1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * A RTC driver for the Simtek STK17TA8 |
4 | * |
5 | * By Thomas Hommel <thomas.hommel@ge.com> |
6 | * |
7 | * Based on the DS1553 driver from |
8 | * Atsushi Nemoto <anemo@mba.ocn.ne.jp> |
9 | */ |
10 | |
11 | #include <linux/bcd.h> |
12 | #include <linux/init.h> |
13 | #include <linux/kernel.h> |
14 | #include <linux/gfp.h> |
15 | #include <linux/delay.h> |
16 | #include <linux/jiffies.h> |
17 | #include <linux/interrupt.h> |
18 | #include <linux/rtc.h> |
19 | #include <linux/platform_device.h> |
20 | #include <linux/io.h> |
21 | #include <linux/module.h> |
22 | |
23 | #define RTC_REG_SIZE 0x20000 |
24 | #define RTC_OFFSET 0x1fff0 |
25 | |
26 | #define RTC_FLAGS (RTC_OFFSET + 0) |
27 | #define RTC_CENTURY (RTC_OFFSET + 1) |
28 | #define RTC_SECONDS_ALARM (RTC_OFFSET + 2) |
29 | #define RTC_MINUTES_ALARM (RTC_OFFSET + 3) |
30 | #define RTC_HOURS_ALARM (RTC_OFFSET + 4) |
31 | #define RTC_DATE_ALARM (RTC_OFFSET + 5) |
32 | #define RTC_INTERRUPTS (RTC_OFFSET + 6) |
33 | #define RTC_WATCHDOG (RTC_OFFSET + 7) |
34 | #define RTC_CALIBRATION (RTC_OFFSET + 8) |
35 | #define RTC_SECONDS (RTC_OFFSET + 9) |
36 | #define RTC_MINUTES (RTC_OFFSET + 10) |
37 | #define RTC_HOURS (RTC_OFFSET + 11) |
38 | #define RTC_DAY (RTC_OFFSET + 12) |
39 | #define RTC_DATE (RTC_OFFSET + 13) |
40 | #define RTC_MONTH (RTC_OFFSET + 14) |
41 | #define RTC_YEAR (RTC_OFFSET + 15) |
42 | |
43 | #define RTC_SECONDS_MASK 0x7f |
44 | #define RTC_DAY_MASK 0x07 |
45 | #define RTC_CAL_MASK 0x3f |
46 | |
47 | /* Bits in the Calibration register */ |
48 | #define RTC_STOP 0x80 |
49 | |
50 | /* Bits in the Flags register */ |
51 | #define RTC_FLAGS_AF 0x40 |
52 | #define RTC_FLAGS_PF 0x20 |
53 | #define RTC_WRITE 0x02 |
54 | #define RTC_READ 0x01 |
55 | |
56 | /* Bits in the Interrupts register */ |
57 | #define RTC_INTS_AIE 0x40 |
58 | |
59 | struct rtc_plat_data { |
60 | struct rtc_device *rtc; |
61 | void __iomem *ioaddr; |
62 | unsigned long last_jiffies; |
63 | int irq; |
64 | unsigned int irqen; |
65 | int alrm_sec; |
66 | int alrm_min; |
67 | int alrm_hour; |
68 | int alrm_mday; |
69 | spinlock_t lock; |
70 | }; |
71 | |
72 | static int stk17ta8_rtc_set_time(struct device *dev, struct rtc_time *tm) |
73 | { |
74 | struct rtc_plat_data *pdata = dev_get_drvdata(dev); |
75 | void __iomem *ioaddr = pdata->ioaddr; |
76 | u8 flags; |
77 | |
78 | flags = readb(addr: pdata->ioaddr + RTC_FLAGS); |
79 | writeb(val: flags | RTC_WRITE, addr: pdata->ioaddr + RTC_FLAGS); |
80 | |
81 | writeb(bin2bcd(tm->tm_year % 100), addr: ioaddr + RTC_YEAR); |
82 | writeb(bin2bcd(tm->tm_mon + 1), addr: ioaddr + RTC_MONTH); |
83 | writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, addr: ioaddr + RTC_DAY); |
84 | writeb(bin2bcd(tm->tm_mday), addr: ioaddr + RTC_DATE); |
85 | writeb(bin2bcd(tm->tm_hour), addr: ioaddr + RTC_HOURS); |
86 | writeb(bin2bcd(tm->tm_min), addr: ioaddr + RTC_MINUTES); |
87 | writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, addr: ioaddr + RTC_SECONDS); |
