rtc: hctosys: Ensure system time doesn't overflow time_t

[mirror_ubuntu-bionic-kernel.git] / drivers / rtc / rtc-at91rm9200.c

/*
 *      Real Time Clock interface for Linux on Atmel AT91RM9200
 *
 *      Copyright (C) 2002 Rick Bronson
 *
 *      Converted to RTC class model by Andrew Victor
 *
 *      Ported to Linux 2.6 by Steven Scholz
 *      Based on s3c2410-rtc.c Simtec Electronics
 *
 *      Based on sa1100-rtc.c by Nils Faerber
 *      Based on rtc.c by Paul Gortmaker
 *
 *      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/bcd.h>
#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/interrupt.h>
#include <linux/ioctl.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/spinlock.h>
#include <linux/suspend.h>
#include <linux/time.h>
#include <linux/uaccess.h>

#include "rtc-at91rm9200.h"

#define at91_rtc_read(field) \
        readl_relaxed(at91_rtc_regs + field)
#define at91_rtc_write(field, val) \
        writel_relaxed((val), at91_rtc_regs + field)

struct at91_rtc_config {
        bool use_shadow_imr;
};

static const struct at91_rtc_config *at91_rtc_config;
static DECLARE_COMPLETION(at91_rtc_updated);
static DECLARE_COMPLETION(at91_rtc_upd_rdy);
static void __iomem *at91_rtc_regs;
static int irq;
static DEFINE_SPINLOCK(at91_rtc_lock);
static u32 at91_rtc_shadow_imr;
static bool suspended;
static DEFINE_SPINLOCK(suspended_lock);
static unsigned long cached_events;
static u32 at91_rtc_imr;
static struct clk *sclk;

static void at91_rtc_write_ier(u32 mask)
{
        unsigned long flags;

        spin_lock_irqsave(&at91_rtc_lock, flags);
        at91_rtc_shadow_imr |= mask;
        at91_rtc_write(AT91_RTC_IER, mask);
        spin_unlock_irqrestore(&at91_rtc_lock, flags);
}

static void at91_rtc_write_idr(u32 mask)
{
        unsigned long flags;

        spin_lock_irqsave(&at91_rtc_lock, flags);
        at91_rtc_write(AT91_RTC_IDR, mask);
        /*
         * Register read back (of any RTC-register) needed to make sure
         * IDR-register write has reached the peripheral before updating
         * shadow mask.
         *
         * Note that there is still a possibility that the mask is updated
         * before interrupts have actually been disabled in hardware. The only
         * way to be certain would be to poll the IMR-register, which is is
         * the very register we are trying to emulate. The register read back
         * is a reasonable heuristic.
         */
        at91_rtc_read(AT91_RTC_SR);
        at91_rtc_shadow_imr &= ~mask;
        spin_unlock_irqrestore(&at91_rtc_lock, flags);
}

static u32 at91_rtc_read_imr(void)
{
        unsigned long flags;
        u32 mask;

        if (at91_rtc_config->use_shadow_imr) {
                spin_lock_irqsave(&at91_rtc_lock, flags);
                mask = at91_rtc_shadow_imr;
                spin_unlock_irqrestore(&at91_rtc_lock, flags);
        } else {
                mask = at91_rtc_read(AT91_RTC_IMR);
        }

        return mask;
}

/*
 * Decode time/date into rtc_time structure
 */
static void at91_rtc_decodetime(unsigned int timereg, unsigned int calreg,
                                struct rtc_time *tm)
{
        unsigned int time, date;

        /* must read twice in case it changes */
        do {
                time = at91_rtc_read(timereg);
                date = at91_rtc_read(calreg);
        } while ((time != at91_rtc_read(timereg)) ||
                        (date != at91_rtc_read(calreg)));

        tm->tm_sec  = bcd2bin((time & AT91_RTC_SEC) >> 0);
        tm->tm_min  = bcd2bin((time & AT91_RTC_MIN) >> 8);
        tm->tm_hour = bcd2bin((time & AT91_RTC_HOUR) >> 16);

        /*
         * The Calendar Alarm register does not have a field for
         * the year - so these will return an invalid value.
         */
        tm->tm_year  = bcd2bin(date & AT91_RTC_CENT) * 100;     /* century */
        tm->tm_year += bcd2bin((date & AT91_RTC_YEAR) >> 8);    /* year */

        tm->tm_wday = bcd2bin((date & AT91_RTC_DAY) >> 21) - 1; /* day of the week [0-6], Sunday=0 */
        tm->tm_mon  = bcd2bin((date & AT91_RTC_MONTH) >> 16) - 1;
        tm->tm_mday = bcd2bin((date & AT91_RTC_DATE) >> 24);
}

