drivers/rtc/rtc-aspeed.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 // Copyright 2015 IBM Corp.
   3
   4 #include <linux/module.h>
   5 #include <linux/of.h>
   6 #include <linux/platform_device.h>
   7 #include <linux/rtc.h>
   8 #include <linux/io.h>
   9
  10 struct aspeed_rtc {
  11         struct rtc_device *rtc_dev;
  12         void __iomem *base;
  13 };
  14
  15 #define RTC_TIME        0x00
  16 #define RTC_YEAR        0x04
  17 #define RTC_CTRL        0x10
  18
  19 #define RTC_UNLOCK      BIT(1)
  20 #define RTC_ENABLE      BIT(0)
  21
  22 static int aspeed_rtc_read_time(struct device *dev, struct rtc_time *tm)
  23 {
  24         struct aspeed_rtc *rtc = dev_get_drvdata(dev);
  25         unsigned int cent, year;
  26         u32 reg1, reg2;
  27
  28         if (!(readl(rtc->base + RTC_CTRL) & RTC_ENABLE)) {
  29                 dev_dbg(dev, "%s failing as rtc disabled\n", __func__);
  30                 return -EINVAL;
  31         }
  32
  33         do {
  34                 reg2 = readl(rtc->base + RTC_YEAR);
  35                 reg1 = readl(rtc->base + RTC_TIME);
  36         } while (reg2 != readl(rtc->base + RTC_YEAR));
  37
  38         tm->tm_mday = (reg1 >> 24) & 0x1f;
  39         tm->tm_hour = (reg1 >> 16) & 0x1f;
  40         tm->tm_min = (reg1 >> 8) & 0x3f;
  41         tm->tm_sec = (reg1 >> 0) & 0x3f;
  42
  43         cent = (reg2 >> 16) & 0x1f;
  44         year = (reg2 >> 8) & 0x7f;
  45         tm->tm_mon = ((reg2 >>  0) & 0x0f) - 1;
  46         tm->tm_year = year + (cent * 100) - 1900;
  47
  48         dev_dbg(dev, "%s %ptR", __func__, tm);
  49
  50         return 0;
  51 }
  52
  53 static int aspeed_rtc_set_time(struct device *dev, struct rtc_time *tm)
  54 {
  55         struct aspeed_rtc *rtc = dev_get_drvdata(dev);
  56         u32 reg1, reg2, ctrl;
  57         int year, cent;
  58
  59         cent = (tm->tm_year + 1900) / 100;
  60         year = tm->tm_year % 100;
  61
  62         reg1 = (tm->tm_mday << 24) | (tm->tm_hour << 16) | (tm->tm_min << 8) |
  63                 tm->tm_sec;
  64
  65         reg2 = ((cent & 0x1f) << 16) | ((year & 0x7f) << 8) |
  66                 ((tm->tm_mon + 1) & 0xf);
  67
  68         ctrl = readl(rtc->base + RTC_CTRL);
  69         writel(ctrl | RTC_UNLOCK, rtc->base + RTC_CTRL);
  70
  71         writel(reg1, rtc->base + RTC_TIME);
  72         writel(reg2, rtc->base + RTC_YEAR);
  73
  74         /* Re-lock and ensure enable is set now that a time is programmed */
  75         writel(ctrl | RTC_ENABLE, rtc->base + RTC_CTRL);
  76
  77         return 0;
  78 }
  79
  80 static const struct rtc_class_ops aspeed_rtc_ops = {
  81         .read_time = aspeed_rtc_read_time,
  82         .set_time = aspeed_rtc_set_time,
  83 };
  84
  85 static int aspeed_rtc_probe(struct platform_device *pdev)
  86 {
  87         struct aspeed_rtc *rtc;
  88
  89         rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
  90         if (!rtc)
  91                 return -ENOMEM;
  92
  93         rtc->base = devm_platform_ioremap_resource(pdev, 0);
  94         if (IS_ERR(rtc->base))
  95                 return PTR_ERR(rtc->base);
  96
  97         rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
  98         if (IS_ERR(rtc->rtc_dev))
  99                 return PTR_ERR(rtc->rtc_dev);
 100
 101         platform_set_drvdata(pdev, rtc);
 102
 103         rtc->rtc_dev->ops = &aspeed_rtc_ops;
 104         rtc->rtc_dev->range_min = RTC_TIMESTAMP_BEGIN_1900;
 105         rtc->rtc_dev->range_max = 38814989399LL; /* 3199-12-31 23:59:59 */
 106
 107         return rtc_register_device(rtc->rtc_dev);
 108 }
 109
 110 static const struct of_device_id aspeed_rtc_match[] = {
 111         { .compatible = "aspeed,ast2400-rtc", },
 112         { .compatible = "aspeed,ast2500-rtc", },
 113         { .compatible = "aspeed,ast2600-rtc", },
 114         {}
 115 };
 116 MODULE_DEVICE_TABLE(of, aspeed_rtc_match);
 117
 118 static struct platform_driver aspeed_rtc_driver = {
 119         .driver = {
 120                 .name = "aspeed-rtc",
 121                 .of_match_table = of_match_ptr(aspeed_rtc_match),
 122         },
 123 };
 124
 125 module_platform_driver_probe(aspeed_rtc_driver, aspeed_rtc_probe);
 126
 127 MODULE_DESCRIPTION("ASPEED RTC driver");
 128 MODULE_AUTHOR("Joel Stanley <joel@jms.id.au>");
 129 MODULE_LICENSE("GPL");