88 | writeb(bin2bcd((tm->tm_year + 1900) / 100), addr: ioaddr + RTC_CENTURY); |
89 | |
90 | writeb(val: flags & ~RTC_WRITE, addr: pdata->ioaddr + RTC_FLAGS); |
91 | return 0; |
92 | } |
93 | |
94 | static int stk17ta8_rtc_read_time(struct device *dev, struct rtc_time *tm) |
95 | { |
96 | struct rtc_plat_data *pdata = dev_get_drvdata(dev); |
97 | void __iomem *ioaddr = pdata->ioaddr; |
98 | unsigned int year, month, day, hour, minute, second, week; |
99 | unsigned int century; |
100 | u8 flags; |
101 | |
102 | /* give enough time to update RTC in case of continuous read */ |
103 | if (pdata->last_jiffies == jiffies) |
104 | msleep(msecs: 1); |
105 | pdata->last_jiffies = jiffies; |
106 | |
107 | flags = readb(addr: pdata->ioaddr + RTC_FLAGS); |
108 | writeb(val: flags | RTC_READ, addr: ioaddr + RTC_FLAGS); |
109 | second = readb(addr: ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK; |
110 | minute = readb(addr: ioaddr + RTC_MINUTES); |
111 | hour = readb(addr: ioaddr + RTC_HOURS); |
112 | day = readb(addr: ioaddr + RTC_DATE); |
113 | week = readb(addr: ioaddr + RTC_DAY) & RTC_DAY_MASK; |
114 | month = readb(addr: ioaddr + RTC_MONTH); |
115 | year = readb(addr: ioaddr + RTC_YEAR); |
116 | century = readb(addr: ioaddr + RTC_CENTURY); |
117 | writeb(val: flags & ~RTC_READ, addr: ioaddr + RTC_FLAGS); |
118 | tm->tm_sec = bcd2bin(second); |
119 | tm->tm_min = bcd2bin(minute); |
120 | tm->tm_hour = bcd2bin(hour); |
121 | tm->tm_mday = bcd2bin(day); |
122 | tm->tm_wday = bcd2bin(week); |
123 | tm->tm_mon = bcd2bin(month) - 1; |
124 | /* year is 1900 + tm->tm_year */ |
125 | tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900; |
126 | |
127 | return 0; |
128 | } |
129 | |
130 | static void stk17ta8_rtc_update_alarm(struct rtc_plat_data *pdata) |
131 | { |
132 | void __iomem *ioaddr = pdata->ioaddr; |
133 | unsigned long irqflags; |
134 | u8 flags; |
135 | |
136 | spin_lock_irqsave(&pdata->lock, irqflags); |
137 | |
138 | flags = readb(addr: ioaddr + RTC_FLAGS); |
139 | writeb(val: flags | RTC_WRITE, addr: ioaddr + RTC_FLAGS); |
140 | |
141 | writeb(val: pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ? |
142 | 0x80 : bin2bcd(pdata->alrm_mday), |
143 | addr: ioaddr + RTC_DATE_ALARM); |
144 | writeb(val: pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ? |
145 | 0x80 : bin2bcd(pdata->alrm_hour), |
146 | addr: ioaddr + RTC_HOURS_ALARM); |
147 | writeb(val: pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ? |
148 | 0x80 : bin2bcd(pdata->alrm_min), |
149 | addr: ioaddr + RTC_MINUTES_ALARM); |
150 | writeb(val: pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ? |
151 | 0x80 : bin2bcd(pdata->alrm_sec), |
152 | addr: ioaddr + RTC_SECONDS_ALARM); |
153 | writeb(val: pdata->irqen ? RTC_INTS_AIE : 0, addr: ioaddr + RTC_INTERRUPTS); |
154 | readb(addr: ioaddr + RTC_FLAGS); /* clear interrupts */ |
155 | writeb(val: flags & ~RTC_WRITE, addr: ioaddr + RTC_FLAGS); |
156 | spin_unlock_irqrestore(lock: &pdata->lock, flags: irqflags); |
157 | } |
158 | |
