| /* |
| * arch/xtensa/kernel/head.S |
| * |
| * Xtensa Processor startup code. |
| * |
| * This file is subject to the terms and conditions of the GNU General Public |
| * License. See the file "COPYING" in the main directory of this archive |
| * for more details. |
| * |
| * Copyright (C) 2001 - 2008 Tensilica Inc. |
| * |
| * Chris Zankel <chris@zankel.net> |
| * Marc Gauthier <marc@tensilica.com, marc@alumni.uwaterloo.ca> |
| * Joe Taylor <joe@tensilica.com, joetylr@yahoo.com> |
| * Kevin Chea |
| */ |
| |
| #include <asm/processor.h> |
| #include <asm/page.h> |
| #include <asm/cacheasm.h> |
| #include <asm/initialize_mmu.h> |
| #include <asm/mxregs.h> |
| |
| #include <linux/init.h> |
| #include <linux/linkage.h> |
| |
| /* |
| * This module contains the entry code for kernel images. It performs the |
| * minimal setup needed to call the generic C routines. |
| * |
| * Prerequisites: |
| * |
| * - The kernel image has been loaded to the actual address where it was |
| * compiled to. |
| * - a2 contains either 0 or a pointer to a list of boot parameters. |
| * (see setup.c for more details) |
| * |
| */ |
| |
| /* |
| * _start |
| * |
| * The bootloader passes a pointer to a list of boot parameters in a2. |
| */ |
| |
| /* The first bytes of the kernel image must be an instruction, so we |
| * manually allocate and define the literal constant we need for a jx |
| * instruction. |
| */ |
| |
| __HEAD |
| .begin no-absolute-literals |
| |
| ENTRY(_start) |
| |
| /* Preserve the pointer to the boot parameter list in EXCSAVE_1 */ |
| wsr a2, excsave1 |
| _j _SetupOCD |
| |
| .align 4 |
| .literal_position |
| _SetupOCD: |
| /* |
| * Initialize WB, WS, and clear PS.EXCM (to allow loop instructions). |
| * Set Interrupt Level just below XCHAL_DEBUGLEVEL to allow |
| * xt-gdb to single step via DEBUG exceptions received directly |
| * by ocd. |
| */ |
| movi a1, 1 |
| movi a0, 0 |
| wsr a1, windowstart |
| wsr a0, windowbase |
| rsync |
| |
| movi a1, LOCKLEVEL |
| wsr a1, ps |
| rsync |
| |
| .global _SetupMMU |
| _SetupMMU: |
| Offset = _SetupMMU - _start |
| |
| #ifdef CONFIG_INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX |
| initialize_mmu |
| #if defined(CONFIG_MMU) && XCHAL_HAVE_PTP_MMU && XCHAL_HAVE_SPANNING_WAY |
| rsr a2, excsave1 |
| movi a3, XCHAL_KSEG_PADDR |
| bltu a2, a3, 1f |
| sub a2, a2, a3 |
| movi a3, XCHAL_KSEG_SIZE |
| bgeu a2, a3, 1f |
| movi a3, XCHAL_KSEG_CACHED_VADDR |
| add a2, a2, a3 |
| wsr a2, excsave1 |
| 1: |
| #endif |
| #endif |
| |
| movi a0, _startup |
| jx a0 |
| |
| ENDPROC(_start) |
| .end no-absolute-literals |
| |
| __REF |
| .literal_position |
| |
| ENTRY(_startup) |
| |
| /* Set a0 to 0 for the remaining initialization. */ |
| |
| movi a0, 0 |
