/* MN10300  Process handling code
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */
#include <linux/module.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/interrupt.h>
#include <linux/delay.h>
#include <linux/reboot.h>
#include <linux/percpu.h>
#include <linux/err.h>
#include <linux/fs.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/mmu_context.h>
#include <asm/fpu.h>
#include <asm/reset-regs.h>
#include <asm/gdb-stub.h>
#include "internal.h"

/*
 * power management idle function, if any..
 */
void (*pm_idle)(void);
EXPORT_SYMBOL(pm_idle);

/*
 * return saved PC of a blocked thread.
 */
unsigned long thread_saved_pc(struct task_struct *tsk)
{
        return ((unsigned long *) tsk->thread.sp)[3];
}

/*
 * power off function, if any
 */
void (*pm_power_off)(void);
EXPORT_SYMBOL(pm_power_off);

/*
 * we use this if we don't have any better idle routine
 */
static void default_idle(void)
{
        local_irq_disable();
        if (!need_resched())
                safe_halt();
        else
                local_irq_enable();
}

/*
 * 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)
{
        int cpu = smp_processor_id();

        /* endless idle loop with no priority at all */
        for (;;) {
                while (!need_resched()) {
                        void (*idle)(void);

                        smp_rmb();
                        idle = pm_idle;
                        if (!idle)
                                idle = default_idle;

                        irq_stat[cpu].idle_timestamp = jiffies;
                        idle();
                }

                preempt_enable_no_resched();
                schedule();
                preempt_disable();
        }
}

void release_segments(struct mm_struct *mm)
{
}

void machine_restart(char *cmd)
{
#ifdef CONFIG_GDBSTUB
        gdbstub_exit(0);
#endif

#ifdef mn10300_unit_hard_reset
        mn10300_unit_hard_reset();
#else
        mn10300_proc_hard_reset();
#endif
}

void machine_halt(void)
{
#ifdef CONFIG_GDBSTUB
        gdbstub_exit(0);
#endif
}

void machine_power_off(void)
{
#ifdef CONFIG_GDBSTUB
        gdbstub_exit(0);
#endif
}

void show_regs(struct pt_regs *regs)
{
}

/*
 * create a kernel thread
 */
int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
{
        struct pt_regs regs;

        memset(&regs, 0, sizeof(regs));

        regs.a2 = (unsigned long) fn;
        regs.d2 = (unsigned long) arg;
        regs.pc = (unsigned long) kernel_thread_helper;
        local_save_flags(regs.epsw);
        regs.epsw |= EPSW_IE | EPSW_IM_7;

        /* Ok, create the new process.. */
        return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0,
                       NULL, NULL);
}
EXPORT_SYMBOL(kernel_thread);

/*
 * free current thread data structures etc..
 */
void exit_thread(void)
{
        exit_fpu();
}

void flush_thread(void)
{
        flush_fpu();
}

void release_thread(struct task_struct *dead_task)
{
}

/*
 * we do not have to muck with descriptors here, that is
 * done in switch_mm() as needed.
 */
void copy_segments(struct task_struct *p, struct mm_struct *new_mm)
{
}

/*
 * this gets called before we allocate a new thread and copy the current task
 * into it so that we can store lazy state into memory
 */
void prepare_to_copy(struct task_struct *tsk)
{
        unlazy_fpu(tsk);
}

/*
 * set up the kernel stack for a new thread and copy arch-specific thread
 * control information
 */
int copy_thread(unsigned long clone_flags,
                unsigned long c_usp, unsigned long ustk_size,
                struct task_struct *p, struct pt_regs *kregs)
{
        struct pt_regs *c_uregs, *c_kregs, *uregs;
        unsigned long c_ksp;

        uregs = current->thread.uregs;

        c_ksp = (unsigned long) task_stack_page(p) + THREAD_SIZE;

        /* allocate the userspace exception frame and set it up */
        c_ksp -= sizeof(struct pt_regs);
        c_uregs = (struct pt_regs *) c_ksp;

        p->thread.uregs = c_uregs;
        *c_uregs = *uregs;
        c_uregs->sp = c_usp;
        c_uregs->epsw &= ~EPSW_FE; /* my FPU */

        c_ksp -= 12; /* allocate function call ABI slack */

        /* the new TLS pointer is passed in as arg #5 to sys_clone() */
        if (clone_flags & CLONE_SETTLS)
                c_uregs->e2 = __frame->d3;

        /* set up the return kernel frame if called from kernel_thread() */
        c_kregs = c_uregs;
        if (kregs != uregs) {
                c_ksp -= sizeof(struct pt_regs);
                c_kregs = (struct pt_regs *) c_ksp;
                *c_kregs = *kregs;
                c_kregs->sp = c_usp;
                c_kregs->next = c_uregs;
#ifdef CONFIG_MN10300_CURRENT_IN_E2
                c_kregs->e2 = (unsigned long) p; /* current */
#endif

                c_ksp -= 12; /* allocate function call ABI slack */
        }

        /* set up things up so the scheduler can start the new task */
        p->thread.__frame = c_kregs;
        p->thread.a3    = (unsigned long) c_kregs;
        p->thread.sp    = c_ksp;
        p->thread.pc    = (unsigned long) ret_from_fork;
        p->thread.wchan = (unsigned long) ret_from_fork;
        p->thread.usp   = c_usp;

        return 0;
}

/*
 * clone a process
 * - tlsptr is retrieved by copy_thread() from __frame->d3
 */
asmlinkage long sys_clone(unsigned long clone_flags, unsigned long newsp,
                          int __user *parent_tidptr, int __user *child_tidptr,
                          int __user *tlsptr)
{
        return do_fork(clone_flags, newsp ?: __frame->sp, __frame, 0,
                       parent_tidptr, child_tidptr);
}

asmlinkage long sys_fork(void)
{
        return do_fork(SIGCHLD, __frame->sp, __frame, 0, NULL, NULL);
}

asmlinkage long sys_vfork(void)
{
        return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, __frame->sp, __frame,
                       0, NULL, NULL);
}

asmlinkage long sys_execve(char __user *name,
                           char __user * __user *argv,
                           char __user * __user *envp)
{
        char *filename;
        int error;

        lock_kernel();

        filename = getname(name);
        error = PTR_ERR(filename);
        if (!IS_ERR(filename)) {
                error = do_execve(filename, argv, envp, __frame);
                putname(filename);
        }

        unlock_kernel();
        return error;
}

unsigned long get_wchan(struct task_struct *p)
{
        return p->thread.wchan;
}