/*
* I2C client/driver for the ST M41T80 family of i2c rtc chips.
*
* Author: Alexander Bigga <ab@mycable.de>
*
* Based on m41t00.c by Mark A. Greer <mgreer@mvista.com>
*
* 2006 (c) mycable GmbH
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#include <linux/bcd.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/string.h>
#ifdef CONFIG_RTC_DRV_M41T80_WDT
#include <linux/fs.h>
#include <linux/ioctl.h>
#include <linux/miscdevice.h>
#include <linux/reboot.h>
#include <linux/watchdog.h>
#endif
#define M41T80_REG_SSEC 0
#define M41T80_REG_SEC 1
#define M41T80_REG_MIN 2
#define M41T80_REG_HOUR 3
#define M41T80_REG_WDAY 4
#define M41T80_REG_DAY 5
#define M41T80_REG_MON 6
#define M41T80_REG_YEAR 7
#define M41T80_REG_ALARM_MON 0xa
#define M41T80_REG_ALARM_DAY 0xb
#define M41T80_REG_ALARM_HOUR 0xc
#define M41T80_REG_ALARM_MIN 0xd
#define M41T80_REG_ALARM_SEC 0xe
#define M41T80_REG_FLAGS 0xf
#define M41T80_REG_SQW 0x13
#define M41T80_DATETIME_REG_SIZE (M41T80_REG_YEAR + 1)
#define M41T80_ALARM_REG_SIZE \
(M41T80_REG_ALARM_SEC + 1 - M41T80_REG_ALARM_MON)
#define M41T80_SEC_ST (1 << 7) /* ST: Stop Bit */
#define M41T80_ALMON_AFE (1 << 7) /* AFE: AF Enable Bit */
#define M41T80_ALMON_SQWE (1 << 6) /* SQWE: SQW Enable Bit */
#define M41T80_ALHOUR_HT (1 << 6) /* HT: Halt Update Bit */
#define M41T80_FLAGS_AF (1 << 6) /* AF: Alarm Flag Bit */
#define M41T80_FLAGS_BATT_LOW (1 << 4) /* BL: Battery Low Bit */
#define M41T80_WATCHDOG_RB2 (1 << 7) /* RB: Watchdog resolution */
#define M41T80_WATCHDOG_RB1 (1 << 1) /* RB: Watchdog resolution */
#define M41T80_WATCHDOG_RB0 (1 << 0) /* RB: Watchdog resolution */
#define M41T80_FEATURE_HT (1 << 0) /* Halt feature */
#define M41T80_FEATURE_BL (1 << 1) /* Battery low indicator */
#define M41T80_FEATURE_SQ (1 << 2) /* Squarewave feature */
#define M41T80_FEATURE_WD (1 << 3) /* Extra watchdog resolution */
#define M41T80_FEATURE_SQ_ALT (1 << 4) /* RSx bits are in reg 4 */
#define DRV_VERSION "0.05"
static DEFINE_MUTEX(m41t80_rtc_mutex);
static const struct i2c_device_id m41t80_id[] = {
{ "m41t62", M41T80_FEATURE_SQ | M41T80_FEATURE_SQ_ALT },
{ "m41t65", M41T80_FEATURE_HT | M41T80_FEATURE_WD },
{ "m41t80", M41T80_FEATURE_SQ },
{ "m41t81", M41T80_FEATURE_HT | M41T80_FEATURE_SQ},
{ "m41t81s", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
{ "m41t82", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
{ "m41t83", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
{ "m41st84", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
{ "m41st85", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
{ "m41st87", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
{ }
};
MODULE_DEVICE_TABLE(i2c, m41t80_id);
struct m41t80_data {
u8 features;
struct rtc_device *rtc;
};
static int m41t80_get_datetime(struct i2c_client *client,
struct rtc_time *tm)
{
u8 buf[M41T80_DATETIME_REG_SIZE], dt_addr[1] = { M41T80_REG_SEC };
struct i2c_msg msgs[] = {
{
.addr = client->addr,
.flags = 0,
.len = 1,
.buf = dt_addr,
},
{
.addr = client->addr,
.flags = I2C_M_RD,
