------------------------- */
 	/* Step 1: Wait for at least 200 microsedonds to allow internal	    */
 	/*	   clocks to settle. Only necessary after hard reset...	    */
 	/*	   FIXME: can be optimized later			    */
 	/* ---------------------------------------------------------------- */

 	/* mk:	 replaced with wait macro */
 /*	ldr r3, =OSCR			/\* reset the OS Timer Count to zero *\/ */
 /*	mov r2, #0 */
 /*	str r2, [r3] */
 /*	ldr r4, =0x300			/\* really 0x2E1 is about 200usec,   *\/ */
 /*					/\* so 0x300 should be plenty	     *\/ */
 /* 1: */
 /*	ldr r2, [r3] */
 /*	cmp r4, r2 */
 /*	bgt 1b */
 	wait #0x300

 mem_init:

 	/* configure the MEMCLKCFG register */
 	ldr		r1, =MEMCLKCFG
 	ldr		r2, =0x00010001
 	str		r2, [r1]	     @ WRITE
 	ldr		r2, [r1]	     @ DELAY UNTIL WRITTEN

 	/* set CSADRCFG[0] to data flash SRAM mode */
 	ldr		r1, =CSADRCFG0
 	ldr		r2, =0x00320809
 	str		r2, [r1]	     @ WRITE
 	ldr		r2, [r1]	     @ DELAY UNTIL WRITTEN

 	/* set CSADRCFG[1] to data flash SRAM mode */
 	ldr		r1, =CSADRCFG1
 	ldr		r2, =0x00320809
 	str		r2, [r1]	     @ WRITE
 	ldr		r2, [r1]	     @ DELAY UNTIL WRITTEN

 	/* set MSC 0 register for SRAM memory */
 	ldr		r1, =MSC0
 	ldr		r2, =0x11191119
 	str		r2, [r1]	     @ WRITE
 	ldr		r2, [r1]	     @ DELAY UNTIL WRITTEN

 	/* set CSADRCFG[2] to data flash SRAM mode */
 	ldr		r1, =CSADRCFG2
 	ldr		r2, =0x00320809
 	str		r2, [r1]	     @ WRITE
 	ldr		r2, [r1]	     @ DELAY UNTIL WRITTEN

 	/* set CSADRCFG[3] to VLIO mode */
 	ldr		r1, =CSADRCFG3
 	ldr		r2, =0x0032080B
 	str		r2, [r1]	     @ WRITE
 	ldr		r2, [r1]	     @ DELAY UNTIL WRITTEN

 	/* set MSC 1 register for VLIO memory */
 	ldr		r1, =MSC1
 	ldr		r2, =0x123C1119
 	str		r2, [r1]	     @ WRITE
 	ldr		r2, [r1]	     @ DELAY UNTIL WRITTEN

 #if 0
 	/* This does not work in Zylonite. -SC */
 	ldr		r0, =0x15fffff0
 	ldr		r1, =0xb10b
 	str		r1, [r0]
 	str		r1, [r0, #4]
 #endif

 	/* Configure ACCR Register */
 	ldr		r0, =ACCR		@ ACCR
 	ldr		r1, =0x0180b108
 	str		r1, [r0]
 	ldr		r1, [r0]

 	/* Configure MDCNFG Register */
 	ldr		r0, =MDCNFG		@ MDCNFG
 	ldr		r1, =0x403
 	str		r1, [r0]
 	ldr		r1, [r0]

 	/* Perform Resistive Compensation by configuring RCOMP register */
 	ldr		r1, =RCOMP		@ RCOMP
 	ldr		r2, =0x000000ff
 	str		r2, [r1]
 	ldr		r2, [r1]

 	/* Configure MDMRS Register for SDCS0 */
 	ldr		r1, =MDMRS		@ MDMRS
 	ldr		r2, =0x60000023
 	ldr		r3, [r1]
 	orr		r2, r2, r3
 	str		r2, [r1]
 	ldr		r2, [r1]

 	/* Configure MDMRS Register for SDCS1 */
 	ldr		r1, =MDMRS		@ MDMRS
 	ldr		r2, =0xa0000023
 	ldr		r3, [r1]
 	orr		r2, r2, r3
 	str		r2, [r1]
 	ldr		r2, [r1]

 	/* Configure MDREFR */
 	ldr		r1, =MDREFR		@ MDREFR
 	ldr		r2, =0x00000006
 	str		r2, [r1]
 	ldr		r2, [r1]

