/*
 * SuperH On-Chip RTC Support
 *
 * Copyright (C) 2006 - 2009  Paul Mundt
 * Copyright (C) 2006  Jamie Lenehan
 * Copyright (C) 2008  Angelo Castello
 *
 * Based on the old arch/sh/kernel/cpu/rtc.c by:
 *
 *  Copyright (C) 2000  Philipp Rumpf <prumpf@tux.org>
 *  Copyright (C) 1999  Tetsuya Okada & Niibe Yutaka
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/bcd.h>
#include <linux/rtc.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/seq_file.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/io.h>
#include <linux/log2.h>
#include <linux/clk.h>
#include <asm/rtc.h>

#define DRV_NAME        "sh-rtc"
#define DRV_VERSION     "0.2.2"

#define RTC_REG(r)      ((r) * rtc_reg_size)

#define R64CNT          RTC_REG(0)

#define RSECCNT         RTC_REG(1)      /* RTC sec */
#define RMINCNT         RTC_REG(2)      /* RTC min */
#define RHRCNT          RTC_REG(3)      /* RTC hour */
#define RWKCNT          RTC_REG(4)      /* RTC week */
#define RDAYCNT         RTC_REG(5)      /* RTC day */
#define RMONCNT         RTC_REG(6)      /* RTC month */
#define RYRCNT          RTC_REG(7)      /* RTC year */
#define RSECAR          RTC_REG(8)      /* ALARM sec */
#define RMINAR          RTC_REG(9)      /* ALARM min */
#define RHRAR           RTC_REG(10)     /* ALARM hour */
#define RWKAR           RTC_REG(11)     /* ALARM week */
#define RDAYAR          RTC_REG(12)     /* ALARM day */
#define RMONAR          RTC_REG(13)     /* ALARM month */
#define RCR1            RTC_REG(14)     /* Control */
#define RCR2            RTC_REG(15)     /* Control */

/*
 * Note on RYRAR and RCR3: Up until this point most of the register
 * definitions are consistent across all of the available parts. However,
 * the placement of the optional RYRAR and RCR3 (the RYRAR control
 * register used to control RYRCNT/RYRAR compare) varies considerably
 * across various parts, occasionally being mapped in to a completely
 * unrelated address space. For proper RYRAR support a separate resource
 * would have to be handed off, but as this is purely optional in
 * practice, we simply opt not to support it, thereby keeping the code
 * quite a bit more simplified.
 */

/* ALARM Bits - or with BCD encoded value */
#define AR_ENB          0x80    /* Enable for alarm cmp   */

/* Period Bits */
#define PF_HP           0x100   /* Enable Half Period to support 8,32,128Hz */
#define PF_COUNT        0x200   /* Half periodic counter */
#define PF_OXS          0x400   /* Periodic One x Second */
#define PF_KOU          0x800   /* Kernel or User periodic request 1=kernel */
#define PF_MASK         0xf00

/* RCR1 Bits */
#define RCR1_CF         0x80    /* Carry Flag             */
#define RCR1_CIE        0x10    /* Carry Interrupt Enable */
#define RCR1_AIE        0x08    /* Alarm Interrupt Enable */
#define RCR1_AF         0x01    /* Alarm Flag             */

/* RCR2 Bits */
#define RCR2_PEF        0x80    /* PEriodic interrupt Flag */
#define RCR2_PESMASK    0x70    /* Periodic interrupt Set  */
#define RCR2_RTCEN      0x08    /* ENable RTC              */
#define RCR2_ADJ        0x04    /* ADJustment (30-second)  */
#define RCR2_RESET      0x02    /* Reset bit               */
#define RCR2_START      0x01    /* Start bit               */

struct sh_rtc {
        void __iomem            *regbase;
        unsigned long           regsize;
        struct resource         *res;
        int                     alarm_irq;
        int                     periodic_irq;
        int                     carry_irq;
        struct clk              *clk;
        struct rtc_device       *rtc_dev;
        spinlock_t              lock;
        unsigned long           capabilities;   /* See asm/rtc.h for cap bits */
        unsigned short          periodic_freq;
};

static int __sh_rtc_interrupt(struct sh_rtc *rtc)
{
        unsigned int tmp, pending;

        tmp = readb(rtc->regbase + RCR1);
        pending = tmp & RCR1_CF;
        tmp &= ~RCR1_CF;
        writeb(tmp, rtc->regbase + RCR1);

