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/*
 * 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.
 *
 * Head.S contains the MIPS exception handler and startup code.
 *
 * Copyright (C) 1994, 1995 Waldorf Electronics
 * Written by Ralf Baechle and Andreas Busse
 * Copyright (C) 1994, 1995, 1996, 1997, 1998, 1999 Ralf Baechle
 * Copyright (C) 1999 Silicon Graphics, Inc.
 */
#include <linux/config.h>
#include <linux/init.h>
#include <asm/asm.h>
#include <asm/regdef.h>
#include <asm/processor.h>
#include <asm/mipsregs.h>
#include <asm/stackframe.h>
#include <asm/pgtable.h>
#include <asm/sn/addrs.h>
#include <asm/sn/sn0/hubni.h>
#include <asm/sn/klkernvars.h>

        .macro  ARC64_TWIDDLE_PC
#if defined(CONFIG_ARC64) || defined(CONFIG_MAPPED_KERNEL)
        /* We get launched at a XKPHYS address but the kernel is linked to
           run at a KSEG0 address, so jump there.  */
        PTR_LA  t0, \@f
        jr      t0
\@:
#endif
        .endm

#ifdef CONFIG_SGI_IP27
        /*
         * outputs the local nasid into res.  IP27 stuff.
         */
        .macro GET_NASID_ASM res
        dli     \res, LOCAL_HUB_ADDR(NI_STATUS_REV_ID)
        ld      \res, (\res)
        and     \res, NSRI_NODEID_MASK
        dsrl    \res, NSRI_NODEID_SHFT
        .endm
#endif /* CONFIG_SGI_IP27 */

        /*
         * inputs are the text nasid in t1, data nasid in t2.
         */
        .macro MAPPED_KERNEL_SETUP_TLB
#ifdef CONFIG_MAPPED_KERNEL
        /*
         * This needs to read the nasid - assume 0 for now.
         * Drop in 0xffffffffc0000000 in tlbhi, 0+VG in tlblo_0,
         * 0+DVG in tlblo_1.
         */
        dli     t0, 0xffffffffc0000000
        dmtc0   t0, CP0_ENTRYHI
        li      t0, 0x1c000             # Offset of text into node memory
        dsll    t1, NASID_SHFT          # Shift text nasid into place
        dsll    t2, NASID_SHFT          # Same for data nasid
        or      t1, t1, t0              # Physical load address of kernel text
        or      t2, t2, t0              # Physical load address of kernel data
        dsrl    t1, 12                  # 4K pfn
        dsrl    t2, 12                  # 4K pfn
        dsll    t1, 6                   # Get pfn into place
        dsll    t2, 6                   # Get pfn into place
        li      t0, ((_PAGE_GLOBAL|_PAGE_VALID| _CACHE_CACHABLE_COW) >> 6)
        or      t0, t0, t1
        mtc0    t0, CP0_ENTRYLO0        # physaddr, VG, cach exlwr
        li      t0, ((_PAGE_GLOBAL|_PAGE_VALID| _PAGE_DIRTY|_CACHE_CACHABLE_COW) >> 6)
        or      t0, t0, t2
        mtc0    t0, CP0_ENTRYLO1        # physaddr, DVG, cach exlwr
        li      t0, 0x1ffe000           # MAPPED_KERN_TLBMASK, TLBPGMASK_16M
        mtc0    t0, CP0_PAGEMASK
        li      t0, 0                   # KMAP_INX
        mtc0    t0, CP0_INDEX
        li      t0, 1
        mtc0    t0, CP0_WIRED
        tlbwi
#else
        mtc0    zero, CP0_WIRED
#endif
        .endm

        .text

EXPORT(stext)                                   # used for profiling
EXPORT(_stext)

        __INIT

NESTED(kernel_entry, 16, sp)                    # kernel entry point

        ori     sp, 0xf                         # align stack on 16 byte.
        xori    sp, 0xf

#ifdef CONFIG_SGI_IP27
        GET_NASID_ASM   t1
        move    t2, t1                          # text and data are here
        MAPPED_KERNEL_SETUP_TLB
#endif /* IP27 */

        ARC64_TWIDDLE_PC

        CLI                                     # disable interrupts

        /*
         * The firmware/bootloader passes argc/argp/envp
         * to us as arguments.  But clear bss first because
         * the romvec and other important info is stored there
         * by prom_init().
         */
        PTR_LA  t0, _edata
        sd      zero, (t0)
        PTR_LA  t1, (_end - 8)
1:
        daddiu  t0, 8
        sd      zero, (t0)
        bne     t0, t1, 1b

        PTR_LA  $28, init_task_union            # init current pointer
        daddiu  sp, $28, KERNEL_STACK_SIZE-32
        set_saved_sp    sp, t0, t1
        dsubu   sp, 4*SZREG                     # init stack pointer

        j       init_arch
        END(kernel_entry)

#ifdef CONFIG_SMP
/*
 * SMP slave cpus entry point.  Board specific code for bootstrap calls this
 * function after setting up the stack and gp registers.
 */
NESTED(smp_bootstrap, 16, sp)
#ifdef CONFIG_SGI_IP27
        GET_NASID_ASM   t1
        dli     t0, KLDIR_OFFSET + (KLI_KERN_VARS * KLDIR_ENT_SIZE) + \
                    KLDIR_OFF_POINTER + K0BASE
        dsll    t1, NASID_SHFT
        or      t0, t0, t1
        ld      t0, 0(t0)                       # t0 points to kern_vars struct
        lh      t1, KV_RO_NASID_OFFSET(t0)
        lh      t2, KV_RW_NASID_OFFSET(t0)
        MAPPED_KERNEL_SETUP_TLB
        ARC64_TWIDDLE_PC
#endif /* CONFIG_SGI_IP27 */

        CLI

        /*
         * For the moment set ST0_KU so the CPU will not spit fire when
         * executing 64-bit instructions.  The full initialization of the
         * CPU's status register is done later in per_cpu_trap_init().
         */
        mfc0    t0, CP0_STATUS
        or      t0, ST0_KX
        mtc0    t0, CP0_STATUS

        jal     start_secondary                 # XXX: IP27: cboot

        END(smp_bootstrap)
#endif /* CONFIG_SMP */

        __FINIT

        declare_saved_sp

        .macro  page name, order=0
        .globl  \name
\name:  .size   \name, (_PAGE_SIZE << \order)
        .org    . + (_PAGE_SIZE << \order)
        .type   \name, @object
        .endm

        .data
        .align  12

        page    swapper_pg_dir, _PGD_ORDER
        page    invalid_pmd_table, _PMD_ORDER
        page    invalid_pte_table, _PTE_ORDER
        page    kptbl, _PGD_ORDER
        .globl  ekptbl
        page    kpmdtbl, 0
ekptbl: