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[PATCH] rtc-pcf8563: detect polarity of century bit automatically

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The usage of the century bit was inverted on 2.6.19 following to PCF8563's
description, but it was not match to usage suggested by RTC8564's
datasheet.  Anyway what MO_C=1 means can vary on each platform.  This patch
is to detect its polarity in get_datetime routine.  The default value of
c_polarity is 0 (MO_C=1 means 19xx) so that this patch does not change
current behavior even if get_datetime was not called before set_datetime.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Jean-Baptiste Maneyrol <jean-baptiste.maneyrol@teamlog.com>
Cc: <stable@kernel.org>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Atsushi Nemoto 2007-02-08 14:20:24 -08:00 committed by Linus Torvalds
parent 68a696a01f
commit cbb9450234
1 changed files with 34 additions and 6 deletions
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40
drivers/rtc/rtc-pcf8563.c
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@ -53,6 +53,25 @@ I2C_CLIENT_INSMOD;
#define PCF8563_SC_LV 0x80 /* low voltage */
#define PCF8563_MO_C 0x80 /* century */
struct pcf8563 {
struct i2c_client client;
/*
* The meaning of MO_C bit varies by the chip type.
* From PCF8563 datasheet: this bit is toggled when the years
* register overflows from 99 to 00
* 0 indicates the century is 20xx
* 1 indicates the century is 19xx
* From RTC8564 datasheet: this bit indicates change of
* century. When the year digit data overflows from 99 to 00,
* this bit is set. By presetting it to 0 while still in the
* 20th century, it will be set in year 2000, ...
* There seems no reliable way to know how the system use this
* bit. So let's do it heuristically, assuming we are live in
* 1970...2069.
*/
int c_polarity; /* 0: MO_C=1 means 19xx, otherwise MO_C=1 means 20xx */
};
static int pcf8563_probe(struct i2c_adapter *adapter, int address, int kind);
static int pcf8563_detach(struct i2c_client *client);
@ -62,6 +81,7 @@ static int pcf8563_detach(struct i2c_client *client);
*/
static int pcf8563_get_datetime(struct i2c_client *client, struct rtc_time *tm)
{
struct pcf8563 *pcf8563 = container_of(client, struct pcf8563, client);
unsigned char buf[13] = { PCF8563_REG_ST1 };
struct i2c_msg msgs[] = {
@ -94,8 +114,12 @@ static int pcf8563_get_datetime(struct i2c_client *client, struct rtc_time *tm)
tm->tm_mday = BCD2BIN(buf[PCF8563_REG_DM] & 0x3F);
tm->tm_wday = buf[PCF8563_REG_DW] & 0x07;
tm->tm_mon = BCD2BIN(buf[PCF8563_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
tm->tm_year = BCD2BIN(buf[PCF8563_REG_YR])
+ (buf[PCF8563_REG_MO] & PCF8563_MO_C ? 0 : 100);
tm->tm_year = BCD2BIN(buf[PCF8563_REG_YR]);
if (tm->tm_year < 70)
tm->tm_year += 100; /* assume we are in 1970...2069 */
/* detect the polarity heuristically. see note above. */
pcf8563->c_polarity = (buf[PCF8563_REG_MO] & PCF8563_MO_C) ?
(tm->tm_year >= 100) : (tm->tm_year < 100);
dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
"mday=%d, mon=%d, year=%d, wday=%d\n",
@ -114,6 +138,7 @@ static int pcf8563_get_datetime(struct i2c_client *client, struct rtc_time *tm)
static int pcf8563_set_datetime(struct i2c_client *client, struct rtc_time *tm)
{
struct pcf8563 *pcf8563 = container_of(client, struct pcf8563, client);
int i, err;
unsigned char buf[9];
@ -135,7 +160,7 @@ static int pcf8563_set_datetime(struct i2c_client *client, struct rtc_time *tm)
/* year and century */
buf[PCF8563_REG_YR] = BIN2BCD(tm->tm_year % 100);
if (tm->tm_year < 100)
if (pcf8563->c_polarity ? (tm->tm_year >= 100) : (tm->tm_year < 100))
buf[PCF8563_REG_MO] |= PCF8563_MO_C;
buf[PCF8563_REG_DW] = tm->tm_wday & 0x07;
@ -248,6 +273,7 @@ static struct i2c_driver pcf8563_driver = {
static int pcf8563_probe(struct i2c_adapter *adapter, int address, int kind)
{
struct pcf8563 *pcf8563;
struct i2c_client *client;
struct rtc_device *rtc;
@ -260,11 +286,12 @@ static int pcf8563_probe(struct i2c_adapter *adapter, int address, int kind)
goto exit;
}
if (!(client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL))) {
if (!(pcf8563 = kzalloc(sizeof(struct pcf8563), GFP_KERNEL))) {
err = -ENOMEM;
goto exit;
}
client = &pcf8563->client;
client->addr = address;
client->driver = &pcf8563_driver;
client->adapter = adapter;
@ -301,7 +328,7 @@ exit_detach:
i2c_detach_client(client);
exit_kfree:
kfree(client);
kfree(pcf8563);
exit:
return err;
@ -309,6 +336,7 @@ exit:
static int pcf8563_detach(struct i2c_client *client)
{
struct pcf8563 *pcf8563 = container_of(client, struct pcf8563, client);
int err;
struct rtc_device *rtc = i2c_get_clientdata(client);
@ -318,7 +346,7 @@ static int pcf8563_detach(struct i2c_client *client)
if ((err = i2c_detach_client(client)))
return err;
kfree(client);
kfree(pcf8563);
return 0;
}