rtc-twl.c

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/*
 * rtc-twl.c -- TWL Real Time Clock interface
 *
 * Copyright (C) 2007 MontaVista Software, Inc
 * Author: Alexandre Rusev <[email protected]>
 *
 * 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 <[email protected]> or <[email protected]>
 *   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/twl.h>


/*
 * RTC block register offsets (use TWL_MODULE_RTC)
 */
enum {
    REG_SECONDS_REG = 0,
    REG_MINUTES_REG,
    REG_HOURS_REG,
    REG_DAYS_REG,
    REG_MONTHS_REG,
    REG_YEARS_REG,
    REG_WEEKS_REG,

    REG_ALARM_SECONDS_REG,
    REG_ALARM_MINUTES_REG,
    REG_ALARM_HOURS_REG,
    REG_ALARM_DAYS_REG,
    REG_ALARM_MONTHS_REG,
    REG_ALARM_YEARS_REG,

    REG_RTC_CTRL_REG,
    REG_RTC_STATUS_REG,
    REG_RTC_INTERRUPTS_REG,

    REG_RTC_COMP_LSB_REG,
    REG_RTC_COMP_MSB_REG,
};
static const u8 twl4030_rtc_reg_map[] = {
    [REG_SECONDS_REG] = 0x00,
    [REG_MINUTES_REG] = 0x01,
    [REG_HOURS_REG] = 0x02,
    [REG_DAYS_REG] = 0x03,
    [REG_MONTHS_REG] = 0x04,
    [REG_YEARS_REG] = 0x05,
    [REG_WEEKS_REG] = 0x06,

    [REG_ALARM_SECONDS_REG] = 0x07,
    [REG_ALARM_MINUTES_REG] = 0x08,
    [REG_ALARM_HOURS_REG] = 0x09,
    [REG_ALARM_DAYS_REG] = 0x0A,
    [REG_ALARM_MONTHS_REG] = 0x0B,
    [REG_ALARM_YEARS_REG] = 0x0C,

    [REG_RTC_CTRL_REG] = 0x0D,
    [REG_RTC_STATUS_REG] = 0x0E,
    [REG_RTC_INTERRUPTS_REG] = 0x0F,

    [REG_RTC_COMP_LSB_REG] = 0x10,
    [REG_RTC_COMP_MSB_REG] = 0x11,
};
static const u8 twl6030_rtc_reg_map[] = {
    [REG_SECONDS_REG] = 0x00,
    [REG_MINUTES_REG] = 0x01,
    [REG_HOURS_REG] = 0x02,
    [REG_DAYS_REG] = 0x03,
    [REG_MONTHS_REG] = 0x04,
    [REG_YEARS_REG] = 0x05,
    [REG_WEEKS_REG] = 0x06,

    [REG_ALARM_SECONDS_REG] = 0x08,
    [REG_ALARM_MINUTES_REG] = 0x09,
    [REG_ALARM_HOURS_REG] = 0x0A,
    [REG_ALARM_DAYS_REG] = 0x0B,
    [REG_ALARM_MONTHS_REG] = 0x0C,
    [REG_ALARM_YEARS_REG] = 0x0D,

    [REG_RTC_CTRL_REG] = 0x10,
    [REG_RTC_STATUS_REG] = 0x11,
    [REG_RTC_INTERRUPTS_REG] = 0x12,

    [REG_RTC_COMP_LSB_REG] = 0x13,
    [REG_RTC_COMP_MSB_REG] = 0x14,
};

/* 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
#define BIT_RTC_CTRL_REG_RTC_V_OPT               0x80

/* 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

/*----------------------------------------------------------------------*/
static u8  *rtc_reg_map;

/*
 * Supports 1 byte read from TWL RTC register.
 */
static int twl_rtc_read_u8(u8 *data, u8 reg)
{
    int ret;

    ret = twl_i2c_read_u8(TWL_MODULE_RTC, data, (rtc_reg_map[reg]));
    if (ret < 0)
        pr_err("twl_rtc: Could not read TWL"
               "register %X - error %d\n", reg, ret);
    return ret;
}

