/*
 * TI OMAP1 Real Time Clock interface for Linux
 *
 * Copyright (C) 2003 MontaVista Software, Inc.
 * Author: George G. Davis <gdavis@mvista.com> or <source@mvista.com>
 *
 * Copyright (C) 2006 David Brownell (new RTC framework)
 *
 * 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/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/delay.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/platform_device.h>

#include <asm/io.h>


/* The OMAP1 RTC is a year/month/day/hours/minutes/seconds BCD clock
 * with century-range alarm matching, driven by the 32kHz clock.
 *
 * The main user-visible ways it differs from PC RTCs are by omitting
 * "don't care" alarm fields and sub-second periodic IRQs, and having
 * an autoadjust mechanism to calibrate to the true oscillator rate.
 *
 * Board-specific wiring options include using split power mode with
 * RTC_OFF_NOFF used as the reset signal (so the RTC won't be reset),
 * and wiring RTC_WAKE_INT (so the RTC alarm can wake the system from
 * low power modes) for OMAP1 boards (OMAP-L138 has this built into
 * the SoC). See the BOARD-SPECIFIC CUSTOMIZATION comment.
 */

#define OMAP_RTC_BASE                   0xfffb4800

/* RTC registers */
#define OMAP_RTC_SECONDS_REG            0x00
#define OMAP_RTC_MINUTES_REG            0x04
#define OMAP_RTC_HOURS_REG              0x08
#define OMAP_RTC_DAYS_REG               0x0C
#define OMAP_RTC_MONTHS_REG             0x10
#define OMAP_RTC_YEARS_REG              0x14
#define OMAP_RTC_WEEKS_REG              0x18

#define OMAP_RTC_ALARM_SECONDS_REG      0x20
#define OMAP_RTC_ALARM_MINUTES_REG      0x24
#define OMAP_RTC_ALARM_HOURS_REG        0x28
#define OMAP_RTC_ALARM_DAYS_REG         0x2c
#define OMAP_RTC_ALARM_MONTHS_REG       0x30
#define OMAP_RTC_ALARM_YEARS_REG        0x34

#define OMAP_RTC_CTRL_REG               0x40
#define OMAP_RTC_STATUS_REG             0x44
#define OMAP_RTC_INTERRUPTS_REG         0x48

#define OMAP_RTC_COMP_LSB_REG           0x4c
#define OMAP_RTC_COMP_MSB_REG           0x50
#define OMAP_RTC_OSC_REG                0x54

/* OMAP_RTC_CTRL_REG bit fields: */
#define OMAP_RTC_CTRL_SPLIT             (1<<7)
#define OMAP_RTC_CTRL_DISABLE           (1<<6)
#define OMAP_RTC_CTRL_SET_32_COUNTER    (1<<5)
#define OMAP_RTC_CTRL_TEST              (1<<4)
#define OMAP_RTC_CTRL_MODE_12_24        (1<<3)
#define OMAP_RTC_CTRL_AUTO_COMP         (1<<2)
#define OMAP_RTC_CTRL_ROUND_30S         (1<<1)
#define OMAP_RTC_CTRL_STOP              (1<<0)

/* OMAP_RTC_STATUS_REG bit fields: */
#define OMAP_RTC_STATUS_POWER_UP        (1<<7)
#define OMAP_RTC_STATUS_ALARM           (1<<6)
#define OMAP_RTC_STATUS_1D_EVENT        (1<<5)
#define OMAP_RTC_STATUS_1H_EVENT        (1<<4)
#define OMAP_RTC_STATUS_1M_EVENT        (1<<3)
#define OMAP_RTC_STATUS_1S_EVENT        (1<<2)
#define OMAP_RTC_STATUS_RUN             (1<<1)
#define OMAP_RTC_STATUS_BUSY            (1<<0)

/* OMAP_RTC_INTERRUPTS_REG bit fields: */
#define OMAP_RTC_INTERRUPTS_IT_ALARM    (1<<3)
#define OMAP_RTC_INTERRUPTS_IT_TIMER    (1<<2)

static void __iomem     *rtc_base;

#define rtc_read(addr)          __raw_readb(rtc_base + (addr))
#define rtc_write(val, addr)    __raw_writeb(val, rtc_base + (addr))


/* we rely on the rtc framework to handle locking (rtc->ops_lock),
 * so the only other requirement is that register accesses which
 * require BUSY to be clear are made with IRQs locally disabled
 */
static void rtc_wait_not_busy(void)
{
        int     count = 0;
        u8      status;

