118 lines
3.5 KiB
ArmAsm
118 lines
3.5 KiB
ArmAsm
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/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* DRAM/SDRAM initialization - alter with care
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* This file is intended to be included from other assembler files
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*
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* Note: This file may not modify r8 or r9 because they are used to
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* carry information from the decompressor to the kernel
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*
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* Copyright (C) 2000-2007 Axis Communications AB
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*
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* Authors: Mikael Starvik <starvik@axis.com>
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*/
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/* Just to be certain the config file is included, we include it here
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* explicitly instead of depending on it being included in the file that
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* uses this code.
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*/
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#include <hwregs/asm/reg_map_asm.h>
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#include <hwregs/asm/bif_core_defs_asm.h>
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;; WARNING! The registers r8 and r9 are used as parameters carrying
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;; information from the decompressor (if the kernel was compressed).
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;; They should not be used in the code below.
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; Refer to BIF MDS for a description of SDRAM initialization
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; Bank configuration
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move.d REG_ADDR(bif_core, regi_bif_core, rw_sdram_cfg_grp0), $r0
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move.d CONFIG_ETRAX_SDRAM_GRP0_CONFIG, $r1
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move.d $r1, [$r0]
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move.d REG_ADDR(bif_core, regi_bif_core, rw_sdram_cfg_grp1), $r0
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move.d CONFIG_ETRAX_SDRAM_GRP1_CONFIG, $r1
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move.d $r1, [$r0]
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; Calculate value of mrs_data
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; CAS latency = 2 && bus_width = 32 => 0x40
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; CAS latency = 3 && bus_width = 32 => 0x60
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; CAS latency = 2 && bus_width = 16 => 0x20
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; CAS latency = 3 && bus_width = 16 => 0x30
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; Check if value is already supplied in kernel config
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move.d CONFIG_ETRAX_SDRAM_COMMAND, $r2
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bne _set_timing
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nop
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move.d 0x40, $r4 ; Assume 32 bits and CAS latency = 2
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move.d CONFIG_ETRAX_SDRAM_TIMING, $r1
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and.d 0x07, $r1 ; Get CAS latency
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cmpq 2, $r1 ; CL = 2 ?
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beq _bw_check
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nop
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move.d 0x60, $r4
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_bw_check:
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; Assume that group 0 width is equal to group 1. This assumption
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; is wrong for a group 1 only hardware (such as the grand old
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; StorPoint+).
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move.d CONFIG_ETRAX_SDRAM_GRP0_CONFIG, $r1
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and.d 0x200, $r1 ; DRAM width is bit 9
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beq _set_timing
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lslq 2, $r4 ; mrs_data starts at bit 2
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lsrq 1, $r4 ; 16 bits. Shift down value.
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; Set timing parameters (refresh off to avoid Guinness TR 83)
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_set_timing:
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move.d CONFIG_ETRAX_SDRAM_TIMING, $r1
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and.d ~(3 << reg_bif_core_rw_sdram_timing___ref___lsb), $r1
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move.d REG_ADDR(bif_core, regi_bif_core, rw_sdram_timing), $r0
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move.d $r1, [$r0]
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; Issue NOP command
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move.d REG_ADDR(bif_core, regi_bif_core, rw_sdram_cmd), $r5
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moveq regk_bif_core_nop, $r1
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move.d $r1, [$r5]
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; Wait 200us
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move.d 10000, $r2
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1: bne 1b
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subq 1, $r2
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; Issue initialization command sequence
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lapc _sdram_commands_start, $r2
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lapc _sdram_commands_end, $r3
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1: clear.d $r6
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move.b [$r2+], $r6 ; Load command
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or.d $r4, $r6 ; Add calculated mrs
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move.d $r6, [$r5] ; Write rw_sdram_cmd
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; Wait 80 ns between each command
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move.d 4000, $r7
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2: bne 2b
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subq 1, $r7
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cmp.d $r2, $r3 ; Last command?
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bne 1b
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nop
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; Start refresh
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move.d CONFIG_ETRAX_SDRAM_TIMING, $r1
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move.d REG_ADDR(bif_core, regi_bif_core, rw_sdram_timing), $r0
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move.d $r1, [$r0]
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; Initialization finished
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ba _sdram_commands_end
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nop
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_sdram_commands_start:
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.byte regk_bif_core_pre ; Precharge
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.byte regk_bif_core_ref ; refresh
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.byte regk_bif_core_ref ; refresh
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.byte regk_bif_core_ref ; refresh
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.byte regk_bif_core_ref ; refresh
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.byte regk_bif_core_ref ; refresh
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.byte regk_bif_core_ref ; refresh
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.byte regk_bif_core_ref ; refresh
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.byte regk_bif_core_ref ; refresh
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.byte regk_bif_core_mrs ; mrs
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_sdram_commands_end:
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