/*
 * Ricoh RS5C313 RTC device/driver
 *  Copyright (C) 2007 Nobuhiro Iwamatsu
 *
 *  2005-09-19 modified by kogiidena
 *
 * Based on the old drivers/char/rs5c313_rtc.c  by:
 *  Copyright (C) 2000 Philipp Rumpf <prumpf@tux.org>
 *  Copyright (C) 1999 Tetsuya Okada & Niibe Yutaka
 *
 * Based on code written by Paul Gortmaker.
 *  Copyright (C) 1996 Paul Gortmaker
 *
 * 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.
 *
 * Based on other minimal char device drivers, like Alan's
 * watchdog, Ted's random, etc. etc.
 *
 *      1.07    Paul Gortmaker.
 *      1.08    Miquel van Smoorenburg: disallow certain things on the
 *              DEC Alpha as the CMOS clock is also used for other things.
 *      1.09    Nikita Schmidt: epoch support and some Alpha cleanup.
 *      1.09a   Pete Zaitcev: Sun SPARC
 *      1.09b   Jeff Garzik: Modularize, init cleanup
 *      1.09c   Jeff Garzik: SMP cleanup
 *      1.10    Paul Barton-Davis: add support for async I/O
 *      1.10a   Andrea Arcangeli: Alpha updates
 *      1.10b   Andrew Morton: SMP lock fix
 *      1.10c   Cesar Barros: SMP locking fixes and cleanup
 *      1.10d   Paul Gortmaker: delete paranoia check in rtc_exit
 *      1.10e   Maciej W. Rozycki: Handle DECstation's year weirdness.
 *      1.11    Takashi Iwai: Kernel access functions
 *                            rtc_register/rtc_unregister/rtc_control
 *      1.11a   Daniele Bellucci: Audit create_proc_read_entry in rtc_init
 *      1.12    Venkatesh Pallipadi: Hooks for emulating rtc on HPET base-timer
 *              CONFIG_HPET_EMULATE_RTC
 *      1.13    Nobuhiro Iwamatsu: Update driver.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/err.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>
#include <linux/bcd.h>
#include <linux/delay.h>
#include <linux/io.h>

#define DRV_NAME        "rs5c313"

#ifdef CONFIG_SH_LANDISK
/*****************************************************/
/* LANDISK dependence part of RS5C313                */
/*****************************************************/

#define SCSMR1          0xFFE00000
#define SCSCR1          0xFFE00008
#define SCSMR1_CA       0x80
#define SCSCR1_CKE      0x03
#define SCSPTR1         0xFFE0001C
#define SCSPTR1_EIO     0x80
#define SCSPTR1_SPB1IO  0x08
#define SCSPTR1_SPB1DT  0x04
#define SCSPTR1_SPB0IO  0x02
#define SCSPTR1_SPB0DT  0x01

#define SDA_OEN         SCSPTR1_SPB1IO
#define SDA             SCSPTR1_SPB1DT
#define SCL_OEN         SCSPTR1_SPB0IO
#define SCL             SCSPTR1_SPB0DT

/* RICOH RS5C313 CE port */
#define RS5C313_CE      0xB0000003

/* RICOH RS5C313 CE port bit */
#define RS5C313_CE_RTCCE        0x02

/* SCSPTR1 data */
unsigned char scsptr1_data;

#define RS5C313_CEENABLE    __raw_writeb(RS5C313_CE_RTCCE, RS5C313_CE);
#define RS5C313_CEDISABLE   __raw_writeb(0x00, RS5C313_CE)
#define RS5C313_MISCOP      __raw_writeb(0x02, 0xB0000008)

static void rs5c313_init_port(void)
{
        /* Set SCK as I/O port and Initialize SCSPTR1 data & I/O port. */
        __raw_writeb(__raw_readb(SCSMR1) & ~SCSMR1_CA, SCSMR1);
        __raw_writeb(__raw_readb(SCSCR1) & ~SCSCR1_CKE, SCSCR1);

        /* And Initialize SCL for RS5C313 clock */
        scsptr1_data = __raw_readb(SCSPTR1) | SCL;      /* SCL:H */
        __raw_writeb(scsptr1_data, SCSPTR1);
        scsptr1_data = __raw_readb(SCSPTR1) | SCL_OEN;  /* SCL output enable */
        __raw_writeb(scsptr1_data, SCSPTR1);
        RS5C313_CEDISABLE;      /* CE:L */
}

static void rs5c313_write_data(unsigned char data)
{
        int i;

        for (i = 0; i < 8; i++) {
                /* SDA:Write Data */
                scsptr1_data = (scsptr1_data & ~SDA) |
                                ((((0x80 >> i) & data) >> (7 - i)) << 2);
                __raw_writeb(scsptr1_data, SCSPTR1);
                if (i == 0) {
                        scsptr1_data |= SDA_OEN;        /* SDA:output enable */
                        __raw_writeb(scsptr1_data, SCSPTR1);
                }
                ndelay(700);
                scsptr1_data &= ~SCL;   /* SCL:L */
                __raw_writeb(scsptr1_data, SCSPTR1);
                ndelay(700);
                scsptr1_data |= SCL;    /* SCL:H */
                __raw_writeb(scsptr1_data, SCSPTR1);
        }

