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 2007/08/03 18:53:44 Exp $
16 */
17
18#ifndef __LINUX_MTD_XIP_H__
19#define __LINUX_MTD_XIP_H__
20
21
22#ifdef CONFIG_MTD_XIP
23
24/*
25 * We really don't want gcc to guess anything.
26 * We absolutely _need_ proper inlining.
27 */
28#include <linux/compiler.h>
29
30/*
31 * Function that are modifying the flash state away from array mode must
32 * obviously not be running from flash.  The __xipram is therefore marking
33 * those functions so they get relocated to ram.
34 */
35#define __xipram noinline __attribute__ ((__section__ (".data")))
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: convertion 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#else
96
97#define __xipram
98
99#endif /* CONFIG_MTD_XIP */
100
101#endif /* __LINUX_MTD_XIP_H__ */
102