[U-Boot] [PATCH 1/1] at91sam9x: driver to use the internal RTT as RTC

[Tom <Tom.Rix@windriver.com>]

Alexander Holler wrote:
> Based on the linux driver.
> 

AT91 is moving away from legacy register access to accessing registers
through structures.  Please convert to this change to the new at91
register access through structures.
See doc/README.at91-soc

> Signed-off-by: Alexander Holler <holler@ahsoftware.de>
> ---
>  README                     |    1 +
>  drivers/rtc/Makefile       |    1 +
>  drivers/rtc/at91sam9-rtc.c |  162 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 164 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/rtc/at91sam9-rtc.c
> 
> diff --git a/README b/README
> index 940b507..afe2aa6 100644
> --- a/README
> +++ b/README
> @@ -733,6 +733,7 @@ The following options need to be configured:
>  		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
>  		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
>  		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
> +		CONFIG_RTC_AT91SAM9	- use internal RTT of AT91SAM9x
>  
>  		Note that if the RTC uses I2C, then the I2C interface
>  		must also be configured. See I2C Support, below.
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 772a49a..4a48231 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -62,6 +62,7 @@ COBJS-$(CONFIG_RTC_RX8025) += rx8025.o
>  COBJS-$(CONFIG_RTC_S3C24X0) += s3c24x0_rtc.o
>  COBJS-$(CONFIG_RTC_S3C44B0) += s3c44b0_rtc.o
>  COBJS-$(CONFIG_RTC_X1205) += x1205.o
> +COBJS-$(CONFIG_RTC_AT91SAM9) += at91sam9-rtc.o
>  
>  COBJS	:= $(sort $(COBJS-y))
>  SRCS	:= $(COBJS:.o=.c)
> diff --git a/drivers/rtc/at91sam9-rtc.c b/drivers/rtc/at91sam9-rtc.c
> new file mode 100644
> index 0000000..d0a263a
> --- /dev/null
> +++ b/drivers/rtc/at91sam9-rtc.c
> @@ -0,0 +1,162 @@
> +/*
> + * "RTT as Real Time Clock" driver for AT91SAM9 SoC family
> + *
> + * (C) Copyright 2010
> + * Alexander Holler <holler@ahsoftware.de>
> + *
> + * Based on rtc-at91sam9.c from Michel Benoit
> + * Based on rtc-at91rm9200.c by Rick Bronson
> + *
> + * 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
> + */
> +
> +/*
> + * This driver uses two configurable hardware resources that live in the
> + * AT91SAM9 backup power domain (intended to be powered at all times)
> + * to implement the Real Time Clock interfaces
> + *
> + *  - A "Real-time Timer" (RTT) counts up in seconds from a base time.
> + *    We can't assign the counter value (CRTV) ... but we can reset it.
> + *
> + *  - One of the "General Purpose Backup Registers" (GPBRs) holds the
> + *    base time, normally an offset from the beginning of the POSIX
> + *    epoch (1970-Jan-1 00:00:00 UTC).  Some systems also include the
> + *    local timezone's offset.
> + *
> + * The RTC's value is the RTT counter plus that offset.  The RTC's alarm
> + * is likewise a base (ALMV) plus that offset.
> + *
> + * Not all RTTs will be used as RTCs; some systems have multiple RTTs to
> + * choose from, or a "real" RTC module.  All systems have multiple GPBR
> + * registers available, likewise usable for more than "RTC" support.
> + *
> + * In addition to CONFIG_CMD_DATE these additional defines must be set:
> + *
> + * #define CONFIG_RTC_AT91SAM9
> + * #define CONFIG_RTC_AT91SAM9_RTT AT91_RTT0_BASE
> + * #define CONFIG_RTC_AT91SAM9_GPBR 0
> + *
> + */
> +#include <common.h>
> +#include <command.h>
> +#include <asm/arch/io.h>
> +#include <asm/arch/hardware.h>
> +#include <rtc.h>
> +
> +#if defined(CONFIG_CMD_DATE)
> +
> +#undef RTC_DEBUG
> +
> +#ifdef RTC_DEBUG
> +#  define DPRINTF(x,args...)	printf("at91sam9-rtc: " x , ##args)
> +#else
> +#  define DPRINTF(x,args...)
> +#endif

Could this be converted to use the generic 'debug' macro in include/common.h?

