2 * I2C client/driver for the ST M41T80 family of i2c rtc chips.
4 * Author: Alexander Bigga <ab@mycable.de>
6 * Based on m41t00.c by Mark A. Greer <mgreer@mvista.com>
8 * 2006 (c) mycable GmbH
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18 #include <linux/bcd.h>
19 #include <linux/i2c.h>
20 #include <linux/init.h>
21 #include <linux/kernel.h>
22 #include <linux/module.h>
23 #include <linux/rtc.h>
24 #include <linux/slab.h>
25 #include <linux/mutex.h>
26 #include <linux/string.h>
27 #ifdef CONFIG_RTC_DRV_M41T80_WDT
29 #include <linux/ioctl.h>
30 #include <linux/miscdevice.h>
31 #include <linux/reboot.h>
32 #include <linux/watchdog.h>
35 #define M41T80_REG_SSEC 0
36 #define M41T80_REG_SEC 1
37 #define M41T80_REG_MIN 2
38 #define M41T80_REG_HOUR 3
39 #define M41T80_REG_WDAY 4
40 #define M41T80_REG_DAY 5
41 #define M41T80_REG_MON 6
42 #define M41T80_REG_YEAR 7
43 #define M41T80_REG_ALARM_MON 0xa
44 #define M41T80_REG_ALARM_DAY 0xb
45 #define M41T80_REG_ALARM_HOUR 0xc
46 #define M41T80_REG_ALARM_MIN 0xd
47 #define M41T80_REG_ALARM_SEC 0xe
48 #define M41T80_REG_FLAGS 0xf
49 #define M41T80_REG_SQW 0x13
51 #define M41T80_DATETIME_REG_SIZE (M41T80_REG_YEAR + 1)
52 #define M41T80_ALARM_REG_SIZE \
53 (M41T80_REG_ALARM_SEC + 1 - M41T80_REG_ALARM_MON)
55 #define M41T80_SEC_ST (1 << 7) /* ST: Stop Bit */
56 #define M41T80_ALMON_AFE (1 << 7) /* AFE: AF Enable Bit */
57 #define M41T80_ALMON_SQWE (1 << 6) /* SQWE: SQW Enable Bit */
58 #define M41T80_ALHOUR_HT (1 << 6) /* HT: Halt Update Bit */
59 #define M41T80_FLAGS_AF (1 << 6) /* AF: Alarm Flag Bit */
60 #define M41T80_FLAGS_BATT_LOW (1 << 4) /* BL: Battery Low Bit */
61 #define M41T80_WATCHDOG_RB2 (1 << 7) /* RB: Watchdog resolution */
62 #define M41T80_WATCHDOG_RB1 (1 << 1) /* RB: Watchdog resolution */
63 #define M41T80_WATCHDOG_RB0 (1 << 0) /* RB: Watchdog resolution */
65 #define M41T80_FEATURE_HT (1 << 0) /* Halt feature */
66 #define M41T80_FEATURE_BL (1 << 1) /* Battery low indicator */
67 #define M41T80_FEATURE_SQ (1 << 2) /* Squarewave feature */
68 #define M41T80_FEATURE_WD (1 << 3) /* Extra watchdog resolution */
69 #define M41T80_FEATURE_SQ_ALT (1 << 4) /* RSx bits are in reg 4 */
71 static DEFINE_MUTEX(m41t80_rtc_mutex);
72 static const struct i2c_device_id m41t80_id[] = {
73 { "m41t62", M41T80_FEATURE_SQ | M41T80_FEATURE_SQ_ALT },
74 { "m41t65", M41T80_FEATURE_HT | M41T80_FEATURE_WD },
75 { "m41t80", M41T80_FEATURE_SQ },
76 { "m41t81", M41T80_FEATURE_HT | M41T80_FEATURE_SQ},
77 { "m41t81s", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
78 { "m41t82", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
79 { "m41t83", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
80 { "m41st84", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
81 { "m41st85", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
82 { "m41st87", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
83 { "rv4162", M41T80_FEATURE_SQ | M41T80_FEATURE_WD | M41T80_FEATURE_SQ_ALT },
86 MODULE_DEVICE_TABLE(i2c, m41t80_id);
90 struct rtc_device *rtc;
93 static int m41t80_get_datetime(struct i2c_client *client,
96 u8 buf[M41T80_DATETIME_REG_SIZE], dt_addr[1] = { M41T80_REG_SEC };
