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linux/drivers/rtc/rtc-s35390a.c
Uwe Kleine-König 3bd32722c8 rtc: s35390a: improve irq handling 
On some QNAP NAS devices the rtc can wake the machine. Several people
noticed that once the machine was woken this way it fails to shut down.
That's because the driver fails to acknowledge the interrupt and so it
keeps active and restarts the machine immediatly after shutdown. See
https://bugs.debian.org/794266 for a bug report.

Doing this correctly requires to interpret the INT2 flag of the first read
of the STATUS1 register because this bit is cleared by read.

Note this is not maximally robust though because a pending irq isn't
detected when the STATUS1 register was already read (and so INT2 is not
set) but the irq was not disabled. But that is a hardware imposed problem
that cannot easily be fixed by software.

Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
2016-07-11 23:22:34 +02:00

516 lines
12 KiB
C
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/*
* Seiko Instruments S-35390A RTC Driver
*
* Copyright (c) 2007 Byron Bradley
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/i2c.h>
#include <linux/bitrev.h>
#include <linux/bcd.h>
#include <linux/slab.h>
#include <linux/delay.h>
#define S35390A_CMD_STATUS1 0
#define S35390A_CMD_STATUS2 1
#define S35390A_CMD_TIME1 2
#define S35390A_CMD_TIME2 3
#define S35390A_CMD_INT2_REG1 5
#define S35390A_BYTE_YEAR 0
#define S35390A_BYTE_MONTH 1
#define S35390A_BYTE_DAY 2
#define S35390A_BYTE_WDAY 3
#define S35390A_BYTE_HOURS 4
#define S35390A_BYTE_MINS 5
#define S35390A_BYTE_SECS 6
#define S35390A_ALRM_BYTE_WDAY 0
#define S35390A_ALRM_BYTE_HOURS 1
#define S35390A_ALRM_BYTE_MINS 2
/* flags for STATUS1 */
#define S35390A_FLAG_POC 0x01
#define S35390A_FLAG_BLD 0x02
#define S35390A_FLAG_INT2 0x04
#define S35390A_FLAG_24H 0x40
#define S35390A_FLAG_RESET 0x80
/* flag for STATUS2 */
#define S35390A_FLAG_TEST 0x01
#define S35390A_INT2_MODE_MASK 0xF0
#define S35390A_INT2_MODE_NOINTR 0x00
#define S35390A_INT2_MODE_FREQ 0x10
#define S35390A_INT2_MODE_ALARM 0x40
#define S35390A_INT2_MODE_PMIN_EDG 0x20
static const struct i2c_device_id s35390a_id[] = {
{ "s35390a", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, s35390a_id);
struct s35390a {
struct i2c_client *client[8];
struct rtc_device *rtc;
int twentyfourhour;
};
static int s35390a_set_reg(struct s35390a *s35390a, int reg, char *buf, int len)
{
struct i2c_client *client = s35390a->client[reg];
struct i2c_msg msg[] = {
{
.addr = client->addr,
.len = len,
.buf = buf
},
};
if ((i2c_transfer(client->adapter, msg, 1)) != 1)
return -EIO;
return 0;
}
static int s35390a_get_reg(struct s35390a *s35390a, int reg, char *buf, int len)
{
struct i2c_client *client = s35390a->client[reg];
struct i2c_msg msg[] = {
{
.addr = client->addr,
.flags = I2C_M_RD,
.len = len,
.buf = buf
},
};
if ((i2c_transfer(client->adapter, msg, 1)) != 1)
return -EIO;
return 0;
}
/*
* Returns <0 on error, 0 if rtc is setup fine and 1 if the chip was reset.
* To keep the information if an irq is pending, pass the value read from
* STATUS1 to the caller.
*/
static int s35390a_reset(struct s35390a *s35390a, char *status1)
{
char buf;
int ret;
unsigned initcount = 0;
ret = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, status1, 1);
if (ret < 0)
return ret;
if (*status1 & S35390A_FLAG_POC)
/*
* Do not communicate for 0.5 seconds since the power-on
* detection circuit is in operation.
