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rtc: at91sam9 RTC support (RTT and/or RTC)
AT91sam9 RTC support, primarily in the form of an RTT-as-RTC driver that was
extracted from 2.6.23-at91 patch and updated:
- Relies on now-merged platform updates, which associate the RTT
hardware address with each RTT and use the "at91_rtt" name.
- RTC framework related fixes and cleanups, notably:
* removed now-needless suspend/resume clock offset logic
* alarm read/write now respects the "enabled" flag
* suspend always disables update irqs
* shutdown (and startup) disables all irqs
- Misc cleanup:
* use dev_*() messaging
* add comments
* remove globals,
* ... etc
- Don't force use of RTT0 and GPBR0. Either resource may need
to be used for other purposes (like NO_HZ support).
- Update "AT91RM9200 RTC" Kconfig to allow it on SAM9RL chips
(it has both RTT and RTC).
Driver binding uses bus_find_device() to avoid needing any kind of "timer
library" code when there's more than one RTT module. (This timer can be used
as an RTC, to support NO_HZ operation, or potentially for other stuff. The
choice is a per-system policy.)
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Michel Benoit <murpme@gmail.com>
Cc: Nicolas Ferre <nicolas.ferre@rfo.atmel.com>
Cc: Andrew Victor <linux@maxim.org.za>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Brownell
Linus Torvalds
parent
f618258ad8
commit
4cdf854f7d
@ -469,10 +469,47 @@ config RTC_DRV_AT32AP700X
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AT32AP700x family processors.
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config RTC_DRV_AT91RM9200
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tristate "AT91RM9200"
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depends on ARCH_AT91RM9200
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tristate "AT91RM9200 or AT91SAM9RL"
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depends on ARCH_AT91RM9200 || ARCH_AT91SAM9RL
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help
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Driver for the Atmel AT91RM9200's internal RTC (Realtime Clock).
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Driver for the internal RTC (Realtime Clock) module found on
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Atmel AT91RM9200's and AT91SAM9RL chips. On SAM9RL chips
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this is powered by the backup power supply.
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config RTC_DRV_AT91SAM9
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tristate "AT91SAM9x"
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depends on ARCH_AT91 && !(ARCH_AT91RM9200 || ARCH_AT91X40)
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help
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RTC driver for the Atmel AT91SAM9x internal RTT (Real Time Timer).
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These timers are powered by the backup power supply (such as a
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small coin cell battery), but do not need to be used as RTCs.
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(On AT91SAM9rl chips you probably want to use the dedicated RTC
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module and leave the RTT available for other uses.)
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config RTC_DRV_AT91SAM9_RTT
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int
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range 0 1
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default 0
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prompt "RTT module Number" if ARCH_AT91SAM9263
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depends on RTC_DRV_AT91SAM9
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help
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More than one RTT module is available. You can choose which
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one will be used as an RTC. The default of zero is normally
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OK to use, though some systems use that for non-RTC purposes.
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config RTC_DRV_AT91SAM9_GPBR
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int
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range 0 3 if !ARCH_AT91SAM9263
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range 0 15 if ARCH_AT91SAM9263
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default 0
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prompt "Backup Register Number"
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depends on RTC_DRV_AT91SAM9
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help
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The RTC driver needs to use one of the General Purpose Backup
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Registers (GPBRs) as well as the RTT. You can choose which one
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will be used. The default of zero is normally OK to use, but
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on some systems other software needs to use that register.
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config RTC_DRV_BFIN
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tristate "Blackfin On-Chip RTC"
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@ -19,6 +19,7 @@ rtc-core-$(CONFIG_RTC_INTF_SYSFS) += rtc-sysfs.o
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obj-$(CONFIG_RTC_DRV_AT32AP700X)+= rtc-at32ap700x.o
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obj-$(CONFIG_RTC_DRV_AT91RM9200)+= rtc-at91rm9200.o
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obj-$(CONFIG_RTC_DRV_AT91SAM9) += rtc-at91sam9.o
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obj-$(CONFIG_RTC_DRV_BFIN) += rtc-bfin.o
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obj-$(CONFIG_RTC_DRV_CMOS) += rtc-cmos.o
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obj-$(CONFIG_RTC_DRV_DS1216) += rtc-ds1216.o
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520
drivers/rtc/rtc-at91sam9.c
Normal file
520
drivers/rtc/rtc-at91sam9.c
Normal file
@ -0,0 +1,520 @@
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/*
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* "RTT as Real Time Clock" driver for AT91SAM9 SoC family
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*
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* (C) 2007 Michel Benoit
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*
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* Based on rtc-at91rm9200.c by Rick Bronson
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/platform_device.h>
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#include <linux/time.h>
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#include <linux/rtc.h>
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#include <linux/interrupt.h>
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#include <linux/ioctl.h>
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#include <asm/mach/time.h>
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#include <asm/arch/board.h>
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#include <asm/arch/at91_rtt.h>
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/*
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* This driver uses two configurable hardware resources that live in the
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* AT91SAM9 backup power domain (intended to be powered at all times)
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* to implement the Real Time Clock interfaces
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*
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* - A "Real-time Timer" (RTT) counts up in seconds from a base time.
