diff options
| -rw-r--r-- | drivers/rtc/Kconfig | 10 | ||||
| -rw-r--r-- | drivers/rtc/Makefile | 1 | ||||
| -rw-r--r-- | drivers/rtc/rtc-bfin.c | 445 |
3 files changed, 456 insertions, 0 deletions
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig index 95826b92ca4..ef1eae98ba4 100644 --- a/drivers/rtc/Kconfig +++ b/drivers/rtc/Kconfig @@ -354,4 +354,14 @@ config RTC_DRV_V3020 This driver can also be built as a module. If so, the module will be called rtc-v3020. +config RTC_DRV_BFIN + tristate "Blackfin On-Chip RTC" + depends on RTC_CLASS && BFIN + help + If you say yes here you will get support for the + Blackfin On-Chip Real Time Clock. + + This driver can also be built as a module. If so, the module + will be called rtc-bfin. + endmenu diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile index 92bfe1b3a5f..9218cf28d6e 100644 --- a/drivers/rtc/Makefile +++ b/drivers/rtc/Makefile @@ -38,3 +38,4 @@ obj-$(CONFIG_RTC_DRV_MAX6902) += rtc-max6902.o obj-$(CONFIG_RTC_DRV_V3020) += rtc-v3020.o obj-$(CONFIG_RTC_DRV_AT91RM9200)+= rtc-at91rm9200.o obj-$(CONFIG_RTC_DRV_SH) += rtc-sh.o +obj-$(CONFIG_RTC_DRV_BFIN) += rtc-bfin.o diff --git a/drivers/rtc/rtc-bfin.c b/drivers/rtc/rtc-bfin.c new file mode 100644 index 00000000000..260ead95991 --- /dev/null +++ b/drivers/rtc/rtc-bfin.c @@ -0,0 +1,445 @@ +/* + * Blackfin On-Chip Real Time Clock Driver + * Supports BF531/BF532/BF533/BF534/BF536/BF537 + * + * Copyright 2004-2007 Analog Devices Inc. + * + * Enter bugs at http://blackfin.uclinux.org/ + * + * Licensed under the GPL-2 or later. + */ + +/* The biggest issue we deal with in this driver is that register writes are + * synced to the RTC frequency of 1Hz. So if you write to a register and + * attempt to write again before the first write has completed, the new write + * is simply discarded. This can easily be troublesome if userspace disables + * one event (say periodic) and then right after enables an event (say alarm). + * Since all events are maintained in the same interrupt mask register, if + * we wrote to it to disable the first event and then wrote to it again to + * enable the second event, that second event would not be enabled as the + * write would be discarded and things quickly fall apart. + * + * To keep this delay from significantly degrading performance (we, in theory, + * would have to sleep for up to 1 second everytime we wanted to write a + * register), we only check the write pending status before we start to issue + * a new write. We bank on the idea that it doesnt matter when the sync + * happens so long as we don't attempt another write before it does. The only + * time userspace would take this penalty is when they try and do multiple + * operations right after another ... but in this case, they need to take the + * sync penalty, so we should be OK. + * + * Also note that the RTC_ISTAT register does not suffer this penalty; its + * 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/delay.h> + +#include <asm/blackfin.h> + +#define stamp(fmt, args...) pr_debug("%s:%i: " fmt "\n", __FUNCTION__, __LINE__, ## args) +#define stampit() stamp("here i am") + +struct bfin_rtc { + struct rtc_device *rtc_dev; + struct rtc_time rtc_alarm; + spinlock_t lock; +}; + +/* Bit values for the ISTAT / ICTL registers */ +#define RTC_ISTAT_WRITE_COMPLETE 0x8000 +#define RTC_ISTAT_WRITE_PENDING 0x4000 +#define RTC_ISTAT_ALARM_DAY 0x0040 +#define RTC_ISTAT_24HR 0x0020 +#define RTC_ISTAT_HOUR 0x0010 +#define RTC_ISTAT_MIN 0x0008 +#define RTC_ISTAT_SEC 0x0004 +#define RTC_ISTAT_ALARM 0x0002 +#define RTC_ISTAT_STOPWATCH 0x0001 + +/* Shift values for RTC_STAT register */ +#define DAY_BITS_OFF 17 +#define HOUR_BITS_OFF 12 +#define MIN_BITS_OFF 6 +#define SEC_BITS_OFF 0 + +/* Some helper functions to convert between the common RTC notion of time + * and the internal Blackfin notion that is stored in 32bits. + */ +static inline u32 rtc_time_to_bfin(unsigned long now) +{ + u32 sec = (now % 60); + u32 min = (now % (60 * 60)) / 60; + u32 hour = (now % (60 * 60 * 24)) / (60 * 60); + u32 days = (now / (60 * 60 * 24)); + return (sec << SEC_BITS_OFF) + + (min << MIN_BITS_OFF) + + (hour << HOUR_BITS_OFF) + + (days << DAY_BITS_OFF); +} +static inline unsigned long rtc_bfin_to_time(u32 rtc_bfin) +{ + return (((rtc_bfin >> SEC_BITS_OFF) & 0x003F)) + + (((rtc_bfin >> MIN_BITS_OFF) & 0x003F) * 60) + + (((rtc_bfin >> HOUR_BITS_OFF) & 0x001F) * 60 * 60) + + (((rtc_bfin >> DAY_BITS_OFF) & 0x7FFF) * 60 * 60 * 24); +} +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. + * Unfortunately, we can't sleep here as that introduces a race condition when + * turning on interrupt events. Consider this: + * - process sets alarm + * - process enables alarm + * - process sleeps while waiting for rtc write to sync + * - interrupt fires while process is sleeping + * - interrupt acks the event by writing to ISTAT + * - interrupt sets the WRITE PENDING bit + * - interrupt handler finishes + * - process wakes up, sees WRITE PENDING bit set, goes to sleep + * - interrupt fires while process is sleeping + * If anyone can point out the obvious solution here, i'm listening :). This + * shouldn't be an issue on an SMP or preempt system as this function should + * only be called with the rtc lock held. + */ +static void rtc_bfin_sync_pending(void) +{ + stampit(); + 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 void rtc_bfin_reset(struct bfin_rtc *rtc) +{ + /* 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(); + bfin_write_RTC_PREN(0x1); + bfin_write_RTC_ICTL(0); + bfin_write_RTC_SWCNT(0); + bfin_write_RTC_ALARM(0); + bfin_write_RTC_ISTAT(0xFFFF); + spin_unlock_irq(&rtc->lock); +} + +static irqreturn_t bfin_rtc_interrupt(int irq, void *dev_id) +{ + struct platform_device *pdev = to_platform_device(dev_id); + struct bfin_rtc *rtc = platform_get_drvdata(pdev); + unsigned long events = 0; + u16 rtc_istat; + + stampit(); + + spin_lock_irq(&rtc->lock); + + rtc_istat = bfin_read_RTC_ISTAT(); + + 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_STOPWATCH) { + bfin_write_RTC_ISTAT(RTC_ISTAT_STOPWATCH); + events |= RTC_PF | RTC_IRQF; + bfin_write_RTC_SWCNT(rtc->rtc_dev->irq_freq); + } + + if (rtc_istat & RTC_ISTAT_SEC) { + bfin_write_RTC_ISTAT(RTC_ISTAT_SEC); + events |= RTC_UF | RTC_IRQF; + } + + rtc_update_irq(rtc->rtc_dev, 1, events); + + spin_unlock_irq(&rtc->lock); + + return IRQ_HANDLED; +} + +static int bfin_rtc_open(struct device *dev) +{ + struct bfin_rtc *rtc = dev_get_drvdata(dev); + int ret; + + stampit(); + + 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(rtc); + + return ret; +} + +static void bfin_rtc_release(struct device *dev) +{ + struct bfin_rtc *rtc = dev_get_drvdata(dev); + stampit(); + rtc_bfin_reset(rtc); + free_irq(IRQ_RTC, dev); +} + +static int bfin_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg) +{ + struct bfin_rtc *rtc = dev_get_drvdata(dev); + + stampit(); + + switch (cmd) { + case RTC_PIE_ON: + stampit(); + spin_lock_irq(&rtc->lock); + rtc_bfin_sync_pending(); + bfin_write_RTC_ISTAT(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; + case RTC_PIE_OFF: + stampit(); + 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; + + case RTC_UIE_ON: + stampit(); + 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; + case RTC_UIE_OFF: + stampit(); + 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; + + stampit(); + + 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; + } + case RTC_AIE_OFF: + stampit(); + 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; + } + + return -ENOIOCTLCMD; +} + +static int bfin_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct