/*
 *
 * 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) 2000 Hewlett Packard (Paul Bame bame@puffin.external.hp.com)
 *
 */

#include <asm/pdc.h>
#include <asm/psw.h>
#include <asm/assembly.h>
#include <asm/asm-offsets.h>

#include <linux/linkage.h>

        .export real_stack
        .export real64_stack
        __PAGE_ALIGNED_BSS
real_stack:
real64_stack:
        .block  8192

#define N_SAVED_REGS 9
        .section        .bss
save_cr_space:
        .block  REG_SZ * N_SAVED_REGS
save_cr_end:


/************************ 32-bit real-mode calls ***********************/
/* This can be called in both narrow and wide kernels */

        .text

        /* unsigned long real32_call_asm(unsigned int *sp,
         *              unsigned int *arg0p,
         *              unsigned int iodc_fn)
         *      sp is value of stack pointer to adopt before calling PDC (virt)
         *      arg0p points to where saved arg values may be found
         *      iodc_fn is the IODC function to call
         */

ENTRY_CFI(real32_call_asm)
        STREG   %rp, -RP_OFFSET(%sp)    /* save RP */
#ifdef CONFIG_64BIT
        callee_save
        ldo     2*REG_SZ(%sp), %sp      /* room for a couple more saves */
        STREG   %r27, -1*REG_SZ(%sp)
        STREG   %r29, -2*REG_SZ(%sp)
#endif
        STREG   %sp, -REG_SZ(%arg0)     /* save SP on real-mode stack */
        copy    %arg0, %sp              /* adopt the real-mode SP */

        /* save iodc_fn */
        copy    %arg2, %r31

        /* load up the arg registers from the saved arg area */
        /* 32-bit calling convention passes first 4 args in registers */
        ldw     0(%arg1), %arg0         /* note overwriting arg0 */
        ldw     -8(%arg1), %arg2
        ldw     -12(%arg1), %arg3
        ldw     -4(%arg1), %arg1        /* obviously must do this one last! */

        tophys_r1  %sp

        b,l     rfi_virt2real,%r2
        nop

        b,l     save_control_regs,%r2           /* modifies r1, r2, r28 */
        nop

#ifdef CONFIG_64BIT
        rsm     PSW_SM_W, %r0           /* go narrow */
#endif

        load32  PA(ric_ret), %r2
        bv      0(%r31)
        nop
ric_ret:
#ifdef CONFIG_64BIT
        ssm     PSW_SM_W, %r0           /* go wide */
#endif
        /* restore CRs before going virtual in case we page fault */
        b,l     restore_control_regs, %r2       /* modifies r1, r2, r26 */
        nop

        b,l     rfi_real2virt,%r2
        nop

        tovirt_r1 %sp
        LDREG   -REG_SZ(%sp), %sp       /* restore SP */
#ifdef CONFIG_64BIT
        LDREG   -1*REG_SZ(%sp), %r27
        LDREG   -2*REG_SZ(%sp), %r29
        ldo     -2*REG_SZ(%sp), %sp
        callee_rest
#endif
        LDREG   -RP_OFFSET(%sp), %rp    /* restore RP */
        bv      0(%rp)
        nop
ENDPROC_CFI(real32_call_asm)


#  define PUSH_CR(r, where) mfctl r, %r1 ! STREG,ma %r1, REG_SZ(where)
#  define POP_CR(r, where) LDREG,mb -REG_SZ(where), %r1 ! mtctl %r1, r

        .text
ENTRY_CFI(save_control_regs)
        load32  PA(save_cr_space), %r28
        PUSH_CR(%cr24, %r28)
        PUSH_CR(%cr25, %r28)
        PUSH_CR(%cr26, %r28)
        PUSH_CR(%cr27, %r28)
        PUSH_CR(%cr28, %r28)
        PUSH_CR(%cr29, %r28)
        PUSH_CR(%cr30, %r28)
        PUSH_CR(%cr31, %r28)
        PUSH_CR(%cr15, %r28)
        bv 0(%r2)
        nop
ENDPROC_CFI(save_control_regs)

ENTRY_CFI(restore_control_regs)
        load32  PA(save_cr_end), %r26
        POP_CR(%cr15, %r26)
        POP_CR(%cr31, %r26)
        POP_CR(%cr30, %r26)
        POP_CR(%cr29, %r26)
        POP_CR(%cr28, %r26)
        POP_CR(%cr27, %r26)
        POP_CR(%cr26, %r26)
        POP_CR(%cr25, %r26)
        POP_CR(%cr24, %r26)
        bv 0(%r2)
        nop
ENDPROC_CFI(restore_control_regs)