        /* Users have requested One x Second IRQ */
        if (pending && rtc->periodic_freq & PF_OXS)
                rtc_update_irq(rtc->rtc_dev, 1, RTC_UF | RTC_IRQF);

        return pending;
}

static int __sh_rtc_alarm(struct sh_rtc *rtc)
{
        unsigned int tmp, pending;

        tmp = readb(rtc->regbase + RCR1);
        pending = tmp & RCR1_AF;
        tmp &= ~(RCR1_AF | RCR1_AIE);
        writeb(tmp, rtc->regbase + RCR1);

        if (pending)
                rtc_update_irq(rtc->rtc_dev, 1, RTC_AF | RTC_IRQF);

        return pending;
}

static int __sh_rtc_periodic(struct sh_rtc *rtc)
{
        struct rtc_device *rtc_dev = rtc->rtc_dev;
        struct rtc_task *irq_task;
        unsigned int tmp, pending;

        tmp = readb(rtc->regbase + RCR2);
        pending = tmp & RCR2_PEF;
        tmp &= ~RCR2_PEF;
        writeb(tmp, rtc->regbase + RCR2);

        if (!pending)
                return 0;

        /* Half period enabled than one skipped and the next notified */
        if ((rtc->periodic_freq & PF_HP) && (rtc->periodic_freq & PF_COUNT))
                rtc->periodic_freq &= ~PF_COUNT;
        else {
                if (rtc->periodic_freq & PF_HP)
                        rtc->periodic_freq |= PF_COUNT;
                if (rtc->periodic_freq & PF_KOU) {
                        spin_lock(&rtc_dev->irq_task_lock);
                        irq_task = rtc_dev->irq_task;
                        if (irq_task)
                                irq_task->func(irq_task->private_data);
                        spin_unlock(&rtc_dev->irq_task_lock);
                } else
                        rtc_update_irq(rtc->rtc_dev, 1, RTC_PF | RTC_IRQF);
        }

        return pending;
}

static irqreturn_t sh_rtc_interrupt(int irq, void *dev_id)
{
        struct sh_rtc *rtc = dev_id;
        int ret;

        spin_lock(&rtc->lock);
        ret = __sh_rtc_interrupt(rtc);
        spin_unlock(&rtc->lock);

        return IRQ_RETVAL(ret);
}

static irqreturn_t sh_rtc_alarm(int irq, void *dev_id)
{
        struct sh_rtc *rtc = dev_id;
        int ret;

        spin_lock(&rtc->lock);
        ret = __sh_rtc_alarm(rtc);
        spin_unlock(&rtc->lock);

        return IRQ_RETVAL(ret);
}

static irqreturn_t sh_rtc_periodic(int irq, void *dev_id)
{
        struct sh_rtc *rtc = dev_id;
        int ret;

        spin_lock(&rtc->lock);
        ret = __sh_rtc_periodic(rtc);
        spin_unlock(&rtc->lock);

        return IRQ_RETVAL(ret);
}

static irqreturn_t sh_rtc_shared(int irq, void *dev_id)
{
        struct sh_rtc *rtc = dev_id;
        int ret;

        spin_lock(&rtc->lock);
        ret = __sh_rtc_interrupt(rtc);
        ret |= __sh_rtc_alarm(rtc);
        ret |= __sh_rtc_periodic(rtc);
        spin_unlock(&rtc->lock);

        return IRQ_RETVAL(ret);
}

static inline void sh_rtc_setpie(struct device *dev, unsigned int enable)
{
        struct sh_rtc *rtc = dev_get_drvdata(dev);
        unsigned int tmp;

        spin_lock_irq(&rtc->lock);

        tmp = readb(rtc->regbase + RCR2);

        if (enable) {
                tmp &= ~RCR2_PEF;       /* Clear PES bit */
                tmp |= (rtc->periodic_freq & ~PF_HP);   /* Set PES2-0 */
        } else
                tmp &= ~(RCR2_PESMASK | RCR2_PEF);

        writeb(tmp, rtc->regbase + RCR2);

        spin_unlock_irq(&rtc->lock);
}

static inline int sh_rtc_setfreq(struct device *dev, unsigned int freq)
{
        struct sh_rtc *rtc = dev_get_drvdata(dev);
        int tmp, ret = 0;

        spin_lock_irq(&rtc->lock);
        tmp = rtc->periodic_freq & PF_MASK;

