1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * An rtc driver for the Dallas DS1553
4 *
5 * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
6 */
7
8 #include <linux/bcd.h>
9 #include <linux/init.h>
10 #include <linux/kernel.h>
11 #include <linux/gfp.h>
12 #include <linux/delay.h>
13 #include <linux/jiffies.h>
14 #include <linux/interrupt.h>
15 #include <linux/rtc.h>
16 #include <linux/platform_device.h>
17 #include <linux/io.h>
18 #include <linux/module.h>
19
20 #define RTC_REG_SIZE 0x2000
21 #define RTC_OFFSET 0x1ff0
22
23 #define RTC_FLAGS (RTC_OFFSET + 0)
24 #define RTC_SECONDS_ALARM (RTC_OFFSET + 2)
25 #define RTC_MINUTES_ALARM (RTC_OFFSET + 3)
26 #define RTC_HOURS_ALARM (RTC_OFFSET + 4)
27 #define RTC_DATE_ALARM (RTC_OFFSET + 5)
28 #define RTC_INTERRUPTS (RTC_OFFSET + 6)
29 #define RTC_WATCHDOG (RTC_OFFSET + 7)
30 #define RTC_CONTROL (RTC_OFFSET + 8)
31 #define RTC_CENTURY (RTC_OFFSET + 8)
32 #define RTC_SECONDS (RTC_OFFSET + 9)
33 #define RTC_MINUTES (RTC_OFFSET + 10)
34 #define RTC_HOURS (RTC_OFFSET + 11)
35 #define RTC_DAY (RTC_OFFSET + 12)
36 #define RTC_DATE (RTC_OFFSET + 13)
37 #define RTC_MONTH (RTC_OFFSET + 14)
38 #define RTC_YEAR (RTC_OFFSET + 15)
39
40 #define RTC_CENTURY_MASK 0x3f
41 #define RTC_SECONDS_MASK 0x7f
42 #define RTC_DAY_MASK 0x07
43
44 /* Bits in the Control/Century register */
45 #define RTC_WRITE 0x80
46 #define RTC_READ 0x40
47
48 /* Bits in the Seconds register */
49 #define RTC_STOP 0x80
50
51 /* Bits in the Flags register */
52 #define RTC_FLAGS_AF 0x40
53 #define RTC_FLAGS_BLF 0x10
54
55 /* Bits in the Interrupts register */
56 #define RTC_INTS_AE 0x80
57
58 struct rtc_plat_data {
59 struct rtc_device *rtc;
60 void __iomem *ioaddr;
61 unsigned long last_jiffies;
62 int irq;
63 unsigned int irqen;
64 int alrm_sec;
65 int alrm_min;
66 int alrm_hour;
67 int alrm_mday;
68 spinlock_t lock;
69 };
70
ds1553_rtc_set_time(struct device * dev,struct rtc_time * tm)71 static int ds1553_rtc_set_time(struct device *dev, struct rtc_time *tm)
72 {
73 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
74 void __iomem *ioaddr = pdata->ioaddr;
75 u8 century;
76
77 century = bin2bcd((tm->tm_year + 1900) / 100);
78
79 writeb(RTC_WRITE, pdata->ioaddr + RTC_CONTROL);
80
81 writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
82 writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
83 writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
84 writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
85 writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
86 writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
87 writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
88
89 /* RTC_CENTURY and RTC_CONTROL share same register */
90 writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
91 writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
92 return 0;
93 }
94
ds1553_rtc_read_time(struct device * dev,struct rtc_time * tm)95 static int ds1553_rtc_read_time(struct device *dev, struct rtc_time *tm)
96 {
97 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
98 void __iomem *ioaddr = pdata->ioaddr;
99 unsigned int year, month, day, hour, minute, second, week;
100 unsigned int century;
101
102 /* give enough time to update RTC in case of continuous read */
103 if (pdata->last_jiffies == jiffies)
104 msleep(1);
105 pdata->last_jiffies = jiffies;
106 writeb(RTC_READ, ioaddr + RTC_CONTROL);
107 second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
108 minute = readb(ioaddr + RTC_MINUTES);
109 hour = readb(ioaddr + RTC_HOURS);
110 day = readb(ioaddr + RTC_DATE);