| |
| #if XCHAL_HAVE_VECBASE |
| movi a2, VECBASE_VADDR |
| wsr a2, vecbase |
| #endif |
| |
| /* Clear debugging registers. */ |
| |
| #if XCHAL_HAVE_DEBUG |
| #if XCHAL_NUM_IBREAK > 0 |
| wsr a0, ibreakenable |
| #endif |
| wsr a0, icount |
| movi a1, 15 |
| wsr a0, icountlevel |
| |
| .set _index, 0 |
| .rept XCHAL_NUM_DBREAK |
| wsr a0, SREG_DBREAKC + _index |
| .set _index, _index + 1 |
| .endr |
| #endif |
| |
| /* Clear CCOUNT (not really necessary, but nice) */ |
| |
| wsr a0, ccount # not really necessary, but nice |
| |
| /* Disable zero-loops. */ |
| |
| #if XCHAL_HAVE_LOOPS |
| wsr a0, lcount |
| #endif |
| |
| /* Disable all timers. */ |
| |
| .set _index, 0 |
| .rept XCHAL_NUM_TIMERS |
| wsr a0, SREG_CCOMPARE + _index |
| .set _index, _index + 1 |
| .endr |
| |
| /* Interrupt initialization. */ |
| |
| movi a2, XCHAL_INTTYPE_MASK_SOFTWARE | XCHAL_INTTYPE_MASK_EXTERN_EDGE |
| wsr a0, intenable |
| wsr a2, intclear |
| |
| /* Disable coprocessors. */ |
| |
| #if XCHAL_HAVE_CP |
| wsr a0, cpenable |
| #endif |
| |
| /* Initialize the caches. |
| * a2, a3 are just working registers (clobbered). |
| */ |
| |
| #if XCHAL_DCACHE_LINE_LOCKABLE |
| ___unlock_dcache_all a2 a3 |
| #endif |
| |
| #if XCHAL_ICACHE_LINE_LOCKABLE |
| ___unlock_icache_all a2 a3 |
| #endif |
| |
| ___invalidate_dcache_all a2 a3 |
| ___invalidate_icache_all a2 a3 |
| |
| isync |
| |
| initialize_cacheattr |
| |
| #ifdef CONFIG_HAVE_SMP |
| movi a2, CCON # MX External Register to Configure Cache |
| movi a3, 1 |
| wer a3, a2 |
| #endif |
| |
| /* Setup stack and enable window exceptions (keep irqs disabled) */ |
| |
| movi a1, start_info |
| l32i a1, a1, 0 |
| |
| movi a2, PS_WOE_MASK | LOCKLEVEL |
| # WOE=1, INTLEVEL=LOCKLEVEL, UM=0 |
| wsr a2, ps # (enable reg-windows; progmode stack) |
| rsync |
| |
| #ifdef CONFIG_SMP |
| /* |
| * Notice that we assume with SMP that cores have PRID |
| * supported by the cores. |
| */ |
| rsr a2, prid |
| bnez a2, .Lboot_secondary |
| |
| #endif /* CONFIG_SMP */ |
| |
| /* Unpack data sections |
| * |
| * The linker script used to build the Linux kernel image |
| * creates a table located at __boot_reloc_table_start |
| * that contains the information what data needs to be unpacked. |
| * |
| * Uses a2-a7. |
| */ |
| |
| movi a2, __boot_reloc_table_start |
| movi a3, __boot_reloc_table_end |
| |
| 1: beq a2, a3, 3f # no more entries? |
| l32i a4, a2, 0 # start destination (in RAM) |
| l32i a5, a2, 4 # end destination (in RAM) |
| l32i a6, a2, 8 # start source (in ROM) |
| addi a2, a2, 12 # next entry |
| beq a4, a5, 1b # skip, empty entry |
| beq a4, a6, 1b # skip, source and dest. are the same |
| |
| 2: l32i a7, a6, 0 # load word |
| addi a6, a6, 4 |
| s32i a7, a4, 0 # store word |
