1 /*
2  * Copyright (C) 2010
3  * Reinhard Meyer, reinhard.meyer@emk-elektronik.de
4  *
5  * General Purpose Backup Registers
6  * Based on AT91SAM9XE datasheet
7  *
8  * SPDX-License-Identifier:	GPL-2.0+
9  */
10 
11 #ifndef AT91_GPBR_H
12 #define AT91_GPBR_H
13 
14 /*
15  * The Atmel AT91SAM9 series has a small resource of 4 nonvolatile
16  * 32 Bit registers (buffered by the Vbu power).
17  *
18  * Please consider carefully before using this resource for tasks
19  * that do not really need nonvolatile registers. Maybe you can
20  * store information in EEPROM or FLASH instead.
21  *
22  * However, if you use a GPBR please document its use here and
23  * reference the define in your code!
24  *
25  * known typical uses of the GPBRs:
26  * GPBR[0]: offset for RTT timekeeping (u-boot, kernel)
27  * GPBR[1]: unused
28  * GPBR[2]: unused
29  * GPBR[3]: bootcount (u-boot)
30  */
31 #define AT91_GPBR_INDEX_TIMEOFF 0
32 #define AT91_GPBR_INDEX_BOOTCOUNT 3
33 
34 #ifndef __ASSEMBLY__
35 
36 typedef struct at91_gpbr {
37 	u32 reg[4];
38 } at91_gpbr_t;
39 
40 #endif /* __ASSEMBLY__ */
41 
42 #endif
43