1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * An I2C driver for the Intersil ISL 12022
4 *
5 * Author: Roman Fietze <roman.fietze@telemotive.de>
6 *
7 * Based on the Philips PCF8563 RTC
8 * by Alessandro Zummo <a.zummo@towertech.it>.
9 */
10
11 #include <linux/i2c.h>
12 #include <linux/bcd.h>
13 #include <linux/rtc.h>
14 #include <linux/slab.h>
15 #include <linux/module.h>
16 #include <linux/err.h>
17 #include <linux/of.h>
18 #include <linux/of_device.h>
19
20 /* ISL register offsets */
21 #define ISL12022_REG_SC 0x00
22 #define ISL12022_REG_MN 0x01
23 #define ISL12022_REG_HR 0x02
24 #define ISL12022_REG_DT 0x03
25 #define ISL12022_REG_MO 0x04
26 #define ISL12022_REG_YR 0x05
27 #define ISL12022_REG_DW 0x06
28
29 #define ISL12022_REG_SR 0x07
30 #define ISL12022_REG_INT 0x08
31
32 /* ISL register bits */
33 #define ISL12022_HR_MIL (1 << 7) /* military or 24 hour time */
34
35 #define ISL12022_SR_LBAT85 (1 << 2)
36 #define ISL12022_SR_LBAT75 (1 << 1)
37
38 #define ISL12022_INT_WRTC (1 << 6)
39
40
41 static struct i2c_driver isl12022_driver;
42
43 struct isl12022 {
44 struct rtc_device *rtc;
45
46 bool write_enabled; /* true if write enable is set */
47 };
48
49
isl12022_read_regs(struct i2c_client * client,uint8_t reg,uint8_t * data,size_t n)50 static int isl12022_read_regs(struct i2c_client *client, uint8_t reg,
51 uint8_t *data, size_t n)
52 {
53 struct i2c_msg msgs[] = {
54 {
55 .addr = client->addr,
56 .flags = 0,
57 .len = 1,
58 .buf = data
59 }, /* setup read ptr */
60 {
61 .addr = client->addr,
62 .flags = I2C_M_RD,
63 .len = n,
64 .buf = data
65 }
66 };
67
68 int ret;
69
70 data[0] = reg;
71 ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
72 if (ret != ARRAY_SIZE(msgs)) {
73 dev_err(&client->dev, "%s: read error, ret=%d\n",
74 __func__, ret);
75 return -EIO;
76 }
77
78 return 0;
79 }
80
81
isl12022_write_reg(struct i2c_client * client,uint8_t reg,uint8_t val)82 static int isl12022_write_reg(struct i2c_client *client,
83 uint8_t reg, uint8_t val)
84 {
85 uint8_t data[2] = { reg, val };
86 int err;
87
88 err = i2c_master_send(client, data, sizeof(data));
89 if (err != sizeof(data)) {
90 dev_err(&client->dev,
91 "%s: err=%d addr=%02x, data=%02x\n",
92 __func__, err, data[0], data[1]);
93 return -EIO;
94 }
95
96 return 0;
97 }
98
99
100 /*
101 * In the routines that deal directly with the isl12022 hardware, we use
102 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
103 */
isl12022_rtc_read_time(struct device * dev,struct rtc_time * tm)104 static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
105 {
106 struct i2c_client *client = to_i2c_client(dev);
107 uint8_t buf[ISL12022_REG_INT + 1];
108 int ret;
109
110 ret = isl12022_read_regs(client, ISL12022_REG_SC, buf, sizeof(buf));
111 if (ret)
112 return ret;
113
114 if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) {
115 dev_warn(&client->dev,
116 "voltage dropped below %u%%, "
117 "date and time is not reliable.\n",
118 buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75);
119 }
120
121 dev_dbg(&client->dev,
122 "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
123 "mday=%02x, mon=%02x, year=%02x, wday=%02x, "
124 "sr=%02x, int=%02x",
125 __func__,
126 buf[ISL12022_REG_SC],
127 buf[ISL12022_REG_MN],
128 buf[ISL12022_REG_HR],
129 buf[ISL12022_REG_DT],
130 buf[ISL12022_REG_MO],
131 buf[ISL12022_REG_YR],
132 buf[ISL12022_REG_DW],
133 buf[ISL12022_REG_SR],
134 buf[ISL12022_REG_INT]);
135
136 tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
137 tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
138 tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
139 tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
140 tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
141 tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
142 tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;
143
144 dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
145 "mday=%d, mon=%d, year=%d, wday=%d\n",
146 __func__,
