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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 | ||
aa5bd7e9 DF |
20 | /* |
21 | * register indices | |
22 | */ | |
6fd5c03f AZ |
23 | #define MAX6900_REG_SC 0 /* seconds 00-59 */ |
24 | #define MAX6900_REG_MN 1 /* minutes 00-59 */ | |
25 | #define MAX6900_REG_HR 2 /* hours 00-23 */ | |
26 | #define MAX6900_REG_DT 3 /* day of month 00-31 */ | |
27 | #define MAX6900_REG_MO 4 /* month 01-12 */ | |
28 | #define MAX6900_REG_DW 5 /* day of week 1-7 */ | |
29 | #define MAX6900_REG_YR 6 /* year 00-99 */ | |
aa5bd7e9 | 30 | #define MAX6900_REG_CT 7 /* control */ |
8a2601f6 DF |
31 | /* register 8 is undocumented */ |
32 | #define MAX6900_REG_CENTURY 9 /* century */ | |
33 | #define MAX6900_REG_LEN 10 | |
34 | ||
35 | #define MAX6900_BURST_LEN 8 /* can burst r/w first 8 regs */ | |
aa5bd7e9 DF |
36 | |
37 | #define MAX6900_REG_CT_WP (1 << 7) /* Write Protect */ | |
38 | ||
39 | /* | |
40 | * register read/write commands | |
41 | */ | |
42 | #define MAX6900_REG_CONTROL_WRITE 0x8e | |
8a2601f6 DF |
43 | #define MAX6900_REG_CENTURY_WRITE 0x92 |
44 | #define MAX6900_REG_CENTURY_READ 0x93 | |
aa5bd7e9 | 45 | #define MAX6900_REG_RESERVED_READ 0x96 |
8a2601f6 DF |
46 | #define MAX6900_REG_BURST_WRITE 0xbe |
47 | #define MAX6900_REG_BURST_READ 0xbf | |
aa5bd7e9 DF |
48 | |
49 | #define MAX6900_IDLE_TIME_AFTER_WRITE 3 /* specification says 2.5 mS */ | |
50 | ||
6fd5c03f | 51 | static struct i2c_driver max6900_driver; |
aa5bd7e9 DF |
52 | |
53 | static int max6900_i2c_read_regs(struct i2c_client *client, u8 *buf) | |
54 | { | |
8a2601f6 DF |
55 | u8 reg_burst_read[1] = { MAX6900_REG_BURST_READ }; |
56 | u8 reg_century_read[1] = { MAX6900_REG_CENTURY_READ }; | |
57 | struct i2c_msg msgs[4] = { | |
aa5bd7e9 | 58 | { |
6fd5c03f AZ |
59 | .addr = client->addr, |
60 | .flags = 0, /* write */ | |
61 | .len = sizeof(reg_burst_read), | |
62 | .buf = reg_burst_read} | |
63 | , | |
aa5bd7e9 | 64 | { |
6fd5c03f AZ |
65 | .addr = client->addr, |
66 | .flags = I2C_M_RD, | |
67 | .len = MAX6900_BURST_LEN, | |
68 | .buf = buf} | |
69 | , | |
8a2601f6 | 70 | { |
6fd5c03f AZ |
71 | .addr = client->addr, |
72 | .flags = 0, /* write */ | |
73 | .len = sizeof(reg_century_read), | |
74 | .buf = reg_century_read} | |
75 | , | |
8a2601f6 | 76 | { |
6fd5c03f AZ |
77 | .addr = client->addr, |
78 | .flags = I2C_M_RD, | |
79 | .len = sizeof(buf[MAX6900_REG_CENTURY]), | |
80 | .buf = &buf[MAX6900_REG_CENTURY] | |
81 | } | |
aa5bd7e9 DF |
82 | }; |
83 | int rc; | |
84 | ||
85 | rc = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs)); | |
86 | if (rc != ARRAY_SIZE(msgs)) { | |
6fd5c03f | 87 | dev_err(&client->dev, "%s: register read failed\n", __func__); |
aa5bd7e9 DF |
88 | return -EIO; |
89 | } | |
90 | return 0; | |
91 | } | |
92 | ||
93 | static int max6900_i2c_write_regs(struct i2c_client *client, u8 const *buf) | |