 	/* Configure EMPI */
 	ldr		r1, =EMPI		@ EMPI
 	ldr		r2, =0x80000000
 	str		r2, [r1]
 	ldr		r2, [r1]

 	/* Hardware DDR Read-Strobe Delay Calibration */
 	ldr		r0, =DDR_HCAL		@ DDR_HCAL
 	ldr		r1, =0x803ffc07	    @ the offset is correct? -SC
 	str		r1, [r0]
 	wait		#5
 	ldr		r1, [r0]

 	/* Here we assume the hardware calibration alwasy be successful. -SC */
 	/* Set DMCEN bit in MDCNFG Register */
 	ldr		r0, =MDCNFG		@ MDCNFG
 	ldr		r1, [r0]
 	orr		r1, r1, #0x40000000	@ enable SDRAM for Normal Access
 	str		r1, [r0]

 #ifndef CONFIG_SYS_SKIP_DRAM_SCRUB
 	/* scrub/init SDRAM if enabled/present */
 /*	ldr	r11, =0xa0000000 /\* base address of SDRAM (CONFIG_SYS_DRAM_BASE) *\/ */
 /*	ldr	r12, =0x04000000 /\* size of memory to scrub (CONFIG_SYS_DRAM_SIZE) *\/ */
 /*	mov	r8,r12		 /\* save DRAM size (mk: why???) *\/ */
 	ldr	r8, =0xa0000000	 /* base address of SDRAM (CONFIG_SYS_DRAM_BASE) */
 	ldr	r9, =0x04000000	 /* size of memory to scrub (CONFIG_SYS_DRAM_SIZE) */
 	mov	r0, #0		 /* scrub with 0x0000:0000 */
 	mov	r1, #0
 	mov	r2, #0
 	mov	r3, #0
 	mov	r4, #0
 	mov	r5, #0
 	mov	r6, #0
 	mov	r7, #0
 10:	/* fastScrubLoop */
 	subs	r9, r9, #32	/* 32 bytes/line */
 	stmia	r8!, {r0-r7}
 	beq	15f
 	b	10b
 #endif /* CONFIG_SYS_SKIP_DRAM_SCRUB */

 15:
 	/* Mask all interrupts */
 	mov	r1, #0
 	mcr	p6, 0, r1, c1, c0, 0	@ ICMR

 	/* Disable software and data breakpoints */
 	mov	r0, #0
 	mcr	p15,0,r0,c14,c8,0  /* ibcr0 */
 	mcr	p15,0,r0,c14,c9,0  /* ibcr1 */
 	mcr	p15,0,r0,c14,c4,0  /* dbcon */

 	/* Enable all debug functionality */
 	mov	r0,#0x80000000
 	mcr	p14,0,r0,c10,c0,0  /* dcsr */

 	/* We are finished with Intel's memory controller initialisation    */

 	/* ---------------------------------------------------------------- */
 	/* End lowlevel_init							 */
 	/* ---------------------------------------------------------------- */

 endlowlevel_init:

 	mov	pc, lr

 /*
 @********************************************************************************
 @ DDR calibration
 @
 @  This function is used to calibrate DQS delay lines.
 @ Monahans supports three ways to do it. One is software
 @ calibration. Two is hardware calibration. Three is hybrid
 @ calibration.
 @
 @ TBD
 @ -SC
 ddr_calibration:

 	@ Case 1:	Write the correct delay value once
 	@ Configure DDR_SCAL Register
 	ldr	r0, =DDR_SCAL		@ DDR_SCAL
 q	ldr	r1, =0xaf2f2f2f
 	str	r1, [r0]
 	ldr	r1, [r0]
 */
 /*	@ Case 2:	Software Calibration
 	@ Write test pattern to memory
 	ldr	r5, =0x0faf0faf		@ Data Pattern
 	ldr	r4, =0xa0000000		@ DDR ram
 	str	r5, [r4]

 	mov	r1, =0x0		@ delay count
 	mov	r6, =0x0
 	mov	r7, =0x0
 ddr_loop1:
 	add	r1, r1, =0x1
 	cmp	r1, =0xf
 	ble	end_loop
 	mov	r3, r1
 	mov	r0, r1, lsl #30
 	orr	r3, r3, r0
 	mov	r0, r1, lsl #22
 	orr	r3, r3, r0
 	mov	r0, r1, lsl #14
 	orr	r3, r3, r0
 	orr	r3, r3, =0x80000000
 	ldr	r2, =DDR_SCAL
 	str	r3, [r2]