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* We can't assign the counter value (CRTV) ... but we can reset it.
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*
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* - One of the "General Purpose Backup Registers" (GPBRs) holds the
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* base time, normally an offset from the beginning of the POSIX
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* epoch (1970-Jan-1 00:00:00 UTC). Some systems also include the
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* local timezone's offset.
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*
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* The RTC's value is the RTT counter plus that offset. The RTC's alarm
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* is likewise a base (ALMV) plus that offset.
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*
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* Not all RTTs will be used as RTCs; some systems have multiple RTTs to
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* choose from, or a "real" RTC module. All systems have multiple GPBR
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* registers available, likewise usable for more than "RTC" support.
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*/
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/*
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* We store ALARM_DISABLED in ALMV to record that no alarm is set.
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* It's also the reset value for that field.
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*/
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#define ALARM_DISABLED ((u32)~0)
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struct sam9_rtc {
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void __iomem *rtt;
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struct rtc_device *rtcdev;
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u32 imr;
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};
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#define rtt_readl(rtc, field) \
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__raw_readl((rtc)->rtt + AT91_RTT_ ## field)
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#define rtt_writel(rtc, field, val) \
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__raw_writel((val), (rtc)->rtt + AT91_RTT_ ## field)
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#define gpbr_readl(rtc) \
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at91_sys_read(AT91_GPBR + 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR)
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#define gpbr_writel(rtc, val) \
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at91_sys_write(AT91_GPBR + 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR, (val))
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/*
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* Read current time and date in RTC
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*/
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static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm)
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{
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struct sam9_rtc *rtc = dev_get_drvdata(dev);
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u32 secs, secs2;
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u32 offset;
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/* read current time offset */
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offset = gpbr_readl(rtc);
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if (offset == 0)
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return -EILSEQ;
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/* reread the counter to help sync the two clock domains */
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secs = rtt_readl(rtc, VR);
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secs2 = rtt_readl(rtc, VR);
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if (secs != secs2)
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secs = rtt_readl(rtc, VR);
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rtc_time_to_tm(offset + secs, tm);
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dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readtime",
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1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
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tm->tm_hour, tm->tm_min, tm->tm_sec);
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return 0;
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}
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/*
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* Set current time and date in RTC
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*/
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static int at91_rtc_settime(struct device *dev, struct rtc_time *tm)
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{
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struct sam9_rtc *rtc = dev_get_drvdata(dev);
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int err;
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u32 offset, alarm, mr;
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unsigned long secs;
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dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "settime",
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1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
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tm->tm_hour, tm->tm_min, tm->tm_sec);
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err = rtc_tm_to_time(tm, &secs);
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if (err != 0)
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return err;
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mr = rtt_readl(rtc, MR);
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/* disable interrupts */
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rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN));
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/* read current time offset */
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offset = gpbr_readl(rtc);
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/* store the new base time in a battery backup register */
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secs += 1;
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gpbr_writel(rtc, secs);
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/* adjust the alarm time for the new base */
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alarm = rtt_readl(rtc, AR);
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if (alarm != ALARM_DISABLED) {
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if (offset > secs) {
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/* time jumped backwards, increase time until alarm */
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alarm += (offset - secs);
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} else if ((alarm + offset) > secs) {
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/* time jumped forwards, decrease time until alarm */
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alarm -= (secs - offset);
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} else {
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/* time jumped past the alarm, disable alarm */
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alarm = ALARM_DISABLED;
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mr &= ~AT91_RTT_ALMIEN;
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}
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rtt_writel(rtc, AR, alarm);
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}
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/* reset the timer, and re-enable interrupts */
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rtt_writel(rtc, MR, mr | AT91_RTT_RTTRST);
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return 0;
