summaryrefslogtreecommitdiffstats
path: root/drivers/rtc/rtc-sd3078.c
blob: 42cb90db7f94eff831505df9e06299679bbe8a96 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
// SPDX-License-Identifier: GPL-2.0
/*
 * Real Time Clock (RTC) Driver for sd3078
 * Copyright (C) 2018 Zoro Li
 */

#include <linux/bcd.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/rtc.h>
#include <linux/slab.h>

#define SD3078_REG_SC			0x00
#define SD3078_REG_MN			0x01
#define SD3078_REG_HR			0x02
#define SD3078_REG_DW			0x03
#define SD3078_REG_DM			0x04
#define SD3078_REG_MO			0x05
#define SD3078_REG_YR			0x06

#define SD3078_REG_CTRL1		0x0f
#define SD3078_REG_CTRL2		0x10
#define SD3078_REG_CTRL3		0x11

#define KEY_WRITE1		0x80
#define KEY_WRITE2		0x04
#define KEY_WRITE3		0x80

#define NUM_TIME_REGS   (SD3078_REG_YR - SD3078_REG_SC + 1)

/*
 * The sd3078 has write protection
 * and we can choose whether or not to use it.
 * Write protection is turned off by default.
 */
#define WRITE_PROTECT_EN	0

struct sd3078 {
	struct rtc_device	*rtc;
	struct regmap		*regmap;
};

/*
 * In order to prevent arbitrary modification of the time register,
 * when modification of the register,
 * the "write" bit needs to be written in a certain order.
 * 1. set WRITE1 bit
 * 2. set WRITE2 bit
 * 3. set WRITE3 bit
 */
static void sd3078_enable_reg_write(struct sd3078 *sd3078)
{
	regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL2,
			   KEY_WRITE1, KEY_WRITE1);
	regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1,
			   KEY_WRITE2, KEY_WRITE2);
	regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1,
			   KEY_WRITE3, KEY_WRITE3);
}

#if WRITE_PROTECT_EN
/*
 * In order to prevent arbitrary modification of the time register,
 * we should disable the write function.
 * when disable write,
 * the "write" bit needs to be clear in a certain order.
 * 1. clear WRITE2 bit
 * 2. clear WRITE3 bit
 * 3. clear WRITE1 bit
 */
static void sd3078_disable_reg_write(struct sd3078 *sd3078)
{
	regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1,
			   KEY_WRITE2, 0);
	regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1,
			   KEY_WRITE3, 0);
	regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL2,
			   KEY_WRITE1, 0);
}
#endif

static int sd3078_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	unsigned char hour;
	unsigned char rtc_data[NUM_TIME_REGS] = {0};
	struct i2c_client *client = to_i2c_client(dev);
	struct sd3078 *sd3078 = i2c_get_clientdata(client);
	int ret;

	ret = regmap_bulk_read(sd3078->regmap, SD3078_REG_SC, rtc_data,
			       NUM_TIME_REGS);
	if (ret < 0) {
		dev_err(dev, "reading from RTC failed with err:%d\n", ret);
		return ret;
	}

	tm->tm_sec	= bcd2bin(rtc_data[SD3078_REG_SC] & 0x7F);
	tm->tm_min	= bcd2bin(rtc_data[SD3078_REG_MN] & 0x7F);

	/*
	 * The sd3078 supports 12/24 hour mode.
	 * When getting time,
	 * we need to convert the 12 hour mode to the 24 hour mode.
	 */
	hour = rtc_data[SD3078_REG_HR];
	if (hour & 0x80) /* 24H MODE */
		tm->tm_hour = bcd2bin(rtc_data[SD3078_REG_HR] & 0x3F);
	else if (hour & 0x20) /* 12H MODE PM */
		tm->tm_hour = bcd2bin(rtc_data[SD3078_REG_HR] & 0x1F) + 12;
	else /* 12H MODE AM */
		tm->tm_hour = bcd2bin(rtc_data[SD3078_REG_HR] & 0x1F);

