1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * An rtc driver for the Dallas DS1511
4 *
5 * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
6 * Copyright (C) 2007 Andrew Sharp <andy.sharp@lsi.com>
7 *
8 * Real time clock driver for the Dallas 1511 chip, which also
9 * contains a watchdog timer.  There is a tiny amount of code that
10 * platform code could use to mess with the watchdog device a little
11 * bit, but not a full watchdog driver.
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/interrupt.h>
20#include <linux/rtc.h>
21#include <linux/platform_device.h>
22#include <linux/io.h>
23#include <linux/module.h>
24
25#define DS1511_SEC		0x0
26#define DS1511_MIN		0x1
27#define DS1511_HOUR		0x2
28#define DS1511_DOW		0x3
29#define DS1511_DOM		0x4
30#define DS1511_MONTH		0x5
31#define DS1511_YEAR		0x6
32#define DS1511_CENTURY		0x7
33#define DS1511_AM1_SEC		0x8
34#define DS1511_AM2_MIN		0x9
35#define DS1511_AM3_HOUR		0xa
36#define DS1511_AM4_DATE		0xb
37#define DS1511_WD_MSEC		0xc
38#define DS1511_WD_SEC		0xd
39#define DS1511_CONTROL_A	0xe
40#define DS1511_CONTROL_B	0xf
41#define DS1511_RAMADDR_LSB	0x10
42#define DS1511_RAMDATA		0x13
43
44#define DS1511_BLF1	0x80
45#define DS1511_BLF2	0x40
46#define DS1511_PRS	0x20
47#define DS1511_PAB	0x10
48#define DS1511_TDF	0x08
49#define DS1511_KSF	0x04
50#define DS1511_WDF	0x02
51#define DS1511_IRQF	0x01
52#define DS1511_TE	0x80
53#define DS1511_CS	0x40
54#define DS1511_BME	0x20
55#define DS1511_TPE	0x10
56#define DS1511_TIE	0x08
57#define DS1511_KIE	0x04
58#define DS1511_WDE	0x02
59#define DS1511_WDS	0x01
60#define DS1511_RAM_MAX	0x100
61
62struct ds1511_data {
63	struct rtc_device *rtc;
64	void __iomem *ioaddr;		/* virtual base address */
65	int irq;
66	spinlock_t lock;
67};
68
69static DEFINE_SPINLOCK(ds1511_lock);
70
71static __iomem char *ds1511_base;
72static u32 reg_spacing = 1;
73
74static void rtc_write(uint8_t val, uint32_t reg)
75{
76	writeb(val, ds1511_base + (reg * reg_spacing));
77}
78
79static uint8_t rtc_read(uint32_t reg)
80{
81	return readb(ds1511_base + (reg * reg_spacing));
82}
83
84static void rtc_disable_update(void)
85{
86	rtc_write((rtc_read(DS1511_CONTROL_B) & ~DS1511_TE), DS1511_CONTROL_B);
87}
88
89static void rtc_enable_update(void)
90{
91	rtc_write((rtc_read(DS1511_CONTROL_B) | DS1511_TE), DS1511_CONTROL_B);
92}
93
94static int ds1511_rtc_set_time(struct device *dev, struct rtc_time *rtc_tm)
95{
96	u8 mon, day, dow, hrs, min, sec, yrs, cen;
97	unsigned long flags;
98
99	yrs = rtc_tm->tm_year % 100;
100	cen = 19 + rtc_tm->tm_year / 100;
101	mon = rtc_tm->tm_mon + 1;   /* tm_mon starts at zero */
102	day = rtc_tm->tm_mday;
103	dow = rtc_tm->tm_wday & 0x7; /* automatic BCD */
104	hrs = rtc_tm->tm_hour;
105	min = rtc_tm->tm_min;
106	sec = rtc_tm->tm_sec;
107
108	/*
109	 * each register is a different number of valid bits
110	 */
111	sec = bin2bcd(sec) & 0x7f;
112	min = bin2bcd(min) & 0x7f;
113	hrs = bin2bcd(hrs) & 0x3f;
114	day = bin2bcd(day) & 0x3f;
115	mon = bin2bcd(mon) & 0x1f;
116	yrs = bin2bcd(yrs) & 0xff;
117	cen = bin2bcd(cen) & 0xff;
118
119	spin_lock_irqsave(&ds1511_lock, flags);
120	rtc_disable_update();
121	rtc_write(cen, DS1511_CENTURY);
122	rtc_write(yrs, DS1511_YEAR);
123	rtc_write((rtc_read(DS1511_MONTH) & 0xe0) | mon, DS1511_MONTH);
124	rtc_write(day, DS1511_DOM);
125	rtc_write(hrs, DS1511_HOUR);
126	rtc_write(min, DS1511_MIN);
127	rtc_write(sec, DS1511_SEC);
128	rtc_write(dow, DS1511_DOW);
129	rtc_enable_update();
