1 /* SPDX-License-Identifier: GPL-2.0+ */ 2 /* 3 * Copyright (C) 2010 4 * Reinhard Meyer, reinhard.meyer@emk-elektronik.de 5 * 6 * General Purpose Backup Registers 7 * Based on AT91SAM9XE datasheet 8 */ 9 10 #ifndef AT91_GPBR_H 11 #define AT91_GPBR_H 12 13 /* 14 * The Atmel AT91SAM9 series has a small resource of 4 nonvolatile 15 * 32 Bit registers (buffered by the Vbu power). 16 * 17 * Please consider carefully before using this resource for tasks 18 * that do not really need nonvolatile registers. Maybe you can 19 * store information in EEPROM or FLASH instead. 20 * 21 * However, if you use a GPBR please document its use here and 22 * reference the define in your code! 23 * 24 * known typical uses of the GPBRs: 25 * GPBR[0]: offset for RTT timekeeping (u-boot, kernel) 26 * GPBR[1]: unused 27 * GPBR[2]: unused 28 * GPBR[3]: bootcount (u-boot) 29 */ 30 #define AT91_GPBR_INDEX_TIMEOFF 0 31 #define AT91_GPBR_INDEX_BOOTCOUNT 3 32 33 #ifndef __ASSEMBLY__ 34 35 typedef struct at91_gpbr { 36 u32 reg[4]; 37 } at91_gpbr_t; 38 39 #endif /* __ASSEMBLY__ */ 40 41 #endif 42