| addi a4, a4, 4 |
| bltu a4, a5, 2b |
| j 1b |
| |
| 3: |
| /* All code and initialized data segments have been copied. |
| * Now clear the BSS segment. |
| */ |
| |
| movi a2, __bss_start # start of BSS |
| movi a3, __bss_stop # end of BSS |
| |
| __loopt a2, a3, a4, 2 |
| s32i a0, a2, 0 |
| __endla a2, a3, 4 |
| |
| #if XCHAL_DCACHE_IS_WRITEBACK |
| |
| /* After unpacking, flush the writeback cache to memory so the |
| * instructions/data are available. |
| */ |
| |
| ___flush_dcache_all a2 a3 |
| #endif |
| memw |
| isync |
| ___invalidate_icache_all a2 a3 |
| isync |
| |
| #ifdef CONFIG_XIP_KERNEL |
| /* Setup bootstrap CPU stack in XIP kernel */ |
| |
| movi a1, start_info |
| l32i a1, a1, 0 |
| #endif |
| |
| movi a6, 0 |
| xsr a6, excsave1 |
| |
| /* init_arch kick-starts the linux kernel */ |
| |
| call4 init_arch |
| call4 start_kernel |
| |
| should_never_return: |
| j should_never_return |
| |
| #ifdef CONFIG_SMP |
| .Lboot_secondary: |
| |
| movi a2, cpu_start_ccount |
| 1: |
| memw |
| l32i a3, a2, 0 |
| beqi a3, 0, 1b |
| movi a3, 0 |
| s32i a3, a2, 0 |
| 1: |
| memw |
| l32i a3, a2, 0 |
| beqi a3, 0, 1b |
| wsr a3, ccount |
| movi a3, 0 |
| s32i a3, a2, 0 |
| memw |
| |
| movi a6, 0 |
| wsr a6, excsave1 |
| |
| call4 secondary_start_kernel |
| j should_never_return |
| |
| #endif /* CONFIG_SMP */ |
| |
| ENDPROC(_startup) |
| |
| #ifdef CONFIG_HOTPLUG_CPU |
| |
| ENTRY(cpu_restart) |
| |
| #if XCHAL_DCACHE_IS_WRITEBACK |
| ___flush_invalidate_dcache_all a2 a3 |
| #else |
| ___invalidate_dcache_all a2 a3 |
| #endif |
| memw |
| movi a2, CCON # MX External Register to Configure Cache |
| movi a3, 0 |
| wer a3, a2 |
| extw |
| |
| rsr a0, prid |
| neg a2, a0 |
| movi a3, cpu_start_id |
| memw |
| s32i a2, a3, 0 |
| #if XCHAL_DCACHE_IS_WRITEBACK |
| dhwbi a3, 0 |
| #endif |
| 1: |
| memw |
| l32i a2, a3, 0 |
| dhi a3, 0 |
| bne a2, a0, 1b |
| |
| /* |
| * Initialize WB, WS, and clear PS.EXCM (to allow loop instructions). |
| * Set Interrupt Level just below XCHAL_DEBUGLEVEL to allow |
| * xt-gdb to single step via DEBUG exceptions received directly |
| * by ocd. |
| */ |
| movi a1, 1 |
| movi a0, 0 |
| wsr a1, windowstart |
| wsr a0, windowbase |
| rsync |
| |
| movi a1, LOCKLEVEL |
| wsr a1, ps |
| rsync |
| |
| j _startup |
| |
| ENDPROC(cpu_restart) |
| |
| #endif /* CONFIG_HOTPLUG_CPU */ |
| |
| /* |
| * DATA section |
| */ |
| |
| __REFDATA |
| .align 4 |
| ENTRY(start_info) |
| .long init_thread_union + KERNEL_STACK_SIZE |
| |
| /* |
| * BSS section |
| */ |
| |
| __PAGE_ALIGNED_BSS |
| #ifdef CONFIG_MMU |
| ENTRY(swapper_pg_dir) |
| .fill PAGE_SIZE, 1, 0 |
| END(swapper_pg_dir) |
| #endif |
| ENTRY(empty_zero_page) |
| .fill PAGE_SIZE, 1, 0 |
| END(empty_zero_page) |
