xip.h 2.7 KB

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  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. * $Id: xip.h,v 1.1.1.1 2007/06/12 07:27:16 eyryu Exp $
  16. */
  17. #ifndef __LINUX_MTD_XIP_H__
  18. #define __LINUX_MTD_XIP_H__
  19. #ifdef CONFIG_MTD_XIP
  20. /*
  21. * We really don't want gcc to guess anything.
  22. * We absolutely _need_ proper inlining.
  23. */
  24. #include <linux/compiler.h>
  25. /*
  26. * Function that are modifying the flash state away from array mode must
  27. * obviously not be running from flash. The __xipram is therefore marking
  28. * those functions so they get relocated to ram.
  29. */
  30. #define __xipram noinline __attribute__ ((__section__ (".data")))
  31. /*
  32. * Each architecture has to provide the following macros. They must access
  33. * the hardware directly and not rely on any other (XIP) functions since they
  34. * won't be available when used (flash not in array mode).
  35. *
  36. * xip_irqpending()
  37. *
  38. * return non zero when any hardware interrupt is pending.
  39. *
  40. * xip_currtime()
  41. *
  42. * return a platform specific time reference to be used with
  43. * xip_elapsed_since().
  44. *
  45. * xip_elapsed_since(x)
  46. *
  47. * return in usecs the elapsed timebetween now and the reference x as
  48. * returned by xip_currtime().
  49. *
  50. * note 1: convertion to usec can be approximated, as long as the
  51. * returned value is <= the real elapsed time.
  52. * note 2: this should be able to cope with a few seconds without
  53. * overflowing.
  54. *
  55. * xip_iprefetch()
  56. *
  57. * Macro to fill instruction prefetch
  58. * e.g. a series of nops: asm volatile (".rep 8; nop; .endr");
  59. */
  60. #include <asm/mtd-xip.h>
  61. #ifndef xip_irqpending
  62. #warning "missing IRQ and timer primitives for XIP MTD support"
  63. #warning "some of the XIP MTD support code will be disabled"
  64. #warning "your system will therefore be unresponsive when writing or erasing flash"
  65. #define xip_irqpending() (0)
  66. #define xip_currtime() (0)
  67. #define xip_elapsed_since(x) (0)
  68. #endif
  69. #ifndef xip_iprefetch
  70. #define xip_iprefetch() do { } while (0)
  71. #endif
  72. /*
  73. * xip_cpu_idle() is used when waiting for a delay equal or larger than
  74. * the system timer tick period. This should put the CPU into idle mode
  75. * to save power and to be woken up only when some interrupts are pending.
  76. * This should not rely upon standard kernel code.
  77. */
  78. #ifndef xip_cpu_idle
  79. #define xip_cpu_idle() do { } while (0)
  80. #endif
  81. #else
  82. #define __xipram
  83. #endif /* CONFIG_MTD_XIP */
  84. #endif /* __LINUX_MTD_XIP_H__ */