/*
 * rtc-twl4030.c -- TWL4030 Real Time Clock interface
 *
 * Copyright (C) 2007 MontaVista Software, Inc
 * Author: Alexandre Rusev <source@mvista.com>
 *
 * Based on original TI driver twl4030-rtc.c
 *   Copyright (C) 2006 Texas Instruments, Inc.
 *
 * Based on rtc-omap.c
 *   Copyright (C) 2003 MontaVista Software, Inc.
 *   Author: George G. Davis <gdavis@mvista.com> or <source@mvista.com>
 *   Copyright (C) 2006 David Brownell
 *
 * 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/errno.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>

#include <linux/i2c/twl4030.h>


/*
 * RTC block register offsets (use TWL_MODULE_RTC)
 */
#define REG_SECONDS_REG                          0x00
#define REG_MINUTES_REG                          0x01
#define REG_HOURS_REG                            0x02
#define REG_DAYS_REG                             0x03
#define REG_MONTHS_REG                           0x04
#define REG_YEARS_REG                            0x05
#define REG_WEEKS_REG                            0x06

#define REG_ALARM_SECONDS_REG                    0x07
#define REG_ALARM_MINUTES_REG                    0x08
#define REG_ALARM_HOURS_REG                      0x09
#define REG_ALARM_DAYS_REG                       0x0A
#define REG_ALARM_MONTHS_REG                     0x0B
#define REG_ALARM_YEARS_REG                      0x0C

#define REG_RTC_CTRL_REG                         0x0D
#define REG_RTC_STATUS_REG                       0x0E
#define REG_RTC_INTERRUPTS_REG                   0x0F

#define REG_RTC_COMP_LSB_REG                     0x10
#define REG_RTC_COMP_MSB_REG                     0x11

/* RTC_CTRL_REG bitfields */
#define BIT_RTC_CTRL_REG_STOP_RTC_M              0x01
#define BIT_RTC_CTRL_REG_ROUND_30S_M             0x02
#define BIT_RTC_CTRL_REG_AUTO_COMP_M             0x04
#define BIT_RTC_CTRL_REG_MODE_12_24_M            0x08
#define BIT_RTC_CTRL_REG_TEST_MODE_M             0x10
#define BIT_RTC_CTRL_REG_SET_32_COUNTER_M        0x20
#define BIT_RTC_CTRL_REG_GET_TIME_M              0x40

/* RTC_STATUS_REG bitfields */
#define BIT_RTC_STATUS_REG_RUN_M                 0x02
#define BIT_RTC_STATUS_REG_1S_EVENT_M            0x04
#define BIT_RTC_STATUS_REG_1M_EVENT_M            0x08
#define BIT_RTC_STATUS_REG_1H_EVENT_M            0x10
#define BIT_RTC_STATUS_REG_1D_EVENT_M            0x20
#define BIT_RTC_STATUS_REG_ALARM_M               0x40
#define BIT_RTC_STATUS_REG_POWER_UP_M            0x80

/* RTC_INTERRUPTS_REG bitfields */
#define BIT_RTC_INTERRUPTS_REG_EVERY_M           0x03
#define BIT_RTC_INTERRUPTS_REG_IT_TIMER_M        0x04
#define BIT_RTC_INTERRUPTS_REG_IT_ALARM_M        0x08


/* REG_SECONDS_REG through REG_YEARS_REG is how many registers? */
#define ALL_TIME_REGS           6

/*----------------------------------------------------------------------*/

/*
 * Supports 1 byte read from TWL4030 RTC register.
 */
static int twl4030_rtc_read_u8(u8 *data, u8 reg)
{
        int ret;

        ret = twl4030_i2c_read_u8(TWL4030_MODULE_RTC, data, reg);
        if (ret < 0)
                pr_err("twl4030_rtc: Could not read TWL4030"
                       "register %X - error %d\n", reg, ret);
        return ret;
}

/*
 * Supports 1 byte write to TWL4030 RTC registers.
 */
static int twl4030_rtc_write_u8(u8 data, u8 reg)
{
        int ret;

        ret = twl4030_i2c_write_u8(TWL4030_MODULE_RTC, data, reg);
        if (ret < 0)
                pr_err("twl4030_rtc: Could not write TWL4030"
                       "register %X - error %d\n", reg, ret);
        return ret;
}

/*
 * Cache the value for timer/alarm interrupts register; this is
 * only changed by callers holding rtc ops lock (or resume).
 */
static unsigned char rtc_irq_bits;

