Root/drivers/rtc/rtc-pcf2123.c

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

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