LXR linux/include/linux/mtd/xip.h

   1/*
   2 * MTD primitives for XIP support
   3 *
   4 * Author:      Nicolas Pitre
   5 * Created:     Nov 2, 2004
   6 * Copyright:   (C) 2004 MontaVista Software, Inc.
   7 *
   8 * This XIP support for MTD has been loosely inspired
   9 * by an earlier patch authored by David Woodhouse.
  10 *
  11 * This program is free software; you can redistribute it and/or modify
  12 * it under the terms of the GNU General Public License version 2 as
  13 * published by the Free Software Foundation.
  14 */
  15
  16#ifndef __LINUX_MTD_XIP_H__
  17#define __LINUX_MTD_XIP_H__
  18
  19
  20#ifdef CONFIG_MTD_XIP
  21
  22/*
  23 * We really don't want gcc to guess anything.
  24 * We absolutely _need_ proper inlining.
  25 */
  26#include <linux/compiler.h>
  27
  28/*
  29 * Function that are modifying the flash state away from array mode must
  30 * obviously not be running from flash.  The __xipram is therefore marking
  31 * those functions so they get relocated to ram.
  32 */
  33#ifdef CONFIG_XIP_KERNEL
  34#define __xipram noinline __attribute__ ((__section__ (".xiptext")))
  35#endif
  36
  37/*
  38 * Each architecture has to provide the following macros.  They must access
  39 * the hardware directly and not rely on any other (XIP) functions since they
  40 * won't be available when used (flash not in array mode).
  41 *
  42 * xip_irqpending()
  43 *
  44 *      return non zero when any hardware interrupt is pending.
  45 *
  46 * xip_currtime()
  47 *
  48 *      return a platform specific time reference to be used with
  49 *      xip_elapsed_since().
  50 *
  51 * xip_elapsed_since(x)
  52 *
  53 *      return in usecs the elapsed timebetween now and the reference x as
  54 *      returned by xip_currtime().
  55 *
  56 *      note 1: conversion to usec can be approximated, as long as the
  57 *              returned value is <= the real elapsed time.
  58 *      note 2: this should be able to cope with a few seconds without
  59 *              overflowing.
  60 *
  61 * xip_iprefetch()
  62 *
  63 *      Macro to fill instruction prefetch
  64 *      e.g. a series of nops:  asm volatile (".rep 8; nop; .endr");
  65 */
  66
  67#include <asm/mtd-xip.h>
  68
  69#ifndef xip_irqpending
  70
  71#warning "missing IRQ and timer primitives for XIP MTD support"
  72#warning "some of the XIP MTD support code will be disabled"
  73#warning "your system will therefore be unresponsive when writing or erasing flash"
  74
  75#define xip_irqpending()        (0)
  76#define xip_currtime()          (0)
  77#define xip_elapsed_since(x)    (0)
  78
  79#endif
  80
  81#ifndef xip_iprefetch
  82#define xip_iprefetch()         do { } while (0)
  83#endif
  84
  85/*
  86 * xip_cpu_idle() is used when waiting for a delay equal or larger than
  87 * the system timer tick period.  This should put the CPU into idle mode
  88 * to save power and to be woken up only when some interrupts are pending.
  89 * This should not rely upon standard kernel code.
  90 */
  91#ifndef xip_cpu_idle
  92#define xip_cpu_idle()  do { } while (0)
  93#endif
  94
  95#endif /* CONFIG_MTD_XIP */
  96
  97#ifndef __xipram
  98#define __xipram
  99#endif
 100
 101#endif /* __LINUX_MTD_XIP_H__ */
 102