1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Motorola CPCAP PMIC RTC driver
4 *
5 * Based on cpcap-regulator.c from Motorola Linux kernel tree
6 * Copyright (C) 2009 Motorola, Inc.
7 *
8 * Rewritten for mainline kernel
9 *  - use DT
10 *  - use regmap
11 *  - use standard interrupt framework
12 *  - use managed device resources
13 *  - remove custom "secure clock daemon" helpers
14 *
15 * Copyright (C) 2017 Sebastian Reichel <sre@kernel.org>
16 */
17#include <linux/kernel.h>
18#include <linux/module.h>
19#include <linux/mod_devicetable.h>
20#include <linux/init.h>
21#include <linux/device.h>
22#include <linux/platform_device.h>
23#include <linux/rtc.h>
24#include <linux/err.h>
25#include <linux/regmap.h>
26#include <linux/mfd/motorola-cpcap.h>
27#include <linux/slab.h>
28#include <linux/sched.h>
29
30#define SECS_PER_DAY 86400
31#define DAY_MASK  0x7FFF
32#define TOD1_MASK 0x00FF
33#define TOD2_MASK 0x01FF
34
35struct cpcap_time {
36	int day;
37	int tod1;
38	int tod2;
39};
40
41struct cpcap_rtc {
42	struct regmap *regmap;
43	struct rtc_device *rtc_dev;
44	u16 vendor;
45	int alarm_irq;
46	bool alarm_enabled;
47	int update_irq;
48	bool update_enabled;
49};
50
51static void cpcap2rtc_time(struct rtc_time *rtc, struct cpcap_time *cpcap)
52{
53	unsigned long int tod;
54	unsigned long int time;
55
56	tod = (cpcap->tod1 & TOD1_MASK) | ((cpcap->tod2 & TOD2_MASK) << 8);
57	time = tod + ((cpcap->day & DAY_MASK) * SECS_PER_DAY);
58
59	rtc_time64_to_tm(time, rtc);
60}
61
62static void rtc2cpcap_time(struct cpcap_time *cpcap, struct rtc_time *rtc)
63{
64	unsigned long time;
65
66	time = rtc_tm_to_time64(rtc);
67
68	cpcap->day = time / SECS_PER_DAY;
69	time %= SECS_PER_DAY;
70	cpcap->tod2 = (time >> 8) & TOD2_MASK;
71	cpcap->tod1 = time & TOD1_MASK;
72}
73
74static int cpcap_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
75{
76	struct cpcap_rtc *rtc = dev_get_drvdata(dev);
77
78	if (rtc->alarm_enabled == enabled)
79		return 0;
80
81	if (enabled)
82		enable_irq(rtc->alarm_irq);
83	else
84		disable_irq(rtc->alarm_irq);
85
86	rtc->alarm_enabled = !!enabled;
87
88	return 0;
89}
90
91static int cpcap_rtc_read_time(struct device *dev, struct rtc_time *tm)
92{
93	struct cpcap_rtc *rtc;
94	struct cpcap_time cpcap_tm;
95	int temp_tod2;
96	int ret;
97
98	rtc = dev_get_drvdata(dev);
99
100	ret = regmap_read(rtc->regmap, CPCAP_REG_TOD2, &temp_tod2);
101	ret |= regmap_read(rtc->regmap, CPCAP_REG_DAY, &cpcap_tm.day);
102	ret |= regmap_read(rtc->regmap, CPCAP_REG_TOD1, &cpcap_tm.tod1);
103	ret |= regmap_read(rtc->regmap, CPCAP_REG_TOD2, &cpcap_tm.tod2);
104
105	if (temp_tod2 > cpcap_tm.tod2)
106		ret |= regmap_read(rtc->regmap, CPCAP_REG_DAY, &cpcap_tm.day);
107
108	if (ret) {
109		dev_err(dev, "Failed to read time\n");
110		return -EIO;
111	}
112
113	cpcap2rtc_time(tm, &cpcap_tm);
114
115	return 0;
116}
117
118static int cpcap_rtc_set_time(struct device *dev, struct rtc_time *tm)
119{
120	struct cpcap_rtc *rtc;
121	struct cpcap_time cpcap_tm;
122	int ret = 0;
123
124	rtc = dev_get_drvdata(dev);
125
126	rtc2cpcap_time(&cpcap_tm, tm);
127
128	if (rtc->alarm_enabled)
129		disable_irq(rtc->alarm_irq);
130	if (rtc->update_enabled)
131		disable_irq(rtc->update_irq);
132
133	if (rtc->vendor == CPCAP_VENDOR_ST) {
134		/* The TOD1 and TOD2 registers MUST be written in this order
135		 * for the change to properly set.
