1/*
2 * A driver for the I2C members of the Abracon AB x8xx RTC family,
3 * and compatible: AB 1805 and AB 0805
4 *
5 * Copyright 2014-2015 Macq S.A.
6 *
7 * Author: Philippe De Muyter <phdm@macqel.be>
8 * Author: Alexandre Belloni <alexandre.belloni@free-electrons.com>
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 *
14 */
15
16#include <linux/bcd.h>
17#include <linux/i2c.h>
18#include <linux/module.h>
19#include <linux/rtc.h>
20
21#define ABX8XX_REG_HTH		0x00
22#define ABX8XX_REG_SC		0x01
23#define ABX8XX_REG_MN		0x02
24#define ABX8XX_REG_HR		0x03
25#define ABX8XX_REG_DA		0x04
26#define ABX8XX_REG_MO		0x05
27#define ABX8XX_REG_YR		0x06
28#define ABX8XX_REG_WD		0x07
29
30#define ABX8XX_REG_CTRL1	0x10
31#define ABX8XX_CTRL_WRITE	BIT(0)
32#define ABX8XX_CTRL_12_24	BIT(6)
33
34#define ABX8XX_REG_CFG_KEY	0x1f
35#define ABX8XX_CFG_KEY_MISC	0x9d
36
37#define ABX8XX_REG_ID0		0x28
38
39#define ABX8XX_REG_TRICKLE	0x20
40#define ABX8XX_TRICKLE_CHARGE_ENABLE	0xa0
41#define ABX8XX_TRICKLE_STANDARD_DIODE	0x8
42#define ABX8XX_TRICKLE_SCHOTTKY_DIODE	0x4
43
44static u8 trickle_resistors[] = {0, 3, 6, 11};
45
46enum abx80x_chip {AB0801, AB0803, AB0804, AB0805,
47	AB1801, AB1803, AB1804, AB1805, ABX80X};
48
49struct abx80x_cap {
50	u16 pn;
51	bool has_tc;
52};
53
54static struct abx80x_cap abx80x_caps[] = {
55	[AB0801] = {.pn = 0x0801},
56	[AB0803] = {.pn = 0x0803},
57	[AB0804] = {.pn = 0x0804, .has_tc = true},
58	[AB0805] = {.pn = 0x0805, .has_tc = true},
59	[AB1801] = {.pn = 0x1801},
60	[AB1803] = {.pn = 0x1803},
61	[AB1804] = {.pn = 0x1804, .has_tc = true},
62	[AB1805] = {.pn = 0x1805, .has_tc = true},
63	[ABX80X] = {.pn = 0}
64};
65
66static struct i2c_driver abx80x_driver;
67
68static int abx80x_enable_trickle_charger(struct i2c_client *client,
69					 u8 trickle_cfg)
70{
71	int err;
72
73	/*
74	 * Write the configuration key register to enable access to the Trickle
75	 * register
76	 */
77	err = i2c_smbus_write_byte_data(client, ABX8XX_REG_CFG_KEY,
78					ABX8XX_CFG_KEY_MISC);
79	if (err < 0) {
80		dev_err(&client->dev, "Unable to write configuration key\n");
81		return -EIO;
82	}
83
84	err = i2c_smbus_write_byte_data(client, ABX8XX_REG_TRICKLE,
85					ABX8XX_TRICKLE_CHARGE_ENABLE |
86					trickle_cfg);
87	if (err < 0) {
88		dev_err(&client->dev, "Unable to write trickle register\n");
89		return -EIO;
90	}
91
92	return 0;
93}
94
95static int abx80x_rtc_read_time(struct device *dev, struct rtc_time *tm)
96{
97	struct i2c_client *client = to_i2c_client(dev);
98	unsigned char buf[8];
99	int err;
100
101	err = i2c_smbus_read_i2c_block_data(client, ABX8XX_REG_HTH,
102					    sizeof(buf), buf);
103	if (err < 0) {
104		dev_err(&client->dev, "Unable to read date\n");
105		return -EIO;
106	}
107
108	tm->tm_sec = bcd2bin(buf[ABX8XX_REG_SC] & 0x7F);
