1// SPDX-License-Identifier: GPL-2.0
2/*
3 * MOXA ART RTC driver.
4 *
5 * Copyright (C) 2013 Jonas Jensen
6 *
7 * Jonas Jensen <jonas.jensen@gmail.com>
8 *
9 * Based on code from
10 * Moxa Technology Co., Ltd. <www.moxa.com>
11 */
12
13#include <linux/err.h>
14#include <linux/init.h>
15#include <linux/kernel.h>
16#include <linux/delay.h>
17#include <linux/rtc.h>
18#include <linux/platform_device.h>
19#include <linux/module.h>
20#include <linux/mod_devicetable.h>
21#include <linux/gpio/consumer.h>
22
23#define GPIO_RTC_RESERVED			0x0C
24#define GPIO_RTC_DATA_SET			0x10
25#define GPIO_RTC_DATA_CLEAR			0x14
26#define GPIO_RTC_PIN_PULL_ENABLE		0x18
27#define GPIO_RTC_PIN_PULL_TYPE			0x1C
28#define GPIO_RTC_INT_ENABLE			0x20
29#define GPIO_RTC_INT_RAW_STATE			0x24
30#define GPIO_RTC_INT_MASKED_STATE		0x28
31#define GPIO_RTC_INT_MASK			0x2C
32#define GPIO_RTC_INT_CLEAR			0x30
33#define GPIO_RTC_INT_TRIGGER			0x34
34#define GPIO_RTC_INT_BOTH			0x38
35#define GPIO_RTC_INT_RISE_NEG			0x3C
36#define GPIO_RTC_BOUNCE_ENABLE			0x40
37#define GPIO_RTC_BOUNCE_PRE_SCALE		0x44
38#define GPIO_RTC_PROTECT_W			0x8E
39#define GPIO_RTC_PROTECT_R			0x8F
40#define GPIO_RTC_YEAR_W				0x8C
41#define GPIO_RTC_YEAR_R				0x8D
42#define GPIO_RTC_DAY_W				0x8A
43#define GPIO_RTC_DAY_R				0x8B
44#define GPIO_RTC_MONTH_W			0x88
45#define GPIO_RTC_MONTH_R			0x89
46#define GPIO_RTC_DATE_W				0x86
47#define GPIO_RTC_DATE_R				0x87
48#define GPIO_RTC_HOURS_W			0x84
49#define GPIO_RTC_HOURS_R			0x85
50#define GPIO_RTC_MINUTES_W			0x82
51#define GPIO_RTC_MINUTES_R			0x83
52#define GPIO_RTC_SECONDS_W			0x80
53#define GPIO_RTC_SECONDS_R			0x81
54#define GPIO_RTC_DELAY_TIME			8
55
56struct moxart_rtc {
57	struct rtc_device *rtc;
58	spinlock_t rtc_lock;
59	struct gpio_desc *gpio_data;
60	struct gpio_desc *gpio_sclk;
61	struct gpio_desc *gpio_reset;
62};
63
64static int day_of_year[12] =	{ 0, 31, 59, 90, 120, 151, 181,
65				  212, 243, 273, 304, 334 };
66
67static void moxart_rtc_write_byte(struct device *dev, u8 data)
68{
69	struct moxart_rtc *moxart_rtc = dev_get_drvdata(dev);
70	int i;
71
72	for (i = 0; i < 8; i++, data >>= 1) {
73		gpiod_set_value(moxart_rtc->gpio_sclk, 0);
74		gpiod_set_value(moxart_rtc->gpio_data, ((data & 1) == 1));
75		udelay(GPIO_RTC_DELAY_TIME);
76		gpiod_set_value(moxart_rtc->gpio_sclk, 1);
77		udelay(GPIO_RTC_DELAY_TIME);
78	}
79}
80
81static u8 moxart_rtc_read_byte(struct device *dev)
82{
83	struct moxart_rtc *moxart_rtc = dev_get_drvdata(dev);
84	int i;
85	u8 data = 0;
86
87	for (i = 0; i < 8; i++) {
88		gpiod_set_value(moxart_rtc->gpio_sclk, 0);
89		udelay(GPIO_RTC_DELAY_TIME);
90		gpiod_set_value(moxart_rtc->gpio_sclk, 1);
91		udelay(GPIO_RTC_DELAY_TIME);
92		if (gpiod_get_value(moxart_rtc->gpio_data))
93			data |= (1 << i);
94		udelay(GPIO_RTC_DELAY_TIME);
95	}
96	return data;
97}
98
99static u8 moxart_rtc_read_register(struct device *dev, u8 cmd)
100{
101	struct moxart_rtc *moxart_rtc = dev_get_drvdata(dev);
102	u8 data;
103	unsigned long flags;
104
105	local_irq_save(flags);
106
