1 /*
2  * drivers/rtc/rtc-vt8500.c
3  *
4  *  Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
5  *
6  * Based on rtc-pxa.c
7  *
8  * This software is licensed under the terms of the GNU General Public
9  * License version 2, as published by the Free Software Foundation, and
10  * may be copied, distributed, and modified under those terms.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  */
17 
18 #include <linux/module.h>
19 #include <linux/rtc.h>
20 #include <linux/init.h>
21 #include <linux/interrupt.h>
22 #include <linux/io.h>
23 #include <linux/bcd.h>
24 #include <linux/platform_device.h>
25 #include <linux/slab.h>
26 #include <linux/of.h>
27 
28 /*
29  * Register definitions
30  */
31 #define VT8500_RTC_TS		0x00	/* Time set */
32 #define VT8500_RTC_DS		0x04	/* Date set */
33 #define VT8500_RTC_AS		0x08	/* Alarm set */
34 #define VT8500_RTC_CR		0x0c	/* Control */
35 #define VT8500_RTC_TR		0x10	/* Time read */
36 #define VT8500_RTC_DR		0x14	/* Date read */
37 #define VT8500_RTC_WS		0x18	/* Write status */
38 #define VT8500_RTC_CL		0x20	/* Calibration */
39 #define VT8500_RTC_IS		0x24	/* Interrupt status */
40 #define VT8500_RTC_ST		0x28	/* Status */
41 
42 #define INVALID_TIME_BIT	(1 << 31)
43 
44 #define DATE_CENTURY_S		19
45 #define DATE_YEAR_S		11
46 #define DATE_YEAR_MASK		(0xff << DATE_YEAR_S)
47 #define DATE_MONTH_S		6
48 #define DATE_MONTH_MASK		(0x1f << DATE_MONTH_S)
49 #define DATE_DAY_MASK		0x3f
50 
51 #define TIME_DOW_S		20
52 #define TIME_DOW_MASK		(0x07 << TIME_DOW_S)
53 #define TIME_HOUR_S		14
54 #define TIME_HOUR_MASK		(0x3f << TIME_HOUR_S)
55 #define TIME_MIN_S		7
56 #define TIME_MIN_MASK		(0x7f << TIME_MIN_S)
57 #define TIME_SEC_MASK		0x7f
58 
59 #define ALARM_DAY_S		20
60 #define ALARM_DAY_MASK		(0x3f << ALARM_DAY_S)
61 
62 #define ALARM_DAY_BIT		(1 << 29)
63 #define ALARM_HOUR_BIT		(1 << 28)
64 #define ALARM_MIN_BIT		(1 << 27)
65 #define ALARM_SEC_BIT		(1 << 26)
66 
67 #define ALARM_ENABLE_MASK	(ALARM_DAY_BIT \
68 				| ALARM_HOUR_BIT \
69 				| ALARM_MIN_BIT \
70 				| ALARM_SEC_BIT)
71 
72 #define VT8500_RTC_CR_ENABLE	(1 << 0)	/* Enable RTC */
73 #define VT8500_RTC_CR_12H	(1 << 1)	/* 12h time format */
74 #define VT8500_RTC_CR_SM_ENABLE	(1 << 2)	/* Enable periodic irqs */
75 #define VT8500_RTC_CR_SM_SEC	(1 << 3)	/* 0: 1Hz/60, 1: 1Hz */
76 #define VT8500_RTC_CR_CALIB	(1 << 4)	/* Enable calibration */
77 
78 #define VT8500_RTC_IS_ALARM	(1 << 0)	/* Alarm interrupt status */
79 
80 struct vt8500_rtc {
81 	void __iomem		*regbase;
82 	int			irq_alarm;
83 	struct rtc_device	*rtc;
84 	spinlock_t		lock;		/* Protects this structure */
85 };
86 
vt8500_rtc_irq(int irq,void * dev_id)87 static irqreturn_t vt8500_rtc_irq(int irq, void *dev_id)
88 {
89 	struct vt8500_rtc *vt8500_rtc = dev_id;
90 	u32 isr;
91 	unsigned long events = 0;
92 
93 	spin_lock(&vt8500_rtc->lock);
94 
95 	/* clear interrupt sources */
96 	isr = readl(vt8500_rtc->regbase + VT8500_RTC_IS);
97 	writel(isr, vt8500_rtc->regbase + VT8500_RTC_IS);
98 
99 	spin_unlock(&vt8500_rtc->lock);
100 
101 	if (isr & VT8500_RTC_IS_ALARM)
102 		events |= RTC_AF | RTC_IRQF;
103 
104 	rtc_update_irq(vt8500_rtc->rtc, 1, events);
105 