94 | { | |
8a2601f6 DF |
95 | u8 i2c_century_buf[1 + 1] = { MAX6900_REG_CENTURY_WRITE }; |
96 | struct i2c_msg century_msgs[1] = { | |
aa5bd7e9 | 97 | { |
6fd5c03f AZ |
98 | .addr = client->addr, |
99 | .flags = 0, /* write */ | |
100 | .len = sizeof(i2c_century_buf), | |
101 | .buf = i2c_century_buf} | |
8a2601f6 DF |
102 | }; |
103 | u8 i2c_burst_buf[MAX6900_BURST_LEN + 1] = { MAX6900_REG_BURST_WRITE }; | |
104 | struct i2c_msg burst_msgs[1] = { | |
105 | { | |
6fd5c03f AZ |
106 | .addr = client->addr, |
107 | .flags = 0, /* write */ | |
108 | .len = sizeof(i2c_burst_buf), | |
109 | .buf = i2c_burst_buf} | |
aa5bd7e9 DF |
110 | }; |
111 | int rc; | |
112 | ||
8a2601f6 DF |
113 | /* |
114 | * We have to make separate calls to i2c_transfer because of | |
115 | * the need to delay after each write to the chip. Also, | |
116 | * we write the century byte first, since we set the write-protect | |
117 | * bit as part of the burst write. | |
118 | */ | |
119 | i2c_century_buf[1] = buf[MAX6900_REG_CENTURY]; | |
6fd5c03f | 120 | |
8a2601f6 DF |
121 | rc = i2c_transfer(client->adapter, century_msgs, |
122 | ARRAY_SIZE(century_msgs)); | |
123 | if (rc != ARRAY_SIZE(century_msgs)) | |
124 | goto write_failed; | |
6fd5c03f | 125 | |
8a2601f6 | 126 | msleep(MAX6900_IDLE_TIME_AFTER_WRITE); |
aa5bd7e9 | 127 | |
8a2601f6 DF |
128 | memcpy(&i2c_burst_buf[1], buf, MAX6900_BURST_LEN); |
129 | ||
130 | rc = i2c_transfer(client->adapter, burst_msgs, ARRAY_SIZE(burst_msgs)); | |
131 | if (rc != ARRAY_SIZE(burst_msgs)) | |
132 | goto write_failed; | |
aa5bd7e9 | 133 | msleep(MAX6900_IDLE_TIME_AFTER_WRITE); |
8a2601f6 | 134 | |
aa5bd7e9 | 135 | return 0; |
8a2601f6 | 136 | |
6fd5c03f AZ |
137 | write_failed: |
138 | dev_err(&client->dev, "%s: register write failed\n", __func__); | |
8a2601f6 | 139 | return -EIO; |
aa5bd7e9 DF |
140 | } |
141 | ||
859a6ddb | 142 | static int max6900_rtc_read_time(struct device *dev, struct rtc_time *tm) |
aa5bd7e9 | 143 | { |
859a6ddb | 144 | struct i2c_client *client = to_i2c_client(dev); |
aa5bd7e9 DF |
145 | int rc; |
146 | u8 regs[MAX6900_REG_LEN]; | |
147 | ||
148 | rc = max6900_i2c_read_regs(client, regs); | |
149 | if (rc < 0) | |
150 | return rc; | |
151 | ||
fe20ba70 AB |
152 | tm->tm_sec = bcd2bin(regs[MAX6900_REG_SC]); |
153 | tm->tm_min = bcd2bin(regs[MAX6900_REG_MN]); | |
154 | tm->tm_hour = bcd2bin(regs[MAX6900_REG_HR] & 0x3f); | |
155 | tm->tm_mday = bcd2bin(regs[MAX6900_REG_DT]); | |
156 | tm->tm_mon = bcd2bin(regs[MAX6900_REG_MO]) - 1; | |
157 | tm->tm_year = bcd2bin(regs[MAX6900_REG_YR]) + | |
158 | bcd2bin(regs[MAX6900_REG_CENTURY]) * 100 - 1900; | |
159 | tm->tm_wday = bcd2bin(regs[MAX6900_REG_DW]); | |
aa5bd7e9 | 160 | |
ceed43f7 | 161 | return 0; |
aa5bd7e9 DF |
162 | } |
163 | ||
164 | static int max6900_i2c_clear_write_protect(struct i2c_client *client) | |
