1 // SPDX-License-Identifier: GPL-2.0-only
2 /* drivers/rtc/rtc-rx4581.c
3  *
4  * written by Torben Hohn <torbenh@linutronix.de>
5  *
6  * Based on:
7  * drivers/rtc/rtc-max6902.c
8  *
9  * Copyright (C) 2006 8D Technologies inc.
10  * Copyright (C) 2004 Compulab Ltd.
11  *
12  * Driver for MAX6902 spi RTC
13  *
14  * and based on:
15  * drivers/rtc/rtc-rx8581.c
16  *
17  * An I2C driver for the Epson RX8581 RTC
18  *
19  * Author: Martyn Welch <martyn.welch@ge.com>
20  * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
21  *
22  * Based on: rtc-pcf8563.c (An I2C driver for the Philips PCF8563 RTC)
23  * Copyright 2005-06 Tower Technologies
24  */
25 
26 #include <linux/module.h>
27 #include <linux/kernel.h>
28 #include <linux/platform_device.h>
29 #include <linux/init.h>
30 #include <linux/rtc.h>
31 #include <linux/spi/spi.h>
32 #include <linux/bcd.h>
33 
34 #define RX4581_REG_SC		0x00 /* Second in BCD */
35 #define RX4581_REG_MN		0x01 /* Minute in BCD */
36 #define RX4581_REG_HR		0x02 /* Hour in BCD */
37 #define RX4581_REG_DW		0x03 /* Day of Week */
38 #define RX4581_REG_DM		0x04 /* Day of Month in BCD */
39 #define RX4581_REG_MO		0x05 /* Month in BCD */
40 #define RX4581_REG_YR		0x06 /* Year in BCD */
41 #define RX4581_REG_RAM		0x07 /* RAM */
42 #define RX4581_REG_AMN		0x08 /* Alarm Min in BCD*/
43 #define RX4581_REG_AHR		0x09 /* Alarm Hour in BCD */
44 #define RX4581_REG_ADM		0x0A
45 #define RX4581_REG_ADW		0x0A
46 #define RX4581_REG_TMR0		0x0B
47 #define RX4581_REG_TMR1		0x0C
48 #define RX4581_REG_EXT		0x0D /* Extension Register */
49 #define RX4581_REG_FLAG		0x0E /* Flag Register */
50 #define RX4581_REG_CTRL		0x0F /* Control Register */
51 
52 
53 /* Flag Register bit definitions */
54 #define RX4581_FLAG_UF		0x20 /* Update */
55 #define RX4581_FLAG_TF		0x10 /* Timer */
56 #define RX4581_FLAG_AF		0x08 /* Alarm */
57 #define RX4581_FLAG_VLF		0x02 /* Voltage Low */
58 
59 /* Control Register bit definitions */
60 #define RX4581_CTRL_UIE		0x20 /* Update Interrupt Enable */
61 #define RX4581_CTRL_TIE		0x10 /* Timer Interrupt Enable */
62 #define RX4581_CTRL_AIE		0x08 /* Alarm Interrupt Enable */
63 #define RX4581_CTRL_STOP	0x02 /* STOP bit */
64 #define RX4581_CTRL_RESET	0x01 /* RESET bit */
65 
rx4581_set_reg(struct device * dev,unsigned char address,unsigned char data)66 static int rx4581_set_reg(struct device *dev, unsigned char address,
67 				unsigned char data)
68 {
69 	struct spi_device *spi = to_spi_device(dev);
70 	unsigned char buf[2];
71 
72 	/* high nibble must be '0' to write */
73 	buf[0] = address & 0x0f;
74 	buf[1] = data;
75 
76 	return spi_write_then_read(spi, buf, 2, NULL, 0);
77 }
78 
rx4581_get_reg(struct device * dev,unsigned char address,unsigned char * data)79 static int rx4581_get_reg(struct device *dev, unsigned char address,
80 				unsigned char *data)
81 {
82 	struct spi_device *spi = to_spi_device(dev);
83 
84 	/* Set MSB to indicate read */
85 	*data = address | 0x80;
86 
87 	return spi_write_then_read(spi, data, 1, data, 1);
88 }
89 
90 /*
91  * In the routines that deal directly with the rx8581 hardware, we use
92  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
93  */
rx4581_get_datetime(struct device * dev,struct rtc_time * tm)94 static int rx4581_get_datetime(struct device *dev, struct rtc_time *tm)
95 {
96 	struct spi_device *spi = to_spi_device(dev);
97 	unsigned char date[7];
98 	unsigned char data;
99 	int err;
100 
101 	/* First we ensure that the "update flag" is not set, we read the
102 	 * time and date then re-read the "update flag". If the update flag
103 	 * has been set, we know that the time has changed during the read so
104 	 * we repeat the whole process again.
