ref: 39f18c9d88f52a22373790dec5721fa3521d3f00
dir: /sys/src/9/bcm/rebootcode.s/
/* * armv6 reboot code */ #include "arm.s" /* * Turn off MMU, then copy the new kernel to its correct location * in physical memory. Then jump to the start of the kernel. */ /* main(PADDR(entry), PADDR(code), size); */ TEXT main(SB), 1, $-4 MOVW $setR12(SB), R12 /* copy in arguments before stack gets unmapped */ MOVW R0, R8 /* entry point */ MOVW p2+4(FP), R9 /* source */ MOVW n+8(FP), R10 /* byte count */ /* SVC mode, interrupts disabled */ MOVW $(PsrDirq|PsrDfiq|PsrMsvc), R1 MOVW R1, CPSR /* prepare to turn off mmu */ BL cachesoff(SB) /* turn off mmu */ MRC CpSC, 0, R1, C(CpCONTROL), C(0), CpMainctl BIC $CpCmmu, R1 MCR CpSC, 0, R1, C(CpCONTROL), C(0), CpMainctl /* set up a tiny stack for local vars and memmove args */ MOVW R8, SP /* stack top just before kernel dest */ SUB $20, SP /* allocate stack frame */ /* copy the kernel to final destination */ MOVW R8, 16(SP) /* save dest (entry point) */ MOVW R8, R0 /* first arg is dest */ MOVW R9, 8(SP) /* push src */ MOVW R10, 12(SP) /* push size */ BL memmove(SB) MOVW 16(SP), R8 /* restore entry point */ /* jump to kernel physical entry point */ B (R8) B 0(PC) /* * turn the caches off, double map PHYSDRAM & KZERO, invalidate TLBs, revert * to tiny addresses. upon return, it will be safe to turn off the mmu. * clobbers R0-R2, and returns with SP invalid. */ TEXT cachesoff(SB), 1, $-4 /* write back and invalidate caches */ BARRIERS MOVW $0, R0 MCR CpSC, 0, R0, C(CpCACHE), C(CpCACHEwbi), CpCACHEall MCR CpSC, 0, R0, C(CpCACHE), C(CpCACHEinvi), CpCACHEall /* turn caches off */ MRC CpSC, 0, R1, C(CpCONTROL), C(0), CpMainctl BIC $(CpCdcache|CpCicache|CpCpredict), R1 MCR CpSC, 0, R1, C(CpCONTROL), C(0), CpMainctl /* invalidate stale TLBs before changing them */ BARRIERS MOVW $KZERO, R0 /* some valid virtual address */ MCR CpSC, 0, R0, C(CpTLB), C(CpTLBinvu), CpTLBinv BARRIERS /* from here on, R0 is base of physical memory */ MOVW $PHYSDRAM, R0 /* redo double map of first MiB PHYSDRAM = KZERO */ MOVW $(L1+L1X(PHYSDRAM)), R2 /* address of PHYSDRAM's PTE */ MOVW $PTEDRAM, R1 /* PTE bits */ ORR R0, R1 /* dram base */ MOVW R1, (R2) /* invalidate stale TLBs again */ BARRIERS MCR CpSC, 0, R0, C(CpTLB), C(CpTLBinvu), CpTLBinv BARRIERS /* relocate SB and return address to PHYSDRAM addressing */ MOVW $KSEGM, R1 /* clear segment bits */ BIC R1, R12 /* adjust SB */ ORR R0, R12 BIC R1, R14 /* adjust return address */ ORR R0, R14 RET