165 | { | |
f16189ac | 166 | return i2c_smbus_write_byte_data(client, MAX6900_REG_CONTROL_WRITE, 0); |
aa5bd7e9 DF |
167 | } |
168 | ||
859a6ddb | 169 | static int max6900_rtc_set_time(struct device *dev, struct rtc_time *tm) |
aa5bd7e9 | 170 | { |
859a6ddb | 171 | struct i2c_client *client = to_i2c_client(dev); |
aa5bd7e9 DF |
172 | u8 regs[MAX6900_REG_LEN]; |
173 | int rc; | |
174 | ||
175 | rc = max6900_i2c_clear_write_protect(client); | |
176 | if (rc < 0) | |
177 | return rc; | |
178 | ||
fe20ba70 AB |
179 | regs[MAX6900_REG_SC] = bin2bcd(tm->tm_sec); |
180 | regs[MAX6900_REG_MN] = bin2bcd(tm->tm_min); | |
181 | regs[MAX6900_REG_HR] = bin2bcd(tm->tm_hour); | |
182 | regs[MAX6900_REG_DT] = bin2bcd(tm->tm_mday); | |
183 | regs[MAX6900_REG_MO] = bin2bcd(tm->tm_mon + 1); | |
184 | regs[MAX6900_REG_DW] = bin2bcd(tm->tm_wday); | |
185 | regs[MAX6900_REG_YR] = bin2bcd(tm->tm_year % 100); | |
186 | regs[MAX6900_REG_CENTURY] = bin2bcd((tm->tm_year + 1900) / 100); | |
8a2601f6 DF |
187 | /* set write protect */ |
188 | regs[MAX6900_REG_CT] = MAX6900_REG_CT_WP; | |
aa5bd7e9 DF |
189 | |
190 | rc = max6900_i2c_write_regs(client, regs); | |
191 | if (rc < 0) | |
192 | return rc; | |
193 | ||
194 | return 0; | |
195 | } | |
196 | ||
aa5bd7e9 | 197 | static const struct rtc_class_ops max6900_rtc_ops = { |
6fd5c03f AZ |
198 | .read_time = max6900_rtc_read_time, |
199 | .set_time = max6900_rtc_set_time, | |
aa5bd7e9 DF |
200 | }; |
201 | ||
6fd5c03f AZ |
202 | static int |
203 | max6900_probe(struct i2c_client *client, const struct i2c_device_id *id) | |
aa5bd7e9 | 204 | { |
6fd5c03f | 205 | struct rtc_device *rtc; |
aa5bd7e9 | 206 | |
6fd5c03f AZ |
207 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) |
208 | return -ENODEV; | |
aa5bd7e9 | 209 | |
feb141d1 JH |
210 | rtc = devm_rtc_device_register(&client->dev, max6900_driver.driver.name, |
211 | &max6900_rtc_ops, THIS_MODULE); | |
6fd5c03f AZ |
212 | if (IS_ERR(rtc)) |
213 | return PTR_ERR(rtc); | |
aa5bd7e9 DF |
214 | |
215 | i2c_set_clientdata(client, rtc); | |
216 | ||
217 | return 0; | |
aa5bd7e9 DF |
218 | } |
219 | ||
45a63518 | 220 | static const struct i2c_device_id max6900_id[] = { |
fe102c71 AZ |
221 | { "max6900", 0 }, |
222 | { } | |
223 | }; | |
8ad0f5b6 | 224 | MODULE_DEVICE_TABLE(i2c, max6900_id); |
fe102c71 | 225 | |
6fd5c03f AZ |
226 | static struct i2c_driver max6900_driver = { |
227 | .driver = { | |
228 | .name = "rtc-max6900", | |
229 | }, | |
230 | .probe = max6900_probe, | |
fe102c71 | 231 | .id_table = max6900_id, |
6fd5c03f AZ |
232 | }; |
233 | ||
0abc9201 | 234 | module_i2c_driver(max6900_driver); |
aa5bd7e9 DF |
235 | |
236 | MODULE_DESCRIPTION("Maxim MAX6900 RTC driver"); | |
6fd5c03f | 237 | MODULE_AUTHOR("Dale Farnsworth <dale@farnsworth.org>"); |
aa5bd7e9 | 238 | MODULE_LICENSE("GPL"); |