/* rfi_virt2real() and rfi_real2virt() could perhaps be adapted for
 * more general-purpose use by the several places which need RFIs
 */
        .text
        .align 128
ENTRY_CFI(rfi_virt2real)
#if !defined(BOOTLOADER)
        /* switch to real mode... */
        rsm             PSW_SM_I,%r0
        load32          PA(rfi_v2r_1), %r1
        nop
        nop
        nop
        nop
        nop
        
        rsm             PSW_SM_Q,%r0  /* disable Q & I bits to load iia queue */
        mtctl           %r0, %cr17      /* Clear IIASQ tail */
        mtctl           %r0, %cr17      /* Clear IIASQ head */
        mtctl           %r1, %cr18      /* IIAOQ head */
        ldo             4(%r1), %r1
        mtctl           %r1, %cr18      /* IIAOQ tail */
        load32          REAL_MODE_PSW, %r1
        mtctl           %r1, %cr22
        rfi
        
        nop
        nop
        nop
        nop
        nop
        nop
        nop
        nop
rfi_v2r_1:
        tophys_r1 %r2
#endif /* defined(BOOTLOADER) */
        bv      0(%r2)
        nop
ENDPROC_CFI(rfi_virt2real)

        .text
        .align 128
ENTRY_CFI(rfi_real2virt)
#if !defined(BOOTLOADER)
        rsm             PSW_SM_I,%r0
        load32          (rfi_r2v_1), %r1
        nop
        nop
        nop
        nop
        nop
        
        rsm             PSW_SM_Q,%r0    /* disable Q bit to load iia queue */
        mtctl           %r0, %cr17      /* Clear IIASQ tail */
        mtctl           %r0, %cr17      /* Clear IIASQ head */
        mtctl           %r1, %cr18      /* IIAOQ head */
        ldo             4(%r1), %r1
        mtctl           %r1, %cr18      /* IIAOQ tail */
        load32          KERNEL_PSW, %r1
        mtctl           %r1, %cr22
        rfi
        
        nop
        nop
        nop
        nop
        nop
        nop
        nop
        nop
rfi_r2v_1:
        tovirt_r1 %r2
#endif /* defined(BOOTLOADER) */
        bv      0(%r2)
        nop
ENDPROC_CFI(rfi_real2virt)

#ifdef CONFIG_64BIT

/************************ 64-bit real-mode calls ***********************/
/* This is only usable in wide kernels right now and will probably stay so */
        .text
        /* unsigned long real64_call_asm(unsigned long *sp,
         *              unsigned long *arg0p,
         *              unsigned long fn)
         *      sp is value of stack pointer to adopt before calling PDC (virt)
         *      arg0p points to where saved arg values may be found
         *      iodc_fn is the IODC function to call
         */
ENTRY_CFI(real64_call_asm)
        std     %rp, -0x10(%sp)         /* save RP */
        std     %sp, -8(%arg0)          /* save SP on real-mode stack */
        copy    %arg0, %sp              /* adopt the real-mode SP */

        /* save fn */
        copy    %arg2, %r31

        /* load up the arg registers from the saved arg area */
        /* 32-bit calling convention passes first 4 args in registers */
        ldd     0*REG_SZ(%arg1), %arg0          /* note overwriting arg0 */
        ldd     2*REG_SZ(%arg1), %arg2
        ldd     3*REG_SZ(%arg1), %arg3
        ldd     4*REG_SZ(%arg1), %r22
        ldd     5*REG_SZ(%arg1), %r21
        ldd     6*REG_SZ(%arg1), %r20
        ldd     7*REG_SZ(%arg1), %r19
        ldd     1*REG_SZ(%arg1), %arg1          /* do this one last! */

        /* set up real-mode stack and real-mode ap */
        tophys_r1 %sp
        ldo     -16(%sp), %r29                  /* Reference param save area */

        b,l     rfi_virt2real,%r2
        nop

        b,l     save_control_regs,%r2           /* modifies r1, r2, r28 */
        nop

        load32  PA(r64_ret), %r2
        bv      0(%r31)
        nop
r64_ret:
        /* restore CRs before going virtual in case we page fault */
        b,l     restore_control_regs, %r2       /* modifies r1, r2, r26 */
        nop

        b,l     rfi_real2virt,%r2
        nop

        tovirt_r1 %sp
        ldd     -8(%sp), %sp            /* restore SP */
        ldd     -0x10(%sp), %rp         /* restore RP */
        bv      0(%rp)
        nop
ENDPROC_CFI(real64_call_asm)

#endif

        .text
        /* http://lists.parisc-linux.org/hypermail/parisc-linux/10916.html
        **      GCC 3.3 and later has a new function in libgcc.a for
        **      comparing function pointers.
        */
ENTRY_CFI(__canonicalize_funcptr_for_compare)
#ifdef CONFIG_64BIT
        bve (%r2)
#else
        bv %r0(%r2)
#endif
        copy %r26,%r28
ENDPROC_CFI(__canonicalize_funcptr_for_compare)