/*
 *  linux/arch/m68k/kernel/process.c
 *
 *  Copyright (C) 1995  Hamish Macdonald
 *
 *  68060 fixes by Jesper Skov
 */

/*
 * This file handles the architecture-dependent parts of process handling..
 */

#include <linux/config.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/a.out.h>
#include <linux/reboot.h>

#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/traps.h>
#include <asm/machdep.h>
#include <asm/setup.h>
#include <asm/pgtable.h>

/*
 * Initial task structure. Make this a per-architecture thing,
 * because different architectures tend to have different
 * alignment requirements and potentially different initial
 * setup.
 */
static struct fs_struct init_fs = INIT_FS;
static struct files_struct init_files = INIT_FILES;
static struct signal_struct init_signals = INIT_SIGNALS;
struct mm_struct init_mm = INIT_MM(init_mm);

union task_union init_task_union
__attribute__((section("init_task"), aligned(KTHREAD_SIZE)))
        = { task: INIT_TASK(init_task_union.task) };

asmlinkage void ret_from_fork(void);


/*
 * The idle loop on an m68k..
 */
static void default_idle(void)
{
        while(1) {
                if (!current->need_resched)
#if defined(MACH_ATARI_ONLY) && !defined(CONFIG_HADES)
                        /* block out HSYNC on the atari (falcon) */
                        __asm__("stop #0x2200" : : : "cc");
#else
                        __asm__("stop #0x2000" : : : "cc");
#endif
                schedule();
                check_pgt_cache();
        }
}

void (*idle)(void) = default_idle;

/*
 * The idle thread. There's no useful work to be
 * done, so just try to conserve power and have a
 * low exit latency (ie sit in a loop waiting for
 * somebody to say that they'd like to reschedule)
 */
void cpu_idle(void)
{
        /* endless idle loop with no priority at all */
        init_idle();
        current->nice = 20;
        current->counter = -100;
        idle();
}

void machine_restart(char * __unused)
{
        if (mach_reset)
                mach_reset();
        for (;;);
}

void machine_halt(void)
{
        if (mach_halt)
                mach_halt();
        for (;;);
}

void machine_power_off(void)
{
        if (mach_power_off)
                mach_power_off();
        for (;;);
}

void show_regs(struct pt_regs * regs)
{
        printk("\n");
        printk("Format %02x  Vector: %04x  PC: %08lx  Status: %04x    %s\n",
               regs->format, regs->vector, regs->pc, regs->sr, print_tainted());
        printk("ORIG_D0: %08lx  D0: %08lx  A2: %08lx  A1: %08lx\n",
               regs->orig_d0, regs->d0, regs->a2, regs->a1);
        printk("A0: %08lx  D5: %08lx  D4: %08lx\n",
               regs->a0, regs->d5, regs->d4);
        printk("D3: %08lx  D2: %08lx  D1: %08lx\n",
               regs->d3, regs->d2, regs->d1);
        if (!(regs->sr & PS_S))
                printk("USP: %08lx\n", rdusp());
}

/*
 * Create a kernel thread
 */
int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
        int pid;
        mm_segment_t fs;

        fs = get_fs();
        set_fs (KERNEL_DS);

        {
        register long retval __asm__ ("d0");
        register long clone_arg __asm__ ("d1") = flags | CLONE_VM;

        retval = __NR_clone;
        __asm__ __volatile__
          ("clrl %%d2\n\t"
           "trap #0\n\t"                /* Linux/m68k system call */
           "tstl %0\n\t"                /* child or parent */
           "jne 1f\n\t"                 /* parent - jump */
           "lea %%sp@(%c7),%6\n\t"      /* reload current */
           "movel %3,%%sp@-\n\t"        /* push argument */
           "jsr %4@\n\t"                /* call fn */
           "movel %0,%%d1\n\t"          /* pass exit value */
           "movel %2,%%d0\n\t"          /* exit */
           "trap #0\n"
           "1:"
           : "+d" (retval)
           : "i" (__NR_clone), "i" (__NR_exit),
             "r" (arg), "a" (fn), "d" (clone_arg), "r" (current),
             "i" (-KTHREAD_SIZE)
           : "d2");

