1 /*
2 * A RTC driver for the Simtek STK17TA8
3 *
4 * By Thomas Hommel <thomas.hommel@ge.com>
5 *
6 * Based on the DS1553 driver from
7 * Atsushi Nemoto <anemo@mba.ocn.ne.jp>
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12 */
13
14 #include <linux/bcd.h>
15 #include <linux/init.h>
16 #include <linux/kernel.h>
17 #include <linux/gfp.h>
18 #include <linux/delay.h>
19 #include <linux/jiffies.h>
20 #include <linux/interrupt.h>
21 #include <linux/rtc.h>
22 #include <linux/platform_device.h>
23 #include <linux/io.h>
24 #include <linux/module.h>
25
26 #define RTC_REG_SIZE 0x20000
27 #define RTC_OFFSET 0x1fff0
28
29 #define RTC_FLAGS (RTC_OFFSET + 0)
30 #define RTC_CENTURY (RTC_OFFSET + 1)
31 #define RTC_SECONDS_ALARM (RTC_OFFSET + 2)
32 #define RTC_MINUTES_ALARM (RTC_OFFSET + 3)
33 #define RTC_HOURS_ALARM (RTC_OFFSET + 4)
34 #define RTC_DATE_ALARM (RTC_OFFSET + 5)
35 #define RTC_INTERRUPTS (RTC_OFFSET + 6)
36 #define RTC_WATCHDOG (RTC_OFFSET + 7)
37 #define RTC_CALIBRATION (RTC_OFFSET + 8)
38 #define RTC_SECONDS (RTC_OFFSET + 9)
39 #define RTC_MINUTES (RTC_OFFSET + 10)
40 #define RTC_HOURS (RTC_OFFSET + 11)
41 #define RTC_DAY (RTC_OFFSET + 12)
42 #define RTC_DATE (RTC_OFFSET + 13)
43 #define RTC_MONTH (RTC_OFFSET + 14)
44 #define RTC_YEAR (RTC_OFFSET + 15)
45
46 #define RTC_SECONDS_MASK 0x7f
47 #define RTC_DAY_MASK 0x07
48 #define RTC_CAL_MASK 0x3f
49
50 /* Bits in the Calibration register */
51 #define RTC_STOP 0x80
52
53 /* Bits in the Flags register */
54 #define RTC_FLAGS_AF 0x40
55 #define RTC_FLAGS_PF 0x20
56 #define RTC_WRITE 0x02
57 #define RTC_READ 0x01
58
59 /* Bits in the Interrupts register */
60 #define RTC_INTS_AIE 0x40
61
62 struct rtc_plat_data {
63 struct rtc_device *rtc;
64 void __iomem *ioaddr;
65 unsigned long last_jiffies;
66 int irq;
67 unsigned int irqen;
68 int alrm_sec;
69 int alrm_min;
70 int alrm_hour;
71 int alrm_mday;
72 spinlock_t lock;
73 };
74
stk17ta8_rtc_set_time(struct device * dev,struct rtc_time * tm)75 static int stk17ta8_rtc_set_time(struct device *dev, struct rtc_time *tm)
76 {
77 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
78 void __iomem *ioaddr = pdata->ioaddr;
79 u8 flags;
80
81 flags = readb(pdata->ioaddr + RTC_FLAGS);
82 writeb(flags | RTC_WRITE, pdata->ioaddr + RTC_FLAGS);
83
84 writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
85 writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
86 writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
87 writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
88 writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
89 writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
90 writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
91 writeb(bin2bcd((tm->tm_year + 1900) / 100), ioaddr + RTC_CENTURY);
92
93 writeb(flags & ~RTC_WRITE, pdata->ioaddr + RTC_FLAGS);
94 return 0;
95 }
96
stk17ta8_rtc_read_time(struct device * dev,struct rtc_time * tm)97 static int stk17ta8_rtc_read_time(struct device *dev, struct rtc_time *tm)
98 {
99 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
100 void __iomem *ioaddr = pdata->ioaddr;
101 unsigned int year, month, day, hour, minute, second, week;
102 unsigned int century;
103 u8 flags;
104
105 /* give enough time to update RTC in case of continuous read */
106 if (pdata->last_jiffies == jiffies)
107 msleep(1);
108 pdata->last_jiffies = jiffies;
109
110 flags = readb(pdata->ioaddr + RTC_FLAGS);
111 writeb(flags | RTC_READ, ioaddr + RTC_FLAGS);
112 second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
113 minute = readb(ioaddr + RTC_MINUTES);
114 hour = readb(ioaddr + RTC_HOURS);
115 day = readb(ioaddr + RTC_DATE);
116 week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