.len = M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
.buf = buf + M41T80_REG_SEC,
},
};
if (i2c_transfer(client->adapter, msgs, 2) < 0) {
dev_err(&client->dev, "read error\n");
return -EIO;
}
tm->tm_sec = bcd2bin(buf[M41T80_REG_SEC] & 0x7f);
tm->tm_min = bcd2bin(buf[M41T80_REG_MIN] & 0x7f);
tm->tm_hour = bcd2bin(buf[M41T80_REG_HOUR] & 0x3f);
tm->tm_mday = bcd2bin(buf[M41T80_REG_DAY] & 0x3f);
tm->tm_wday = buf[M41T80_REG_WDAY] & 0x07;
tm->tm_mon = bcd2bin(buf[M41T80_REG_MON] & 0x1f) - 1;
/* assume 20YY not 19YY, and ignore the Century Bit */
tm->tm_year = bcd2bin(buf[M41T80_REG_YEAR]) + 100;
return rtc_valid_tm(tm);
}
/* Sets the given date and time to the real time clock. */
static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm)
{
u8 wbuf[1 + M41T80_DATETIME_REG_SIZE];
u8 *buf = &wbuf[1];
u8 dt_addr[1] = { M41T80_REG_SEC };
struct i2c_msg msgs_in[] = {
{
.addr = client->addr,
.flags = 0,
.len = 1,
.buf = dt_addr,
},
{
.addr = client->addr,
.flags = I2C_M_RD,
.len = M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
.buf = buf + M41T80_REG_SEC,
},
};
struct i2c_msg msgs[] = {
{
.addr = client->addr,
.flags = 0,
.len = 1 + M41T80_DATETIME_REG_SIZE,
.buf = wbuf,
},
};
/* Read current reg values into buf[1..7] */
if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
dev_err(&client->dev, "read error\n");
return -EIO;
}
wbuf[0] = 0; /* offset into rtc's regs */
/* Merge time-data and register flags into buf[0..7] */
buf[M41T80_REG_SSEC] = 0;
buf[M41T80_REG_SEC] =
bin2bcd(tm->tm_sec) | (buf[M41T80_REG_SEC] & ~0x7f);
buf[M41T80_REG_MIN] =
bin2bcd(tm->tm_min) | (buf[M41T80_REG_MIN] & ~0x7f);
buf[M41T80_REG_HOUR] =
bin2bcd(tm->tm_hour) | (buf[M41T80_REG_HOUR] & ~0x3f);
buf[M41T80_REG_WDAY] =
(tm->tm_wday & 0x07) | (buf[M41T80_REG_WDAY] & ~0x07);
buf[M41T80_REG_DAY] =
bin2bcd(tm->tm_mday) | (buf[M41T80_REG_DAY] & ~0x3f);
buf[M41T80_REG_MON] =
bin2bcd(tm->tm_mon + 1) | (buf[M41T80_REG_MON] & ~0x1f);
/* assume 20YY not 19YY */
buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year % 100);
if (i2c_transfer(client->adapter, msgs, 1) != 1) {
dev_err(&client->dev, "write error\n");
return -EIO;
}
return 0;
}
#if defined(CONFIG_RTC_INTF_PROC) || defined(CONFIG_RTC_INTF_PROC_MODULE)
static int m41t80_rtc_proc(struct device *dev, struct seq_file *seq)
{
struct i2c_client *client = to_i2c_client(dev);
struct m41t80_data *clientdata = i2c_get_clientdata(client);
u8 reg;
if (clientdata->features & M41T80_FEATURE_BL) {
reg = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
seq_printf(seq, "battery\t\t: %s\n",
(reg & M41T80_FLAGS_BATT_LOW) ? "exhausted" : "ok");
}
return 0;
}
#else
#define m41t80_rtc_proc NULL
#endif
static int m41t80_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
return m41t80_get_datetime(to_i2c_client(dev), tm);
}
static int m41t80_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
return m41t80_set_datetime(to_i2c_client(dev), tm);
}
/*
* XXX - m41t80 alarm functionality is reported broken.
* until it is fixed, don't register alarm functions.
