ppc4xx/NAND_SPL: Consolidate 405 and 440 NAND booting code in start.S

This patch consolidates the 405 and 440 parts of the NAND booting code
selected via CONFIG_NAND_SPL. Now common code is used to initialize the
SDRAM by calling initdram() and to "copy/relocate" to SDRAM/OCM/etc.
Only *after* running from this location, nand_boot() is called.

Please note that the initsdram() call is now moved from nand_boot.c
to start.S. I experienced problems with some boards like Kilauea
(405EX), which don't have internal SRAM (OCM) and relocation needs to
be done to SDRAM before the NAND controller can get accessed. When
initdram() is called later on in nand_boot(), this can lead to problems
with variables in the bss sections like nand_ecc_pos[].

Signed-off-by: Stefan Roese <sr@denx.de>
Acked-by: Scott Wood <scottwood@freescale.com>

cpu/ppc4xx/start.S

@@ -187,6 +187,10 @@
  * at CFG_SDRAM_BASE and another 128MB cacheable instruction region covering
  * NOR flash at CFG_FLASH_BASE. Disable all cacheable data regions.
  */
+#if !defined(CFG_FLASH_BASE)
+/* If not already defined, set it to the "last" 128MByte region */
+# define CFG_FLASH_BASE		0xf8000000
+#endif
 #if !defined(CFG_ICACHE_SACR_VALUE)
 # define CFG_ICACHE_SACR_VALUE		\
 		(PPC_128MB_SACR_VALUE(CFG_SDRAM_BASE + (  0 << 20)) | \
@@ -486,97 +490,6 @@ rsttlb:	tlbwe	r0,r1,0x0000	/* Invalidate all entries (V=0)*/
 	/* Continue from 'normal' start */
 	/*----------------------------------------------------------------*/
 2:
-
-#if defined(CONFIG_NAND_SPL)
-#if defined(CONFIG_440EPX) || defined(CONFIG_440GRX) || \
-    defined(CONFIG_460EX) || defined(CONFIG_460GT)
-	/*
-	 * Enable internal SRAM (only on 440EPx/GRx, 440EP/GR have no OCM)
-	 */
-	lis	r2,0x7fff
-	ori	r2,r2,0xffff
-	mfdcr	r1,isram0_dpc
-	and	r1,r1,r2		/* Disable parity check */
-	mtdcr	isram0_dpc,r1
-	mfdcr	r1,isram0_pmeg
-	and	r1,r1,r2		/* Disable pwr mgmt */
-	mtdcr	isram0_pmeg,r1
-#if defined(CONFIG_460EX) || defined(CONFIG_460GT)
-	lis	r1,0x4000		/* BAS = 8000_0000 */
-	ori	r1,r1,0x4580		/* 16k */
-	mtdcr	isram0_sb0cr,r1
-#endif
-#endif
-#if defined(CONFIG_440EP)
-	/*
-	 * On 440EP with no internal SRAM, we setup SDRAM very early
-	 * and copy the NAND_SPL to SDRAM and jump to it
-	 */
-	/* Clear Dcache to use as RAM */
-	addis	r3,r0,CFG_INIT_RAM_ADDR@h
-	ori	r3,r3,CFG_INIT_RAM_ADDR@l
-	addis	r4,r0,CFG_INIT_RAM_END@h
-	ori	r4,r4,CFG_INIT_RAM_END@l
-	rlwinm. r5,r4,0,27,31
-	rlwinm	r5,r4,27,5,31
-	beq	..d_ran3
-	addi	r5,r5,0x0001
-..d_ran3:
-	mtctr	r5
-..d_ag3:
-	dcbz	r0,r3
-	addi	r3,r3,32
-	bdnz	..d_ag3
-	/*----------------------------------------------------------------*/
-	/* Setup the stack in internal SRAM */
-	/*----------------------------------------------------------------*/
-	lis	r1,CFG_INIT_RAM_ADDR@h
-	ori	r1,r1,CFG_INIT_SP_OFFSET@l
-	li	r0,0
-	stwu	r0,-4(r1)
-	stwu	r0,-4(r1)		/* Terminate call chain */
-
-	stwu	r1,-8(r1)		/* Save back chain and move SP */
-	lis	r0,RESET_VECTOR@h	/* Address of reset vector */
-	ori	r0,r0, RESET_VECTOR@l
-	stwu	r1,-8(r1)		/* Save back chain and move SP */
-	stw	r0,+12(r1)		/* Save return addr (underflow vect) */
-	sync
-	bl	early_sdram_init
-	sync
-#endif /* CONFIG_440EP */
-
-	/*
-	 * Copy SPL from cache into internal SRAM
-	 */
-	li	r4,(CFG_NAND_BOOT_SPL_SIZE >> 2) - 1
-	mtctr	r4
-	lis	r2,CFG_NAND_BOOT_SPL_SRC@h
-	ori	r2,r2,CFG_NAND_BOOT_SPL_SRC@l
-	lis	r3,CFG_NAND_BOOT_SPL_DST@h
-	ori	r3,r3,CFG_NAND_BOOT_SPL_DST@l
-spl_loop:
-	lwzu	r4,4(r2)
-	stwu	r4,4(r3)
-	bdnz	spl_loop
-
-	/*
-	 * Jump to code in RAM
-	 */
-	bl	00f
-00:	mflr	r10
-	lis	r3,(CFG_NAND_BOOT_SPL_SRC - CFG_NAND_BOOT_SPL_DST)@h
-	ori	r3,r3,(CFG_NAND_BOOT_SPL_SRC - CFG_NAND_BOOT_SPL_DST)@l
-	sub	r10,r10,r3
-	addi	r10,r10,28
-	mtlr	r10
-	blr
-
-start_ram:
-	sync
-	isync
-#endif /* CONFIG_NAND_SPL */
-
 	bl	3f
 	b	_start
 
