1/*
2 *  drivers/rtc/rtc-pcf8583.c
3 *
4 *  Copyright (C) 2000 Russell King
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 *  Driver for PCF8583 RTC & RAM chip
11 *
12 *  Converted to the generic RTC susbsystem by G. Liakhovetski (2006)
13 */
14#include <linux/module.h>
15#include <linux/i2c.h>
16#include <linux/slab.h>
17#include <linux/string.h>
18#include <linux/mc146818rtc.h>
19#include <linux/init.h>
20#include <linux/errno.h>
21#include <linux/bcd.h>
22
23struct rtc_mem {
24	unsigned int	loc;
25	unsigned int	nr;
26	unsigned char	*data;
27};
28
29struct pcf8583 {
30	struct i2c_client client;
31	struct rtc_device *rtc;
32	unsigned char ctrl;
33};
34
35#define CTRL_STOP	0x80
36#define CTRL_HOLD	0x40
37#define CTRL_32KHZ	0x00
38#define CTRL_MASK	0x08
39#define CTRL_ALARMEN	0x04
40#define CTRL_ALARM	0x02
41#define CTRL_TIMER	0x01
42
43static unsigned short normal_i2c[] = { 0x50, I2C_CLIENT_END };
44
45/* Module parameters */
46I2C_CLIENT_INSMOD;
47
48static struct i2c_driver pcf8583_driver;
49
50#define get_ctrl(x)    ((struct pcf8583 *)i2c_get_clientdata(x))->ctrl
51#define set_ctrl(x, v) get_ctrl(x) = v
52
53#define CMOS_YEAR	(64 + 128)
54#define CMOS_CHECKSUM	(63)
55
56static int pcf8583_get_datetime(struct i2c_client *client, struct rtc_time *dt)
57{
58	unsigned char buf[8], addr[1] = { 1 };
59	struct i2c_msg msgs[2] = {
60		{
61			.addr = client->addr,
62			.flags = 0,
63			.len = 1,
64			.buf = addr,
65		}, {
66			.addr = client->addr,
67			.flags = I2C_M_RD,
68			.len = 6,
69			.buf = buf,
70		}
71	};
72	int ret;
73
74	memset(buf, 0, sizeof(buf));
75
76	ret = i2c_transfer(client->adapter, msgs, 2);
77	if (ret == 2) {
78		dt->tm_year = buf[4] >> 6;
79		dt->tm_wday = buf[5] >> 5;
80
81		buf[4] &= 0x3f;
82		buf[5] &= 0x1f;
83
84		dt->tm_sec = BCD2BIN(buf[1]);
85		dt->tm_min = BCD2BIN(buf[2]);
86		dt->tm_hour = BCD2BIN(buf[3]);
87		dt->tm_mday = BCD2BIN(buf[4]);
88		dt->tm_mon = BCD2BIN(buf[5]) - 1;
89	}
90
91	return ret == 2 ? 0 : -EIO;
92}
93
94static int pcf8583_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo)
95{
96	unsigned char buf[8];
97	int ret, len = 6;
98
99	buf[0] = 0;
100	buf[1] = get_ctrl(client) | 0x80;
101	buf[2] = 0;
102	buf[3] = BIN2BCD(dt->tm_sec);
103	buf[4] = BIN2BCD(dt->tm_min);
104	buf[5] = BIN2BCD(dt->tm_hour);
105
106	if (datetoo) {
107		len = 8;
108		buf[6] = BIN2BCD(dt->tm_mday) | (dt->tm_year << 6);
109		buf[7] = BIN2BCD(dt->tm_mon + 1)  | (dt->tm_wday << 5);
110	}
111
112	ret = i2c_master_send(client, (char *)buf, len);
113	if (ret != len)
114		return -EIO;
115
116	buf[1] = get_ctrl(client);
117	ret = i2c_master_send(client, (char *)buf, 2);
118
119	return ret == 2 ? 0 : -EIO;
120}
121
122static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl)
123{
124	*ctrl = get_ctrl(client);
125	return 0;
126}
127
128static int pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl)
129{
130	unsigned char buf[2];
