diff options
Diffstat (limited to 'kernel/arch/cris/arch-v32/mach-fs/dram_init.S')
| -rw-r--r-- | kernel/arch/cris/arch-v32/mach-fs/dram_init.S | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/kernel/arch/cris/arch-v32/mach-fs/dram_init.S b/kernel/arch/cris/arch-v32/mach-fs/dram_init.S new file mode 100644 index 000000000..6fbad3365 --- /dev/null +++ b/kernel/arch/cris/arch-v32/mach-fs/dram_init.S @@ -0,0 +1,116 @@ +/* + * 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) 2000-2007 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 <hwregs/asm/reg_map_asm.h> +#include <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 + lapc _sdram_commands_start, $r2 + lapc _sdram_commands_end, $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: |