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