159 | static int stk17ta8_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm) |
160 | { |
161 | struct rtc_plat_data *pdata = dev_get_drvdata(dev); |
162 | |
163 | if (pdata->irq <= 0) |
164 | return -EINVAL; |
165 | pdata->alrm_mday = alrm->time.tm_mday; |
166 | pdata->alrm_hour = alrm->time.tm_hour; |
167 | pdata->alrm_min = alrm->time.tm_min; |
168 | pdata->alrm_sec = alrm->time.tm_sec; |
169 | if (alrm->enabled) |
170 | pdata->irqen |= RTC_AF; |
171 | stk17ta8_rtc_update_alarm(pdata); |
172 | return 0; |
173 | } |
174 | |
175 | static int stk17ta8_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm) |
176 | { |
177 | struct rtc_plat_data *pdata = dev_get_drvdata(dev); |
178 | |
179 | if (pdata->irq <= 0) |
180 | return -EINVAL; |
181 | alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday; |
182 | alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour; |
183 | alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min; |
184 | alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec; |
185 | alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0; |
186 | return 0; |
187 | } |
188 | |
189 | static irqreturn_t stk17ta8_rtc_interrupt(int irq, void *dev_id) |
190 | { |
191 | struct platform_device *pdev = dev_id; |
192 | struct rtc_plat_data *pdata = platform_get_drvdata(pdev); |
193 | void __iomem *ioaddr = pdata->ioaddr; |
194 | unsigned long events = 0; |
195 | |
196 | spin_lock(lock: &pdata->lock); |
197 | /* read and clear interrupt */ |
198 | if (readb(addr: ioaddr + RTC_FLAGS) & RTC_FLAGS_AF) { |
199 | events = RTC_IRQF; |
200 | if (readb(addr: ioaddr + RTC_SECONDS_ALARM) & 0x80) |
201 | events |= RTC_UF; |
202 | else |
203 | events |= RTC_AF; |
204 | rtc_update_irq(rtc: pdata->rtc, num: 1, events); |
205 | } |
206 | spin_unlock(lock: &pdata->lock); |
207 | return events ? IRQ_HANDLED : IRQ_NONE; |
208 | } |
209 | |
210 | static int stk17ta8_rtc_alarm_irq_enable(struct device *dev, |
211 | unsigned int enabled) |
212 | { |
213 | struct rtc_plat_data *pdata = dev_get_drvdata(dev); |
214 | |
215 | if (pdata->irq <= 0) |
216 | return -EINVAL; |
217 | if (enabled) |
218 | pdata->irqen |= RTC_AF; |
219 | else |
220 | pdata->irqen &= ~RTC_AF; |
221 | stk17ta8_rtc_update_alarm(pdata); |
222 | return 0; |
223 | } |
224 | |
225 | static const struct rtc_class_ops stk17ta8_rtc_ops = { |
226 | .read_time = stk17ta8_rtc_read_time, |
227 | .set_time = stk17ta8_rtc_set_time, |
228 | .read_alarm = stk17ta8_rtc_read_alarm, |
229 | .set_alarm = stk17ta8_rtc_set_alarm, |
230 | .alarm_irq_enable = stk17ta8_rtc_alarm_irq_enable, |
231 | }; |
232 | |
233 | static int stk17ta8_nvram_read(void *priv, unsigned int pos, void *val, |
234 | size_t bytes) |
235 | { |
236 | struct rtc_plat_data *pdata = priv; |
237 | void __iomem *ioaddr = pdata->ioaddr; |
238 | u8 *buf = val; |
239 | |
240 | for (; bytes; bytes--) |
241 | *buf++ = readb(addr: ioaddr + pos++); |
242 | return 0; |
243 | } |
244 | |
245 | static int stk17ta8_nvram_write(void *priv, unsigned int pos, void *val, |
246 | size_t bytes) |
