/* process.c: FRV specific parts of process handling
 *
 * Copyright (C) 2003-5 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 * - Derived from arch/m68k/kernel/process.c
 *
 * 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 <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/elf.h>
#include <linux/reboot.h>
#include <linux/interrupt.h>
#include <linux/pagemap.h>

#include <asm/asm-offsets.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/setup.h>
#include <asm/pgtable.h>
#include <asm/tlb.h>
#include <asm/gdb-stub.h>
#include <asm/mb-regs.h>

#include "local.h"

asmlinkage void ret_from_fork(void);

#include <asm/pgalloc.h>

void (*pm_power_off)(void);
EXPORT_SYMBOL(pm_power_off);

struct task_struct *alloc_task_struct(void)
{
        struct task_struct *p = kmalloc(THREAD_SIZE, GFP_KERNEL);
        if (p)
                atomic_set((atomic_t *)(p+1), 1);
        return p;
}

void free_task_struct(struct task_struct *p)
{
        if (atomic_dec_and_test((atomic_t *)(p+1)))
                kfree(p);
}

static void core_sleep_idle(void)
{
#ifdef LED_DEBUG_SLEEP
        /* Show that we're sleeping... */
        __set_LEDS(0x55aa);
#endif
        frv_cpu_core_sleep();
#ifdef LED_DEBUG_SLEEP
        /* ... and that we woke up */
        __set_LEDS(0);
#endif
        mb();
}

void (*idle)(void) = core_sleep_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 */
        while (1) {
                while (!need_resched()) {
                        check_pgt_cache();

                        if (!frv_dma_inprogress && idle)
                                idle();
                }

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

void machine_restart(char * __unused)
{
        unsigned long reset_addr;
#ifdef CONFIG_GDBSTUB
        gdbstub_exit(0);
#endif

        if (PSR_IMPLE(__get_PSR()) == PSR_IMPLE_FR551)
                reset_addr = 0xfefff500;
        else
                reset_addr = 0xfeff0500;

        /* Software reset. */
        asm volatile("      dcef @(gr0,gr0),1 ! membar !"
                     "      sti     %1,@(%0,0) !"
                     "      nop ! nop ! nop ! nop ! nop ! "
                     "      nop ! nop ! nop ! nop ! nop ! "
                     "      nop ! nop ! nop ! nop ! nop ! "
                     "      nop ! nop ! nop ! nop ! nop ! "
                     : : "r" (reset_addr), "r" (1) );

        for (;;)
                ;
}

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

        for (;;);
}

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

        for (;;);
}

void flush_thread(void)
{
#if 0 //ndef NO_FPU
        unsigned long zero = 0;
#endif
        set_fs(USER_DS);
}

inline unsigned long user_stack(const struct pt_regs *regs)
{
        while (regs->next_frame)
                regs = regs->next_frame;
        return user_mode(regs) ? regs->sp : 0;
}

asmlinkage int sys_fork(void)
{
#ifndef CONFIG_MMU
        /* fork almost works, enough to trick you into looking elsewhere:-( */
        return -EINVAL;
#else
        return do_fork(SIGCHLD, user_stack(__frame), __frame, 0, NULL, NULL);
#endif
}

asmlinkage int sys_vfork(void)
{
        return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, user_stack(__frame), __frame, 0,
                       NULL, NULL);
}

/*****************************************************************************/
/*
 * clone a process
 * - tlsptr is retrieved by copy_thread()
 */
asmlinkage int sys_clone(unsigned long clone_flags, unsigned long newsp,
                         int __user *parent_tidptr, int __user *child_tidptr,
                         int __user *tlsptr)
{
        if (!newsp)
                newsp = user_stack(__frame);
        return do_fork(clone_flags, newsp, __frame, 0, parent_tidptr, child_tidptr);
} /* end sys_clone() */

/*****************************************************************************/
/*
 * This gets called before we allocate a new thread and copy
 * the current task into it.
 */
void prepare_to_copy(struct task_struct *tsk)
{
        //unlazy_fpu(tsk);
} /* end prepare_to_copy() */

/*****************************************************************************/
/*
 * set up the kernel stack and exception frames for a new process
 */
int copy_thread(unsigned long clone_flags,
                unsigned long usp, unsigned long topstk,
                struct task_struct *p, struct pt_regs *regs)
{
        struct pt_regs *childregs0, *childregs, *regs0;

        regs0 = __kernel_frame0_ptr;
        childregs0 = (struct pt_regs *)
                (task_stack_page(p) + THREAD_SIZE - FRV_FRAME0_SIZE);
        childregs = childregs0;

        /* set up the userspace frame (the only place that the USP is stored) */
        *childregs0 = *regs0;

        childregs0->gr8         = 0;
        childregs0->sp          = usp;
        childregs0->next_frame  = NULL;