        switch (freq) {
        case 0:
                rtc->periodic_freq = 0x00;
                break;
        case 1:
                rtc->periodic_freq = 0x60;
                break;
        case 2:
                rtc->periodic_freq = 0x50;
                break;
        case 4:
                rtc->periodic_freq = 0x40;
                break;
        case 8:
                rtc->periodic_freq = 0x30 | PF_HP;
                break;
        case 16:
                rtc->periodic_freq = 0x30;
                break;
        case 32:
                rtc->periodic_freq = 0x20 | PF_HP;
                break;
        case 64:
                rtc->periodic_freq = 0x20;
                break;
        case 128:
                rtc->periodic_freq = 0x10 | PF_HP;
                break;
        case 256:
                rtc->periodic_freq = 0x10;
                break;
        default:
                ret = -ENOTSUPP;
        }

        if (ret == 0) {
                rtc->periodic_freq |= tmp;
                rtc->rtc_dev->irq_freq = freq;
        }

        spin_unlock_irq(&rtc->lock);
        return ret;
}

static inline void sh_rtc_setaie(struct device *dev, unsigned int enable)
{
        struct sh_rtc *rtc = dev_get_drvdata(dev);
        unsigned int tmp;

        spin_lock_irq(&rtc->lock);

        tmp = readb(rtc->regbase + RCR1);

        if (enable)
                tmp |= RCR1_AIE;
        else
                tmp &= ~RCR1_AIE;

        writeb(tmp, rtc->regbase + RCR1);

        spin_unlock_irq(&rtc->lock);
}

static int sh_rtc_proc(struct device *dev, struct seq_file *seq)
{
        struct sh_rtc *rtc = dev_get_drvdata(dev);
        unsigned int tmp;

        tmp = readb(rtc->regbase + RCR1);
        seq_printf(seq, "carry_IRQ\t: %s\n", (tmp & RCR1_CIE) ? "yes" : "no");

        tmp = readb(rtc->regbase + RCR2);
        seq_printf(seq, "periodic_IRQ\t: %s\n",
                   (tmp & RCR2_PESMASK) ? "yes" : "no");

        return 0;
}

static inline void sh_rtc_setcie(struct device *dev, unsigned int enable)
{
        struct sh_rtc *rtc = dev_get_drvdata(dev);
        unsigned int tmp;

        spin_lock_irq(&rtc->lock);

        tmp = readb(rtc->regbase + RCR1);

        if (!enable)
                tmp &= ~RCR1_CIE;
        else
                tmp |= RCR1_CIE;

        writeb(tmp, rtc->regbase + RCR1);

        spin_unlock_irq(&rtc->lock);
}

static int sh_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
{
        struct sh_rtc *rtc = dev_get_drvdata(dev);
        unsigned int ret = 0;

        switch (cmd) {
        case RTC_PIE_OFF:
        case RTC_PIE_ON:
                sh_rtc_setpie(dev, cmd == RTC_PIE_ON);
                break;
        case RTC_AIE_OFF:
        case RTC_AIE_ON:
                sh_rtc_setaie(dev, cmd == RTC_AIE_ON);
                break;
        case RTC_UIE_OFF:
                rtc->periodic_freq &= ~PF_OXS;
                sh_rtc_setcie(dev, 0);
                break;
        case RTC_UIE_ON:
                rtc->periodic_freq |= PF_OXS;
                sh_rtc_setcie(dev, 1);
                break;
        case RTC_IRQP_READ:
                ret = put_user(rtc->rtc_dev->irq_freq,
                               (unsigned long __user *)arg);
                break;
        case RTC_IRQP_SET:
                ret = sh_rtc_setfreq(dev, arg);
                break;
        default:
                ret = -ENOIOCTLCMD;
        }

        return ret;
}

static int sh_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct sh_rtc *rtc = platform_get_drvdata(pdev);
        unsigned int sec128, sec2, yr, yr100, cf_bit;

        do {
                unsigned int tmp;

                spin_lock_irq(&rtc->lock);

                tmp = readb(rtc->regbase + RCR1);
                tmp &= ~RCR1_CF; /* Clear CF-bit */
                tmp |= RCR1_CIE;
                writeb(tmp, rtc->regbase + RCR1);

                sec128 = readb(rtc->regbase + R64CNT);