/*
 * Read current time and date in RTC
 */
static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm)
{
        at91_rtc_decodetime(AT91_RTC_TIMR, AT91_RTC_CALR, tm);
        tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
        tm->tm_year = tm->tm_year - 1900;

        dev_dbg(dev, "%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __func__,
                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)
{
        unsigned long cr;

        dev_dbg(dev, "%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __func__,
                1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
                tm->tm_hour, tm->tm_min, tm->tm_sec);

        wait_for_completion(&at91_rtc_upd_rdy);

        /* Stop Time/Calendar from counting */
        cr = at91_rtc_read(AT91_RTC_CR);
        at91_rtc_write(AT91_RTC_CR, cr | AT91_RTC_UPDCAL | AT91_RTC_UPDTIM);

        at91_rtc_write_ier(AT91_RTC_ACKUPD);
        wait_for_completion(&at91_rtc_updated); /* wait for ACKUPD interrupt */
        at91_rtc_write_idr(AT91_RTC_ACKUPD);

        at91_rtc_write(AT91_RTC_TIMR,
                          bin2bcd(tm->tm_sec) << 0
                        | bin2bcd(tm->tm_min) << 8
                        | bin2bcd(tm->tm_hour) << 16);

        at91_rtc_write(AT91_RTC_CALR,
                          bin2bcd((tm->tm_year + 1900) / 100)   /* century */
                        | bin2bcd(tm->tm_year % 100) << 8       /* year */
                        | bin2bcd(tm->tm_mon + 1) << 16         /* tm_mon starts at zero */
                        | bin2bcd(tm->tm_wday + 1) << 21        /* day of the week [0-6], Sunday=0 */
                        | bin2bcd(tm->tm_mday) << 24);

        /* Restart Time/Calendar */
        cr = at91_rtc_read(AT91_RTC_CR);
        at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_SECEV);
        at91_rtc_write(AT91_RTC_CR, cr & ~(AT91_RTC_UPDCAL | AT91_RTC_UPDTIM));
        at91_rtc_write_ier(AT91_RTC_SECEV);

        return 0;
}

/*
 * Read alarm time and date in RTC
 */
static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct rtc_time *tm = &alrm->time;

        at91_rtc_decodetime(AT91_RTC_TIMALR, AT91_RTC_CALALR, tm);
        tm->tm_year = -1;

        alrm->enabled = (at91_rtc_read_imr() & AT91_RTC_ALARM)
                        ? 1 : 0;

        dev_dbg(dev, "%s(): %02d-%02d %02d:%02d:%02d %sabled\n", __func__,
                tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec,
                alrm->enabled ? "en" : "dis");

        return 0;
}

/*
 * Set alarm time and date in RTC
 */
static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct rtc_time tm;

        at91_rtc_decodetime(AT91_RTC_TIMR, AT91_RTC_CALR, &tm);

        tm.tm_mon = alrm->time.tm_mon;
        tm.tm_mday = alrm->time.tm_mday;
        tm.tm_hour = alrm->time.tm_hour;
        tm.tm_min = alrm->time.tm_min;
        tm.tm_sec = alrm->time.tm_sec;

        at91_rtc_write_idr(AT91_RTC_ALARM);
        at91_rtc_write(AT91_RTC_TIMALR,
                  bin2bcd(tm.tm_sec) << 0
                | bin2bcd(tm.tm_min) << 8
                | bin2bcd(tm.tm_hour) << 16
                | AT91_RTC_HOUREN | AT91_RTC_MINEN | AT91_RTC_SECEN);
        at91_rtc_write(AT91_RTC_CALALR,
                  bin2bcd(tm.tm_mon + 1) << 16          /* tm_mon starts at zero */
                | bin2bcd(tm.tm_mday) << 24
                | AT91_RTC_DATEEN | AT91_RTC_MTHEN);

        if (alrm->enabled) {
                at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_ALARM);
                at91_rtc_write_ier(AT91_RTC_ALARM);
        }

        dev_dbg(dev, "%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __func__,
                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)
{
        dev_dbg(dev, "%s(): cmd=%08x\n", __func__, enabled);