        pid = retval;
        }

        set_fs (fs);
        return pid;
}

void flush_thread(void)
{
        unsigned long zero = 0;
        set_fs(USER_DS);
        current->thread.fs = __USER_DS;
        if (!FPU_IS_EMU)
                asm volatile (".chip 68k/68881\n\t"
                              "frestore %0@\n\t"
                              ".chip 68k" : : "a" (&zero));
}

/*
 * "m68k_fork()".. By the time we get here, the
 * non-volatile registers have also been saved on the
 * stack. We do some ugly pointer stuff here.. (see
 * also copy_thread)
 */

asmlinkage int m68k_fork(struct pt_regs *regs)
{
        return do_fork(SIGCHLD, rdusp(), regs, 0);
}

asmlinkage int m68k_vfork(struct pt_regs *regs)
{
        return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(), regs, 0);
}

asmlinkage int m68k_clone(struct pt_regs *regs)
{
        unsigned long clone_flags;
        unsigned long newsp;

        /* syscall2 puts clone_flags in d1 and usp in d2 */
        clone_flags = regs->d1;
        newsp = regs->d2;
        if (!newsp)
                newsp = rdusp();
        return do_fork(clone_flags, newsp, regs, 0);
}

int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
                 unsigned long unused,
                 struct task_struct * p, struct pt_regs * regs)
{
        struct pt_regs * childregs;
        struct switch_stack * childstack, *stack;
        unsigned long stack_offset, *retp;

        stack_offset = KTHREAD_SIZE - sizeof(struct pt_regs);
        childregs = (struct pt_regs *) ((unsigned long) p + stack_offset);

        *childregs = *regs;
        childregs->d0 = 0;

        retp = ((unsigned long *) regs);
        stack = ((struct switch_stack *) retp) - 1;

        childstack = ((struct switch_stack *) childregs) - 1;
        *childstack = *stack;
        childstack->retpc = (unsigned long)ret_from_fork;

        p->thread.usp = usp;
        p->thread.ksp = (unsigned long)childstack;
        /*
         * Must save the current SFC/DFC value, NOT the value when
         * the parent was last descheduled - RGH  10-08-96
         */
        p->thread.fs = get_fs().seg;

        if (!FPU_IS_EMU) {
                /* Copy the current fpu state */
                asm volatile ("fsave %0" : : "m" (p->thread.fpstate[0]) : "memory");

                if (!CPU_IS_060 ? p->thread.fpstate[0] : p->thread.fpstate[2])
                  asm volatile ("fmovemx %/fp0-%/fp7,%0\n\t"
                                "fmoveml %/fpiar/%/fpcr/%/fpsr,%1"
                                : : "m" (p->thread.fp[0]), "m" (p->thread.fpcntl[0])
                                : "memory");
                /* Restore the state in case the fpu was busy */
                asm volatile ("frestore %0" : : "m" (p->thread.fpstate[0]));
        }

        return 0;
}

/* Fill in the fpu structure for a core dump.  */

int dump_fpu (struct pt_regs *regs, struct user_m68kfp_struct *fpu)
{
        char fpustate[216];

        if (FPU_IS_EMU) {
                int i;

                memcpy(fpu->fpcntl, current->thread.fpcntl, 12);
                memcpy(fpu->fpregs, current->thread.fp, 96);
                /* Convert internal fpu reg representation
                 * into long double format
                 */
                for (i = 0; i < 24; i += 3)
                        fpu->fpregs[i] = ((fpu->fpregs[i] & 0xffff0000) << 15) |
                                         ((fpu->fpregs[i] & 0x0000ffff) << 16);
                return 1;
        }