        /* set up the return kernel frame if called from kernel_thread() */
        if (regs != regs0) {
                childregs--;
                *childregs = *regs;
                childregs->sp = (unsigned long) childregs0;
                childregs->next_frame = childregs0;
                childregs->gr15 = (unsigned long) task_thread_info(p);
                childregs->gr29 = (unsigned long) p;
        }

        p->set_child_tid = p->clear_child_tid = NULL;

        p->thread.frame  = childregs;
        p->thread.curr   = p;
        p->thread.sp     = (unsigned long) childregs;
        p->thread.fp     = 0;
        p->thread.lr     = 0;
        p->thread.pc     = (unsigned long) ret_from_fork;
        p->thread.frame0 = childregs0;

        /* the new TLS pointer is passed in as arg #5 to sys_clone() */
        if (clone_flags & CLONE_SETTLS)
                childregs->gr29 = childregs->gr12;

        save_user_regs(p->thread.user);

        return 0;
} /* end copy_thread() */

/*
 * sys_execve() executes a new program.
 */
asmlinkage int sys_execve(char __user *name, char __user * __user *argv, char __user * __user *envp)
{
        int error;
        char * filename;

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

unsigned long get_wchan(struct task_struct *p)
{
        struct pt_regs *regs0;
        unsigned long fp, pc;
        unsigned long stack_limit;
        int count = 0;
        if (!p || p == current || p->state == TASK_RUNNING)
                return 0;

        stack_limit = (unsigned long) (p + 1);
        fp = p->thread.fp;
        regs0 = p->thread.frame0;

        do {
                if (fp < stack_limit || fp >= (unsigned long) regs0 || fp & 3)
                        return 0;

                pc = ((unsigned long *) fp)[2];

                /* FIXME: This depends on the order of these functions. */
                if (!in_sched_functions(pc))
                        return pc;

                fp = *(unsigned long *) fp;
        } while (count++ < 16);

        return 0;
}

unsigned long thread_saved_pc(struct task_struct *tsk)
{
        /* Check whether the thread is blocked in resume() */
        if (in_sched_functions(tsk->thread.pc))
                return ((unsigned long *)tsk->thread.fp)[2];
        else
                return tsk->thread.pc;
}

int elf_check_arch(const struct elf32_hdr *hdr)
{
        unsigned long hsr0 = __get_HSR(0);
        unsigned long psr = __get_PSR();

        if (hdr->e_machine != EM_FRV)
                return 0;

        switch (hdr->e_flags & EF_FRV_GPR_MASK) {
        case EF_FRV_GPR64:
                if ((hsr0 & HSR0_GRN) == HSR0_GRN_32)
                        return 0;
        case EF_FRV_GPR32:
        case 0:
                break;
        default:
                return 0;
        }

        switch (hdr->e_flags & EF_FRV_FPR_MASK) {
        case EF_FRV_FPR64:
                if ((hsr0 & HSR0_FRN) == HSR0_FRN_32)
                        return 0;
        case EF_FRV_FPR32:
        case EF_FRV_FPR_NONE:
        case 0:
                break;
        default:
                return 0;
        }

        if ((hdr->e_flags & EF_FRV_MULADD) == EF_FRV_MULADD)
                if (PSR_IMPLE(psr) != PSR_IMPLE_FR405 &&
                    PSR_IMPLE(psr) != PSR_IMPLE_FR451)
                        return 0;

        switch (hdr->e_flags & EF_FRV_CPU_MASK) {
        case EF_FRV_CPU_GENERIC:
                break;
        case EF_FRV_CPU_FR300:
        case EF_FRV_CPU_SIMPLE:
        case EF_FRV_CPU_TOMCAT:
        default:
                return 0;
        case EF_FRV_CPU_FR400:
                if (PSR_IMPLE(psr) != PSR_IMPLE_FR401 &&
                    PSR_IMPLE(psr) != PSR_IMPLE_FR405 &&
                    PSR_IMPLE(psr) != PSR_IMPLE_FR451 &&
                    PSR_IMPLE(psr) != PSR_IMPLE_FR551)
                        return 0;
                break;
        case EF_FRV_CPU_FR450:
                if (PSR_IMPLE(psr) != PSR_IMPLE_FR451)
                        return 0;
                break;
        case EF_FRV_CPU_FR500:
                if (PSR_IMPLE(psr) != PSR_IMPLE_FR501)
                        return 0;
                break;
        case EF_FRV_CPU_FR550:
                if (PSR_IMPLE(psr) != PSR_IMPLE_FR551)
                        return 0;
                break;
        }

        return 1;
}

int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpregs)
{
        memcpy(fpregs,
               &current->thread.user->f,
               sizeof(current->thread.user->f));
        return 1;
}