summaryrefslogtreecommitdiffstats
path: root/drivers/i2c/chips/m41t00.c
blob: 27fc9ff2961a6dd9abff1f1ed9db358f4adb29ac (plain)
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
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
/*
 * drivers/i2c/chips/m41t00.c
 *
 * I2C client/driver for the ST M41T00 Real-Time Clock chip.
 *
 * Author: Mark A. Greer <mgreer@mvista.com>
 *
 * 2005 (c) MontaVista Software, Inc. This file is licensed under
 * the terms of the GNU General Public License version 2. This program
 * is licensed "as is" without any warranty of any kind, whether express
 * or implied.
 */
/*
 * This i2c client/driver wedges between the drivers/char/genrtc.c RTC
 * interface and the SMBus interface of the i2c subsystem.
 * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
 * recommened in .../Documentation/i2c/writing-clients section
 * "Sending and receiving", using SMBus level communication is preferred.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/i2c.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/mutex.h>
#include <linux/workqueue.h>

#include <asm/time.h>
#include <asm/rtc.h>

#define	M41T00_DRV_NAME		"m41t00"

static DEFINE_MUTEX(m41t00_mutex);

static struct i2c_driver m41t00_driver;
static struct i2c_client *save_client;

static unsigned short ignore[] = { I2C_CLIENT_END };
static unsigned short normal_addr[] = { 0x68, I2C_CLIENT_END };

static struct i2c_client_address_data addr_data = {
	.normal_i2c		= normal_addr,
	.probe			= ignore,
	.ignore			= ignore,
};

ulong
m41t00_get_rtc_time(void)
{
	s32	sec, min, hour, day, mon, year;
	s32	sec1, min1, hour1, day1, mon1, year1;
	ulong	limit = 10;

	sec = min = hour = day = mon = year = 0;
	sec1 = min1 = hour1 = day1 = mon1 = year1 = 0;

	mutex_lock(&m41t00_mutex);
	do {
		if (((sec = i2c_smbus_read_byte_data(save_client, 0)) >= 0)
			&& ((min = i2c_smbus_read_byte_data(save_client, 1))
				>= 0)
			&& ((hour = i2c_smbus_read_byte_data(save_client, 2))
				>= 0)
			&& ((day = i2c_smbus_read_byte_data(save_client, 4))
				>= 0)
			&& ((mon = i2c_smbus_read_byte_data(save_client, 5))
				>= 0)
			&& ((year = i2c_smbus_read_byte_data(save_client, 6))
				>= 0)
			&& ((sec == sec1) && (min == min1) && (hour == hour1)
				&& (day == day1) && (mon == mon1)
				&& (year == year1)))

				break;

		sec1 = sec;
		min1 = min;
		hour1 = hour;
		day1 = day;
		mon1 = mon;
		year1 = year;
	} while (--limit > 0);
	mutex_unlock(&m41t00_mutex);

	if (limit == 0) {
		dev_warn(&save_client->dev,
			"m41t00: can't read rtc chip\n");
		sec = min = hour = day = mon = year = 0;
	}

	sec &= 0x7f;
	min &= 0x7f;
	hour &= 0x3f;
	day &= 0x3f;
	mon &= 0x1f;
	year &= 0xff;

	BCD_TO_BIN(sec);
	BCD_TO_BIN(min);
	BCD_TO_BIN(hour);
	BCD_TO_BIN(day);
	BCD_TO_BIN(mon);
	BCD_TO_BIN(year);

	year += 1900;
	if (year < 1970)
		year += 100;

	return mktime(year, mon, day, hour, min, sec);
}

static void
m41t00_set(void *arg)
{
	struct rtc_time	tm;
	ulong	nowtime = *(ulong *)arg;

	to_tm(nowtime, &tm);
	tm.tm_year = (tm.tm_year - 1900) % 100;

	BIN_TO_BCD(tm.tm_sec);
	BIN_TO_BCD(tm.tm_min);
	BIN_TO_BCD(tm.tm_hour);
	BIN_TO_BCD(tm.tm_mon);
	BIN_TO_BCD(tm.tm_mday);
	BIN_TO_BCD(tm.tm_year);

	mutex_lock(&m41t00_mutex);
	if ((i2c_smbus_write_byte_data(save_client, 0, tm.tm_sec & 0x7f) < 0)
		|| (i2c_smbus_write_byte_data(save_client, 1, tm.tm_min & 0x7f)
			< 0)
		|| (i2c_smbus_write_byte_data(save_client, 2, tm.tm_hour & 0x7f)
			< 0)
		|| (i2c_smbus_write_byte_data(save_client, 4, tm.tm_mday & 0x7f)
			< 0)
		|| (i2c_smbus_write_byte_data(save_client, 5, tm.tm_mon & 0x7f)
			< 0)
		|| (i2c_smbus_write_byte_data(save_client, 6, tm.tm_year & 0x7f)
			< 0))

		dev_warn(&save_client->dev,"m41t00: can't write to rtc chip\n");

	mutex_unlock(&m41t00_mutex);
	return;
}

static ulong new_time;
static struct workqueue_struct *m41t00_wq;
static DECLARE_WORK(m41t00_work, m41t00_set, &new_time);

int
m41t00_set_rtc_time(ulong nowtime)
{
	new_time = nowtime;

	if (in_interrupt())
		queue_work(m41t00_wq, &m41t00_work);
	else
		m41t00_set(&new_time);

	return 0;
}

/*
 *****************************************************************************
 *
 *	Driver Interface
 *
 *****************************************************************************
 */
static int
m41t00_probe(struct i2c_adapter *adap, int addr, int kind)
{
	struct i2c_client *client;
	int rc;

	client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
	if (!client)
		return -ENOMEM;

	strncpy(client->name, M41T00_DRV_NAME, I2C_NAME_SIZE);
	client->addr = addr;
	client->adapter = adap;
	client->driver = &m41t00_driver;

	if ((rc = i2c_attach_client(client)) != 0) {
		kfree(client);
		return rc;
	}

	m41t00_wq = create_singlethread_workqueue("m41t00");
	save_client = client;
	return 0;
}

static int
m41t00_attach(struct i2c_adapter *adap)
{
	return i2c_probe(adap, &addr_data, m41t00_probe);
}

static int
m41t00_detach(struct i2c_client *client)
{
	int	rc;

	if ((rc = i2c_detach_client(client)) == 0) {
		kfree(client);
		destroy_workqueue(m41t00_wq);
	}
	return rc;
}

static struct i2c_driver m41t00_driver = {
	.driver = {
		.name	= M41T00_DRV_NAME,
	},
	.id		= I2C_DRIVERID_STM41T00,
	.attach_adapter	= m41t00_attach,
	.detach_client	= m41t00_detach,
};

static int __init
m41t00_init(void)
{
	return i2c_add_driver(&m41t00_driver);
}

static void __exit
m41t00_exit(void)
{
	i2c_del_driver(&m41t00_driver);
	return;
}

module_init(m41t00_init);
module_exit(m41t00_exit);

MODULE_AUTHOR("Mark A. Greer <mgreer@mvista.com>");
MODULE_DESCRIPTION("ST Microelectronics M41T00 RTC I2C Client Driver");
MODULE_LICENSE("GPL");