1/*
2 * An SPI driver for the Philips PCF2123 RTC
3 * Copyright 2009 Cyber Switching, Inc.
4 *
5 * Author: Chris Verges <chrisv@cyberswitching.com>
6 * Maintainers: http://www.cyberswitching.com
7 *
8 * based on the RS5C348 driver in this same directory.
9 *
10 * Thanks to Christian Pellegrin <chripell@fsfe.org> for
11 * the sysfs contributions to this driver.
12 *
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License version 2 as
15 * published by the Free Software Foundation.
16 *
17 * Please note that the CS is active high, so platform data
18 * should look something like:
19 *
20 * static struct spi_board_info ek_spi_devices[] = {
21 *	...
22 *	{
23 *		.modalias		= "rtc-pcf2123",
24 *		.chip_select		= 1,
25 *		.controller_data	= (void *)AT91_PIN_PA10,
26 *		.max_speed_hz		= 1000 * 1000,
27 *		.mode			= SPI_CS_HIGH,
28 *		.bus_num		= 0,
29 *	},
30 *	...
31 *};
32 *
33 */
34
35#include <linux/bcd.h>
36#include <linux/delay.h>
37#include <linux/device.h>
38#include <linux/errno.h>
39#include <linux/init.h>
40#include <linux/kernel.h>
41#include <linux/of.h>
42#include <linux/string.h>
43#include <linux/slab.h>
44#include <linux/rtc.h>
45#include <linux/spi/spi.h>
46#include <linux/module.h>
47#include <linux/sysfs.h>
48
49#define DRV_VERSION "0.6"
50
51#define PCF2123_REG_CTRL1	(0x00)	/* Control Register 1 */
52#define PCF2123_REG_CTRL2	(0x01)	/* Control Register 2 */
53#define PCF2123_REG_SC		(0x02)	/* datetime */
54#define PCF2123_REG_MN		(0x03)
55#define PCF2123_REG_HR		(0x04)
56#define PCF2123_REG_DM		(0x05)
57#define PCF2123_REG_DW		(0x06)
58#define PCF2123_REG_MO		(0x07)
59#define PCF2123_REG_YR		(0x08)
60
61#define PCF2123_SUBADDR		(1 << 4)
62#define PCF2123_WRITE		((0 << 7) | PCF2123_SUBADDR)
63#define PCF2123_READ		((1 << 7) | PCF2123_SUBADDR)
64
65static struct spi_driver pcf2123_driver;
66
67struct pcf2123_sysfs_reg {
68	struct device_attribute attr;
69	char name[2];
70};
71
72struct pcf2123_plat_data {
73	struct rtc_device *rtc;
74	struct pcf2123_sysfs_reg regs[16];
75};
76
77/*
78 * Causes a 30 nanosecond delay to ensure that the PCF2123 chip select
79 * is released properly after an SPI write.  This function should be
80 * called after EVERY read/write call over SPI.
81 */
82static inline void pcf2123_delay_trec(void)
83{
84	ndelay(30);
85}
86
87static ssize_t pcf2123_show(struct device *dev, struct device_attribute *attr,
88			    char *buffer)
89{
90	struct spi_device *spi = to_spi_device(dev);
91	struct pcf2123_sysfs_reg *r;
92	u8 txbuf[1], rxbuf[1];
93	unsigned long reg;
94	int ret;
95
96	r = container_of(attr, struct pcf2123_sysfs_reg, attr);
97
98	ret = kstrtoul(r->name, 16, &reg);
99	if (ret)
100		return ret;
101
102	txbuf[0] = PCF2123_READ | reg;
103	ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
104	if (ret < 0)
105		return -EIO;
106	pcf2123_delay_trec();
107	return sprintf(buffer, "0x%x\n", rxbuf[0]);
108}
109
110static ssize_t pcf2123_store(struct device *dev, struct device_attribute *attr,
111			     const char *buffer, size_t count) {
112	struct spi_device *spi = to_spi_device(dev);
113	struct pcf2123_sysfs_reg *r;
114	u8 txbuf[2];
115	unsigned long reg;
116	unsigned long val;
117
118	int ret;
119
120	r = container_of(attr, struct pcf2123_sysfs_reg, attr);
121
122	ret = kstrtoul(r->name, 16, &reg);
123	if (ret)
124		return ret;
125
126	ret = kstrtoul(buffer, 10, &val);
127	if (ret)
128		return ret;
129
130	txbuf[0] = PCF2123_WRITE | reg;