        if (enabled) {
                at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_ALARM);
                at91_rtc_write_ier(AT91_RTC_ALARM);
        } else
                at91_rtc_write_idr(AT91_RTC_ALARM);

        return 0;
}
/*
 * Provide additional RTC information in /proc/driver/rtc
 */
static int at91_rtc_proc(struct device *dev, struct seq_file *seq)
{
        unsigned long imr = at91_rtc_read_imr();

        seq_printf(seq, "update_IRQ\t: %s\n",
                        (imr & AT91_RTC_ACKUPD) ? "yes" : "no");
        seq_printf(seq, "periodic_IRQ\t: %s\n",
                        (imr & AT91_RTC_SECEV) ? "yes" : "no");

        return 0;
}

/*
 * IRQ handler for the RTC
 */
static irqreturn_t at91_rtc_interrupt(int irq, void *dev_id)
{
        struct platform_device *pdev = dev_id;
        struct rtc_device *rtc = platform_get_drvdata(pdev);
        unsigned int rtsr;
        unsigned long events = 0;
        int ret = IRQ_NONE;

        spin_lock(&suspended_lock);
        rtsr = at91_rtc_read(AT91_RTC_SR) & at91_rtc_read_imr();
        if (rtsr) {             /* this interrupt is shared!  Is it ours? */
                if (rtsr & AT91_RTC_ALARM)
                        events |= (RTC_AF | RTC_IRQF);
                if (rtsr & AT91_RTC_SECEV) {
                        complete(&at91_rtc_upd_rdy);
                        at91_rtc_write_idr(AT91_RTC_SECEV);
                }
                if (rtsr & AT91_RTC_ACKUPD)
                        complete(&at91_rtc_updated);

                at91_rtc_write(AT91_RTC_SCCR, rtsr);    /* clear status reg */

                if (!suspended) {
                        rtc_update_irq(rtc, 1, events);

                        dev_dbg(&pdev->dev, "%s(): num=%ld, events=0x%02lx\n",
                                __func__, events >> 8, events & 0x000000FF);
                } else {
                        cached_events |= events;
                        at91_rtc_write_idr(at91_rtc_imr);
                        pm_system_wakeup();
                }

                ret = IRQ_HANDLED;
        }
        spin_unlock(&suspended_lock);

        return ret;
}

static const struct at91_rtc_config at91rm9200_config = {
};

static const struct at91_rtc_config at91sam9x5_config = {
        .use_shadow_imr = true,
};

#ifdef CONFIG_OF
static const struct of_device_id at91_rtc_dt_ids[] = {
        {
                .compatible = "atmel,at91rm9200-rtc",
                .data = &at91rm9200_config,
        }, {
                .compatible = "atmel,at91sam9x5-rtc",
                .data = &at91sam9x5_config,
        }, {
                /* sentinel */
        }
};
MODULE_DEVICE_TABLE(of, at91_rtc_dt_ids);
#endif

static const struct at91_rtc_config *
at91_rtc_get_config(struct platform_device *pdev)
{
        const struct of_device_id *match;

        if (pdev->dev.of_node) {
                match = of_match_node(at91_rtc_dt_ids, pdev->dev.of_node);
                if (!match)
                        return NULL;
                return (const struct at91_rtc_config *)match->data;
        }

        return &at91rm9200_config;
}

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 rtc_device *rtc;
        struct resource *regs;
        int ret = 0;

        at91_rtc_config = at91_rtc_get_config(pdev);
        if (!at91_rtc_config)
                return -ENODEV;

        regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!regs) {
                dev_err(&pdev->dev, "no mmio resource defined\n");
                return -ENXIO;
        }

        irq = platform_get_irq(pdev, 0);
        if (irq < 0) {
                dev_err(&pdev->dev, "no irq resource defined\n");
                return -ENXIO;
        }

        at91_rtc_regs = devm_ioremap(&pdev->dev, regs->start,
                                     resource_size(regs));
        if (!at91_rtc_regs) {
                dev_err(&pdev->dev, "failed to map registers, aborting.\n");
                return -ENOMEM;
        }

        rtc = devm_rtc_allocate_device(&pdev->dev);
        if (IS_ERR(rtc))
                return PTR_ERR(rtc);
        platform_set_drvdata(pdev, rtc);

        sclk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(sclk))
                return PTR_ERR(sclk);

        ret = clk_prepare_enable(sclk);
        if (ret) {
                dev_err(&pdev->dev, "Could not enable slow clock\n");
                return ret;
        }

        at91_rtc_write(AT91_RTC_CR, 0);
        at91_rtc_write(AT91_RTC_MR, 0);         /* 24 hour mode */