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}
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static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
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{
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struct sam9_rtc *rtc = dev_get_drvdata(dev);
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struct rtc_time *tm = &alrm->time;
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u32 alarm = rtt_readl(rtc, AR);
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u32 offset;
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offset = gpbr_readl(rtc);
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if (offset == 0)
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return -EILSEQ;
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memset(alrm, 0, sizeof(alrm));
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if (alarm != ALARM_DISABLED && offset != 0) {
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rtc_time_to_tm(offset + alarm, tm);
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dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readalarm",
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1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
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tm->tm_hour, tm->tm_min, tm->tm_sec);
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if (rtt_readl(rtc, MR) & AT91_RTT_ALMIEN)
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alrm->enabled = 1;
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}
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return 0;
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}
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static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
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{
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struct sam9_rtc *rtc = dev_get_drvdata(dev);
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struct rtc_time *tm = &alrm->time;
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unsigned long secs;
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u32 offset;
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u32 mr;
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int err;
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err = rtc_tm_to_time(tm, &secs);
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if (err != 0)
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return err;
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offset = gpbr_readl(rtc);
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if (offset == 0) {
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/* time is not set */
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return -EILSEQ;
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}
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mr = rtt_readl(rtc, MR);
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rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);
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/* alarm in the past? finish and leave disabled */
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if (secs <= offset) {
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rtt_writel(rtc, AR, ALARM_DISABLED);
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return 0;
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}
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/* else set alarm and maybe enable it */
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rtt_writel(rtc, AR, secs - offset);
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if (alrm->enabled)
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rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN);
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dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "setalarm",
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tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour,
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tm->tm_min, tm->tm_sec);
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return 0;
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}
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/*
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* Handle commands from user-space
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*/
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static int at91_rtc_ioctl(struct device *dev, unsigned int cmd,
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unsigned long arg)
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{
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struct sam9_rtc *rtc = dev_get_drvdata(dev);
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int ret = 0;
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u32 mr = rtt_readl(rtc, MR);
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dev_dbg(dev, "ioctl: cmd=%08x, arg=%08lx, mr %08x\n", cmd, arg, mr);
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switch (cmd) {
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case RTC_AIE_OFF: /* alarm off */
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rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);
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break;
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case RTC_AIE_ON: /* alarm on */
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rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN);
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break;
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case RTC_UIE_OFF: /* update off */
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rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN);
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break;
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case RTC_UIE_ON: /* update on */
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rtt_writel(rtc, MR, mr | AT91_RTT_RTTINCIEN);
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break;
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default:
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ret = -ENOIOCTLCMD;
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break;
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}
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return ret;
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}
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/*
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* Provide additional RTC information in /proc/driver/rtc
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*/
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static int at91_rtc_proc(struct device *dev, struct seq_file *seq)
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{
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struct sam9_rtc *rtc = dev_get_drvdata(dev);
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u32 mr = mr = rtt_readl(rtc, MR);
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seq_printf(seq, "update_IRQ\t: %s\n",
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(mr & AT91_RTT_RTTINCIEN) ? "yes" : "no");
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return 0;
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}
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/*
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* IRQ handler for the RTC
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*/
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static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc)
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{
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struct sam9_rtc *rtc = _rtc;
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u32 sr, mr;
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unsigned long events = 0;
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/* Shared interrupt may be for another device. Note: reading
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* SR clears it, so we must only read it in this irq handler!