131	txbuf[1] = val;
132	ret = spi_write(spi, txbuf, sizeof(txbuf));
133	if (ret < 0)
134		return -EIO;
135	pcf2123_delay_trec();
136	return count;
137}
138
139static int pcf2123_rtc_read_time(struct device *dev, struct rtc_time *tm)
140{
141	struct spi_device *spi = to_spi_device(dev);
142	u8 txbuf[1], rxbuf[7];
143	int ret;
144
145	txbuf[0] = PCF2123_READ | PCF2123_REG_SC;
146	ret = spi_write_then_read(spi, txbuf, sizeof(txbuf),
147			rxbuf, sizeof(rxbuf));
148	if (ret < 0)
149		return ret;
150	pcf2123_delay_trec();
151
152	tm->tm_sec = bcd2bin(rxbuf[0] & 0x7F);
153	tm->tm_min = bcd2bin(rxbuf[1] & 0x7F);
154	tm->tm_hour = bcd2bin(rxbuf[2] & 0x3F); /* rtc hr 0-23 */
155	tm->tm_mday = bcd2bin(rxbuf[3] & 0x3F);
156	tm->tm_wday = rxbuf[4] & 0x07;
157	tm->tm_mon = bcd2bin(rxbuf[5] & 0x1F) - 1; /* rtc mn 1-12 */
158	tm->tm_year = bcd2bin(rxbuf[6]);
159	if (tm->tm_year < 70)
160		tm->tm_year += 100;	/* assume we are in 1970...2069 */
161
162	dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
163			"mday=%d, mon=%d, year=%d, wday=%d\n",
164			__func__,
165			tm->tm_sec, tm->tm_min, tm->tm_hour,
166			tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
167
168	/* the clock can give out invalid datetime, but we cannot return
169	 * -EINVAL otherwise hwclock will refuse to set the time on bootup.
170	 */
171	if (rtc_valid_tm(tm) < 0)
172		dev_err(dev, "retrieved date/time is not valid.\n");
173
174	return 0;
175}
176
177static int pcf2123_rtc_set_time(struct device *dev, struct rtc_time *tm)
178{
179	struct spi_device *spi = to_spi_device(dev);
180	u8 txbuf[8];
181	int ret;
182
183	dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
184			"mday=%d, mon=%d, year=%d, wday=%d\n",
185			__func__,
186			tm->tm_sec, tm->tm_min, tm->tm_hour,
187			tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
188
189	/* Stop the counter first */
190	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
191	txbuf[1] = 0x20;
192	ret = spi_write(spi, txbuf, 2);
193	if (ret < 0)
194		return ret;
195	pcf2123_delay_trec();
196
197	/* Set the new time */
198	txbuf[0] = PCF2123_WRITE | PCF2123_REG_SC;
199	txbuf[1] = bin2bcd(tm->tm_sec & 0x7F);
200	txbuf[2] = bin2bcd(tm->tm_min & 0x7F);
201	txbuf[3] = bin2bcd(tm->tm_hour & 0x3F);
202	txbuf[4] = bin2bcd(tm->tm_mday & 0x3F);
203	txbuf[5] = tm->tm_wday & 0x07;
204	txbuf[6] = bin2bcd((tm->tm_mon + 1) & 0x1F); /* rtc mn 1-12 */
205	txbuf[7] = bin2bcd(tm->tm_year < 100 ? tm->tm_year : tm->tm_year - 100);
206
207	ret = spi_write(spi, txbuf, sizeof(txbuf));
208	if (ret < 0)
209		return ret;
210	pcf2123_delay_trec();
211
212	/* Start the counter */
213	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
214	txbuf[1] = 0x00;
215	ret = spi_write(spi, txbuf, 2);
216	if (ret < 0)
217		return ret;
218	pcf2123_delay_trec();
219
220	return 0;
221}
222
223static const struct rtc_class_ops pcf2123_rtc_ops = {
224	.read_time	= pcf2123_rtc_read_time,
225	.set_time	= pcf2123_rtc_set_time,
226};
227
228static int pcf2123_probe(struct spi_device *spi)
229{
230	struct rtc_device *rtc;
231	struct pcf2123_plat_data *pdata;
232	u8 txbuf[2], rxbuf[2];
233	int ret, i;
234
235	pdata = devm_kzalloc(&spi->dev, sizeof(struct pcf2123_plat_data),
236				GFP_KERNEL);
237	if (!pdata)
238		return -ENOMEM;
239	spi->dev.platform_data = pdata;
240
241	/* Send a software reset command */
242	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
243	txbuf[1] = 0x58;
244	dev_dbg(&spi->dev, "resetting RTC (0x%02X 0x%02X)\n",
