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aa5bd7e9 DF |
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 | ||
6fd5c03f | 20 | #define DRV_VERSION "0.2" |
aa5bd7e9 DF |
21 | |
22 | /* | |
23 | * register indices | |
24 | */ | |
6fd5c03f AZ |
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 */ | |
aa5bd7e9 | 32 | #define MAX6900_REG_CT 7 /* control */ |
8a2601f6 DF |
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 */ | |
aa5bd7e9 DF |
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 | |
8a2601f6 DF |
45 | #define MAX6900_REG_CENTURY_WRITE 0x92 |
46 | #define MAX6900_REG_CENTURY_READ 0x93 | |
aa5bd7e9 | 47 | #define MAX6900_REG_RESERVED_READ 0x96 |
8a2601f6 DF |
48 | #define MAX6900_REG_BURST_WRITE 0xbe |
49 | #define MAX6900_REG_BURST_READ 0xbf | |
aa5bd7e9 DF |
50 | |
51 | #define MAX6900_IDLE_TIME_AFTER_WRITE 3 /* specification says 2.5 mS */ | |
52 | ||
6fd5c03f | 53 | static struct i2c_driver max6900_driver; |
aa5bd7e9 DF |
54 | |
55 | static int max6900_i2c_read_regs(struct i2c_client *client, u8 *buf) | |
56 | { | |
8a2601f6 DF |
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] = { | |
aa5bd7e9 | 60 | { |
6fd5c03f AZ |
61 | .addr = client->addr, |
62 | .flags = 0, /* write */ | |
63 | .len = sizeof(reg_burst_read), | |
64 | .buf = reg_burst_read} | |
65 | , | |
aa5bd7e9 | 66 | { |
6fd5c03f AZ |
67 | .addr = client->addr, |
68 | .flags = I2C_M_RD, | |
69 | .len = MAX6900_BURST_LEN, | |
70 | .buf = buf} | |
71 | , | |
8a2601f6 | 72 | { |
6fd5c03f AZ |
73 | .addr = client->addr, |
74 | .flags = 0, /* write */ | |
75 | .len = sizeof(reg_century_read), | |
76 | .buf = reg_century_read} | |
77 | , | |
8a2601f6 | 78 | { |
6fd5c03f AZ |
79 | .addr = client->addr, |
80 | .flags = I2C_M_RD, | |
81 | .len = sizeof(buf[MAX6900_REG_CENTURY]), | |
82 | .buf = &buf[MAX6900_REG_CENTURY] | |
83 | } | |
aa5bd7e9 DF |
84 | }; |
85 | int rc; | |
86 | ||
87 | rc = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs)); | |
88 | if (rc != ARRAY_SIZE(msgs)) { | |
6fd5c03f | 89 | dev_err(&client->dev, "%s: register read failed\n", __func__); |
aa5bd7e9 DF |
90 | return -EIO; |
91 | } | |
92 | return 0; | |
93 | } | |
94 | ||
95 | static int max6900_i2c_write_regs(struct i2c_client *client, u8 const *buf) | |
96 | { | |
8a2601f6 DF |
97 | u8 i2c_century_buf[1 + 1] = { MAX6900_REG_CENTURY_WRITE }; |
98 | struct i2c_msg century_msgs[1] = { | |
aa5bd7e9 | 99 | { |
6fd5c03f AZ |
100 | .addr = client->addr, |
101 | .flags = 0, /* write */ | |
102 | .len = sizeof(i2c_century_buf), | |
103 | .buf = i2c_century_buf} | |
8a2601f6 DF |
104 | }; |
105 | u8 i2c_burst_buf[MAX6900_BURST_LEN + 1] = { MAX6900_REG_BURST_WRITE }; | |
106 | struct i2c_msg burst_msgs[1] = { | |
107 | { | |
6fd5c03f AZ |
108 | .addr = client->addr, |
109 | .flags = 0, /* write */ | |
110 | .len = sizeof(i2c_burst_buf), | |
111 | .buf = i2c_burst_buf} | |
aa5bd7e9 DF |
112 | }; |
113 | int rc; | |
114 | ||
8a2601f6 DF |
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]; | |
6fd5c03f | 122 | |
8a2601f6 DF |
123 | rc = i2c_transfer(client->adapter, century_msgs, |
124 | ARRAY_SIZE(century_msgs)); | |
125 | if (rc != ARRAY_SIZE(century_msgs)) | |
126 | goto write_failed; | |