*/
msleep(500);
else if (!(*status1 & S35390A_FLAG_BLD))
/*
* If both POC and BLD are unset everything is fine.
*/
return 0;
/*
* At least one of POC and BLD are set, so reinitialise chip. Keeping
* this information in the hardware to know later that the time isn't
* valid is unfortunately not possible because POC and BLD are cleared
* on read. So the reset is best done now.
*
* The 24H bit is kept over reset, so set it already here.
*/
initialize:
*status1 = S35390A_FLAG_24H;
buf = S35390A_FLAG_RESET | S35390A_FLAG_24H;
ret = s35390a_set_reg(s35390a, S35390A_CMD_STATUS1, &buf, 1);
if (ret < 0)
return ret;
ret = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, &buf, 1);
if (ret < 0)
return ret;
if (buf & (S35390A_FLAG_POC | S35390A_FLAG_BLD)) {
/* Try up to five times to reset the chip */
if (initcount < 5) {
++initcount;
goto initialize;
} else
return -EIO;
}
return 1;
}
static int s35390a_disable_test_mode(struct s35390a *s35390a)
{
char buf[1];
if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf)) < 0)
return -EIO;
if (!(buf[0] & S35390A_FLAG_TEST))
return 0;
buf[0] &= ~S35390A_FLAG_TEST;
return s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf));
}
static char s35390a_hr2reg(struct s35390a *s35390a, int hour)
{
if (s35390a->twentyfourhour)
return bin2bcd(hour);
if (hour < 12)
return bin2bcd(hour);
return 0x40 | bin2bcd(hour - 12);
}
static int s35390a_reg2hr(struct s35390a *s35390a, char reg)
{
unsigned hour;
if (s35390a->twentyfourhour)
return bcd2bin(reg & 0x3f);
hour = bcd2bin(reg & 0x3f);
if (reg & 0x40)
hour += 12;
return hour;
}
static int s35390a_set_datetime(struct i2c_client *client, struct rtc_time *tm)
{
struct s35390a *s35390a = i2c_get_clientdata(client);
int i, err;
char buf[7];
dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d mday=%d, "
"mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
tm->tm_wday);
buf[S35390A_BYTE_YEAR] = bin2bcd(tm->tm_year - 100);
buf[S35390A_BYTE_MONTH] = bin2bcd(tm->tm_mon + 1);
buf[S35390A_BYTE_DAY] = bin2bcd(tm->tm_mday);
buf[S35390A_BYTE_WDAY] = bin2bcd(tm->tm_wday);
buf[S35390A_BYTE_HOURS] = s35390a_hr2reg(s35390a, tm->tm_hour);
buf[S35390A_BYTE_MINS] = bin2bcd(tm->tm_min);
buf[S35390A_BYTE_SECS] = bin2bcd(tm->tm_sec);
/* This chip expects the bits of each byte to be in reverse order */
for (i = 0; i < 7; ++i)
buf[i] = bitrev8(buf[i]);
err = s35390a_set_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
return err;
}
static int s35390a_get_datetime(struct i2c_client *client, struct rtc_time *tm)
{
struct s35390a *s35390a = i2c_get_clientdata(client);
char buf[7];
int i, err;
err = s35390a_get_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
if (err < 0)
return err;
/* This chip returns the bits of each byte in reverse order */
for (i = 0; i < 7; ++i)
