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#define __xipram noinline __attribute__ ((__section__ (".data")))
  34
  35/*
  36 * Each architecture has to provide the following macros.  They must access
  37 * the hardware directly and not rely on any other (XIP) functions since they
  38 * won't be available when used (flash not in array mode).
  39 *
  40 * xip_irqpending()
  41 *
  42 *      return non zero when any hardware interrupt is pending.
  43 *
  44 * xip_currtime()
  45 *
  46 *      return a platform specific time reference to be used with
  47 *      xip_elapsed_since().
  48 *
  49 * xip_elapsed_since(x)
  50 *
  51 *      return in usecs the elapsed timebetween now and the reference x as
  52 *      returned by xip_currtime().
  53 *
  54 *      note 1: conversion to usec can be approximated, as long as the
  55 *              returned value is <= the real elapsed time.
  56 *      note 2: this should be able to cope with a few seconds without
  57 *              overflowing.
  58 *
  59 * xip_iprefetch()
  60 *
  61 *      Macro to fill instruction prefetch
  62 *      e.g. a series of nops:  asm volatile (".rep 8; nop; .endr");
  63 */
  64
  65#include <asm/mtd-xip.h>
  66
  67#ifndef xip_irqpending
  68
  69#warning "missing IRQ and timer primitives for XIP MTD support"
  70#warning "some of the XIP MTD support code will be disabled"
  71#warning "your system will therefore be unresponsive when writing or erasing flash"
  72
  73#define xip_irqpending()        (0)
  74#define xip_currtime()          (0)
  75#define xip_elapsed_since(x)    (0)
  76
  77#endif
  78
  79#ifndef xip_iprefetch
  80#define xip_iprefetch()         do { } while (0)
  81#endif
  82
  83/*
  84 * xip_cpu_idle() is used when waiting for a delay equal or larger than
  85 * the system timer tick period.  This should put the CPU into idle mode
  86 * to save power and to be woken up only when some interrupts are pending.
  87 * This should not rely upon standard kernel code.
  88 */
  89#ifndef xip_cpu_idle
  90#define xip_cpu_idle()  do { } while (0)
  91#endif
  92
  93#else
  94
  95#define __xipram
  96
  97#endif /* CONFIG_MTD_XIP */
  98
  99#endif /* __LINUX_MTD_XIP_H__ */
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