// SPDX-License-Identifier: GPL-2.0+// Copyright 2015 IBM Corp. #include <linux/module.h>#include <linux/of.h>#include <linux/platform_device.h>#include <linux/rtc.h>#include <linux/io.h> struct aspeed_rtc {	void __iomem *base;}; #define RTC_TIME	0x00#define RTC_YEAR	0x04#define RTC_CTRL	0x10 #define RTC_UNLOCK	BIT(1)#define RTC_ENABLE	BIT(0) static int aspeed_rtc_read_time(struct device *dev, struct rtc_time *tm){	struct aspeed_rtc *rtc = dev_get_drvdata(dev);	unsigned int cent, year;	u32 reg1, reg2; 	if (!(readl(rtc->base + RTC_CTRL) & RTC_ENABLE)) {		dev_dbg(dev, "%s failing as rtc disabled\n", __func__);		return -EINVAL;	} 	do {		reg2 = readl(rtc->base + RTC_YEAR);		reg1 = readl(rtc->base + RTC_TIME);	} while (reg2 != readl(rtc->base + RTC_YEAR)); 	tm->tm_mday = (reg1 >> 24) & 0x1f;	tm->tm_hour = (reg1 >> 16) & 0x1f;	tm->tm_min = (reg1 >> 8) & 0x3f;	tm->tm_sec = (reg1 >> 0) & 0x3f; 	cent = (reg2 >> 16) & 0x1f;	year = (reg2 >> 8) & 0x7f;	tm->tm_mon = ((reg2 >>  0) & 0x0f) - 1;	tm->tm_year = year + (cent * 100) - 1900; 	dev_dbg(dev, "%s %ptR", __func__, tm); 	return 0;} static int aspeed_rtc_set_time(struct device *dev, struct rtc_time *tm){	struct aspeed_rtc *rtc = dev_get_drvdata(dev);	u32 reg1, reg2, ctrl;	int year, cent; 	cent = (tm->tm_year + 1900) / 100;	year = tm->tm_year % 100; 	reg1 = (tm->tm_mday << 24) | (tm->tm_hour << 16) | (tm->tm_min << 8) |		tm->tm_sec; 	reg2 = ((cent & 0x1f) << 16) | ((year & 0x7f) << 8) |		((tm->tm_mon + 1) & 0xf); 	ctrl = readl(rtc->base + RTC_CTRL);	writel(ctrl | RTC_UNLOCK, rtc->base + RTC_CTRL); 	writel(reg1, rtc->base + RTC_TIME);	writel(reg2, rtc->base + RTC_YEAR); 	/* Re-lock and ensure enable is set now that a time is programmed */	writel(ctrl | RTC_ENABLE, rtc->base + RTC_CTRL); 	return 0;} static const struct rtc_class_ops aspeed_rtc_ops = {	.read_time = aspeed_rtc_read_time,	.set_time = aspeed_rtc_set_time,}; static int aspeed_rtc_probe(struct platform_device *pdev){	struct aspeed_rtc *rtc;	struct rtc_device *rtc_dev; 	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);	if (!rtc)		return -ENOMEM; 	rtc->base = devm_platform_ioremap_resource(pdev, 0);	if (IS_ERR(rtc->base))		return PTR_ERR(rtc->base); 	rtc_dev = devm_rtc_allocate_device(&pdev->dev);	if (IS_ERR(rtc_dev))		return PTR_ERR(rtc_dev); 	platform_set_drvdata(pdev, rtc); 	rtc_dev->ops = &aspeed_rtc_ops;	rtc_dev->range_min = RTC_TIMESTAMP_BEGIN_1900;	rtc_dev->range_max = 38814989399LL; /* 3199-12-31 23:59:59 */ 	return devm_rtc_register_device(rtc_dev);} static const struct of_device_id aspeed_rtc_match[] = {	{ .compatible = "aspeed,ast2400-rtc", },	{ .compatible = "aspeed,ast2500-rtc", },	{ .compatible = "aspeed,ast2600-rtc", },	{ .compatible = "aspeed,ast2700-rtc", },	{}};MODULE_DEVICE_TABLE(of, aspeed_rtc_match); static struct platform_driver aspeed_rtc_driver = {	.driver = {		.name = "aspeed-rtc",		.of_match_table = aspeed_rtc_match,	},}; module_platform_driver_probe(aspeed_rtc_driver, aspeed_rtc_probe); MODULE_DESCRIPTION("ASPEED RTC driver");MODULE_AUTHOR("Joel Stanley <joel@jms.id.au>");MODULE_LICENSE("GPL");