109	tm->tm_min = bcd2bin(buf[ABX8XX_REG_MN] & 0x7F);
110	tm->tm_hour = bcd2bin(buf[ABX8XX_REG_HR] & 0x3F);
111	tm->tm_wday = buf[ABX8XX_REG_WD] & 0x7;
112	tm->tm_mday = bcd2bin(buf[ABX8XX_REG_DA] & 0x3F);
113	tm->tm_mon = bcd2bin(buf[ABX8XX_REG_MO] & 0x1F) - 1;
114	tm->tm_year = bcd2bin(buf[ABX8XX_REG_YR]) + 100;
115
116	err = rtc_valid_tm(tm);
117	if (err < 0)
118		dev_err(&client->dev, "retrieved date/time is not valid.\n");
119
120	return err;
121}
122
123static int abx80x_rtc_set_time(struct device *dev, struct rtc_time *tm)
124{
125	struct i2c_client *client = to_i2c_client(dev);
126	unsigned char buf[8];
127	int err;
128
129	if (tm->tm_year < 100)
130		return -EINVAL;
131
132	buf[ABX8XX_REG_HTH] = 0;
133	buf[ABX8XX_REG_SC] = bin2bcd(tm->tm_sec);
134	buf[ABX8XX_REG_MN] = bin2bcd(tm->tm_min);
135	buf[ABX8XX_REG_HR] = bin2bcd(tm->tm_hour);
136	buf[ABX8XX_REG_DA] = bin2bcd(tm->tm_mday);
137	buf[ABX8XX_REG_MO] = bin2bcd(tm->tm_mon + 1);
138	buf[ABX8XX_REG_YR] = bin2bcd(tm->tm_year - 100);
139	buf[ABX8XX_REG_WD] = tm->tm_wday;
140
141	err = i2c_smbus_write_i2c_block_data(client, ABX8XX_REG_HTH,
142					     sizeof(buf), buf);
143	if (err < 0) {
144		dev_err(&client->dev, "Unable to write to date registers\n");
145		return -EIO;
146	}
147
148	return 0;
149}
150
151static const struct rtc_class_ops abx80x_rtc_ops = {
152	.read_time	= abx80x_rtc_read_time,
153	.set_time	= abx80x_rtc_set_time,
154};
155
156static int abx80x_dt_trickle_cfg(struct device_node *np)
157{
158	const char *diode;
159	int trickle_cfg = 0;
160	int i, ret;
161	u32 tmp;
162
163	ret = of_property_read_string(np, "abracon,tc-diode", &diode);
164	if (ret)
165		return ret;
166
167	if (!strcmp(diode, "standard"))
168		trickle_cfg |= ABX8XX_TRICKLE_STANDARD_DIODE;
169	else if (!strcmp(diode, "schottky"))
170		trickle_cfg |= ABX8XX_TRICKLE_SCHOTTKY_DIODE;
171	else
172		return -EINVAL;
173
174	ret = of_property_read_u32(np, "abracon,tc-resistor", &tmp);
175	if (ret)
176		return ret;
177
178	for (i = 0; i < sizeof(trickle_resistors); i++)
179		if (trickle_resistors[i] == tmp)
180			break;
181
182	if (i == sizeof(trickle_resistors))
183		return -EINVAL;
184
185	return (trickle_cfg | i);
186}
187
188static int abx80x_probe(struct i2c_client *client,
189			const struct i2c_device_id *id)
190{
191	struct device_node *np = client->dev.of_node;
192	struct rtc_device *rtc;
193	int i, data, err, trickle_cfg = -EINVAL;
194	char buf[7];
195	unsigned int part = id->driver_data;
196	unsigned int partnumber;
197	unsigned int majrev, minrev;
198	unsigned int lot;
199	unsigned int wafer;
200	unsigned int uid;
201
202	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
203		return -ENODEV;
204
205	err = i2c_smbus_read_i2c_block_data(client, ABX8XX_REG_ID0,
206					    sizeof(buf), buf);