106 	return IRQ_HANDLED;
107 }
108 
vt8500_rtc_read_time(struct device * dev,struct rtc_time * tm)109 static int vt8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
110 {
111 	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
112 	u32 date, time;
113 
114 	date = readl(vt8500_rtc->regbase + VT8500_RTC_DR);
115 	time = readl(vt8500_rtc->regbase + VT8500_RTC_TR);
116 
117 	tm->tm_sec = bcd2bin(time & TIME_SEC_MASK);
118 	tm->tm_min = bcd2bin((time & TIME_MIN_MASK) >> TIME_MIN_S);
119 	tm->tm_hour = bcd2bin((time & TIME_HOUR_MASK) >> TIME_HOUR_S);
120 	tm->tm_mday = bcd2bin(date & DATE_DAY_MASK);
121 	tm->tm_mon = bcd2bin((date & DATE_MONTH_MASK) >> DATE_MONTH_S) - 1;
122 	tm->tm_year = bcd2bin((date & DATE_YEAR_MASK) >> DATE_YEAR_S)
123 			+ ((date >> DATE_CENTURY_S) & 1 ? 200 : 100);
124 	tm->tm_wday = (time & TIME_DOW_MASK) >> TIME_DOW_S;
125 
126 	return 0;
127 }
128 
vt8500_rtc_set_time(struct device * dev,struct rtc_time * tm)129 static int vt8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
130 {
131 	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
132 
133 	if (tm->tm_year < 100) {
134 		dev_warn(dev, "Only years 2000-2199 are supported by the "
135 			      "hardware!\n");
136 		return -EINVAL;
137 	}
138 
139 	writel((bin2bcd(tm->tm_year % 100) << DATE_YEAR_S)
140 		| (bin2bcd(tm->tm_mon + 1) << DATE_MONTH_S)
141 		| (bin2bcd(tm->tm_mday))
142 		| ((tm->tm_year >= 200) << DATE_CENTURY_S),
143 		vt8500_rtc->regbase + VT8500_RTC_DS);
144 	writel((bin2bcd(tm->tm_wday) << TIME_DOW_S)
145 		| (bin2bcd(tm->tm_hour) << TIME_HOUR_S)
146 		| (bin2bcd(tm->tm_min) << TIME_MIN_S)
147 		| (bin2bcd(tm->tm_sec)),
148 		vt8500_rtc->regbase + VT8500_RTC_TS);
149 
150 	return 0;
151 }
152 
vt8500_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alrm)153 static int vt8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
154 {
155 	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
156 	u32 isr, alarm;
157 
158 	alarm = readl(vt8500_rtc->regbase + VT8500_RTC_AS);
159 	isr = readl(vt8500_rtc->regbase + VT8500_RTC_IS);
160 
161 	alrm->time.tm_mday = bcd2bin((alarm & ALARM_DAY_MASK) >> ALARM_DAY_S);
162 	alrm->time.tm_hour = bcd2bin((alarm & TIME_HOUR_MASK) >> TIME_HOUR_S);
163 	alrm->time.tm_min = bcd2bin((alarm & TIME_MIN_MASK) >> TIME_MIN_S);
164 	alrm->time.tm_sec = bcd2bin((alarm & TIME_SEC_MASK));
165 
166 	alrm->enabled = (alarm & ALARM_ENABLE_MASK) ? 1 : 0;
167 	alrm->pending = (isr & VT8500_RTC_IS_ALARM) ? 1 : 0;
168 
169 	return rtc_valid_tm(&alrm->time);
170 }
171 
vt8500_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alrm)172 static int vt8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
173 {
174 	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
175 
176 	writel((alrm->enabled ? ALARM_ENABLE_MASK : 0)
177 		| (bin2bcd(alrm->time.tm_mday) << ALARM_DAY_S)
178 		| (bin2bcd(alrm->time.tm_hour) << TIME_HOUR_S)
179 		| (bin2bcd(alrm->time.tm_min) << TIME_MIN_S)
180 		| (bin2bcd(alrm->time.tm_sec)),
181 		vt8500_rtc->regbase + VT8500_RTC_AS);
182 
183 	return 0;
184 }
185 
vt8500_alarm_irq_enable(struct device * dev,unsigned int enabled)186 static int vt8500_alarm_irq_enable(struct device *dev, unsigned int enabled)
