/*
 * Copyright (C) 2004-2006 Atmel Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#ifndef __ASM_AVR32_UACCESS_H
#define __ASM_AVR32_UACCESS_H

#include <linux/errno.h>
#include <linux/sched.h>

#define VERIFY_READ	0
#define VERIFY_WRITE	1

typedef struct {
	unsigned int is_user_space;
} mm_segment_t;

/*
 * The fs value determines whether argument validity checking should be
 * performed or not.  If get_fs() == USER_DS, checking is performed, with
 * get_fs() == KERNEL_DS, checking is bypassed.
 *
 * For historical reasons (Data Segment Register?), these macros are misnamed.
 */
#define MAKE_MM_SEG(s)	((mm_segment_t) { (s) })
#define segment_eq(a,b)	((a).is_user_space == (b).is_user_space)

#define USER_ADDR_LIMIT 0x80000000

#define KERNEL_DS	MAKE_MM_SEG(0)
#define USER_DS		MAKE_MM_SEG(1)

#define get_ds()	(KERNEL_DS)

static inline mm_segment_t get_fs(void)
{
	return MAKE_MM_SEG(test_thread_flag(TIF_USERSPACE));
}

static inline void set_fs(mm_segment_t s)
{
	if (s.is_user_space)
		set_thread_flag(TIF_USERSPACE);
	else
		clear_thread_flag(TIF_USERSPACE);
}

/*
 * Test whether a block of memory is a valid user space address.
 * Returns 0 if the range is valid, nonzero otherwise.
 *
 * We do the following checks:
 *   1. Is the access from kernel space?
 *   2. Does (addr + size) set the carry bit?
 *   3. Is (addr + size) a negative number (i.e. >= 0x80000000)?
 *
 * If yes on the first check, access is granted.
 * If no on any of the others, access is denied.
 */
#define __range_ok(addr, size)						\
	(test_thread_flag(TIF_USERSPACE)				\
	 && (((unsigned long)(addr) >= 0x80000000)			\
	     || ((unsigned long)(size) > 0x80000000)			\
	     || (((unsigned long)(addr) + (unsigned long)(size)) > 0x80000000)))

#define access_ok(type, addr, size) (likely(__range_ok(addr, size) == 0))

/* Generic arbitrary sized copy. Return the number of bytes NOT copied */
extern __kernel_size_t __copy_user(void *to, const void *from,
				   __kernel_size_t n);

extern __kernel_size_t copy_to_user(void __user *to, const void *from,
				    __kernel_size_t n);
extern __kernel_size_t copy_from_user(void *to, const void __user *from,
				      __kernel_size_t n);

static inline __kernel_size_t __copy_to_user(void __user *to, const void *from,
					     __kernel_size_t n)
{
	return __copy_user((void __force *)to, from, n);
}
static inline __kernel_size_t __copy_from_user(void *to,
					       const void __user *from,
					       __kernel_size_t n)
{
	return __copy_user(to, (const void __force *)from, n);
}

#define __copy_to_user_inatomic __copy_to_user
#define __copy_from_user_inatomic __copy_from_user

/*
 * put_user: - Write a simple value into user space.
 * @x:   Value to copy to user space.
 * @ptr: Destination address, in user space.
 *
 * Context: User context only.  This function may sleep.
 *
 * This macro copies a single simple value from kernel space to user
 * space.  It supports simple types like char and int, but not larger
 * data types like structures or arrays.
 *
 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 * to the result of dereferencing @ptr.
 *
 * Returns zero on success, or -EFAULT on error.
 */
#define put_user(x,ptr)	\
	__put_user_check((x),(ptr),sizeof(*(ptr)))