@@ -831,7 +744,7 @@ _start:
 	stw	r0,+12(r1)		/* Save return addr (underflow vect) */
 
 #ifdef CONFIG_NAND_SPL
-	bl	nand_boot		/* will not return */
+	bl	nand_boot_common	/* will not return */
 #else
 	GET_GOT
 
@@ -992,12 +905,13 @@ _start:
 	ori	r4, r4, CFG_DCACHE_SACR_VALUE@l
 	mtdccr	r4
 
-#if !(defined(CFG_EBC_PB0AP) && defined(CFG_EBC_PB0CR)) || defined(CONFIG_405EX)
+#if !(defined(CFG_EBC_PB0AP) && defined(CFG_EBC_PB0CR))
 	/*----------------------------------------------------------------------- */
 	/* Tune the speed and size for flash CS0  */
 	/*----------------------------------------------------------------------- */
 	bl	ext_bus_cntlr_init
 #endif
+
 #if !(defined(CFG_INIT_DCACHE_CS) || defined(CFG_TEMP_STACK_OCM))
 	/*
 	 * For boards that don't have OCM and can't use the data cache
@@ -1085,38 +999,6 @@ _start:
 #endif /* CONFIG_405EZ */
 #endif
 
-#ifdef CONFIG_NAND_SPL
-	/*
-	 * Copy SPL from cache into internal SRAM
-	 */
-	li	r4,(CFG_NAND_BOOT_SPL_SIZE >> 2) - 1
-	mtctr	r4
-	lis	r2,CFG_NAND_BOOT_SPL_SRC@h
-	ori	r2,r2,CFG_NAND_BOOT_SPL_SRC@l
-	lis	r3,CFG_NAND_BOOT_SPL_DST@h
-	ori	r3,r3,CFG_NAND_BOOT_SPL_DST@l
-spl_loop:
-	lwzu	r4,4(r2)
-	stwu	r4,4(r3)
-	bdnz	spl_loop
-
-	/*
-	 * Jump to code in RAM
-	 */
-	bl	00f
-00:	mflr	r10
-	lis	r3,(CFG_NAND_BOOT_SPL_SRC - CFG_NAND_BOOT_SPL_DST)@h
-	ori	r3,r3,(CFG_NAND_BOOT_SPL_SRC - CFG_NAND_BOOT_SPL_DST)@l
-	sub	r10,r10,r3
-	addi	r10,r10,28
-	mtlr	r10
-	blr
-
-start_ram:
-	sync
-	isync
-#endif /* CONFIG_NAND_SPL */
-
 	/*----------------------------------------------------------------------- */
 	/* Setup temporary stack in DCACHE or OCM if needed for SDRAM SPD. */
 	/*----------------------------------------------------------------------- */
@@ -1243,7 +1125,7 @@ start_ram:
 	bl	sdram_init
 
