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1// SPDX-License-Identifier: GPL-2.0-only
2/* drivers/rtc/rtc-rx4581.c
3 *
4 * written by Torben Hohn <[email protected]>
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 <[email protected]>
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
66static 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
79static 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 */
94static 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
170static 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
249static const struct rtc_class_ops rx4581_rtc_ops = {
250 .read_time = rx4581_get_datetime,
251 .set_time = rx4581_set_datetime,
252};
253
254static 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
273static const struct spi_device_id rx4581_id[] = {
274 { "rx4581", 0 },
275 { }
276};
277MODULE_DEVICE_TABLE(spi, rx4581_id);
278
279static struct spi_driver rx4581_driver = {
280 .driver = {
281 .name = "rtc-rx4581",
282 },
283 .probe = rx4581_probe,
284 .id_table = rx4581_id,
285};
286
287module_spi_driver(rx4581_driver);
288
289MODULE_DESCRIPTION("rx4581 spi RTC driver");
290MODULE_AUTHOR("Torben Hohn");
291MODULE_LICENSE("GPL");
292MODULE_ALIAS("spi:rtc-rx4581");