97 struct i2c_msg msgs[] = {
105 .addr = client->addr,
107 .len = M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
108 .buf = buf + M41T80_REG_SEC,
112 if (i2c_transfer(client->adapter, msgs, 2) < 0) {
113 dev_err(&client->dev, "read error\n");
117 tm->tm_sec = bcd2bin(buf[M41T80_REG_SEC] & 0x7f);
118 tm->tm_min = bcd2bin(buf[M41T80_REG_MIN] & 0x7f);
119 tm->tm_hour = bcd2bin(buf[M41T80_REG_HOUR] & 0x3f);
120 tm->tm_mday = bcd2bin(buf[M41T80_REG_DAY] & 0x3f);
121 tm->tm_wday = buf[M41T80_REG_WDAY] & 0x07;
122 tm->tm_mon = bcd2bin(buf[M41T80_REG_MON] & 0x1f) - 1;
124 /* assume 20YY not 19YY, and ignore the Century Bit */
125 tm->tm_year = bcd2bin(buf[M41T80_REG_YEAR]) + 100;
126 return rtc_valid_tm(tm);
129 /* Sets the given date and time to the real time clock. */
130 static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm)
132 u8 wbuf[1 + M41T80_DATETIME_REG_SIZE];
134 u8 dt_addr[1] = { M41T80_REG_SEC };
135 struct i2c_msg msgs_in[] = {
137 .addr = client->addr,
143 .addr = client->addr,
145 .len = M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
146 .buf = buf + M41T80_REG_SEC,
149 struct i2c_msg msgs[] = {
151 .addr = client->addr,
153 .len = 1 + M41T80_DATETIME_REG_SIZE,
158 /* Read current reg values into buf[1..7] */
159 if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
160 dev_err(&client->dev, "read error\n");
164 wbuf[0] = 0; /* offset into rtc's regs */
165 /* Merge time-data and register flags into buf[0..7] */
166 buf[M41T80_REG_SSEC] = 0;
167 buf[M41T80_REG_SEC] =
168 bin2bcd(tm->tm_sec) | (buf[M41T80_REG_SEC] & ~0x7f);
169 buf[M41T80_REG_MIN] =
170 bin2bcd(tm->tm_min) | (buf[M41T80_REG_MIN] & ~0x7f);
171 buf[M41T80_REG_HOUR] =
172 bin2bcd(tm->tm_hour) | (buf[M41T80_REG_HOUR] & ~0x3f);
173 buf[M41T80_REG_WDAY] =
174 (tm->tm_wday & 0x07) | (buf[M41T80_REG_WDAY] & ~0x07);
175 buf[M41T80_REG_DAY] =
176 bin2bcd(tm->tm_mday) | (buf[M41T80_REG_DAY] & ~0x3f);
177 buf[M41T80_REG_MON] =
178 bin2bcd(tm->tm_mon + 1) | (buf[M41T80_REG_MON] & ~0x1f);
180 /* assume 20YY not 19YY */
181 if (tm->tm_year < 100 || tm->tm_year > 199) {
182 dev_err(&client->dev, "Year must be between 2000 and 2099. It's %d.\n",
186 buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year % 100);
188 if (i2c_transfer(client->adapter, msgs, 1) != 1) {
189 dev_err(&client->dev, "write error\n");
195 #if defined(CONFIG_RTC_INTF_PROC) || defined(CONFIG_RTC_INTF_PROC_MODULE)
196 static int m41t80_rtc_proc(struct device *dev, struct seq_file *seq)
198 struct i2c_client *client = to_i2c_client(dev);
199 struct m41t80_data *clientdata = i2c_get_clientdata(client);
202 if (clientdata->features & M41T80_FEATURE_BL) {
203 reg = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
204 seq_printf(seq, "battery\t\t: %s\n",
205 (reg & M41T80_FLAGS_BATT_LOW) ? "exhausted" : "ok");
210 #define m41t80_rtc_proc NULL
213 static int m41t80_rtc_read_time(struct device *dev, struct rtc_time *tm)
215 return m41t80_get_datetime(to_i2c_client(dev), tm);
218 static int m41t80_rtc_set_time(struct device *dev, struct rtc_time *tm)
220 return m41t80_set_datetime(to_i2c_client(dev), tm);
224 * XXX - m41t80 alarm functionality is reported broken.
