/*
 * Software emulation of some PPC instructions for the 8xx core.
 *
 * Copyright (C) 1998 Dan Malek (dmalek@jlc.net)
 *
 * Software floating emuation for the MPC8xx processor.  I did this mostly
 * because it was easier than trying to get the libraries compiled for
 * software floating point.  The goal is still to get the libraries done,
 * but I lost patience and needed some hacks to at least get init and
 * shells running.  The first problem is the setjmp/longjmp that save
 * and restore the floating point registers.
 *
 * For this emulation, our working registers are found on the register
 * save area.
 */

#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/interrupt.h>

#include <asm/pgtable.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>

/* Eventually we may need a look-up table, but this works for now.
*/
#define LFS     48
#define LFD     50
#define LFDU    51
#define STFD    54
#define STFDU   55
#define FMR     63

void print_8xx_pte(struct mm_struct *mm, unsigned long addr)
{
        pgd_t *pgd;
        pmd_t *pmd;
        pte_t *pte;

        printk(" pte @ 0x%8lx: ", addr);
        pgd = pgd_offset(mm, addr & PAGE_MASK);
        if (pgd) {
                pmd = pmd_offset(pud_offset(pgd, addr & PAGE_MASK),
                                 addr & PAGE_MASK);
                if (pmd && pmd_present(*pmd)) {
                        pte = pte_offset_kernel(pmd, addr & PAGE_MASK);
                        if (pte) {
                                printk(" (0x%08lx)->(0x%08lx)->0x%08lx\n",
                                        (long)pgd, (long)pte, (long)pte_val(*pte));
#define pp ((long)pte_val(*pte))
                                printk(" RPN: %05lx PP: %lx SPS: %lx SH: %lx "
                                       "CI: %lx v: %lx\n",
                                       pp>>12,    /* rpn */
                                       (pp>>10)&3, /* pp */
                                       (pp>>3)&1, /* small */
                                       (pp>>2)&1, /* shared */
                                       (pp>>1)&1, /* cache inhibit */
                                       pp&1       /* valid */
                                       );
#undef pp
                        }
                        else {
                                printk("no pte\n");
                        }
                }
                else {
                        printk("no pmd\n");
                }
        }
        else {
                printk("no pgd\n");
        }
}

int get_8xx_pte(struct mm_struct *mm, unsigned long addr)
{
        pgd_t *pgd;
        pmd_t *pmd;
        pte_t *pte;
        int retval = 0;

        pgd = pgd_offset(mm, addr & PAGE_MASK);
        if (pgd) {
                pmd = pmd_offset(pud_offset(pgd, addr & PAGE_MASK),
                                 addr & PAGE_MASK);
                if (pmd && pmd_present(*pmd)) {
                        pte = pte_offset_kernel(pmd, addr & PAGE_MASK);
                        if (pte) {
                                retval = (int)pte_val(*pte);
                        }
                }
        }
        return retval;
}

/*
 * We return 0 on success, 1 on unimplemented instruction, and EFAULT
 * if a load/store faulted.
 */
int Soft_emulate_8xx(struct pt_regs *regs)
{
        u32 inst, instword;
        u32 flreg, idxreg, disp;
        int retval;
        s16 sdisp;
        u32 *ea, *ip;

        retval = 0;

        instword = *((u32 *)regs->nip);
        inst = instword >> 26;

        flreg = (instword >> 21) & 0x1f;
        idxreg = (instword >> 16) & 0x1f;
        disp = instword & 0xffff;

        ea = (u32 *)(regs->gpr[idxreg] + disp);
        ip = (u32 *)&current->thread.TS_FPR(flreg);

        switch ( inst )
        {
        case LFD:
                /* this is a 16 bit quantity that is sign extended
                 * so use a signed short here -- Cort
                 */
                sdisp = (instword & 0xffff);
                ea = (u32 *)(regs->gpr[idxreg] + sdisp);
                if (copy_from_user(ip, ea, sizeof(double)))
                        retval = -EFAULT;
                break;

        case LFDU:
                if (copy_from_user(ip, ea, sizeof(double)))
                        retval = -EFAULT;
                else
                        regs->gpr[idxreg] = (u32)ea;
                break;
        case LFS:
                sdisp = (instword & 0xffff);
                ea = (u32 *)(regs->gpr[idxreg] + sdisp);
                if (copy_from_user(ip, ea, sizeof(float)))
                        retval = -EFAULT;
                break;
        case STFD:
                /* this is a 16 bit quantity that is sign extended
                 * so use a signed short here -- Cort
                 */
                sdisp = (instword & 0xffff);
                ea = (u32 *)(regs->gpr[idxreg] + sdisp);
                if (copy_to_user(ea, ip, sizeof(double)))
                        retval = -EFAULT;
                break;

        case STFDU:
                if (copy_to_user(ea, ip, sizeof(double)))
                        retval = -EFAULT;
                else
                        regs->gpr[idxreg] = (u32)ea;
                break;
        case FMR:
                /* assume this is a fp move -- Cort */
                memcpy(ip, &current->thread.TS_FPR((instword>>11)&0x1f),
                       sizeof(double));
                break;
        default:
                retval = 1;
                printk("Bad emulation %s/%d\n"
                       " NIP: %08lx instruction: %08x opcode: %x "
                       "A: %x B: %x C: %x code: %x rc: %x\n",
                       current->comm,current->pid,
                       regs->nip,
                       instword,inst,
                       (instword>>16)&0x1f,
                       (instword>>11)&0x1f,
                       (instword>>6)&0x1f,
                       (instword>>1)&0x3ff,
                       instword&1);
                {
                        int pa;
                        print_8xx_pte(current->mm,regs->nip);
                        pa = get_8xx_pte(current->mm,regs->nip) & PAGE_MASK;
                        pa |= (regs->nip & ~PAGE_MASK);
                        pa = (unsigned long)__va(pa);
                        printk("Kernel VA for NIP %x ", pa);
                        print_8xx_pte(current->mm,pa);
                }
        }

        if (retval == 0)
                regs->nip += 4;

        return retval;
}