1/*
  2 * Realtek RTD129x RTC
  3 *
  4 * Copyright (c) 2017 Andreas Färber
  5 *
  6 * SPDX-License-Identifier: GPL-2.0+
  7 */
  8
  9#include <linux/clk.h>
 10#include <linux/io.h>
 11#include <linux/module.h>
 12#include <linux/of.h>
 13#include <linux/of_address.h>
 14#include <linux/platform_device.h>
 15#include <linux/rtc.h>
 16#include <linux/spinlock.h>
 17
 18#define RTD_RTCSEC		0x00
 19#define RTD_RTCMIN		0x04
 20#define RTD_RTCHR		0x08
 21#define RTD_RTCDATE1		0x0c
 22#define RTD_RTCDATE2		0x10
 23#define RTD_RTCACR		0x28
 24#define RTD_RTCEN		0x2c
 25#define RTD_RTCCR		0x30
 26
 27#define RTD_RTCSEC_RTCSEC_MASK		0x7f
 28
 29#define RTD_RTCMIN_RTCMIN_MASK		0x3f
 30
 31#define RTD_RTCHR_RTCHR_MASK		0x1f
 32
 33#define RTD_RTCDATE1_RTCDATE1_MASK	0xff
 34
 35#define RTD_RTCDATE2_RTCDATE2_MASK	0x7f
 36
 37#define RTD_RTCACR_RTCPWR		BIT(7)
 38
 39#define RTD_RTCEN_RTCEN_MASK		0xff
 40
 41#define RTD_RTCCR_RTCRST		BIT(6)
 42
 43struct rtd119x_rtc {
 44	void __iomem *base;
 45	struct clk *clk;
 46	struct rtc_device *rtcdev;
 47	unsigned int base_year;
 48};
 49
 50static inline int rtd119x_rtc_days_in_year(int year)
 51{
 52	return 365 + (is_leap_year(year) ? 1 : 0);
 53}
 54
 55static void rtd119x_rtc_reset(struct device *dev)
 56{
 57	struct rtd119x_rtc *data = dev_get_drvdata(dev);
 58	u32 val;
 59
 60	val = readl_relaxed(data->base + RTD_RTCCR);
 61	val |= RTD_RTCCR_RTCRST;
 62	writel_relaxed(val, data->base + RTD_RTCCR);
 63
 64	val &= ~RTD_RTCCR_RTCRST;
 65	writel(val, data->base + RTD_RTCCR);
 66}
 67
 68static void rtd119x_rtc_set_enabled(struct device *dev, bool enable)
 69{
 70	struct rtd119x_rtc *data = dev_get_drvdata(dev);
 71	u32 val;
 72
 73	val = readl_relaxed(data->base + RTD_RTCEN);
 74	if (enable) {
 75		if ((val & RTD_RTCEN_RTCEN_MASK) == 0x5a)
 76			return;
 77		writel_relaxed(0x5a, data->base + RTD_RTCEN);
 78	} else {
 79		writel_relaxed(0, data->base + RTD_RTCEN);
 80	}
 81}
 82
 83static int rtd119x_rtc_read_time(struct device *dev, struct rtc_time *tm)
 84{
 85	struct rtd119x_rtc *data = dev_get_drvdata(dev);
 86	s32 day;
 87	u32 sec;
 88	unsigned int year;
 89	int tries = 0;
 90
 91	while (true) {
 92		tm->tm_sec = (readl_relaxed(data->base + RTD_RTCSEC) & RTD_RTCSEC_RTCSEC_MASK) >> 1;
 93		tm->tm_min  = readl_relaxed(data->base + RTD_RTCMIN) & RTD_RTCMIN_RTCMIN_MASK;
 94		tm->tm_hour = readl_relaxed(data->base + RTD_RTCHR) & RTD_RTCHR_RTCHR_MASK;
 95		day  =  readl_relaxed(data->base + RTD_RTCDATE1) & RTD_RTCDATE1_RTCDATE1_MASK;
 96		day |= (readl_relaxed(data->base + RTD_RTCDATE2) & RTD_RTCDATE2_RTCDATE2_MASK) << 8;
 97		sec  = (readl_relaxed(data->base + RTD_RTCSEC) & RTD_RTCSEC_RTCSEC_MASK) >> 1;
 98		tries++;
 99
100		if (sec == tm->tm_sec)
101			break;
102
103		if (tries >= 3)
104			return -EINVAL;
105	}
106	if (tries > 1)
107		dev_dbg(dev, "%s: needed %i tries\n", __func__, tries);
108
109	year = data->base_year;
110	while (day >= rtd119x_rtc_days_in_year(year)) {
111		day -= rtd119x_rtc_days_in_year(year);
112		year++;
113	}
114	tm->tm_year = year - 1900;
115	tm->tm_yday = day;
116
117	tm->tm_mon = 0;
118	while (day >= rtc_month_days(tm->tm_mon, year)) {
119		day -= rtc_month_days(tm->tm_mon, year);
120		tm->tm_mon++;
121	}
122	tm->tm_mday = day + 1;
123
124	return 0;
125}
126