        /* BUSY may stay active for 1/32768 second (~30 usec) */
        for (count = 0; count < 50; count++) {
                status = rtc_read(OMAP_RTC_STATUS_REG);
                if ((status & (u8)OMAP_RTC_STATUS_BUSY) == 0)
                        break;
                udelay(1);
        }
        /* now we have ~15 usec to read/write various registers */
}

static irqreturn_t rtc_irq(int irq, void *rtc)
{
        unsigned long           events = 0;
        u8                      irq_data;

        irq_data = rtc_read(OMAP_RTC_STATUS_REG);

        /* alarm irq? */
        if (irq_data & OMAP_RTC_STATUS_ALARM) {
                rtc_write(OMAP_RTC_STATUS_ALARM, OMAP_RTC_STATUS_REG);
                events |= RTC_IRQF | RTC_AF;
        }

        /* 1/sec periodic/update irq? */
        if (irq_data & OMAP_RTC_STATUS_1S_EVENT)
                events |= RTC_IRQF | RTC_UF;

        rtc_update_irq(rtc, 1, events);

        return IRQ_HANDLED;
}

static int omap_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
        u8 reg;

        local_irq_disable();
        rtc_wait_not_busy();
        reg = rtc_read(OMAP_RTC_INTERRUPTS_REG);
        if (enabled)
                reg |= OMAP_RTC_INTERRUPTS_IT_ALARM;
        else
                reg &= ~OMAP_RTC_INTERRUPTS_IT_ALARM;
        rtc_wait_not_busy();
        rtc_write(reg, OMAP_RTC_INTERRUPTS_REG);
        local_irq_enable();

        return 0;
}

/* this hardware doesn't support "don't care" alarm fields */
static int tm2bcd(struct rtc_time *tm)
{
        if (rtc_valid_tm(tm) != 0)
                return -EINVAL;

        tm->tm_sec = bin2bcd(tm->tm_sec);
        tm->tm_min = bin2bcd(tm->tm_min);
        tm->tm_hour = bin2bcd(tm->tm_hour);
        tm->tm_mday = bin2bcd(tm->tm_mday);

        tm->tm_mon = bin2bcd(tm->tm_mon + 1);

        /* epoch == 1900 */
        if (tm->tm_year < 100 || tm->tm_year > 199)
                return -EINVAL;
        tm->tm_year = bin2bcd(tm->tm_year - 100);

        return 0;
}

static void bcd2tm(struct rtc_time *tm)
{
        tm->tm_sec = bcd2bin(tm->tm_sec);
        tm->tm_min = bcd2bin(tm->tm_min);
        tm->tm_hour = bcd2bin(tm->tm_hour);
        tm->tm_mday = bcd2bin(tm->tm_mday);
        tm->tm_mon = bcd2bin(tm->tm_mon) - 1;
        /* epoch == 1900 */
        tm->tm_year = bcd2bin(tm->tm_year) + 100;
}


static int omap_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        /* we don't report wday/yday/isdst ... */
        local_irq_disable();
        rtc_wait_not_busy();

        tm->tm_sec = rtc_read(OMAP_RTC_SECONDS_REG);
        tm->tm_min = rtc_read(OMAP_RTC_MINUTES_REG);
        tm->tm_hour = rtc_read(OMAP_RTC_HOURS_REG);
        tm->tm_mday = rtc_read(OMAP_RTC_DAYS_REG);
        tm->tm_mon = rtc_read(OMAP_RTC_MONTHS_REG);
        tm->tm_year = rtc_read(OMAP_RTC_YEARS_REG);

        local_irq_enable();

        bcd2tm(tm);
        return 0;
}

static int omap_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        if (tm2bcd(tm) < 0)
                return -EINVAL;
        local_irq_disable();
        rtc_wait_not_busy();

        rtc_write(tm->tm_year, OMAP_RTC_YEARS_REG);
        rtc_write(tm->tm_mon, OMAP_RTC_MONTHS_REG);
        rtc_write(tm->tm_mday, OMAP_RTC_DAYS_REG);
        rtc_write(tm->tm_hour, OMAP_RTC_HOURS_REG);
        rtc_write(tm->tm_min, OMAP_RTC_MINUTES_REG);
        rtc_write(tm->tm_sec, OMAP_RTC_SECONDS_REG);

        local_irq_enable();

        return 0;
}

static int omap_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
        local_irq_disable();
        rtc_wait_not_busy();

        alm->time.tm_sec = rtc_read(OMAP_RTC_ALARM_SECONDS_REG);
        alm->time.tm_min = rtc_read(OMAP_RTC_ALARM_MINUTES_REG);
        alm->time.tm_hour = rtc_read(OMAP_RTC_ALARM_HOURS_REG);
        alm->time.tm_mday = rtc_read(OMAP_RTC_ALARM_DAYS_REG);
        alm->time.tm_mon = rtc_read(OMAP_RTC_ALARM_MONTHS_REG);
        alm->time.tm_year = rtc_read(OMAP_RTC_ALARM_YEARS_REG);