105 	 */
106 	err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
107 	if (err != 0) {
108 		dev_err(dev, "Unable to read device flags\n");
109 		return -EIO;
110 	}
111 
112 	do {
113 		/* If update flag set, clear it */
114 		if (data & RX4581_FLAG_UF) {
115 			err = rx4581_set_reg(dev,
116 				RX4581_REG_FLAG, (data & ~RX4581_FLAG_UF));
117 			if (err != 0) {
118 				dev_err(dev, "Unable to write device "
119 					"flags\n");
120 				return -EIO;
121 			}
122 		}
123 
124 		/* Now read time and date */
125 		date[0] = 0x80;
126 		err = spi_write_then_read(spi, date, 1, date, 7);
127 		if (err < 0) {
128 			dev_err(dev, "Unable to read date\n");
129 			return -EIO;
130 		}
131 
132 		/* Check flag register */
133 		err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
134 		if (err != 0) {
135 			dev_err(dev, "Unable to read device flags\n");
136 			return -EIO;
137 		}
138 	} while (data & RX4581_FLAG_UF);
139 
140 	if (data & RX4581_FLAG_VLF)
141 		dev_info(dev,
142 			"low voltage detected, date/time is not reliable.\n");
143 
144 	dev_dbg(dev,
145 		"%s: raw data is sec=%02x, min=%02x, hr=%02x, "
146 		"wday=%02x, mday=%02x, mon=%02x, year=%02x\n",
147 		__func__,
148 		date[0], date[1], date[2], date[3], date[4], date[5], date[6]);
149 
150 	tm->tm_sec = bcd2bin(date[RX4581_REG_SC] & 0x7F);
151 	tm->tm_min = bcd2bin(date[RX4581_REG_MN] & 0x7F);
152 	tm->tm_hour = bcd2bin(date[RX4581_REG_HR] & 0x3F); /* rtc hr 0-23 */
153 	tm->tm_wday = ilog2(date[RX4581_REG_DW] & 0x7F);
154 	tm->tm_mday = bcd2bin(date[RX4581_REG_DM] & 0x3F);
155 	tm->tm_mon = bcd2bin(date[RX4581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
156 	tm->tm_year = bcd2bin(date[RX4581_REG_YR]);
157 	if (tm->tm_year < 70)
158 		tm->tm_year += 100;	/* assume we are in 1970...2069 */
159 
160 
161 	dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
162 		"mday=%d, mon=%d, year=%d, wday=%d\n",
163 		__func__,
164 		tm->tm_sec, tm->tm_min, tm->tm_hour,
165 		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
166 
167 	return 0;
168 }
169 
rx4581_set_datetime(struct device * dev,struct rtc_time * tm)170 static int rx4581_set_datetime(struct device *dev, struct rtc_time *tm)
171 {
172 	struct spi_device *spi = to_spi_device(dev);
173 	int err;
174 	unsigned char buf[8], data;
175 
176 	dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, "
177 		"mday=%d, mon=%d, year=%d, wday=%d\n",
178 		__func__,
179 		tm->tm_sec, tm->tm_min, tm->tm_hour,
180 		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
181 
182 	buf[0] = 0x00;
183 	/* hours, minutes and seconds */
184 	buf[RX4581_REG_SC+1] = bin2bcd(tm->tm_sec);
185 	buf[RX4581_REG_MN+1] = bin2bcd(tm->tm_min);
186 	buf[RX4581_REG_HR+1] = bin2bcd(tm->tm_hour);
187 
188 	buf[RX4581_REG_DM+1] = bin2bcd(tm->tm_mday);
