u-boot/arch/arm/include/asm/arch-at91/at91_gpbr.h
Reinhard Meyer c7260d1539 AT91: add RTT and GPBR based RTC
Signed-off-by: Reinhard Meyer <u-boot@emk-elektronik.de>
2010-09-03 11:20:02 +02:00

45 lines
1.2 KiB
C

/*
* Copyright (C) 2010
* Reinhard Meyer, reinhard.meyer@emk-elektronik.de
*
* General Purpose Backup Registers
* Based on AT91SAM9XE datasheet
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#ifndef AT91_GPBR_H
#define AT91_GPBR_H
/*
* The Atmel AT91SAM9 series has a small resource of 4 nonvolatile
* 32 Bit registers (buffered by the Vbu power).
*
* Please consider carefully before using this resource for tasks
* that do not really need nonvolatile registers. Maybe you can
* store information in EEPROM or FLASH instead.
*
* However, if you use a GPBR please document its use here and
* reference the define in your code!
*
* known typical uses of the GPBRs:
* GPBR[0]: offset for RTT timekeeping (u-boot, kernel)
* GPBR[1]: unused
* GPBR[2]: unused
* GPBR[3]: bootcount (u-boot)
*/
#define AT91_GPBR_INDEX_TIMEOFF 0
#define AT91_GPBR_INDEX_BOOTCOUNT 3
#ifndef __ASSEMBLY__
typedef struct at91_gpbr {
u32 reg[4];
} at91_gpbr_t;
#endif /* __ASSEMBLY__ */
#endif