                tm->tm_sec      = bcd2bin(readb(rtc->regbase + RSECCNT));
                tm->tm_min      = bcd2bin(readb(rtc->regbase + RMINCNT));
                tm->tm_hour     = bcd2bin(readb(rtc->regbase + RHRCNT));
                tm->tm_wday     = bcd2bin(readb(rtc->regbase + RWKCNT));
                tm->tm_mday     = bcd2bin(readb(rtc->regbase + RDAYCNT));
                tm->tm_mon      = bcd2bin(readb(rtc->regbase + RMONCNT)) - 1;

                if (rtc->capabilities & RTC_CAP_4_DIGIT_YEAR) {
                        yr  = readw(rtc->regbase + RYRCNT);
                        yr100 = bcd2bin(yr >> 8);
                        yr &= 0xff;
                } else {
                        yr  = readb(rtc->regbase + RYRCNT);
                        yr100 = bcd2bin((yr == 0x99) ? 0x19 : 0x20);
                }

                tm->tm_year = (yr100 * 100 + bcd2bin(yr)) - 1900;

                sec2 = readb(rtc->regbase + R64CNT);
                cf_bit = readb(rtc->regbase + RCR1) & RCR1_CF;

                spin_unlock_irq(&rtc->lock);
        } while (cf_bit != 0 || ((sec128 ^ sec2) & RTC_BIT_INVERTED) != 0);

#if RTC_BIT_INVERTED != 0
        if ((sec128 & RTC_BIT_INVERTED))
                tm->tm_sec--;
#endif

        /* only keep the carry interrupt enabled if UIE is on */
        if (!(rtc->periodic_freq & PF_OXS))
                sh_rtc_setcie(dev, 0);

        dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
                "mday=%d, mon=%d, year=%d, wday=%d\n",
                __func__,
                tm->tm_sec, tm->tm_min, tm->tm_hour,
                tm->tm_mday, tm->tm_mon + 1, tm->tm_year, tm->tm_wday);

        return rtc_valid_tm(tm);
}

static int sh_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct sh_rtc *rtc = platform_get_drvdata(pdev);
        unsigned int tmp;
        int year;

        spin_lock_irq(&rtc->lock);

        /* Reset pre-scaler & stop RTC */
        tmp = readb(rtc->regbase + RCR2);
        tmp |= RCR2_RESET;
        tmp &= ~RCR2_START;
        writeb(tmp, rtc->regbase + RCR2);

        writeb(bin2bcd(tm->tm_sec),  rtc->regbase + RSECCNT);
        writeb(bin2bcd(tm->tm_min),  rtc->regbase + RMINCNT);
        writeb(bin2bcd(tm->tm_hour), rtc->regbase + RHRCNT);
        writeb(bin2bcd(tm->tm_wday), rtc->regbase + RWKCNT);
        writeb(bin2bcd(tm->tm_mday), rtc->regbase + RDAYCNT);
        writeb(bin2bcd(tm->tm_mon + 1), rtc->regbase + RMONCNT);

        if (rtc->capabilities & RTC_CAP_4_DIGIT_YEAR) {
                year = (bin2bcd((tm->tm_year + 1900) / 100) << 8) |
                        bin2bcd(tm->tm_year % 100);
                writew(year, rtc->regbase + RYRCNT);
        } else {
                year = tm->tm_year % 100;
                writeb(bin2bcd(year), rtc->regbase + RYRCNT);
        }

        /* Start RTC */
        tmp = readb(rtc->regbase + RCR2);
        tmp &= ~RCR2_RESET;
        tmp |= RCR2_RTCEN | RCR2_START;
        writeb(tmp, rtc->regbase + RCR2);

        spin_unlock_irq(&rtc->lock);

        return 0;
}

static inline int sh_rtc_read_alarm_value(struct sh_rtc *rtc, int reg_off)
{
        unsigned int byte;
        int value = 0xff;       /* return 0xff for ignored values */

        byte = readb(rtc->regbase + reg_off);
        if (byte & AR_ENB) {
                byte &= ~AR_ENB;        /* strip the enable bit */
                value = bcd2bin(byte);
        }

        return value;
}

static int sh_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct sh_rtc *rtc = platform_get_drvdata(pdev);
        struct rtc_time *tm = &wkalrm->time;

        spin_lock_irq(&rtc->lock);