147 tm->tm_sec, tm->tm_min, tm->tm_hour,
148 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
149
150 return 0;
151 }
152
isl12022_rtc_set_time(struct device * dev,struct rtc_time * tm)153 static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
154 {
155 struct i2c_client *client = to_i2c_client(dev);
156 struct isl12022 *isl12022 = i2c_get_clientdata(client);
157 size_t i;
158 int ret;
159 uint8_t buf[ISL12022_REG_DW + 1];
160
161 dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
162 "mday=%d, mon=%d, year=%d, wday=%d\n",
163 __func__,
164 tm->tm_sec, tm->tm_min, tm->tm_hour,
165 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
166
167 if (!isl12022->write_enabled) {
168
169 ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1);
170 if (ret)
171 return ret;
172
173 /* Check if WRTC (write rtc enable) is set factory default is
174 * 0 (not set) */
175 if (!(buf[0] & ISL12022_INT_WRTC)) {
176 dev_info(&client->dev,
177 "init write enable and 24 hour format\n");
178
179 /* Set the write enable bit. */
180 ret = isl12022_write_reg(client,
181 ISL12022_REG_INT,
182 buf[0] | ISL12022_INT_WRTC);
183 if (ret)
184 return ret;
185
186 /* Write to any RTC register to start RTC, we use the
187 * HR register, setting the MIL bit to use the 24 hour
188 * format. */
189 ret = isl12022_read_regs(client, ISL12022_REG_HR,
190 buf, 1);
191 if (ret)
192 return ret;
193
194 ret = isl12022_write_reg(client,
195 ISL12022_REG_HR,
196 buf[0] | ISL12022_HR_MIL);
197 if (ret)
198 return ret;
199 }
200
201 isl12022->write_enabled = true;
202 }
203
204 /* hours, minutes and seconds */
205 buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
206 buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
207 buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL;
208
209 buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
210
211 /* month, 1 - 12 */
212 buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
213
214 /* year and century */
215 buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
216
217 buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
218
219 /* write register's data */
220 for (i = 0; i < ARRAY_SIZE(buf); i++) {
221 ret = isl12022_write_reg(client, ISL12022_REG_SC + i,
222 buf[ISL12022_REG_SC + i]);
223 if (ret)
224 return -EIO;
225 }
226
227 return 0;
228 }
229
230 static const struct rtc_class_ops isl12022_rtc_ops = {
231 .read_time = isl12022_rtc_read_time,
232 .set_time = isl12022_rtc_set_time,
233 };
234
isl12022_probe(struct i2c_client * client,const struct i2c_device_id * id)235 static int isl12022_probe(struct i2c_client *client,
236 const struct i2c_device_id *id)
237 {
238 struct isl12022 *isl12022;
239
240 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
241 return -ENODEV;
242
243 isl12022 = devm_kzalloc(&client->dev, sizeof(struct isl12022),
244 GFP_KERNEL);
245 if (!isl12022)
246 return -ENOMEM;
247
248 i2c_set_clientdata(client, isl12022);
249
250 isl12022->rtc = devm_rtc_device_register(&client->dev,
251 isl12022_driver.driver.name,
252 &isl12022_rtc_ops, THIS_MODULE);
253 return PTR_ERR_OR_ZERO(isl12022->rtc);
254 }
255
256 #ifdef CONFIG_OF
257 static const struct of_device_id isl12022_dt_match[] = {
258 { .compatible = "isl,isl12022" }, /* for backward compat., don't use */
259 { .compatible = "isil,isl12022" },
260 { },
261 };
262 MODULE_DEVICE_TABLE(of, isl12022_dt_match);
263 #endif
264
265 static const struct i2c_device_id isl12022_id[] = {
266 { "isl12022", 0 },
267 { }
268 };
269 MODULE_DEVICE_TABLE(i2c, isl12022_id);
270
271 static struct i2c_driver isl12022_driver = {
272 .driver = {
273 .name = "rtc-isl12022",
274 #ifdef CONFIG_OF
275 .of_match_table = of_match_ptr(isl12022_dt_match),
276 #endif
277 },
278 .probe = isl12022_probe,
279 .id_table = isl12022_id,
280 };
281
282 module_i2c_driver(isl12022_driver);
283
284 MODULE_AUTHOR("roman.fietze@telemotive.de");
285 MODULE_DESCRIPTION("ISL 12022 RTC driver");
286 MODULE_LICENSE("GPL");
287