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https://github.com/brain-hackers/u-boot-brain
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![Masahiro Yamada](/assets/img/avatar_default.png)
Cache coherency for SMP is cared by Linux. In U-Boot, the secondary CPU(s) are just sleeping. Nothing in memory is shared with the primary CPU. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
177 lines
4.8 KiB
ArmAsm
177 lines
4.8 KiB
ArmAsm
/*
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* Copyright (C) 2012-2015 Masahiro Yamada <yamada.masahiro@socionext.com>
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*
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* SPDX-License-Identifier: GPL-2.0+
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*/
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#include <config.h>
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#include <linux/linkage.h>
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#include <linux/sizes.h>
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#include <asm/system.h>
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#include <mach/led.h>
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#include <mach/arm-mpcore.h>
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#include <mach/sbc-regs.h>
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#include <mach/ssc-regs.h>
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ENTRY(lowlevel_init)
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mov r8, lr @ persevere link reg across call
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/*
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* The UniPhier Boot ROM loads SPL code to the L2 cache.
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* But CPUs can only do instruction fetch now because start.S has
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* cleared C and M bits.
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* First we need to turn on MMU and Dcache again to get back
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* data access to L2.
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*/
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mrc p15, 0, r0, c1, c0, 0 @ SCTLR (System Control Register)
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orr r0, r0, #(CR_C | CR_M) @ enable MMU and Dcache
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mcr p15, 0, r0, c1, c0, 0
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#ifdef CONFIG_DEBUG_LL
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bl setup_lowlevel_debug
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#endif
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/*
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* Now we are using the page table embedded in the Boot ROM.
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* It is not handy since it is not a straight mapped table for sLD3.
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* What we need to do next is to switch over to the page table in SPL.
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*/
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ldr r3, =init_page_table @ page table must be 16KB aligned
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/* Disable MMU and Dcache before switching Page Table */
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mrc p15, 0, r0, c1, c0, 0 @ SCTLR (System Control Register)
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bic r0, r0, #(CR_C | CR_M) @ disable MMU and Dcache
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mcr p15, 0, r0, c1, c0, 0
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bl enable_mmu
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#ifdef CONFIG_UNIPHIER_SMP
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secondary_startup:
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/*
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* Entry point for secondary CPUs
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*
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* The Boot ROM has already enabled MMU for the secondary CPUs as well
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* as for the primary one. The MMU table embedded in the Boot ROM
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* prohibits the DRAM access, so it is impossible to bring the
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* secondary CPUs into DRAM directly. They must jump here into SPL,
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* which is run on L2 cache.
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*
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* Boot Sequence
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* [primary CPU] [secondary CPUs]
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* start from Boot ROM start from Boot ROM
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* jump to SPL sleep in Boot ROM
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* kick secondaries ---(sev)---> jump to SPL
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* jump to U-Boot main sleep in SPL
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* jump to Linux
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* kick secondaries ---(sev)---> jump to Linux
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*/
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/* branch by CPU ID */
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mrc p15, 0, r0, c0, c0, 5 @ MPIDR (Multiprocessor Affinity Register)
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and r0, r0, #0x3
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cmp r0, #0x0
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beq primary_cpu
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/* only for secondary CPUs */
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ldr r1, =ROM_BOOT_ROMRSV2 @ The last data access to L2 cache
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mrc p15, 0, r0, c1, c0, 0 @ SCTLR (System Control Register)
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orr r0, r0, #CR_I @ Enable ICache
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bic r0, r0, #(CR_C | CR_M) @ MMU and Dcache must be disabled
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mcr p15, 0, r0, c1, c0, 0 @ before jumping to Linux
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mov r0, #0
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str r0, [r1]
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b 1f
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/*
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* L2 cache is shared among all the CPUs and it might be disabled by
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* the primary one. Before that, the following 5 lines must be cached
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* on the Icaches of the secondary CPUs.
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*/
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0: wfe @ kicked by Linux
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1: ldr r0, [r1]
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cmp r0, #0
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bxne r0 @ r0: Linux entry for secondary CPUs
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b 0b
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primary_cpu:
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ldr r1, =ROM_BOOT_ROMRSV2
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ldr r0, =secondary_startup
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str r0, [r1]
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ldr r0, [r1] @ make sure str is complete before sev
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sev @ kick the secondary CPU
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#endif
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bl setup_init_ram @ RAM area for temporary stack pointer
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mov lr, r8 @ restore link
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mov pc, lr @ back to my caller
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ENDPROC(lowlevel_init)
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ENTRY(enable_mmu)
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mrc p15, 0, r0, c2, c0, 2 @ TTBCR (Translation Table Base Control Register)
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bic r0, r0, #0x37
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orr r0, r0, #0x20 @ disable TTBR1
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mcr p15, 0, r0, c2, c0, 2
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orr r0, r3, #0x8 @ Outer Cacheability for table walks: WBWA
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mcr p15, 0, r0, c2, c0, 0 @ TTBR0
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mov r0, #0
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mcr p15, 0, r0, c8, c7, 0 @ invalidate TLBs
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mov r0, #-1 @ manager for all domains (No permission check)
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mcr p15, 0, r0, c3, c0, 0 @ DACR (Domain Access Control Register)
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dsb
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isb
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/*
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* MMU on:
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* TLBs was already invalidated in "../start.S"
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* So, we don't need to invalidate it here.
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*/
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mrc p15, 0, r0, c1, c0, 0 @ SCTLR (System Control Register)
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orr r0, r0, #(CR_C | CR_M) @ MMU and Dcache enable
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mcr p15, 0, r0, c1, c0, 0
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mov pc, lr
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ENDPROC(enable_mmu)
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/*
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* For PH1-Pro4 or older SoCs, the size of WAY is 32KB.
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* It is large enough for tmp RAM.
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*/
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#define BOOT_RAM_SIZE (SZ_32K)
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#define BOOT_WAY_BITS (0x00000100) /* way 8 */
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ENTRY(setup_init_ram)
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/*
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* Touch to zero for the boot way
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*/
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0:
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/*
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* set SSCOQM, SSCOQAD, SSCOQSZ, SSCOQWN in this order
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*/
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ldr r0, = 0x00408006 @ touch to zero with address range
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ldr r1, = SSCOQM
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str r0, [r1]
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ldr r0, = (CONFIG_SPL_STACK - BOOT_RAM_SIZE) @ base address
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ldr r1, = SSCOQAD
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str r0, [r1]
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ldr r0, = BOOT_RAM_SIZE
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ldr r1, = SSCOQSZ
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str r0, [r1]
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ldr r0, = BOOT_WAY_BITS
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ldr r1, = SSCOQWN
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str r0, [r1]
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ldr r1, = SSCOPPQSEF
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ldr r0, [r1]
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cmp r0, #0 @ check if the command is successfully set
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bne 0b @ try again if an error occurs
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ldr r1, = SSCOLPQS
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1:
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ldr r0, [r1]
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cmp r0, #0x4
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bne 1b @ wait until the operation is completed
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str r0, [r1] @ clear the complete notification flag
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mov pc, lr
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ENDPROC(setup_init_ram)
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