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linux/drivers/rtc/rtc-ds1307.c
David Brownell bd16f9ebd0 rtc-ds1307: typo fix found by coverity 
Fix a typo turned up by a Coverity check:  referring to the wrong register,
which could cause problems with DS1338 RTCs whose oscillators halted.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-26 11:35:16 -07:00

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/*
* rtc-ds1307.c - RTC driver for some mostly-compatible I2C chips.
*
* Copyright (C) 2005 James Chapman (ds1337 core)
* Copyright (C) 2006 David Brownell
*
* 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/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/string.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
/* We can't determine type by probing, but if we expect pre-Linux code
* to have set the chip up as a clock (turning on the oscillator and
* setting the date and time), Linux can ignore the non-clock features.
* That's a natural job for a factory or repair bench.
*
* This is currently a simple no-alarms driver. If your board has the
* alarm irq wired up on a ds1337 or ds1339, and you want to use that,
* then look at the rtc-rs5c372 driver for code to steal...
*/
enum ds_type {
ds_1307,
ds_1337,
ds_1338,
ds_1339,
ds_1340,
m41t00,
// rs5c372 too? different address...
};
/* RTC registers don't differ much, except for the century flag */
#define DS1307_REG_SECS 0x00 /* 00-59 */
# define DS1307_BIT_CH 0x80
# define DS1340_BIT_nEOSC 0x80
#define DS1307_REG_MIN 0x01 /* 00-59 */
#define DS1307_REG_HOUR 0x02 /* 00-23, or 1-12{am,pm} */
# define DS1307_BIT_12HR 0x40 /* in REG_HOUR */
# define DS1307_BIT_PM 0x20 /* in REG_HOUR */
# define DS1340_BIT_CENTURY_EN 0x80 /* in REG_HOUR */
# define DS1340_BIT_CENTURY 0x40 /* in REG_HOUR */
#define DS1307_REG_WDAY 0x03 /* 01-07 */
#define DS1307_REG_MDAY 0x04 /* 01-31 */
#define DS1307_REG_MONTH 0x05 /* 01-12 */
# define DS1337_BIT_CENTURY 0x80 /* in REG_MONTH */
#define DS1307_REG_YEAR 0x06 /* 00-99 */
/* Other registers (control, status, alarms, trickle charge, NVRAM, etc)
* start at 7, and they differ a LOT. Only control and status matter for
* basic RTC date and time functionality; be careful using them.
*/
#define DS1307_REG_CONTROL 0x07 /* or ds1338 */
# define DS1307_BIT_OUT 0x80
# define DS1338_BIT_OSF 0x20
# define DS1307_BIT_SQWE 0x10
# define DS1307_BIT_RS1 0x02
# define DS1307_BIT_RS0 0x01
#define DS1337_REG_CONTROL 0x0e
# define DS1337_BIT_nEOSC 0x80
# define DS1337_BIT_RS2 0x10
# define DS1337_BIT_RS1 0x08
# define DS1337_BIT_INTCN 0x04
# define DS1337_BIT_A2IE 0x02
# define DS1337_BIT_A1IE 0x01
#define DS1340_REG_CONTROL 0x07
# define DS1340_BIT_OUT 0x80
# define DS1340_BIT_FT 0x40
# define DS1340_BIT_CALIB_SIGN 0x20
# define DS1340_M_CALIBRATION 0x1f
#define DS1340_REG_FLAG 0x09
# define DS1340_BIT_OSF 0x80
#define DS1337_REG_STATUS 0x0f
# define DS1337_BIT_OSF 0x80
# define DS1337_BIT_A2I 0x02
# define DS1337_BIT_A1I 0x01
#define DS1339_REG_TRICKLE 0x10
struct ds1307 {
u8 reg_addr;
u8 regs[8];
enum ds_type type;
struct i2c_msg msg[2];
struct i2c_client *client;
struct i2c_client dev;
struct rtc_device *rtc;
};
struct chip_desc {
char name[9];
unsigned nvram56:1;
unsigned alarm:1;
enum ds_type type;
};
static const struct chip_desc chips[] = { {
.name = "ds1307",
.type = ds_1307,
.nvram56 = 1,
}, {
.name = "ds1337",
.type = ds_1337,
.alarm = 1,
}, {
.name = "ds1338",
.type = ds_1338,
.nvram56 = 1,
}, {
.name = "ds1339",
.type = ds_1339,
.alarm = 1,
}, {
.name = "ds1340",
.type = ds_1340,
}, {
.name = "m41t00",
.type = m41t00,
}, };
static inline const struct chip_desc *find_chip(const char *s)
{
unsigned i;
for (i = 0; i < ARRAY_SIZE(chips); i++)
if (strnicmp(s, chips[i].name, sizeof chips[i].name) == 0)
return &chips[i];
return NULL;
}
static int ds1307_get_time(struct device *dev, struct rtc_time *t)
{
struct ds1307 *ds1307 = dev_get_drvdata(dev);
int tmp;
/* read the RTC date and time registers all at once */
ds1307->msg[1].flags = I2C_M_RD;
ds1307->msg[1].len = 7;
tmp = i2c_transfer(to_i2c_adapter(ds1307->client->dev.parent),
ds1307->msg, 2);
if (tmp != 2) {
dev_err(dev, "%s error %d\n", "read", tmp);
return -EIO;
}
dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
"read",
ds1307->regs[0], ds1307->regs[1],
ds1307->regs[2], ds1307->regs[3],