        /* First dump the fpu context to avoid protocol violation.  */
        asm volatile ("fsave %0" :: "m" (fpustate[0]) : "memory");
        if (!CPU_IS_060 ? !fpustate[0] : !fpustate[2])
                return 0;

        asm volatile ("fmovem %/fpiar/%/fpcr/%/fpsr,%0"
                :: "m" (fpu->fpcntl[0])
                : "memory");
        asm volatile ("fmovemx %/fp0-%/fp7,%0"
                :: "m" (fpu->fpregs[0])
                : "memory");
        return 1;
}

/*
 * fill in the user structure for a core dump..
 */
void dump_thread(struct pt_regs * regs, struct user * dump)
{
        struct switch_stack *sw;

/* changed the size calculations - should hopefully work better. lbt */
        dump->magic = CMAGIC;
        dump->start_code = 0;
        dump->start_stack = rdusp() & ~(PAGE_SIZE - 1);
        dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT;
        dump->u_dsize = ((unsigned long) (current->mm->brk +
                                          (PAGE_SIZE-1))) >> PAGE_SHIFT;
        dump->u_dsize -= dump->u_tsize;
        dump->u_ssize = 0;

        if (dump->start_stack < TASK_SIZE)
                dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT;

        dump->u_ar0 = (struct user_regs_struct *)((int)&dump->regs - (int)dump);
        sw = ((struct switch_stack *)regs) - 1;
        dump->regs.d1 = regs->d1;
        dump->regs.d2 = regs->d2;
        dump->regs.d3 = regs->d3;
        dump->regs.d4 = regs->d4;
        dump->regs.d5 = regs->d5;
        dump->regs.d6 = sw->d6;
        dump->regs.d7 = sw->d7;
        dump->regs.a0 = regs->a0;
        dump->regs.a1 = regs->a1;
        dump->regs.a2 = regs->a2;
        dump->regs.a3 = sw->a3;
        dump->regs.a4 = sw->a4;
        dump->regs.a5 = sw->a5;
        dump->regs.a6 = sw->a6;
        dump->regs.d0 = regs->d0;
        dump->regs.orig_d0 = regs->orig_d0;
        dump->regs.stkadj = regs->stkadj;
        dump->regs.sr = regs->sr;
        dump->regs.pc = regs->pc;
        dump->regs.fmtvec = (regs->format << 12) | regs->vector;
        /* dump floating point stuff */
        dump->u_fpvalid = dump_fpu (regs, &dump->m68kfp);
}

/*
 * sys_execve() executes a new program.
 */
asmlinkage int sys_execve(char *name, char **argv, char **envp)
{
        int error;
        char * filename;
        struct pt_regs *regs = (struct pt_regs *) &name;

        lock_kernel();
        filename = getname(name);
        error = PTR_ERR(filename);
        if (IS_ERR(filename))
                goto out;
        error = do_execve(filename, argv, envp, regs);
        putname(filename);
out:
        unlock_kernel();
        return error;
}

/*
 * These bracket the sleeping functions..
 */
extern void scheduling_functions_start_here(void);
extern void scheduling_functions_end_here(void);
#define first_sched     ((unsigned long) scheduling_functions_start_here)
#define last_sched      ((unsigned long) scheduling_functions_end_here)

unsigned long get_wchan(struct task_struct *p)
{
        unsigned long fp, pc;
        unsigned long stack_page;
        int count = 0;
        if (!p || p == current || p->state == TASK_RUNNING)
                return 0;

        stack_page = (unsigned long)p;
        fp = ((struct switch_stack *)p->thread.ksp)->a6;
        do {
                if (fp < stack_page+sizeof(struct task_struct) ||
                    fp >= 8184+stack_page)
                        return 0;
                pc = ((unsigned long *)fp)[1];
                /* FIXME: This depends on the order of these functions. */
                if (pc < first_sched || pc >= last_sched)
                        return pc;
                fp = *(unsigned long *) fp;
        } while (count++ < 16);
        return 0;
}