207	if (err < 0) {
208		dev_err(&client->dev, "Unable to read partnumber\n");
209		return -EIO;
210	}
211
212	partnumber = (buf[0] << 8) | buf[1];
213	majrev = buf[2] >> 3;
214	minrev = buf[2] & 0x7;
215	lot = ((buf[4] & 0x80) << 2) | ((buf[6] & 0x80) << 1) | buf[3];
216	uid = ((buf[4] & 0x7f) << 8) | buf[5];
217	wafer = (buf[6] & 0x7c) >> 2;
218	dev_info(&client->dev, "model %04x, revision %u.%u, lot %x, wafer %x, uid %x\n",
219		 partnumber, majrev, minrev, lot, wafer, uid);
220
221	data = i2c_smbus_read_byte_data(client, ABX8XX_REG_CTRL1);
222	if (data < 0) {
223		dev_err(&client->dev, "Unable to read control register\n");
224		return -EIO;
225	}
226
227	err = i2c_smbus_write_byte_data(client, ABX8XX_REG_CTRL1,
228					((data & ~ABX8XX_CTRL_12_24) |
229					 ABX8XX_CTRL_WRITE));
230	if (err < 0) {
231		dev_err(&client->dev, "Unable to write control register\n");
232		return -EIO;
233	}
234
235	/* part autodetection */
236	if (part == ABX80X) {
237		for (i = 0; abx80x_caps[i].pn; i++)
238			if (partnumber == abx80x_caps[i].pn)
239				break;
240		if (abx80x_caps[i].pn == 0) {
241			dev_err(&client->dev, "Unknown part: %04x\n",
242				partnumber);
243			return -EINVAL;
244		}
245		part = i;
246	}
247
248	if (partnumber != abx80x_caps[part].pn) {
249		dev_err(&client->dev, "partnumber mismatch %04x != %04x\n",
250			partnumber, abx80x_caps[part].pn);
251		return -EINVAL;
252	}
253
254	if (np && abx80x_caps[part].has_tc)
255		trickle_cfg = abx80x_dt_trickle_cfg(np);
256
257	if (trickle_cfg > 0) {
258		dev_info(&client->dev, "Enabling trickle charger: %02x\n",
259			 trickle_cfg);
260		abx80x_enable_trickle_charger(client, trickle_cfg);
261	}
262
263	rtc = devm_rtc_device_register(&client->dev, abx80x_driver.driver.name,
264				       &abx80x_rtc_ops, THIS_MODULE);
265
266	if (IS_ERR(rtc))
267		return PTR_ERR(rtc);
268
269	i2c_set_clientdata(client, rtc);
270
271	return 0;
272}
273
274static int abx80x_remove(struct i2c_client *client)
275{
276	return 0;
277}
278
279static const struct i2c_device_id abx80x_id[] = {
280	{ "abx80x", ABX80X },
281	{ "ab0801", AB0801 },
282	{ "ab0803", AB0803 },
283	{ "ab0804", AB0804 },
284	{ "ab0805", AB0805 },
285	{ "ab1801", AB1801 },
286	{ "ab1803", AB1803 },
287	{ "ab1804", AB1804 },
288	{ "ab1805", AB1805 },
289	{ }
290};
291MODULE_DEVICE_TABLE(i2c, abx80x_id);
292
293static struct i2c_driver abx80x_driver = {
294	.driver		= {
295		.name	= "rtc-abx80x",
296	},
297	.probe		= abx80x_probe,
298	.remove		= abx80x_remove,
299	.id_table	= abx80x_id,
300};
301
302module_i2c_driver(abx80x_driver);
303
304MODULE_AUTHOR("Philippe De Muyter <phdm@macqel.be>");
305MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>");
306MODULE_DESCRIPTION("Abracon ABX80X RTC driver");
307MODULE_LICENSE("GPL v2");
308