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*/
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mr = rtt_readl(rtc, MR) & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
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sr = rtt_readl(rtc, SR) & mr;
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if (!sr)
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return IRQ_NONE;
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/* alarm status */
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if (sr & AT91_RTT_ALMS)
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events |= (RTC_AF | RTC_IRQF);
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/* timer update/increment */
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if (sr & AT91_RTT_RTTINC)
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events |= (RTC_UF | RTC_IRQF);
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rtc_update_irq(rtc->rtcdev, 1, events);
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pr_debug("%s: num=%ld, events=0x%02lx\n", __FUNCTION__,
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events >> 8, events & 0x000000FF);
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return IRQ_HANDLED;
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}
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static const struct rtc_class_ops at91_rtc_ops = {
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.ioctl = at91_rtc_ioctl,
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.read_time = at91_rtc_readtime,
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.set_time = at91_rtc_settime,
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.read_alarm = at91_rtc_readalarm,
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.set_alarm = at91_rtc_setalarm,
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.proc = at91_rtc_proc,
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};
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/*
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* Initialize and install RTC driver
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*/
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static int __init at91_rtc_probe(struct platform_device *pdev)
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{
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struct resource *r;
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struct sam9_rtc *rtc;
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int ret;
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u32 mr;
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r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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if (!r)
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return -ENODEV;
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rtc = kzalloc(sizeof *rtc, GFP_KERNEL);
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if (!rtc)
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return -ENOMEM;
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platform_set_drvdata(pdev, rtc);
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rtc->rtt = (void __force __iomem *) (AT91_VA_BASE_SYS - AT91_BASE_SYS);
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rtc->rtt += r->start;
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mr = rtt_readl(rtc, MR);
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/* unless RTT is counting at 1 Hz, re-initialize it */
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if ((mr & AT91_RTT_RTPRES) != AT91_SLOW_CLOCK) {
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mr = AT91_RTT_RTTRST | (AT91_SLOW_CLOCK & AT91_RTT_RTPRES);
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gpbr_writel(rtc, 0);
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}
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/* disable all interrupts (same as on shutdown path) */
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mr &= ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
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rtt_writel(rtc, MR, mr);
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rtc->rtcdev = rtc_device_register(pdev->name, &pdev->dev,
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&at91_rtc_ops, THIS_MODULE);
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if (IS_ERR(rtc->rtcdev)) {
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ret = PTR_ERR(rtc->rtcdev);
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goto fail;
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}
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/* register irq handler after we know what name we'll use */
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ret = request_irq(AT91_ID_SYS, at91_rtc_interrupt,
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IRQF_DISABLED | IRQF_SHARED,
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rtc->rtcdev->dev.bus_id, rtc);
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if (ret) {
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dev_dbg(&pdev->dev, "can't share IRQ %d?\n", AT91_ID_SYS);
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rtc_device_unregister(rtc->rtcdev);
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goto fail;
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}
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/* NOTE: sam9260 rev A silicon has a ROM bug which resets the
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* RTT on at least some reboots. If you have that chip, you must
|
||||
* initialize the time from some external source like a GPS, wall
|
||||
* clock, discrete RTC, etc
|
||||
*/
|
||||
|
||||
if (gpbr_readl(rtc) == 0)
|
||||
dev_warn(&pdev->dev, "%s: SET TIME!\n",
|
||||
rtc->rtcdev->dev.bus_id);
|
||||
|
||||
return 0;
|
||||
|
||||
fail:
|
||||
platform_set_drvdata(pdev, NULL);
|
||||
kfree(rtc);
|
||||
return ret;
|
||||
}
|
||||
|
||||
/*
|
||||
* Disable and remove the RTC driver
|
||||
*/
|
||||
static int __exit at91_rtc_remove(struct platform_device *pdev)
|
||||
{
|
||||
struct sam9_rtc *rtc = platform_get_drvdata(pdev);
|
||||
u32 mr = rtt_readl(rtc, MR);
|
||||
|
||||
/* disable all interrupts */
|
||||
rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN));
|
||||
free_irq(AT91_ID_SYS, rtc);
|
||||
|
||||
rtc_device_unregister(rtc->rtcdev);
|
||||
|
||||
platform_set_drvdata(pdev, NULL);
|
||||
kfree(rtc);
|
||||
return 0;
|
||||
}
|
||||
|
||||
static void at91_rtc_shutdown(struct platform_device *pdev)
|
||||
{
|
||||
struct sam9_rtc *rtc = platform_get_drvdata(pdev);
|
||||
u32 mr = rtt_readl(rtc, MR);
|
||||
|
||||
rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
|
||||
rtt_writel(rtc, MR, mr & ~rtc->imr);
|
||||
}
|
||||
|
||||
#ifdef CONFIG_PM
|
||||
|
||||
/* AT91SAM9 RTC Power management control */
|
||||
|
||||
static int at91_rtc_suspend(struct platform_device *pdev,
|
||||
pm_message_t state)
|
||||
{
|
||||
struct sam9_rtc *rtc = platform_get_drvdata(pdev);
|
||||
u32 mr = rtt_readl(rtc, MR);
|
||||
|
||||
/*
|
||||
* This IRQ is shared with DBGU and other hardware which isn't
|
||||
* necessarily a wakeup event source.
