UPSTREAM Revert 3.9 "rtc: palmas: Add RTC driver Palmas series PMIC"
[linux-3.10.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_VERSION "0.2"
21
22 /*
23  * register indices
24  */
25 #define MAX6900_REG_SC                  0       /* seconds      00-59 */
26 #define MAX6900_REG_MN                  1       /* minutes      00-59 */
27 #define MAX6900_REG_HR                  2       /* hours        00-23 */
28 #define MAX6900_REG_DT                  3       /* day of month 00-31 */
29 #define MAX6900_REG_MO                  4       /* month        01-12 */
30 #define MAX6900_REG_DW                  5       /* day of week   1-7  */
31 #define MAX6900_REG_YR                  6       /* year         00-99 */
32 #define MAX6900_REG_CT                  7       /* control */
33                                                 /* register 8 is undocumented */
34 #define MAX6900_REG_CENTURY             9       /* century */
35 #define MAX6900_REG_LEN                 10
36
37 #define MAX6900_BURST_LEN               8       /* can burst r/w first 8 regs */
38
39 #define MAX6900_REG_CT_WP               (1 << 7)        /* Write Protect */
40
41 /*
42  * register read/write commands
43  */
44 #define MAX6900_REG_CONTROL_WRITE       0x8e
45 #define MAX6900_REG_CENTURY_WRITE       0x92
46 #define MAX6900_REG_CENTURY_READ        0x93
47 #define MAX6900_REG_RESERVED_READ       0x96
48 #define MAX6900_REG_BURST_WRITE         0xbe
49 #define MAX6900_REG_BURST_READ          0xbf
50
51 #define MAX6900_IDLE_TIME_AFTER_WRITE   3       /* specification says 2.5 mS */
52
53 static struct i2c_driver max6900_driver;
54
55 static int max6900_i2c_read_regs(struct i2c_client *client, u8 *buf)
56 {
57         u8 reg_burst_read[1] = { MAX6900_REG_BURST_READ };
58         u8 reg_century_read[1] = { MAX6900_REG_CENTURY_READ };
59         struct i2c_msg msgs[4] = {
60                 {
61                  .addr = client->addr,
62                  .flags = 0,    /* write */
63                  .len = sizeof(reg_burst_read),
64                  .buf = reg_burst_read}
65                 ,
66                 {
67                  .addr = client->addr,
68                  .flags = I2C_M_RD,
69                  .len = MAX6900_BURST_LEN,
70                  .buf = buf}
71                 ,
72                 {
73                  .addr = client->addr,
74                  .flags = 0,    /* write */
75                  .len = sizeof(reg_century_read),
76                  .buf = reg_century_read}
77                 ,
78                 {
79                  .addr = client->addr,
80                  .flags = I2C_M_RD,
81                  .len = sizeof(buf[MAX6900_REG_CENTURY]),
82                  .buf = &buf[MAX6900_REG_CENTURY]
83                  }
84         };
85         int rc;
86
87         rc = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
88         if (rc != ARRAY_SIZE(msgs)) {
89                 dev_err(&client->dev, "%s: register read failed\n", __func__);
90                 return -EIO;
91         }
92         return 0;
93 }
94
95 static int max6900_i2c_write_regs(struct i2c_client *client, u8 const *buf)
96 {
97         u8 i2c_century_buf[1 + 1] = { MAX6900_REG_CENTURY_WRITE };
98         struct i2c_msg century_msgs[1] = {
99                 {
100                  .addr = client->addr,
101                  .flags = 0,    /* write */
102                  .len = sizeof(i2c_century_buf),
103                  .buf = i2c_century_buf}
104         };
105         u8 i2c_burst_buf[MAX6900_BURST_LEN + 1] = { MAX6900_REG_BURST_WRITE };
106         struct i2c_msg burst_msgs[1] = {
107                 {
108                  .addr = client->addr,
109                  .flags = 0,    /* write */
110                  .len = sizeof(i2c_burst_buf),
111                  .buf = i2c_burst_buf}
112         };
113         int rc;
114
115         /*
116          * We have to make separate calls to i2c_transfer because of
117          * the need to delay after each write to the chip.  Also,
118          * we write the century byte first, since we set the write-protect
119          * bit as part of the burst write.