/*
 * Enable 1/second update and/or alarm interrupts.
 */
static int set_rtc_irq_bit(unsigned char bit)
{
        unsigned char val;
        int ret;

        val = rtc_irq_bits | bit;
        val &= ~BIT_RTC_INTERRUPTS_REG_EVERY_M;
        ret = twl4030_rtc_write_u8(val, REG_RTC_INTERRUPTS_REG);
        if (ret == 0)
                rtc_irq_bits = val;

        return ret;
}

/*
 * Disable update and/or alarm interrupts.
 */
static int mask_rtc_irq_bit(unsigned char bit)
{
        unsigned char val;
        int ret;

        val = rtc_irq_bits & ~bit;
        ret = twl4030_rtc_write_u8(val, REG_RTC_INTERRUPTS_REG);
        if (ret == 0)
                rtc_irq_bits = val;

        return ret;
}

static int twl4030_rtc_alarm_irq_enable(struct device *dev, unsigned enabled)
{
        int ret;

        if (enabled)
                ret = set_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_ALARM_M);
        else
                ret = mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_ALARM_M);

        return ret;
}

static int twl4030_rtc_update_irq_enable(struct device *dev, unsigned enabled)
{
        int ret;

        if (enabled)
                ret = set_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_TIMER_M);
        else
                ret = mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_TIMER_M);

        return ret;
}

/*
 * Gets current TWL4030 RTC time and date parameters.
 *
 * The RTC's time/alarm representation is not what gmtime(3) requires
 * Linux to use:
 *
 *  - Months are 1..12 vs Linux 0-11
 *  - Years are 0..99 vs Linux 1900..N (we assume 21st century)
 */
static int twl4030_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        unsigned char rtc_data[ALL_TIME_REGS + 1];
        int ret;
        u8 save_control;

        ret = twl4030_rtc_read_u8(&save_control, REG_RTC_CTRL_REG);
        if (ret < 0)
                return ret;

        save_control |= BIT_RTC_CTRL_REG_GET_TIME_M;

        ret = twl4030_rtc_write_u8(save_control, REG_RTC_CTRL_REG);
        if (ret < 0)
                return ret;

        ret = twl4030_i2c_read(TWL4030_MODULE_RTC, rtc_data,
                               REG_SECONDS_REG, ALL_TIME_REGS);

        if (ret < 0) {
                dev_err(dev, "rtc_read_time error %d\n", ret);
                return ret;
        }

        tm->tm_sec = bcd2bin(rtc_data[0]);
        tm->tm_min = bcd2bin(rtc_data[1]);
        tm->tm_hour = bcd2bin(rtc_data[2]);
        tm->tm_mday = bcd2bin(rtc_data[3]);
        tm->tm_mon = bcd2bin(rtc_data[4]) - 1;
        tm->tm_year = bcd2bin(rtc_data[5]) + 100;

        return ret;
}

static int twl4030_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        unsigned char save_control;
        unsigned char rtc_data[ALL_TIME_REGS + 1];
        int ret;

        rtc_data[1] = bin2bcd(tm->tm_sec);
        rtc_data[2] = bin2bcd(tm->tm_min);
        rtc_data[3] = bin2bcd(tm->tm_hour);
        rtc_data[4] = bin2bcd(tm->tm_mday);
        rtc_data[5] = bin2bcd(tm->tm_mon + 1);
        rtc_data[6] = bin2bcd(tm->tm_year - 100);

        /* Stop RTC while updating the TC registers */
        ret = twl4030_rtc_read_u8(&save_control, REG_RTC_CTRL_REG);
        if (ret < 0)
                goto out;

        save_control &= ~BIT_RTC_CTRL_REG_STOP_RTC_M;
        twl4030_rtc_write_u8(save_control, REG_RTC_CTRL_REG);
        if (ret < 0)
                goto out;

        /* update all the time registers in one shot */
        ret = twl4030_i2c_write(TWL4030_MODULE_RTC, rtc_data,
                        REG_SECONDS_REG, ALL_TIME_REGS);
        if (ret < 0) {
                dev_err(dev, "rtc_set_time error %d\n", ret);
                goto out;
        }

        /* Start back RTC */
        save_control |= BIT_RTC_CTRL_REG_STOP_RTC_M;
        ret = twl4030_rtc_write_u8(save_control, REG_RTC_CTRL_REG);

out:
        return ret;
}

/*
 * Gets current TWL4030 RTC alarm time.
 */
static int twl4030_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
        unsigned char rtc_data[ALL_TIME_REGS + 1];
        int ret;

        ret = twl4030_i2c_read(TWL4030_MODULE_RTC, rtc_data,
                               REG_ALARM_SECONDS_REG, ALL_TIME_REGS);
        if (ret < 0) {
                dev_err(dev, "rtc_read_alarm error %d\n", ret);
                return ret;
        }