	tm->tm_mday = bcd2bin(rtc_data[SD3078_REG_DM] & 0x3F);
	tm->tm_wday = rtc_data[SD3078_REG_DW] & 0x07;
	tm->tm_mon	= bcd2bin(rtc_data[SD3078_REG_MO] & 0x1F) - 1;
	tm->tm_year = bcd2bin(rtc_data[SD3078_REG_YR]) + 100;

	return 0;
}

static int sd3078_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	unsigned char rtc_data[NUM_TIME_REGS];
	struct i2c_client *client = to_i2c_client(dev);
	struct sd3078 *sd3078 = i2c_get_clientdata(client);
	int ret;

	rtc_data[SD3078_REG_SC] = bin2bcd(tm->tm_sec);
	rtc_data[SD3078_REG_MN] = bin2bcd(tm->tm_min);
	rtc_data[SD3078_REG_HR] = bin2bcd(tm->tm_hour) | 0x80;
	rtc_data[SD3078_REG_DM] = bin2bcd(tm->tm_mday);
	rtc_data[SD3078_REG_DW] = tm->tm_wday & 0x07;
	rtc_data[SD3078_REG_MO] = bin2bcd(tm->tm_mon) + 1;
	rtc_data[SD3078_REG_YR] = bin2bcd(tm->tm_year - 100);

#if WRITE_PROTECT_EN
	sd3078_enable_reg_write(sd3078);
#endif

	ret = regmap_bulk_write(sd3078->regmap, SD3078_REG_SC, rtc_data,
				NUM_TIME_REGS);
	if (ret < 0) {
		dev_err(dev, "writing to RTC failed with err:%d\n", ret);
		return ret;
	}

#if WRITE_PROTECT_EN
	sd3078_disable_reg_write(sd3078);
#endif

	return 0;
}

static const struct rtc_class_ops sd3078_rtc_ops = {
	.read_time	= sd3078_rtc_read_time,
	.set_time	= sd3078_rtc_set_time,
};

static const struct regmap_config regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.max_register = 0x11,
};

static int sd3078_probe(struct i2c_client *client,
			const struct i2c_device_id *id)
{
	int ret;
	struct sd3078 *sd3078;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
		return -ENODEV;

	sd3078 = devm_kzalloc(&client->dev, sizeof(*sd3078), GFP_KERNEL);
	if (!sd3078)
		return -ENOMEM;

	sd3078->regmap = devm_regmap_init_i2c(client, &regmap_config);
	if (IS_ERR(sd3078->regmap)) {
		dev_err(&client->dev, "regmap allocation failed\n");
		return PTR_ERR(sd3078->regmap);
	}

	i2c_set_clientdata(client, sd3078);

	sd3078->rtc = devm_rtc_allocate_device(&client->dev);
	if (IS_ERR(sd3078->rtc))
		return PTR_ERR(sd3078->rtc);

	sd3078->rtc->ops = &sd3078_rtc_ops;
	sd3078->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
	sd3078->rtc->range_max = RTC_TIMESTAMP_END_2099;

	ret = rtc_register_device(sd3078->rtc);
	if (ret) {
		dev_err(&client->dev, "failed to register rtc device\n");
		return ret;
	}

	sd3078_enable_reg_write(sd3078);

	return 0;
}

static const struct i2c_device_id sd3078_id[] = {
	{"sd3078", 0},
	{ }
};
MODULE_DEVICE_TABLE(i2c, sd3078_id);

static const struct of_device_id rtc_dt_match[] = {
	{ .compatible = "whwave,sd3078" },
	{},
};
MODULE_DEVICE_TABLE(of, rtc_dt_match);

static struct i2c_driver sd3078_driver = {
	.driver     = {
		.name   = "sd3078",
		.of_match_table = of_match_ptr(rtc_dt_match),
	},
	.probe      = sd3078_probe,
	.id_table   = sd3078_id,
};

module_i2c_driver(sd3078_driver);

MODULE_AUTHOR("Dianlong Li <long17.cool@163.com>");
MODULE_DESCRIPTION("SD3078 RTC driver");
MODULE_LICENSE("GPL v2");