rtc-sun4v.c

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/* rtc-sun4v.c: Hypervisor based RTC for SUN4V systems.
 *
 * Copyright (C) 2008 David S. Miller <[email protected]>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>

#include <asm/hypervisor.h>

static unsigned long hypervisor_get_time(void)
{
    unsigned long ret, time;
    int retries = 10000;

retry:
    ret = sun4v_tod_get(&time);
    if (ret == HV_EOK)
        return time;
    if (ret == HV_EWOULDBLOCK) {
        if (--retries > 0) {
            udelay(100);
            goto retry;
        }
        printk(KERN_WARNING "SUN4V: tod_get() timed out.\n");
        return 0;
    }
    printk(KERN_WARNING "SUN4V: tod_get() not supported.\n");
    return 0;
}

static int sun4v_read_time(struct device *dev, struct rtc_time *tm)
{
    rtc_time_to_tm(hypervisor_get_time(), tm);
    return 0;
}

static int hypervisor_set_time(unsigned long secs)
{
    unsigned long ret;
    int retries = 10000;

retry:
    ret = sun4v_tod_set(secs);
    if (ret == HV_EOK)
        return 0;
    if (ret == HV_EWOULDBLOCK) {
        if (--retries > 0) {
            udelay(100);
            goto retry;
        }
        printk(KERN_WARNING "SUN4V: tod_set() timed out.\n");
        return -EAGAIN;
    }
    printk(KERN_WARNING "SUN4V: tod_set() not supported.\n");
    return -EOPNOTSUPP;
}

static int sun4v_set_time(struct device *dev, struct rtc_time *tm)
{
    unsigned long secs;
    int err;

    err = rtc_tm_to_time(tm, &secs);
    if (err)
        return err;

    return hypervisor_set_time(secs);
}

static const struct rtc_class_ops sun4v_rtc_ops = {
    .read_time  = sun4v_read_time,
    .set_time   = sun4v_set_time,
};

static int __init sun4v_rtc_probe(struct platform_device *pdev)
{
    struct rtc_device *rtc = rtc_device_register("sun4v", &pdev->dev,
                     &sun4v_rtc_ops, THIS_MODULE);
    if (IS_ERR(rtc))
        return PTR_ERR(rtc);

    platform_set_drvdata(pdev, rtc);
    return 0;
}

static int __exit sun4v_rtc_remove(struct platform_device *pdev)
{
    struct rtc_device *rtc = platform_get_drvdata(pdev);

    rtc_device_unregister(rtc);
    return 0;
}

static struct platform_driver sun4v_rtc_driver = {
    .driver     = {
        .name   = "rtc-sun4v",
        .owner  = THIS_MODULE,
    },
    .remove     = __exit_p(sun4v_rtc_remove),
};

static int __init sun4v_rtc_init(void)
{
    return platform_driver_probe(&sun4v_rtc_driver, sun4v_rtc_probe);
}

static void __exit sun4v_rtc_exit(void)
{
    platform_driver_unregister(&sun4v_rtc_driver);
}

module_init(sun4v_rtc_init);
module_exit(sun4v_rtc_exit);

MODULE_AUTHOR("David S. Miller <[email protected]>");
MODULE_DESCRIPTION("SUN4V RTC driver");
MODULE_LICENSE("GPL");