1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
|
/*
*
* Driver for ST M41T93 SPI RTC
*
* (c) 2010 Nikolaus Voss, Weinmann Medical GmbH
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/bcd.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/spi/spi.h>
#define M41T93_REG_SSEC 0
#define M41T93_REG_ST_SEC 1
#define M41T93_REG_MIN 2
#define M41T93_REG_CENT_HOUR 3
#define M41T93_REG_WDAY 4
#define M41T93_REG_DAY 5
#define M41T93_REG_MON 6
#define M41T93_REG_YEAR 7
#define M41T93_REG_ALM_HOUR_HT 0xc
#define M41T93_REG_FLAGS 0xf
#define M41T93_FLAG_ST (1 << 7)
#define M41T93_FLAG_OF (1 << 2)
#define M41T93_FLAG_BL (1 << 4)
#define M41T93_FLAG_HT (1 << 6)
static inline int m41t93_set_reg(struct spi_device *spi, u8 addr, u8 data)
{
u8 buf[2];
/* MSB must be '1' to write */
buf[0] = addr | 0x80;
buf[1] = data;
return spi_write(spi, buf, sizeof(buf));
}
static int m41t93_set_time(struct device *dev, struct rtc_time *tm)
{
struct spi_device *spi = to_spi_device(dev);
u8 buf[9] = {0x80}; /* write cmd + 8 data bytes */
u8 * const data = &buf[1]; /* ptr to first data byte */
dev_dbg(dev, "%s secs=%d, mins=%d, "
"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
"write", tm->tm_sec, tm->tm_min,
tm->tm_hour, tm->tm_mday,
tm->tm_mon, tm->tm_year, tm->tm_wday);
if (tm->tm_year < 100) {
dev_warn(&spi->dev, "unsupported date (before 2000-01-01).\n");
return -EINVAL;
}
data[M41T93_REG_SSEC] = 0;
data[M41T93_REG_ST_SEC] = bin2bcd(tm->tm_sec);
data[M41T93_REG_MIN] = bin2bcd(tm->tm_min);
data[M41T93_REG_CENT_HOUR] = bin2bcd(tm->tm_hour) |
((tm->tm_year/100-1) << 6);
data[M41T93_REG_DAY] = bin2bcd(tm->tm_mday);
data[M41T93_REG_WDAY] = bin2bcd(tm->tm_wday + 1);
data[M41T93_REG_MON] = bin2bcd(tm->tm_mon + 1);
data[M41T93_REG_YEAR] = bin2bcd(tm->tm_year % 100);
return spi_write(spi, buf, sizeof(buf));
}
static int m41t93_get_time(struct device *dev, struct rtc_time *tm)
{
struct spi_device *spi = to_spi_device(dev);
const u8 start_addr = 0;
u8 buf[8];
int century_after_1900;
int tmp;
int ret = 0;
/* Check status of clock. Two states must be considered:
1. halt bit (HT) is set: the clock is running but update of readout
registers has been disabled due to power failure. This is normal
case after poweron. Time is valid after resetting HT bit.
2. oscillator fail bit (OF) is set. Oscillator has be stopped and
time is invalid:
a) OF can be immeditely reset.
b) OF cannot be immediately reset: oscillator has to be restarted.
*/
tmp = spi_w8r8(spi, M41T93_REG_ALM_HOUR_HT);
if (tmp < 0)
return tmp;
if (tmp & M41T93_FLAG_HT) {
dev_dbg(&spi->dev, "HT bit is set, reenable clock update.\n");
m41t93_set_reg(spi, M41T93_REG_ALM_HOUR_HT,
tmp & ~M41T93_FLAG_HT);
}
tmp = spi_w8r8(spi, M41T93_REG_FLAGS);
if (tmp < 0)
return tmp;
if (tmp & M41T93_FLAG_OF) {
ret = -EINVAL;
dev_warn(&spi->dev, "OF bit is set, resetting.\n");
m41t93_set_reg(spi, M41T93_REG_FLAGS, tmp & ~M41T93_FLAG_OF);
tmp = spi_w8r8(spi, M41T93_REG_FLAGS);
if (tmp < 0)
return tmp;
else if (tmp & M41T93_FLAG_OF) {
u8 reset_osc = buf[M41T93_REG_ST_SEC] | M41T93_FLAG_ST;
dev_warn(&spi->dev,
"OF bit is still set, kickstarting clock.\n");
m41t93_set_reg(spi, M41T93_REG_ST_SEC, reset_osc);
reset_osc &= ~M41T93_FLAG_ST;
m41t93_set_reg(spi, M41T93_REG_ST_SEC, reset_osc);
}
}
if (tmp & M41T93_FLAG_BL)
dev_warn(&spi->dev, "BL bit is set, replace battery.\n");
/* read actual time/date */
tmp = spi_write_then_read(spi, &start_addr, 1, buf, sizeof(buf));
if (tmp < 0)
return tmp;
tm->tm_sec = bcd2bin(buf[M41T93_REG_ST_SEC]);
tm->tm_min = bcd2bin(buf[M41T93_REG_MIN]);
tm->tm_hour = bcd2bin(buf[M41T93_REG_CENT_HOUR] & 0x3f);
tm->tm_mday = bcd2bin(buf[M41T93_REG_DAY]);
tm->tm_mon = bcd2bin(buf[M41T93_REG_MON]) - 1;
tm->tm_wday = bcd2bin(buf[M41T93_REG_WDAY] & 0x0f) - 1;
century_after_1900 = (buf[M41T93_REG_CENT_HOUR] >> 6) + 1;
tm->tm_year = bcd2bin(buf[M41T93_REG_YEAR]) + century_after_1900 * 100;
dev_dbg(dev, "%s secs=%d, mins=%d, "
"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
"read", tm->tm_sec, tm->tm_min,
tm->tm_hour, tm->tm_mday,
tm->tm_mon, tm->tm_year, tm->tm_wday);
return ret < 0 ? ret : rtc_valid_tm(tm);
}
static const struct rtc_class_ops m41t93_rtc_ops = {
.read_time = m41t93_get_time,
.set_time = m41t93_set_time,
};
static struct spi_driver m41t93_driver;
static int __devinit m41t93_probe(struct spi_device *spi)
{
struct rtc_device *rtc;
int res;
spi->bits_per_word = 8;
spi_setup(spi);
res = spi_w8r8(spi, M41T93_REG_WDAY);
if (res < 0 || (res & 0xf8) != 0) {
dev_err(&spi->dev, "not found 0x%x.\n", res);
return -ENODEV;
}
rtc = rtc_device_register(m41t93_driver.driver.name,
&spi->dev, &m41t93_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
dev_set_drvdata(&spi->dev, rtc);
return 0;
}
static int __devexit m41t93_remove(struct spi_device *spi)
{
struct rtc_device *rtc = platform_get_drvdata(spi);
if (rtc)
rtc_device_unregister(rtc);
return 0;
}
static struct spi_driver m41t93_driver = {
.driver = {
.name = "rtc-m41t93",
.bus = &spi_bus_type,
.owner = THIS_MODULE,
},
.probe = m41t93_probe,
.remove = __devexit_p(m41t93_remove),
};
static __init int m41t93_init(void)
{
return spi_register_driver(&m41t93_driver);
}
module_init(m41t93_init);
static __exit void m41t93_exit(void)
{
spi_unregister_driver(&m41t93_driver);
}
module_exit(m41t93_exit);
MODULE_AUTHOR("Nikolaus Voss <n.voss@weinmann.de>");
MODULE_DESCRIPTION("Driver for ST M41T93 SPI RTC");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:rtc-m41t93");
|