        tm->tm_sec      = sh_rtc_read_alarm_value(rtc, RSECAR);
        tm->tm_min      = sh_rtc_read_alarm_value(rtc, RMINAR);
        tm->tm_hour     = sh_rtc_read_alarm_value(rtc, RHRAR);
        tm->tm_wday     = sh_rtc_read_alarm_value(rtc, RWKAR);
        tm->tm_mday     = sh_rtc_read_alarm_value(rtc, RDAYAR);
        tm->tm_mon      = sh_rtc_read_alarm_value(rtc, RMONAR);
        if (tm->tm_mon > 0)
                tm->tm_mon -= 1; /* RTC is 1-12, tm_mon is 0-11 */
        tm->tm_year     = 0xffff;

        wkalrm->enabled = (readb(rtc->regbase + RCR1) & RCR1_AIE) ? 1 : 0;

        spin_unlock_irq(&rtc->lock);

        return 0;
}

static inline void sh_rtc_write_alarm_value(struct sh_rtc *rtc,
                                            int value, int reg_off)
{
        /* < 0 for a value that is ignored */
        if (value < 0)
                writeb(0, rtc->regbase + reg_off);
        else
                writeb(bin2bcd(value) | AR_ENB,  rtc->regbase + reg_off);
}

static int sh_rtc_check_alarm(struct rtc_time *tm)
{
        /*
         * The original rtc says anything > 0xc0 is "don't care" or "match
         * all" - most users use 0xff but rtc-dev uses -1 for the same thing.
         * The original rtc doesn't support years - some things use -1 and
         * some 0xffff. We use -1 to make out tests easier.
         */
        if (tm->tm_year == 0xffff)
                tm->tm_year = -1;
        if (tm->tm_mon >= 0xff)
                tm->tm_mon = -1;
        if (tm->tm_mday >= 0xff)
                tm->tm_mday = -1;
        if (tm->tm_wday >= 0xff)
                tm->tm_wday = -1;
        if (tm->tm_hour >= 0xff)
                tm->tm_hour = -1;
        if (tm->tm_min >= 0xff)
                tm->tm_min = -1;
        if (tm->tm_sec >= 0xff)
                tm->tm_sec = -1;

        if (tm->tm_year > 9999 ||
                tm->tm_mon >= 12 ||
                tm->tm_mday == 0 || tm->tm_mday >= 32 ||
                tm->tm_wday >= 7 ||
                tm->tm_hour >= 24 ||
                tm->tm_min >= 60 ||
                tm->tm_sec >= 60)
                return -EINVAL;

        return 0;
}

static int sh_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct sh_rtc *rtc = platform_get_drvdata(pdev);
        unsigned int rcr1;
        struct rtc_time *tm = &wkalrm->time;
        int mon, err;

        err = sh_rtc_check_alarm(tm);
        if (unlikely(err < 0))
                return err;

        spin_lock_irq(&rtc->lock);

        /* disable alarm interrupt and clear the alarm flag */
        rcr1 = readb(rtc->regbase + RCR1);
        rcr1 &= ~(RCR1_AF | RCR1_AIE);
        writeb(rcr1, rtc->regbase + RCR1);

        /* set alarm time */
        sh_rtc_write_alarm_value(rtc, tm->tm_sec,  RSECAR);
        sh_rtc_write_alarm_value(rtc, tm->tm_min,  RMINAR);
        sh_rtc_write_alarm_value(rtc, tm->tm_hour, RHRAR);
        sh_rtc_write_alarm_value(rtc, tm->tm_wday, RWKAR);
        sh_rtc_write_alarm_value(rtc, tm->tm_mday, RDAYAR);
        mon = tm->tm_mon;
        if (mon >= 0)
                mon += 1;
        sh_rtc_write_alarm_value(rtc, mon, RMONAR);

        if (wkalrm->enabled) {
                rcr1 |= RCR1_AIE;
                writeb(rcr1, rtc->regbase + RCR1);
        }

        spin_unlock_irq(&rtc->lock);

        return 0;
}

static int sh_rtc_irq_set_state(struct device *dev, int enabled)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct sh_rtc *rtc = platform_get_drvdata(pdev);

        if (enabled) {
                rtc->periodic_freq |= PF_KOU;
                return sh_rtc_ioctl(dev, RTC_PIE_ON, 0);
        } else {
                rtc->periodic_freq &= ~PF_KOU;
                return sh_rtc_ioctl(dev, RTC_PIE_OFF, 0);
        }
}

static int sh_rtc_irq_set_freq(struct device *dev, int freq)
{
        if (!is_power_of_2(freq))
                return -EINVAL;

