From d873133f2ba9bd613d5f6552c31cc70fb13f15d3 Mon Sep 17 00:00:00 2001 From: Stefan Roese Date: Mon, 11 May 2009 13:46:14 +0200 Subject: ppc4xx: Add Sequoia RAM-booting target This patch adds another build target for the AMCC Sequoia PPC440EPx eval board. This RAM-booting version is targeted for boards without NOR FLASH (NAND booting) which need a possibility to initially program their NAND FLASH. Using a JTAG debugger (e.g. BDI2000/3000) configured to setup the SDRAM, this debugger can load this RAM- booting image to the target address in SDRAM (in this case 0x1000000) and start it there. Then U-Boot's standard NAND commands can be used to program the NAND FLASH (e.g. "nand write ..."). Here the commands to load and start this image from the BDI2000: 440EPX>reset halt 440EPX>load 0x1000000 /tftpboot/sequoia/u-boot.bin 440EPX>go 0x1000000 Please note that this image automatically scans for an already initialized SDRAM TLB (detected by EPN=0). This TLB will not be cleared. This TLB doesn't need to be TLB #0, this RAM-booting version will detect it and preserve it. So booting via BDI2000 will work and booting with a complete different TLB init via U-Boot works as well. Signed-off-by: Stefan Roese --- cpu/ppc4xx/start.S | 33 +++++++++++++++++++++++++++------ 1 file changed, 27 insertions(+), 6 deletions(-) (limited to 'cpu') diff --git a/cpu/ppc4xx/start.S b/cpu/ppc4xx/start.S index f2b8908..ac96fc2 100644 --- a/cpu/ppc4xx/start.S +++ b/cpu/ppc4xx/start.S @@ -257,6 +257,14 @@ bl board_init_f #endif +#if defined(CONFIG_SYS_RAMBOOT) + /* + * 4xx RAM-booting U-Boot image is started from offset 0 + */ + .text + bl _start_440 +#endif + /* * 440 Startup -- on reset only the top 4k of the effective * address space is mapped in by an entry in the instruction @@ -444,10 +452,17 @@ skip_debug_init: addis r0,0,0x0000 li r1,0x003f /* 64 TLB entries */ mtctr r1 -rsttlb: tlbwe r0,r1,0x0000 /* Invalidate all entries (V=0)*/ - tlbwe r0,r1,0x0001 - tlbwe r0,r1,0x0002 - subi r1,r1,0x0001 + li r4,0 /* Start with TLB #0 */ +rsttlb: +#ifdef CONFIG_SYS_RAMBOOT + tlbre r3,r4,0 /* Read contents from TLB word #0 to get EPN */ + rlwinm. r3,r3,0,0xfffffc00 /* Mask EPN */ + beq tlbnxt /* Skip EPN=0 TLB, this is the SDRAM TLB */ +#endif + tlbwe r0,r4,0 /* Invalidate all entries (V=0)*/ + tlbwe r0,r4,1 + tlbwe r0,r4,2 +tlbnxt: addi r4,r4,1 /* Next TLB */ bdnz rsttlb /*----------------------------------------------------------------*/ @@ -476,7 +491,13 @@ rsttlb: tlbwe r0,r1,0x0000 /* Invalidate all entries (V=0)*/ li r4,0 /* TLB # */ addi r5,r5,-4 -1: lwzu r0,4(r5) +1: +#ifdef CONFIG_SYS_RAMBOOT + tlbre r3,r4,0 /* Read contents from TLB word #0 */ + rlwinm. r3,r3,0,0x00000200 /* Mask V (valid) bit */ + bne tlbnx2 /* Skip V=1 TLB, this is the SDRAM TLB */ +#endif + lwzu r0,4(r5) cmpwi r0,0 beq 2f /* 0 marks end */ lwzu r1,4(r5) @@ -484,7 +505,7 @@ rsttlb: tlbwe r0,r1,0x0000 /* Invalidate all entries (V=0)*/ tlbwe r0,r4,0 /* TLB Word 0 */ tlbwe r1,r4,1 /* TLB Word 1 */ tlbwe r2,r4,2 /* TLB Word 2 */ - addi r4,r4,1 /* Next TLB */ +tlbnx2: addi r4,r4,1 /* Next TLB */ bdnz 1b /*----------------------------------------------------------------*/ -- cgit v1.1