131
132	buf[0] = 0;
133	buf[1] = *ctrl;
134	set_ctrl(client, *ctrl);
135
136	return i2c_master_send(client, (char *)buf, 2);
137}
138
139static int pcf8583_read_mem(struct i2c_client *client, struct rtc_mem *mem)
140{
141	unsigned char addr[1];
142	struct i2c_msg msgs[2] = {
143		{
144			.addr = client->addr,
145			.flags = 0,
146			.len = 1,
147			.buf = addr,
148		}, {
149			.addr = client->addr,
150			.flags = I2C_M_RD,
151			.len = mem->nr,
152			.buf = mem->data,
153		}
154	};
155
156	if (mem->loc < 8)
157		return -EINVAL;
158
159	addr[0] = mem->loc;
160
161	return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO;
162}
163
164static int pcf8583_write_mem(struct i2c_client *client, struct rtc_mem *mem)
165{
166	unsigned char addr[1];
167	struct i2c_msg msgs[2] = {
168		{
169			.addr = client->addr,
170			.flags = 0,
171			.len = 1,
172			.buf = addr,
173		}, {
174			.addr = client->addr,
175			.flags = I2C_M_NOSTART,
176			.len = mem->nr,
177			.buf = mem->data,
178		}
179	};
180
181	if (mem->loc < 8)
182		return -EINVAL;
183
184	addr[0] = mem->loc;
185
186	return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO;
187}
188
189static int pcf8583_rtc_read_time(struct device *dev, struct rtc_time *tm)
190{
191	struct i2c_client *client = to_i2c_client(dev);
192	unsigned char ctrl, year[2];
193	struct rtc_mem mem = { CMOS_YEAR, sizeof(year), year };
194	int real_year, year_offset, err;
195
196	/*
197	 * Ensure that the RTC is running.
198	 */
199	pcf8583_get_ctrl(client, &ctrl);
200	if (ctrl & (CTRL_STOP | CTRL_HOLD)) {
201		unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD);
202
203		printk(KERN_WARNING "RTC: resetting control %02x -> %02x\n",
204		       ctrl, new_ctrl);
205
206		if ((err = pcf8583_set_ctrl(client, &new_ctrl)) < 0)
207			return err;
208	}
209
210	if (pcf8583_get_datetime(client, tm) ||
211	    pcf8583_read_mem(client, &mem))
212		return -EIO;
213
214	real_year = year[0];
215
216	/*
217	 * The RTC year holds the LSB two bits of the current
218	 * year, which should reflect the LSB two bits of the
219	 * CMOS copy of the year.  Any difference indicates
220	 * that we have to correct the CMOS version.
221	 */
222	year_offset = tm->tm_year - (real_year & 3);
223	if (year_offset < 0)
224		/*
225		 * RTC year wrapped.  Adjust it appropriately.
226		 */
227		year_offset += 4;
228
229	tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900;
230
231	return 0;
232}
233
234static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm)
235{
236	struct i2c_client *client = to_i2c_client(dev);
237	unsigned char year[2], chk;
238	struct rtc_mem cmos_year  = { CMOS_YEAR, sizeof(year), year };
239	struct rtc_mem cmos_check = { CMOS_CHECKSUM, 1, &chk };
240	unsigned int proper_year = tm->tm_year + 1900;
241	int ret;
242
243	/*
244	 * The RTC's own 2-bit year must reflect the least
245	 * significant two bits of the CMOS year.
