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