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git.ipfire.org Git - people/ms/u-boot.git/blob - drivers/rtc/at91sam9_rtt.c
3 * Reinhard Meyer, reinhard.meyer@emk-elektronik.de
5 * SPDX-License-Identifier: GPL-2.0+
9 * Date & Time support for the internal Real-time Timer
10 * of AT91SAM9260 and compatibles.
11 * Compatible with the LinuX rtc driver workaround:
12 * The RTT cannot be written to, but only reset.
13 * The actual time is the sum of RTT and one of
14 * the four GPBR registers.
16 * The at91sam9260 has 4 GPBR (0-3).
17 * For their typical use see at91_gpbr.h !
19 * make sure u-boot and kernel use the same GPBR !
26 #include <linux/errno.h>
27 #include <asm/arch/hardware.h>
28 #include <asm/arch/at91_rtt.h>
29 #include <asm/arch/at91_gpbr.h>
31 #if defined(CONFIG_CMD_DATE)
33 int rtc_get (struct rtc_time
*tmp
)
35 at91_rtt_t
*rtt
= (at91_rtt_t
*) ATMEL_BASE_RTT
;
36 at91_gpbr_t
*gpbr
= (at91_gpbr_t
*) ATMEL_BASE_GPBR
;
42 tim
= readl(&rtt
->vr
);
43 tim2
= readl(&rtt
->vr
);
45 off
= readl(&gpbr
->reg
[AT91_GPBR_INDEX_TIMEOFF
]);
46 /* off==0 means time is invalid, but we ignore that */
47 rtc_to_tm(tim
+off
, tmp
);
51 int rtc_set (struct rtc_time
*tmp
)
53 at91_rtt_t
*rtt
= (at91_rtt_t
*) ATMEL_BASE_RTT
;
54 at91_gpbr_t
*gpbr
= (at91_gpbr_t
*) ATMEL_BASE_GPBR
;
57 tim
= rtc_mktime(tmp
);
59 /* clear alarm, set prescaler to 32768, clear counter */
60 writel(32768+AT91_RTT_RTTRST
, &rtt
->mr
);
62 writel(tim
, &gpbr
->reg
[AT91_GPBR_INDEX_TIMEOFF
]);
63 /* wait for counter clear to happen, takes less than a 1/32768th second */
64 while (readl(&rtt
->vr
) != 0)
71 at91_rtt_t
*rtt
= (at91_rtt_t
*) ATMEL_BASE_RTT
;
72 at91_gpbr_t
*gpbr
= (at91_gpbr_t
*) ATMEL_BASE_GPBR
;
74 /* clear alarm, set prescaler to 32768, clear counter */
75 writel(32768+AT91_RTT_RTTRST
, &rtt
->mr
);
77 writel(0, &gpbr
->reg
[AT91_GPBR_INDEX_TIMEOFF
]);
78 /* wait for counter clear to happen, takes less than a 1/32768th second */
79 while (readl(&rtt
->vr
) != 0)