Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*
 *  FPU support code, moved here from head.S so that it can be used
 *  by chips which use other head-whatever.S files.
 *
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *    Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
 *    Copyright (C) 1996 Paul Mackerras.
 *    Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 *
 */

#include <asm/reg.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/pgtable.h>
#include <asm/cputable.h>
#include <asm/cache.h>
#include <asm/thread_info.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>

/*
 * This task wants to use the FPU now.
 * On UP, disable FP for the task which had the FPU previously,
 * and save its floating-point registers in its thread_struct.
 * Load up this task's FP registers from its thread_struct,
 * enable the FPU for the current task and return to the task.
 */
_GLOBAL(load_up_fpu)
        mfmsr   r5
        ori     r5,r5,MSR_FP
        SYNC
        MTMSRD(r5)                      /* enable use of fpu now */
        isync
/*
 * For SMP, we don't do lazy FPU switching because it just gets too
 * horrendously complex, especially when a task switches from one CPU
 * to another.  Instead we call giveup_fpu in switch_to.
 */
#ifndef CONFIG_SMP
        LOAD_REG_ADDRBASE(r3, last_task_used_math)
        toreal(r3)
        PPC_LL  r4,ADDROFF(last_task_used_math)(r3)
        PPC_LCMPI       0,r4,0
        beq     1f
        toreal(r4)
        addi    r4,r4,THREAD            /* want last_task_used_math->thread */
        SAVE_32FPRS(0, r4)
        mffs    fr0
        stfd    fr0,THREAD_FPSCR(r4)
        PPC_LL  r5,PT_REGS(r4)
        toreal(r5)
        PPC_LL  r4,_MSR-STACK_FRAME_OVERHEAD(r5)
        li      r10,MSR_FP|MSR_FE0|MSR_FE1
        andc    r4,r4,r10               /* disable FP for previous task */
        PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#endif /* CONFIG_SMP */
        /* enable use of FP after return */
#ifdef CONFIG_PPC32
        mfspr   r5,SPRN_SPRG3           /* current task's THREAD (phys) */
        lwz     r4,THREAD_FPEXC_MODE(r5)
        ori     r9,r9,MSR_FP            /* enable FP for current */
        or      r9,r9,r4
#else
        ld      r4,PACACURRENT(r13)
        addi    r5,r4,THREAD            /* Get THREAD */
        lwz     r4,THREAD_FPEXC_MODE(r5)
        ori     r12,r12,MSR_FP
        or      r12,r12,r4
        std     r12,_MSR(r1)
#endif
        lfd     fr0,THREAD_FPSCR(r5)
        MTFSF_L(fr0)
        REST_32FPRS(0, r5)
#ifndef CONFIG_SMP
        subi    r4,r5,THREAD
        fromreal(r4)
        PPC_STL r4,ADDROFF(last_task_used_math)(r3)
#endif /* CONFIG_SMP */
        /* restore registers and return */
        /* we haven't used ctr or xer or lr */
        b       fast_exception_return

/*
 * giveup_fpu(tsk)
 * Disable FP for the task given as the argument,
 * and save the floating-point registers in its thread_struct.
 * Enables the FPU for use in the kernel on return.
 */
_GLOBAL(giveup_fpu)
        mfmsr   r5
        ori     r5,r5,MSR_FP
        SYNC_601
        ISYNC_601
        MTMSRD(r5)                      /* enable use of fpu now */
        SYNC_601
        isync
        PPC_LCMPI       0,r3,0
        beqlr-                          /* if no previous owner, done */
        addi    r3,r3,THREAD            /* want THREAD of task */
        PPC_LL  r5,PT_REGS(r3)
        PPC_LCMPI       0,r5,0
        SAVE_32FPRS(0, r3)
        mffs    fr0
        stfd    fr0,THREAD_FPSCR(r3)
        beq     1f
        PPC_LL  r4,_MSR-STACK_FRAME_OVERHEAD(r5)
        li      r3,MSR_FP|MSR_FE0|MSR_FE1
        andc    r4,r4,r3                /* disable FP for previous task */
        PPC_STL r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#ifndef CONFIG_SMP
        li      r5,0
        LOAD_REG_ADDRBASE(r4,last_task_used_math)
        PPC_STL r5,ADDROFF(last_task_used_math)(r4)
#endif /* CONFIG_SMP */
        blr

/*
 * These are used in the alignment trap handler when emulating
 * single-precision loads and stores.
 * We restore and save the fpscr so the task gets the same result
 * and exceptions as if the cpu had performed the load or store.
 */

_GLOBAL(cvt_fd)
        lfd     0,THREAD_FPSCR(r5)      /* load up fpscr value */
        MTFSF_L(0)
        lfs     0,0(r3)
        stfd    0,0(r4)
        mffs    0
        stfd    0,THREAD_FPSCR(r5)      /* save new fpscr value */
        blr

_GLOBAL(cvt_df)
        lfd     0,THREAD_FPSCR(r5)      /* load up fpscr value */
        MTFSF_L(0)
        lfd     0,0(r3)
        stfs    0,0(r4)
        mffs    0
        stfd    0,THREAD_FPSCR(r5)      /* save new fpscr value */
        blr