130	spin_unlock_irqrestore(&ds1511_lock, flags);
131
132	return 0;
133}
134
135static int ds1511_rtc_read_time(struct device *dev, struct rtc_time *rtc_tm)
136{
137	unsigned int century;
138	unsigned long flags;
139
140	spin_lock_irqsave(&ds1511_lock, flags);
141	rtc_disable_update();
142
143	rtc_tm->tm_sec = rtc_read(DS1511_SEC) & 0x7f;
144	rtc_tm->tm_min = rtc_read(DS1511_MIN) & 0x7f;
145	rtc_tm->tm_hour = rtc_read(DS1511_HOUR) & 0x3f;
146	rtc_tm->tm_mday = rtc_read(DS1511_DOM) & 0x3f;
147	rtc_tm->tm_wday = rtc_read(DS1511_DOW) & 0x7;
148	rtc_tm->tm_mon = rtc_read(DS1511_MONTH) & 0x1f;
149	rtc_tm->tm_year = rtc_read(DS1511_YEAR) & 0x7f;
150	century = rtc_read(DS1511_CENTURY);
151
152	rtc_enable_update();
153	spin_unlock_irqrestore(&ds1511_lock, flags);
154
155	rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
156	rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
157	rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
158	rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
159	rtc_tm->tm_wday = bcd2bin(rtc_tm->tm_wday);
160	rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
161	rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
162	century = bcd2bin(century) * 100;
163
164	/*
165	 * Account for differences between how the RTC uses the values
166	 * and how they are defined in a struct rtc_time;
167	 */
168	century += rtc_tm->tm_year;
169	rtc_tm->tm_year = century - 1900;
170
171	rtc_tm->tm_mon--;
172
173	return 0;
174}
175
176static void ds1511_rtc_alarm_enable(unsigned int enabled)
177{
178	rtc_write(rtc_read(DS1511_CONTROL_B) | (enabled ? DS1511_TIE : 0), DS1511_CONTROL_B);
179}
180
181static int ds1511_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
182{
183	struct ds1511_data *ds1511 = dev_get_drvdata(dev);
184	unsigned long flags;
185
186	spin_lock_irqsave(&ds1511->lock, flags);
187	rtc_write(bin2bcd(alrm->time.tm_mday) & 0x3f, DS1511_AM4_DATE);
188	rtc_write(bin2bcd(alrm->time.tm_hour) & 0x3f, DS1511_AM3_HOUR);
189	rtc_write(bin2bcd(alrm->time.tm_min) & 0x7f, DS1511_AM2_MIN);
190	rtc_write(bin2bcd(alrm->time.tm_sec) & 0x7f, DS1511_AM1_SEC);
191	ds1511_rtc_alarm_enable(alrm->enabled);
192
193	rtc_read(DS1511_CONTROL_A);	/* clear interrupts */
194	spin_unlock_irqrestore(&ds1511->lock, flags);
195
196	return 0;
197}
198
199static int ds1511_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
200{
201	alrm->time.tm_mday = bcd2bin(rtc_read(DS1511_AM4_DATE) & 0x3f);
202	alrm->time.tm_hour = bcd2bin(rtc_read(DS1511_AM3_HOUR) & 0x3f);
203	alrm->time.tm_min = bcd2bin(rtc_read(DS1511_AM2_MIN) & 0x7f);
204	alrm->time.tm_sec = bcd2bin(rtc_read(DS1511_AM1_SEC) & 0x7f);
205	alrm->enabled = !!(rtc_read(DS1511_CONTROL_B) & DS1511_TIE);
206
207	return 0;
208}
209
210static irqreturn_t ds1511_interrupt(int irq, void *dev_id)
211{
212	struct platform_device *pdev = dev_id;
213	struct ds1511_data *ds1511 = platform_get_drvdata(pdev);
214	unsigned long events = 0;
215
216	spin_lock(&ds1511->lock);
217	/*
218	 * read and clear interrupt
219	 */
220	if (rtc_read(DS1511_CONTROL_A) & DS1511_IRQF) {
221		events = RTC_IRQF | RTC_AF;
222		rtc_update_irq(ds1511->rtc, 1, events);
223	}
224	spin_unlock(&ds1511->lock);
225	return events ? IRQ_HANDLED : IRQ_NONE;
226}
227
228static int ds1511_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
229{
230	struct ds1511_data *ds1511 = dev_get_drvdata(dev);
231	unsigned long flags;
232
233	spin_lock_irqsave(&ds1511->lock, flags);
234	ds1511_rtc_alarm_enable(enabled);
