/* * "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 <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; } /* * 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 >> 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 = { .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 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 = (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, 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: 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");