xref: /openbmc/linux/drivers/rtc/rtc-r9701.c (revision fdcfd854)
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 
write_reg(struct device * dev,int address,unsigned char data)40 static 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 
read_regs(struct device * dev,unsigned char * regs,int no_regs)51 static 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 
r9701_get_datetime(struct device * dev,struct rtc_time * dt)68 static 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 	dt->tm_sec = bcd2bin(buf[0]); /* RSECCNT */
79 	dt->tm_min = bcd2bin(buf[1]); /* RMINCNT */
80 	dt->tm_hour = bcd2bin(buf[2]); /* RHRCNT */
81 
82 	dt->tm_mday = bcd2bin(buf[3]); /* RDAYCNT */
83 	dt->tm_mon = bcd2bin(buf[4]) - 1; /* RMONCNT */
84 	dt->tm_year = bcd2bin(buf[5]) + 100; /* RYRCNT */
85 
86 	return 0;
87 }
88 
r9701_set_datetime(struct device * dev,struct rtc_time * dt)89 static int r9701_set_datetime(struct device *dev, struct rtc_time *dt)
90 {
91 	int ret;
92 
93 	ret = write_reg(dev, RHRCNT, bin2bcd(dt->tm_hour));
94 	ret = ret ? ret : write_reg(dev, RMINCNT, bin2bcd(dt->tm_min));
95 	ret = ret ? ret : write_reg(dev, RSECCNT, bin2bcd(dt->tm_sec));
96 	ret = ret ? ret : write_reg(dev, RDAYCNT, bin2bcd(dt->tm_mday));
97 	ret = ret ? ret : write_reg(dev, RMONCNT, bin2bcd(dt->tm_mon + 1));
98 	ret = ret ? ret : write_reg(dev, RYRCNT, bin2bcd(dt->tm_year - 100));
99 
100 	return ret;
101 }
102 
103 static const struct rtc_class_ops r9701_rtc_ops = {
104 	.read_time	= r9701_get_datetime,
105 	.set_time	= r9701_set_datetime,
106 };
107 
r9701_probe(struct spi_device * spi)108 static int r9701_probe(struct spi_device *spi)
109 {
110 	struct rtc_device *rtc;
111 	unsigned char tmp;
112 	int res;
113 
114 	tmp = R100CNT;
115 	res = read_regs(&spi->dev, &tmp, 1);
116 	if (res || tmp != 0x20) {
117 		dev_err(&spi->dev, "cannot read RTC register\n");
118 		return -ENODEV;
119 	}
120 
121 	rtc = devm_rtc_allocate_device(&spi->dev);
122 	if (IS_ERR(rtc))
123 		return PTR_ERR(rtc);
124 
125 	spi_set_drvdata(spi, rtc);
126 	rtc->ops = &r9701_rtc_ops;
127 	rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
128 	rtc->range_max = RTC_TIMESTAMP_END_2099;
129 
130 	return devm_rtc_register_device(rtc);
131 }
132 
133 static struct spi_driver r9701_driver = {
134 	.driver = {
135 		.name	= "rtc-r9701",
136 	},
137 	.probe	= r9701_probe,
138 };
139 
140 module_spi_driver(r9701_driver);
141 
142 MODULE_DESCRIPTION("r9701 spi RTC driver");
143 MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
144 MODULE_LICENSE("GPL");
145 MODULE_ALIAS("spi:rtc-r9701");
146