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
  32 MODULE_AUTHOR("Hans Ulli Kroll <ulli.kroll@googlemail.com>");
  33 MODULE_DESCRIPTION("RTC driver for Gemini SoC");
  34 MODULE_LICENSE("GPL");
  35 MODULE_ALIAS("platform:" DRV_NAME);
  36
  37 struct gemini_rtc {
  38         struct rtc_device       *rtc_dev;
  39         void __iomem            *rtc_base;
  40         int                     rtc_irq;
  41 };
  42
  43 enum 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
  55 static 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
  69 static 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
  89 static 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
 113 static const struct rtc_class_ops gemini_rtc_ops = {
 114         .read_time     = gemini_rtc_read_time,
 115         .set_time      = gemini_rtc_set_time,
 116 };
 117
 118 static 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
 153 static 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
 162 static 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
 170 module_platform_driver_probe(gemini_rtc_driver, gemini_rtc_probe);