ds1307->regs[4], ds1307->regs[5],
ds1307->regs[6]);
t->tm_sec = BCD2BIN(ds1307->regs[DS1307_REG_SECS] & 0x7f);
t->tm_min = BCD2BIN(ds1307->regs[DS1307_REG_MIN] & 0x7f);
tmp = ds1307->regs[DS1307_REG_HOUR] & 0x3f;
t->tm_hour = BCD2BIN(tmp);
t->tm_wday = BCD2BIN(ds1307->regs[DS1307_REG_WDAY] & 0x07) - 1;
t->tm_mday = BCD2BIN(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
tmp = ds1307->regs[DS1307_REG_MONTH] & 0x1f;
t->tm_mon = BCD2BIN(tmp) - 1;
/* assume 20YY not 19YY, and ignore DS1337_BIT_CENTURY */
t->tm_year = BCD2BIN(ds1307->regs[DS1307_REG_YEAR]) + 100;
dev_dbg(dev, "%s secs=%d, mins=%d, "
"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
"read", t->tm_sec, t->tm_min,
t->tm_hour, t->tm_mday,
t->tm_mon, t->tm_year, t->tm_wday);
/* initial clock setting can be undefined */
return rtc_valid_tm(t);
}
static int ds1307_set_time(struct device *dev, struct rtc_time *t)
{
struct ds1307 *ds1307 = dev_get_drvdata(dev);
int result;
int tmp;
u8 *buf = ds1307->regs;
dev_dbg(dev, "%s secs=%d, mins=%d, "
"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
"write", t->tm_sec, t->tm_min,
t->tm_hour, t->tm_mday,
t->tm_mon, t->tm_year, t->tm_wday);
*buf++ = 0; /* first register addr */
buf[DS1307_REG_SECS] = BIN2BCD(t->tm_sec);
buf[DS1307_REG_MIN] = BIN2BCD(t->tm_min);
buf[DS1307_REG_HOUR] = BIN2BCD(t->tm_hour);
buf[DS1307_REG_WDAY] = BIN2BCD(t->tm_wday + 1);
buf[DS1307_REG_MDAY] = BIN2BCD(t->tm_mday);
buf[DS1307_REG_MONTH] = BIN2BCD(t->tm_mon + 1);
/* assume 20YY not 19YY */
tmp = t->tm_year - 100;
buf[DS1307_REG_YEAR] = BIN2BCD(tmp);
switch (ds1307->type) {
case ds_1337:
case ds_1339:
buf[DS1307_REG_MONTH] |= DS1337_BIT_CENTURY;
break;
case ds_1340:
buf[DS1307_REG_HOUR] |= DS1340_BIT_CENTURY_EN
| DS1340_BIT_CENTURY;
break;
default:
break;
}
ds1307->msg[1].flags = 0;
ds1307->msg[1].len = 8;
dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
"write", buf[0], buf[1], buf[2], buf[3],
buf[4], buf[5], buf[6]);
result = i2c_transfer(to_i2c_adapter(ds1307->client->dev.parent),
&ds1307->msg[1], 1);
if (result != 1) {
dev_err(dev, "%s error %d\n", "write", tmp);
return -EIO;
}
return 0;
}
static const struct rtc_class_ops ds13xx_rtc_ops = {
.read_time = ds1307_get_time,
.set_time = ds1307_set_time,
};
static struct i2c_driver ds1307_driver;
static int __devinit ds1307_probe(struct i2c_client *client)
{
struct ds1307 *ds1307;
int err = -ENODEV;
int tmp;
const struct chip_desc *chip;
struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
chip = find_chip(client->name);
if (!chip) {
dev_err(&client->dev, "unknown chip type '%s'\n",
client->name);
return -ENODEV;
}
if (!i2c_check_functionality(adapter,
I2C_FUNC_I2C | I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
return -EIO;
if (!(ds1307 = kzalloc(sizeof(struct ds1307), GFP_KERNEL)))
return -ENOMEM;
ds1307->client = client;
i2c_set_clientdata(client, ds1307);
ds1307->msg[0].addr = client->addr;
ds1307->msg[0].flags = 0;
ds1307->msg[0].len = 1;
ds1307->msg[0].buf = &ds1307->reg_addr;
ds1307->msg[1].addr = client->addr;
ds1307->msg[1].flags = I2C_M_RD;
ds1307->msg[1].len = sizeof(ds1307->regs);
ds1307->msg[1].buf = ds1307->regs;
ds1307->type = chip->type;
switch (ds1307->type) {
case ds_1337:
case ds_1339:
ds1307->reg_addr = DS1337_REG_CONTROL;
ds1307->msg[1].len = 2;
/* get registers that the "rtc" read below won't read... */
tmp = i2c_transfer(adapter, ds1307->msg, 2);
if (tmp != 2) {
pr_debug("read error %d\n", tmp);
err = -EIO;
goto exit_free;
}
ds1307->reg_addr = 0;
ds1307->msg[1].len = sizeof(ds1307->regs);
/* oscillator off? turn it on, so clock can tick. */
if (ds1307->regs[0] & DS1337_BIT_nEOSC)
i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
ds1307->regs[0] & ~DS1337_BIT_nEOSC);
/* oscillator fault? clear flag, and warn */
if (ds1307->regs[1] & DS1337_BIT_OSF) {
i2c_smbus_write_byte_data(client, DS1337_REG_STATUS,
ds1307->regs[1] & ~DS1337_BIT_OSF);
dev_warn(&client->dev, "SET TIME!\n");
}
break;
default:
break;
}
read_rtc:
/* read RTC registers */
tmp = i2c_transfer(adapter, ds1307->msg, 2);
if (tmp != 2) {
pr_debug("read error %d\n", tmp);
err = -EIO;
goto exit_free;
}
/* minimal sanity checking; some chips (like DS1340) don't
* specify the extra bits as must-be-zero, but there are
* still a few values that are clearly out-of-range.
