3df309ae44a6e9f30da0f66698a73825bbc7217f
[linux-2.6.git] / drivers / i2c / chips / m41t00.c
1 /*
2  * drivers/i2c/chips/m41t00.c
3  *
4  * I2C client/driver for the ST M41T00 Real-Time Clock chip.
5  *
6  * Author: Mark A. Greer <mgreer@mvista.com>
7  *
8  * 2005 (c) MontaVista Software, Inc. This file is licensed under
9  * the terms of the GNU General Public License version 2. This program
10  * is licensed "as is" without any warranty of any kind, whether express
11  * or implied.
12  */
13 /*
14  * This i2c client/driver wedges between the drivers/char/genrtc.c RTC
15  * interface and the SMBus interface of the i2c subsystem.
16  * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
17  * recommened in .../Documentation/i2c/writing-clients section
18  * "Sending and receiving", using SMBus level communication is preferred.
19  */
20
21 #include <linux/kernel.h>
22 #include <linux/module.h>
23 #include <linux/interrupt.h>
24 #include <linux/i2c.h>
25 #include <linux/rtc.h>
26 #include <linux/bcd.h>
27
28 #include <asm/time.h>
29 #include <asm/rtc.h>
30
31 #define M41T00_DRV_NAME         "m41t00"
32
33 static DECLARE_MUTEX(m41t00_mutex);
34
35 static struct i2c_driver m41t00_driver;
36 static struct i2c_client *save_client;
37
38 static unsigned short ignore[] = { I2C_CLIENT_END };
39 static unsigned short normal_addr[] = { 0x68, I2C_CLIENT_END };
40
41 static struct i2c_client_address_data addr_data = {
42         .normal_i2c             = normal_addr,
43         .probe                  = ignore,
44         .ignore                 = ignore,
45 };
46
47 ulong
48 m41t00_get_rtc_time(void)
49 {
50         s32     sec, min, hour, day, mon, year;
51         s32     sec1, min1, hour1, day1, mon1, year1;
52         ulong   limit = 10;
53
54         sec = min = hour = day = mon = year = 0;
55         sec1 = min1 = hour1 = day1 = mon1 = year1 = 0;
56
57         down(&m41t00_mutex);
58         do {
59                 if (((sec = i2c_smbus_read_byte_data(save_client, 0)) >= 0)
60                         && ((min = i2c_smbus_read_byte_data(save_client, 1))
61                                 >= 0)
62                         && ((hour = i2c_smbus_read_byte_data(save_client, 2))
63                                 >= 0)
64                         && ((day = i2c_smbus_read_byte_data(save_client, 4))
65                                 >= 0)
66                         && ((mon = i2c_smbus_read_byte_data(save_client, 5))
67                                 >= 0)
68                         && ((year = i2c_smbus_read_byte_data(save_client, 6))
69                                 >= 0)
70                         && ((sec == sec1) && (min == min1) && (hour == hour1)
71                                 && (day == day1) && (mon == mon1)
72                                 && (year == year1)))
73
74                                 break;
75
76                 sec1 = sec;
77                 min1 = min;
78                 hour1 = hour;
79                 day1 = day;
80                 mon1 = mon;
81                 year1 = year;
82         } while (--limit > 0);
83         up(&m41t00_mutex);
84
85         if (limit == 0) {
86                 dev_warn(&save_client->dev,
87                         "m41t00: can't read rtc chip\n");
88                 sec = min = hour = day = mon = year = 0;
89         }
90
91         sec &= 0x7f;
92         min &= 0x7f;
93         hour &= 0x3f;
94         day &= 0x3f;
95         mon &= 0x1f;
96         year &= 0xff;
97
98         BCD_TO_BIN(sec);
99         BCD_TO_BIN(min);
100         BCD_TO_BIN(hour);
101         BCD_TO_BIN(day);
102         BCD_TO_BIN(mon);
103         BCD_TO_BIN(year);
104
105         year += 1900;
106         if (year < 1970)
107                 year += 100;
108
109         return mktime(year, mon, day, hour, min, sec);
110 }