245			txbuf[0], txbuf[1]);
246	ret = spi_write(spi, txbuf, 2 * sizeof(u8));
247	if (ret < 0)
248		goto kfree_exit;
249	pcf2123_delay_trec();
250
251	/* Stop the counter */
252	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
253	txbuf[1] = 0x20;
254	dev_dbg(&spi->dev, "stopping RTC (0x%02X 0x%02X)\n",
255			txbuf[0], txbuf[1]);
256	ret = spi_write(spi, txbuf, 2 * sizeof(u8));
257	if (ret < 0)
258		goto kfree_exit;
259	pcf2123_delay_trec();
260
261	/* See if the counter was actually stopped */
262	txbuf[0] = PCF2123_READ | PCF2123_REG_CTRL1;
263	dev_dbg(&spi->dev, "checking for presence of RTC (0x%02X)\n",
264			txbuf[0]);
265	ret = spi_write_then_read(spi, txbuf, 1 * sizeof(u8),
266					rxbuf, 2 * sizeof(u8));
267	dev_dbg(&spi->dev, "received data from RTC (0x%02X 0x%02X)\n",
268			rxbuf[0], rxbuf[1]);
269	if (ret < 0)
270		goto kfree_exit;
271	pcf2123_delay_trec();
272
273	if (!(rxbuf[0] & 0x20)) {
274		dev_err(&spi->dev, "chip not found\n");
275		ret = -ENODEV;
276		goto kfree_exit;
277	}
278
279	dev_info(&spi->dev, "chip found, driver version " DRV_VERSION "\n");
280	dev_info(&spi->dev, "spiclk %u KHz.\n",
281			(spi->max_speed_hz + 500) / 1000);
282
283	/* Start the counter */
284	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
285	txbuf[1] = 0x00;
286	ret = spi_write(spi, txbuf, sizeof(txbuf));
287	if (ret < 0)
288		goto kfree_exit;
289	pcf2123_delay_trec();
290
291	/* Finalize the initialization */
292	rtc = devm_rtc_device_register(&spi->dev, pcf2123_driver.driver.name,
293			&pcf2123_rtc_ops, THIS_MODULE);
294
295	if (IS_ERR(rtc)) {
296		dev_err(&spi->dev, "failed to register.\n");
297		ret = PTR_ERR(rtc);
298		goto kfree_exit;
299	}
300
301	pdata->rtc = rtc;
302
303	for (i = 0; i < 16; i++) {
304		sysfs_attr_init(&pdata->regs[i].attr.attr);
305		sprintf(pdata->regs[i].name, "%1x", i);
306		pdata->regs[i].attr.attr.mode = S_IRUGO | S_IWUSR;
307		pdata->regs[i].attr.attr.name = pdata->regs[i].name;
308		pdata->regs[i].attr.show = pcf2123_show;
309		pdata->regs[i].attr.store = pcf2123_store;
310		ret = device_create_file(&spi->dev, &pdata->regs[i].attr);
311		if (ret) {
312			dev_err(&spi->dev, "Unable to create sysfs %s\n",
313				pdata->regs[i].name);
314			goto sysfs_exit;
315		}
316	}
317
318	return 0;
319
320sysfs_exit:
321	for (i--; i >= 0; i--)
322		device_remove_file(&spi->dev, &pdata->regs[i].attr);
323
324kfree_exit:
325	spi->dev.platform_data = NULL;
326	return ret;
327}
328
329static int pcf2123_remove(struct spi_device *spi)
330{
331	struct pcf2123_plat_data *pdata = dev_get_platdata(&spi->dev);
332	int i;
333
334	if (pdata) {
335		for (i = 0; i < 16; i++)
336			if (pdata->regs[i].name[0])
337				device_remove_file(&spi->dev,
338						   &pdata->regs[i].attr);
339	}
340
341	return 0;
342}
343
344#ifdef CONFIG_OF
345static const struct of_device_id pcf2123_dt_ids[] = {
346	{ .compatible = "nxp,rtc-pcf2123", },
347	{ /* sentinel */ }
348};
349MODULE_DEVICE_TABLE(of, pcf2123_dt_ids);
350#endif
351
352static struct spi_driver pcf2123_driver = {
353	.driver	= {
354			.name	= "rtc-pcf2123",
355			.owner	= THIS_MODULE,
356			.of_match_table = of_match_ptr(pcf2123_dt_ids),
357	},
358	.probe	= pcf2123_probe,
359	.remove	= pcf2123_remove,
360};
361
362module_spi_driver(pcf2123_driver);
363
364MODULE_AUTHOR("Chris Verges <chrisv@cyberswitching.com>");
365MODULE_DESCRIPTION("NXP PCF2123 RTC driver");
366MODULE_LICENSE("GPL");
367MODULE_VERSION(DRV_VERSION);
368