From 095b9d546f8fdac335989bd3d60405ff3af40ee9 Mon Sep 17 00:00:00 2001 From: Mike Frysinger Date: Wed, 6 Feb 2008 01:38:51 -0800 Subject: Blackfin RTC driver: convert sync wait to use the irq write complete notice - thus clearing out the need for spin locks - add a small optimization for reading of the rtc field Signed-off-by: Mike Frysinger Signed-off-by: Bryan Wu Acked-by: Alessandro Zummo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/rtc/rtc-bfin.c | 249 +++++++++++++++++++++++++++---------------------- 1 file changed, 136 insertions(+), 113 deletions(-) (limited to 'drivers/rtc/rtc-bfin.c') diff --git a/drivers/rtc/rtc-bfin.c b/drivers/rtc/rtc-bfin.c index 69810a2fc43..d90ba860d21 100644 --- a/drivers/rtc/rtc-bfin.c +++ b/drivers/rtc/rtc-bfin.c @@ -1,6 +1,6 @@ /* * Blackfin On-Chip Real Time Clock Driver - * Supports BF53[123]/BF53[467]/BF54[2489] + * Supports BF52[257]/BF53[123]/BF53[467]/BF54[24789] * * Copyright 2004-2007 Analog Devices Inc. * @@ -32,16 +32,16 @@ * writes to clear status registers complete immediately. */ -#include -#include #include -#include +#include +#include #include +#include +#include +#include #include +#include #include -#include -#include -#include #include @@ -50,7 +50,7 @@ struct bfin_rtc { struct rtc_device *rtc_dev; struct rtc_time rtc_alarm; - spinlock_t lock; + u16 rtc_wrote_regs; }; /* Bit values for the ISTAT / ICTL registers */ @@ -96,7 +96,10 @@ static inline void rtc_bfin_to_tm(u32 rtc_bfin, struct rtc_time *tm) rtc_time_to_tm(rtc_bfin_to_time(rtc_bfin), tm); } -/* Wait for the previous write to a RTC register to complete. +/** + * bfin_rtc_sync_pending - make sure pending writes have complete + * + * Wait for the previous write to a RTC register to complete. * Unfortunately, we can't sleep here as that introduces a race condition when * turning on interrupt events. Consider this: * - process sets alarm @@ -117,64 +120,102 @@ static inline void rtc_bfin_to_tm(u32 rtc_bfin, struct rtc_time *tm) * inc rate for all RTC registers from 1HZ to 32.768kHZ ... * - use the write complete IRQ */ -static void rtc_bfin_sync_pending(void) +/* +static void bfin_rtc_sync_pending_polled(void) { - while (!(bfin_read_RTC_ISTAT() & RTC_ISTAT_WRITE_COMPLETE)) { + while (!(bfin_read_RTC_ISTAT() & RTC_ISTAT_WRITE_COMPLETE)) if (!(bfin_read_RTC_ISTAT() & RTC_ISTAT_WRITE_PENDING)) break; - } bfin_write_RTC_ISTAT(RTC_ISTAT_WRITE_COMPLETE); } +*/ +static DECLARE_COMPLETION(bfin_write_complete); +static void bfin_rtc_sync_pending(struct device *dev) +{ + dev_dbg_stamp(dev); + while (bfin_read_RTC_ISTAT() & RTC_ISTAT_WRITE_PENDING) + wait_for_completion_timeout(&bfin_write_complete, HZ * 5); + dev_dbg_stamp(dev); +} -static void rtc_bfin_reset(struct device *dev) +/** + * bfin_rtc_reset - set RTC to sane/known state + * + * Initialize the RTC. Enable pre-scaler to scale RTC clock + * to 1Hz and clear interrupt/status registers. + */ +static void bfin_rtc_reset(struct device *dev) { struct bfin_rtc *rtc = dev_get_drvdata(dev); - /* Initialize the RTC. Enable pre-scaler to scale RTC clock - * to 1Hz and clear interrupt/status registers. */ - spin_lock_irq(&rtc->lock); - rtc_bfin_sync_pending(); + dev_dbg_stamp(dev); + bfin_rtc_sync_pending(dev); bfin_write_RTC_PREN(0x1); - bfin_write_RTC_ICTL(0); + bfin_write_RTC_ICTL(RTC_ISTAT_WRITE_COMPLETE); bfin_write_RTC_SWCNT(0); bfin_write_RTC_ALARM(0); bfin_write_RTC_ISTAT(0xFFFF); - spin_unlock_irq(&rtc->lock); + rtc->rtc_wrote_regs = 0; } +/** + * bfin_rtc_interrupt - handle interrupt from RTC + * + * Since we handle all RTC events here, we have to make sure the requested + * interrupt is enabled (in RTC_ICTL) as the event status register (RTC_ISTAT) + * always gets updated regardless of the interrupt being enabled. So when one + * even we care about (e.g. stopwatch) goes off, we don't want to turn around + * and say that other events have happened as well (e.g. second). We do not + * have to worry about pending writes to the RTC_ICTL register as interrupts + * only fire if they are enabled in the RTC_ICTL register. + */ static irqreturn_t bfin_rtc_interrupt(int irq, void *dev_id) { struct device *dev = dev_id; struct bfin_rtc *rtc = dev_get_drvdata(dev); unsigned long events = 0; - u16 rtc_istat; + bool write_complete = false; + u16 rtc_istat, rtc_ictl; dev_dbg_stamp(dev); - spin_lock_irq(&rtc->lock); - rtc_istat = bfin_read_RTC_ISTAT(); + rtc_ictl = bfin_read_RTC_ICTL(); - if (rtc_istat & (RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY)) { - bfin_write_RTC_ISTAT(RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY); - events |= RTC_AF | RTC_IRQF; + if (rtc_istat & RTC_ISTAT_WRITE_COMPLETE) { + bfin_write_RTC_ISTAT(RTC_ISTAT_WRITE_COMPLETE); + write_complete = true; + complete(&bfin_write_complete); } - if (rtc_istat & RTC_ISTAT_STOPWATCH) { - bfin_write_RTC_ISTAT(RTC_ISTAT_STOPWATCH); - events |= RTC_PF | RTC_IRQF; - bfin_write_RTC_SWCNT(rtc->rtc_dev->irq_freq); + if (rtc_ictl & (RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY)) { + if (rtc_istat & (RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY)) { + bfin_write_RTC_ISTAT(RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY); + events |= RTC_AF | RTC_IRQF; + } } - if (rtc_istat & RTC_ISTAT_SEC) { - bfin_write_RTC_ISTAT(RTC_ISTAT_SEC); - events |= RTC_UF | RTC_IRQF; + if (rtc_ictl & RTC_ISTAT_STOPWATCH) { + if (rtc_istat & RTC_ISTAT_STOPWATCH) { + bfin_write_RTC_ISTAT(RTC_ISTAT_STOPWATCH); + events |= RTC_PF | RTC_IRQF; + bfin_write_RTC_SWCNT(rtc->rtc_dev->irq_freq); + } } - rtc_update_irq(rtc->rtc_dev, 1, events); + if (rtc_ictl & RTC_ISTAT_SEC) { + if (rtc_istat & RTC_ISTAT_SEC) { + bfin_write_RTC_ISTAT(RTC_ISTAT_SEC); + events |= RTC_UF | RTC_IRQF; + } + } - spin_unlock_irq(&rtc->lock); + if (events) + rtc_update_irq(rtc->rtc_dev, 1, events); - return IRQ_HANDLED; + if (write_complete || events) + return IRQ_HANDLED; + else + return IRQ_NONE; } static int bfin_rtc_open(struct device *dev) @@ -183,13 +224,9 @@ static int bfin_rtc_open(struct device *dev) dev_dbg_stamp(dev); - ret = request_irq(IRQ_RTC, bfin_rtc_interrupt, IRQF_DISABLED, "rtc-bfin", dev); - if (unlikely(ret)) { - dev_err(dev, "request RTC IRQ failed with %d\n", ret); - return ret; - } - - rtc_bfin_reset(dev); + ret = request_irq(IRQ_RTC, bfin_rtc_interrupt, IRQF_SHARED, to_platform_device(dev)->name, dev); + if (!ret) + bfin_rtc_reset(dev); return ret; } @@ -197,93 +234,70 @@ static int bfin_rtc_open(struct device *dev) static void bfin_rtc_release(struct device *dev) { dev_dbg_stamp(dev); - rtc_bfin_reset(dev); + bfin_rtc_reset(dev); free_irq(IRQ_RTC, dev); } +static void bfin_rtc_int_set(struct bfin_rtc *rtc, u16 rtc_int) +{ + bfin_write_RTC_ISTAT(rtc_int); + bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() | rtc_int); +} +static void bfin_rtc_int_clear(struct bfin_rtc *rtc, u16 rtc_int) +{ + bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() & rtc_int); +} +static void bfin_rtc_int_set_alarm(struct bfin_rtc *rtc) +{ + /* Blackfin has different bits for whether the alarm is + * more than 24 hours away. + */ + bfin_rtc_int_set(rtc, (rtc->rtc_alarm.tm_yday == -1 ? RTC_ISTAT_ALARM : RTC_ISTAT_ALARM_DAY)); +} static int bfin_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg) { struct bfin_rtc *rtc = dev_get_drvdata(dev); + int ret = 0; dev_dbg_stamp(dev); + bfin_rtc_sync_pending(dev); + switch (cmd) { case RTC_PIE_ON: dev_dbg_stamp(dev); - spin_lock_irq(&rtc->lock); - rtc_bfin_sync_pending(); - bfin_write_RTC_ISTAT(RTC_ISTAT_STOPWATCH); + bfin_rtc_int_set(rtc, RTC_ISTAT_STOPWATCH); bfin_write_RTC_SWCNT(rtc->rtc_dev->irq_freq); - bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() | RTC_ISTAT_STOPWATCH); - spin_unlock_irq(&rtc->lock); - return 0; + break; case RTC_PIE_OFF: dev_dbg_stamp(dev); - spin_lock_irq(&rtc->lock); - rtc_bfin_sync_pending(); - bfin_write_RTC_SWCNT(0); - bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() & ~RTC_ISTAT_STOPWATCH); - spin_unlock_irq(&rtc->lock); - return 0; + bfin_rtc_int_clear(rtc, ~RTC_ISTAT_STOPWATCH); + break; case RTC_UIE_ON: dev_dbg_stamp(dev); - spin_lock_irq(&rtc->lock); - rtc_bfin_sync_pending(); - bfin_write_RTC_ISTAT(RTC_ISTAT_SEC); - bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() | RTC_ISTAT_SEC); - spin_unlock_irq(&rtc->lock); - return 0; + bfin_rtc_int_set(rtc, RTC_ISTAT_SEC); + break; case RTC_UIE_OFF: dev_dbg_stamp(dev); - spin_lock_irq(&rtc->lock); - rtc_bfin_sync_pending(); - bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() & ~RTC_ISTAT_SEC); - spin_unlock_irq(&rtc->lock); - return 0; - - case RTC_AIE_ON: { - unsigned long rtc_alarm; - u16 which_alarm; - int ret = 0; + bfin_rtc_int_clear(rtc, ~RTC_ISTAT_SEC); + break; + case RTC_AIE_ON: dev_dbg_stamp(dev); - - spin_lock_irq(&rtc->lock); - - rtc_bfin_sync_pending(); - if (rtc->rtc_alarm.tm_yday == -1) { - struct rtc_time now; - rtc_bfin_to_tm(bfin_read_RTC_STAT(), &now); - now.tm_sec = rtc->rtc_alarm.tm_sec; - now.tm_min = rtc->rtc_alarm.tm_min; - now.tm_hour = rtc->rtc_alarm.tm_hour; - ret = rtc_tm_to_time(&now, &rtc_alarm); - which_alarm = RTC_ISTAT_ALARM; - } else { - ret = rtc_tm_to_time(&rtc->rtc_alarm, &rtc_alarm); - which_alarm = RTC_ISTAT_ALARM_DAY; - } - if (ret == 0) { - bfin_write_RTC_ISTAT(which_alarm); - bfin_write_RTC_ALARM(rtc_time_to_bfin(rtc_alarm)); - bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() | which_alarm); - } - - spin_unlock_irq(&rtc->lock); - - return ret; - } + bfin_rtc_int_set_alarm(rtc); + break; case RTC_AIE_OFF: dev_dbg_stamp(dev); - spin_lock_irq(&rtc->lock); - rtc_bfin_sync_pending(); - bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() & ~(RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY)); - spin_unlock_irq(&rtc->lock); - return 0; + bfin_rtc_int_clear(rtc, ~(RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY)); + break; + + default: + dev_dbg_stamp(dev); + ret = -ENOIOCTLCMD; } - return -ENOIOCTLCMD; + return ret; } static int bfin_rtc_read_time(struct device *dev, struct rtc_time *tm) @@ -292,10 +306,10 @@ static int bfin_rtc_read_time(struct device *dev, struct rtc_time *tm) dev_dbg_stamp(dev); - spin_lock_irq(&rtc->lock); - rtc_bfin_sync_pending(); + if (rtc->rtc_wrote_regs & 0x1) + bfin_rtc_sync_pending(dev); + rtc_bfin_to_tm(bfin_read_RTC_STAT(), tm); - spin_unlock_irq(&rtc->lock); return 0; } @@ -308,16 +322,14 @@ static int bfin_rtc_set_time(struct device *dev, struct rtc_time *tm) dev_dbg_stamp(dev); - spin_lock_irq(&rtc->lock); - ret = rtc_tm_to_time(tm, &now); if (ret == 0) { - rtc_bfin_sync_pending(); + if (rtc->rtc_wrote_regs & 0x1) + bfin_rtc_sync_pending(dev); bfin_write_RTC_STAT(rtc_time_to_bfin(now)); + rtc->rtc_wrote_regs = 0x1; } - spin_unlock_irq(&rtc->lock); - return ret; } @@ -326,6 +338,7 @@ static int bfin_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm) struct bfin_rtc *rtc = dev_get_drvdata(dev); dev_dbg_stamp(dev); alrm->time = rtc->rtc_alarm; + bfin_rtc_sync_pending(dev); alrm->enabled = !!(bfin_read_RTC_ICTL() & (RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY)); return 0; } @@ -333,8 +346,20 @@ static int bfin_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm) static int bfin_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm) { struct bfin_rtc *rtc = dev_get_drvdata(dev); + unsigned long rtc_alarm; + dev_dbg_stamp(dev); + + if (rtc_tm_to_time(&alrm->time, &rtc_alarm)) + return -EINVAL; + rtc->rtc_alarm = alrm->time; + + bfin_rtc_sync_pending(dev); + bfin_write_RTC_ALARM(rtc_time_to_bfin(rtc_alarm)); + if (alrm->enabled) + bfin_rtc_int_set_alarm(rtc); + return 0; } @@ -393,8 +418,6 @@ static int __devinit bfin_rtc_probe(struct platform_device *pdev) if (unlikely(!rtc)) return -ENOMEM; - spin_lock_init(&rtc->lock); - rtc->rtc_dev = rtc_device_register(pdev->name, &pdev->dev, &bfin_rtc_ops, THIS_MODULE); if (unlikely(IS_ERR(rtc))) { ret = PTR_ERR(rtc->rtc_dev); -- cgit v1.2.3-18-g5258