117 month = readb(ioaddr + RTC_MONTH);
118 year = readb(ioaddr + RTC_YEAR);
119 century = readb(ioaddr + RTC_CENTURY);
120 writeb(flags & ~RTC_READ, ioaddr + RTC_FLAGS);
121 tm->tm_sec = bcd2bin(second);
122 tm->tm_min = bcd2bin(minute);
123 tm->tm_hour = bcd2bin(hour);
124 tm->tm_mday = bcd2bin(day);
125 tm->tm_wday = bcd2bin(week);
126 tm->tm_mon = bcd2bin(month) - 1;
127 /* year is 1900 + tm->tm_year */
128 tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
129
130 return 0;
131 }
132
stk17ta8_rtc_update_alarm(struct rtc_plat_data * pdata)133 static void stk17ta8_rtc_update_alarm(struct rtc_plat_data *pdata)
134 {
135 void __iomem *ioaddr = pdata->ioaddr;
136 unsigned long irqflags;
137 u8 flags;
138
139 spin_lock_irqsave(&pdata->lock, irqflags);
140
141 flags = readb(ioaddr + RTC_FLAGS);
142 writeb(flags | RTC_WRITE, ioaddr + RTC_FLAGS);
143
144 writeb(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
145 0x80 : bin2bcd(pdata->alrm_mday),
146 ioaddr + RTC_DATE_ALARM);
147 writeb(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
148 0x80 : bin2bcd(pdata->alrm_hour),
149 ioaddr + RTC_HOURS_ALARM);
150 writeb(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
151 0x80 : bin2bcd(pdata->alrm_min),
152 ioaddr + RTC_MINUTES_ALARM);
153 writeb(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
154 0x80 : bin2bcd(pdata->alrm_sec),
155 ioaddr + RTC_SECONDS_ALARM);
156 writeb(pdata->irqen ? RTC_INTS_AIE : 0, ioaddr + RTC_INTERRUPTS);
157 readb(ioaddr + RTC_FLAGS); /* clear interrupts */
158 writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS);
159 spin_unlock_irqrestore(&pdata->lock, irqflags);
160 }
161
stk17ta8_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alrm)162 static int stk17ta8_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
163 {
164 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
165
166 if (pdata->irq <= 0)
167 return -EINVAL;
168 pdata->alrm_mday = alrm->time.tm_mday;
169 pdata->alrm_hour = alrm->time.tm_hour;
170 pdata->alrm_min = alrm->time.tm_min;
171 pdata->alrm_sec = alrm->time.tm_sec;
172 if (alrm->enabled)
173 pdata->irqen |= RTC_AF;
174 stk17ta8_rtc_update_alarm(pdata);
175 return 0;
176 }
177
stk17ta8_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alrm)178 static int stk17ta8_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
179 {
180 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
181
182 if (pdata->irq <= 0)
183 return -EINVAL;
184 alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
185 alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
186 alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
187 alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
188 alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
189 return 0;
190 }
191
stk17ta8_rtc_interrupt(int irq,void * dev_id)192 static irqreturn_t stk17ta8_rtc_interrupt(int irq, void *dev_id)
193 {
194 struct platform_device *pdev = dev_id;
195 struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
196 void __iomem *ioaddr = pdata->ioaddr;
197 unsigned long events = 0;
198
199 spin_lock(&pdata->lock);
200 /* read and clear interrupt */
201 if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_AF) {
202 events = RTC_IRQF;
203 if (readb(ioaddr + RTC_SECONDS_ALARM) & 0x80)
204 events |= RTC_UF;
205 else
206 events |= RTC_AF;
207 rtc_update_irq(pdata->rtc, 1, events);
208 }
209 spin_unlock(&pdata->lock);
210 return events ? IRQ_HANDLED : IRQ_NONE;
211 }
212
stk17ta8_rtc_alarm_irq_enable(struct device * dev,unsigned int enabled)213 static int stk17ta8_rtc_alarm_irq_enable(struct device *dev,
214 unsigned int enabled)
215 {
216 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
