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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 <michael.frysinger@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>
Acked-by: Alessandro Zummo <alessandro.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mike Frysinger 2008-02-06 01:38:51 -08:00 committed by Linus Torvalds
parent 48c1a56b4b
commit 095b9d546f
1 changed files with 138 additions and 115 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

253
drivers/rtc/rtc-bfin.c
View File

@ -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 <linux/module.h>
#include <linux/kernel.h>
#include <linux/bcd.h>
#include <linux/rtc.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/seq_file.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/seq_file.h>
#include <asm/blackfin.h>
@ -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);