247 | { |
248 | struct rtc_plat_data *pdata = priv; |
249 | void __iomem *ioaddr = pdata->ioaddr; |
250 | u8 *buf = val; |
251 | |
252 | for (; bytes; bytes--) |
253 | writeb(val: *buf++, addr: ioaddr + pos++); |
254 | return 0; |
255 | } |
256 | |
257 | static int stk17ta8_rtc_probe(struct platform_device *pdev) |
258 | { |
259 | unsigned int cal; |
260 | unsigned int flags; |
261 | struct rtc_plat_data *pdata; |
262 | void __iomem *ioaddr; |
263 | int ret = 0; |
264 | struct nvmem_config nvmem_cfg = { |
265 | .name = "stk17ta8_nvram" , |
266 | .word_size = 1, |
267 | .stride = 1, |
268 | .size = RTC_OFFSET, |
269 | .reg_read = stk17ta8_nvram_read, |
270 | .reg_write = stk17ta8_nvram_write, |
271 | }; |
272 | |
273 | pdata = devm_kzalloc(dev: &pdev->dev, size: sizeof(*pdata), GFP_KERNEL); |
274 | if (!pdata) |
275 | return -ENOMEM; |
276 | |
277 | ioaddr = devm_platform_ioremap_resource(pdev, index: 0); |
278 | if (IS_ERR(ptr: ioaddr)) |
279 | return PTR_ERR(ptr: ioaddr); |
280 | pdata->ioaddr = ioaddr; |
281 | pdata->irq = platform_get_irq(pdev, 0); |
282 | |
283 | /* turn RTC on if it was not on */ |
284 | cal = readb(addr: ioaddr + RTC_CALIBRATION); |
285 | if (cal & RTC_STOP) { |
286 | cal &= RTC_CAL_MASK; |
287 | flags = readb(addr: ioaddr + RTC_FLAGS); |
288 | writeb(val: flags | RTC_WRITE, addr: ioaddr + RTC_FLAGS); |
289 | writeb(val: cal, addr: ioaddr + RTC_CALIBRATION); |
290 | writeb(val: flags & ~RTC_WRITE, addr: ioaddr + RTC_FLAGS); |
291 | } |
292 | if (readb(addr: ioaddr + RTC_FLAGS) & RTC_FLAGS_PF) |
293 | dev_warn(&pdev->dev, "voltage-low detected.\n" ); |
294 | |
295 | spin_lock_init(&pdata->lock); |
296 | pdata->last_jiffies = jiffies; |
297 | platform_set_drvdata(pdev, data: pdata); |
298 | if (pdata->irq > 0) { |
299 | writeb(val: 0, addr: ioaddr + RTC_INTERRUPTS); |
300 | if (devm_request_irq(dev: &pdev->dev, irq: pdata->irq, |
301 | handler: stk17ta8_rtc_interrupt, |
302 | IRQF_SHARED, |
303 | devname: pdev->name, dev_id: pdev) < 0) { |
304 | dev_warn(&pdev->dev, "interrupt not available.\n" ); |
305 | pdata->irq = 0; |
306 | } |
307 | } |
308 | |
309 | pdata->rtc = devm_rtc_allocate_device(dev: &pdev->dev); |
310 | if (IS_ERR(ptr: pdata->rtc)) |
311 | return PTR_ERR(ptr: pdata->rtc); |
312 | |
313 | pdata->rtc->ops = &stk17ta8_rtc_ops; |
314 | |
315 | nvmem_cfg.priv = pdata; |
316 | ret = devm_rtc_nvmem_register(rtc: pdata->rtc, nvmem_config: &nvmem_cfg); |
317 | if (ret) |
318 | return ret; |
319 | |
320 | return devm_rtc_register_device(pdata->rtc); |
321 | } |
322 | |
323 | /* work with hotplug and coldplug */ |
324 | MODULE_ALIAS("platform:stk17ta8" ); |
325 | |
326 | static struct platform_driver stk17ta8_rtc_driver = { |
327 | .probe = stk17ta8_rtc_probe, |
328 | .driver = { |
329 | .name = "stk17ta8" , |
330 | }, |
331 | }; |
332 | |
333 | module_platform_driver(stk17ta8_rtc_driver); |
334 | |
335 | MODULE_AUTHOR("Thomas Hommel <thomas.hommel@ge.com>" ); |
336 | MODULE_DESCRIPTION("Simtek STK17TA8 RTC driver" ); |
337 | MODULE_LICENSE("GPL" ); |
338 | |