225 * until it is fixed, don't register alarm functions.
227 static struct rtc_class_ops m41t80_rtc_ops = {
228 .read_time = m41t80_rtc_read_time,
229 .set_time = m41t80_rtc_set_time,
230 .proc = m41t80_rtc_proc,
233 #if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
234 static ssize_t m41t80_sysfs_show_flags(struct device *dev,
235 struct device_attribute *attr, char *buf)
237 struct i2c_client *client = to_i2c_client(dev);
240 val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
243 return sprintf(buf, "%#x\n", val);
245 static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
247 static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
248 struct device_attribute *attr, char *buf)
250 struct i2c_client *client = to_i2c_client(dev);
251 struct m41t80_data *clientdata = i2c_get_clientdata(client);
254 if (!(clientdata->features & M41T80_FEATURE_SQ))
257 reg_sqw = M41T80_REG_SQW;
258 if (clientdata->features & M41T80_FEATURE_SQ_ALT)
259 reg_sqw = M41T80_REG_WDAY;
260 val = i2c_smbus_read_byte_data(client, reg_sqw);
263 val = (val >> 4) & 0xf;
273 return sprintf(buf, "%d\n", val);
275 static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
276 struct device_attribute *attr,
277 const char *buf, size_t count)
279 struct i2c_client *client = to_i2c_client(dev);
280 struct m41t80_data *clientdata = i2c_get_clientdata(client);
281 int almon, sqw, reg_sqw, rc;
282 int val = simple_strtoul(buf, NULL, 0);
284 if (!(clientdata->features & M41T80_FEATURE_SQ))
288 if (!is_power_of_2(val))
298 /* disable SQW, set SQW frequency & re-enable */
299 almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
302 reg_sqw = M41T80_REG_SQW;
303 if (clientdata->features & M41T80_FEATURE_SQ_ALT)
304 reg_sqw = M41T80_REG_WDAY;
305 sqw = i2c_smbus_read_byte_data(client, reg_sqw);
308 sqw = (sqw & 0x0f) | (val << 4);
310 rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
311 almon & ~M41T80_ALMON_SQWE);
316 rc = i2c_smbus_write_byte_data(client, reg_sqw, sqw);
320 rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
321 almon | M41T80_ALMON_SQWE);
327 static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
328 m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
330 static struct attribute *attrs[] = {
331 &dev_attr_flags.attr,
332 &dev_attr_sqwfreq.attr,
335 static struct attribute_group attr_group = {
339 static int m41t80_sysfs_register(struct device *dev)
341 return sysfs_create_group(&dev->kobj, &attr_group);
344 static int m41t80_sysfs_register(struct device *dev)
350 #ifdef CONFIG_RTC_DRV_M41T80_WDT
352 *****************************************************************************
356 *****************************************************************************
358 static struct i2c_client *save_client;
361 #define WD_TIMO 60 /* 1..31 seconds */
363 static int wdt_margin = WD_TIMO;
364 module_param(wdt_margin, int, 0);
365 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
367 static unsigned long wdt_is_open;
368 static int boot_flag;
373 * Reload counter one with the watchdog timeout. We don't bother reloading
374 * the cascade counter.