120          */
121         i2c_century_buf[1] = buf[MAX6900_REG_CENTURY];
122
123         rc = i2c_transfer(client->adapter, century_msgs,
124                           ARRAY_SIZE(century_msgs));
125         if (rc != ARRAY_SIZE(century_msgs))
126                 goto write_failed;
127
128         msleep(MAX6900_IDLE_TIME_AFTER_WRITE);
129
130         memcpy(&i2c_burst_buf[1], buf, MAX6900_BURST_LEN);
131
132         rc = i2c_transfer(client->adapter, burst_msgs, ARRAY_SIZE(burst_msgs));
133         if (rc != ARRAY_SIZE(burst_msgs))
134                 goto write_failed;
135         msleep(MAX6900_IDLE_TIME_AFTER_WRITE);
136
137         return 0;
138
139  write_failed:
140         dev_err(&client->dev, "%s: register write failed\n", __func__);
141         return -EIO;
142 }
143
144 static int max6900_i2c_read_time(struct i2c_client *client, struct rtc_time *tm)
145 {
146         int rc;
147         u8 regs[MAX6900_REG_LEN];
148
149         rc = max6900_i2c_read_regs(client, regs);
150         if (rc < 0)
151                 return rc;
152
153         tm->tm_sec = bcd2bin(regs[MAX6900_REG_SC]);
154         tm->tm_min = bcd2bin(regs[MAX6900_REG_MN]);
155         tm->tm_hour = bcd2bin(regs[MAX6900_REG_HR] & 0x3f);
156         tm->tm_mday = bcd2bin(regs[MAX6900_REG_DT]);
157         tm->tm_mon = bcd2bin(regs[MAX6900_REG_MO]) - 1;
158         tm->tm_year = bcd2bin(regs[MAX6900_REG_YR]) +
159                       bcd2bin(regs[MAX6900_REG_CENTURY]) * 100 - 1900;
160         tm->tm_wday = bcd2bin(regs[MAX6900_REG_DW]);
161
162         return rtc_valid_tm(tm);
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                         __func__);
172                 return -EIO;
173         }
174         return 0;
175 }
176
177 static int
178 max6900_i2c_set_time(struct i2c_client *client, 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_DW] = bin2bcd(tm->tm_wday);
193         regs[MAX6900_REG_YR] = bin2bcd(tm->tm_year % 100);
194         regs[MAX6900_REG_CENTURY] = bin2bcd((tm->tm_year + 1900) / 100);
195         /* set write protect */
196         regs[MAX6900_REG_CT] = MAX6900_REG_CT_WP;
197
198         rc = max6900_i2c_write_regs(client, regs);
199         if (rc < 0)
200                 return rc;
201
202         return 0;
203 }
204
205 static int max6900_rtc_read_time(struct device *dev, struct rtc_time *tm)
206 {
207         return max6900_i2c_read_time(to_i2c_client(dev), tm);
208 }
209
210 static int max6900_rtc_set_time(struct device *dev, struct rtc_time *tm)
211 {
212         return max6900_i2c_set_time(to_i2c_client(dev), tm);
213 }
214
215 static int max6900_remove(struct i2c_client *client)
216 {
217         return 0;
218 }
219
220 static const struct rtc_class_ops max6900_rtc_ops = {
221         .read_time = max6900_rtc_read_time,
222         .set_time = max6900_rtc_set_time,
223 };
224
225 static int
226 max6900_probe(struct i2c_client *client, const struct i2c_device_id *id)
227 {
228         struct rtc_device *rtc;
229
230         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
231                 return -ENODEV;
232
233         dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
234
235         rtc = devm_rtc_device_register(&client->dev, max6900_driver.driver.name,
236                                         &max6900_rtc_ops, THIS_MODULE);
237         if (IS_ERR(rtc))
238                 return PTR_ERR(rtc);
239
240         i2c_set_clientdata(client, rtc);
241
242         return 0;
243 }
244
245 static struct i2c_device_id max6900_id[] = {
246         { "max6900", 0 },
247         { }
248 };
249
250 static struct i2c_driver max6900_driver = {
251         .driver = {
252                    .name = "rtc-max6900",
253                    },
254         .probe = max6900_probe,
255         .remove = max6900_remove,
256         .id_table = max6900_id,
257 };
258
259 module_i2c_driver(max6900_driver);
260
261 MODULE_DESCRIPTION("Maxim MAX6900 RTC driver");
262 MODULE_AUTHOR("Dale Farnsworth <dale@farnsworth.org>");
263 MODULE_LICENSE("GPL");
264 MODULE_VERSION(DRV_VERSION);