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AT91: add RTT and GPBR based RTC 

Signed-off-by: Reinhard Meyer <u-boot@emk-elektronik.de>
This commit is contained in:
Reinhard Meyer 2010-07-27 16:22:09 +02:00
parent 1592ef8596
commit c7260d1539
4 changed files with 182 additions and 0 deletions
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45
arch/arm/include/asm/arch-at91/at91_gpbr.h Normal file
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@ -0,0 +1,45 @@
/*
* 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

36
arch/arm/include/asm/arch-at91/at91_rtt.h Normal file
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/*
* Copyright (C) 2010
* Reinhard Meyer, reinhard.meyer@emk-elektronik.de
*
* Real-time Timer
* 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_RTT_H
#define AT91_RTT_H
#ifndef __ASSEMBLY__
typedef struct at91_rtt {
u32 mr; /* Mode Register RW 0x00008000 */
u32 ar; /* Alarm Register RW 0xFFFFFFFF */
u32 vr; /* Value Register RO 0x00000000 */
u32 sr; /* Status Register RO 0x00000000 */
} at91_rtt_t;
#endif /* __ASSEMBLY__ */
#define AT91_RTT_MR_RTPRES 0x0000ffff
#define AT91_RTT_MR_ALMIEN 0x00010000
#define AT91_RTT_RTTINCIEN 0x00020000
#define AT91_RTT_RTTRST 0x00040000
#define AT91_RTT_SR_ALMS 0x00000001
#define AT91_RTT_SR_RTTINC 0x00000002
#endif

1
drivers/rtc/Makefile
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@ -27,6 +27,7 @@ include $(TOPDIR)/config.mk
LIB = $(obj)librtc.a
COBJS-$(CONFIG_RTC_AT91SAM9_RTT) += at91sam9_rtt.o
COBJS-$(CONFIG_RTC_BFIN) += bfin_rtc.o
COBJS-y += date.o
COBJS-$(CONFIG_RTC_DS12887) += ds12887.o

100
drivers/rtc/at91sam9_rtt.c Normal file
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/*
* (C) Copyright 2010
* Reinhard Meyer, reinhard.meyer@emk-elektronik.de
*
* See file CREDITS for list of people who contributed to this
* project.
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
/*
* Date & Time support for the internal Real-time Timer
* of AT91SAM9260 and compatibles.
* Compatible with the LinuX rtc driver workaround:
* The RTT cannot be written to, but only reset.
* The actual time is the sum of RTT and one of
* the four GPBR registers.
*
* The at91sam9260 has 4 GPBR (0-3).
* For their typical use see at91_gpbr.h !
*
* make sure u-boot and kernel use the same GPBR !
*/
#include <common.h>
#include <command.h>
#include <rtc.h>
#include <asm/errno.h>
#include <asm/arch/hardware.h>
#include <asm/arch/io.h>
#include <asm/arch/at91_rtt.h>
#include <asm/arch/at91_gpbr.h>
#if defined(CONFIG_CMD_DATE)
int rtc_get (struct rtc_time *tmp)
{
at91_rtt_t *rtt = (at91_rtt_t *) AT91_RTT_BASE;
at91_gpbr_t *gpbr = (at91_gpbr_t *) AT91_GPR_BASE;
ulong tim;
ulong tim2;
ulong off;
do {
tim = readl(&rtt->vr);
tim2 = readl(&rtt->vr);
} while (tim!=tim2);
off = readl(&gpbr->reg[AT91_GPBR_INDEX_TIMEOFF]);
/* off==0 means time is invalid, but we ignore that */
to_tm (tim+off, tmp);
return 0;
}
int rtc_set (struct rtc_time *tmp)
{
at91_rtt_t *rtt = (at91_rtt_t *) AT91_RTT_BASE;
at91_gpbr_t *gpbr = (at91_gpbr_t *) AT91_GPR_BASE;
ulong tim;
tim = mktime (tmp->tm_year, tmp->tm_mon, tmp->tm_mday,
tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
/* clear alarm, set prescaler to 32768, clear counter */
writel(32768+AT91_RTT_RTTRST, &rtt->mr);
writel(~0, &rtt->ar);
writel(tim, &gpbr->reg[AT91_GPBR_INDEX_TIMEOFF]);
/* wait for counter clear to happen, takes less than a 1/32768th second */
while (readl(&rtt->vr) != 0)
;
return 0;
}
void rtc_reset (void)
{
at91_rtt_t *rtt = (at91_rtt_t *) AT91_RTT_BASE;
at91_gpbr_t *gpbr = (at91_gpbr_t *) AT91_GPR_BASE;
/* clear alarm, set prescaler to 32768, clear counter */
writel(32768+AT91_RTT_RTTRST, &rtt->mr);
writel(~0, &rtt->ar);
writel(0, &gpbr->reg[AT91_GPBR_INDEX_TIMEOFF]);
/* wait for counter clear to happen, takes less than a 1/32768th second */
while (readl(&rtt->vr) != 0)
;
}
#endif