376 static void wdt_ping(void)
378 unsigned char i2c_data[2];
379 struct i2c_msg msgs1[1] = {
381 .addr = save_client->addr,
387 struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
389 i2c_data[0] = 0x09; /* watchdog register */
392 i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
395 * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
397 i2c_data[1] = wdt_margin<<2 | 0x82;
400 * M41T65 has three bits for watchdog resolution. Don't set bit 7, as
401 * that would be an invalid resolution.
403 if (clientdata->features & M41T80_FEATURE_WD)
404 i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
406 i2c_transfer(save_client->adapter, msgs1, 1);
414 static void wdt_disable(void)
416 unsigned char i2c_data[2], i2c_buf[0x10];
417 struct i2c_msg msgs0[2] = {
419 .addr = save_client->addr,
425 .addr = save_client->addr,
431 struct i2c_msg msgs1[1] = {
433 .addr = save_client->addr,
441 i2c_transfer(save_client->adapter, msgs0, 2);
445 i2c_transfer(save_client->adapter, msgs1, 1);
450 * @file: file handle to the watchdog
451 * @buf: buffer to write (unused as data does not matter here
452 * @count: count of bytes
453 * @ppos: pointer to the position to write. No seeks allowed
455 * A write to a watchdog device is defined as a keepalive signal. Any
456 * write of data will do, as we we don't define content meaning.
458 static ssize_t wdt_write(struct file *file, const char __user *buf,
459 size_t count, loff_t *ppos)
468 static ssize_t wdt_read(struct file *file, char __user *buf,
469 size_t count, loff_t *ppos)
476 * @inode: inode of the device
477 * @file: file handle to the device
478 * @cmd: watchdog command
479 * @arg: argument pointer
481 * The watchdog API defines a common set of functions for all watchdogs
482 * according to their available features. We only actually usefully support
483 * querying capabilities and current status.
485 static int wdt_ioctl(struct file *file, unsigned int cmd,
489 static struct watchdog_info ident = {
490 .options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
492 .firmware_version = 1,
493 .identity = "M41T80 WTD"
497 case WDIOC_GETSUPPORT:
498 return copy_to_user((struct watchdog_info __user *)arg, &ident,
499 sizeof(ident)) ? -EFAULT : 0;
501 case WDIOC_GETSTATUS:
502 case WDIOC_GETBOOTSTATUS:
503 return put_user(boot_flag, (int __user *)arg);
504 case WDIOC_KEEPALIVE:
507 case WDIOC_SETTIMEOUT:
508 if (get_user(new_margin, (int __user *)arg))
510 /* Arbitrary, can't find the card's limits */
511 if (new_margin < 1 || new_margin > 124)
513 wdt_margin = new_margin;
516 case WDIOC_GETTIMEOUT:
517 return put_user(wdt_margin, (int __user *)arg);
519 case WDIOC_SETOPTIONS:
520 if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
523 if (rv & WDIOS_DISABLECARD) {
524 pr_info("disable watchdog\n");
528 if (rv & WDIOS_ENABLECARD) {
529 pr_info("enable watchdog\n");
538 static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
543 mutex_lock(&m41t80_rtc_mutex);
544 ret = wdt_ioctl(file, cmd, arg);
545 mutex_unlock(&m41t80_rtc_mutex);
552 * @inode: inode of device
553 * @file: file handle to device
556 static int wdt_open(struct inode *inode, struct file *file)
558 if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
559 mutex_lock(&m41t80_rtc_mutex);
560 if (test_and_set_bit(0, &wdt_is_open)) {
561 mutex_unlock(&m41t80_rtc_mutex);
568 mutex_unlock(&m41t80_rtc_mutex);
569 return nonseekable_open(inode, file);
576 * @inode: inode to board
577 * @file: file handle to board
580 static int wdt_release(struct inode *inode, struct file *file)
582 if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
583 clear_bit(0, &wdt_is_open);
589 * @this: our notifier block
590 * @code: the event being reported
593 * Our notifier is called on system shutdowns. We want to turn the card
594 * off at reboot otherwise the machine will reboot again during memory
595 * test or worse yet during the following fsck. This would suck, in fact
596 * trust me - if it happens it does suck.
