[mirror_ubuntu-bionic-kernel.git] / include / linux / mtd / xip.h

/*
 * MTD primitives for XIP support
 *
 * Author:	Nicolas Pitre
 * Created:	Nov 2, 2004
 * Copyright:	(C) 2004 MontaVista Software, Inc.
 *
 * This XIP support for MTD has been loosely inspired
 * by an earlier patch authored by David Woodhouse.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#ifndef __LINUX_MTD_XIP_H__
#define __LINUX_MTD_XIP_H__


#ifdef CONFIG_MTD_XIP

/*
 * We really don't want gcc to guess anything.
 * We absolutely _need_ proper inlining.
 */
#include <linux/compiler.h>

/*
 * Function that are modifying the flash state away from array mode must
 * obviously not be running from flash.  The __xipram is therefore marking
 * those functions so they get relocated to ram.
 */
#define __xipram noinline __attribute__ ((__section__ (".data")))

/*
 * Each architecture has to provide the following macros.  They must access
 * the hardware directly and not rely on any other (XIP) functions since they
 * won't be available when used (flash not in array mode).
 *
 * xip_irqpending()
 *
 * 	return non zero when any hardware interrupt is pending.
 *
 * xip_currtime()
 *
 * 	return a platform specific time reference to be used with
 * 	xip_elapsed_since().
 *
 * xip_elapsed_since(x)
 *
 * 	return in usecs the elapsed timebetween now and the reference x as
 * 	returned by xip_currtime().
 *
 * 	note 1: conversion to usec can be approximated, as long as the
 * 		returned value is <= the real elapsed time.
 * 	note 2: this should be able to cope with a few seconds without
 * 		overflowing.
 *
 * xip_iprefetch()
 *
 *      Macro to fill instruction prefetch
 *	e.g. a series of nops:  asm volatile (".rep 8; nop; .endr");
 */

#include <asm/mtd-xip.h>

#ifndef xip_irqpending

#warning "missing IRQ and timer primitives for XIP MTD support"
#warning "some of the XIP MTD support code will be disabled"
#warning "your system will therefore be unresponsive when writing or erasing flash"

#define xip_irqpending()	(0)
#define xip_currtime()		(0)
#define xip_elapsed_since(x)	(0)

#endif

#ifndef xip_iprefetch
#define xip_iprefetch()		do { } while (0)
#endif

/*
 * xip_cpu_idle() is used when waiting for a delay equal or larger than
 * the system timer tick period.  This should put the CPU into idle mode
 * to save power and to be woken up only when some interrupts are pending.
 * This should not rely upon standard kernel code.
 */
#ifndef xip_cpu_idle
#define xip_cpu_idle()  do { } while (0)
#endif

#else

#define __xipram

#endif /* CONFIG_MTD_XIP */

#endif /* __LINUX_MTD_XIP_H__ */
Commit	Line	Data
1da177e4 LT	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.
1da177e4 LT	14	*/
	15
	16	#ifndef __LINUX_MTD_XIP_H__
	17	#define __LINUX_MTD_XIP_H__
	18
1da177e4 LT	19
	20	#ifdef CONFIG_MTD_XIP
	21
1da177e4 LT	22	/*
	23	* We really don't want gcc to guess anything.
	24	* We absolutely _need_ proper inlining.
	25	*/
	26	#include <linux/compiler.h>
	27
fb025873 NP	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
1da177e4 LT	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	*
25985edc	54	* note 1: conversion to usec can be approximated, as long as the
1da177e4 LT	55	* returned value is <= the real elapsed time.
	56	* note 2: this should be able to cope with a few seconds without
	57	* overflowing.
97f927a4 TG	58	*
97f927a4 TG	59	* xip_iprefetch()
61ecfa87	60	*
97f927a4	61	* Macro to fill instruction prefetch
61ecfa87	62	* e.g. a series of nops: asm volatile (".rep 8; nop; .endr");
1da177e4 LT	63	*/
1da177e4 LT	64
97f927a4	65	#include <asm/mtd-xip.h>
1da177e4	66
97f927a4	67	#ifndef xip_irqpending
1da177e4 LT	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
97f927a4 TG	79	#ifndef xip_iprefetch
	80	#define xip_iprefetch() do { } while (0)
	81	#endif
	82
1da177e4 LT	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.
97f927a4	87	* This should not rely upon standard kernel code.
1da177e4	88	*/
97f927a4	89	#ifndef xip_cpu_idle
1da177e4 LT	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__ */