/*
 *  linux/arch/h8300/kernel/process.c
 *
 * Yoshinori Sato <ysato@users.sourceforge.jp>
 *
 *  Based on:
 *
 *  linux/arch/m68knommu/kernel/process.c
 *
 *  Copyright (C) 1998  D. Jeff Dionne <jeff@ryeham.ee.ryerson.ca>,
 *                      Kenneth Albanowski <kjahds@kjahds.com>,
 *                      The Silver Hammer Group, Ltd.
 *
 *  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/errno.h>
#include <linux/module.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/interrupt.h>
#include <linux/reboot.h>
#include <linux/fs.h>

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

void (*pm_power_off)(void) = NULL;
EXPORT_SYMBOL(pm_power_off);

asmlinkage void ret_from_fork(void);

/*
 * The idle loop on an H8/300..
 */
#if !defined(CONFIG_H8300H_SIM) && !defined(CONFIG_H8S_SIM)
static void default_idle(void)
{
        local_irq_disable();
        if (!need_resched()) {
                local_irq_enable();
                /* XXX: race here! What if need_resched() gets set now? */
                __asm__("sleep");
        } else
                local_irq_enable();
}
#else
static void default_idle(void)
{
        cpu_relax();
}
#endif
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)
{
        while (1) {
                while (!need_resched())
                        idle();
                preempt_enable_no_resched();
                schedule();
                preempt_disable();
        }
}

void machine_restart(char * __unused)
{
        local_irq_disable();
        __asm__("jmp @@0"); 
}

void machine_halt(void)
{
        local_irq_disable();
        __asm__("sleep");
        for (;;);
}

void machine_power_off(void)
{
        local_irq_disable();
        __asm__("sleep");
        for (;;);
}

void show_regs(struct pt_regs * regs)
{
        printk("\nPC: %08lx  Status: %02x",
               regs->pc, regs->ccr);
        printk("\nORIG_ER0: %08lx ER0: %08lx ER1: %08lx",
               regs->orig_er0, regs->er0, regs->er1);
        printk("\nER2: %08lx ER3: %08lx ER4: %08lx ER5: %08lx",
               regs->er2, regs->er3, regs->er4, regs->er5);
        printk("\nER6' %08lx ",regs->er6);
        if (user_mode(regs))
                printk("USP: %08lx\n", rdusp());
        else
                printk("\n");
}

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

        fs = get_fs();
        set_fs (KERNEL_DS);
        clone_arg = flags | CLONE_VM;
        __asm__("mov.l sp,er3\n\t"
                "sub.l er2,er2\n\t"
                "mov.l %2,er1\n\t"
                "mov.l %1,er0\n\t"
                "trapa #0\n\t"
                "cmp.l sp,er3\n\t"
                "beq 1f\n\t"
                "mov.l %4,er0\n\t"
                "mov.l %3,er1\n\t"
                "jsr @er1\n\t"
                "mov.l %5,er0\n\t"
                "trapa #0\n"
                "1:\n\t"
                "mov.l er0,%0"
                :"=r"(retval)
                :"i"(__NR_clone),"g"(clone_arg),"g"(fn),"g"(arg),"i"(__NR_exit)
                :"er0","er1","er2","er3");
        set_fs (fs);
        return retval;
}

void flush_thread(void)
{
}

/*
 * "h8300_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 h8300_fork(struct pt_regs *regs)
{
        return -EINVAL;
}

asmlinkage int h8300_vfork(struct pt_regs *regs)
{
        return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(), regs, 0, NULL, NULL);
}

asmlinkage int h8300_clone(struct pt_regs *regs)
{
        unsigned long clone_flags;
        unsigned long newsp;

        /* syscall2 puts clone_flags in er1 and usp in er2 */
        clone_flags = regs->er1;
        newsp = regs->er2;
        if (!newsp)
                newsp  = rdusp();
        return do_fork(clone_flags, newsp, regs, 0, NULL, NULL);

}

int copy_thread(unsigned long clone_flags,
                unsigned long usp, unsigned long topstk,
                 struct task_struct * p, struct pt_regs * regs)
{
        struct pt_regs * childregs;

        childregs = (struct pt_regs *) (THREAD_SIZE + task_stack_page(p)) - 1;

        *childregs = *regs;
        childregs->retpc = (unsigned long) ret_from_fork;
        childregs->er0 = 0;

        p->thread.usp = usp;
        p->thread.ksp = (unsigned long)childregs;

        return 0;
}

/*
 * sys_execve() executes a new program.
 */
asmlinkage int sys_execve(char *name, char **argv, char **envp,int dummy,...)
{
        int error;
        char * filename;
        struct pt_regs *regs = (struct pt_regs *) ((unsigned char *)&dummy-4);

        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;
}

unsigned long thread_saved_pc(struct task_struct *tsk)
{
        return ((struct pt_regs *)tsk->thread.esp0)->pc;
}

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 pt_regs *)p->thread.ksp)->er6;
        do {
                if (fp < stack_page+sizeof(struct thread_info) ||
                    fp >= 8184+stack_page)
                        return 0;
                pc = ((unsigned long *)fp)[1];
                if (!in_sched_functions(pc))
                        return pc;
                fp = *(unsigned long *) fp;
        } while (count++ < 16);
        return 0;
}