189 
190 	/* month, 1 - 12 */
191 	buf[RX4581_REG_MO+1] = bin2bcd(tm->tm_mon + 1);
192 
193 	/* year and century */
194 	buf[RX4581_REG_YR+1] = bin2bcd(tm->tm_year % 100);
195 	buf[RX4581_REG_DW+1] = (0x1 << tm->tm_wday);
196 
197 	/* Stop the clock */
198 	err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data);
199 	if (err != 0) {
200 		dev_err(dev, "Unable to read control register\n");
201 		return -EIO;
202 	}
203 
204 	err = rx4581_set_reg(dev, RX4581_REG_CTRL,
205 		(data | RX4581_CTRL_STOP));
206 	if (err != 0) {
207 		dev_err(dev, "Unable to write control register\n");
208 		return -EIO;
209 	}
210 
211 	/* write register's data */
212 	err = spi_write_then_read(spi, buf, 8, NULL, 0);
213 	if (err != 0) {
214 		dev_err(dev, "Unable to write to date registers\n");
215 		return -EIO;
216 	}
217 
218 	/* get VLF and clear it */
219 	err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
220 	if (err != 0) {
221 		dev_err(dev, "Unable to read flag register\n");
222 		return -EIO;
223 	}
224 
225 	err = rx4581_set_reg(dev, RX4581_REG_FLAG,
226 		(data & ~(RX4581_FLAG_VLF)));
227 	if (err != 0) {
228 		dev_err(dev, "Unable to write flag register\n");
229 		return -EIO;
230 	}
231 
232 	/* Restart the clock */
233 	err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data);
234 	if (err != 0) {
235 		dev_err(dev, "Unable to read control register\n");
236 		return -EIO;
237 	}
238 
239 	err = rx4581_set_reg(dev, RX4581_REG_CTRL,
240 		(data & ~(RX4581_CTRL_STOP)));
241 	if (err != 0) {
242 		dev_err(dev, "Unable to write control register\n");
243 		return -EIO;
244 	}
245 
246 	return 0;
247 }
248 
249 static const struct rtc_class_ops rx4581_rtc_ops = {
250 	.read_time	= rx4581_get_datetime,
251 	.set_time	= rx4581_set_datetime,
252 };
253 
rx4581_probe(struct spi_device * spi)254 static int rx4581_probe(struct spi_device *spi)
255 {
256 	struct rtc_device *rtc;
257 	unsigned char tmp;
258 	int res;
259 
260 	res = rx4581_get_reg(&spi->dev, RX4581_REG_SC, &tmp);
261 	if (res != 0)
262 		return res;
263 
264 	rtc = devm_rtc_device_register(&spi->dev, "rx4581",
265 				&rx4581_rtc_ops, THIS_MODULE);
266 	if (IS_ERR(rtc))
267 		return PTR_ERR(rtc);
268 
269 	spi_set_drvdata(spi, rtc);
270 	return 0;
271 }
272 
273 static const struct spi_device_id rx4581_id[] = {
274 	{ "rx4581", 0 },
275 	{ }
276 };
277 MODULE_DEVICE_TABLE(spi, rx4581_id);
278 
279 static struct spi_driver rx4581_driver = {
280 	.driver = {
281 		.name	= "rtc-rx4581",
282 	},
283 	.probe	= rx4581_probe,
284 	.id_table = rx4581_id,
285 };
286 
287 module_spi_driver(rx4581_driver);
288 
289 MODULE_DESCRIPTION("rx4581 spi RTC driver");
290 MODULE_AUTHOR("Torben Hohn");
291 MODULE_LICENSE("GPL");
292 MODULE_ALIAS("spi:rtc-rx4581");
293