 	ldr	r2, [r4]
 	cmp	r2, r5
 	bne	ddr_loop1
 	mov	r6, r1
 ddr_loop2:
 	add	r1, r1, =0x1
 	cmp	r1, =0xf
 	ble	end_loop
 	mov	r3, r1
 	mov	r0, r1, lsl #30
 	orr	r3, r3, r0
 	mov	r0, r1, lsl #22
 	orr	r3, r3, r0
 	mov	r0, r1, lsl #14
 	orr	r3, r3, r0
 	orr	r3, r3, =0x80000000
 	ldr	r2, =DDR_SCAL
 	str	r3, [r2]

 	ldr	r2, [r4]
 	cmp	r2, r5
 	be	ddr_loop2
 	mov	r7, r2

 	add	r3, r6, r7
 	lsr	r3, r3, =0x1
 	mov	r0, r1, lsl #30
 	orr	r3, r3, r0
 	mov	r0, r1, lsl #22
 	orr	r3, r3, r0
 	mov	r0, r1, lsl #14
 	orr	r3, r3, r0
 	orr	r3, r3, =0x80000000
 	ldr	r2, =DDR_SCAL

 end_loop:

 	@ Case 3:	Hardware Calibratoin
 	ldr	r0, =DDR_HCAL		@ DDR_HCAL
 	ldr	r1, =0x803ffc07	    @ the offset is correct? -SC
 	str	r1, [r0]
 	wait	#5
 	ldr	r1, [r0]
 	mov	pc, lr
 */
	/*
	* Most of this taken from Redboot hal_platform_setup.h with cleanup
	*
	* NOTE: I haven't clean this up considerably, just enough to get it
	* running. See hal_platform_setup.h for the source. See
	* board/cradle/lowlevel_init.S for another PXA250 setup that is
	* much cleaner.
	*
	* 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/arch/pxa-regs.h>

	DRAM_SIZE: .long CONFIG_SYS_DRAM_SIZE

	/* wait for coprocessor write complete */
	.macro CPWAIT reg
	mrc p15,0,\reg,c2,c0,0
	mov \reg,\reg
	sub pc,pc,#4
	.endm


	.macro wait time
	ldr r2, =OSCR
	mov r3, #0
	str r3, [r2]
	0:
	ldr r3, [r2]
	cmp r3, \time
	bls 0b
	.endm

	/*
	* Memory setup
	*/

	.globl lowlevel_init
	lowlevel_init:
	/* Set up GPIO pins first ----------------------------------------- */
	mov r10, lr

	/* Configure GPIO Pins 41 - 48 as UART1 / altern. Fkt. 2 */
	ldr r0, =0x40E10438 @ GPIO41 FFRXD
	ldr r1, =0x802
	str r1, [r0]

	ldr r0, =0x40E1043C @ GPIO42 FFTXD
	ldr r1, =0x802
	str r1, [r0]

	ldr r0, =0x40E10440 @ GPIO43 FFCTS
	ldr r1, =0x802
	str r1, [r0]

	ldr r0, =0x40E10444 @ GPIO 44 FFDCD
	ldr r1, =0x802
	str r1, [r0]

	ldr r0, =0x40E10448 @ GPIO 45 FFDSR
	ldr r1, =0x802
	str r1, [r0]

	ldr r0, =0x40E1044C @ GPIO 46 FFRI
	ldr r1, =0x802
	str r1, [r0]

	ldr r0, =0x40E10450 @ GPIO 47 FFDTR
	ldr r1, =0x802
	str r1, [r0]

	ldr r0, =0x40E10454 @ GPIO 48
	ldr r1, =0x802
	str r1, [r0]

	/* tebrandt - ASCR, clear the RDH bit */
	ldr r0, =ASCR
	ldr r1, [r0]
	bic r1, r1, #0x80000000
	str r1, [r0]

	/* ---------------------------------------------------------------- */
	/* Enable memory interface */
	/* */
	/* The sequence below is based on the recommended init steps */
	/* detailed in the Intel PXA250 Operating Systems Developers Guide, */
	/* Chapter 10. */
	/* ---------------------------------------------------------------- */

	/* ---------------------------------------------------------------- */
	/* Step 1: Wait for at least 200 microsedonds to allow internal */
	/* clocks to settle. Only necessary after hard reset... */
	/* FIXME: can be optimized later */
	/* ---------------------------------------------------------------- */