        scsptr1_data &= ~SDA_OEN;       /* SDA:output disable */
        __raw_writeb(scsptr1_data, SCSPTR1);
}

static unsigned char rs5c313_read_data(void)
{
        int i;
        unsigned char data = 0;

        for (i = 0; i < 8; i++) {
                ndelay(700);
                /* SDA:Read Data */
                data |= ((__raw_readb(SCSPTR1) & SDA) >> 2) << (7 - i);
                scsptr1_data &= ~SCL;   /* SCL:L */
                __raw_writeb(scsptr1_data, SCSPTR1);
                ndelay(700);
                scsptr1_data |= SCL;    /* SCL:H */
                __raw_writeb(scsptr1_data, SCSPTR1);
        }
        return data & 0x0F;
}

#endif /* CONFIG_SH_LANDISK */

/*****************************************************/
/* machine independence part of RS5C313              */
/*****************************************************/

/* RICOH RS5C313 address */
#define RS5C313_ADDR_SEC        0x00
#define RS5C313_ADDR_SEC10      0x01
#define RS5C313_ADDR_MIN        0x02
#define RS5C313_ADDR_MIN10      0x03
#define RS5C313_ADDR_HOUR       0x04
#define RS5C313_ADDR_HOUR10     0x05
#define RS5C313_ADDR_WEEK       0x06
#define RS5C313_ADDR_INTINTVREG 0x07
#define RS5C313_ADDR_DAY        0x08
#define RS5C313_ADDR_DAY10      0x09
#define RS5C313_ADDR_MON        0x0A
#define RS5C313_ADDR_MON10      0x0B
#define RS5C313_ADDR_YEAR       0x0C
#define RS5C313_ADDR_YEAR10     0x0D
#define RS5C313_ADDR_CNTREG     0x0E
#define RS5C313_ADDR_TESTREG    0x0F

/* RICOH RS5C313 control register */
#define RS5C313_CNTREG_ADJ_BSY  0x01
#define RS5C313_CNTREG_WTEN_XSTP        0x02
#define RS5C313_CNTREG_12_24    0x04
#define RS5C313_CNTREG_CTFG     0x08

/* RICOH RS5C313 test register */
#define RS5C313_TESTREG_TEST    0x01

/* RICOH RS5C313 control bit */
#define RS5C313_CNTBIT_READ     0x40
#define RS5C313_CNTBIT_AD       0x20
#define RS5C313_CNTBIT_DT       0x10

static unsigned char rs5c313_read_reg(unsigned char addr)
{

        rs5c313_write_data(addr | RS5C313_CNTBIT_READ | RS5C313_CNTBIT_AD);
        return rs5c313_read_data();
}

static void rs5c313_write_reg(unsigned char addr, unsigned char data)
{
        data &= 0x0f;
        rs5c313_write_data(addr | RS5C313_CNTBIT_AD);
        rs5c313_write_data(data | RS5C313_CNTBIT_DT);
        return;
}

static inline unsigned char rs5c313_read_cntreg(void)
{
        return rs5c313_read_reg(RS5C313_ADDR_CNTREG);
}

static inline void rs5c313_write_cntreg(unsigned char data)
{
        rs5c313_write_reg(RS5C313_ADDR_CNTREG, data);
}

static inline void rs5c313_write_intintvreg(unsigned char data)
{
        rs5c313_write_reg(RS5C313_ADDR_INTINTVREG, data);
}

static int rs5c313_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        int data;
        int cnt;

        cnt = 0;
        while (1) {
                RS5C313_CEENABLE;       /* CE:H */

                /* Initialize control reg. 24 hour */
                rs5c313_write_cntreg(0x04);

                if (!(rs5c313_read_cntreg() & RS5C313_CNTREG_ADJ_BSY))
                        break;

                RS5C313_CEDISABLE;
                ndelay(700);    /* CE:L */

                if (cnt++ > 100) {
                        dev_err(dev, "%s: timeout error\n", __func__);
                        return -EIO;
                }
        }

        data = rs5c313_read_reg(RS5C313_ADDR_SEC);
        data |= (rs5c313_read_reg(RS5C313_ADDR_SEC10) << 4);
        tm->tm_sec = bcd2bin(data);

        data = rs5c313_read_reg(RS5C313_ADDR_MIN);
        data |= (rs5c313_read_reg(RS5C313_ADDR_MIN10) << 4);
        tm->tm_min = bcd2bin(data);

        data = rs5c313_read_reg(RS5C313_ADDR_HOUR);
        data |= (rs5c313_read_reg(RS5C313_ADDR_HOUR10) << 4);
        tm->tm_hour = bcd2bin(data);

        data = rs5c313_read_reg(RS5C313_ADDR_DAY);
        data |= (rs5c313_read_reg(RS5C313_ADDR_DAY10) << 4);
        tm->tm_mday = bcd2bin(data);

        data = rs5c313_read_reg(RS5C313_ADDR_MON);
        data |= (rs5c313_read_reg(RS5C313_ADDR_MON10) << 4);
        tm->tm_mon = bcd2bin(data) - 1;

        data = rs5c313_read_reg(RS5C313_ADDR_YEAR);
        data |= (rs5c313_read_reg(RS5C313_ADDR_YEAR10) << 4);
        tm->tm_year = bcd2bin(data);

        if (tm->tm_year < 70)
                tm->tm_year += 100;

        data = rs5c313_read_reg(RS5C313_ADDR_WEEK);
        tm->tm_wday = bcd2bin(data);

