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__ */ 100