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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 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
89static 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
103static const struct rtc_class_ops r9701_rtc_ops = {
104 .read_time = r9701_get_datetime,
105 .set_time = r9701_set_datetime,
106};
107
108static 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
133static struct spi_driver r9701_driver = {
134 .driver = {
135 .name = "rtc-r9701",
136 },
137 .probe = r9701_probe,
138};
139
140module_spi_driver(r9701_driver);
141
142MODULE_DESCRIPTION("r9701 spi RTC driver");
143MODULE_AUTHOR("Magnus Damm <[email protected]>");
144MODULE_LICENSE("GPL");
145MODULE_ALIAS("spi:rtc-r9701");