        RS5C313_CEDISABLE;
        ndelay(700);            /* CE:L */

        return 0;
}

static int rs5c313_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        int data;
        int cnt;

        cnt = 0;
        /* busy check. */
        while (1) {
                RS5C313_CEENABLE;       /* CE:H */

                /* Initialize control reg. 24 hour */
                rs5c313_write_cntreg(0x04);

                if (!(rs5c313_read_cntreg() & RS5C313_CNTREG_ADJ_BSY))
                        break;
                RS5C313_MISCOP;
                RS5C313_CEDISABLE;
                ndelay(700);    /* CE:L */

                if (cnt++ > 100) {
                        dev_err(dev, "%s: timeout error\n", __func__);
                        return -EIO;
                }
        }

        data = bin2bcd(tm->tm_sec);
        rs5c313_write_reg(RS5C313_ADDR_SEC, data);
        rs5c313_write_reg(RS5C313_ADDR_SEC10, (data >> 4));

        data = bin2bcd(tm->tm_min);
        rs5c313_write_reg(RS5C313_ADDR_MIN, data);
        rs5c313_write_reg(RS5C313_ADDR_MIN10, (data >> 4));

        data = bin2bcd(tm->tm_hour);
        rs5c313_write_reg(RS5C313_ADDR_HOUR, data);
        rs5c313_write_reg(RS5C313_ADDR_HOUR10, (data >> 4));

        data = bin2bcd(tm->tm_mday);
        rs5c313_write_reg(RS5C313_ADDR_DAY, data);
        rs5c313_write_reg(RS5C313_ADDR_DAY10, (data >> 4));

        data = bin2bcd(tm->tm_mon + 1);
        rs5c313_write_reg(RS5C313_ADDR_MON, data);
        rs5c313_write_reg(RS5C313_ADDR_MON10, (data >> 4));

        data = bin2bcd(tm->tm_year % 100);
        rs5c313_write_reg(RS5C313_ADDR_YEAR, data);
        rs5c313_write_reg(RS5C313_ADDR_YEAR10, (data >> 4));

        data = bin2bcd(tm->tm_wday);
        rs5c313_write_reg(RS5C313_ADDR_WEEK, data);

        RS5C313_CEDISABLE;      /* CE:H */
        ndelay(700);

        return 0;
}

static void rs5c313_check_xstp_bit(void)
{
        struct rtc_time tm;
        int cnt;

        RS5C313_CEENABLE;       /* CE:H */
        if (rs5c313_read_cntreg() & RS5C313_CNTREG_WTEN_XSTP) {
                /* INT interval reg. OFF */
                rs5c313_write_intintvreg(0x00);
                /* Initialize control reg. 24 hour & adjust */
                rs5c313_write_cntreg(0x07);

                /* busy check. */
                for (cnt = 0; cnt < 100; cnt++) {
                        if (!(rs5c313_read_cntreg() & RS5C313_CNTREG_ADJ_BSY))
                                break;
                        RS5C313_MISCOP;
                }

                memset(&tm, 0, sizeof(struct rtc_time));
                tm.tm_mday      = 1;
                tm.tm_mon       = 1 - 1;
                tm.tm_year      = 2000 - 1900;

                rs5c313_rtc_set_time(NULL, &tm);
                pr_err("invalid value, resetting to 1 Jan 2000\n");
        }
        RS5C313_CEDISABLE;
        ndelay(700);            /* CE:L */
}

static const struct rtc_class_ops rs5c313_rtc_ops = {
        .read_time = rs5c313_rtc_read_time,
        .set_time = rs5c313_rtc_set_time,
};

static int rs5c313_rtc_probe(struct platform_device *pdev)
{
        struct rtc_device *rtc;

        rs5c313_init_port();
        rs5c313_check_xstp_bit();

        rtc = devm_rtc_device_register(&pdev->dev, "rs5c313", &rs5c313_rtc_ops,
                                       THIS_MODULE);

        return PTR_ERR_OR_ZERO(rtc);
}

static struct platform_driver rs5c313_rtc_platform_driver = {
        .driver         = {
                .name   = DRV_NAME,
        },
        .probe  = rs5c313_rtc_probe,
};

module_platform_driver(rs5c313_rtc_platform_driver);

MODULE_AUTHOR("kogiidena , Nobuhiro Iwamatsu <iwamatsu@nigauri.org>");
MODULE_DESCRIPTION("Ricoh RS5C313 RTC device driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRV_NAME);