/*
 * Supports 1 byte write to TWL RTC registers.
 */
static int twl_rtc_write_u8(u8 data, u8 reg)
{
    int ret;

    ret = twl_i2c_write_u8(TWL_MODULE_RTC, data, (rtc_reg_map[reg]));
    if (ret < 0)
        pr_err("twl_rtc: Could not write TWL"
               "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;

    /* if the bit is set, return from here */
    if (rtc_irq_bits & bit)
        return 0;

    val = rtc_irq_bits | bit;
    val &= ~BIT_RTC_INTERRUPTS_REG_EVERY_M;
    ret = twl_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;

    /* if the bit is clear, return from here */
    if (!(rtc_irq_bits & bit))
        return 0;

    val = rtc_irq_bits & ~bit;
    ret = twl_rtc_write_u8(val, REG_RTC_INTERRUPTS_REG);
    if (ret == 0)
        rtc_irq_bits = val;

    return ret;
}

static int twl_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;
}

/*
 * Gets current TWL 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 twl_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
    unsigned char rtc_data[ALL_TIME_REGS + 1];
    int ret;
    u8 save_control;
    u8 rtc_control;

    ret = twl_rtc_read_u8(&save_control, REG_RTC_CTRL_REG);
    if (ret < 0) {
        dev_err(dev, "%s: reading CTRL_REG, error %d\n", __func__, ret);
        return ret;
    }
    /* for twl6030/32 make sure BIT_RTC_CTRL_REG_GET_TIME_M is clear */
    if (twl_class_is_6030()) {
        if (save_control & BIT_RTC_CTRL_REG_GET_TIME_M) {
            save_control &= ~BIT_RTC_CTRL_REG_GET_TIME_M;
            ret = twl_rtc_write_u8(save_control, REG_RTC_CTRL_REG);
            if (ret < 0) {
                dev_err(dev, "%s clr GET_TIME, error %d\n",
                    __func__, ret);
                return ret;
            }
        }
    }

    /* Copy RTC counting registers to static registers or latches */
    rtc_control = save_control | BIT_RTC_CTRL_REG_GET_TIME_M;

    /* for twl6030/32 enable read access to static shadowed registers */
    if (twl_class_is_6030())
        rtc_control |= BIT_RTC_CTRL_REG_RTC_V_OPT;

    ret = twl_rtc_write_u8(rtc_control, REG_RTC_CTRL_REG);
    if (ret < 0) {
        dev_err(dev, "%s: writing CTRL_REG, error %d\n", __func__, ret);
        return ret;
    }

    ret = twl_i2c_read(TWL_MODULE_RTC, rtc_data,
            (rtc_reg_map[REG_SECONDS_REG]), ALL_TIME_REGS);

    if (ret < 0) {
        dev_err(dev, "%s: reading data, error %d\n", __func__, ret);
        return ret;
    }

    /* for twl6030 restore original state of rtc control register */
    if (twl_class_is_6030()) {
        ret = twl_rtc_write_u8(save_control, REG_RTC_CTRL_REG);
        if (ret < 0) {
            dev_err(dev, "%s: restore CTRL_REG, error %d\n",
                __func__, 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 twl_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 = twl_rtc_read_u8(&save_control, REG_RTC_CTRL_REG);
    if (ret < 0)
        goto out;

    save_control &= ~BIT_RTC_CTRL_REG_STOP_RTC_M;
    ret = twl_rtc_write_u8(save_control, REG_RTC_CTRL_REG);
    if (ret < 0)
        goto out;

    /* update all the time registers in one shot */
    ret = twl_i2c_write(TWL_MODULE_RTC, rtc_data,
        (rtc_reg_map[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 = twl_rtc_write_u8(save_control, REG_RTC_CTRL_REG);

out:
    return ret;
}

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

    ret = twl_i2c_read(TWL_MODULE_RTC, rtc_data,
            (rtc_reg_map[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 twl_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
    unsigned char alarm_data[ALL_TIME_REGS + 1];
    int ret;

    ret = twl_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 = twl_i2c_write(TWL_MODULE_RTC, alarm_data,
        (rtc_reg_map[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 = twl_rtc_alarm_irq_enable(dev, 1);
out:
    return ret;
}

