| /* $Id: dram_init.S,v 1.4 2005/04/24 18:48:32 starvik Exp $ |
| * |
| * DRAM/SDRAM initialization - alter with care |
| * This file is intended to be included from other assembler files |
| * |
| * Note: This file may not modify r8 or r9 because they are used to |
| * carry information from the decompresser to the kernel |
| * |
| * Copyright (C) 2000-2003 Axis Communications AB |
| * |
| * Authors: Mikael Starvik (starvik@axis.com) |
| */ |
| |
| /* Just to be certain the config file is included, we include it here |
| * explicitely instead of depending on it being included in the file that |
| * uses this code. |
| */ |
| |
| #include <asm/arch/hwregs/asm/reg_map_asm.h> |
| #include <asm/arch/hwregs/asm/bif_core_defs_asm.h> |
| |
| ;; WARNING! The registers r8 and r9 are used as parameters carrying |
| ;; information from the decompressor (if the kernel was compressed). |
| ;; They should not be used in the code below. |
| |
| ; Refer to BIF MDS for a description of SDRAM initialization |
| |
| ; Bank configuration |
| move.d REG_ADDR(bif_core, regi_bif_core, rw_sdram_cfg_grp0), $r0 |
| move.d CONFIG_ETRAX_SDRAM_GRP0_CONFIG, $r1 |
| move.d $r1, [$r0] |
| move.d REG_ADDR(bif_core, regi_bif_core, rw_sdram_cfg_grp1), $r0 |
| move.d CONFIG_ETRAX_SDRAM_GRP1_CONFIG, $r1 |
| move.d $r1, [$r0] |
| |
| ; Calculate value of mrs_data |
| ; CAS latency = 2 && bus_width = 32 => 0x40 |
| ; CAS latency = 3 && bus_width = 32 => 0x60 |
| ; CAS latency = 2 && bus_width = 16 => 0x20 |
| ; CAS latency = 3 && bus_width = 16 => 0x30 |
| |
| ; Check if value is already supplied in kernel config |
| move.d CONFIG_ETRAX_SDRAM_COMMAND, $r2 |
| bne _set_timing |
| nop |
| |
| move.d 0x40, $r4 ; Assume 32 bits and CAS latency = 2 |
| move.d CONFIG_ETRAX_SDRAM_TIMING, $r1 |
| and.d 0x07, $r1 ; Get CAS latency |
| cmpq 2, $r1 ; CL = 2 ? |
| beq _bw_check |
| nop |
| move.d 0x60, $r4 |
| |
| _bw_check: |
| ; Assume that group 0 width is equal to group 1. This assumption |
| ; is wrong for a group 1 only hardware (such as the grand old |
| ; StorPoint+). |
| move.d CONFIG_ETRAX_SDRAM_GRP0_CONFIG, $r1 |
| and.d 0x200, $r1 ; DRAM width is bit 9 |
| beq _set_timing |
| lslq 2, $r4 ; mrs_data starts at bit 2 |
| lsrq 1, $r4 ; 16 bits. Shift down value. |
| |
| ; Set timing parameters (refresh off to avoid Guinness TR 83) |
| _set_timing: |
| move.d CONFIG_ETRAX_SDRAM_TIMING, $r1 |
| and.d ~(3 << reg_bif_core_rw_sdram_timing___ref___lsb), $r1 |
| move.d REG_ADDR(bif_core, regi_bif_core, rw_sdram_timing), $r0 |
| move.d $r1, [$r0] |
| |
| ; Issue NOP command |
| move.d REG_ADDR(bif_core, regi_bif_core, rw_sdram_cmd), $r5 |
| moveq regk_bif_core_nop, $r1 |
| move.d $r1, [$r5] |
| |
| ; Wait 200us |
| move.d 10000, $r2 |
| 1: bne 1b |
| subq 1, $r2 |
| |
| ; Issue initialization command sequence |
| move.d _sdram_commands_start, $r2 |
| and.d 0x000fffff, $r2 ; Make sure commands are read from flash |
| move.d _sdram_commands_end, $r3 |
| and.d 0x000fffff, $r3 |
| 1: clear.d $r6 |
| move.b [$r2+], $r6 ; Load command |
| or.d $r4, $r6 ; Add calculated mrs |
| move.d $r6, [$r5] ; Write rw_sdram_cmd |
| ; Wait 80 ns between each command |
| move.d 4000, $r7 |
| 2: bne 2b |
| subq 1, $r7 |
| cmp.d $r2, $r3 ; Last command? |
| bne 1b |
| nop |
| |
| ; Start refresh |
| move.d CONFIG_ETRAX_SDRAM_TIMING, $r1 |
| move.d REG_ADDR(bif_core, regi_bif_core, rw_sdram_timing), $r0 |
| move.d $r1, [$r0] |
| |
| ; Initialization finished |
| ba _sdram_commands_end |
| nop |
| |
| _sdram_commands_start: |
| .byte regk_bif_core_pre ; Precharge |
| .byte regk_bif_core_ref ; refresh |
| .byte regk_bif_core_ref ; refresh |
| .byte regk_bif_core_ref ; refresh |
| .byte regk_bif_core_ref ; refresh |
| .byte regk_bif_core_ref ; refresh |
| .byte regk_bif_core_ref ; refresh |
| .byte regk_bif_core_ref ; refresh |
| .byte regk_bif_core_ref ; refresh |
| .byte regk_bif_core_mrs ; mrs |
| _sdram_commands_end: |