> +
> +/* Defines copied from linux/arch/arm/mach-at91/include/mach/at91_rtt.h */
> +#define AT91_RTT_MR		0x00		/* Real-time Mode Register */
> +#define AT91_RTT_AR		0x04		/* Real-time Alarm Register */
> +#define AT91_RTT_VR		0x08		/* Real-time Value Register */
> +#define AT91_RTT_RTPRES		(0xffff << 0)	/* Real-time Timer Prescaler Value */
> +#define AT91_RTT_ALMIEN		(1 << 16)	/* Alarm Interrupt Enable */
> +#define AT91_RTT_RTTINCIEN	(1 << 17)	/* Real Time Timer Increment Interrupt Enable */
> +#define AT91_RTT_RTTRST		(1 << 18)	/* Real Time Timer Restart */
> +
> +/*
> + * We store ALARM_DISABLED in ALMV to record that no alarm is set.
> + * It's also the reset value for that field.
> + */
> +#define ALARM_DISABLED	((u32)~0)
> +
> +#define rtt_readl(field) \
> +	readl(CONFIG_RTC_AT91SAM9_RTT + AT91_RTT_ ## field)
> +#define rtt_writel(field, val) \
> +	writel((val), CONFIG_RTC_AT91SAM9_RTT + AT91_RTT_ ## field)
> +#define gpbr_readl() \
> +	readl(AT91_GPBR_BASE + 4 * CONFIG_RTC_AT91SAM9_GPBR)
> +#define gpbr_writel(val) \
> +	writel((val), AT91_GPBR_BASE + 4 * CONFIG_RTC_AT91SAM9_GPBR)
> +
> +void rtc_reset(void)
> +{
> +	u32 mr = rtt_readl(MR);
> +
> +	/* disable interrupts and reset prescaler */
> +	mr &= ~(AT91_RTT_RTPRES | AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
> +	mr |= AT91_SLOW_CLOCK & AT91_RTT_RTPRES;
> +	rtt_writel(MR, mr);
> +
> +	/* Clear values */
> +	gpbr_writel(0);
> +	rtt_writel(AR, ALARM_DISABLED);
> +
> +	/* reset and start the timer */
> +	rtt_writel(MR, mr | AT91_RTT_RTTRST);
> +
> +	DPRINTF("Reset DATE\n");
> +}
> +
> +int rtc_get(struct rtc_time *tmp)
> +{

Change parameter name to something more descriptive.
'tmp' implies used locally and this value is passed back.
Maybe 'tm' as to_tmp(.., struct rtc_time *tm) ?

> +	u32 secs, secs2;
> +	u32 offset;
> +
> +	u32 mr = rtt_readl(MR);
> +	if ((mr & AT91_RTT_RTPRES) != AT91_SLOW_CLOCK) {
> +		printf("Clock not initialized, use date (re)set!\n");
> +		return 0;
> +	}
> +
> +	/* read current time offset */
> +	offset = gpbr_readl();
> +	if (offset == 0) {
> +		printf("Time not set!\n");
> +		return 0;
> +	}
> +
> +	/* reread the counter to help sync the two clock domains */
> +	secs = rtt_readl(VR);
> +	secs2 = rtt_readl(VR);
> +	if (secs != secs2)
> +		secs = rtt_readl(VR);
> +
> +	to_tm (offset+secs, tmp);
> +
> +	DPRINTF("Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
> +		tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
> +		tmp->tm_hour, tmp->tm_min, tmp->tm_sec );
> +
> +	return 0;
> +}
> +
> +int rtc_set(struct rtc_time *tmp)
> +{

Change tmp here too.

> +	u32 secs = mktime(tmp->tm_year, tmp->tm_mon, tmp->tm_mday,
> +			tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
> +	rtc_reset();
> +	gpbr_writel(secs);
> +
> +	DPRINTF("Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
> +		tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
> +		tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
> +
> +	return 0;
> +}
> +
> +#endif /* CONFIG_CMD_DATE */

Tom