187 {
188 	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
189 	unsigned long tmp = readl(vt8500_rtc->regbase + VT8500_RTC_AS);
190 
191 	if (enabled)
192 		tmp |= ALARM_ENABLE_MASK;
193 	else
194 		tmp &= ~ALARM_ENABLE_MASK;
195 
196 	writel(tmp, vt8500_rtc->regbase + VT8500_RTC_AS);
197 	return 0;
198 }
199 
200 static const struct rtc_class_ops vt8500_rtc_ops = {
201 	.read_time = vt8500_rtc_read_time,
202 	.set_time = vt8500_rtc_set_time,
203 	.read_alarm = vt8500_rtc_read_alarm,
204 	.set_alarm = vt8500_rtc_set_alarm,
205 	.alarm_irq_enable = vt8500_alarm_irq_enable,
206 };
207 
vt8500_rtc_probe(struct platform_device * pdev)208 static int vt8500_rtc_probe(struct platform_device *pdev)
209 {
210 	struct vt8500_rtc *vt8500_rtc;
211 	struct resource	*res;
212 	int ret;
213 
214 	vt8500_rtc = devm_kzalloc(&pdev->dev,
215 			   sizeof(struct vt8500_rtc), GFP_KERNEL);
216 	if (!vt8500_rtc)
217 		return -ENOMEM;
218 
219 	spin_lock_init(&vt8500_rtc->lock);
220 	platform_set_drvdata(pdev, vt8500_rtc);
221 
222 	vt8500_rtc->irq_alarm = platform_get_irq(pdev, 0);
223 	if (vt8500_rtc->irq_alarm < 0) {
224 		dev_err(&pdev->dev, "No alarm IRQ resource defined\n");
225 		return vt8500_rtc->irq_alarm;
226 	}
227 
228 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
229 	vt8500_rtc->regbase = devm_ioremap_resource(&pdev->dev, res);
230 	if (IS_ERR(vt8500_rtc->regbase))
231 		return PTR_ERR(vt8500_rtc->regbase);
232 
233 	/* Enable RTC and set it to 24-hour mode */
234 	writel(VT8500_RTC_CR_ENABLE,
235 	       vt8500_rtc->regbase + VT8500_RTC_CR);
236 
237 	vt8500_rtc->rtc = devm_rtc_device_register(&pdev->dev, "vt8500-rtc",
238 					      &vt8500_rtc_ops, THIS_MODULE);
239 	if (IS_ERR(vt8500_rtc->rtc)) {
240 		ret = PTR_ERR(vt8500_rtc->rtc);
241 		dev_err(&pdev->dev,
242 			"Failed to register RTC device -> %d\n", ret);
243 		goto err_return;
244 	}
245 
246 	ret = devm_request_irq(&pdev->dev, vt8500_rtc->irq_alarm,
247 				vt8500_rtc_irq, 0, "rtc alarm", vt8500_rtc);
248 	if (ret < 0) {
249 		dev_err(&pdev->dev, "can't get irq %i, err %d\n",
250 			vt8500_rtc->irq_alarm, ret);
251 		goto err_return;
252 	}
253 
254 	return 0;
255 
256 err_return:
257 	return ret;
258 }
259 
vt8500_rtc_remove(struct platform_device * pdev)260 static int vt8500_rtc_remove(struct platform_device *pdev)
261 {
262 	struct vt8500_rtc *vt8500_rtc = platform_get_drvdata(pdev);
263 
264 	/* Disable alarm matching */
265 	writel(0, vt8500_rtc->regbase + VT8500_RTC_IS);
266 
267 	return 0;
268 }
269 
270 static const struct of_device_id wmt_dt_ids[] = {
271 	{ .compatible = "via,vt8500-rtc", },
272 	{}
273 };
274 MODULE_DEVICE_TABLE(of, wmt_dt_ids);
275 
276 static struct platform_driver vt8500_rtc_driver = {
277 	.probe		= vt8500_rtc_probe,
278 	.remove		= vt8500_rtc_remove,
279 	.driver		= {
280 		.name	= "vt8500-rtc",
281 		.of_match_table = wmt_dt_ids,
282 	},
283 };
284 
285 module_platform_driver(vt8500_rtc_driver);
286 
287 MODULE_AUTHOR("Alexey Charkov <alchark@gmail.com>");
288 MODULE_DESCRIPTION("VIA VT8500 SoC Realtime Clock Driver (RTC)");
289 MODULE_LICENSE("GPL v2");
290 MODULE_ALIAS("platform:vt8500-rtc");
291