/* 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/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/elf.h>
#include <linux/reboot.h>
#include <linux/interrupt.h>

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

#include "local.h"

asmlinkage void ret_from_fork(void);

#include <asm/pgalloc.h>

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)
{
	int cpu = smp_processor_id();

	/* endless idle loop with no priority at all */
	while (1) {
		while (!need_resched()) {
			irq_stat[cpu].idle_timestamp = jiffies;

			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(int nr, 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 - USER_CONTEXT_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 *name, char **argv, char **envp)
{
	int error;
	char * filename;

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