*/
tmp = ds1307->regs[DS1307_REG_SECS];
switch (ds1307->type) {
case ds_1340:
/* FIXME read register with DS1340_BIT_OSF, use that to
* trigger the "set time" warning (*after* restarting the
* oscillator!) instead of this weaker ds1307/m41t00 test.
*/
case ds_1307:
case m41t00:
/* clock halted? turn it on, so clock can tick. */
if (tmp & DS1307_BIT_CH) {
i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
dev_warn(&client->dev, "SET TIME!\n");
goto read_rtc;
}
break;
case ds_1338:
/* clock halted? turn it on, so clock can tick. */
if (tmp & DS1307_BIT_CH)
i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
/* oscillator fault? clear flag, and warn */
if (ds1307->regs[DS1307_REG_CONTROL] & DS1338_BIT_OSF) {
i2c_smbus_write_byte_data(client, DS1307_REG_CONTROL,
ds1307->regs[DS1307_REG_CONTROL]
& ~DS1338_BIT_OSF);
dev_warn(&client->dev, "SET TIME!\n");
goto read_rtc;
}
break;
case ds_1337:
case ds_1339:
break;
}
tmp = ds1307->regs[DS1307_REG_SECS];
tmp = BCD2BIN(tmp & 0x7f);
if (tmp > 60)
goto exit_bad;
tmp = BCD2BIN(ds1307->regs[DS1307_REG_MIN] & 0x7f);
if (tmp > 60)
goto exit_bad;
tmp = BCD2BIN(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
if (tmp == 0 || tmp > 31)
goto exit_bad;
tmp = BCD2BIN(ds1307->regs[DS1307_REG_MONTH] & 0x1f);
if (tmp == 0 || tmp > 12)
goto exit_bad;
tmp = ds1307->regs[DS1307_REG_HOUR];
switch (ds1307->type) {
case ds_1340:
case m41t00:
/* NOTE: ignores century bits; fix before deploying
* systems that will run through year 2100.
*/
break;
default:
if (!(tmp & DS1307_BIT_12HR))
break;
/* Be sure we're in 24 hour mode. Multi-master systems
* take note...
*/
tmp = BCD2BIN(tmp & 0x1f);
if (tmp == 12)
tmp = 0;
if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
tmp += 12;
i2c_smbus_write_byte_data(client,
DS1307_REG_HOUR,
BIN2BCD(tmp));
}
ds1307->rtc = rtc_device_register(client->name, &client->dev,
&ds13xx_rtc_ops, THIS_MODULE);
if (IS_ERR(ds1307->rtc)) {
err = PTR_ERR(ds1307->rtc);
dev_err(&client->dev,
"unable to register the class device\n");
goto exit_free;
}
return 0;
exit_bad:
dev_dbg(&client->dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
"bogus register",
ds1307->regs[0], ds1307->regs[1],
ds1307->regs[2], ds1307->regs[3],
ds1307->regs[4], ds1307->regs[5],
ds1307->regs[6]);
exit_free:
kfree(ds1307);
return err;
}
static int __devexit ds1307_remove(struct i2c_client *client)
{
struct ds1307 *ds1307 = i2c_get_clientdata(client);
rtc_device_unregister(ds1307->rtc);
kfree(ds1307);
return 0;
}
static struct i2c_driver ds1307_driver = {
.driver = {
.name = "rtc-ds1307",
.owner = THIS_MODULE,
},
.probe = ds1307_probe,
.remove = __devexit_p(ds1307_remove),
};
static int __init ds1307_init(void)
{
return i2c_add_driver(&ds1307_driver);
}
module_init(ds1307_init);
static void __exit ds1307_exit(void)
{
i2c_del_driver(&ds1307_driver);
}
module_exit(ds1307_exit);
MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
MODULE_LICENSE("GPL");
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