111 week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
112 month = readb(ioaddr + RTC_MONTH);
113 year = readb(ioaddr + RTC_YEAR);
114 century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
115 writeb(0, ioaddr + RTC_CONTROL);
116 tm->tm_sec = bcd2bin(second);
117 tm->tm_min = bcd2bin(minute);
118 tm->tm_hour = bcd2bin(hour);
119 tm->tm_mday = bcd2bin(day);
120 tm->tm_wday = bcd2bin(week);
121 tm->tm_mon = bcd2bin(month) - 1;
122 /* year is 1900 + tm->tm_year */
123 tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
124
125 return 0;
126 }
127
ds1553_rtc_update_alarm(struct rtc_plat_data * pdata)128 static void ds1553_rtc_update_alarm(struct rtc_plat_data *pdata)
129 {
130 void __iomem *ioaddr = pdata->ioaddr;
131 unsigned long flags;
132
133 spin_lock_irqsave(&pdata->lock, flags);
134 writeb(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
135 0x80 : bin2bcd(pdata->alrm_mday),
136 ioaddr + RTC_DATE_ALARM);
137 writeb(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
138 0x80 : bin2bcd(pdata->alrm_hour),
139 ioaddr + RTC_HOURS_ALARM);
140 writeb(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
141 0x80 : bin2bcd(pdata->alrm_min),
142 ioaddr + RTC_MINUTES_ALARM);
143 writeb(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
144 0x80 : bin2bcd(pdata->alrm_sec),
145 ioaddr + RTC_SECONDS_ALARM);
146 writeb(pdata->irqen ? RTC_INTS_AE : 0, ioaddr + RTC_INTERRUPTS);
147 readb(ioaddr + RTC_FLAGS); /* clear interrupts */
148 spin_unlock_irqrestore(&pdata->lock, flags);
149 }
150
ds1553_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alrm)151 static int ds1553_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
152 {
153 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
154
155 if (pdata->irq <= 0)
156 return -EINVAL;
157 pdata->alrm_mday = alrm->time.tm_mday;
158 pdata->alrm_hour = alrm->time.tm_hour;
159 pdata->alrm_min = alrm->time.tm_min;
160 pdata->alrm_sec = alrm->time.tm_sec;
161 if (alrm->enabled)
162 pdata->irqen |= RTC_AF;
163 ds1553_rtc_update_alarm(pdata);
164 return 0;
165 }
166
ds1553_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alrm)167 static int ds1553_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
168 {
169 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
170
171 if (pdata->irq <= 0)
172 return -EINVAL;
173 alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
174 alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
175 alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
176 alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
177 alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
178 return 0;
179 }
180
ds1553_rtc_interrupt(int irq,void * dev_id)181 static irqreturn_t ds1553_rtc_interrupt(int irq, void *dev_id)
182 {
183 struct platform_device *pdev = dev_id;
184 struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
185 void __iomem *ioaddr = pdata->ioaddr;
186 unsigned long events = 0;
187
188 spin_lock(&pdata->lock);
189 /* read and clear interrupt */
190 if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_AF) {
191 events = RTC_IRQF;
192 if (readb(ioaddr + RTC_SECONDS_ALARM) & 0x80)
193 events |= RTC_UF;
194 else
195 events |= RTC_AF;
196 rtc_update_irq(pdata->rtc, 1, events);
197 }
198 spin_unlock(&pdata->lock);
199 return events ? IRQ_HANDLED : IRQ_NONE;
200 }
201
ds1553_rtc_alarm_irq_enable(struct device * dev,unsigned int enabled)202 static int ds1553_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
203 {
204 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
205
206 if (pdata->irq <= 0)
207 return -EINVAL;
208 if (enabled)