127static int rtd119x_rtc_set_time(struct device *dev, struct rtc_time *tm)
128{
129	struct rtd119x_rtc *data = dev_get_drvdata(dev);
130	unsigned int day;
131	int i;
132
133	if (1900 + tm->tm_year < data->base_year)
134		return -EINVAL;
135
136	day = 0;
137	for (i = data->base_year; i < 1900 + tm->tm_year; i++)
138		day += rtd119x_rtc_days_in_year(i);
139
140	day += tm->tm_yday;
141	if (day > 0x7fff)
142		return -EINVAL;
143
144	rtd119x_rtc_set_enabled(dev, false);
145
146	writel_relaxed((tm->tm_sec << 1) & RTD_RTCSEC_RTCSEC_MASK, data->base + RTD_RTCSEC);
147	writel_relaxed(tm->tm_min & RTD_RTCMIN_RTCMIN_MASK, data->base + RTD_RTCMIN);
148	writel_relaxed(tm->tm_hour & RTD_RTCHR_RTCHR_MASK, data->base + RTD_RTCHR);
149	writel_relaxed(day & RTD_RTCDATE1_RTCDATE1_MASK, data->base + RTD_RTCDATE1);
150	writel_relaxed((day >> 8) & RTD_RTCDATE2_RTCDATE2_MASK, data->base + RTD_RTCDATE2);
151
152	rtd119x_rtc_set_enabled(dev, true);
153
154	return 0;
155}
156
157static const struct rtc_class_ops rtd119x_rtc_ops = {
158	.read_time	= rtd119x_rtc_read_time,
159	.set_time	= rtd119x_rtc_set_time,
160};
161
162static const struct of_device_id rtd119x_rtc_dt_ids[] = {
163	 { .compatible = "realtek,rtd1295-rtc" },
164	 { }
165};
166
167static int rtd119x_rtc_probe(struct platform_device *pdev)
168{
169	struct rtd119x_rtc *data;
170	struct resource *res;
171	u32 val;
172	int ret;
173
174	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
175	if (!data)
176		return -ENOMEM;
177
178	platform_set_drvdata(pdev, data);
179	data->base_year = 2014;
180
181	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
182	data->base = devm_ioremap_resource(&pdev->dev, res);
183	if (IS_ERR(data->base))
184		return PTR_ERR(data->base);
185
186	data->clk = of_clk_get(pdev->dev.of_node, 0);
187	if (IS_ERR(data->clk))
188		return PTR_ERR(data->clk);
189
190	ret = clk_prepare_enable(data->clk);
191	if (ret) {
192		clk_put(data->clk);
193		return ret;
194	}
195
196	val = readl_relaxed(data->base + RTD_RTCACR);
197	if (!(val & RTD_RTCACR_RTCPWR)) {
198		writel_relaxed(RTD_RTCACR_RTCPWR, data->base + RTD_RTCACR);
199
200		rtd119x_rtc_reset(&pdev->dev);
201
202		writel_relaxed(0, data->base + RTD_RTCMIN);
203		writel_relaxed(0, data->base + RTD_RTCHR);
204		writel_relaxed(0, data->base + RTD_RTCDATE1);
205		writel_relaxed(0, data->base + RTD_RTCDATE2);
206	}
207
208	rtd119x_rtc_set_enabled(&pdev->dev, true);
209
210	data->rtcdev = devm_rtc_device_register(&pdev->dev, "rtc",
211						&rtd119x_rtc_ops, THIS_MODULE);
212	if (IS_ERR(data->rtcdev)) {
213		dev_err(&pdev->dev, "failed to register rtc device");
214		clk_disable_unprepare(data->clk);
215		clk_put(data->clk);
216		return PTR_ERR(data->rtcdev);
217	}
218
219	return 0;
220}
221
222static int rtd119x_rtc_remove(struct platform_device *pdev)
223{
224	struct rtd119x_rtc *data = platform_get_drvdata(pdev);
225
226	rtd119x_rtc_set_enabled(&pdev->dev, false);
227
228	clk_disable_unprepare(data->clk);
229	clk_put(data->clk);
230
231	return 0;
232}
233
234static struct platform_driver rtd119x_rtc_driver = {
235	.probe = rtd119x_rtc_probe,
236	.remove = rtd119x_rtc_remove,
237	.driver = {
238		.name = "rtd1295-rtc",
239		.of_match_table	= rtd119x_rtc_dt_ids,
240	},
241};
242builtin_platform_driver(rtd119x_rtc_driver);