111
112 static void
113 m41t00_set_tlet(ulong arg)
114 {
115         struct rtc_time tm;
116         ulong   nowtime = *(ulong *)arg;
117
118         to_tm(nowtime, &tm);
119         tm.tm_year = (tm.tm_year - 1900) % 100;
120
121         BIN_TO_BCD(tm.tm_sec);
122         BIN_TO_BCD(tm.tm_min);
123         BIN_TO_BCD(tm.tm_hour);
124         BIN_TO_BCD(tm.tm_mon);
125         BIN_TO_BCD(tm.tm_mday);
126         BIN_TO_BCD(tm.tm_year);
127
128         down(&m41t00_mutex);
129         if ((i2c_smbus_write_byte_data(save_client, 0, tm.tm_sec & 0x7f) < 0)
130                 || (i2c_smbus_write_byte_data(save_client, 1, tm.tm_min & 0x7f)
131                         < 0)
132                 || (i2c_smbus_write_byte_data(save_client, 2, tm.tm_hour & 0x7f)
133                         < 0)
134                 || (i2c_smbus_write_byte_data(save_client, 4, tm.tm_mday & 0x7f)
135                         < 0)
136                 || (i2c_smbus_write_byte_data(save_client, 5, tm.tm_mon & 0x7f)
137                         < 0)
138                 || (i2c_smbus_write_byte_data(save_client, 6, tm.tm_year & 0x7f)
139                         < 0))
140
141                 dev_warn(&save_client->dev,"m41t00: can't write to rtc chip\n");
142
143         up(&m41t00_mutex);
144         return;
145 }
146
147 static ulong    new_time;
148
149 DECLARE_TASKLET_DISABLED(m41t00_tasklet, m41t00_set_tlet, (ulong)&new_time);
150
151 int
152 m41t00_set_rtc_time(ulong nowtime)
153 {
154         new_time = nowtime;
155
156         if (in_interrupt())
157                 tasklet_schedule(&m41t00_tasklet);
158         else
159                 m41t00_set_tlet((ulong)&new_time);
160
161         return 0;
162 }
163
164 /*
165  *****************************************************************************
166  *
167  *      Driver Interface
168  *
169  *****************************************************************************
170  */
171 static int
172 m41t00_probe(struct i2c_adapter *adap, int addr, int kind)
173 {
174         struct i2c_client *client;
175         int rc;
176
177         client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
178         if (!client)
179                 return -ENOMEM;
180
181         strncpy(client->name, M41T00_DRV_NAME, I2C_NAME_SIZE);
182         client->addr = addr;
183         client->adapter = adap;
184         client->driver = &m41t00_driver;
185
186         if ((rc = i2c_attach_client(client)) != 0) {
187                 kfree(client);
188                 return rc;
189         }
190
191         save_client = client;
192         return 0;
193 }
194
195 static int
196 m41t00_attach(struct i2c_adapter *adap)
197 {
198         return i2c_probe(adap, &addr_data, m41t00_probe);
199 }
200
201 static int
202 m41t00_detach(struct i2c_client *client)
203 {
204         int     rc;
205
206         if ((rc = i2c_detach_client(client)) == 0) {
207                 kfree(client);
208                 tasklet_kill(&m41t00_tasklet);
209         }
210         return rc;
211 }
212
213 static struct i2c_driver m41t00_driver = {
214         .owner          = THIS_MODULE,
215         .name           = M41T00_DRV_NAME,
216         .id             = I2C_DRIVERID_STM41T00,
217         .flags          = I2C_DF_NOTIFY,
218         .attach_adapter = m41t00_attach,
219         .detach_client  = m41t00_detach,
220 };
221
222 static int __init
223 m41t00_init(void)
224 {
225         return i2c_add_driver(&m41t00_driver);
226 }
227
228 static void __exit
229 m41t00_exit(void)
230 {
231         i2c_del_driver(&m41t00_driver);
232         return;
233 }
234
235 module_init(m41t00_init);
236 module_exit(m41t00_exit);
237
238 MODULE_AUTHOR("Mark A. Greer <mgreer@mvista.com>");
239 MODULE_DESCRIPTION("ST Microelectronics M41T00 RTC I2C Client Driver");
240 MODULE_LICENSE("GPL");