1/*
  2 * Copyright (C) 2012 Avionic Design GmbH
  3 *
  4 * This program is free software; you can redistribute it and/or modify
  5 * it under the terms of the GNU General Public License version 2 as
  6 * published by the Free Software Foundation.
  7 */
  8
  9#include <linux/bcd.h>
 10#include <linux/i2c.h>
 11#include <linux/module.h>
 12#include <linux/rtc.h>
 13#include <linux/of.h>
 14
 15#define DRIVER_NAME "rtc-pcf8523"
 16
 17#define REG_CONTROL1 0x00
 18#define REG_CONTROL1_CAP_SEL (1 << 7)
 19#define REG_CONTROL1_STOP    (1 << 5)
 20
 21#define REG_CONTROL3 0x02
 22#define REG_CONTROL3_PM_BLD (1 << 7) /* battery low detection disabled */
 23#define REG_CONTROL3_PM_VDD (1 << 6) /* switch-over disabled */
 24#define REG_CONTROL3_PM_DSM (1 << 5) /* direct switching mode */
 25#define REG_CONTROL3_PM_MASK 0xe0
 26#define REG_CONTROL3_BLF (1 << 2) /* battery low bit, read-only */
 27
 28#define REG_SECONDS  0x03
 29#define REG_SECONDS_OS (1 << 7)
 30
 31#define REG_MINUTES  0x04
 32#define REG_HOURS    0x05
 33#define REG_DAYS     0x06
 34#define REG_WEEKDAYS 0x07
 35#define REG_MONTHS   0x08
 36#define REG_YEARS    0x09
 37
 38struct pcf8523 {
 39	struct rtc_device *rtc;
 40};
 41
 42static int pcf8523_read(struct i2c_client *client, u8 reg, u8 *valuep)
 43{
 44	struct i2c_msg msgs[2];
 45	u8 value = 0;
 46	int err;
 47
 48	msgs[0].addr = client->addr;
 49	msgs[0].flags = 0;
 50	msgs[0].len = sizeof(reg);
 51	msgs[0].buf = &reg;
 52
 53	msgs[1].addr = client->addr;
 54	msgs[1].flags = I2C_M_RD;
 55	msgs[1].len = sizeof(value);
 56	msgs[1].buf = &value;
 57
 58	err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
 59	if (err < 0)
 60		return err;
 61
 62	*valuep = value;
 63
 64	return 0;
 65}
 66
 67static int pcf8523_write(struct i2c_client *client, u8 reg, u8 value)
 68{
 69	u8 buffer[2] = { reg, value };
 70	struct i2c_msg msg;
 71	int err;
 72
 73	msg.addr = client->addr;
 74	msg.flags = 0;
 75	msg.len = sizeof(buffer);
 76	msg.buf = buffer;
 77
 78	err = i2c_transfer(client->adapter, &msg, 1);
 79	if (err < 0)
 80		return err;
 81
 82	return 0;
 83}
 84
 85static int pcf8523_select_capacitance(struct i2c_client *client, bool high)
 86{
 87	u8 value;
 88	int err;
 89
 90	err = pcf8523_read(client, REG_CONTROL1, &value);
 91	if (err < 0)
 92		return err;
 93
 94	if (!high)
 95		value &= ~REG_CONTROL1_CAP_SEL;
 96	else
 97		value |= REG_CONTROL1_CAP_SEL;
 98
 99	err = pcf8523_write(client, REG_CONTROL1, value);
100	if (err < 0)
101		return err;
102
103	return err;
104}
105
106static int pcf8523_set_pm(struct i2c_client *client, u8 pm)
107{
108	u8 value;
109	int err;
110
111	err = pcf8523_read(client, REG_CONTROL3, &value);
112	if (err < 0)
113		return err;
114
115	value = (value & ~REG_CONTROL3_PM_MASK) | pm;
116
117	err = pcf8523_write(client, REG_CONTROL3, value);
118	if (err < 0)
119		return err;
120
121	return 0;
122}
123
124static int pcf8523_stop_rtc(struct i2c_client *client)
125{
126	u8 value;
127	int err;
128
129	err = pcf8523_read(client, REG_CONTROL1, &value);
130	if (err < 0)
131		return err;
132
133	value |= REG_CONTROL1_STOP;
134
135	err = pcf8523_write(client, REG_CONTROL1, value);
136	if (err < 0)
137		return err;
138
139	return 0;
140}
141
142static int pcf8523_start_rtc(struct i2c_client *client)
143{
144	u8 value;
145	int err;
146
147	err = pcf8523_read(client, REG_CONTROL1, &value);
148	if (err < 0)
149		return err;
150
151	value &= ~REG_CONTROL1_STOP;
152
153	err = pcf8523_write(client, REG_CONTROL1, value);
154	if (err < 0)
155		return err;
156
157	return 0;
158}
159
160static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm)
161{
162	struct i2c_client *client = to_i2c_client(dev);
163	u8 start = REG_SECONDS, regs[7];
164	struct i2c_msg msgs[2];
165	int err;
166
167	msgs[0].addr = client->addr;
168	msgs[0].flags = 0;
169	msgs[0].len = 1;
170	msgs[0].buf = &start;
171
172	msgs[1].addr = client->addr;
173	msgs[1].flags = I2C_M_RD;
174	msgs[1].len = sizeof(regs);
175	msgs[1].buf = regs;
176
177	err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
178	if (err < 0)
179		return err;
180
181	if (regs[0] & REG_SECONDS_OS) {
182		/*
183		 * If the oscillator was stopped, try to clear the flag. Upon
184		 * power-up the flag is always set, but if we cannot clear it
185		 * the oscillator isn't running properly for some reason. The
186		 * sensible thing therefore is to return an error, signalling
187		 * that the clock cannot be assumed to be correct.
