tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Driver for Epson RTC-9701JE
4 *
5 * Copyright (C) 2008 Magnus Damm
6 *
7 * Based on rtc-max6902.c
8 *
9 * Copyright (C) 2006 8D Technologies inc.
10 * Copyright (C) 2004 Compulab Ltd.
11 */
12
13#include <linux/module.h>
14#include <linux/kernel.h>
15#include <linux/platform_device.h>
16#include <linux/device.h>
17#include <linux/init.h>
18#include <linux/rtc.h>
19#include <linux/spi/spi.h>
20#include <linux/bcd.h>
21#include <linux/delay.h>
22#include <linux/bitops.h>
23
24#define RSECCNT 0x00 /* Second Counter */
25#define RMINCNT 0x01 /* Minute Counter */
26#define RHRCNT 0x02 /* Hour Counter */
27#define RWKCNT 0x03 /* Week Counter */
28#define RDAYCNT 0x04 /* Day Counter */
29#define RMONCNT 0x05 /* Month Counter */
30#define RYRCNT 0x06 /* Year Counter */
31#define R100CNT 0x07 /* Y100 Counter */
32#define RMINAR 0x08 /* Minute Alarm */
33#define RHRAR 0x09 /* Hour Alarm */
34#define RWKAR 0x0a /* Week/Day Alarm */
35#define RTIMCNT 0x0c /* Interval Timer */
36#define REXT 0x0d /* Extension Register */
37#define RFLAG 0x0e /* RTC Flag Register */
38#define RCR 0x0f /* RTC Control Register */
39
40static int write_reg(struct device *dev, int address, unsigned char data)
41{
42 struct spi_device *spi = to_spi_device(dev);
43 unsigned char buf[2];
44
45 buf[0] = address & 0x7f;
46 buf[1] = data;
47
48 return spi_write(spi, buf, ARRAY_SIZE(buf));
49}
50
51static int read_regs(struct device *dev, unsigned char *regs, int no_regs)
52{
53 struct spi_device *spi = to_spi_device(dev);
54 u8 txbuf[1], rxbuf[1];
55 int k, ret;
56
57 ret = 0;
58
59 for (k = 0; ret == 0 && k < no_regs; k++) {
60 txbuf[0] = 0x80 | regs[k];
61 ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
62 regs[k] = rxbuf[0];
63 }
64
65 return ret;
66}
67
68static int r9701_get_datetime(struct device *dev, struct rtc_time *dt)
69{
70 int ret;
71 unsigned char buf[] = { RSECCNT, RMINCNT, RHRCNT,
72 RDAYCNT, RMONCNT, RYRCNT };
73
74 ret = read_regs(dev, buf, ARRAY_SIZE(buf));
75 if (ret)
76 return ret;
77
78 memset(dt, 0, sizeof(*dt));
79
80 dt->tm_sec = bcd2bin(buf[0]); /* RSECCNT */
81 dt->tm_min = bcd2bin(buf[1]); /* RMINCNT */
82 dt->tm_hour = bcd2bin(buf[2]); /* RHRCNT */
83
84 dt->tm_mday = bcd2bin(buf[3]); /* RDAYCNT */
85 dt->tm_mon = bcd2bin(buf[4]) - 1; /* RMONCNT */
86 dt->tm_year = bcd2bin(buf[5]) + 100; /* RYRCNT */
87
88 /* the rtc device may contain illegal values on power up
89 * according to the data sheet. make sure they are valid.
90 */
91
92 return 0;
93}
94
95static int r9701_set_datetime(struct device *dev, struct rtc_time *dt)
96{
97 int ret, year;
98
99 year = dt->tm_year + 1900;
100 if (year >= 2100 || year < 2000)
101 return -EINVAL;
102
103 ret = write_reg(dev, RHRCNT, bin2bcd(dt->tm_hour));
104 ret = ret ? ret : write_reg(dev, RMINCNT, bin2bcd(dt->tm_min));
105 ret = ret ? ret : write_reg(dev, RSECCNT, bin2bcd(dt->tm_sec));
106 ret = ret ? ret : write_reg(dev, RDAYCNT, bin2bcd(dt->tm_mday));
107 ret = ret ? ret : write_reg(dev, RMONCNT, bin2bcd(dt->tm_mon + 1));
108 ret = ret ? ret : write_reg(dev, RYRCNT, bin2bcd(dt->tm_year - 100));
109 ret = ret ? ret : write_reg(dev, RWKCNT, 1 << dt->tm_wday);
110
111 return ret;
112}
113
114static const struct rtc_class_ops r9701_rtc_ops = {
115 .read_time = r9701_get_datetime,
116 .set_time = r9701_set_datetime,
117};
118
119static int r9701_probe(struct spi_device *spi)
120{
121 struct rtc_device *rtc;
122 struct rtc_time dt;
123 unsigned char tmp;
124 int res;
125
126 tmp = R100CNT;
127 res = read_regs(&spi->dev, &tmp, 1);
128 if (res || tmp != 0x20) {
129 dev_err(&spi->dev, "cannot read RTC register\n");
130 return -ENODEV;
131 }
132
133 /*
134 * The device seems to be present. Now check if the registers
135 * contain invalid values. If so, try to write a default date:
136 * 2000/1/1 00:00:00
137 */
138 if (r9701_get_datetime(&spi->dev, &dt)) {
139 dev_info(&spi->dev, "trying to repair invalid date/time\n");
140 dt.tm_sec = 0;
141 dt.tm_min = 0;
142 dt.tm_hour = 0;
143 dt.tm_mday = 1;
144 dt.tm_mon = 0;
145 dt.tm_year = 100;
146
147 if (r9701_set_datetime(&spi->dev, &dt) ||
148 r9701_get_datetime(&spi->dev, &dt)) {
149 dev_err(&spi->dev, "cannot repair RTC register\n");
150 return -ENODEV;
151 }
152 }
153
154 rtc = devm_rtc_device_register(&spi->dev, "r9701",
155 &r9701_rtc_ops, THIS_MODULE);
156 if (IS_ERR(rtc))
157 return PTR_ERR(rtc);
158
159 spi_set_drvdata(spi, rtc);
160
161 return 0;
162}
163
164static struct spi_driver r9701_driver = {
165 .driver = {
166 .name = "rtc-r9701",
167 },
168 .probe = r9701_probe,
169};
170
171module_spi_driver(r9701_driver);
172
173MODULE_DESCRIPTION("r9701 spi RTC driver");
174MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
175MODULE_LICENSE("GPL");
176MODULE_ALIAS("spi:rtc-r9701");