/*
* "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 <linux/slab.h>
#include <mach/board.h>
#include <mach/at91_rtt.h>
#include <mach/cpu.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;
}
static int at91_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct sam9_rtc *rtc = dev_get_drvdata(dev);
u32 mr = rtt_readl(rtc, MR);
dev_dbg(dev, "alarm_irq_enable: enabled=%08x, mr %08x\n", enabled, mr);
if (enabled)
rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN);
else
rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);
return 0;
}
/*
* 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 >> 16);
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", __func__,
events >> 8, events & 0x000000FF);
return IRQ_HANDLED;
}
static const struct rtc_class_ops at91_rtc_ops = {
.read_time = at91_rtc_readtime,
.set_time = at91_rtc_settime,
.read_alarm = at91_rtc_readalarm,
.set_alarm = at91_rtc_setalarm,
.proc = at91_rtc_proc,
.alarm_irq_enable = at91_rtc_alarm_irq_enable,
};
/*
* 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 setup code should have handled this; sigh */
if (!device_can_wakeup(&pdev->dev))
device_init_wakeup(&pdev->dev, 1);
platform_set_drvdata(pdev, rtc);
rtc->rtt = ioremap(r->start, resource_size(r));
if (!rtc->rtt) {
dev_err(&pdev->dev, "failed to map registers, aborting.\n");
ret = -ENOMEM;
goto fail;
}
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;
}
/* register irq handler after we know what name we'll use */
ret = request_irq(AT91_ID_SYS, at91_rtc_interrupt,
IRQF_DISABLED | IRQF_SHARED,
dev_name(&rtc->rtcdev->dev), 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",
dev_name(&rtc->rtcdev->dev));
return 0;
fail_register:
iounmap(rtc->rtt);
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);
iounmap(rtc->rtt);
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");
