--- /dev/null
+/*
+ * "RTT as Real Time Clock" driver for AT91SAM9 SoC family
+ *
+ * (C) 2007 Michel Benoit
+ *
+ * Based on rtc-at91rm9200.c by Rick Bronson
+ *
+ * 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.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/time.h>
+#include <linux/rtc.h>
+#include <linux/interrupt.h>
+#include <linux/ioctl.h>
+
+#include <asm/mach/time.h>
+#include <asm/arch/board.h>
+#include <asm/arch/at91_rtt.h>
+
+
+/*
+ * 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.
+ */
+
+/*
+ * 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)
+
+
+struct sam9_rtc {
+ void __iomem *rtt;
+ struct rtc_device *rtcdev;
+ u32 imr;
+};
+
+#define rtt_readl(rtc, field) \
+ __raw_readl((rtc)->rtt + AT91_RTT_ ## field)
+#define rtt_writel(rtc, field, val) \
+ __raw_writel((val), (rtc)->rtt + AT91_RTT_ ## field)
+
+#define gpbr_readl(rtc) \
+ at91_sys_read(AT91_GPBR + 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR)
+#define gpbr_writel(rtc, val) \
+ at91_sys_write(AT91_GPBR + 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR, (val))
+
+/*
+ * Read current time and date in RTC
+ */
+static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm)
+{
+ struct sam9_rtc *rtc = dev_get_drvdata(dev);
+ u32 secs, secs2;
+ u32 offset;
+
+ /* read current time offset */
+ offset = gpbr_readl(rtc);
+ if (offset == 0)
+ return -EILSEQ;
+
+ /* reread the counter to help sync the two clock domains */
+ secs = rtt_readl(rtc, VR);
+ secs2 = rtt_readl(rtc, VR);
+ if (secs != secs2)
+ secs = rtt_readl(rtc, VR);
+
+ rtc_time_to_tm(offset + secs, tm);
+
+ dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readtime",
+ 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
+ tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+ return 0;
+}
+
+/*
+ * Set current time and date in RTC
+ */
+static int at91_rtc_settime(struct device *dev, struct rtc_time *tm)
+{
+ struct sam9_rtc *rtc = dev_get_drvdata(dev);
+ int err;
+ u32 offset, alarm, mr;
+ unsigned long secs;
+
+ dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "settime",
+ 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
+ tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+ err = rtc_tm_to_time(tm, &secs);
+ if (err != 0)
+ return err;
+
+ mr = rtt_readl(rtc, MR);
+
+ /* disable interrupts */
+ rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN));
+
+ /* read current time offset */
+ offset = gpbr_readl(rtc);
+
+ /* store the new base time in a battery backup register */
+ secs += 1;
+ gpbr_writel(rtc, secs);
+
+ /* adjust the alarm time for the new base */
+ alarm = rtt_readl(rtc, AR);
+ if (alarm != ALARM_DISABLED) {
+ if (offset > secs) {
+ /* time jumped backwards, increase time until alarm */
+ alarm += (offset - secs);
+ } else if ((alarm + offset) > secs) {
+ /* time jumped forwards, decrease time until alarm */
+ alarm -= (secs - offset);
+ } else {
+ /* time jumped past the alarm, disable alarm */
+ alarm = ALARM_DISABLED;
+ mr &= ~AT91_RTT_ALMIEN;
+ }
+ rtt_writel(rtc, AR, alarm);
+ }
+
+ /* reset the timer, and re-enable interrupts */
+ rtt_writel(rtc, MR, mr | AT91_RTT_RTTRST);
+
+ return 0;
+}
+
+static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+ struct sam9_rtc *rtc = dev_get_drvdata(dev);
+ struct rtc_time *tm = &alrm->time;
+ u32 alarm = rtt_readl(rtc, AR);
+ u32 offset;
+
+ offset = gpbr_readl(rtc);
+ if (offset == 0)
+ return -EILSEQ;
+
+ memset(alrm, 0, sizeof(alrm));
+ if (alarm != ALARM_DISABLED && offset != 0) {
+ rtc_time_to_tm(offset + alarm, tm);
+
+ dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readalarm",
+ 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
+ tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+ if (rtt_readl(rtc, MR) & AT91_RTT_ALMIEN)
+ alrm->enabled = 1;
+ }
+
+ return 0;
+}
+
+static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+ struct sam9_rtc *rtc = dev_get_drvdata(dev);
+ struct rtc_time *tm = &alrm->time;
+ unsigned long secs;
+ u32 offset;
+ u32 mr;
+ int err;
+
+ err = rtc_tm_to_time(tm, &secs);
+ if (err != 0)
+ return err;
+
+ offset = gpbr_readl(rtc);
+ if (offset == 0) {
+ /* time is not set */
+ return -EILSEQ;
+ }
+ mr = rtt_readl(rtc, MR);
+ rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);
+
+ /* alarm in the past? finish and leave disabled */
+ if (secs <= offset) {
+ rtt_writel(rtc, AR, ALARM_DISABLED);
+ return 0;
+ }
+
+ /* else set alarm and maybe enable it */
+ rtt_writel(rtc, AR, secs - offset);
+ if (alrm->enabled)
+ rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN);
+
+ dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "setalarm",
+ tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour,
+ tm->tm_min, tm->tm_sec);
+
+ return 0;
+}
+
+/*
+ * Handle commands from user-space
+ */
+static int at91_rtc_ioctl(struct device *dev, unsigned int cmd,
+ unsigned long arg)
+{
+ struct sam9_rtc *rtc = dev_get_drvdata(dev);
+ int ret = 0;
+ u32 mr = rtt_readl(rtc, MR);
+
+ dev_dbg(dev, "ioctl: cmd=%08x, arg=%08lx, mr %08x\n", cmd, arg, mr);
+
+ switch (cmd) {
+ case RTC_AIE_OFF: /* alarm off */
+ rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);
+ break;
+ case RTC_AIE_ON: /* alarm on */
+ rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN);
+ break;
+ case RTC_UIE_OFF: /* update off */
+ rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN);
+ break;
+ case RTC_UIE_ON: /* update on */
+ rtt_writel(rtc, MR, mr | AT91_RTT_RTTINCIEN);
+ break;
+ default:
+ ret = -ENOIOCTLCMD;
+ break;
+ }
+
+ return ret;
+}
+
+/*
+ * Provide additional RTC information in /proc/driver/rtc
+ */
+static int at91_rtc_proc(struct device *dev, struct seq_file *seq)
+{
+ struct sam9_rtc *rtc = dev_get_drvdata(dev);
+ u32 mr = mr = rtt_readl(rtc, MR);
+
+ seq_printf(seq, "update_IRQ\t: %s\n",
+ (mr & AT91_RTT_RTTINCIEN) ? "yes" : "no");
+ return 0;
+}
+
+/*
+ * IRQ handler for the RTC
+ */
+static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc)
+{
+ struct sam9_rtc *rtc = _rtc;
+ u32 sr, mr;
+ unsigned long events = 0;
+
+ /* Shared interrupt may be for another device. Note: reading
+ * SR clears it, so we must only read it in this irq handler!
+ */
+ mr = rtt_readl(rtc, MR) & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
+ sr = rtt_readl(rtc, SR) & mr;
+ if (!sr)
+ return IRQ_NONE;
+
+ /* alarm status */
+ if (sr & AT91_RTT_ALMS)
+ events |= (RTC_AF | RTC_IRQF);
+
+ /* timer update/increment */
+ if (sr & AT91_RTT_RTTINC)
+ events |= (RTC_UF | RTC_IRQF);
+
+ rtc_update_irq(rtc->rtcdev, 1, events);
+
+ pr_debug("%s: num=%ld, events=0x%02lx\n", __FUNCTION__,
+ events >> 8, events & 0x000000FF);
+
+ return IRQ_HANDLED;
+}
+
+static const struct rtc_class_ops at91_rtc_ops = {
+ .ioctl = at91_rtc_ioctl,
+ .read_time = at91_rtc_readtime,
+ .set_time = at91_rtc_settime,
+ .read_alarm = at91_rtc_readalarm,
+ .set_alarm = at91_rtc_setalarm,
+ .proc = at91_rtc_proc,
+};
+
+/*
+ * Initialize and install RTC driver
+ */
+static int __init at91_rtc_probe(struct platform_device *pdev)
+{
+ struct resource *r;
+ struct sam9_rtc *rtc;
+ int ret;
+ u32 mr;
+
+ r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!r)
+ return -ENODEV;
+
+ rtc = kzalloc(sizeof *rtc, GFP_KERNEL);
+ if (!rtc)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, rtc);
+ rtc->rtt = (void __force __iomem *) (AT91_VA_BASE_SYS - AT91_BASE_SYS);
+ rtc->rtt += r->start;
+
+ mr = rtt_readl(rtc, MR);
+
+ /* unless RTT is counting at 1 Hz, re-initialize it */
+ if ((mr & AT91_RTT_RTPRES) != AT91_SLOW_CLOCK) {
+ mr = AT91_RTT_RTTRST | (AT91_SLOW_CLOCK & AT91_RTT_RTPRES);
+ gpbr_writel(rtc, 0);
+ }
+
+ /* disable all interrupts (same as on shutdown path) */
+ mr &= ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
+ rtt_writel(rtc, MR, mr);
+
+ rtc->rtcdev = rtc_device_register(pdev->name, &pdev->dev,
+ &at91_rtc_ops, THIS_MODULE);
+ if (IS_ERR(rtc->rtcdev)) {
+ ret = PTR_ERR(rtc->rtcdev);
+ goto fail;
+ }
+
+ /* register irq handler after we know what name we'll use */
+ ret = request_irq(AT91_ID_SYS, at91_rtc_interrupt,
+ IRQF_DISABLED | IRQF_SHARED,
+ rtc->rtcdev->dev.bus_id, rtc);
+ if (ret) {
+ dev_dbg(&pdev->dev, "can't share IRQ %d?\n", AT91_ID_SYS);
+ rtc_device_unregister(rtc->rtcdev);
+ goto fail;
+ }
+
+ /* NOTE: sam9260 rev A silicon has a ROM bug which resets the
+ * 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");
projects / linux-2.6-microblaze.git / commitdiff