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 | |