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
|
// SPDX-License-Identifier: GPL-2.0-only
/*
* Dallas DS1302 RTC Support
*
* Copyright (C) 2002 David McCullough
* Copyright (C) 2003 - 2007 Paul Mundt
*/
#include <linux/bcd.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/rtc.h>
#include <linux/spi/spi.h>
#define RTC_CMD_READ 0x81 /* Read command */
#define RTC_CMD_WRITE 0x80 /* Write command */
#define RTC_CMD_WRITE_ENABLE 0x00 /* Write enable */
#define RTC_CMD_WRITE_DISABLE 0x80 /* Write disable */
#define RTC_ADDR_RAM0 0x20 /* Address of RAM0 */
#define RTC_ADDR_TCR 0x08 /* Address of trickle charge register */
#define RTC_CLCK_BURST 0x1F /* Address of clock burst */
#define RTC_CLCK_LEN 0x08 /* Size of clock burst */
#define RTC_ADDR_CTRL 0x07 /* Address of control register */
#define RTC_ADDR_YEAR 0x06 /* Address of year register */
#define RTC_ADDR_DAY 0x05 /* Address of day of week register */
#define RTC_ADDR_MON 0x04 /* Address of month register */
#define RTC_ADDR_DATE 0x03 /* Address of day of month register */
#define RTC_ADDR_HOUR 0x02 /* Address of hour register */
#define RTC_ADDR_MIN 0x01 /* Address of minute register */
#define RTC_ADDR_SEC 0x00 /* Address of second register */
static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *time)
{
struct spi_device *spi = dev_get_drvdata(dev);
u8 buf[1 + RTC_CLCK_LEN];
u8 *bp;
int status;
/* Enable writing */
bp = buf;
*bp++ = RTC_ADDR_CTRL << 1 | RTC_CMD_WRITE;
*bp++ = RTC_CMD_WRITE_ENABLE;
status = spi_write_then_read(spi, buf, 2,
NULL, 0);
if (status)
return status;
/* Write registers starting at the first time/date address. */
bp = buf;
*bp++ = RTC_CLCK_BURST << 1 | RTC_CMD_WRITE;
*bp++ = bin2bcd(time->tm_sec);
*bp++ = bin2bcd(time->tm_min);
*bp++ = bin2bcd(time->tm_hour);
*bp++ = bin2bcd(time->tm_mday);
*bp++ = bin2bcd(time->tm_mon + 1);
*bp++ = time->tm_wday + 1;
*bp++ = bin2bcd(time->tm_year % 100);
*bp++ = RTC_CMD_WRITE_DISABLE;
/* use write-then-read since dma from stack is nonportable */
return spi_write_then_read(spi, buf, sizeof(buf),
NULL, 0);
}
static int ds1302_rtc_get_time(struct device *dev, struct rtc_time *time)
{
struct spi_device *spi = dev_get_drvdata(dev);
u8 addr = RTC_CLCK_BURST << 1 | RTC_CMD_READ;
u8 buf[RTC_CLCK_LEN - 1];
int status;
/* Use write-then-read to get all the date/time registers
* since dma from stack is nonportable
*/
status = spi_write_then_read(spi, &addr, sizeof(addr),
buf, sizeof(buf));
if (status < 0)
return status;
/* Decode the registers */
time->tm_sec = bcd2bin(buf[RTC_ADDR_SEC]);
time->tm_min = bcd2bin(buf[RTC_ADDR_MIN]);
time->tm_hour = bcd2bin(buf[RTC_ADDR_HOUR]);
time->tm_wday = buf[RTC_ADDR_DAY] - 1;
time->tm_mday = bcd2bin(buf[RTC_ADDR_DATE]);
time->tm_mon = bcd2bin(buf[RTC_ADDR_MON]) - 1;
time->tm_year = bcd2bin(buf[RTC_ADDR_YEAR]) + 100;
return 0;
}
static const struct rtc_class_ops ds1302_rtc_ops = {
.read_time = ds1302_rtc_get_time,
.set_time = ds1302_rtc_set_time,
};
static int ds1302_probe(struct spi_device *spi)
{
struct rtc_device *rtc;
u8 addr;
u8 buf[4];
u8 *bp;
int status;
/* Sanity check board setup data. This may be hooked up
* in 3wire mode, but we don't care. Note that unless
* there's an inverter in place, this needs SPI_CS_HIGH!
*/
if (spi->bits_per_word && (spi->bits_per_word != 8)) {
dev_err(&spi->dev, "bad word length\n");
return -EINVAL;
} else if (spi->max_speed_hz > 2000000) {
dev_err(&spi->dev, "speed is too high\n");
return -EINVAL;
} else if (spi->mode & SPI_CPHA) {
dev_err(&spi->dev, "bad mode\n");
return -EINVAL;
}
addr = RTC_ADDR_CTRL << 1 | RTC_CMD_READ;
status = spi_write_then_read(spi, &addr, sizeof(addr), buf, 1);
if (status < 0) {
dev_err(&spi->dev, "control register read error %d\n",
status);
return status;
}
if ((buf[0] & ~RTC_CMD_WRITE_DISABLE) != 0) {
status = spi_write_then_read(spi, &addr, sizeof(addr), buf, 1);
if (status < 0) {
dev_err(&spi->dev, "control register read error %d\n",
status);
return status;
}
if ((buf[0] & ~RTC_CMD_WRITE_DISABLE) != 0) {
dev_err(&spi->dev, "junk in control register\n");
return -ENODEV;
}
}
if (buf[0] == 0) {
bp = buf;
*bp++ = RTC_ADDR_CTRL << 1 | RTC_CMD_WRITE;
*bp++ = RTC_CMD_WRITE_DISABLE;
status = spi_write_then_read(spi, buf, 2, NULL, 0);
if (status < 0) {
dev_err(&spi->dev, "control register write error %d\n",
status);
return status;
}
addr = RTC_ADDR_CTRL << 1 | RTC_CMD_READ;
status = spi_write_then_read(spi, &addr, sizeof(addr), buf, 1);
if (status < 0) {
dev_err(&spi->dev,
"error %d reading control register\n",
status);
return status;
}
if (buf[0] != RTC_CMD_WRITE_DISABLE) {
dev_err(&spi->dev, "failed to detect chip\n");
return -ENODEV;
}
}
spi_set_drvdata(spi, spi);
rtc = devm_rtc_device_register(&spi->dev, "ds1302",
&ds1302_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc)) {
status = PTR_ERR(rtc);
dev_err(&spi->dev, "error %d registering rtc\n", status);
return status;
}
return 0;
}
static int ds1302_remove(struct spi_device *spi)
{
spi_set_drvdata(spi, NULL);
return 0;
}
#ifdef CONFIG_OF
static const struct of_device_id ds1302_dt_ids[] = {
{ .compatible = "maxim,ds1302", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, ds1302_dt_ids);
#endif
static struct spi_driver ds1302_driver = {
.driver.name = "rtc-ds1302",
.driver.of_match_table = of_match_ptr(ds1302_dt_ids),
.probe = ds1302_probe,
.remove = ds1302_remove,
};
module_spi_driver(ds1302_driver);
MODULE_DESCRIPTION("Dallas DS1302 RTC driver");
MODULE_AUTHOR("Paul Mundt, David McCullough");
MODULE_LICENSE("GPL v2");
|
