rtc-coh901331.c

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/*
 * Copyright (C) 2007-2009 ST-Ericsson AB
 * License terms: GNU General Public License (GPL) version 2
 * Real Time Clock interface for ST-Ericsson AB COH 901 331 RTC.
 * Author: Linus Walleij <[email protected]>
 * Based on rtc-pl031.c by Deepak Saxena <[email protected]>
 * Copyright 2006 (c) MontaVista Software, Inc.
 */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/clk.h>
#include <linux/interrupt.h>
#include <linux/pm.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/slab.h>

/*
 * Registers in the COH 901 331
 */
/* Alarm value 32bit (R/W) */
#define COH901331_ALARM     0x00U
/* Used to set current time 32bit (R/W) */
#define COH901331_SET_TIME  0x04U
/* Indication if current time is valid 32bit (R/-) */
#define COH901331_VALID     0x08U
/* Read the current time 32bit (R/-) */
#define COH901331_CUR_TIME  0x0cU
/* Event register for the "alarm" interrupt */
#define COH901331_IRQ_EVENT 0x10U
/* Mask register for the "alarm" interrupt */
#define COH901331_IRQ_MASK  0x14U
/* Force register for the "alarm" interrupt */
#define COH901331_IRQ_FORCE 0x18U

/*
 * Reference to RTC block clock
 * Notice that the frequent clk_enable()/clk_disable() on this
 * clock is mainly to be able to turn on/off other clocks in the
 * hierarchy as needed, the RTC clock is always on anyway.
 */
struct coh901331_port {
    struct rtc_device *rtc;
    struct clk *clk;
    u32 phybase;
    u32 physize;
    void __iomem *virtbase;
    int irq;
#ifdef CONFIG_PM
    u32 irqmaskstore;
#endif
};

static irqreturn_t coh901331_interrupt(int irq, void *data)
{
    struct coh901331_port *rtap = data;

    clk_enable(rtap->clk);
    /* Ack IRQ */
    writel(1, rtap->virtbase + COH901331_IRQ_EVENT);
    /*
     * Disable the interrupt. This is necessary because
     * the RTC lives on a lower-clocked line and will
     * not release the IRQ line until after a few (slower)
     * clock cycles. The interrupt will be re-enabled when
     * a new alarm is set anyway.
     */
    writel(0, rtap->virtbase + COH901331_IRQ_MASK);
    clk_disable(rtap->clk);

    /* Set alarm flag */
    rtc_update_irq(rtap->rtc, 1, RTC_AF);

    return IRQ_HANDLED;
}

static int coh901331_read_time(struct device *dev, struct rtc_time *tm)
{
    struct coh901331_port *rtap = dev_get_drvdata(dev);

    clk_enable(rtap->clk);
    /* Check if the time is valid */
    if (readl(rtap->virtbase + COH901331_VALID)) {
        rtc_time_to_tm(readl(rtap->virtbase + COH901331_CUR_TIME), tm);
        clk_disable(rtap->clk);
        return rtc_valid_tm(tm);
    }
    clk_disable(rtap->clk);
    return -EINVAL;
}

static int coh901331_set_mmss(struct device *dev, unsigned long secs)
{
    struct coh901331_port *rtap = dev_get_drvdata(dev);

    clk_enable(rtap->clk);
    writel(secs, rtap->virtbase + COH901331_SET_TIME);
    clk_disable(rtap->clk);

    return 0;
}

static int coh901331_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
    struct coh901331_port *rtap = dev_get_drvdata(dev);

    clk_enable(rtap->clk);
    rtc_time_to_tm(readl(rtap->virtbase + COH901331_ALARM), &alarm->time);
    alarm->pending = readl(rtap->virtbase + COH901331_IRQ_EVENT) & 1U;
    alarm->enabled = readl(rtap->virtbase + COH901331_IRQ_MASK) & 1U;
    clk_disable(rtap->clk);

    return 0;
}

static int coh901331_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
    struct coh901331_port *rtap = dev_get_drvdata(dev);
    unsigned long time;

    rtc_tm_to_time(&alarm->time, &time);
    clk_enable(rtap->clk);
    writel(time, rtap->virtbase + COH901331_ALARM);
    writel(alarm->enabled, rtap->virtbase + COH901331_IRQ_MASK);
    clk_disable(rtap->clk);

    return 0;
}

static int coh901331_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
    struct coh901331_port *rtap = dev_get_drvdata(dev);

    clk_enable(rtap->clk);
    if (enabled)
        writel(1, rtap->virtbase + COH901331_IRQ_MASK);
    else
        writel(0, rtap->virtbase + COH901331_IRQ_MASK);
    clk_disable(rtap->clk);

    return 0;
}

static struct rtc_class_ops coh901331_ops = {
    .read_time = coh901331_read_time,
    .set_mmss = coh901331_set_mmss,
    .read_alarm = coh901331_read_alarm,
    .set_alarm = coh901331_set_alarm,
    .alarm_irq_enable = coh901331_alarm_irq_enable,
};

static int __exit coh901331_remove(struct platform_device *pdev)
{
    struct coh901331_port *rtap = dev_get_drvdata(&pdev->dev);

    if (rtap) {
        rtc_device_unregister(rtap->rtc);
        clk_unprepare(rtap->clk);
        clk_put(rtap->clk);
        platform_set_drvdata(pdev, NULL);
    }

    return 0;
}


static int __init coh901331_probe(struct platform_device *pdev)
{
    int ret;
    struct coh901331_port *rtap;
    struct resource *res;

    rtap = devm_kzalloc(&pdev->dev,
                sizeof(struct coh901331_port), GFP_KERNEL);
    if (!rtap)
        return -ENOMEM;