209 pdata->irqen |= RTC_AF;
210 else
211 pdata->irqen &= ~RTC_AF;
212 ds1553_rtc_update_alarm(pdata);
213 return 0;
214 }
215
216 static const struct rtc_class_ops ds1553_rtc_ops = {
217 .read_time = ds1553_rtc_read_time,
218 .set_time = ds1553_rtc_set_time,
219 .read_alarm = ds1553_rtc_read_alarm,
220 .set_alarm = ds1553_rtc_set_alarm,
221 .alarm_irq_enable = ds1553_rtc_alarm_irq_enable,
222 };
223
ds1553_nvram_read(void * priv,unsigned int pos,void * val,size_t bytes)224 static int ds1553_nvram_read(void *priv, unsigned int pos, void *val,
225 size_t bytes)
226 {
227 struct platform_device *pdev = priv;
228 struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
229 void __iomem *ioaddr = pdata->ioaddr;
230 u8 *buf = val;
231
232 for (; bytes; bytes--)
233 *buf++ = readb(ioaddr + pos++);
234 return 0;
235 }
236
ds1553_nvram_write(void * priv,unsigned int pos,void * val,size_t bytes)237 static int ds1553_nvram_write(void *priv, unsigned int pos, void *val,
238 size_t bytes)
239 {
240 struct platform_device *pdev = priv;
241 struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
242 void __iomem *ioaddr = pdata->ioaddr;
243 u8 *buf = val;
244
245 for (; bytes; bytes--)
246 writeb(*buf++, ioaddr + pos++);
247 return 0;
248 }
249
ds1553_rtc_probe(struct platform_device * pdev)250 static int ds1553_rtc_probe(struct platform_device *pdev)
251 {
252 unsigned int cen, sec;
253 struct rtc_plat_data *pdata;
254 void __iomem *ioaddr;
255 int ret = 0;
256 struct nvmem_config nvmem_cfg = {
257 .name = "ds1553_nvram",
258 .word_size = 1,
259 .stride = 1,
260 .size = RTC_OFFSET,
261 .reg_read = ds1553_nvram_read,
262 .reg_write = ds1553_nvram_write,
263 .priv = pdev,
264 };
265
266 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
267 if (!pdata)
268 return -ENOMEM;
269
270 ioaddr = devm_platform_ioremap_resource(pdev, 0);
271 if (IS_ERR(ioaddr))
272 return PTR_ERR(ioaddr);
273 pdata->ioaddr = ioaddr;
274 pdata->irq = platform_get_irq(pdev, 0);
275
276 /* turn RTC on if it was not on */
277 sec = readb(ioaddr + RTC_SECONDS);
278 if (sec & RTC_STOP) {
279 sec &= RTC_SECONDS_MASK;
280 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
281 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
282 writeb(sec, ioaddr + RTC_SECONDS);
283 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
284 }
285 if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_BLF)
286 dev_warn(&pdev->dev, "voltage-low detected.\n");
287
288 spin_lock_init(&pdata->lock);
289 pdata->last_jiffies = jiffies;
290 platform_set_drvdata(pdev, pdata);
291
292 pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
293 if (IS_ERR(pdata->rtc))
294 return PTR_ERR(pdata->rtc);
295
296 pdata->rtc->ops = &ds1553_rtc_ops;
297
298 ret = devm_rtc_register_device(pdata->rtc);
299 if (ret)
300 return ret;
301
302 if (pdata->irq > 0) {
303 writeb(0, ioaddr + RTC_INTERRUPTS);
304 if (devm_request_irq(&pdev->dev, pdata->irq,
305 ds1553_rtc_interrupt,
306 0, pdev->name, pdev) < 0) {
307 dev_warn(&pdev->dev, "interrupt not available.\n");
308 pdata->irq = 0;
309 }
310 }
311
312 devm_rtc_nvmem_register(pdata->rtc, &nvmem_cfg);
313
314 return 0;
315 }
316
317 /* work with hotplug and coldplug */
318 MODULE_ALIAS("platform:rtc-ds1553");
319
320 static struct platform_driver ds1553_rtc_driver = {
321 .probe = ds1553_rtc_probe,
322 .driver = {
323 .name = "rtc-ds1553",
324 },
325 };
326
327 module_platform_driver(ds1553_rtc_driver);
328
329 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
330 MODULE_DESCRIPTION("Dallas DS1553 RTC driver");
331 MODULE_LICENSE("GPL");
332