linux/drivers/rtc/rtc-aspeed.c
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   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
  10struct 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
  22static 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
  53static 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
  80static const struct rtc_class_ops aspeed_rtc_ops = {
  81        .read_time = aspeed_rtc_read_time,
  82        .set_time = aspeed_rtc_set_time,
  83};
  84
  85static 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 devm_rtc_register_device(rtc->rtc_dev);
 108}
 109
 110static 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};
 116MODULE_DEVICE_TABLE(of, aspeed_rtc_match);
 117
 118static 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
 125module_platform_driver_probe(aspeed_rtc_driver, aspeed_rtc_probe);
 126
 127MODULE_DESCRIPTION("ASPEED RTC driver");
 128MODULE_AUTHOR("Joel Stanley <joel@jms.id.au>");
 129MODULE_LICENSE("GPL");
 130