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 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");