136		 */
137		ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD1,
138					  TOD1_MASK, cpcap_tm.tod1);
139		ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD2,
140					  TOD2_MASK, cpcap_tm.tod2);
141		ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_DAY,
142					  DAY_MASK, cpcap_tm.day);
143	} else {
144		/* Clearing the upper lower 8 bits of the TOD guarantees that
145		 * the upper half of TOD (TOD2) will not increment for 0xFF RTC
146		 * ticks (255 seconds).  During this time we can safely write
147		 * to DAY, TOD2, then TOD1 (in that order) and expect RTC to be
148		 * synchronized to the exact time requested upon the final write
149		 * to TOD1.
150		 */
151		ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD1,
152					  TOD1_MASK, 0);
153		ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_DAY,
154					  DAY_MASK, cpcap_tm.day);
155		ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD2,
156					  TOD2_MASK, cpcap_tm.tod2);
157		ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD1,
158					  TOD1_MASK, cpcap_tm.tod1);
159	}
160
161	if (rtc->update_enabled)
162		enable_irq(rtc->update_irq);
163	if (rtc->alarm_enabled)
164		enable_irq(rtc->alarm_irq);
165
166	return ret;
167}
168
169static int cpcap_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
170{
171	struct cpcap_rtc *rtc;
172	struct cpcap_time cpcap_tm;
173	int ret;
174
175	rtc = dev_get_drvdata(dev);
176
177	alrm->enabled = rtc->alarm_enabled;
178
179	ret = regmap_read(rtc->regmap, CPCAP_REG_DAYA, &cpcap_tm.day);
180	ret |= regmap_read(rtc->regmap, CPCAP_REG_TODA2, &cpcap_tm.tod2);
181	ret |= regmap_read(rtc->regmap, CPCAP_REG_TODA1, &cpcap_tm.tod1);
182
183	if (ret) {
184		dev_err(dev, "Failed to read time\n");
185		return -EIO;
186	}
187
188	cpcap2rtc_time(&alrm->time, &cpcap_tm);
189	return rtc_valid_tm(&alrm->time);
190}
191
192static int cpcap_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
193{
194	struct cpcap_rtc *rtc;
195	struct cpcap_time cpcap_tm;
196	int ret;
197
198	rtc = dev_get_drvdata(dev);
199
200	rtc2cpcap_time(&cpcap_tm, &alrm->time);
201
202	if (rtc->alarm_enabled)
203		disable_irq(rtc->alarm_irq);
204
205	ret = regmap_update_bits(rtc->regmap, CPCAP_REG_DAYA, DAY_MASK,
206				 cpcap_tm.day);
207	ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TODA2, TOD2_MASK,
208				  cpcap_tm.tod2);
209	ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TODA1, TOD1_MASK,
210				  cpcap_tm.tod1);
211
212	if (!ret) {
213		enable_irq(rtc->alarm_irq);
214		rtc->alarm_enabled = true;
215	}
216
217	return ret;
218}
219
220static const struct rtc_class_ops cpcap_rtc_ops = {
221	.read_time		= cpcap_rtc_read_time,
222	.set_time		= cpcap_rtc_set_time,
223	.read_alarm		= cpcap_rtc_read_alarm,
224	.set_alarm		= cpcap_rtc_set_alarm,
225	.alarm_irq_enable	= cpcap_rtc_alarm_irq_enable,
226};
227
228static irqreturn_t cpcap_rtc_alarm_irq(int irq, void *data)
