diff options
Diffstat (limited to 'drivers/rtc/rtc-at91sam9.c')
| -rw-r--r-- | drivers/rtc/rtc-at91sam9.c | 520 |
1 files changed, 520 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-at91sam9.c b/drivers/rtc/rtc-at91sam9.c new file mode 100644 index 00000000000..bbf10ecf416 --- /dev/null +++ b/drivers/rtc/rtc-at91sam9.c @@ -0,0 +1,520 @@ +/* + * "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"); |