*/
static struct rtc_class_ops m41t80_rtc_ops = {
.read_time = m41t80_rtc_read_time,
.set_time = m41t80_rtc_set_time,
.proc = m41t80_rtc_proc,
};
#if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
static ssize_t m41t80_sysfs_show_flags(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct i2c_client *client = to_i2c_client(dev);
int val;
val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
if (val < 0)
return -EIO;
return sprintf(buf, "%#x\n", val);
}
static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct i2c_client *client = to_i2c_client(dev);
struct m41t80_data *clientdata = i2c_get_clientdata(client);
int val, reg_sqw;
if (!(clientdata->features & M41T80_FEATURE_SQ))
return -EINVAL;
reg_sqw = M41T80_REG_SQW;
if (clientdata->features & M41T80_FEATURE_SQ_ALT)
reg_sqw = M41T80_REG_WDAY;
val = i2c_smbus_read_byte_data(client, reg_sqw);
if (val < 0)
return -EIO;
val = (val >> 4) & 0xf;
switch (val) {
case 0:
break;
case 1:
val = 32768;
break;
default:
val = 32768 >> val;
}
return sprintf(buf, "%d\n", val);
}
static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct i2c_client *client = to_i2c_client(dev);
struct m41t80_data *clientdata = i2c_get_clientdata(client);
int almon, sqw, reg_sqw;
int val = simple_strtoul(buf, NULL, 0);
if (!(clientdata->features & M41T80_FEATURE_SQ))
return -EINVAL;
if (val) {
if (!is_power_of_2(val))
return -EINVAL;
val = ilog2(val);
if (val == 15)
val = 1;
else if (val < 14)
val = 15 - val;
else
return -EINVAL;
}
/* disable SQW, set SQW frequency & re-enable */
almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
if (almon < 0)
return -EIO;
reg_sqw = M41T80_REG_SQW;
if (clientdata->features & M41T80_FEATURE_SQ_ALT)
reg_sqw = M41T80_REG_WDAY;
sqw = i2c_smbus_read_byte_data(client, reg_sqw);
if (sqw < 0)
return -EIO;
sqw = (sqw & 0x0f) | (val << 4);
if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
almon & ~M41T80_ALMON_SQWE) < 0 ||
i2c_smbus_write_byte_data(client, reg_sqw, sqw) < 0)
return -EIO;
if (val && i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
almon | M41T80_ALMON_SQWE) < 0)
return -EIO;
return count;
}
static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
static struct attribute *attrs[] = {
&dev_attr_flags.attr,
&dev_attr_sqwfreq.attr,
NULL,
};
static struct attribute_group attr_group = {
.attrs = attrs,
};
static int m41t80_sysfs_register(struct device *dev)
{
return sysfs_create_group(&dev->kobj, &attr_group);
}
#else
static int m41t80_sysfs_register(struct device *dev)
{
return 0;
}
#endif
#ifdef CONFIG_RTC_DRV_M41T80_WDT
/*
*****************************************************************************
*
* Watchdog Driver
*
*****************************************************************************
*/
static struct i2c_client *save_client;
/* Default margin */
#define WD_TIMO 60 /* 1..31 seconds */
static int wdt_margin = WD_TIMO;
module_param(wdt_margin, int, 0);
MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
static unsigned long wdt_is_open;
static int boot_flag;
/**
* wdt_ping:
*
* Reload counter one with the watchdog timeout. We don't bother reloading
* the cascade counter.
*/
static void wdt_ping(void)
{
unsigned char i2c_data[2];
struct i2c_msg msgs1[1] = {
{
.addr = save_client->addr,
.flags = 0,
.len = 2,
.buf = i2c_data,
},
};
struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
i2c_data[0] = 0x09; /* watchdog register */
if (wdt_margin > 31)
i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
else
/*
* WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
*/
i2c_data[1] = wdt_margin<<2 | 0x82;
/*
* M41T65 has three bits for watchdog resolution. Don't set bit 7, as
* that would be an invalid resolution.
*/
if (clientdata->features & M41T80_FEATURE_WD)
i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
i2c_transfer(save_client->adapter, msgs1, 1);
}
/**
* wdt_disable:
*
* disables watchdog.
