1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * An rtc/i2c driver for the Dallas DS1672 |
4 | * Copyright 2005-06 Tower Technologies |
5 | * |
6 | * Author: Alessandro Zummo <a.zummo@towertech.it> |
7 | */ |
8 | |
9 | #include <linux/i2c.h> |
10 | #include <linux/rtc.h> |
11 | #include <linux/module.h> |
12 | |
13 | /* Registers */ |
14 | |
15 | #define DS1672_REG_CNT_BASE 0 |
16 | #define DS1672_REG_CONTROL 4 |
17 | #define DS1672_REG_TRICKLE 5 |
18 | |
19 | #define DS1672_REG_CONTROL_EOSC 0x80 |
20 | |
21 | /* |
22 | * In the routines that deal directly with the ds1672 hardware, we use |
23 | * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch |
24 | * Time is set to UTC. |
25 | */ |
26 | static int ds1672_read_time(struct device *dev, struct rtc_time *tm) |
27 | { |
28 | struct i2c_client *client = to_i2c_client(dev); |
29 | unsigned long time; |
30 | unsigned char addr = DS1672_REG_CONTROL; |
31 | unsigned char buf[4]; |
32 | |
33 | struct i2c_msg msgs[] = { |
34 | {/* setup read ptr */ |
35 | .addr = client->addr, |
36 | .len = 1, |
37 | .buf = &addr |
38 | }, |
39 | {/* read date */ |
40 | .addr = client->addr, |
41 | .flags = I2C_M_RD, |
42 | .len = 1, |
43 | .buf = buf |
44 | }, |
45 | }; |
46 | |
47 | /* read control register */ |
48 | if ((i2c_transfer(adap: client->adapter, msgs: &msgs[0], num: 2)) != 2) { |
49 | dev_warn(&client->dev, "Unable to read the control register\n" ); |
50 | return -EIO; |
51 | } |
52 | |
53 | if (buf[0] & DS1672_REG_CONTROL_EOSC) { |
54 | dev_warn(&client->dev, "Oscillator not enabled. Set time to enable.\n" ); |
55 | return -EINVAL; |
56 | } |
57 | |
58 | addr = DS1672_REG_CNT_BASE; |
59 | msgs[1].len = 4; |
60 | |
61 | /* read date registers */ |
62 | if ((i2c_transfer(adap: client->adapter, msgs: &msgs[0], num: 2)) != 2) { |
63 | dev_err(&client->dev, "%s: read error\n" , __func__); |
64 | return -EIO; |
65 | } |
66 | |
67 | dev_dbg(&client->dev, |
68 | "%s: raw read data - counters=%02x,%02x,%02x,%02x\n" , |
69 | __func__, buf[0], buf[1], buf[2], buf[3]); |
70 | |
71 | time = ((unsigned long)buf[3] << 24) | (buf[2] << 16) | |
72 | (buf[1] << 8) | buf[0]; |
73 | |
74 | rtc_time64_to_tm(time, tm); |
75 | |
76 | dev_dbg(&client->dev, "%s: tm is %ptR\n" , __func__, tm); |
77 | |
78 | return 0; |
79 | } |
80 | |
81 | static int ds1672_set_time(struct device *dev, struct rtc_time *tm) |
82 | { |
83 | struct i2c_client *client = to_i2c_client(dev); |
84 | int xfer; |
85 | unsigned char buf[6]; |
86 | unsigned long secs = rtc_tm_to_time64(tm); |
87 | |
88 | buf[0] = DS1672_REG_CNT_BASE; |
89 | buf[1] = secs & 0x000000FF; |
90 | buf[2] = (secs & 0x0000FF00) >> 8; |
91 | buf[3] = (secs & 0x00FF0000) >> 16; |
92 | buf[4] = (secs & 0xFF000000) >> 24; |
93 | buf[5] = 0; /* set control reg to enable counting */ |
94 | |
95 | xfer = i2c_master_send(client, buf, count: 6); |
96 | if (xfer != 6) { |
97 | dev_err(&client->dev, "%s: send: %d\n" , __func__, xfer); |
98 | return -EIO; |
99 | } |
100 | |
101 | return 0; |
102 | } |
103 | |
104 | static const struct rtc_class_ops ds1672_rtc_ops = { |
105 | .read_time = ds1672_read_time, |
106 | .set_time = ds1672_set_time, |
107 | }; |
108 | |
109 | static int ds1672_probe(struct i2c_client *client) |
110 | { |
111 | int err = 0; |
112 | struct rtc_device *rtc; |
113 | |
114 | dev_dbg(&client->dev, "%s\n" , __func__); |
115 | |
116 | if (!i2c_check_functionality(adap: client->adapter, I2C_FUNC_I2C)) |
117 | return -ENODEV; |
118 | |
119 | rtc = devm_rtc_allocate_device(dev: &client->dev); |
120 | if (IS_ERR(ptr: rtc)) |
121 | return PTR_ERR(ptr: rtc); |
122 | |
123 | rtc->ops = &ds1672_rtc_ops; |
124 | rtc->range_max = U32_MAX; |
125 | |
126 | err = devm_rtc_register_device(rtc); |
127 | if (err) |
128 | return err; |
129 | |
130 | i2c_set_clientdata(client, data: rtc); |
131 | |
132 | return 0; |
133 | } |
134 | |
135 | static const struct i2c_device_id ds1672_id[] = { |
136 | { "ds1672" , 0 }, |
137 | { } |
138 | }; |
139 | MODULE_DEVICE_TABLE(i2c, ds1672_id); |
140 | |
141 | static const __maybe_unused struct of_device_id ds1672_of_match[] = { |
142 | { .compatible = "dallas,ds1672" }, |
143 | { } |
144 | }; |
145 | MODULE_DEVICE_TABLE(of, ds1672_of_match); |
146 | |
147 | static struct i2c_driver ds1672_driver = { |
148 | .driver = { |
149 | .name = "rtc-ds1672" , |
150 | .of_match_table = of_match_ptr(ds1672_of_match), |
151 | }, |
152 | .probe = ds1672_probe, |
153 | .id_table = ds1672_id, |
154 | }; |
155 | |
156 | module_i2c_driver(ds1672_driver); |
157 | |
158 | MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>" ); |
159 | MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver" ); |
160 | MODULE_LICENSE("GPL" ); |
161 | |