diff options
| author | Stefan Roese <sr@denx.de> | 2009-05-11 13:46:14 +0200 |
|---|---|---|
| committer | Wolfgang Denk <wd@denx.de> | 2009-06-12 20:39:47 +0200 |
| commit | d873133f2ba9bd613d5f6552c31cc70fb13f15d3 (patch) | |
| tree | 01a00655040050e5125ef15a24e01e605eb02ec6 /cpu/ppc4xx/start.S | |
| parent | 837db3d87f4bfe9261629fb4a1bb433506a3056a (diff) | |
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 <sr@denx.de>
Diffstat (limited to 'cpu/ppc4xx/start.S')
| -rw-r--r-- | cpu/ppc4xx/start.S | 33 |
1 files changed, 27 insertions, 6 deletions
diff --git a/cpu/ppc4xx/start.S b/cpu/ppc4xx/start.S index f2b8908b9..ac96fc28f 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 /*----------------------------------------------------------------*/ |