1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  * MTD primitives for XIP support
4  *
5  * Author:	Nicolas Pitre
6  * Created:	Nov 2, 2004
7  * Copyright:	(C) 2004 MontaVista Software, Inc.
8  *
9  * This XIP support for MTD has been loosely inspired
10  * by an earlier patch authored by David Woodhouse.
11  */
12 
13 #ifndef __LINUX_MTD_XIP_H__
14 #define __LINUX_MTD_XIP_H__
15 
16 
17 #ifdef CONFIG_MTD_XIP
18 
19 /*
20  * We really don't want gcc to guess anything.
21  * We absolutely _need_ proper inlining.
22  */
23 #include <linux/compiler.h>
24 
25 /*
26  * Function that are modifying the flash state away from array mode must
27  * obviously not be running from flash.  The __xipram is therefore marking
28  * those functions so they get relocated to ram.
29  */
30 #ifdef CONFIG_XIP_KERNEL
31 #define __xipram noinline __section(".xiptext")
32 #endif
33 
34 /*
35  * Each architecture has to provide the following macros.  They must access
36  * the hardware directly and not rely on any other (XIP) functions since they
37  * won't be available when used (flash not in array mode).
38  *
39  * xip_irqpending()
40  *
41  * 	return non zero when any hardware interrupt is pending.
42  *
43  * xip_currtime()
44  *
45  * 	return a platform specific time reference to be used with
46  * 	xip_elapsed_since().
47  *
48  * xip_elapsed_since(x)
49  *
50  * 	return in usecs the elapsed timebetween now and the reference x as
51  * 	returned by xip_currtime().
52  *
53  * 	note 1: conversion to usec can be approximated, as long as the
54  * 		returned value is <= the real elapsed time.
55  * 	note 2: this should be able to cope with a few seconds without
56  * 		overflowing.
57  *
58  * xip_iprefetch()
59  *
60  *      Macro to fill instruction prefetch
61  *	e.g. a series of nops:  asm volatile (".rep 8; nop; .endr");
62  */
63 
64 #include <asm/mtd-xip.h>
65 
66 #ifndef xip_irqpending
67 
68 #warning "missing IRQ and timer primitives for XIP MTD support"
69 #warning "some of the XIP MTD support code will be disabled"
70 #warning "your system will therefore be unresponsive when writing or erasing flash"
71 
72 #define xip_irqpending()	(0)
73 #define xip_currtime()		(0)
74 #define xip_elapsed_since(x)	(0)
75 
76 #endif
77 
78 #ifndef xip_iprefetch
79 #define xip_iprefetch()		do { } while (0)
80 #endif
81 
82 /*
83  * xip_cpu_idle() is used when waiting for a delay equal or larger than
84  * the system timer tick period.  This should put the CPU into idle mode
85  * to save power and to be woken up only when some interrupts are pending.
86  * This should not rely upon standard kernel code.
87  */
88 #ifndef xip_cpu_idle
89 #define xip_cpu_idle()  do { } while (0)
90 #endif
91 
92 #endif /* CONFIG_MTD_XIP */
93 
94 #ifndef __xipram
95 #define __xipram
96 #endif
97 
98 #endif /* __LINUX_MTD_XIP_H__ */
99