246	 */
247
248	ret = pcf8583_set_datetime(client, tm, 1);
249	if (ret)
250		return ret;
251
252	ret = pcf8583_read_mem(client, &cmos_check);
253	if (ret)
254		return ret;
255
256	ret = pcf8583_read_mem(client, &cmos_year);
257	if (ret)
258		return ret;
259
260	chk -= year[1] + year[0];
261
262	year[1] = proper_year / 100;
263	year[0] = proper_year % 100;
264
265	chk += year[1] + year[0];
266
267	ret = pcf8583_write_mem(client, &cmos_year);
268
269	if (ret)
270		return ret;
271
272	ret = pcf8583_write_mem(client, &cmos_check);
273
274	return ret;
275}
276
277static const struct rtc_class_ops pcf8583_rtc_ops = {
278	.read_time	= pcf8583_rtc_read_time,
279	.set_time	= pcf8583_rtc_set_time,
280};
281
282static int pcf8583_probe(struct i2c_adapter *adap, int addr, int kind);
283
284static int pcf8583_attach(struct i2c_adapter *adap)
285{
286	return i2c_probe(adap, &addr_data, pcf8583_probe);
287}
288
289static int pcf8583_detach(struct i2c_client *client)
290{
291	int err;
292	struct pcf8583 *pcf = i2c_get_clientdata(client);
293	struct rtc_device *rtc = pcf->rtc;
294
295	if (rtc)
296		rtc_device_unregister(rtc);
297
298	if ((err = i2c_detach_client(client)))
299		return err;
300
301	kfree(pcf);
302	return 0;
303}
304
305static struct i2c_driver pcf8583_driver = {
306	.driver = {
307		.name	= "pcf8583",
308	},
309	.id		= I2C_DRIVERID_PCF8583,
310	.attach_adapter	= pcf8583_attach,
311	.detach_client	= pcf8583_detach,
312};
313
314static int pcf8583_probe(struct i2c_adapter *adap, int addr, int kind)
315{
316	struct pcf8583 *pcf;
317	struct i2c_client *client;
318	struct rtc_device *rtc;
319	unsigned char buf[1], ad[1] = { 0 };
320	int err;
321	struct i2c_msg msgs[2] = {
322		{
323			.addr = addr,
324			.flags = 0,
325			.len = 1,
326			.buf = ad,
327		}, {
328			.addr = addr,
329			.flags = I2C_M_RD,
330			.len = 1,
331			.buf = buf,
332		}
333	};
334
335	pcf = kzalloc(sizeof(*pcf), GFP_KERNEL);
336	if (!pcf)
337		return -ENOMEM;
338
339	client = &pcf->client;
340
341	client->addr		= addr;
342	client->adapter	= adap;
343	client->driver	= &pcf8583_driver;
344
345	strlcpy(client->name, pcf8583_driver.driver.name, I2C_NAME_SIZE);
346
347	if (i2c_transfer(client->adapter, msgs, 2) != 2) {
348		err = -EIO;
349		goto exit_kfree;
350	}
351
352	err = i2c_attach_client(client);
353
354	if (err)
355		goto exit_kfree;
356
357	rtc = rtc_device_register(pcf8583_driver.driver.name, &client->dev,
358				  &pcf8583_rtc_ops, THIS_MODULE);
359
360	if (IS_ERR(rtc)) {
361		err = PTR_ERR(rtc);
362		goto exit_detach;
363	}
364
365	pcf->rtc = rtc;
366	i2c_set_clientdata(client, pcf);
367	set_ctrl(client, buf[0]);
368
369	return 0;
370
371exit_detach:
372	i2c_detach_client(client);
373
374exit_kfree:
375	kfree(pcf);
376
377	return err;
378}
379
380static __init int pcf8583_init(void)
381{
382	return i2c_add_driver(&pcf8583_driver);
383}
384
385static __exit void pcf8583_exit(void)
386{
387	i2c_del_driver(&pcf8583_driver);
388}
389
390module_init(pcf8583_init);
391module_exit(pcf8583_exit);
392
393MODULE_AUTHOR("Russell King");
394MODULE_DESCRIPTION("PCF8583 I2C RTC driver");
395MODULE_LICENSE("GPL");
396