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 1.5 2005/11/07 11:14:55 gleixner Exp $ 16 */ 17 18 #ifndef __LINUX_MTD_XIP_H__ 19 #define __LINUX_MTD_XIP_H__ 20 21 #include <linux/config.h> 22 23 #ifdef CONFIG_MTD_XIP 24 25 /* 26 * We really don't want gcc to guess anything. 27 * We absolutely _need_ proper inlining. 28 */ 29 #include <linux/compiler.h> 30 31 /* 32 * Function that are modifying the flash state away from array mode must 33 * obviously not be running from flash. The __xipram is therefore marking 34 * those functions so they get relocated to ram. 35 */ 36 #define __xipram noinline __attribute__ ((__section__ (".data"))) 37 38 /* 39 * Each architecture has to provide the following macros. They must access 40 * the hardware directly and not rely on any other (XIP) functions since they 41 * won't be available when used (flash not in array mode). 42 * 43 * xip_irqpending() 44 * 45 * return non zero when any hardware interrupt is pending. 46 * 47 * xip_currtime() 48 * 49 * return a platform specific time reference to be used with 50 * xip_elapsed_since(). 51 * 52 * xip_elapsed_since(x) 53 * 54 * return in usecs the elapsed timebetween now and the reference x as 55 * returned by xip_currtime(). 56 * 57 * note 1: convertion to usec can be approximated, as long as the 58 * returned value is <= the real elapsed time. 59 * note 2: this should be able to cope with a few seconds without 60 * overflowing. 61 * 62 * xip_iprefetch() 63 * 64 * Macro to fill instruction prefetch 65 * e.g. a series of nops: asm volatile (".rep 8; nop; .endr"); 66 */ 67 68 #include <asm/mtd-xip.h> 69 70 #ifndef xip_irqpending 71 72 #warning "missing IRQ and timer primitives for XIP MTD support" 73 #warning "some of the XIP MTD support code will be disabled" 74 #warning "your system will therefore be unresponsive when writing or erasing flash" 75 76 #define xip_irqpending() (0) 77 #define xip_currtime() (0) 78 #define xip_elapsed_since(x) (0) 79 80 #endif 81 82 #ifndef xip_iprefetch 83 #define xip_iprefetch() do { } while (0) 84 #endif 85 86 /* 87 * xip_cpu_idle() is used when waiting for a delay equal or larger than 88 * the system timer tick period. This should put the CPU into idle mode 89 * to save power and to be woken up only when some interrupts are pending. 90 * This should not rely upon standard kernel code. 91 */ 92 #ifndef xip_cpu_idle 93 #define xip_cpu_idle() do { } while (0) 94 #endif 95 96 #else 97 98 #define __xipram 99 100 #endif /* CONFIG_MTD_XIP */ 101 102 #endif /* __LINUX_MTD_XIP_H__ */ 103