1/*
2 *  linux/drivers/i2c/chips/ds1337.c
3 *
4 *  Copyright (C) 2005 James Chapman <jchapman@katalix.com>
5 *
6 *	based on linux/drivers/acorn/char/pcf8583.c
7 *  Copyright (C) 2000 Russell King
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12 *
13 * Driver for Dallas Semiconductor DS1337 and DS1339 real time clock chip
14 */
15
16#include <linux/module.h>
17#include <linux/init.h>
18#include <linux/slab.h>
19#include <linux/i2c.h>
20#include <linux/string.h>
21#include <linux/rtc.h>		/* get the user-level API */
22#include <linux/bcd.h>
23#include <linux/list.h>
24
25/* Device registers */
26#define DS1337_REG_HOUR		2
27#define DS1337_REG_DAY		3
28#define DS1337_REG_DATE		4
29#define DS1337_REG_MONTH	5
30#define DS1337_REG_CONTROL	14
31#define DS1337_REG_STATUS	15
32
33#define DS1337_GET_DATE		0
34#define DS1337_SET_DATE		1
35
36/*
37 * Functions declaration
38 */
39static unsigned short normal_i2c[] = { 0x68, I2C_CLIENT_END };
40
41I2C_CLIENT_INSMOD_1(ds1337);
42
43static int ds1337_attach_adapter(struct i2c_adapter *adapter);
44static int ds1337_detect(struct i2c_adapter *adapter, int address, int kind);
45static void ds1337_init_client(struct i2c_client *client);
46static int ds1337_detach_client(struct i2c_client *client);
47static int ds1337_command(struct i2c_client *client, unsigned int cmd,
48			  void *arg);
49
50/*
51 * Driver data (common to all clients)
52 */
53static struct i2c_driver ds1337_driver = {
54	.driver = {
55		.name	= "ds1337",
56	},
57	.attach_adapter	= ds1337_attach_adapter,
58	.detach_client	= ds1337_detach_client,
59	.command	= ds1337_command,
60};
61
62/*
63 * Client data (each client gets its own)
64 */
65struct ds1337_data {
66	struct i2c_client client;
67	struct list_head list;
68};
69
70/*
71 * Internal variables
72 */
73static LIST_HEAD(ds1337_clients);
74
75static inline int ds1337_read(struct i2c_client *client, u8 reg, u8 *value)
76{
77	s32 tmp = i2c_smbus_read_byte_data(client, reg);
78
79	if (tmp < 0)
80		return -EIO;
81
82	*value = tmp;
83
84	return 0;
85}
86
87/*
88 * Chip access functions
89 */
90static int ds1337_get_datetime(struct i2c_client *client, struct rtc_time *dt)
91{
92	int result;
93	u8 buf[7];
94	u8 val;
95	struct i2c_msg msg[2];
96	u8 offs = 0;
97
98	if (!dt) {
99		dev_dbg(&client->dev, "%s: EINVAL: dt=NULL\n", __FUNCTION__);
100		return -EINVAL;
101	}
102
103	msg[0].addr = client->addr;
104	msg[0].flags = 0;
105	msg[0].len = 1;
106	msg[0].buf = &offs;
107
108	msg[1].addr = client->addr;
109	msg[1].flags = I2C_M_RD;
110	msg[1].len = sizeof(buf);
111	msg[1].buf = &buf[0];
112
113	result = i2c_transfer(client->adapter, msg, 2);
114
115	dev_dbg(&client->dev, "%s: [%d] %02x %02x %02x %02x %02x %02x %02x\n",
116		__FUNCTION__, result, buf[0], buf[1], buf[2], buf[3],
117		buf[4], buf[5], buf[6]);
118
119	if (result == 2) {
120		dt->tm_sec = BCD2BIN(buf[0]);
121		dt->tm_min = BCD2BIN(buf[1]);
122		val = buf[2] & 0x3f;
123		dt->tm_hour = BCD2BIN(val);
124		dt->tm_wday = BCD2BIN(buf[3]) - 1;
125		dt->tm_mday = BCD2BIN(buf[4]);
126		val = buf[5] & 0x7f;
127		dt->tm_mon = BCD2BIN(val) - 1;
128		dt->tm_year = BCD2BIN(buf[6]);
129		if (buf[5] & 0x80)
130			dt->tm_year += 100;
131
132		dev_dbg(&client->dev, "%s: secs=%d, mins=%d, "
133			"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
134			__FUNCTION__, dt->tm_sec, dt->tm_min,
135			dt->tm_hour, dt->tm_mday,
136			dt->tm_mon, dt->tm_year, dt->tm_wday);
137
138		return 0;
139	}
140
141	dev_err(&client->dev, "error reading data! %d\n", result);
142	return -EIO;
143}
144
