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 #define DRV_VERSION     "0.2"
  32
  33 MODULE_AUTHOR("Hans Ulli Kroll <ulli.kroll@googlemail.com>");
  34 MODULE_DESCRIPTION("RTC driver for Gemini SoC");
  35 MODULE_LICENSE("GPL");
  36 MODULE_ALIAS("platform:" DRV_NAME);
  37
  38 struct gemini_rtc {
  39         struct rtc_device       *rtc_dev;
  40         void __iomem            *rtc_base;
  41         int                     rtc_irq;
  42 };
  43
  44 enum gemini_rtc_offsets {
  45         GEMINI_RTC_SECOND       = 0x00,
  46         GEMINI_RTC_MINUTE       = 0x04,
  47         GEMINI_RTC_HOUR         = 0x08,
  48         GEMINI_RTC_DAYS         = 0x0C,
  49         GEMINI_RTC_ALARM_SECOND = 0x10,
  50         GEMINI_RTC_ALARM_MINUTE = 0x14,
  51         GEMINI_RTC_ALARM_HOUR   = 0x18,
  52         GEMINI_RTC_RECORD       = 0x1C,
  53         GEMINI_RTC_CR           = 0x20
  54 };
  55
  56 static irqreturn_t gemini_rtc_interrupt(int irq, void *dev)
  57 {
  58         return IRQ_HANDLED;
  59 }
  60
  61 /*
  62  * Looks like the RTC in the Gemini SoC is (totaly) broken
  63  * We can't read/write directly the time from RTC registers.
  64  * We must do some "offset" calculation to get the real time
  65  *
  66  * This FIX works pretty fine and Stormlinksemi aka Cortina-Networks does
  67  * the same thing, without the rtc-lib.c calls.
  68  */
  69
  70 static int gemini_rtc_read_time(struct device *dev, struct rtc_time *tm)
  71 {
  72         struct gemini_rtc *rtc = dev_get_drvdata(dev);
  73
  74         unsigned int  days, hour, min, sec;
  75         unsigned long offset, time;
  76
  77         sec  = readl(rtc->rtc_base + GEMINI_RTC_SECOND);
  78         min  = readl(rtc->rtc_base + GEMINI_RTC_MINUTE);
  79         hour = readl(rtc->rtc_base + GEMINI_RTC_HOUR);
  80         days = readl(rtc->rtc_base + GEMINI_RTC_DAYS);
  81         offset = readl(rtc->rtc_base + GEMINI_RTC_RECORD);
  82
  83         time = offset + days * 86400 + hour * 3600 + min * 60 + sec;
  84
  85         rtc_time_to_tm(time, tm);
  86
  87         return 0;
  88 }
  89
  90 static int gemini_rtc_set_time(struct device *dev, struct rtc_time *tm)
  91 {
  92         struct gemini_rtc *rtc = dev_get_drvdata(dev);
  93         unsigned int sec, min, hour, day;
  94         unsigned long offset, time;
  95
  96         if (tm->tm_year >= 2148)        /* EPOCH Year + 179 */
  97                 return -EINVAL;
  98
  99         rtc_tm_to_time(tm, &time);
 100
 101         sec = readl(rtc->rtc_base + GEMINI_RTC_SECOND);
 102         min = readl(rtc->rtc_base + GEMINI_RTC_MINUTE);
 103         hour = readl(rtc->rtc_base + GEMINI_RTC_HOUR);
 104         day = readl(rtc->rtc_base + GEMINI_RTC_DAYS);
 105
 106         offset = time - (day * 86400 + hour * 3600 + min * 60 + sec);
 107
 108         writel(offset, rtc->rtc_base + GEMINI_RTC_RECORD);
 109         writel(0x01, rtc->rtc_base + GEMINI_RTC_CR);
 110
 111         return 0;
 112 }
 113
 114 static struct rtc_class_ops gemini_rtc_ops = {
 115         .read_time     = gemini_rtc_read_time,
 116         .set_time      = gemini_rtc_set_time,
 117 };
 118
 119 static int gemini_rtc_probe(struct platform_device *pdev)
 120 {
 121         struct gemini_rtc *rtc;
 122         struct device *dev = &pdev->dev;
 123         struct resource *res;
 124         int ret;
 125
 126         rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
 127         if (unlikely(!rtc))
 128                 return -ENOMEM;
 129         platform_set_drvdata(pdev, rtc);
 130
 131         res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 132         if (!res)
 133                 return -ENODEV;
 134
 135         rtc->rtc_irq = res->start;
 136
 137         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 138         if (!res)
 139                 return -ENODEV;
 140
 141         rtc->rtc_base = devm_ioremap(dev, res->start,
 142                                      resource_size(res));
 143
 144         ret = devm_request_irq(dev, rtc->rtc_irq, gemini_rtc_interrupt,
 145                                IRQF_SHARED, pdev->name, dev);
 146         if (unlikely(ret))
 147                 return ret;
 148
 149         rtc->rtc_dev = rtc_device_register(pdev->name, dev,
 150                                            &gemini_rtc_ops, THIS_MODULE);
 151         if (likely(IS_ERR(rtc->rtc_dev)))
 152                 return PTR_ERR(rtc->rtc_dev);
 153
 154         return 0;
 155 }
 156
 157 static int gemini_rtc_remove(struct platform_device *pdev)
 158 {
 159         struct gemini_rtc *rtc = platform_get_drvdata(pdev);
 160
 161         rtc_device_unregister(rtc->rtc_dev);
 162         platform_set_drvdata(pdev, NULL);
 163
 164         return 0;
 165 }
 166
 167 static struct platform_driver gemini_rtc_driver = {
 168         .driver         = {
 169                 .name   = DRV_NAME,
 170         },
 171         .probe          = gemini_rtc_probe,
 172         .remove         = gemini_rtc_remove,
 173 };
 174
 175 module_platform_driver_probe(gemini_rtc_driver, gemini_rtc_probe);