xip.h
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/*
* MTD primitives for XIP support
*
* Author: Nicolas Pitre
* Created: Nov 2, 2004
* Copyright: (C) 2004 MontaVista Software, Inc.
*
* This XIP support for MTD has been loosely inspired
* by an earlier patch authored by David Woodhouse.
*
* 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 __LINUX_MTD_XIP_H__
#define __LINUX_MTD_XIP_H__
#ifdef CONFIG_MTD_XIP
/*
* We really don't want gcc to guess anything.
* We absolutely _need_ proper inlining.
*/
#include <linux/compiler.h>
/*
* Function that are modifying the flash state away from array mode must
* obviously not be running from flash. The __xipram is therefore marking
* those functions so they get relocated to ram.
*/
#define __xipram noinline __attribute__ ((__section__ (".data")))
/*
* Each architecture has to provide the following macros. They must access
* the hardware directly and not rely on any other (XIP) functions since they
* won't be available when used (flash not in array mode).
*
* xip_irqpending()
*
* return non zero when any hardware interrupt is pending.
*
* xip_currtime()
*
* return a platform specific time reference to be used with
* xip_elapsed_since().
*
* xip_elapsed_since(x)
*
* return in usecs the elapsed timebetween now and the reference x as
* returned by xip_currtime().
*
* note 1: conversion to usec can be approximated, as long as the
* returned value is <= the real elapsed time.
* note 2: this should be able to cope with a few seconds without
* overflowing.
*
* xip_iprefetch()
*
* Macro to fill instruction prefetch
* e.g. a series of nops: asm volatile (".rep 8; nop; .endr");
*/
#include <asm/mtd-xip.h>
#ifndef xip_irqpending
#warning "missing IRQ and timer primitives for XIP MTD support"
#warning "some of the XIP MTD support code will be disabled"
#warning "your system will therefore be unresponsive when writing or erasing flash"
#define xip_irqpending() (0)
#define xip_currtime() (0)
#define xip_elapsed_since(x) (0)
#endif
#ifndef xip_iprefetch
#define xip_iprefetch() do { } while (0)
#endif
/*
* xip_cpu_idle() is used when waiting for a delay equal or larger than
* the system timer tick period. This should put the CPU into idle mode
* to save power and to be woken up only when some interrupts are pending.
* This should not rely upon standard kernel code.
*/
#ifndef xip_cpu_idle
#define xip_cpu_idle() do { } while (0)
#endif
#else
#define __xipram
#endif /* CONFIG_MTD_XIP */
#endif /* __LINUX_MTD_XIP_H__ */