        local_irq_enable();

        bcd2tm(&alm->time);
        alm->enabled = !!(rtc_read(OMAP_RTC_INTERRUPTS_REG)
                        & OMAP_RTC_INTERRUPTS_IT_ALARM);

        return 0;
}

static int omap_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
        u8 reg;

        if (tm2bcd(&alm->time) < 0)
                return -EINVAL;

        local_irq_disable();
        rtc_wait_not_busy();

        rtc_write(alm->time.tm_year, OMAP_RTC_ALARM_YEARS_REG);
        rtc_write(alm->time.tm_mon, OMAP_RTC_ALARM_MONTHS_REG);
        rtc_write(alm->time.tm_mday, OMAP_RTC_ALARM_DAYS_REG);
        rtc_write(alm->time.tm_hour, OMAP_RTC_ALARM_HOURS_REG);
        rtc_write(alm->time.tm_min, OMAP_RTC_ALARM_MINUTES_REG);
        rtc_write(alm->time.tm_sec, OMAP_RTC_ALARM_SECONDS_REG);

        reg = rtc_read(OMAP_RTC_INTERRUPTS_REG);
        if (alm->enabled)
                reg |= OMAP_RTC_INTERRUPTS_IT_ALARM;
        else
                reg &= ~OMAP_RTC_INTERRUPTS_IT_ALARM;
        rtc_write(reg, OMAP_RTC_INTERRUPTS_REG);

        local_irq_enable();

        return 0;
}

static struct rtc_class_ops omap_rtc_ops = {
        .read_time      = omap_rtc_read_time,
        .set_time       = omap_rtc_set_time,
        .read_alarm     = omap_rtc_read_alarm,
        .set_alarm      = omap_rtc_set_alarm,
        .alarm_irq_enable = omap_rtc_alarm_irq_enable,
};

static int omap_rtc_alarm;
static int omap_rtc_timer;

static int __init omap_rtc_probe(struct platform_device *pdev)
{
        struct resource         *res, *mem;
        struct rtc_device       *rtc;
        u8                      reg, new_ctrl;

        omap_rtc_timer = platform_get_irq(pdev, 0);
        if (omap_rtc_timer <= 0) {
                pr_debug("%s: no update irq?\n", pdev->name);
                return -ENOENT;
        }

        omap_rtc_alarm = platform_get_irq(pdev, 1);
        if (omap_rtc_alarm <= 0) {
                pr_debug("%s: no alarm irq?\n", pdev->name);
                return -ENOENT;
        }

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res) {
                pr_debug("%s: RTC resource data missing\n", pdev->name);
                return -ENOENT;
        }

        mem = request_mem_region(res->start, resource_size(res), pdev->name);
        if (!mem) {
                pr_debug("%s: RTC registers at %08x are not free\n",
                        pdev->name, res->start);
                return -EBUSY;
        }

        rtc_base = ioremap(res->start, resource_size(res));
        if (!rtc_base) {
                pr_debug("%s: RTC registers can't be mapped\n", pdev->name);
                goto fail;
        }

        rtc = rtc_device_register(pdev->name, &pdev->dev,
                        &omap_rtc_ops, THIS_MODULE);
        if (IS_ERR(rtc)) {
                pr_debug("%s: can't register RTC device, err %ld\n",
                        pdev->name, PTR_ERR(rtc));
                goto fail0;
        }
        platform_set_drvdata(pdev, rtc);
        dev_set_drvdata(&rtc->dev, mem);

        /* clear pending irqs, and set 1/second periodic,
         * which we'll use instead of update irqs
         */
        rtc_write(0, OMAP_RTC_INTERRUPTS_REG);

        /* clear old status */
        reg = rtc_read(OMAP_RTC_STATUS_REG);
        if (reg & (u8) OMAP_RTC_STATUS_POWER_UP) {
                pr_info("%s: RTC power up reset detected\n",
                        pdev->name);
                rtc_write(OMAP_RTC_STATUS_POWER_UP, OMAP_RTC_STATUS_REG);
        }
        if (reg & (u8) OMAP_RTC_STATUS_ALARM)
                rtc_write(OMAP_RTC_STATUS_ALARM, OMAP_RTC_STATUS_REG);

        /* handle periodic and alarm irqs */
        if (request_irq(omap_rtc_timer, rtc_irq, 0,
                        dev_name(&rtc->dev), rtc)) {
                pr_debug("%s: RTC timer interrupt IRQ%d already claimed\n",
                        pdev->name, omap_rtc_timer);
                goto fail1;
        }
        if ((omap_rtc_timer != omap_rtc_alarm) &&
                (request_irq(omap_rtc_alarm, rtc_irq, 0,
                        dev_name(&rtc->dev), rtc))) {
                pr_debug("%s: RTC alarm interrupt IRQ%d already claimed\n",
                        pdev->name, omap_rtc_alarm);
                goto fail2;
        }