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

    res = twl_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_PF;

    res = twl_rtc_write_u8(BIT_RTC_STATUS_REG_ALARM_M,
                   REG_RTC_STATUS_REG);
    if (res)
        goto out;

    if (twl_class_is_4030()) {
        /* 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_twl_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 = twl_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 twl_rtc_ops = {
    .read_time  = twl_rtc_read_time,
    .set_time   = twl_rtc_set_time,
    .read_alarm = twl_rtc_read_alarm,
    .set_alarm  = twl_rtc_set_alarm,
    .alarm_irq_enable = twl_rtc_alarm_irq_enable,
};

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

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

    if (irq <= 0)
        goto out1;

    ret = twl_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 = twl_rtc_write_u8(rd_reg, REG_RTC_STATUS_REG);
    if (ret < 0)
        goto out1;

    if (twl_class_is_6030()) {
        twl6030_interrupt_unmask(TWL6030_RTC_INT_MASK,
            REG_INT_MSK_LINE_A);
        twl6030_interrupt_unmask(TWL6030_RTC_INT_MASK,
            REG_INT_MSK_STS_A);
    }

    dev_info(&pdev->dev, "Enabling TWL-RTC\n");
    ret = twl_rtc_write_u8(BIT_RTC_CTRL_REG_STOP_RTC_M, REG_RTC_CTRL_REG);
    if (ret < 0)
        goto out1;

    /* ensure interrupts are disabled, bootloaders can be strange */
    ret = twl_rtc_write_u8(0, REG_RTC_INTERRUPTS_REG);
    if (ret < 0)
        dev_warn(&pdev->dev, "unable to disable interrupt\n");

    /* init cached IRQ enable bits */
    ret = twl_rtc_read_u8(&rtc_irq_bits, REG_RTC_INTERRUPTS_REG);
    if (ret < 0)
        goto out1;

    rtc = rtc_device_register(pdev->name,
                  &pdev->dev, &twl_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 out1;
    }

    ret = request_threaded_irq(irq, NULL, twl_rtc_interrupt,
                   IRQF_TRIGGER_RISING | IRQF_ONESHOT,
                   dev_name(&rtc->dev), rtc);
    if (ret < 0) {
        dev_err(&pdev->dev, "IRQ is not free.\n");
        goto out2;
    }

    platform_set_drvdata(pdev, rtc);
    return 0;

out2:
    rtc_device_unregister(rtc);
out1:
    return ret;
}

/*
 * Disable all TWL RTC module interrupts.
 * Sets status flag to free.
 */
static int __devexit twl_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);
    if (twl_class_is_6030()) {
        twl6030_interrupt_mask(TWL6030_RTC_INT_MASK,
            REG_INT_MSK_LINE_A);
        twl6030_interrupt_mask(TWL6030_RTC_INT_MASK,
            REG_INT_MSK_STS_A);
    }


    free_irq(irq, rtc);

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

static void twl_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 twl_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 twl_rtc_resume(struct platform_device *pdev)
{
    set_rtc_irq_bit(irqstat);
    return 0;
}

#else
#define twl_rtc_suspend NULL
#define twl_rtc_resume  NULL
#endif

static const struct of_device_id twl_rtc_of_match[] = {
    {.compatible = "ti,twl4030-rtc", },
    { },
};
MODULE_DEVICE_TABLE(of, twl_rtc_of_match);
MODULE_ALIAS("platform:twl_rtc");

static struct platform_driver twl4030rtc_driver = {
    .probe      = twl_rtc_probe,
    .remove     = __devexit_p(twl_rtc_remove),
    .shutdown   = twl_rtc_shutdown,
    .suspend    = twl_rtc_suspend,
    .resume     = twl_rtc_resume,
    .driver     = {
        .owner      = THIS_MODULE,
        .name       = "twl_rtc",
        .of_match_table = twl_rtc_of_match,
    },
};

static int __init twl_rtc_init(void)
{
    if (twl_class_is_4030())
        rtc_reg_map = (u8 *) twl4030_rtc_reg_map;
    else
        rtc_reg_map = (u8 *) twl6030_rtc_reg_map;

    return platform_driver_register(&twl4030rtc_driver);
}
module_init(twl_rtc_init);

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

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