LXR linux/drivers/rtc/rtc-gemini.c

   1/*
   2 *  Gemini OnChip RTC
   3 *
   4 *  Copyright (C) 2009 Janos Laube <janos.dev@gmail.com>
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation; either version 2 of the License, or
   9 * (at your option) any later version.
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * Original code for older kernel 2.6.15 are from Stormlinksemi
  17 * first update from Janos Laube for > 2.6.29 kernels
  18 *
  19 * checkpatch fixes and usage of rtc-lib code
  20 * Hans Ulli Kroll <ulli.kroll@googlemail.com>
  21 */
  22
  23#include <linux/rtc.h>
  24#include <linux/io.h>
  25#include <linux/slab.h>
  26#include <linux/platform_device.h>
  27#include <linux/kernel.h>
  28#include <linux/module.h>
  29
  30#define DRV_NAME        "rtc-gemini"
  31
  32MODULE_AUTHOR("Hans Ulli Kroll <ulli.kroll@googlemail.com>");
  33MODULE_DESCRIPTION("RTC driver for Gemini SoC");
  34MODULE_LICENSE("GPL");
  35MODULE_ALIAS("platform:" DRV_NAME);
  36
  37struct gemini_rtc {
  38        struct rtc_device       *rtc_dev;
  39        void __iomem            *rtc_base;
  40        int                     rtc_irq;
  41};
  42
  43enum gemini_rtc_offsets {
  44        GEMINI_RTC_SECOND       = 0x00,
  45        GEMINI_RTC_MINUTE       = 0x04,
  46        GEMINI_RTC_HOUR         = 0x08,
  47        GEMINI_RTC_DAYS         = 0x0C,
  48        GEMINI_RTC_ALARM_SECOND = 0x10,
  49        GEMINI_RTC_ALARM_MINUTE = 0x14,
  50        GEMINI_RTC_ALARM_HOUR   = 0x18,
  51        GEMINI_RTC_RECORD       = 0x1C,
  52        GEMINI_RTC_CR           = 0x20
  53};
  54
  55static irqreturn_t gemini_rtc_interrupt(int irq, void *dev)
  56{
  57        return IRQ_HANDLED;
  58}
  59
  60/*
  61 * Looks like the RTC in the Gemini SoC is (totaly) broken
  62 * We can't read/write directly the time from RTC registers.
  63 * We must do some "offset" calculation to get the real time
  64 *
  65 * This FIX works pretty fine and Stormlinksemi aka Cortina-Networks does
  66 * the same thing, without the rtc-lib.c calls.
  67 */
  68
  69static int gemini_rtc_read_time(struct device *dev, struct rtc_time *tm)
  70{
  71        struct gemini_rtc *rtc = dev_get_drvdata(dev);
  72
  73        unsigned int  days, hour, min, sec;
  74        unsigned long offset, time;
  75
  76        sec  = readl(rtc->rtc_base + GEMINI_RTC_SECOND);
  77        min  = readl(rtc->rtc_base + GEMINI_RTC_MINUTE);
  78        hour = readl(rtc->rtc_base + GEMINI_RTC_HOUR);
  79        days = readl(rtc->rtc_base + GEMINI_RTC_DAYS);
  80        offset = readl(rtc->rtc_base + GEMINI_RTC_RECORD);
  81
  82        time = offset + days * 86400 + hour * 3600 + min * 60 + sec;
  83
  84        rtc_time_to_tm(time, tm);
  85
  86        return 0;
  87}
  88
  89static int gemini_rtc_set_time(struct device *dev, struct rtc_time *tm)
  90{
  91        struct gemini_rtc *rtc = dev_get_drvdata(dev);
  92        unsigned int sec, min, hour, day;
  93        unsigned long offset, time;
  94
  95        if (tm->tm_year >= 2148)        /* EPOCH Year + 179 */
  96                return -EINVAL;
  97
  98        rtc_tm_to_time(tm, &time);
  99
 100        sec = readl(rtc->rtc_base + GEMINI_RTC_SECOND);
 101        min = readl(rtc->rtc_base + GEMINI_RTC_MINUTE);
 102        hour = readl(rtc->rtc_base + GEMINI_RTC_HOUR);
 103        day = readl(rtc->rtc_base + GEMINI_RTC_DAYS);
 104
 105        offset = time - (day * 86400 + hour * 3600 + min * 60 + sec);
 106
 107        writel(offset, rtc->rtc_base + GEMINI_RTC_RECORD);
 108        writel(0x01, rtc->rtc_base + GEMINI_RTC_CR);
 109
 110        return 0;
 111}
 112
 113static const struct rtc_class_ops gemini_rtc_ops = {
 114        .read_time     = gemini_rtc_read_time,
 115        .set_time      = gemini_rtc_set_time,
 116};
 117
 118static int gemini_rtc_probe(struct platform_device *pdev)
 119{
 120        struct gemini_rtc *rtc;
 121        struct device *dev = &pdev->dev;
 122        struct resource *res;
 123        int ret;
 124
 125        rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
 126        if (unlikely(!rtc))
 127                return -ENOMEM;
 128        platform_set_drvdata(pdev, rtc);
 129
 130        res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 131        if (!res)
 132                return -ENODEV;
 133
 134        rtc->rtc_irq = res->start;
 135
 136        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 137        if (!res)
 138                return -ENODEV;
 139
 140        rtc->rtc_base = devm_ioremap(dev, res->start,
 141                                     resource_size(res));
 142
 143        ret = devm_request_irq(dev, rtc->rtc_irq, gemini_rtc_interrupt,
 144                               IRQF_SHARED, pdev->name, dev);
 145        if (unlikely(ret))
 146                return ret;
 147
 148        rtc->rtc_dev = rtc_device_register(pdev->name, dev,
 149                                           &gemini_rtc_ops, THIS_MODULE);
 150        return PTR_ERR_OR_ZERO(rtc->rtc_dev);
 151}
 152
 153static int gemini_rtc_remove(struct platform_device *pdev)
 154{
 155        struct gemini_rtc *rtc = platform_get_drvdata(pdev);
 156
 157        rtc_device_unregister(rtc->rtc_dev);
 158
 159        return 0;
 160}
 161
 162static struct platform_driver gemini_rtc_driver = {
 163        .driver         = {
 164                .name   = DRV_NAME,
 165        },
 166        .probe          = gemini_rtc_probe,
 167        .remove         = gemini_rtc_remove,
 168};
 169
 170module_platform_driver_probe(gemini_rtc_driver, gemini_rtc_probe);
 171