 #ifdef CONFIG_NAND_SPL
-	bl	nand_boot		/* will not return */
+	bl	nand_boot_common	/* will not return */
 #else
 	GET_GOT			/* initialize GOT access			*/
 
@@ -2180,3 +2062,75 @@ pll_wait:
 	blr
 	function_epilog(mftlb1)
 #endif /* CONFIG_440 */
+
+#if defined(CONFIG_NAND_SPL)
+/*
+ * void nand_boot_relocate(dst, src, bytes)
+ *
+ * r3 = Destination address to copy code to (in SDRAM)
+ * r4 = Source address to copy code from
+ * r5 = size to copy in bytes
+ */
+nand_boot_relocate:
+	mr	r6,r3
+	mr	r7,r4
+	mflr	r8
+
+	/*
+	 * Copy SPL from icache into SDRAM
+	 */
+	subi	r3,r3,4
+	subi	r4,r4,4
+	srwi	r5,r5,2
+	mtctr	r5
+..spl_loop:
+	lwzu	r0,4(r4)
+	stwu	r0,4(r3)
+	bdnz	..spl_loop
+
+	/*
+	 * Calculate "corrected" link register, so that we "continue"
+	 * in execution in destination range
+	 */
+	sub	r3,r7,r6	/* r3 = src - dst */
+	sub	r8,r8,r3	/* r8 = link-reg - (src - dst) */
+	mtlr	r8
+	blr
+
+nand_boot_common:
+	/*
+	 * First initialize SDRAM. It has to be available *before* calling
+	 * nand_boot().
+	 */
+	lis	r3,CFG_SDRAM_BASE@h
+	ori	r3,r3,CFG_SDRAM_BASE@l
+	bl	initdram
+
+	/*
+	 * Now copy the 4k SPL code into SDRAM and continue execution
+	 * from there.
+	 */
+	lis	r3,CFG_NAND_BOOT_SPL_DST@h
+	ori	r3,r3,CFG_NAND_BOOT_SPL_DST@l
+	lis	r4,CFG_NAND_BOOT_SPL_SRC@h
+	ori	r4,r4,CFG_NAND_BOOT_SPL_SRC@l
+	lis	r5,CFG_NAND_BOOT_SPL_SIZE@h
+	ori	r5,r5,CFG_NAND_BOOT_SPL_SIZE@l
+	bl	nand_boot_relocate
+
+	/*
+	 * We're running from SDRAM now!!!
+	 *
+	 * It is necessary for 4xx systems to relocate from running at
+	 * the original location (0xfffffxxx) to somewhere else (SDRAM
+	 * preferably). This is because CS0 needs to be reconfigured for
+	 * NAND access. And we can't reconfigure this CS when currently
+	 * "running" from it.
+	 */
+
+	/*
+	 * Finally call nand_boot() to load main NAND U-Boot image from
+	 * NAND and jump to it.
+	 */
+	bl	nand_boot		/* will not return */
+#endif /* CONFIG_NAND_SPL */

nand_spl/nand_boot.c

@@ -221,19 +221,18 @@ static int nand_load(struct mtd_info *mtd, int offs, int uboot_size, uchar *dst)
 	return 0;
 }
 
+/*
+ * The main entry for NAND booting. It's necessary that SDRAM is already
+ * configured and available since this code loads the main U-Boot image
+ * from NAND into SDRAM and starts it from there.
+ */
 void nand_boot(void)
 {
-	ulong mem_size;
 	struct nand_chip nand_chip;
 	nand_info_t nand_info;
 	int ret;
 	void (*uboot)(void);
 
-	/*
-	 * Init sdram, so we have access to memory
-	 */
-	mem_size = initdram(0);
-
 	/*
 	 * Init board specific nand support
 	 */