145static int ds1337_set_datetime(struct i2c_client *client, struct rtc_time *dt)
146{
147	int result;
148	u8 buf[8];
149	u8 val;
150	struct i2c_msg msg[1];
151
152	if (!dt) {
153		dev_dbg(&client->dev, "%s: EINVAL: dt=NULL\n", __FUNCTION__);
154		return -EINVAL;
155	}
156
157	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
158		"mday=%d, mon=%d, year=%d, wday=%d\n", __FUNCTION__,
159		dt->tm_sec, dt->tm_min, dt->tm_hour,
160		dt->tm_mday, dt->tm_mon, dt->tm_year, dt->tm_wday);
161
162	buf[0] = 0;		/* reg offset */
163	buf[1] = BIN2BCD(dt->tm_sec);
164	buf[2] = BIN2BCD(dt->tm_min);
165	buf[3] = BIN2BCD(dt->tm_hour);
166	buf[4] = BIN2BCD(dt->tm_wday + 1);
167	buf[5] = BIN2BCD(dt->tm_mday);
168	buf[6] = BIN2BCD(dt->tm_mon + 1);
169	val = dt->tm_year;
170	if (val >= 100) {
171		val -= 100;
172		buf[6] |= (1 << 7);
173	}
174	buf[7] = BIN2BCD(val);
175
176	msg[0].addr = client->addr;
177	msg[0].flags = 0;
178	msg[0].len = sizeof(buf);
179	msg[0].buf = &buf[0];
180
181	result = i2c_transfer(client->adapter, msg, 1);
182	if (result == 1)
183		return 0;
184
185	dev_err(&client->dev, "error writing data! %d\n", result);
186	return -EIO;
187}
188
189static int ds1337_command(struct i2c_client *client, unsigned int cmd,
190			  void *arg)
191{
192	dev_dbg(&client->dev, "%s: cmd=%d\n", __FUNCTION__, cmd);
193
194	switch (cmd) {
195	case DS1337_GET_DATE:
196		return ds1337_get_datetime(client, arg);
197
198	case DS1337_SET_DATE:
199		return ds1337_set_datetime(client, arg);
200
201	default:
202		return -EINVAL;
203	}
204}
205
206/*
207 * Public API for access to specific device. Useful for low-level
208 * RTC access from kernel code.
209 */
210int ds1337_do_command(int bus, int cmd, void *arg)
211{
212	struct list_head *walk;
213	struct list_head *tmp;
214	struct ds1337_data *data;
215
216	list_for_each_safe(walk, tmp, &ds1337_clients) {
217		data = list_entry(walk, struct ds1337_data, list);
218		if (data->client.adapter->nr == bus)
219			return ds1337_command(&data->client, cmd, arg);
220	}
221
222	return -ENODEV;
223}
224
225static int ds1337_attach_adapter(struct i2c_adapter *adapter)
226{
227	return i2c_probe(adapter, &addr_data, ds1337_detect);
228}
229
230/*
231 * The following function does more than just detection. If detection
232 * succeeds, it also registers the new chip.
233 */
234static int ds1337_detect(struct i2c_adapter *adapter, int address, int kind)
235{
236	struct i2c_client *new_client;
237	struct ds1337_data *data;
238	int err = 0;
239	const char *name = "";
240
241	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
242				     I2C_FUNC_I2C))
243		goto exit;
244
245	if (!(data = kzalloc(sizeof(struct ds1337_data), GFP_KERNEL))) {
246		err = -ENOMEM;
247		goto exit;
248	}
249	INIT_LIST_HEAD(&data->list);
250
251	/* The common I2C client data is placed right before the
252	 * DS1337-specific data.
253	 */
254	new_client = &data->client;
255	i2c_set_clientdata(new_client, data);
256	new_client->addr = address;
257	new_client->adapter = adapter;
258	new_client->driver = &ds1337_driver;
259	new_client->flags = 0;
260
261	/*
262	 * Now we do the remaining detection. A negative kind means that
263	 * the driver was loaded with no force parameter (default), so we
264	 * must both detect and identify the chip. A zero kind means that
265	 * the driver was loaded with the force parameter, the detection
266	 * step shall be skipped. A positive kind means that the driver
267	 * was loaded with the force parameter and a given kind of chip is
268	 * requested, so both the detection and the identification steps
269	 * are skipped.