bfin_rtc *rtc = dev_get_drvdata(dev); + + stampit(); + + spin_lock_irq(&rtc->lock); + rtc_bfin_sync_pending(); + rtc_bfin_to_tm(bfin_read_RTC_STAT(), tm); + spin_unlock_irq(&rtc->lock); + + return 0; +} + +static int bfin_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct bfin_rtc *rtc = dev_get_drvdata(dev); + int ret; + unsigned long now; + + stampit(); + + spin_lock_irq(&rtc->lock); + + ret = rtc_tm_to_time(tm, &now); + if (ret == 0) { + rtc_bfin_sync_pending(); + bfin_write_RTC_STAT(rtc_time_to_bfin(now)); + } + + spin_unlock_irq(&rtc->lock); + + return ret; +} + +static int bfin_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm) +{ + struct bfin_rtc *rtc = dev_get_drvdata(dev); + stampit(); + memcpy(&alrm->time, &rtc->rtc_alarm, sizeof(struct rtc_time)); + alrm->pending = !!(bfin_read_RTC_ICTL() & (RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY)); + return 0; +} + +static int bfin_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm) +{ + struct bfin_rtc *rtc = dev_get_drvdata(dev); + stampit(); + memcpy(&rtc->rtc_alarm, &alrm->time, sizeof(struct rtc_time)); + return 0; +} + +static int bfin_rtc_proc(struct device *dev, struct seq_file *seq) +{ +#define yesno(x) (x ? "yes" : "no") + u16 ictl = bfin_read_RTC_ICTL(); + stampit(); + seq_printf(seq, "alarm_IRQ\t: %s\n", yesno(ictl & RTC_ISTAT_ALARM)); + seq_printf(seq, "wkalarm_IRQ\t: %s\n", yesno(ictl & RTC_ISTAT_ALARM_DAY)); + seq_printf(seq, "seconds_IRQ\t: %s\n", yesno(ictl & RTC_ISTAT_SEC)); + seq_printf(seq, "periodic_IRQ\t: %s\n", yesno(ictl & RTC_ISTAT_STOPWATCH)); +#ifdef DEBUG + seq_printf(seq, "RTC_STAT\t: 0x%08X\n", bfin_read_RTC_STAT()); + seq_printf(seq, "RTC_ICTL\t: 0x%04X\n", bfin_read_RTC_ICTL()); + seq_printf(seq, "RTC_ISTAT\t: 0x%04X\n", bfin_read_RTC_ISTAT()); + seq_printf(seq, "RTC_SWCNT\t: 0x%04X\n", bfin_read_RTC_SWCNT()); + seq_printf(seq, "RTC_ALARM\t: 0x%08X\n", bfin_read_RTC_ALARM()); + seq_printf(seq, "RTC_PREN\t: 0x%04X\n", bfin_read_RTC_PREN()); +#endif + return 0; +} + +static int bfin_irq_set_freq(struct device *dev, int freq) +{ + struct bfin_rtc *rtc = dev_get_drvdata(dev); + stampit(); + rtc->rtc_dev->irq_freq = freq; + return 0; +} + +static struct rtc_class_ops bfin_rtc_ops = { + .open = bfin_rtc_open, + .release = bfin_rtc_release, + .ioctl = bfin_rtc_ioctl, + .read_time = bfin_rtc_read_time, + .set_time = bfin_rtc_set_time, + .read_alarm = bfin_rtc_read_alarm, + .set_alarm = bfin_rtc_set_alarm, + .proc = bfin_rtc_proc, + .irq_set_freq = bfin_irq_set_freq, +}; + +static int __devinit bfin_rtc_probe(struct platform_device *pdev) +{ + struct bfin_rtc *rtc; + int ret = 0; + + stampit(); + + rtc = kzalloc(sizeof(*rtc), GFP_KERNEL); + 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); + goto err; + } + rtc->rtc_dev->irq_freq = 0; + rtc->rtc_dev->max_user_freq = (2 << 16); /* stopwatch is an unsigned 16 bit reg */ + + platform_set_drvdata(pdev, rtc); + + return 0; + +err: + kfree(rtc); + return ret; +} + +static int __devexit bfin_rtc_remove(struct platform_device *pdev) +{ + struct bfin_rtc *rtc = platform_get_drvdata(pdev); + + rtc_device_unregister(rtc->rtc_dev); + platform_set_drvdata(pdev, NULL); + kfree(rtc); + + return 0; +} + +static struct platform_driver bfin_rtc_driver = { + .driver = { + .name = "rtc-bfin", + .owner = THIS_MODULE, + }, + .probe = bfin_rtc_probe, + .remove = __devexit_p(bfin_rtc_remove), +}; + +static int __init bfin_rtc_init(void) +{ + stampit(); + return platform_driver_register(&bfin_rtc_driver); +} + +static void __exit bfin_rtc_exit(void) +{ + platform_driver_unregister(&bfin_rtc_driver); +} + +module_init(bfin_rtc_init); +module_exit(bfin_rtc_exit); + +MODULE_DESCRIPTION("Blackfin On-Chip Real Time Clock Driver"); +MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>"); +MODULE_LICENSE("GPL"); |