eee4ee5bb75af15a9688072b46616b80d5949857
[linux-2.6.git] / drivers / rtc / rtc-max6900.c
1 /*
2  * rtc class driver for the Maxim MAX6900 chip
3  *
4  * Author: Dale Farnsworth <dale@farnsworth.org>
5  *
6  * based on previously existing rtc class drivers
7  *
8  * 2007 (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 #include <linux/module.h>
15 #include <linux/i2c.h>
16 #include <linux/bcd.h>
17 #include <linux/rtc.h>
18 #include <linux/delay.h>
19
20 #define DRV_NAME "max6900"
21 #define DRV_VERSION "0.1"
22
23 /*
24  * register indices
25  */
26 #define MAX6900_REG_SC                  0       /* seconds      00-59 */
27 #define MAX6900_REG_MN                  1       /* minutes      00-59 */
28 #define MAX6900_REG_HR                  2       /* hours        00-23 */
29 #define MAX6900_REG_DT                  3       /* day of month 00-31 */
30 #define MAX6900_REG_MO                  4       /* month        01-12 */
31 #define MAX6900_REG_DW                  5       /* day of week   1-7  */
32 #define MAX6900_REG_YR                  6       /* year         00-99 */
33 #define MAX6900_REG_CT                  7       /* control */
34 #define MAX6900_REG_LEN                 8
35
36 #define MAX6900_REG_CT_WP               (1 << 7)        /* Write Protect */
37
38 /*
39  * register read/write commands
40  */
41 #define MAX6900_REG_CONTROL_WRITE       0x8e
42 #define MAX6900_REG_BURST_READ          0xbf
43 #define MAX6900_REG_BURST_WRITE         0xbe
44 #define MAX6900_REG_RESERVED_READ       0x96
45
46 #define MAX6900_IDLE_TIME_AFTER_WRITE   3       /* specification says 2.5 mS */
47
48 #define MAX6900_I2C_ADDR                0xa0
49
50 static unsigned short normal_i2c[] = {
51         MAX6900_I2C_ADDR >> 1,
52         I2C_CLIENT_END
53 };
54
55 I2C_CLIENT_INSMOD;                      /* defines addr_data */
56
57 static int max6900_probe(struct i2c_adapter *adapter, int addr, int kind);
58
59 static int max6900_i2c_read_regs(struct i2c_client *client, u8 *buf)
60 {
61         u8 reg_addr[1] = { MAX6900_REG_BURST_READ };
62         struct i2c_msg msgs[2] = {
63                 {
64                         .addr   = client->addr,
65                         .flags  = 0, /* write */
66                         .len    = sizeof(reg_addr),
67                         .buf    = reg_addr
68                 },
69                 {
70                         .addr   = client->addr,
71                         .flags  = I2C_M_RD,
72                         .len    = MAX6900_REG_LEN,
73                         .buf    = buf
74                 }
75         };
76         int rc;
77
78         rc = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
79         if (rc != ARRAY_SIZE(msgs)) {
80                 dev_err(&client->dev, "%s: register read failed\n",
81                         __FUNCTION__);
82                 return -EIO;
83         }
84         return 0;
85 }
86
87 static int max6900_i2c_write_regs(struct i2c_client *client, u8 const *buf)
88 {
89         u8 i2c_buf[MAX6900_REG_LEN + 1] = { MAX6900_REG_BURST_WRITE };
90         struct i2c_msg msgs[1] = {
91                 {
92                         .addr   = client->addr,
93                         .flags  = 0, /* write */
94                         .len    = MAX6900_REG_LEN + 1,
95                         .buf    = i2c_buf
96                 }
97         };
98         int rc;
99
100         memcpy(&i2c_buf[1], buf, MAX6900_REG_LEN);
101
102         rc = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
103         if (rc != ARRAY_SIZE(msgs)) {
104                 dev_err(&client->dev, "%s: register write failed\n",
105                         __FUNCTION__);
106                 return -EIO;
107         }
108         msleep(MAX6900_IDLE_TIME_AFTER_WRITE);
109         return 0;
110 }
111
112 static int max6900_i2c_validate_client(struct i2c_client *client)
113 {
114         u8 regs[MAX6900_REG_LEN];
115         u8 zero_mask[MAX6900_REG_LEN] = {
116                 0x80,   /* seconds */
117                 0x80,   /* minutes */
118                 0x40,   /* hours */
119                 0xc0,   /* day of month */
120                 0xe0,   /* month */
121                 0xf8,   /* day of week */
122                 0x00,   /* year */
123                 0x7f,   /* control */
124         };
125         int i;
126         int rc;
127         int reserved;
128
129         reserved = i2c_smbus_read_byte_data(client, MAX6900_REG_RESERVED_READ);
130         if (reserved != 0x07)
131                 return -ENODEV;
132
133         rc = max6900_i2c_read_regs(client, regs);
134         if (rc < 0)
135                 return rc;
136
137         for (i = 0; i < MAX6900_REG_LEN; ++i) {
138                 if (regs[i] & zero_mask[i])
139                         return -ENODEV;
140         }
141
142         return 0;
143 }
144
145 static int max6900_i2c_read_time(struct i2c_client *client, struct rtc_time *tm)
146 {
147         int rc;
148         u8 regs[MAX6900_REG_LEN];
149
150         rc = max6900_i2c_read_regs(client, regs);
151         if (rc < 0)