buf[i] = bitrev8(buf[i]);
tm->tm_sec = bcd2bin(buf[S35390A_BYTE_SECS]);
tm->tm_min = bcd2bin(buf[S35390A_BYTE_MINS]);
tm->tm_hour = s35390a_reg2hr(s35390a, buf[S35390A_BYTE_HOURS]);
tm->tm_wday = bcd2bin(buf[S35390A_BYTE_WDAY]);
tm->tm_mday = bcd2bin(buf[S35390A_BYTE_DAY]);
tm->tm_mon = bcd2bin(buf[S35390A_BYTE_MONTH]) - 1;
tm->tm_year = bcd2bin(buf[S35390A_BYTE_YEAR]) + 100;
dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, mday=%d, "
"mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
tm->tm_wday);
return rtc_valid_tm(tm);
}
static int s35390a_set_alarm(struct i2c_client *client, struct rtc_wkalrm *alm)
{
struct s35390a *s35390a = i2c_get_clientdata(client);
char buf[3], sts = 0;
int err, i;
dev_dbg(&client->dev, "%s: alm is secs=%d, mins=%d, hours=%d mday=%d, "\
"mon=%d, year=%d, wday=%d\n", __func__, alm->time.tm_sec,
alm->time.tm_min, alm->time.tm_hour, alm->time.tm_mday,
alm->time.tm_mon, alm->time.tm_year, alm->time.tm_wday);
/* disable interrupt */
err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
if (err < 0)
return err;
/* clear pending interrupt, if any */
err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, &sts, sizeof(sts));
if (err < 0)
return err;
if (alm->enabled)
sts = S35390A_INT2_MODE_ALARM;
else
sts = S35390A_INT2_MODE_NOINTR;
/* This chip expects the bits of each byte to be in reverse order */
sts = bitrev8(sts);
/* set interupt mode*/
err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
if (err < 0)
return err;
if (alm->time.tm_wday != -1)
buf[S35390A_ALRM_BYTE_WDAY] = bin2bcd(alm->time.tm_wday) | 0x80;
else
buf[S35390A_ALRM_BYTE_WDAY] = 0;
buf[S35390A_ALRM_BYTE_HOURS] = s35390a_hr2reg(s35390a,
alm->time.tm_hour) | 0x80;
buf[S35390A_ALRM_BYTE_MINS] = bin2bcd(alm->time.tm_min) | 0x80;
if (alm->time.tm_hour >= 12)
buf[S35390A_ALRM_BYTE_HOURS] |= 0x40;
for (i = 0; i < 3; ++i)
buf[i] = bitrev8(buf[i]);
err = s35390a_set_reg(s35390a, S35390A_CMD_INT2_REG1, buf,
sizeof(buf));
return err;
}
static int s35390a_read_alarm(struct i2c_client *client, struct rtc_wkalrm *alm)
{
struct s35390a *s35390a = i2c_get_clientdata(client);
char buf[3], sts;
int i, err;
err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
if (err < 0)
return err;
if ((bitrev8(sts) & S35390A_INT2_MODE_MASK) != S35390A_INT2_MODE_ALARM) {
/*
* When the alarm isn't enabled, the register to configure
* the alarm time isn't accessible.
*/
alm->enabled = 0;
return 0;
} else {
alm->enabled = 1;
}
err = s35390a_get_reg(s35390a, S35390A_CMD_INT2_REG1, buf, sizeof(buf));
if (err < 0)
return err;
/* This chip returns the bits of each byte in reverse order */
for (i = 0; i < 3; ++i)
buf[i] = bitrev8(buf[i]);
/*
* B0 of the three matching registers is an enable flag. Iff it is set
* the configured value is used for matching.