235	spin_unlock_irqrestore(&ds1511->lock, flags);
236
237	return 0;
238}
239
240static const struct rtc_class_ops ds1511_rtc_ops = {
241	.read_time		= ds1511_rtc_read_time,
242	.set_time		= ds1511_rtc_set_time,
243	.read_alarm		= ds1511_rtc_read_alarm,
244	.set_alarm		= ds1511_rtc_set_alarm,
245	.alarm_irq_enable	= ds1511_rtc_alarm_irq_enable,
246};
247
248static int ds1511_nvram_read(void *priv, unsigned int pos, void *buf,
249			     size_t size)
250{
251	int i;
252
253	rtc_write(pos, DS1511_RAMADDR_LSB);
254	for (i = 0; i < size; i++)
255		*(char *)buf++ = rtc_read(DS1511_RAMDATA);
256
257	return 0;
258}
259
260static int ds1511_nvram_write(void *priv, unsigned int pos, void *buf,
261			      size_t size)
262{
263	int i;
264
265	rtc_write(pos, DS1511_RAMADDR_LSB);
266	for (i = 0; i < size; i++)
267		rtc_write(*(char *)buf++, DS1511_RAMDATA);
268
269	return 0;
270}
271
272static int ds1511_rtc_probe(struct platform_device *pdev)
273{
274	struct ds1511_data *ds1511;
275	int ret = 0;
276	struct nvmem_config ds1511_nvmem_cfg = {
277		.name = "ds1511_nvram",
278		.word_size = 1,
279		.stride = 1,
280		.size = DS1511_RAM_MAX,
281		.reg_read = ds1511_nvram_read,
282		.reg_write = ds1511_nvram_write,
283		.priv = &pdev->dev,
284	};
285
286	ds1511 = devm_kzalloc(&pdev->dev, sizeof(*ds1511), GFP_KERNEL);
287	if (!ds1511)
288		return -ENOMEM;
289
290	ds1511_base = devm_platform_ioremap_resource(pdev, 0);
291	if (IS_ERR(ds1511_base))
292		return PTR_ERR(ds1511_base);
293	ds1511->ioaddr = ds1511_base;
294	ds1511->irq = platform_get_irq(pdev, 0);
295
296	/*
297	 * turn on the clock and the crystal, etc.
298	 */
299	rtc_write(DS1511_BME, DS1511_CONTROL_B);
300	rtc_write(0, DS1511_CONTROL_A);
301	/*
302	 * clear the wdog counter
303	 */
304	rtc_write(0, DS1511_WD_MSEC);
305	rtc_write(0, DS1511_WD_SEC);
306	/*
307	 * start the clock
308	 */
309	rtc_enable_update();
310
311	/*
312	 * check for a dying bat-tree
313	 */
314	if (rtc_read(DS1511_CONTROL_A) & DS1511_BLF1)
315		dev_warn(&pdev->dev, "voltage-low detected.\n");
316
317	spin_lock_init(&ds1511->lock);
318	platform_set_drvdata(pdev, ds1511);
319
320	ds1511->rtc = devm_rtc_allocate_device(&pdev->dev);
321	if (IS_ERR(ds1511->rtc))
322		return PTR_ERR(ds1511->rtc);
323
324	ds1511->rtc->ops = &ds1511_rtc_ops;
325	ds1511->rtc->range_max = RTC_TIMESTAMP_END_2099;
326	ds1511->rtc->alarm_offset_max = 28 * 24 * 60 * 60 - 1;
327
328	/*
329	 * if the platform has an interrupt in mind for this device,
330	 * then by all means, set it
331	 */
332	if (ds1511->irq > 0) {
333		rtc_read(DS1511_CONTROL_A);
334		if (devm_request_irq(&pdev->dev, ds1511->irq, ds1511_interrupt,
335			IRQF_SHARED, pdev->name, pdev) < 0) {
336
337			dev_warn(&pdev->dev, "interrupt not available.\n");
338			ds1511->irq = 0;
339		}
340	}
341
342	if (ds1511->irq == 0)
343		clear_bit(RTC_FEATURE_ALARM, ds1511->rtc->features);
344
345	ret = devm_rtc_register_device(ds1511->rtc);
346	if (ret)
347		return ret;
348
349	devm_rtc_nvmem_register(ds1511->rtc, &ds1511_nvmem_cfg);
350
351	return 0;
352}
353
354/* work with hotplug and coldplug */
355MODULE_ALIAS("platform:ds1511");
356
357static struct platform_driver ds1511_rtc_driver = {
358	.probe		= ds1511_rtc_probe,
359	.driver		= {
360		.name	= "ds1511",
361	},
362};
363
364module_platform_driver(ds1511_rtc_driver);
365
366MODULE_AUTHOR("Andrew Sharp <andy.sharp@lsi.com>");
367MODULE_DESCRIPTION("Dallas DS1511 RTC driver");
368MODULE_LICENSE("GPL");
369