107	gpiod_direction_output(moxart_rtc->gpio_data, 0);
108	gpiod_set_value(moxart_rtc->gpio_reset, 1);
109	udelay(GPIO_RTC_DELAY_TIME);
110	moxart_rtc_write_byte(dev, cmd);
111	gpiod_direction_input(moxart_rtc->gpio_data);
112	udelay(GPIO_RTC_DELAY_TIME);
113	data = moxart_rtc_read_byte(dev);
114	gpiod_set_value(moxart_rtc->gpio_sclk, 0);
115	gpiod_set_value(moxart_rtc->gpio_reset, 0);
116	udelay(GPIO_RTC_DELAY_TIME);
117
118	local_irq_restore(flags);
119
120	return data;
121}
122
123static void moxart_rtc_write_register(struct device *dev, u8 cmd, u8 data)
124{
125	struct moxart_rtc *moxart_rtc = dev_get_drvdata(dev);
126	unsigned long flags;
127
128	local_irq_save(flags);
129
130	gpiod_direction_output(moxart_rtc->gpio_data, 0);
131	gpiod_set_value(moxart_rtc->gpio_reset, 1);
132	udelay(GPIO_RTC_DELAY_TIME);
133	moxart_rtc_write_byte(dev, cmd);
134	moxart_rtc_write_byte(dev, data);
135	gpiod_set_value(moxart_rtc->gpio_sclk, 0);
136	gpiod_set_value(moxart_rtc->gpio_reset, 0);
137	udelay(GPIO_RTC_DELAY_TIME);
138
139	local_irq_restore(flags);
140}
141
142static int moxart_rtc_set_time(struct device *dev, struct rtc_time *tm)
143{
144	struct moxart_rtc *moxart_rtc = dev_get_drvdata(dev);
145
146	spin_lock_irq(&moxart_rtc->rtc_lock);
147
148	moxart_rtc_write_register(dev, GPIO_RTC_PROTECT_W, 0);
149	moxart_rtc_write_register(dev, GPIO_RTC_YEAR_W,
150				  (((tm->tm_year - 100) / 10) << 4) |
151				  ((tm->tm_year - 100) % 10));
152
153	moxart_rtc_write_register(dev, GPIO_RTC_MONTH_W,
154				  (((tm->tm_mon + 1) / 10) << 4) |
155				  ((tm->tm_mon + 1) % 10));
156
157	moxart_rtc_write_register(dev, GPIO_RTC_DATE_W,
158				  ((tm->tm_mday / 10) << 4) |
159				  (tm->tm_mday % 10));
160
161	moxart_rtc_write_register(dev, GPIO_RTC_HOURS_W,
162				  ((tm->tm_hour / 10) << 4) |
163				  (tm->tm_hour % 10));
164
165	moxart_rtc_write_register(dev, GPIO_RTC_MINUTES_W,
166				  ((tm->tm_min / 10) << 4) |
167				  (tm->tm_min % 10));
168
169	moxart_rtc_write_register(dev, GPIO_RTC_SECONDS_W,
170				  ((tm->tm_sec / 10) << 4) |
171				  (tm->tm_sec % 10));
172
173	moxart_rtc_write_register(dev, GPIO_RTC_PROTECT_W, 0x80);
174
175	spin_unlock_irq(&moxart_rtc->rtc_lock);
176
177	dev_dbg(dev, "%s: success tm_year=%d tm_mon=%d\n"
178		"tm_mday=%d tm_hour=%d tm_min=%d tm_sec=%d\n",
179		__func__, tm->tm_year, tm->tm_mon, tm->tm_mday,
180		tm->tm_hour, tm->tm_min, tm->tm_sec);
181
182	return 0;
183}
184
185static int moxart_rtc_read_time(struct device *dev, struct rtc_time *tm)
186{
187	struct moxart_rtc *moxart_rtc = dev_get_drvdata(dev);
188	unsigned char v;
189
190	spin_lock_irq(&moxart_rtc->rtc_lock);
191
192	v = moxart_rtc_read_register(dev, GPIO_RTC_SECONDS_R);
193	tm->tm_sec = (((v & 0x70) >> 4) * 10) + (v & 0x0F);
194
195	v = moxart_rtc_read_register(dev, GPIO_RTC_MINUTES_R);
196	tm->tm_min = (((v & 0x70) >> 4) * 10) + (v & 0x0F);
197
198	v = moxart_rtc_read_register(dev, GPIO_RTC_HOURS_R);
199	if (v & 0x80) { /* 12-hour mode */
200		tm->tm_hour = (((v & 0x10) >> 4) * 10) + (v & 0x0F);
201		if (v & 0x20) { /* PM mode */