    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (!res)
        return -ENOENT;

    rtap->phybase = res->start;
    rtap->physize = resource_size(res);

    if (devm_request_mem_region(&pdev->dev, rtap->phybase, rtap->physize,
                    "rtc-coh901331") == NULL)
        return -EBUSY;

    rtap->virtbase = devm_ioremap(&pdev->dev, rtap->phybase, rtap->physize);
    if (!rtap->virtbase)
        return -ENOMEM;

    rtap->irq = platform_get_irq(pdev, 0);
    if (devm_request_irq(&pdev->dev, rtap->irq, coh901331_interrupt, 0,
                 "RTC COH 901 331 Alarm", rtap))
        return -EIO;

    rtap->clk = clk_get(&pdev->dev, NULL);
    if (IS_ERR(rtap->clk)) {
        ret = PTR_ERR(rtap->clk);
        dev_err(&pdev->dev, "could not get clock\n");
        return ret;
    }

    /* We enable/disable the clock only to assure it works */
    ret = clk_prepare_enable(rtap->clk);
    if (ret) {
        dev_err(&pdev->dev, "could not enable clock\n");
        goto out_no_clk_prepenable;
    }
    clk_disable(rtap->clk);

    platform_set_drvdata(pdev, rtap);
    rtap->rtc = rtc_device_register("coh901331", &pdev->dev, &coh901331_ops,
                     THIS_MODULE);
    if (IS_ERR(rtap->rtc)) {
        ret = PTR_ERR(rtap->rtc);
        goto out_no_rtc;
    }

    return 0;

 out_no_rtc:
    platform_set_drvdata(pdev, NULL);
    clk_unprepare(rtap->clk);
 out_no_clk_prepenable:
    clk_put(rtap->clk);
    return ret;
}

#ifdef CONFIG_PM
static int coh901331_suspend(struct platform_device *pdev, pm_message_t state)
{
    struct coh901331_port *rtap = dev_get_drvdata(&pdev->dev);

    /*
     * If this RTC alarm will be used for waking the system up,
     * don't disable it of course. Else we just disable the alarm
     * and await suspension.
     */
    if (device_may_wakeup(&pdev->dev)) {
        enable_irq_wake(rtap->irq);
    } else {
        clk_enable(rtap->clk);
        rtap->irqmaskstore = readl(rtap->virtbase + COH901331_IRQ_MASK);
        writel(0, rtap->virtbase + COH901331_IRQ_MASK);
        clk_disable(rtap->clk);
    }
    clk_unprepare(rtap->clk);
    return 0;
}

static int coh901331_resume(struct platform_device *pdev)
{
    struct coh901331_port *rtap = dev_get_drvdata(&pdev->dev);

    clk_prepare(rtap->clk);
    if (device_may_wakeup(&pdev->dev)) {
        disable_irq_wake(rtap->irq);
    } else {
        clk_enable(rtap->clk);
        writel(rtap->irqmaskstore, rtap->virtbase + COH901331_IRQ_MASK);
        clk_disable(rtap->clk);
    }
    return 0;
}
#else
#define coh901331_suspend NULL
#define coh901331_resume NULL
#endif

static void coh901331_shutdown(struct platform_device *pdev)
{
    struct coh901331_port *rtap = dev_get_drvdata(&pdev->dev);

    clk_enable(rtap->clk);
    writel(0, rtap->virtbase + COH901331_IRQ_MASK);
    clk_disable_unprepare(rtap->clk);
}

static struct platform_driver coh901331_driver = {
    .driver = {
        .name = "rtc-coh901331",
        .owner = THIS_MODULE,
    },
    .remove = __exit_p(coh901331_remove),
    .suspend = coh901331_suspend,
    .resume = coh901331_resume,
    .shutdown = coh901331_shutdown,
};

static int __init coh901331_init(void)
{
    return platform_driver_probe(&coh901331_driver, coh901331_probe);
}

static void __exit coh901331_exit(void)
{
    platform_driver_unregister(&coh901331_driver);
}

module_init(coh901331_init);
module_exit(coh901331_exit);

MODULE_AUTHOR("Linus Walleij <[email protected]>");
MODULE_DESCRIPTION("ST-Ericsson AB COH 901 331 RTC Driver");
MODULE_LICENSE("GPL");