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
|
/*
* SPI Driver for Microchip MCP795 RTC
*
* Copyright (C) Josef Gajdusek <atx@atx.name>
*
* based on other Linux RTC drivers
*
* Device datasheet:
* http://ww1.microchip.com/downloads/en/DeviceDoc/22280A.pdf
*
* 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/module.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/printk.h>
#include <linux/spi/spi.h>
#include <linux/rtc.h>
#include <linux/of.h>
/* MCP795 Instructions, see datasheet table 3-1 */
#define MCP795_EEREAD 0x03
#define MCP795_EEWRITE 0x02
#define MCP795_EEWRDI 0x04
#define MCP795_EEWREN 0x06
#define MCP795_SRREAD 0x05
#define MCP795_SRWRITE 0x01
#define MCP795_READ 0x13
#define MCP795_WRITE 0x12
#define MCP795_UNLOCK 0x14
#define MCP795_IDWRITE 0x32
#define MCP795_IDREAD 0x33
#define MCP795_CLRWDT 0x44
#define MCP795_CLRRAM 0x54
#define MCP795_ST_BIT 0x80
#define MCP795_24_BIT 0x40
static int mcp795_rtcc_read(struct device *dev, u8 addr, u8 *buf, u8 count)
{
struct spi_device *spi = to_spi_device(dev);
int ret;
u8 tx[2];
tx[0] = MCP795_READ;
tx[1] = addr;
ret = spi_write_then_read(spi, tx, sizeof(tx), buf, count);
if (ret)
dev_err(dev, "Failed reading %d bytes from address %x.\n",
count, addr);
return ret;
}
static int mcp795_rtcc_write(struct device *dev, u8 addr, u8 *data, u8 count)
{
struct spi_device *spi = to_spi_device(dev);
int ret;
u8 tx[2 + count];
tx[0] = MCP795_WRITE;
tx[1] = addr;
memcpy(&tx[2], data, count);
ret = spi_write(spi, tx, 2 + count);
if (ret)
dev_err(dev, "Failed to write %d bytes to address %x.\n",
count, addr);
return ret;
}
static int mcp795_rtcc_set_bits(struct device *dev, u8 addr, u8 mask, u8 state)
{
int ret;
u8 tmp;
ret = mcp795_rtcc_read(dev, addr, &tmp, 1);
if (ret)
return ret;
if ((tmp & mask) != state) {
tmp = (tmp & ~mask) | state;
ret = mcp795_rtcc_write(dev, addr, &tmp, 1);
}
return ret;
}
static int mcp795_set_time(struct device *dev, struct rtc_time *tim)
{
int ret;
u8 data[7];
/* Read first, so we can leave config bits untouched */
ret = mcp795_rtcc_read(dev, 0x01, data, sizeof(data));
if (ret)
return ret;
data[0] = (data[0] & 0x80) | ((tim->tm_sec / 10) << 4) | (tim->tm_sec % 10);
data[1] = (data[1] & 0x80) | ((tim->tm_min / 10) << 4) | (tim->tm_min % 10);
data[2] = ((tim->tm_hour / 10) << 4) | (tim->tm_hour % 10);
data[4] = ((tim->tm_mday / 10) << 4) | ((tim->tm_mday) % 10);
data[5] = (data[5] & 0x10) | (tim->tm_mon / 10) | (tim->tm_mon % 10);
if (tim->tm_year > 100)
tim->tm_year -= 100;
data[6] = ((tim->tm_year / 10) << 4) | (tim->tm_year % 10);
ret = mcp795_rtcc_write(dev, 0x01, data, sizeof(data));
if (ret)
return ret;
dev_dbg(dev, "Set mcp795: %04d-%02d-%02d %02d:%02d:%02d\n",
tim->tm_year + 1900, tim->tm_mon, tim->tm_mday,
tim->tm_hour, tim->tm_min, tim->tm_sec);
return 0;
}
static int mcp795_read_time(struct device *dev, struct rtc_time *tim)
{
int ret;
u8 data[7];
ret = mcp795_rtcc_read(dev, 0x01, data, sizeof(data));
if (ret)
return ret;
tim->tm_sec = ((data[0] & 0x70) >> 4) * 10 + (data[0] & 0x0f);
tim->tm_min = ((data[1] & 0x70) >> 4) * 10 + (data[1] & 0x0f);
tim->tm_hour = ((data[2] & 0x30) >> 4) * 10 + (data[2] & 0x0f);
tim->tm_mday = ((data[4] & 0x30) >> 4) * 10 + (data[4] & 0x0f);
tim->tm_mon = ((data[5] & 0x10) >> 4) * 10 + (data[5] & 0x0f);
tim->tm_year = ((data[6] & 0xf0) >> 4) * 10 + (data[6] & 0x0f) + 100; /* Assume we are in 20xx */
dev_dbg(dev, "Read from mcp795: %04d-%02d-%02d %02d:%02d:%02d\n",
tim->tm_year + 1900, tim->tm_mon, tim->tm_mday,
tim->tm_hour, tim->tm_min, tim->tm_sec);
return rtc_valid_tm(tim);
}
static struct rtc_class_ops mcp795_rtc_ops = {
.read_time = mcp795_read_time,
.set_time = mcp795_set_time
};
static int mcp795_probe(struct spi_device *spi)
{
struct rtc_device *rtc;
int ret;
spi->mode = SPI_MODE_0;
spi->bits_per_word = 8;
ret = spi_setup(spi);
if (ret) {
dev_err(&spi->dev, "Unable to setup SPI\n");
return ret;
}
/* Start the oscillator */
mcp795_rtcc_set_bits(&spi->dev, 0x01, MCP795_ST_BIT, MCP795_ST_BIT);
/* Clear the 12 hour mode flag*/
mcp795_rtcc_set_bits(&spi->dev, 0x03, MCP795_24_BIT, 0);
rtc = devm_rtc_device_register(&spi->dev, "rtc-mcp795",
&mcp795_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
spi_set_drvdata(spi, rtc);
return 0;
}
#ifdef CONFIG_OF
static const struct of_device_id mcp795_of_match[] = {
{ .compatible = "maxim,mcp795" },
{ }
};
MODULE_DEVICE_TABLE(of, mcp795_of_match);
#endif
static struct spi_driver mcp795_driver = {
.driver = {
.name = "rtc-mcp795",
.of_match_table = of_match_ptr(mcp795_of_match),
},
.probe = mcp795_probe,
};
module_spi_driver(mcp795_driver);
MODULE_DESCRIPTION("MCP795 RTC SPI Driver");
MODULE_AUTHOR("Josef Gajdusek <atx@atx.name>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:mcp795");
|