	/* mk: replaced with wait macro */
	/* ldr r3, =OSCR /\* reset the OS Timer Count to zero \/ /
	/* mov r2, #0 */
	/* str r2, [r3] */
	/* ldr r4, =0x300 /\* really 0x2E1 is about 200usec, \/ /
	/* /\* so 0x300 should be plenty \/ /
	/* 1: */
	/* ldr r2, [r3] */
	/* cmp r4, r2 */
	/* bgt 1b */
	wait #0x300

	mem_init:

	/* configure the MEMCLKCFG register */
	ldr r1, =MEMCLKCFG
	ldr r2, =0x00010001
	str r2, [r1] @ WRITE
	ldr r2, [r1] @ DELAY UNTIL WRITTEN

	/* set CSADRCFG[0] to data flash SRAM mode */
	ldr r1, =CSADRCFG0
	ldr r2, =0x00320809
	str r2, [r1] @ WRITE
	ldr r2, [r1] @ DELAY UNTIL WRITTEN

	/* set CSADRCFG[1] to data flash SRAM mode */
	ldr r1, =CSADRCFG1
	ldr r2, =0x00320809
	str r2, [r1] @ WRITE
	ldr r2, [r1] @ DELAY UNTIL WRITTEN

	/* set MSC 0 register for SRAM memory */
	ldr r1, =MSC0
	ldr r2, =0x11191119
	str r2, [r1] @ WRITE
	ldr r2, [r1] @ DELAY UNTIL WRITTEN

	/* set CSADRCFG[2] to data flash SRAM mode */
	ldr r1, =CSADRCFG2
	ldr r2, =0x00320809
	str r2, [r1] @ WRITE
	ldr r2, [r1] @ DELAY UNTIL WRITTEN

	/* set CSADRCFG[3] to VLIO mode */
	ldr r1, =CSADRCFG3
	ldr r2, =0x0032080B
	str r2, [r1] @ WRITE
	ldr r2, [r1] @ DELAY UNTIL WRITTEN

	/* set MSC 1 register for VLIO memory */
	ldr r1, =MSC1
	ldr r2, =0x123C1119
	str r2, [r1] @ WRITE
	ldr r2, [r1] @ DELAY UNTIL WRITTEN

	#if 0
	/* This does not work in Zylonite. -SC */
	ldr r0, =0x15fffff0
	ldr r1, =0xb10b
	str r1, [r0]
	str r1, [r0, #4]
	#endif

	/* Configure ACCR Register */
	ldr r0, =ACCR @ ACCR
	ldr r1, =0x0180b108
	str r1, [r0]
	ldr r1, [r0]

	/* Configure MDCNFG Register */
	ldr r0, =MDCNFG @ MDCNFG
	ldr r1, =0x403
	str r1, [r0]
	ldr r1, [r0]

	/* Perform Resistive Compensation by configuring RCOMP register */
	ldr r1, =RCOMP @ RCOMP
	ldr r2, =0x000000ff
	str r2, [r1]
	ldr r2, [r1]

	/* Configure MDMRS Register for SDCS0 */
	ldr r1, =MDMRS @ MDMRS
	ldr r2, =0x60000023
	ldr r3, [r1]
	orr r2, r2, r3
	str r2, [r1]
	ldr r2, [r1]

	/* Configure MDMRS Register for SDCS1 */
	ldr r1, =MDMRS @ MDMRS
	ldr r2, =0xa0000023
	ldr r3, [r1]
	orr r2, r2, r3
	str r2, [r1]
	ldr r2, [r1]

	/* Configure MDREFR */
	ldr r1, =MDREFR @ MDREFR
	ldr r2, =0x00000006
	str r2, [r1]
	ldr r2, [r1]

	/* Configure EMPI */
	ldr r1, =EMPI @ EMPI
	ldr r2, =0x80000000
	str r2, [r1]
	ldr r2, [r1]

	/* Hardware DDR Read-Strobe Delay Calibration */
	ldr r0, =DDR_HCAL @ DDR_HCAL
	ldr r1, =0x803ffc07 @ the offset is correct? -SC
	str r1, [r0]
	wait #5
	ldr r1, [r0]

	/* Here we assume the hardware calibration alwasy be successful. -SC */
	/* Set DMCEN bit in MDCNFG Register */
	ldr r0, =MDCNFG @ MDCNFG
	ldr r1, [r0]
	orr r1, r1, #0x40000000 @ enable SDRAM for Normal Access
	str r1, [r0]