*/
static void wdt_disable(void)
{
unsigned char i2c_data[2], i2c_buf[0x10];
struct i2c_msg msgs0[2] = {
{
.addr = save_client->addr,
.flags = 0,
.len = 1,
.buf = i2c_data,
},
{
.addr = save_client->addr,
.flags = I2C_M_RD,
.len = 1,
.buf = i2c_buf,
},
};
struct i2c_msg msgs1[1] = {
{
.addr = save_client->addr,
.flags = 0,
.len = 2,
.buf = i2c_data,
},
};
i2c_data[0] = 0x09;
i2c_transfer(save_client->adapter, msgs0, 2);
i2c_data[0] = 0x09;
i2c_data[1] = 0x00;
i2c_transfer(save_client->adapter, msgs1, 1);
}
/**
* wdt_write:
* @file: file handle to the watchdog
* @buf: buffer to write (unused as data does not matter here
* @count: count of bytes
* @ppos: pointer to the position to write. No seeks allowed
*
* A write to a watchdog device is defined as a keepalive signal. Any
* write of data will do, as we we don't define content meaning.
*/
static ssize_t wdt_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
if (count) {
wdt_ping();
return 1;
}
return 0;
}
static ssize_t wdt_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
return 0;
}
/**
* wdt_ioctl:
* @inode: inode of the device
* @file: file handle to the device
* @cmd: watchdog command
* @arg: argument pointer
*
* The watchdog API defines a common set of functions for all watchdogs
* according to their available features. We only actually usefully support
* querying capabilities and current status.
*/
static int wdt_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
int new_margin, rv;
static struct watchdog_info ident = {
.options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
WDIOF_SETTIMEOUT,
.firmware_version = 1,
.identity = "M41T80 WTD"
};
switch (cmd) {
case WDIOC_GETSUPPORT:
return copy_to_user((struct watchdog_info __user *)arg, &ident,
sizeof(ident)) ? -EFAULT : 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(boot_flag, (int __user *)arg);
case WDIOC_KEEPALIVE:
wdt_ping();
return 0;
case WDIOC_SETTIMEOUT:
if (get_user(new_margin, (int __user *)arg))
return -EFAULT;
/* Arbitrary, can't find the card's limits */
if (new_margin < 1 || new_margin > 124)
return -EINVAL;
wdt_margin = new_margin;
wdt_ping();
/* Fall */
case WDIOC_GETTIMEOUT:
return put_user(wdt_margin, (int __user *)arg);
case WDIOC_SETOPTIONS:
if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
return -EFAULT;
if (rv & WDIOS_DISABLECARD) {
pr_info("rtc-m41t80: disable watchdog\n");
wdt_disable();
}
if (rv & WDIOS_ENABLECARD) {
pr_info("rtc-m41t80: enable watchdog\n");
wdt_ping();
}
return -EINVAL;
}
return -ENOTTY;
}
static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
int ret;
mutex_lock(&m41t80_rtc_mutex);
ret = wdt_ioctl(file, cmd, arg);
mutex_unlock(&m41t80_rtc_mutex);
return ret;
}
/**
* wdt_open:
* @inode: inode of device
* @file: file handle to device
*
*/
static int wdt_open(struct inode *inode, struct file *file)
{
if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
mutex_lock(&m41t80_rtc_mutex);
if (test_and_set_bit(0, &wdt_is_open)) {
mutex_unlock(&m41t80_rtc_mutex);
return -EBUSY;
}
/*
* Activate
*/
wdt_is_open = 1;
mutex_unlock(&m41t80_rtc_mutex);
return nonseekable_open(inode, file);
}
return -ENODEV;
}
/**
* wdt_close:
* @inode: inode to board
* @file: file handle to board
*
*/
static int wdt_release(struct inode *inode, struct file *file)
{
if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
clear_bit(0, &wdt_is_open);
return 0;
}
/**
* notify_sys:
* @this: our notifier block
* @code: the event being reported
* @unused: unused
*
* Our notifier is called on system shutdowns. We want to turn the card
* off at reboot otherwise the machine will reboot again during memory
* test or worse yet during the following fsck. This would suck, in fact
* trust me - if it happens it does suck.