598 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
601 if (code == SYS_DOWN || code == SYS_HALT)
602 /* Disable Watchdog */
607 static const struct file_operations wdt_fops = {
608 .owner = THIS_MODULE,
610 .unlocked_ioctl = wdt_unlocked_ioctl,
613 .release = wdt_release,
617 static struct miscdevice wdt_dev = {
618 .minor = WATCHDOG_MINOR,
624 * The WDT card needs to learn about soft shutdowns in order to
625 * turn the timebomb registers off.
627 static struct notifier_block wdt_notifier = {
628 .notifier_call = wdt_notify_sys,
630 #endif /* CONFIG_RTC_DRV_M41T80_WDT */
633 *****************************************************************************
637 *****************************************************************************
639 static int m41t80_probe(struct i2c_client *client,
640 const struct i2c_device_id *id)
643 struct rtc_device *rtc = NULL;
645 struct m41t80_data *clientdata = NULL;
647 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
648 | I2C_FUNC_SMBUS_BYTE_DATA))
651 clientdata = devm_kzalloc(&client->dev, sizeof(*clientdata),
656 clientdata->features = id->driver_data;
657 i2c_set_clientdata(client, clientdata);
659 rtc = devm_rtc_device_register(&client->dev, client->name,
660 &m41t80_rtc_ops, THIS_MODULE);
664 clientdata->rtc = rtc;
666 /* Make sure HT (Halt Update) bit is cleared */
667 rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
669 if (rc >= 0 && rc & M41T80_ALHOUR_HT) {
670 if (clientdata->features & M41T80_FEATURE_HT) {
671 m41t80_get_datetime(client, &tm);
672 dev_info(&client->dev, "HT bit was set!\n");
673 dev_info(&client->dev,
675 "%04i-%02i-%02i %02i:%02i:%02i\n",
677 tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
678 tm.tm_min, tm.tm_sec);
680 rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_HOUR,
681 rc & ~M41T80_ALHOUR_HT);
685 dev_err(&client->dev, "Can't clear HT bit\n");
689 /* Make sure ST (stop) bit is cleared */
690 rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
692 if (rc >= 0 && rc & M41T80_SEC_ST)
693 rc = i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
694 rc & ~M41T80_SEC_ST);
696 dev_err(&client->dev, "Can't clear ST bit\n");
700 rc = m41t80_sysfs_register(&client->dev);
704 #ifdef CONFIG_RTC_DRV_M41T80_WDT
705 if (clientdata->features & M41T80_FEATURE_HT) {
706 save_client = client;
707 rc = misc_register(&wdt_dev);
710 rc = register_reboot_notifier(&wdt_notifier);
712 misc_deregister(&wdt_dev);
720 static int m41t80_remove(struct i2c_client *client)
722 #ifdef CONFIG_RTC_DRV_M41T80_WDT
723 struct m41t80_data *clientdata = i2c_get_clientdata(client);
725 if (clientdata->features & M41T80_FEATURE_HT) {
726 misc_deregister(&wdt_dev);
727 unregister_reboot_notifier(&wdt_notifier);
734 static struct i2c_driver m41t80_driver = {
736 .name = "rtc-m41t80",
738 .probe = m41t80_probe,
739 .remove = m41t80_remove,
740 .id_table = m41t80_id,
743 module_i2c_driver(m41t80_driver);
745 MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
746 MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
747 MODULE_LICENSE("GPL");