	#ifndef CONFIG_SYS_SKIP_DRAM_SCRUB
	/* scrub/init SDRAM if enabled/present */
	/* ldr r11, =0xa0000000 /\* base address of SDRAM (CONFIG_SYS_DRAM_BASE) \/ /
	/* ldr r12, =0x04000000 /\* size of memory to scrub (CONFIG_SYS_DRAM_SIZE) \/ /
	/* mov r8,r12 /\* save DRAM size (mk: why???) \/ /
	ldr r8, =0xa0000000 /* base address of SDRAM (CONFIG_SYS_DRAM_BASE) */
	ldr r9, =0x04000000 /* size of memory to scrub (CONFIG_SYS_DRAM_SIZE) */
	mov r0, #0 /* scrub with 0x0000:0000 */
	mov r1, #0
	mov r2, #0
	mov r3, #0
	mov r4, #0
	mov r5, #0
	mov r6, #0
	mov r7, #0
	10: /* fastScrubLoop */
	subs r9, r9, #32 /* 32 bytes/line */
	stmia r8!, {r0-r7}
	beq 15f
	b 10b
	#endif /* CONFIG_SYS_SKIP_DRAM_SCRUB */

	15:
	/* Mask all interrupts */
	mov r1, #0
	mcr p6, 0, r1, c1, c0, 0 @ ICMR

	/* Disable software and data breakpoints */
	mov r0, #0
	mcr p15,0,r0,c14,c8,0 /* ibcr0 */
	mcr p15,0,r0,c14,c9,0 /* ibcr1 */
	mcr p15,0,r0,c14,c4,0 /* dbcon */

	/* Enable all debug functionality */
	mov r0,#0x80000000
	mcr p14,0,r0,c10,c0,0 /* dcsr */

	/* We are finished with Intel's memory controller initialisation */

	/* ---------------------------------------------------------------- */
	/* End lowlevel_init */
	/* ---------------------------------------------------------------- */

	endlowlevel_init:

	mov pc, lr

	/*
	@********************************************************************************
	@ DDR calibration
	@
	@ This function is used to calibrate DQS delay lines.
	@ Monahans supports three ways to do it. One is software
	@ calibration. Two is hardware calibration. Three is hybrid
	@ calibration.
	@
	@ TBD
	@ -SC
	ddr_calibration:

	@ Case 1: Write the correct delay value once
	@ Configure DDR_SCAL Register
	ldr r0, =DDR_SCAL @ DDR_SCAL
	q ldr r1, =0xaf2f2f2f
	str r1, [r0]
	ldr r1, [r0]
	*/
	/* @ Case 2: Software Calibration
	@ Write test pattern to memory
	ldr r5, =0x0faf0faf @ Data Pattern
	ldr r4, =0xa0000000 @ DDR ram
	str r5, [r4]

	mov r1, =0x0 @ delay count
	mov r6, =0x0
	mov r7, =0x0
	ddr_loop1:
	add r1, r1, =0x1
	cmp r1, =0xf
	ble end_loop
	mov r3, r1
	mov r0, r1, lsl #30
	orr r3, r3, r0
	mov r0, r1, lsl #22
	orr r3, r3, r0
	mov r0, r1, lsl #14
	orr r3, r3, r0
	orr r3, r3, =0x80000000
	ldr r2, =DDR_SCAL
	str r3, [r2]

	ldr r2, [r4]
	cmp r2, r5
	bne ddr_loop1
	mov r6, r1
	ddr_loop2:
	add r1, r1, =0x1
	cmp r1, =0xf
	ble end_loop
	mov r3, r1
	mov r0, r1, lsl #30
	orr r3, r3, r0
	mov r0, r1, lsl #22
	orr r3, r3, r0
	mov r0, r1, lsl #14
	orr r3, r3, r0
	orr r3, r3, =0x80000000
	ldr r2, =DDR_SCAL
	str r3, [r2]

	ldr r2, [r4]
	cmp r2, r5
	be ddr_loop2
	mov r7, r2

	add r3, r6, r7
	lsr r3, r3, =0x1
	mov r0, r1, lsl #30
	orr r3, r3, r0
	mov r0, r1, lsl #22
	orr r3, r3, r0
	mov r0, r1, lsl #14
	orr r3, r3, r0
	orr r3, r3, =0x80000000
	ldr r2, =DDR_SCAL

	end_loop:

	@ Case 3: Hardware Calibratoin
	ldr r0, =DDR_HCAL @ DDR_HCAL
	ldr r1, =0x803ffc07 @ the offset is correct? -SC
	str r1, [r0]
	wait #5
	ldr r1, [r0]
	mov pc, lr
	*/