6fd5c03f | 127 | |
8a2601f6 | 128 | msleep(MAX6900_IDLE_TIME_AFTER_WRITE); |
aa5bd7e9 | 129 | |
8a2601f6 DF |
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; | |
aa5bd7e9 | 135 | msleep(MAX6900_IDLE_TIME_AFTER_WRITE); |
8a2601f6 | 136 | |
aa5bd7e9 | 137 | return 0; |
8a2601f6 | 138 | |
6fd5c03f AZ |
139 | write_failed: |
140 | dev_err(&client->dev, "%s: register write failed\n", __func__); | |
8a2601f6 | 141 | return -EIO; |
aa5bd7e9 DF |
142 | } |
143 | ||
aa5bd7e9 DF |
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 | ||
fe20ba70 AB |
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]); | |
aa5bd7e9 | 161 | |
c814dc13 | 162 | return rtc_valid_tm(tm); |
aa5bd7e9 DF |
163 | } |
164 | ||
165 | static int max6900_i2c_clear_write_protect(struct i2c_client *client) | |
166 | { | |
167 | int rc; | |
6fd5c03f | 168 | rc = i2c_smbus_write_byte_data(client, MAX6900_REG_CONTROL_WRITE, 0); |
aa5bd7e9 DF |
169 | if (rc < 0) { |
170 | dev_err(&client->dev, "%s: control register write failed\n", | |
2a4e2b87 | 171 | __func__); |
aa5bd7e9 DF |
172 | return -EIO; |
173 | } | |
174 | return 0; | |
175 | } | |
176 | ||
6fd5c03f AZ |
177 | static int |
178 | max6900_i2c_set_time(struct i2c_client *client, struct rtc_time const *tm) | |
aa5bd7e9 DF |
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 | ||
fe20ba70 AB |
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); | |
8a2601f6 DF |
195 | /* set write protect */ |
196 | regs[MAX6900_REG_CT] = MAX6900_REG_CT_WP; | |
aa5bd7e9 DF |
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 | ||
aa5bd7e9 | 215 | static const struct rtc_class_ops max6900_rtc_ops = { |
6fd5c03f AZ |
216 | .read_time = max6900_rtc_read_time, |
217 | .set_time = max6900_rtc_set_time, | |
aa5bd7e9 DF |
218 | }; |
219 | ||
6fd5c03f AZ |
220 | static int |
221 | max6900_probe(struct i2c_client *client, const struct i2c_device_id *id) | |
aa5bd7e9 | 222 | { |
6fd5c03f | 223 | struct rtc_device *rtc; |
aa5bd7e9 | 224 | |
6fd5c03f AZ |
225 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) |
226 | return -ENODEV; | |
aa5bd7e9 | 227 | |
6fd5c03f | 228 | dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n"); |
aa5bd7e9 | 229 | |
feb141d1 JH |
230 | rtc = devm_rtc_device_register(&client->dev, max6900_driver.driver.name, |
231 | &max6900_rtc_ops, THIS_MODULE); | |
6fd5c03f AZ |
232 | if (IS_ERR(rtc)) |
233 | return PTR_ERR(rtc); | |
aa5bd7e9 DF |
234 | |
235 | i2c_set_clientdata(client, rtc); | |
236 | ||
237 | return 0; | |
aa5bd7e9 DF |
238 | } |
239 | ||
fe102c71 AZ |
240 | static struct i2c_device_id max6900_id[] = { |
241 | { "max6900", 0 }, | |
242 | { } | |
243 | }; | |
244 | ||
6fd5c03f AZ |
245 | static struct i2c_driver max6900_driver = { |
246 | .driver = { | |
247 | .name = "rtc-max6900", | |
248 | }, | |
249 | .probe = max6900_probe, | |
fe102c71 | 250 | .id_table = max6900_id, |
6fd5c03f AZ |
251 | }; |
252 | ||
0abc9201 | 253 | module_i2c_driver(max6900_driver); |
aa5bd7e9 DF |
254 | |
255 | MODULE_DESCRIPTION("Maxim MAX6900 RTC driver"); | |
6fd5c03f | 256 | MODULE_AUTHOR("Dale Farnsworth <dale@farnsworth.org>"); |
aa5bd7e9 DF |
257 | MODULE_LICENSE("GPL"); |
258 | MODULE_VERSION(DRV_VERSION); |