        return sh_rtc_ioctl(dev, RTC_IRQP_SET, freq);
}

static struct rtc_class_ops sh_rtc_ops = {
        .ioctl          = sh_rtc_ioctl,
        .read_time      = sh_rtc_read_time,
        .set_time       = sh_rtc_set_time,
        .read_alarm     = sh_rtc_read_alarm,
        .set_alarm      = sh_rtc_set_alarm,
        .irq_set_state  = sh_rtc_irq_set_state,
        .irq_set_freq   = sh_rtc_irq_set_freq,
        .proc           = sh_rtc_proc,
};

static int __devinit sh_rtc_probe(struct platform_device *pdev)
{
        struct sh_rtc *rtc;
        struct resource *res;
        struct rtc_time r;
        char clk_name[6];
        int clk_id, ret;

        rtc = kzalloc(sizeof(struct sh_rtc), GFP_KERNEL);
        if (unlikely(!rtc))
                return -ENOMEM;

        spin_lock_init(&rtc->lock);

        /* get periodic/carry/alarm irqs */
        ret = platform_get_irq(pdev, 0);
        if (unlikely(ret <= 0)) {
                ret = -ENOENT;
                dev_err(&pdev->dev, "No IRQ resource\n");
                goto err_badres;
        }

        rtc->periodic_irq = ret;
        rtc->carry_irq = platform_get_irq(pdev, 1);
        rtc->alarm_irq = platform_get_irq(pdev, 2);

        res = platform_get_resource(pdev, IORESOURCE_IO, 0);
        if (unlikely(res == NULL)) {
                ret = -ENOENT;
                dev_err(&pdev->dev, "No IO resource\n");
                goto err_badres;
        }

        rtc->regsize = resource_size(res);

        rtc->res = request_mem_region(res->start, rtc->regsize, pdev->name);
        if (unlikely(!rtc->res)) {
                ret = -EBUSY;
                goto err_badres;
        }

        rtc->regbase = ioremap_nocache(rtc->res->start, rtc->regsize);
        if (unlikely(!rtc->regbase)) {
                ret = -EINVAL;
                goto err_badmap;
        }

        clk_id = pdev->id;
        /* With a single device, the clock id is still "rtc0" */
        if (clk_id < 0)
                clk_id = 0;

        snprintf(clk_name, sizeof(clk_name), "rtc%d", clk_id);

        rtc->clk = clk_get(&pdev->dev, clk_name);
        if (IS_ERR(rtc->clk)) {
                /*
                 * No error handling for rtc->clk intentionally, not all
                 * platforms will have a unique clock for the RTC, and
                 * the clk API can handle the struct clk pointer being
                 * NULL.
                 */
                rtc->clk = NULL;
        }

        clk_enable(rtc->clk);

        rtc->rtc_dev = rtc_device_register("sh", &pdev->dev,
                                           &sh_rtc_ops, THIS_MODULE);
        if (IS_ERR(rtc->rtc_dev)) {
                ret = PTR_ERR(rtc->rtc_dev);
                goto err_unmap;
        }

        rtc->capabilities = RTC_DEF_CAPABILITIES;
        if (pdev->dev.platform_data) {
                struct sh_rtc_platform_info *pinfo = pdev->dev.platform_data;

                /*
                 * Some CPUs have special capabilities in addition to the
                 * default set. Add those in here.
                 */
                rtc->capabilities |= pinfo->capabilities;
        }

        rtc->rtc_dev->max_user_freq = 256;

        platform_set_drvdata(pdev, rtc);

        if (rtc->carry_irq <= 0) {
                /* register shared periodic/carry/alarm irq */
                ret = request_irq(rtc->periodic_irq, sh_rtc_shared,
                                  IRQF_DISABLED, "sh-rtc", rtc);
                if (unlikely(ret)) {
                        dev_err(&pdev->dev,
                                "request IRQ failed with %d, IRQ %d\n", ret,
                                rtc->periodic_irq);
                        goto err_unmap;
                }
        } else {
                /* register periodic/carry/alarm irqs */
                ret = request_irq(rtc->periodic_irq, sh_rtc_periodic,
                                  IRQF_DISABLED, "sh-rtc period", rtc);
                if (unlikely(ret)) {
                        dev_err(&pdev->dev,
                                "request period IRQ failed with %d, IRQ %d\n",
                                ret, rtc->periodic_irq);
                        goto err_unmap;
                }

