/*
 *  Faraday Technology FTRTC010 driver
 *
 *  Copyright (C) 2009 Janos Laube <janos.dev@gmail.com>
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * Original code for older kernel 2.6.15 are from Stormlinksemi
 * first update from Janos Laube for > 2.6.29 kernels
 *
 * checkpatch fixes and usage of rtc-lib code
 * Hans Ulli Kroll <ulli.kroll@googlemail.com>
 */

#include <linux/rtc.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/clk.h>

#define DRV_NAME        "rtc-ftrtc010"

MODULE_AUTHOR("Hans Ulli Kroll <ulli.kroll@googlemail.com>");
MODULE_DESCRIPTION("RTC driver for Gemini SoC");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRV_NAME);

struct ftrtc010_rtc {
        struct rtc_device       *rtc_dev;
        void __iomem            *rtc_base;
        int                     rtc_irq;
        struct clk              *pclk;
        struct clk              *extclk;
};

enum ftrtc010_rtc_offsets {
        FTRTC010_RTC_SECOND             = 0x00,
        FTRTC010_RTC_MINUTE             = 0x04,
        FTRTC010_RTC_HOUR               = 0x08,
        FTRTC010_RTC_DAYS               = 0x0C,
        FTRTC010_RTC_ALARM_SECOND       = 0x10,
        FTRTC010_RTC_ALARM_MINUTE       = 0x14,
        FTRTC010_RTC_ALARM_HOUR         = 0x18,
        FTRTC010_RTC_RECORD             = 0x1C,
        FTRTC010_RTC_CR                 = 0x20,
};

static irqreturn_t ftrtc010_rtc_interrupt(int irq, void *dev)
{
        return IRQ_HANDLED;
}

/*
 * Looks like the RTC in the Gemini SoC is (totaly) broken
 * We can't read/write directly the time from RTC registers.
 * We must do some "offset" calculation to get the real time
 *
 * This FIX works pretty fine and Stormlinksemi aka Cortina-Networks does
 * the same thing, without the rtc-lib.c calls.
 */

static int ftrtc010_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct ftrtc010_rtc *rtc = dev_get_drvdata(dev);

        u32 days, hour, min, sec, offset;
        timeu64_t time;

        sec  = readl(rtc->rtc_base + FTRTC010_RTC_SECOND);
        min  = readl(rtc->rtc_base + FTRTC010_RTC_MINUTE);
        hour = readl(rtc->rtc_base + FTRTC010_RTC_HOUR);
        days = readl(rtc->rtc_base + FTRTC010_RTC_DAYS);
        offset = readl(rtc->rtc_base + FTRTC010_RTC_RECORD);

        time = offset + days * 86400 + hour * 3600 + min * 60 + sec;

        rtc_time64_to_tm(time, tm);

        return 0;
}

static int ftrtc010_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct ftrtc010_rtc *rtc = dev_get_drvdata(dev);
        u32 sec, min, hour, day, offset;
        timeu64_t time;

        time = rtc_tm_to_time64(tm);

        sec = readl(rtc->rtc_base + FTRTC010_RTC_SECOND);
        min = readl(rtc->rtc_base + FTRTC010_RTC_MINUTE);
        hour = readl(rtc->rtc_base + FTRTC010_RTC_HOUR);
        day = readl(rtc->rtc_base + FTRTC010_RTC_DAYS);

        offset = time - (day * 86400 + hour * 3600 + min * 60 + sec);

        writel(offset, rtc->rtc_base + FTRTC010_RTC_RECORD);
        writel(0x01, rtc->rtc_base + FTRTC010_RTC_CR);

        return 0;
}

static const struct rtc_class_ops ftrtc010_rtc_ops = {
        .read_time     = ftrtc010_rtc_read_time,
        .set_time      = ftrtc010_rtc_set_time,
};

static int ftrtc010_rtc_probe(struct platform_device *pdev)
{
        u32 days, hour, min, sec;
        struct ftrtc010_rtc *rtc;
        struct device *dev = &pdev->dev;
        struct resource *res;
        int ret;

        rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
        if (unlikely(!rtc))
                return -ENOMEM;
        platform_set_drvdata(pdev, rtc);

        rtc->pclk = devm_clk_get(dev, "PCLK");
        if (IS_ERR(rtc->pclk)) {
                dev_err(dev, "could not get PCLK\n");
        } else {
                ret = clk_prepare_enable(rtc->pclk);
                if (ret) {
                        dev_err(dev, "failed to enable PCLK\n");
                        return ret;
                }
        }
        rtc->extclk = devm_clk_get(dev, "EXTCLK");
        if (IS_ERR(rtc->extclk)) {
                dev_err(dev, "could not get EXTCLK\n");
        } else {
                ret = clk_prepare_enable(rtc->extclk);
                if (ret) {
                        dev_err(dev, "failed to enable EXTCLK\n");
                        return ret;
                }
        }

        res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
        if (!res)
                return -ENODEV;

        rtc->rtc_irq = res->start;

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

        rtc->rtc_base = devm_ioremap(dev, res->start,
                                     resource_size(res));
        if (!rtc->rtc_base)
                return -ENOMEM;

        rtc->rtc_dev = devm_rtc_allocate_device(dev);
        if (IS_ERR(rtc->rtc_dev))
                return PTR_ERR(rtc->rtc_dev);

        rtc->rtc_dev->ops = &ftrtc010_rtc_ops;

        sec  = readl(rtc->rtc_base + FTRTC010_RTC_SECOND);
        min  = readl(rtc->rtc_base + FTRTC010_RTC_MINUTE);
        hour = readl(rtc->rtc_base + FTRTC010_RTC_HOUR);
        days = readl(rtc->rtc_base + FTRTC010_RTC_DAYS);

        rtc->rtc_dev->range_min = (u64)days * 86400 + hour * 3600 +
                                  min * 60 + sec;
        rtc->rtc_dev->range_max = U32_MAX + rtc->rtc_dev->range_min;

        ret = devm_request_irq(dev, rtc->rtc_irq, ftrtc010_rtc_interrupt,
                               IRQF_SHARED, pdev->name, dev);
        if (unlikely(ret))
                return ret;

        return rtc_register_device(rtc->rtc_dev);
}

static int ftrtc010_rtc_remove(struct platform_device *pdev)
{
        struct ftrtc010_rtc *rtc = platform_get_drvdata(pdev);

        if (!IS_ERR(rtc->extclk))
                clk_disable_unprepare(rtc->extclk);
        if (!IS_ERR(rtc->pclk))
                clk_disable_unprepare(rtc->pclk);

        return 0;
}

static const struct of_device_id ftrtc010_rtc_dt_match[] = {
        { .compatible = "cortina,gemini-rtc" },
        { .compatible = "faraday,ftrtc010" },
        { }
};
MODULE_DEVICE_TABLE(of, ftrtc010_rtc_dt_match);

static struct platform_driver ftrtc010_rtc_driver = {
        .driver         = {
                .name   = DRV_NAME,
                .of_match_table = ftrtc010_rtc_dt_match,
        },
        .probe          = ftrtc010_rtc_probe,
        .remove         = ftrtc010_rtc_remove,
};

module_platform_driver_probe(ftrtc010_rtc_driver, ftrtc010_rtc_probe);