*/
static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
void *unused)
{
if (code == SYS_DOWN || code == SYS_HALT)
/* Disable Watchdog */
wdt_disable();
return NOTIFY_DONE;
}
static const struct file_operations wdt_fops = {
.owner = THIS_MODULE,
.read = wdt_read,
.unlocked_ioctl = wdt_unlocked_ioctl,
.write = wdt_write,
.open = wdt_open,
.release = wdt_release,
.llseek = no_llseek,
};
static struct miscdevice wdt_dev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &wdt_fops,
};
/*
* The WDT card needs to learn about soft shutdowns in order to
* turn the timebomb registers off.
*/
static struct notifier_block wdt_notifier = {
.notifier_call = wdt_notify_sys,
};
#endif /* CONFIG_RTC_DRV_M41T80_WDT */
/*
*****************************************************************************
*
* Driver Interface
*
*****************************************************************************
*/
static int m41t80_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
int rc = 0;
struct rtc_device *rtc = NULL;
struct rtc_time tm;
struct m41t80_data *clientdata = NULL;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
| I2C_FUNC_SMBUS_BYTE_DATA)) {
rc = -ENODEV;
goto exit;
}
dev_info(&client->dev,
"chip found, driver version " DRV_VERSION "\n");
clientdata = devm_kzalloc(&client->dev, sizeof(*clientdata),
GFP_KERNEL);
if (!clientdata) {
rc = -ENOMEM;
goto exit;
}
clientdata->features = id->driver_data;
i2c_set_clientdata(client, clientdata);
rtc = devm_rtc_device_register(&client->dev, client->name,
&m41t80_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc)) {
rc = PTR_ERR(rtc);
rtc = NULL;
goto exit;
}
clientdata->rtc = rtc;
/* Make sure HT (Halt Update) bit is cleared */
rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
if (rc < 0)
goto ht_err;
if (rc & M41T80_ALHOUR_HT) {
if (clientdata->features & M41T80_FEATURE_HT) {
m41t80_get_datetime(client, &tm);
dev_info(&client->dev, "HT bit was set!\n");
dev_info(&client->dev,
"Power Down at "
"%04i-%02i-%02i %02i:%02i:%02i\n",
tm.tm_year + 1900,
tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
tm.tm_min, tm.tm_sec);
}
if (i2c_smbus_write_byte_data(client,
M41T80_REG_ALARM_HOUR,
rc & ~M41T80_ALHOUR_HT) < 0)
goto ht_err;
}
/* Make sure ST (stop) bit is cleared */
rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
if (rc < 0)
goto st_err;
if (rc & M41T80_SEC_ST) {
if (i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
rc & ~M41T80_SEC_ST) < 0)
goto st_err;
}
rc = m41t80_sysfs_register(&client->dev);
if (rc)
goto exit;
#ifdef CONFIG_RTC_DRV_M41T80_WDT
if (clientdata->features & M41T80_FEATURE_HT) {
save_client = client;
rc = misc_register(&wdt_dev);
if (rc)
goto exit;
rc = register_reboot_notifier(&wdt_notifier);
if (rc) {
misc_deregister(&wdt_dev);
goto exit;
}
}
#endif
return 0;
st_err:
rc = -EIO;
dev_err(&client->dev, "Can't clear ST bit\n");
goto exit;
ht_err:
rc = -EIO;
dev_err(&client->dev, "Can't clear HT bit\n");
goto exit;
exit:
return rc;
}
static int m41t80_remove(struct i2c_client *client)
{
#ifdef CONFIG_RTC_DRV_M41T80_WDT
struct m41t80_data *clientdata = i2c_get_clientdata(client);
if (clientdata->features & M41T80_FEATURE_HT) {
misc_deregister(&wdt_dev);
unregister_reboot_notifier(&wdt_notifier);
}
#endif
return 0;
}
static struct i2c_driver m41t80_driver = {
.driver = {
.name = "rtc-m41t80",
},
.probe = m41t80_probe,
.remove = m41t80_remove,
.id_table = m41t80_id,
};
module_i2c_driver(m41t80_driver);
MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);
