drivers/rtc/rtc-aspeed.c

0001 // SPDX-License-Identifier: GPL-2.0+
0002 // Copyright 2015 IBM Corp.
0003
0004 #include <linux/module.h>
0005 #include <linux/of.h>
0006 #include <linux/platform_device.h>
0007 #include <linux/rtc.h>
0008 #include <linux/io.h>
0009
0010 struct aspeed_rtc {
0011     struct rtc_device *rtc_dev;
0012     void __iomem *base;
0013 };
0014
0015 #define RTC_TIME    0x00
0016 #define RTC_YEAR    0x04
0017 #define RTC_CTRL    0x10
0018
0019 #define RTC_UNLOCK  BIT(1)
0020 #define RTC_ENABLE  BIT(0)
0021
0022 static int aspeed_rtc_read_time(struct device *dev, struct rtc_time *tm)
0023 {
0024     struct aspeed_rtc *rtc = dev_get_drvdata(dev);
0025     unsigned int cent, year;
0026     u32 reg1, reg2;
0027
0028     if (!(readl(rtc->base + RTC_CTRL) & RTC_ENABLE)) {
0029         dev_dbg(dev, "%s failing as rtc disabled\n", __func__);
0030         return -EINVAL;
0031     }
0032
0033     do {
0034         reg2 = readl(rtc->base + RTC_YEAR);
0035         reg1 = readl(rtc->base + RTC_TIME);
0036     } while (reg2 != readl(rtc->base + RTC_YEAR));
0037
0038     tm->tm_mday = (reg1 >> 24) & 0x1f;
0039     tm->tm_hour = (reg1 >> 16) & 0x1f;
0040     tm->tm_min = (reg1 >> 8) & 0x3f;
0041     tm->tm_sec = (reg1 >> 0) & 0x3f;
0042
0043     cent = (reg2 >> 16) & 0x1f;
0044     year = (reg2 >> 8) & 0x7f;
0045     tm->tm_mon = ((reg2 >>  0) & 0x0f) - 1;
0046     tm->tm_year = year + (cent * 100) - 1900;
0047
0048     dev_dbg(dev, "%s %ptR", __func__, tm);
0049
0050     return 0;
0051 }
0052
0053 static int aspeed_rtc_set_time(struct device *dev, struct rtc_time *tm)
0054 {
0055     struct aspeed_rtc *rtc = dev_get_drvdata(dev);
0056     u32 reg1, reg2, ctrl;
0057     int year, cent;
0058
0059     cent = (tm->tm_year + 1900) / 100;
0060     year = tm->tm_year % 100;
0061
0062     reg1 = (tm->tm_mday << 24) | (tm->tm_hour << 16) | (tm->tm_min << 8) |
0063         tm->tm_sec;
0064
0065     reg2 = ((cent & 0x1f) << 16) | ((year & 0x7f) << 8) |
0066         ((tm->tm_mon + 1) & 0xf);
0067
0068     ctrl = readl(rtc->base + RTC_CTRL);
0069     writel(ctrl | RTC_UNLOCK, rtc->base + RTC_CTRL);
0070
0071     writel(reg1, rtc->base + RTC_TIME);
0072     writel(reg2, rtc->base + RTC_YEAR);
0073
0074     /* Re-lock and ensure enable is set now that a time is programmed */
0075     writel(ctrl | RTC_ENABLE, rtc->base + RTC_CTRL);
0076
0077     return 0;
0078 }
0079
0080 static const struct rtc_class_ops aspeed_rtc_ops = {
0081     .read_time = aspeed_rtc_read_time,
0082     .set_time = aspeed_rtc_set_time,
0083 };
0084
0085 static int aspeed_rtc_probe(struct platform_device *pdev)
0086 {
0087     struct aspeed_rtc *rtc;
0088
0089     rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
0090     if (!rtc)
0091         return -ENOMEM;
0092
0093     rtc->base = devm_platform_ioremap_resource(pdev, 0);
0094     if (IS_ERR(rtc->base))
0095         return PTR_ERR(rtc->base);
0096
0097     rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
0098     if (IS_ERR(rtc->rtc_dev))
0099         return PTR_ERR(rtc->rtc_dev);
0100
0101     platform_set_drvdata(pdev, rtc);
0102
0103     rtc->rtc_dev->ops = &aspeed_rtc_ops;
0104     rtc->rtc_dev->range_min = RTC_TIMESTAMP_BEGIN_1900;
0105     rtc->rtc_dev->range_max = 38814989399LL; /* 3199-12-31 23:59:59 */
0106
0107     return devm_rtc_register_device(rtc->rtc_dev);
0108 }
0109
0110 static const struct of_device_id aspeed_rtc_match[] = {
0111     { .compatible = "aspeed,ast2400-rtc", },
0112     { .compatible = "aspeed,ast2500-rtc", },
0113     { .compatible = "aspeed,ast2600-rtc", },
0114     {}
0115 };
0116 MODULE_DEVICE_TABLE(of, aspeed_rtc_match);
0117
0118 static struct platform_driver aspeed_rtc_driver = {
0119     .driver = {
0120         .name = "aspeed-rtc",
0121         .of_match_table = of_match_ptr(aspeed_rtc_match),
0122     },
0123 };
0124
0125 module_platform_driver_probe(aspeed_rtc_driver, aspeed_rtc_probe);
0126
0127 MODULE_DESCRIPTION("ASPEED RTC driver");
0128 MODULE_AUTHOR("Joel Stanley <joel@jms.id.au>");
0129 MODULE_LICENSE("GPL");