152                 return rc;
153
154         tm->tm_sec = BCD2BIN(regs[MAX6900_REG_SC]);
155         tm->tm_min = BCD2BIN(regs[MAX6900_REG_MN]);
156         tm->tm_hour = BCD2BIN(regs[MAX6900_REG_HR] & 0x3f);
157         tm->tm_mday = BCD2BIN(regs[MAX6900_REG_DT]);
158         tm->tm_mon = BCD2BIN(regs[MAX6900_REG_MO]) - 1;
159         tm->tm_year = BCD2BIN(regs[MAX6900_REG_YR]) + 100;
160         tm->tm_wday = BCD2BIN(regs[MAX6900_REG_DW]);
161
162         return 0;
163 }
164
165 static int max6900_i2c_clear_write_protect(struct i2c_client *client)
166 {
167         int rc;
168         rc = i2c_smbus_write_byte_data (client, MAX6900_REG_CONTROL_WRITE, 0);
169         if (rc < 0) {
170                 dev_err(&client->dev, "%s: control register write failed\n",
171                         __FUNCTION__);
172                 return -EIO;
173         }
174         return 0;
175 }
176
177 static int max6900_i2c_set_time(struct i2c_client *client,
178                                 struct rtc_time const *tm)
179 {
180         u8 regs[MAX6900_REG_LEN];
181         int rc;
182
183         rc = max6900_i2c_clear_write_protect(client);
184         if (rc < 0)
185                 return rc;
186
187         regs[MAX6900_REG_SC] = BIN2BCD(tm->tm_sec);
188         regs[MAX6900_REG_MN] = BIN2BCD(tm->tm_min);
189         regs[MAX6900_REG_HR] = BIN2BCD(tm->tm_hour);
190         regs[MAX6900_REG_DT] = BIN2BCD(tm->tm_mday);
191         regs[MAX6900_REG_MO] = BIN2BCD(tm->tm_mon + 1);
192         regs[MAX6900_REG_YR] = BIN2BCD(tm->tm_year - 100);
193         regs[MAX6900_REG_DW] = BIN2BCD(tm->tm_wday);
194         regs[MAX6900_REG_CT] = MAX6900_REG_CT_WP;       /* set write protect */
195
196         rc = max6900_i2c_write_regs(client, regs);
197         if (rc < 0)
198                 return rc;
199
200         return 0;
201 }
202
203 static int max6900_rtc_read_time(struct device *dev, struct rtc_time *tm)
204 {
205         return max6900_i2c_read_time(to_i2c_client(dev), tm);
206 }
207
208 static int max6900_rtc_set_time(struct device *dev, struct rtc_time *tm)
209 {
210         return max6900_i2c_set_time(to_i2c_client(dev), tm);
211 }
212
213 static int max6900_attach_adapter(struct i2c_adapter *adapter)
214 {
215         return i2c_probe(adapter, &addr_data, max6900_probe);
216 }
217
218 static int max6900_detach_client(struct i2c_client *client)
219 {
220         struct rtc_device *const rtc = i2c_get_clientdata(client);
221
222         if (rtc)
223                 rtc_device_unregister(rtc);
224
225         return i2c_detach_client(client);
226 }
227
228 static struct i2c_driver max6900_driver = {
229         .driver         = {
230                 .name   = DRV_NAME,
231         },
232         .id             = I2C_DRIVERID_MAX6900,
233         .attach_adapter = max6900_attach_adapter,
234         .detach_client  = max6900_detach_client,
235 };
236
237 static const struct rtc_class_ops max6900_rtc_ops = {
238         .read_time      = max6900_rtc_read_time,
239         .set_time       = max6900_rtc_set_time,
240 };
241
242 static int max6900_probe(struct i2c_adapter *adapter, int addr, int kind)
243 {
244         int rc = 0;
245         struct i2c_client *client = NULL;
246         struct rtc_device *rtc = NULL;
247
248         if (!i2c_check_functionality(adapter, I2C_FUNC_I2C)) {
249                 rc = -ENODEV;
250                 goto failout;
251         }
252
253         client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
254         if (client == NULL) {
255                 rc = -ENOMEM;
256                 goto failout;
257         }
258
259         client->addr = addr;
260         client->adapter = adapter;
261         client->driver = &max6900_driver;
262         strlcpy(client->name, DRV_NAME, I2C_NAME_SIZE);
263
264         if (kind < 0) {
265                 rc = max6900_i2c_validate_client(client);
266                 if (rc < 0)
267                         goto failout;
268         }
269
270         rc = i2c_attach_client(client);
271         if (rc < 0)
272                 goto failout;
273
274         dev_info(&client->dev,
275                  "chip found, driver version " DRV_VERSION "\n");
276
277         rtc = rtc_device_register(max6900_driver.driver.name,
278                                   &client->dev,
279                                   &max6900_rtc_ops, THIS_MODULE);
280         if (IS_ERR(rtc)) {
281                 rc = PTR_ERR(rtc);
282                 goto failout_detach;
283         }
284
285         i2c_set_clientdata(client, rtc);
286
287         return 0;
288
289 failout_detach:
290         i2c_detach_client(client);
291 failout:
292         kfree(client);
293         return rc;
294 }
295
296 static int __init max6900_init(void)
297 {
298         return i2c_add_driver(&max6900_driver);
299 }
300
301 static void __exit max6900_exit(void)
302 {
303         i2c_del_driver(&max6900_driver);
304 }
305
306 MODULE_DESCRIPTION("Maxim MAX6900 RTC driver");
307 MODULE_LICENSE("GPL");
308 MODULE_VERSION(DRV_VERSION);
309
310 module_init(max6900_init);
311 module_exit(max6900_exit);