217
218 if (pdata->irq <= 0)
219 return -EINVAL;
220 if (enabled)
221 pdata->irqen |= RTC_AF;
222 else
223 pdata->irqen &= ~RTC_AF;
224 stk17ta8_rtc_update_alarm(pdata);
225 return 0;
226 }
227
228 static const struct rtc_class_ops stk17ta8_rtc_ops = {
229 .read_time = stk17ta8_rtc_read_time,
230 .set_time = stk17ta8_rtc_set_time,
231 .read_alarm = stk17ta8_rtc_read_alarm,
232 .set_alarm = stk17ta8_rtc_set_alarm,
233 .alarm_irq_enable = stk17ta8_rtc_alarm_irq_enable,
234 };
235
stk17ta8_nvram_read(void * priv,unsigned int pos,void * val,size_t bytes)236 static int stk17ta8_nvram_read(void *priv, unsigned int pos, void *val,
237 size_t bytes)
238 {
239 struct rtc_plat_data *pdata = priv;
240 void __iomem *ioaddr = pdata->ioaddr;
241 u8 *buf = val;
242
243 for (; bytes; bytes--)
244 *buf++ = readb(ioaddr + pos++);
245 return 0;
246 }
247
stk17ta8_nvram_write(void * priv,unsigned int pos,void * val,size_t bytes)248 static int stk17ta8_nvram_write(void *priv, unsigned int pos, void *val,
249 size_t bytes)
250 {
251 struct rtc_plat_data *pdata = priv;
252 void __iomem *ioaddr = pdata->ioaddr;
253 u8 *buf = val;
254
255 for (; bytes; bytes--)
256 writeb(*buf++, ioaddr + pos++);
257 return 0;
258 }
259
stk17ta8_rtc_probe(struct platform_device * pdev)260 static int stk17ta8_rtc_probe(struct platform_device *pdev)
261 {
262 struct resource *res;
263 unsigned int cal;
264 unsigned int flags;
265 struct rtc_plat_data *pdata;
266 void __iomem *ioaddr;
267 int ret = 0;
268 struct nvmem_config nvmem_cfg = {
269 .name = "stk17ta8_nvram",
270 .word_size = 1,
271 .stride = 1,
272 .size = RTC_OFFSET,
273 .reg_read = stk17ta8_nvram_read,
274 .reg_write = stk17ta8_nvram_write,
275 };
276
277 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
278 if (!pdata)
279 return -ENOMEM;
280
281 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
282 ioaddr = devm_ioremap_resource(&pdev->dev, res);
283 if (IS_ERR(ioaddr))
284 return PTR_ERR(ioaddr);
285 pdata->ioaddr = ioaddr;
286 pdata->irq = platform_get_irq(pdev, 0);
287
288 /* turn RTC on if it was not on */
289 cal = readb(ioaddr + RTC_CALIBRATION);
290 if (cal & RTC_STOP) {
291 cal &= RTC_CAL_MASK;
292 flags = readb(ioaddr + RTC_FLAGS);
293 writeb(flags | RTC_WRITE, ioaddr + RTC_FLAGS);
294 writeb(cal, ioaddr + RTC_CALIBRATION);
295 writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS);
296 }
297 if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_PF)
298 dev_warn(&pdev->dev, "voltage-low detected.\n");
299
300 spin_lock_init(&pdata->lock);
301 pdata->last_jiffies = jiffies;
302 platform_set_drvdata(pdev, pdata);
303 if (pdata->irq > 0) {
304 writeb(0, ioaddr + RTC_INTERRUPTS);
305 if (devm_request_irq(&pdev->dev, pdata->irq,
306 stk17ta8_rtc_interrupt,
307 IRQF_SHARED,
308 pdev->name, pdev) < 0) {
309 dev_warn(&pdev->dev, "interrupt not available.\n");
310 pdata->irq = 0;
311 }
312 }
313
314 pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
315 if (IS_ERR(pdata->rtc))
316 return PTR_ERR(pdata->rtc);
317
318 pdata->rtc->ops = &stk17ta8_rtc_ops;
319 pdata->rtc->nvram_old_abi = true;
320
321 nvmem_cfg.priv = pdata;
322 ret = rtc_nvmem_register(pdata->rtc, &nvmem_cfg);
323 if (ret)
324 return ret;
325
326 return rtc_register_device(pdata->rtc);
327 }
328
329 /* work with hotplug and coldplug */
330 MODULE_ALIAS("platform:stk17ta8");
331
332 static struct platform_driver stk17ta8_rtc_driver = {
333 .probe = stk17ta8_rtc_probe,
334 .driver = {
335 .name = "stk17ta8",
336 },
337 };
338
339 module_platform_driver(stk17ta8_rtc_driver);
340
341 MODULE_AUTHOR("Thomas Hommel <thomas.hommel@ge.com>");
342 MODULE_DESCRIPTION("Simtek STK17TA8 RTC driver");
343 MODULE_LICENSE("GPL");
344