270	 *
271	 * For detection, we read registers that are most likely to cause
272	 * detection failure, i.e. those that have more bits with fixed
273	 * or reserved values.
274	 */
275
276	/* Default to an DS1337 if forced */
277	if (kind == 0)
278		kind = ds1337;
279
280	if (kind < 0) {		/* detection and identification */
281		u8 data;
282
283		/* Check that status register bits 6-2 are zero */
284		if ((ds1337_read(new_client, DS1337_REG_STATUS, &data) < 0) ||
285		    (data & 0x7c))
286			goto exit_free;
287
288		/* Check for a valid day register value */
289		if ((ds1337_read(new_client, DS1337_REG_DAY, &data) < 0) ||
290		    (data == 0) || (data & 0xf8))
291			goto exit_free;
292
293		/* Check for a valid date register value */
294		if ((ds1337_read(new_client, DS1337_REG_DATE, &data) < 0) ||
295		    (data == 0) || (data & 0xc0) || ((data & 0x0f) > 9) ||
296		    (data >= 0x32))
297			goto exit_free;
298
299		/* Check for a valid month register value */
300		if ((ds1337_read(new_client, DS1337_REG_MONTH, &data) < 0) ||
301		    (data == 0) || (data & 0x60) || ((data & 0x0f) > 9) ||
302		    ((data >= 0x13) && (data <= 0x19)))
303			goto exit_free;
304
305		/* Check that control register bits 6-5 are zero */
306		if ((ds1337_read(new_client, DS1337_REG_CONTROL, &data) < 0) ||
307		    (data & 0x60))
308			goto exit_free;
309
310		kind = ds1337;
311	}
312
313	if (kind == ds1337)
314		name = "ds1337";
315
316	/* We can fill in the remaining client fields */
317	strlcpy(new_client->name, name, I2C_NAME_SIZE);
318
319	/* Tell the I2C layer a new client has arrived */
320	if ((err = i2c_attach_client(new_client)))
321		goto exit_free;
322
323	/* Initialize the DS1337 chip */
324	ds1337_init_client(new_client);
325
326	/* Add client to local list */
327	list_add(&data->list, &ds1337_clients);
328
329	return 0;
330
331exit_free:
332	kfree(data);
333exit:
334	return err;
335}
336
337static void ds1337_init_client(struct i2c_client *client)
338{
339	u8 status, control;
340
341	/* On some boards, the RTC isn't configured by boot firmware.
342	 * Handle that case by starting/configuring the RTC now.
343	 */
344	status = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
345	control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
346
347	if ((status & 0x80) || (control & 0x80)) {
348		/* RTC not running */
349		u8 buf[1+16];	/* First byte is interpreted as address */
350		struct i2c_msg msg[1];
351
352		dev_dbg(&client->dev, "%s: RTC not running!\n", __FUNCTION__);
353
354		/* Initialize all, including STATUS and CONTROL to zero */
355		memset(buf, 0, sizeof(buf));
356
357		/* Write valid values in the date/time registers */
358		buf[1+DS1337_REG_DAY] = 1;
359		buf[1+DS1337_REG_DATE] = 1;
360		buf[1+DS1337_REG_MONTH] = 1;
361
362		msg[0].addr = client->addr;
363		msg[0].flags = 0;
364		msg[0].len = sizeof(buf);
365		msg[0].buf = &buf[0];
366
367		i2c_transfer(client->adapter, msg, 1);
368	} else {
369		/* Running: ensure that device is set in 24-hour mode */
370		s32 val;
371
372		val = i2c_smbus_read_byte_data(client, DS1337_REG_HOUR);
373		if ((val >= 0) && (val & (1 << 6)))
374			i2c_smbus_write_byte_data(client, DS1337_REG_HOUR,
375						  val & 0x3f);
376	}
377}
378
379static int ds1337_detach_client(struct i2c_client *client)
380{
381	int err;
382	struct ds1337_data *data = i2c_get_clientdata(client);
383
384	if ((err = i2c_detach_client(client)))
385		return err;
386
387	list_del(&data->list);
388	kfree(data);
389	return 0;
390}
391
392static int __init ds1337_init(void)
393{
394	return i2c_add_driver(&ds1337_driver);
395}
396
397static void __exit ds1337_exit(void)
398{
399	i2c_del_driver(&ds1337_driver);
400}
401
402MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
403MODULE_DESCRIPTION("DS1337 RTC driver");
404MODULE_LICENSE("GPL");
405
406EXPORT_SYMBOL_GPL(ds1337_do_command);
407
408module_init(ds1337_init);
409module_exit(ds1337_exit);
410