        /* Disable all interrupts */
        at91_rtc_write_idr(AT91_RTC_ACKUPD | AT91_RTC_ALARM |
                                        AT91_RTC_SECEV | AT91_RTC_TIMEV |
                                        AT91_RTC_CALEV);

        ret = devm_request_irq(&pdev->dev, irq, at91_rtc_interrupt,
                               IRQF_SHARED | IRQF_COND_SUSPEND,
                               "at91_rtc", pdev);
        if (ret) {
                dev_err(&pdev->dev, "IRQ %d already in use.\n", irq);
                goto err_clk;
        }

        /* cpu init code should really have flagged this device as
         * being wake-capable; if it didn't, do that here.
         */
        if (!device_can_wakeup(&pdev->dev))
                device_init_wakeup(&pdev->dev, 1);

        rtc->ops = &at91_rtc_ops;
        ret = rtc_register_device(rtc);
        if (ret)
                goto err_clk;

        /* enable SECEV interrupt in order to initialize at91_rtc_upd_rdy
         * completion.
         */
        at91_rtc_write_ier(AT91_RTC_SECEV);

        dev_info(&pdev->dev, "AT91 Real Time Clock driver.\n");
        return 0;

err_clk:
        clk_disable_unprepare(sclk);

        return ret;
}

/*
 * Disable and remove the RTC driver
 */
static int __exit at91_rtc_remove(struct platform_device *pdev)
{
        /* Disable all interrupts */
        at91_rtc_write_idr(AT91_RTC_ACKUPD | AT91_RTC_ALARM |
                                        AT91_RTC_SECEV | AT91_RTC_TIMEV |
                                        AT91_RTC_CALEV);

        clk_disable_unprepare(sclk);

        return 0;
}

static void at91_rtc_shutdown(struct platform_device *pdev)
{
        /* Disable all interrupts */
        at91_rtc_write(AT91_RTC_IDR, AT91_RTC_ACKUPD | AT91_RTC_ALARM |
                                        AT91_RTC_SECEV | AT91_RTC_TIMEV |
                                        AT91_RTC_CALEV);
}

#ifdef CONFIG_PM_SLEEP

/* AT91RM9200 RTC Power management control */

static int at91_rtc_suspend(struct device *dev)
{
        /* this IRQ is shared with DBGU and other hardware which isn't
         * necessarily doing PM like we are...
         */
        at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_ALARM);

        at91_rtc_imr = at91_rtc_read_imr()
                        & (AT91_RTC_ALARM|AT91_RTC_SECEV);
        if (at91_rtc_imr) {
                if (device_may_wakeup(dev)) {
                        unsigned long flags;

                        enable_irq_wake(irq);

                        spin_lock_irqsave(&suspended_lock, flags);
                        suspended = true;
                        spin_unlock_irqrestore(&suspended_lock, flags);
                } else {
                        at91_rtc_write_idr(at91_rtc_imr);
                }
        }
        return 0;
}

static int at91_rtc_resume(struct device *dev)
{
        struct rtc_device *rtc = dev_get_drvdata(dev);

        if (at91_rtc_imr) {
                if (device_may_wakeup(dev)) {
                        unsigned long flags;

                        spin_lock_irqsave(&suspended_lock, flags);

                        if (cached_events) {
                                rtc_update_irq(rtc, 1, cached_events);
                                cached_events = 0;
                        }

                        suspended = false;
                        spin_unlock_irqrestore(&suspended_lock, flags);

                        disable_irq_wake(irq);
                }
                at91_rtc_write_ier(at91_rtc_imr);
        }
        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(at91_rtc_pm_ops, at91_rtc_suspend, at91_rtc_resume);

static struct platform_driver at91_rtc_driver = {
        .remove         = __exit_p(at91_rtc_remove),
        .shutdown       = at91_rtc_shutdown,
        .driver         = {
                .name   = "at91_rtc",
                .pm     = &at91_rtc_pm_ops,
                .of_match_table = of_match_ptr(at91_rtc_dt_ids),
        },
};

module_platform_driver_probe(at91_rtc_driver, at91_rtc_probe);

MODULE_AUTHOR("Rick Bronson");
MODULE_DESCRIPTION("RTC driver for Atmel AT91RM9200");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:at91_rtc");