        /* some of these fields may be wildcard/"match all" */
        alm->time.tm_sec = bcd2bin(rtc_data[0]);
        alm->time.tm_min = bcd2bin(rtc_data[1]);
        alm->time.tm_hour = bcd2bin(rtc_data[2]);
        alm->time.tm_mday = bcd2bin(rtc_data[3]);
        alm->time.tm_mon = bcd2bin(rtc_data[4]) - 1;
        alm->time.tm_year = bcd2bin(rtc_data[5]) + 100;

        /* report cached alarm enable state */
        if (rtc_irq_bits & BIT_RTC_INTERRUPTS_REG_IT_ALARM_M)
                alm->enabled = 1;

        return ret;
}

static int twl4030_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
        unsigned char alarm_data[ALL_TIME_REGS + 1];
        int ret;

        ret = twl4030_rtc_alarm_irq_enable(dev, 0);
        if (ret)
                goto out;

        alarm_data[1] = bin2bcd(alm->time.tm_sec);
        alarm_data[2] = bin2bcd(alm->time.tm_min);
        alarm_data[3] = bin2bcd(alm->time.tm_hour);
        alarm_data[4] = bin2bcd(alm->time.tm_mday);
        alarm_data[5] = bin2bcd(alm->time.tm_mon + 1);
        alarm_data[6] = bin2bcd(alm->time.tm_year - 100);

        /* update all the alarm registers in one shot */
        ret = twl4030_i2c_write(TWL4030_MODULE_RTC, alarm_data,
                        REG_ALARM_SECONDS_REG, ALL_TIME_REGS);
        if (ret) {
                dev_err(dev, "rtc_set_alarm error %d\n", ret);
                goto out;
        }

        if (alm->enabled)
                ret = twl4030_rtc_alarm_irq_enable(dev, 1);
out:
        return ret;
}

static irqreturn_t twl4030_rtc_interrupt(int irq, void *rtc)
{
        unsigned long events = 0;
        int ret = IRQ_NONE;
        int res;
        u8 rd_reg;

#ifdef CONFIG_LOCKDEP
        /* WORKAROUND for lockdep forcing IRQF_DISABLED on us, which
         * we don't want and can't tolerate.  Although it might be
         * friendlier not to borrow this thread context...
         */
        local_irq_enable();
#endif

        res = twl4030_rtc_read_u8(&rd_reg, REG_RTC_STATUS_REG);
        if (res)
                goto out;
        /*
         * Figure out source of interrupt: ALARM or TIMER in RTC_STATUS_REG.
         * only one (ALARM or RTC) interrupt source may be enabled
         * at time, we also could check our results
         * by reading RTS_INTERRUPTS_REGISTER[IT_TIMER,IT_ALARM]
         */
        if (rd_reg & BIT_RTC_STATUS_REG_ALARM_M)
                events |= RTC_IRQF | RTC_AF;
        else
                events |= RTC_IRQF | RTC_UF;

        res = twl4030_rtc_write_u8(rd_reg | BIT_RTC_STATUS_REG_ALARM_M,
                                   REG_RTC_STATUS_REG);
        if (res)
                goto out;

        /* Clear on Read enabled. RTC_IT bit of TWL4030_INT_PWR_ISR1
         * needs 2 reads to clear the interrupt. One read is done in
         * do_twl4030_pwrirq(). Doing the second read, to clear
         * the bit.
         *
         * FIXME the reason PWR_ISR1 needs an extra read is that
         * RTC_IF retriggered until we cleared REG_ALARM_M above.
         * But re-reading like this is a bad hack; by doing so we
         * risk wrongly clearing status for some other IRQ (losing
         * the interrupt).  Be smarter about handling RTC_UF ...
         */
        res = twl4030_i2c_read_u8(TWL4030_MODULE_INT,
                        &rd_reg, TWL4030_INT_PWR_ISR1);
        if (res)
                goto out;

        /* Notify RTC core on event */
        rtc_update_irq(rtc, 1, events);

        ret = IRQ_HANDLED;
out:
        return ret;
}

static struct rtc_class_ops twl4030_rtc_ops = {
        .read_time      = twl4030_rtc_read_time,
        .set_time       = twl4030_rtc_set_time,
        .read_alarm     = twl4030_rtc_read_alarm,
        .set_alarm      = twl4030_rtc_set_alarm,
        .alarm_irq_enable = twl4030_rtc_alarm_irq_enable,
        .update_irq_enable = twl4030_rtc_update_irq_enable,
};