188		 */
189
190		regs[0] &= ~REG_SECONDS_OS;
191
192		err = pcf8523_write(client, REG_SECONDS, regs[0]);
193		if (err < 0)
194			return err;
195
196		err = pcf8523_read(client, REG_SECONDS, &regs[0]);
197		if (err < 0)
198			return err;
199
200		if (regs[0] & REG_SECONDS_OS)
201			return -EAGAIN;
202	}
203
204	tm->tm_sec = bcd2bin(regs[0] & 0x7f);
205	tm->tm_min = bcd2bin(regs[1] & 0x7f);
206	tm->tm_hour = bcd2bin(regs[2] & 0x3f);
207	tm->tm_mday = bcd2bin(regs[3] & 0x3f);
208	tm->tm_wday = regs[4] & 0x7;
209	tm->tm_mon = bcd2bin(regs[5] & 0x1f) - 1;
210	tm->tm_year = bcd2bin(regs[6]) + 100;
211
212	return rtc_valid_tm(tm);
213}
214
215static int pcf8523_rtc_set_time(struct device *dev, struct rtc_time *tm)
216{
217	struct i2c_client *client = to_i2c_client(dev);
218	struct i2c_msg msg;
219	u8 regs[8];
220	int err;
221
222	err = pcf8523_stop_rtc(client);
223	if (err < 0)
224		return err;
225
226	regs[0] = REG_SECONDS;
227	regs[1] = bin2bcd(tm->tm_sec);
228	regs[2] = bin2bcd(tm->tm_min);
229	regs[3] = bin2bcd(tm->tm_hour);
230	regs[4] = bin2bcd(tm->tm_mday);
231	regs[5] = tm->tm_wday;
232	regs[6] = bin2bcd(tm->tm_mon + 1);
233	regs[7] = bin2bcd(tm->tm_year - 100);
234
235	msg.addr = client->addr;
236	msg.flags = 0;
237	msg.len = sizeof(regs);
238	msg.buf = regs;
239
240	err = i2c_transfer(client->adapter, &msg, 1);
241	if (err < 0) {
242		/*
243		 * If the time cannot be set, restart the RTC anyway. Note
244		 * that errors are ignored if the RTC cannot be started so
245		 * that we have a chance to propagate the original error.
246		 */
247		pcf8523_start_rtc(client);
248		return err;
249	}
250
251	return pcf8523_start_rtc(client);
252}
253
254#ifdef CONFIG_RTC_INTF_DEV
255static int pcf8523_rtc_ioctl(struct device *dev, unsigned int cmd,
256			     unsigned long arg)
257{
258	struct i2c_client *client = to_i2c_client(dev);
259	u8 value;
260	int ret = 0, err;
261
262	switch (cmd) {
263	case RTC_VL_READ:
264		err = pcf8523_read(client, REG_CONTROL3, &value);
265		if (err < 0)
266			return err;
267
268		if (value & REG_CONTROL3_BLF)
269			ret = 1;
270
271		if (copy_to_user((void __user *)arg, &ret, sizeof(int)))
272			return -EFAULT;
273
274		return 0;
275	default:
276		return -ENOIOCTLCMD;
277	}
278}
279#else
280#define pcf8523_rtc_ioctl NULL
281#endif
282
283static const struct rtc_class_ops pcf8523_rtc_ops = {
284	.read_time = pcf8523_rtc_read_time,
285	.set_time = pcf8523_rtc_set_time,
286	.ioctl = pcf8523_rtc_ioctl,
287};
288
289static int pcf8523_probe(struct i2c_client *client,
290			 const struct i2c_device_id *id)
291{
292	struct pcf8523 *pcf;
293	int err;
294
295	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
296		return -ENODEV;
297
298	pcf = devm_kzalloc(&client->dev, sizeof(*pcf), GFP_KERNEL);
299	if (!pcf)
300		return -ENOMEM;
301
302	err = pcf8523_select_capacitance(client, true);
303	if (err < 0)
304		return err;
305
306	err = pcf8523_set_pm(client, 0);
307	if (err < 0)
308		return err;
309
310	pcf->rtc = devm_rtc_device_register(&client->dev, DRIVER_NAME,
311				       &pcf8523_rtc_ops, THIS_MODULE);
312	if (IS_ERR(pcf->rtc))
313		return PTR_ERR(pcf->rtc);
314
315	i2c_set_clientdata(client, pcf);
316
317	return 0;
318}
319
320static const struct i2c_device_id pcf8523_id[] = {
321	{ "pcf8523", 0 },
322	{ }
323};
324MODULE_DEVICE_TABLE(i2c, pcf8523_id);
325
326#ifdef CONFIG_OF
327static const struct of_device_id pcf8523_of_match[] = {
328	{ .compatible = "nxp,pcf8523" },
329	{ }
330};
331MODULE_DEVICE_TABLE(of, pcf8523_of_match);
332#endif
333
334static struct i2c_driver pcf8523_driver = {
335	.driver = {
336		.name = DRIVER_NAME,
337		.owner = THIS_MODULE,
338		.of_match_table = of_match_ptr(pcf8523_of_match),
339	},
340	.probe = pcf8523_probe,
341	.id_table = pcf8523_id,
342};
343module_i2c_driver(pcf8523_driver);
344
345MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
346MODULE_DESCRIPTION("NXP PCF8523 RTC driver");
347MODULE_LICENSE("GPL v2");