|
||||
*/
|
||||
rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
|
||||
if (rtc->imr) {
|
||||
if (device_may_wakeup(&pdev->dev) && (mr & AT91_RTT_ALMIEN)) {
|
||||
enable_irq_wake(AT91_ID_SYS);
|
||||
/* don't let RTTINC cause wakeups */
|
||||
if (mr & AT91_RTT_RTTINCIEN)
|
||||
rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN);
|
||||
} else
|
||||
rtt_writel(rtc, MR, mr & ~rtc->imr);
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static int at91_rtc_resume(struct platform_device *pdev)
|
||||
{
|
||||
struct sam9_rtc *rtc = platform_get_drvdata(pdev);
|
||||
u32 mr;
|
||||
|
||||
if (rtc->imr) {
|
||||
if (device_may_wakeup(&pdev->dev))
|
||||
disable_irq_wake(AT91_ID_SYS);
|
||||
mr = rtt_readl(rtc, MR);
|
||||
rtt_writel(rtc, MR, mr | rtc->imr);
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
#else
|
||||
#define at91_rtc_suspend NULL
|
||||
#define at91_rtc_resume NULL
|
||||
#endif
|
||||
|
||||
static struct platform_driver at91_rtc_driver = {
|
||||
.driver.name = "rtc-at91sam9",
|
||||
.driver.owner = THIS_MODULE,
|
||||
.remove = __exit_p(at91_rtc_remove),
|
||||
.shutdown = at91_rtc_shutdown,
|
||||
.suspend = at91_rtc_suspend,
|
||||
.resume = at91_rtc_resume,
|
||||
};
|
||||
|
||||
/* Chips can have more than one RTT module, and they can be used for more
|
||||
* than just RTCs. So we can't just register as "the" RTT driver.
|
||||
*
|
||||
* A normal approach in such cases is to create a library to allocate and
|
||||
* free the modules. Here we just use bus_find_device() as like such a
|
||||
* library, binding directly ... no runtime "library" footprint is needed.
|
||||
*/
|
||||
static int __init at91_rtc_match(struct device *dev, void *v)
|
||||
{
|
||||
struct platform_device *pdev = to_platform_device(dev);
|
||||
int ret;
|
||||
|
||||
/* continue searching if this isn't the RTT we need */
|
||||
if (strcmp("at91_rtt", pdev->name) != 0
|
||||
|| pdev->id != CONFIG_RTC_DRV_AT91SAM9_RTT)
|
||||
goto fail;
|
||||
|
||||
/* else we found it ... but fail unless we can bind to the RTC driver */
|
||||
if (dev->driver) {
|
||||
dev_dbg(dev, "busy, can't use as RTC!\n");
|
||||
goto fail;
|
||||
}
|
||||
dev->driver = &at91_rtc_driver.driver;
|
||||
if (device_attach(dev) == 0) {
|
||||
dev_dbg(dev, "can't attach RTC!\n");
|
||||
goto fail;
|
||||
}
|
||||
ret = at91_rtc_probe(pdev);
|
||||
if (ret == 0)
|
||||
return true;
|
||||
|
||||
dev_dbg(dev, "RTC probe err %d!\n", ret);
|
||||
fail:
|
||||
return false;
|
||||
}
|
||||
|
||||
static int __init at91_rtc_init(void)
|
||||
{
|
||||
int status;
|
||||
struct device *rtc;
|
||||
|
||||
status = platform_driver_register(&at91_rtc_driver);
|
||||
if (status)
|
||||
return status;
|
||||
rtc = bus_find_device(&platform_bus_type, NULL,
|
||||
NULL, at91_rtc_match);
|
||||
if (!rtc)
|
||||
platform_driver_unregister(&at91_rtc_driver);
|
||||
return rtc ? 0 : -ENODEV;
|
||||
}
|
||||
module_init(at91_rtc_init);
|
||||
|
||||
static void __exit at91_rtc_exit(void)
|
||||
{
|
||||
platform_driver_unregister(&at91_rtc_driver);
|
||||
}
|
||||
module_exit(at91_rtc_exit);
|
||||
|
||||
|
||||
MODULE_AUTHOR("Michel Benoit");
|
||||
MODULE_DESCRIPTION("RTC driver for Atmel AT91SAM9x");
|
||||
MODULE_LICENSE("GPL");
|
||||
Loading…
Reference in New Issue
Block a user