1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Driver for ST M41T94 SPI RTC |
4 | * |
5 | * Copyright (C) 2008 Kim B. Heino |
6 | */ |
7 | |
8 | #include <linux/module.h> |
9 | #include <linux/kernel.h> |
10 | #include <linux/platform_device.h> |
11 | #include <linux/rtc.h> |
12 | #include <linux/spi/spi.h> |
13 | #include <linux/bcd.h> |
14 | |
15 | #define M41T94_REG_SECONDS 0x01 |
16 | #define M41T94_REG_MINUTES 0x02 |
17 | #define M41T94_REG_HOURS 0x03 |
18 | #define M41T94_REG_WDAY 0x04 |
19 | #define M41T94_REG_DAY 0x05 |
20 | #define M41T94_REG_MONTH 0x06 |
21 | #define M41T94_REG_YEAR 0x07 |
22 | #define M41T94_REG_HT 0x0c |
23 | |
24 | #define M41T94_BIT_HALT 0x40 |
25 | #define M41T94_BIT_STOP 0x80 |
26 | #define M41T94_BIT_CB 0x40 |
27 | #define M41T94_BIT_CEB 0x80 |
28 | |
29 | static int m41t94_set_time(struct device *dev, struct rtc_time *tm) |
30 | { |
31 | struct spi_device *spi = to_spi_device(dev); |
32 | u8 buf[8]; /* write cmd + 7 registers */ |
33 | |
34 | dev_dbg(dev, "%s secs=%d, mins=%d, " |
35 | "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n" , |
36 | "write" , tm->tm_sec, tm->tm_min, |
37 | tm->tm_hour, tm->tm_mday, |
38 | tm->tm_mon, tm->tm_year, tm->tm_wday); |
39 | |
40 | buf[0] = 0x80 | M41T94_REG_SECONDS; /* write time + date */ |
41 | buf[M41T94_REG_SECONDS] = bin2bcd(tm->tm_sec); |
42 | buf[M41T94_REG_MINUTES] = bin2bcd(tm->tm_min); |
43 | buf[M41T94_REG_HOURS] = bin2bcd(tm->tm_hour); |
44 | buf[M41T94_REG_WDAY] = bin2bcd(tm->tm_wday + 1); |
45 | buf[M41T94_REG_DAY] = bin2bcd(tm->tm_mday); |
46 | buf[M41T94_REG_MONTH] = bin2bcd(tm->tm_mon + 1); |
47 | |
48 | buf[M41T94_REG_HOURS] |= M41T94_BIT_CEB; |
49 | if (tm->tm_year >= 100) |
50 | buf[M41T94_REG_HOURS] |= M41T94_BIT_CB; |
51 | buf[M41T94_REG_YEAR] = bin2bcd(tm->tm_year % 100); |
52 | |
53 | return spi_write(spi, buf, len: 8); |
54 | } |
55 | |
56 | static int m41t94_read_time(struct device *dev, struct rtc_time *tm) |
57 | { |
58 | struct spi_device *spi = to_spi_device(dev); |
59 | u8 buf[2]; |
60 | int ret, hour; |
61 | |
62 | /* clear halt update bit */ |
63 | ret = spi_w8r8(spi, M41T94_REG_HT); |
64 | if (ret < 0) |
65 | return ret; |
66 | if (ret & M41T94_BIT_HALT) { |
67 | buf[0] = 0x80 | M41T94_REG_HT; |
68 | buf[1] = ret & ~M41T94_BIT_HALT; |
69 | spi_write(spi, buf, len: 2); |
70 | } |
71 | |
72 | /* clear stop bit */ |
73 | ret = spi_w8r8(spi, M41T94_REG_SECONDS); |
74 | if (ret < 0) |
75 | return ret; |
76 | if (ret & M41T94_BIT_STOP) { |
77 | buf[0] = 0x80 | M41T94_REG_SECONDS; |
78 | buf[1] = ret & ~M41T94_BIT_STOP; |
79 | spi_write(spi, buf, len: 2); |
80 | } |
81 | |
82 | tm->tm_sec = bcd2bin(spi_w8r8(spi, M41T94_REG_SECONDS)); |
83 | tm->tm_min = bcd2bin(spi_w8r8(spi, M41T94_REG_MINUTES)); |
84 | hour = spi_w8r8(spi, M41T94_REG_HOURS); |
85 | tm->tm_hour = bcd2bin(hour & 0x3f); |
86 | tm->tm_wday = bcd2bin(spi_w8r8(spi, M41T94_REG_WDAY)) - 1; |
87 | tm->tm_mday = bcd2bin(spi_w8r8(spi, M41T94_REG_DAY)); |
88 | tm->tm_mon = bcd2bin(spi_w8r8(spi, M41T94_REG_MONTH)) - 1; |
89 | tm->tm_year = bcd2bin(spi_w8r8(spi, M41T94_REG_YEAR)); |
90 | if ((hour & M41T94_BIT_CB) || !(hour & M41T94_BIT_CEB)) |
91 | tm->tm_year += 100; |
92 | |
93 | dev_dbg(dev, "%s secs=%d, mins=%d, " |
94 | "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n" , |
95 | "read" , tm->tm_sec, tm->tm_min, |
96 | tm->tm_hour, tm->tm_mday, |
97 | tm->tm_mon, tm->tm_year, tm->tm_wday); |
98 | |
99 | return 0; |
100 | } |
101 | |
102 | static const struct rtc_class_ops m41t94_rtc_ops = { |
103 | .read_time = m41t94_read_time, |
104 | .set_time = m41t94_set_time, |
105 | }; |
106 | |
107 | static struct spi_driver m41t94_driver; |
108 | |
109 | static int m41t94_probe(struct spi_device *spi) |
110 | { |
111 | struct rtc_device *rtc; |
112 | int res; |
113 | |
114 | spi->bits_per_word = 8; |
115 | spi_setup(spi); |
116 | |
117 | res = spi_w8r8(spi, M41T94_REG_SECONDS); |
118 | if (res < 0) { |
119 | dev_err(&spi->dev, "not found.\n" ); |
120 | return res; |
121 | } |
122 | |
123 | rtc = devm_rtc_device_register(dev: &spi->dev, name: m41t94_driver.driver.name, |
124 | ops: &m41t94_rtc_ops, THIS_MODULE); |
125 | if (IS_ERR(ptr: rtc)) |
126 | return PTR_ERR(ptr: rtc); |
127 | |
128 | spi_set_drvdata(spi, data: rtc); |
129 | |
130 | return 0; |
131 | } |
132 | |
133 | static struct spi_driver m41t94_driver = { |
134 | .driver = { |
135 | .name = "rtc-m41t94" , |
136 | }, |
137 | .probe = m41t94_probe, |
138 | }; |
139 | |
140 | module_spi_driver(m41t94_driver); |
141 | |
142 | MODULE_AUTHOR("Kim B. Heino <Kim.Heino@bluegiga.com>" ); |
143 | MODULE_DESCRIPTION("Driver for ST M41T94 SPI RTC" ); |
144 | MODULE_LICENSE("GPL" ); |
145 | MODULE_ALIAS("spi:rtc-m41t94" ); |
146 | |