                ret = request_irq(rtc->carry_irq, sh_rtc_interrupt,
                                  IRQF_DISABLED, "sh-rtc carry", rtc);
                if (unlikely(ret)) {
                        dev_err(&pdev->dev,
                                "request carry IRQ failed with %d, IRQ %d\n",
                                ret, rtc->carry_irq);
                        free_irq(rtc->periodic_irq, rtc);
                        goto err_unmap;
                }

                ret = request_irq(rtc->alarm_irq, sh_rtc_alarm,
                                  IRQF_DISABLED, "sh-rtc alarm", rtc);
                if (unlikely(ret)) {
                        dev_err(&pdev->dev,
                                "request alarm IRQ failed with %d, IRQ %d\n",
                                ret, rtc->alarm_irq);
                        free_irq(rtc->carry_irq, rtc);
                        free_irq(rtc->periodic_irq, rtc);
                        goto err_unmap;
                }
        }

        /* everything disabled by default */
        rtc->periodic_freq = 0;
        rtc->rtc_dev->irq_freq = 0;
        sh_rtc_setpie(&pdev->dev, 0);
        sh_rtc_setaie(&pdev->dev, 0);
        sh_rtc_setcie(&pdev->dev, 0);

        /* reset rtc to epoch 0 if time is invalid */
        if (rtc_read_time(rtc->rtc_dev, &r) < 0) {
                rtc_time_to_tm(0, &r);
                rtc_set_time(rtc->rtc_dev, &r);
        }

        device_init_wakeup(&pdev->dev, 1);
        return 0;

err_unmap:
        clk_disable(rtc->clk);
        clk_put(rtc->clk);
        iounmap(rtc->regbase);
err_badmap:
        release_resource(rtc->res);
err_badres:
        kfree(rtc);

        return ret;
}

static int __devexit sh_rtc_remove(struct platform_device *pdev)
{
        struct sh_rtc *rtc = platform_get_drvdata(pdev);

        if (likely(rtc->rtc_dev))
                rtc_device_unregister(rtc->rtc_dev);

        sh_rtc_setpie(&pdev->dev, 0);
        sh_rtc_setaie(&pdev->dev, 0);
        sh_rtc_setcie(&pdev->dev, 0);

        free_irq(rtc->periodic_irq, rtc);

        if (rtc->carry_irq > 0) {
                free_irq(rtc->carry_irq, rtc);
                free_irq(rtc->alarm_irq, rtc);
        }

        release_resource(rtc->res);

        iounmap(rtc->regbase);

        clk_disable(rtc->clk);
        clk_put(rtc->clk);

        platform_set_drvdata(pdev, NULL);

        kfree(rtc);

        return 0;
}

static void sh_rtc_set_irq_wake(struct device *dev, int enabled)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct sh_rtc *rtc = platform_get_drvdata(pdev);

        set_irq_wake(rtc->periodic_irq, enabled);

        if (rtc->carry_irq > 0) {
                set_irq_wake(rtc->carry_irq, enabled);
                set_irq_wake(rtc->alarm_irq, enabled);
        }
}

static int sh_rtc_suspend(struct device *dev)
{
        if (device_may_wakeup(dev))
                sh_rtc_set_irq_wake(dev, 1);

        return 0;
}

static int sh_rtc_resume(struct device *dev)
{
        if (device_may_wakeup(dev))
                sh_rtc_set_irq_wake(dev, 0);

        return 0;
}

static struct dev_pm_ops sh_rtc_dev_pm_ops = {
        .suspend = sh_rtc_suspend,
        .resume = sh_rtc_resume,
};

static struct platform_driver sh_rtc_platform_driver = {
        .driver         = {
                .name   = DRV_NAME,
                .owner  = THIS_MODULE,
                .pm     = &sh_rtc_dev_pm_ops,
        },
        .probe          = sh_rtc_probe,
        .remove         = __devexit_p(sh_rtc_remove),
};

static int __init sh_rtc_init(void)
{
        return platform_driver_register(&sh_rtc_platform_driver);
}

static void __exit sh_rtc_exit(void)
{
        platform_driver_unregister(&sh_rtc_platform_driver);
}

module_init(sh_rtc_init);
module_exit(sh_rtc_exit);

MODULE_DESCRIPTION("SuperH on-chip RTC driver");
MODULE_VERSION(DRV_VERSION);
MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>, "
              "Jamie Lenehan <lenehan@twibble.org>, "
              "Angelo Castello <angelo.castello@st.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRV_NAME);