229{
230	struct cpcap_rtc *rtc = data;
231
232	rtc_update_irq(rtc->rtc_dev, 1, RTC_AF | RTC_IRQF);
233	return IRQ_HANDLED;
234}
235
236static irqreturn_t cpcap_rtc_update_irq(int irq, void *data)
237{
238	struct cpcap_rtc *rtc = data;
239
240	rtc_update_irq(rtc->rtc_dev, 1, RTC_UF | RTC_IRQF);
241	return IRQ_HANDLED;
242}
243
244static int cpcap_rtc_probe(struct platform_device *pdev)
245{
246	struct device *dev = &pdev->dev;
247	struct cpcap_rtc *rtc;
248	int err;
249
250	rtc = devm_kzalloc(dev, sizeof(*rtc), GFP_KERNEL);
251	if (!rtc)
252		return -ENOMEM;
253
254	rtc->regmap = dev_get_regmap(dev->parent, NULL);
255	if (!rtc->regmap)
256		return -ENODEV;
257
258	platform_set_drvdata(pdev, rtc);
259	rtc->rtc_dev = devm_rtc_allocate_device(dev);
260	if (IS_ERR(rtc->rtc_dev))
261		return PTR_ERR(rtc->rtc_dev);
262
263	rtc->rtc_dev->ops = &cpcap_rtc_ops;
264	rtc->rtc_dev->range_max = (timeu64_t) (DAY_MASK + 1) * SECS_PER_DAY - 1;
265
266	err = cpcap_get_vendor(dev, rtc->regmap, &rtc->vendor);
267	if (err)
268		return err;
269
270	rtc->alarm_irq = platform_get_irq(pdev, 0);
271	err = devm_request_threaded_irq(dev, rtc->alarm_irq, NULL,
272					cpcap_rtc_alarm_irq,
273					IRQF_TRIGGER_NONE | IRQF_ONESHOT,
274					"rtc_alarm", rtc);
275	if (err) {
276		dev_err(dev, "Could not request alarm irq: %d\n", err);
277		return err;
278	}
279	disable_irq(rtc->alarm_irq);
280
281	/* Stock Android uses the 1 Hz interrupt for "secure clock daemon",
282	 * which is not supported by the mainline kernel. The mainline kernel
283	 * does not use the irq at the moment, but we explicitly request and
284	 * disable it, so that its masked and does not wake up the processor
285	 * every second.
286	 */
287	rtc->update_irq = platform_get_irq(pdev, 1);
288	err = devm_request_threaded_irq(dev, rtc->update_irq, NULL,
289					cpcap_rtc_update_irq,
290					IRQF_TRIGGER_NONE | IRQF_ONESHOT,
291					"rtc_1hz", rtc);
292	if (err) {
293		dev_err(dev, "Could not request update irq: %d\n", err);
294		return err;
295	}
296	disable_irq(rtc->update_irq);
297
298	err = device_init_wakeup(dev, 1);
299	if (err) {
300		dev_err(dev, "wakeup initialization failed (%d)\n", err);
301		/* ignore error and continue without wakeup support */
302	}
303
304	return devm_rtc_register_device(rtc->rtc_dev);
305}
306
307static const struct of_device_id cpcap_rtc_of_match[] = {
308	{ .compatible = "motorola,cpcap-rtc", },
309	{},
310};
311MODULE_DEVICE_TABLE(of, cpcap_rtc_of_match);
312
313static struct platform_driver cpcap_rtc_driver = {
314	.probe		= cpcap_rtc_probe,
315	.driver		= {
316		.name	= "cpcap-rtc",
317		.of_match_table = cpcap_rtc_of_match,
318	},
319};
320
321module_platform_driver(cpcap_rtc_driver);
322
323MODULE_ALIAS("platform:cpcap-rtc");
324MODULE_DESCRIPTION("CPCAP RTC driver");
325MODULE_AUTHOR("Sebastian Reichel <sre@kernel.org>");
326MODULE_LICENSE("GPL");
327