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 void __iomem *base; 12 }; 13 14 #define RTC_TIME 0x00 15 #define RTC_YEAR 0x04 16 #define RTC_CTRL 0x10 17 18 #define RTC_UNLOCK BIT(1) 19 #define RTC_ENABLE BIT(0) 20 21 static int aspeed_rtc_read_time(struct device *dev, struct rtc_time *tm) 22 { 23 struct aspeed_rtc *rtc = dev_get_drvdata(dev); 24 unsigned int cent, year; 25 u32 reg1, reg2; 26 27 if (!(readl(rtc->base + RTC_CTRL) & RTC_ENABLE)) { 28 dev_dbg(dev, "%s failing as rtc disabled\n", __func__); 29 return -EINVAL; 30 } 31 32 do { 33 reg2 = readl(rtc->base + RTC_YEAR); 34 reg1 = readl(rtc->base + RTC_TIME); 35 } while (reg2 != readl(rtc->base + RTC_YEAR)); 36 37 tm->tm_mday = (reg1 >> 24) & 0x1f; 38 tm->tm_hour = (reg1 >> 16) & 0x1f; 39 tm->tm_min = (reg1 >> 8) & 0x3f; 40 tm->tm_sec = (reg1 >> 0) & 0x3f; 41 42 cent = (reg2 >> 16) & 0x1f; 43 year = (reg2 >> 8) & 0x7f; 44 tm->tm_mon = ((reg2 >> 0) & 0x0f) - 1; 45 tm->tm_year = year + (cent * 100) - 1900; 46 47 dev_dbg(dev, "%s %ptR", __func__, tm); 48 49 return 0; 50 } 51 52 static int aspeed_rtc_set_time(struct device *dev, struct rtc_time *tm) 53 { 54 struct aspeed_rtc *rtc = dev_get_drvdata(dev); 55 u32 reg1, reg2, ctrl; 56 int year, cent; 57 58 cent = (tm->tm_year + 1900) / 100; 59 year = tm->tm_year % 100; 60 61 reg1 = (tm->tm_mday << 24) | (tm->tm_hour << 16) | (tm->tm_min << 8) | 62 tm->tm_sec; 63 64 reg2 = ((cent & 0x1f) << 16) | ((year & 0x7f) << 8) | 65 ((tm->tm_mon + 1) & 0xf); 66 67 ctrl = readl(rtc->base + RTC_CTRL); 68 writel(ctrl | RTC_UNLOCK, rtc->base + RTC_CTRL); 69 70 writel(reg1, rtc->base + RTC_TIME); 71 writel(reg2, rtc->base + RTC_YEAR); 72 73 /* Re-lock and ensure enable is set now that a time is programmed */ 74 writel(ctrl | RTC_ENABLE, rtc->base + RTC_CTRL); 75 76 return 0; 77 } 78 79 static const struct rtc_class_ops aspeed_rtc_ops = { 80 .read_time = aspeed_rtc_read_time, 81 .set_time = aspeed_rtc_set_time, 82 }; 83 84 static int aspeed_rtc_probe(struct platform_device *pdev) 85 { 86 struct aspeed_rtc *rtc; 87 struct rtc_device *rtc_dev; 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_dev = devm_rtc_allocate_device(&pdev->dev); 98 if (IS_ERR(rtc_dev)) 99 return PTR_ERR(rtc_dev); 100 101 platform_set_drvdata(pdev, rtc); 102 103 rtc_dev->ops = &aspeed_rtc_ops; 104 rtc_dev->range_min = RTC_TIMESTAMP_BEGIN_1900; 105 rtc_dev->range_max = 38814989399LL; /* 3199-12-31 23:59:59 */ 106 107 return devm_rtc_register_device(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 = 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"); 130