202			tm->tm_hour += 12;
203			if (tm->tm_hour >= 24)
204				tm->tm_hour = 0;
205		}
206	} else { /* 24-hour mode */
207		tm->tm_hour = (((v & 0x30) >> 4) * 10) + (v & 0x0F);
208	}
209
210	v = moxart_rtc_read_register(dev, GPIO_RTC_DATE_R);
211	tm->tm_mday = (((v & 0x30) >> 4) * 10) + (v & 0x0F);
212
213	v = moxart_rtc_read_register(dev, GPIO_RTC_MONTH_R);
214	tm->tm_mon = (((v & 0x10) >> 4) * 10) + (v & 0x0F);
215	tm->tm_mon--;
216
217	v = moxart_rtc_read_register(dev, GPIO_RTC_YEAR_R);
218	tm->tm_year = (((v & 0xF0) >> 4) * 10) + (v & 0x0F);
219	tm->tm_year += 100;
220	if (tm->tm_year <= 69)
221		tm->tm_year += 100;
222
223	v = moxart_rtc_read_register(dev, GPIO_RTC_DAY_R);
224	tm->tm_wday = (v & 0x0f) - 1;
225	tm->tm_yday = day_of_year[tm->tm_mon];
226	tm->tm_yday += (tm->tm_mday - 1);
227	if (tm->tm_mon >= 2) {
228		if (!(tm->tm_year % 4) && (tm->tm_year % 100))
229			tm->tm_yday++;
230	}
231
232	tm->tm_isdst = 0;
233
234	spin_unlock_irq(&moxart_rtc->rtc_lock);
235
236	return 0;
237}
238
239static const struct rtc_class_ops moxart_rtc_ops = {
240	.read_time	= moxart_rtc_read_time,
241	.set_time	= moxart_rtc_set_time,
242};
243
244static int moxart_rtc_probe(struct platform_device *pdev)
245{
246	struct moxart_rtc *moxart_rtc;
247	int ret = 0;
248
249	moxart_rtc = devm_kzalloc(&pdev->dev, sizeof(*moxart_rtc), GFP_KERNEL);
250	if (!moxart_rtc)
251		return -ENOMEM;
252
253	moxart_rtc->gpio_data = devm_gpiod_get(&pdev->dev, "rtc-data",
254					       GPIOD_IN);
255	ret = PTR_ERR_OR_ZERO(moxart_rtc->gpio_data);
256	if (ret) {
257		dev_err(&pdev->dev, "can't get rtc data gpio: %d\n", ret);
258		return ret;
259	}
260
261	moxart_rtc->gpio_sclk = devm_gpiod_get(&pdev->dev, "rtc-sclk",
262					       GPIOD_ASIS);
263	ret = PTR_ERR_OR_ZERO(moxart_rtc->gpio_sclk);
264	if (ret) {
265		dev_err(&pdev->dev, "can't get rtc sclk gpio: %d\n", ret);
266		return ret;
267	}
268
269	moxart_rtc->gpio_reset = devm_gpiod_get(&pdev->dev, "rtc-reset",
270						GPIOD_ASIS);
271	ret = PTR_ERR_OR_ZERO(moxart_rtc->gpio_reset);
272	if (ret) {
273		dev_err(&pdev->dev, "can't get rtc reset gpio: %d\n", ret);
274		return ret;
275	}
276
277	spin_lock_init(&moxart_rtc->rtc_lock);
278	platform_set_drvdata(pdev, moxart_rtc);
279
280	moxart_rtc->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
281						   &moxart_rtc_ops,
282						   THIS_MODULE);
283	if (IS_ERR(moxart_rtc->rtc)) {
284		dev_err(&pdev->dev, "devm_rtc_device_register failed\n");
285		return PTR_ERR(moxart_rtc->rtc);
286	}
287
288	return 0;
289}
290
291static const struct of_device_id moxart_rtc_match[] = {
292	{ .compatible = "moxa,moxart-rtc" },
293	{ },
294};
295MODULE_DEVICE_TABLE(of, moxart_rtc_match);
296
297static struct platform_driver moxart_rtc_driver = {
298	.probe	= moxart_rtc_probe,
299	.driver	= {
300		.name		= "moxart-rtc",
301		.of_match_table	= moxart_rtc_match,
302	},
303};
304module_platform_driver(moxart_rtc_driver);
305
306MODULE_DESCRIPTION("MOXART RTC driver");
307MODULE_LICENSE("GPL");
308MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");
309