*/
if (buf[S35390A_ALRM_BYTE_WDAY] & 0x80)
alm->time.tm_wday =
bcd2bin(buf[S35390A_ALRM_BYTE_WDAY] & ~0x80);
if (buf[S35390A_ALRM_BYTE_HOURS] & 0x80)
alm->time.tm_hour =
s35390a_reg2hr(s35390a,
buf[S35390A_ALRM_BYTE_HOURS] & ~0x80);
if (buf[S35390A_ALRM_BYTE_MINS] & 0x80)
alm->time.tm_min = bcd2bin(buf[S35390A_ALRM_BYTE_MINS] & ~0x80);
/* alarm triggers always at s=0 */
alm->time.tm_sec = 0;
dev_dbg(&client->dev, "%s: alm is mins=%d, hours=%d, wday=%d\n",
__func__, alm->time.tm_min, alm->time.tm_hour,
alm->time.tm_wday);
return 0;
}
static int s35390a_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
return s35390a_read_alarm(to_i2c_client(dev), alm);
}
static int s35390a_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
return s35390a_set_alarm(to_i2c_client(dev), alm);
}
static int s35390a_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
return s35390a_get_datetime(to_i2c_client(dev), tm);
}
static int s35390a_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
return s35390a_set_datetime(to_i2c_client(dev), tm);
}
static const struct rtc_class_ops s35390a_rtc_ops = {
.read_time = s35390a_rtc_read_time,
.set_time = s35390a_rtc_set_time,
.set_alarm = s35390a_rtc_set_alarm,
.read_alarm = s35390a_rtc_read_alarm,
};
static struct i2c_driver s35390a_driver;
static int s35390a_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
int err, err_reset;
unsigned int i;
struct s35390a *s35390a;
struct rtc_time tm;
char buf, status1;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
err = -ENODEV;
goto exit;
}
s35390a = devm_kzalloc(&client->dev, sizeof(struct s35390a),
GFP_KERNEL);
if (!s35390a) {
err = -ENOMEM;
goto exit;
}
s35390a->client[0] = client;
i2c_set_clientdata(client, s35390a);
/* This chip uses multiple addresses, use dummy devices for them */
for (i = 1; i < 8; ++i) {
s35390a->client[i] = i2c_new_dummy(client->adapter,
client->addr + i);
if (!s35390a->client[i]) {
dev_err(&client->dev, "Address %02x unavailable\n",
client->addr + i);
err = -EBUSY;
goto exit_dummy;
}
}
err_reset = s35390a_reset(s35390a, &status1);
if (err_reset < 0) {
err = err_reset;
dev_err(&client->dev, "error resetting chip\n");
goto exit_dummy;
}
if (status1 & S35390A_FLAG_24H)
s35390a->twentyfourhour = 1;
else
s35390a->twentyfourhour = 0;
if (status1 & S35390A_FLAG_INT2) {
/* disable alarm (and maybe test mode) */
buf = 0;
err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &buf, 1);
if (err < 0) {
dev_err(&client->dev, "error disabling alarm");
goto exit_dummy;
}
} else {
err = s35390a_disable_test_mode(s35390a);
if (err < 0) {
dev_err(&client->dev, "error disabling test mode\n");
goto exit_dummy;
}
}
if (err_reset > 0 || s35390a_get_datetime(client, &tm) < 0)
dev_warn(&client->dev, "clock needs to be set\n");
device_set_wakeup_capable(&client->dev, 1);
s35390a->rtc = devm_rtc_device_register(&client->dev,
s35390a_driver.driver.name,
&s35390a_rtc_ops, THIS_MODULE);
if (IS_ERR(s35390a->rtc)) {
err = PTR_ERR(s35390a->rtc);
goto exit_dummy;
}
if (status1 & S35390A_FLAG_INT2)
rtc_update_irq(s35390a->rtc, 1, RTC_AF);
return 0;
exit_dummy:
for (i = 1; i < 8; ++i)
if (s35390a->client[i])
i2c_unregister_device(s35390a->client[i]);
exit:
return err;
}
static int s35390a_remove(struct i2c_client *client)
{
unsigned int i;
struct s35390a *s35390a = i2c_get_clientdata(client);
for (i = 1; i < 8; ++i)
if (s35390a->client[i])
i2c_unregister_device(s35390a->client[i]);
return 0;
}
static struct i2c_driver s35390a_driver = {
.driver = {
.name = "rtc-s35390a",
},
.probe = s35390a_probe,
.remove = s35390a_remove,
.id_table = s35390a_id,
};
module_i2c_driver(s35390a_driver);
MODULE_AUTHOR("Byron Bradley <byron.bbradley@gmail.com>");
MODULE_DESCRIPTION("S35390A RTC driver");
MODULE_LICENSE("GPL");
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