        /* On boards with split power, RTC_ON_NOFF won't reset the RTC */
        reg = rtc_read(OMAP_RTC_CTRL_REG);
        if (reg & (u8) OMAP_RTC_CTRL_STOP)
                pr_info("%s: already running\n", pdev->name);

        /* force to 24 hour mode */
        new_ctrl = reg & (OMAP_RTC_CTRL_SPLIT|OMAP_RTC_CTRL_AUTO_COMP);
        new_ctrl |= OMAP_RTC_CTRL_STOP;

        /* BOARD-SPECIFIC CUSTOMIZATION CAN GO HERE:
         *
         *  - Device wake-up capability setting should come through chip
         *    init logic. OMAP1 boards should initialize the "wakeup capable"
         *    flag in the platform device if the board is wired right for
         *    being woken up by RTC alarm. For OMAP-L138, this capability
         *    is built into the SoC by the "Deep Sleep" capability.
         *
         *  - Boards wired so RTC_ON_nOFF is used as the reset signal,
         *    rather than nPWRON_RESET, should forcibly enable split
         *    power mode.  (Some chip errata report that RTC_CTRL_SPLIT
         *    is write-only, and always reads as zero...)
         */

        if (new_ctrl & (u8) OMAP_RTC_CTRL_SPLIT)
                pr_info("%s: split power mode\n", pdev->name);

        if (reg != new_ctrl)
                rtc_write(new_ctrl, OMAP_RTC_CTRL_REG);

        return 0;

fail2:
        free_irq(omap_rtc_timer, rtc);
fail1:
        rtc_device_unregister(rtc);
fail0:
        iounmap(rtc_base);
fail:
        release_mem_region(mem->start, resource_size(mem));
        return -EIO;
}

static int __exit omap_rtc_remove(struct platform_device *pdev)
{
        struct rtc_device       *rtc = platform_get_drvdata(pdev);
        struct resource         *mem = dev_get_drvdata(&rtc->dev);

        device_init_wakeup(&pdev->dev, 0);

        /* leave rtc running, but disable irqs */
        rtc_write(0, OMAP_RTC_INTERRUPTS_REG);

        free_irq(omap_rtc_timer, rtc);

        if (omap_rtc_timer != omap_rtc_alarm)
                free_irq(omap_rtc_alarm, rtc);

        rtc_device_unregister(rtc);
        iounmap(rtc_base);
        release_mem_region(mem->start, resource_size(mem));
        return 0;
}

#ifdef CONFIG_PM

static u8 irqstat;

static int omap_rtc_suspend(struct platform_device *pdev, pm_message_t state)
{
        irqstat = rtc_read(OMAP_RTC_INTERRUPTS_REG);

        /* FIXME the RTC alarm is not currently acting as a wakeup event
         * source, and in fact this enable() call is just saving a flag
         * that's never used...
         */
        if (device_may_wakeup(&pdev->dev))
                enable_irq_wake(omap_rtc_alarm);
        else
                rtc_write(0, OMAP_RTC_INTERRUPTS_REG);

        return 0;
}

static int omap_rtc_resume(struct platform_device *pdev)
{
        if (device_may_wakeup(&pdev->dev))
                disable_irq_wake(omap_rtc_alarm);
        else
                rtc_write(irqstat, OMAP_RTC_INTERRUPTS_REG);
        return 0;
}

#else
#define omap_rtc_suspend NULL
#define omap_rtc_resume  NULL
#endif

static void omap_rtc_shutdown(struct platform_device *pdev)
{
        rtc_write(0, OMAP_RTC_INTERRUPTS_REG);
}

MODULE_ALIAS("platform:omap_rtc");
static struct platform_driver omap_rtc_driver = {
        .remove         = __exit_p(omap_rtc_remove),
        .suspend        = omap_rtc_suspend,
        .resume         = omap_rtc_resume,
        .shutdown       = omap_rtc_shutdown,
        .driver         = {
                .name   = "omap_rtc",
                .owner  = THIS_MODULE,
        },
};

static int __init rtc_init(void)
{
        return platform_driver_probe(&omap_rtc_driver, omap_rtc_probe);
}
module_init(rtc_init);

static void __exit rtc_exit(void)
{
        platform_driver_unregister(&omap_rtc_driver);
}
module_exit(rtc_exit);

MODULE_AUTHOR("George G. Davis (and others)");
MODULE_LICENSE("GPL");