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/*
 * EFI call stub.
 *
 * Copyright (C) 1999-2001 Hewlett-Packard Co
 *      David Mosberger <davidm@hpl.hp.com>
 *
 * This stub allows us to make EFI calls in physical mode with interrupts
 * turned off.  We need this because we can't call SetVirtualMap() until
 * the kernel has booted far enough to allow allocation of struct vma_struct
 * entries (which we would need to map stuff with memory attributes other
 * than uncached or writeback...).  Since the GetTime() service gets called
 * earlier than that, we need to be able to make physical mode EFI calls from
 * the kernel.
 */

/*
 * PSR settings as per SAL spec (Chapter 8 in the "IA-64 System
 * Abstraction Layer Specification", revision 2.6e).  Note that
 * psr.dfl and psr.dfh MUST be cleared, despite what this manual says.
 * Otherwise, SAL dies whenever it's trying to do an IA-32 BIOS call
 * (the br.ia instruction fails unless psr.dfl and psr.dfh are
 * cleared).  Fortunately, SAL promises not to touch the floating
 * point regs, so at least we don't have to save f2-f127.
 */
#define PSR_BITS_TO_CLEAR                                               \
        (IA64_PSR_I | IA64_PSR_IT | IA64_PSR_DT | IA64_PSR_RT |         \
         IA64_PSR_DD | IA64_PSR_SS | IA64_PSR_RI | IA64_PSR_ED |        \
         IA64_PSR_DFL | IA64_PSR_DFH)

#define PSR_BITS_TO_SET                                                 \
        (IA64_PSR_BN)

#include <asm/processor.h>
#include <asm/asmmacro.h>

/*
 * Inputs:
 *      in0 = address of function descriptor of EFI routine to call
 *      in1..in7 = arguments to routine
 *
 * Outputs:
 *      r8 = EFI_STATUS returned by called function
 */

GLOBAL_ENTRY(efi_call_phys)
        .prologue ASM_UNW_PRLG_RP|ASM_UNW_PRLG_PFS, ASM_UNW_PRLG_GRSAVE(8)
        alloc loc1=ar.pfs,8,5,7,0
        ld8 r2=[in0],8                  // load EFI function's entry point
        mov loc0=rp
        .body
        ;;
        mov loc2=gp                     // save global pointer
        mov loc4=ar.rsc                 // save RSE configuration
        mov ar.rsc=0                    // put RSE in enforced lazy, LE mode
        ;;
        ld8 gp=[in0]                    // load EFI function's global pointer
        movl r16=PSR_BITS_TO_CLEAR
        mov loc3=psr                    // save processor status word
        movl r17=PSR_BITS_TO_SET
        ;;
        or loc3=loc3,r17
        mov b6=r2
        ;;
        andcm r16=loc3,r16              // get psr with IT, DT, and RT bits cleared
        br.call.sptk.many rp=ia64_switch_mode_phys
.ret0:  mov out4=in5
        mov out0=in1
        mov out1=in2
        mov out2=in3
        mov out3=in4
        mov out5=in6
        mov out6=in7
        br.call.sptk.many rp=b6         // call the EFI function
.ret1:  mov ar.rsc=0                    // put RSE in enforced lazy, LE mode
        mov r16=loc3
        br.call.sptk.many rp=ia64_switch_mode_virt // return to virtual mode
.ret2:  mov ar.rsc=loc4                 // restore RSE configuration
        mov ar.pfs=loc1
        mov rp=loc0
        mov gp=loc2
        br.ret.sptk.many rp
END(efi_call_phys)