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