/*----------------------------------------------------------------------*/

static int __devinit twl4030_rtc_probe(struct platform_device *pdev)
{
        struct rtc_device *rtc;
        int ret = 0;
        int irq = platform_get_irq(pdev, 0);
        u8 rd_reg;

        if (irq <= 0)
                return -EINVAL;

        rtc = rtc_device_register(pdev->name,
                                  &pdev->dev, &twl4030_rtc_ops, THIS_MODULE);
        if (IS_ERR(rtc)) {
                ret = PTR_ERR(rtc);
                dev_err(&pdev->dev, "can't register RTC device, err %ld\n",
                        PTR_ERR(rtc));
                goto out0;

        }

        platform_set_drvdata(pdev, rtc);

        ret = twl4030_rtc_read_u8(&rd_reg, REG_RTC_STATUS_REG);
        if (ret < 0)
                goto out1;

        if (rd_reg & BIT_RTC_STATUS_REG_POWER_UP_M)
                dev_warn(&pdev->dev, "Power up reset detected.\n");

        if (rd_reg & BIT_RTC_STATUS_REG_ALARM_M)
                dev_warn(&pdev->dev, "Pending Alarm interrupt detected.\n");

        /* Clear RTC Power up reset and pending alarm interrupts */
        ret = twl4030_rtc_write_u8(rd_reg, REG_RTC_STATUS_REG);
        if (ret < 0)
                goto out1;

        ret = request_irq(irq, twl4030_rtc_interrupt,
                                IRQF_TRIGGER_RISING,
                                dev_name(&rtc->dev), rtc);
        if (ret < 0) {
                dev_err(&pdev->dev, "IRQ is not free.\n");
                goto out1;
        }

        /* Check RTC module status, Enable if it is off */
        ret = twl4030_rtc_read_u8(&rd_reg, REG_RTC_CTRL_REG);
        if (ret < 0)
                goto out2;

        if (!(rd_reg & BIT_RTC_CTRL_REG_STOP_RTC_M)) {
                dev_info(&pdev->dev, "Enabling TWL4030-RTC.\n");
                rd_reg = BIT_RTC_CTRL_REG_STOP_RTC_M;
                ret = twl4030_rtc_write_u8(rd_reg, REG_RTC_CTRL_REG);
                if (ret < 0)
                        goto out2;
        }

        /* init cached IRQ enable bits */
        ret = twl4030_rtc_read_u8(&rtc_irq_bits, REG_RTC_INTERRUPTS_REG);
        if (ret < 0)
                goto out2;

        return ret;

out2:
        free_irq(irq, rtc);
out1:
        rtc_device_unregister(rtc);
out0:
        return ret;
}

/*
 * Disable all TWL4030 RTC module interrupts.
 * Sets status flag to free.
 */
static int __devexit twl4030_rtc_remove(struct platform_device *pdev)
{
        /* leave rtc running, but disable irqs */
        struct rtc_device *rtc = platform_get_drvdata(pdev);
        int irq = platform_get_irq(pdev, 0);

        mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_ALARM_M);
        mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_TIMER_M);

        free_irq(irq, rtc);

        rtc_device_unregister(rtc);
        platform_set_drvdata(pdev, NULL);
        return 0;
}

static void twl4030_rtc_shutdown(struct platform_device *pdev)
{
        /* mask timer interrupts, but leave alarm interrupts on to enable
           power-on when alarm is triggered */
        mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_TIMER_M);
}

#ifdef CONFIG_PM

static unsigned char irqstat;

static int twl4030_rtc_suspend(struct platform_device *pdev, pm_message_t state)
{
        irqstat = rtc_irq_bits;

        mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_TIMER_M);
        return 0;
}

static int twl4030_rtc_resume(struct platform_device *pdev)
{
        set_rtc_irq_bit(irqstat);
        return 0;
}

#else
#define twl4030_rtc_suspend NULL
#define twl4030_rtc_resume  NULL
#endif

MODULE_ALIAS("platform:twl4030_rtc");

static struct platform_driver twl4030rtc_driver = {
        .probe          = twl4030_rtc_probe,
        .remove         = __devexit_p(twl4030_rtc_remove),
        .shutdown       = twl4030_rtc_shutdown,
        .suspend        = twl4030_rtc_suspend,
        .resume         = twl4030_rtc_resume,
        .driver         = {
                .owner  = THIS_MODULE,
                .name   = "twl4030_rtc",
        },
};

static int __init twl4030_rtc_init(void)
{
        return platform_driver_register(&twl4030rtc_driver);
}
module_init(twl4030_rtc_init);

static void __exit twl4030_rtc_exit(void)
{
        platform_driver_unregister(&twl4030rtc_driver);
}
module_exit(twl4030_rtc_exit);

MODULE_AUTHOR("Texas Instruments, MontaVista Software");
MODULE_LICENSE("GPL");