linux/drivers/rtc/rtc-rv8803.c
Alexandre Belloni 85062c9b99 rtc: rv8803: workaround i2c HW issue
The rv8803 has a 60µs window where it will not answer on the i2c bus.
It also means there will be no ack for the communication. Make sure
communication is tried multiple times when this happens (the i2c subsystem
mandates -ENXIO is that case but the number of retries is host specific).
The critical parts are the probe function and the alarm callback so make
sure we handle the failure there.

Cc: stable@vger.kernel.org # v4.4
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
2016-03-25 02:38:59 +01:00

536 lines
13 KiB
C

/*
* RTC driver for the Micro Crystal RV8803
*
* Copyright (C) 2015 Micro Crystal SA
*
* Alexandre Belloni <alexandre.belloni@free-electrons.com>
*
* 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/bitops.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/rtc.h>
#define RV8803_SEC 0x00
#define RV8803_MIN 0x01
#define RV8803_HOUR 0x02
#define RV8803_WEEK 0x03
#define RV8803_DAY 0x04
#define RV8803_MONTH 0x05
#define RV8803_YEAR 0x06
#define RV8803_RAM 0x07
#define RV8803_ALARM_MIN 0x08
#define RV8803_ALARM_HOUR 0x09
#define RV8803_ALARM_WEEK_OR_DAY 0x0A
#define RV8803_EXT 0x0D
#define RV8803_FLAG 0x0E
#define RV8803_CTRL 0x0F
#define RV8803_EXT_WADA BIT(6)
#define RV8803_FLAG_V1F BIT(0)
#define RV8803_FLAG_V2F BIT(1)
#define RV8803_FLAG_AF BIT(3)
#define RV8803_FLAG_TF BIT(4)
#define RV8803_FLAG_UF BIT(5)
#define RV8803_CTRL_RESET BIT(0)
#define RV8803_CTRL_EIE BIT(2)
#define RV8803_CTRL_AIE BIT(3)
#define RV8803_CTRL_TIE BIT(4)
#define RV8803_CTRL_UIE BIT(5)
struct rv8803_data {
struct i2c_client *client;
struct rtc_device *rtc;
struct mutex flags_lock;
u8 ctrl;
};
static irqreturn_t rv8803_handle_irq(int irq, void *dev_id)
{
struct i2c_client *client = dev_id;
struct rv8803_data *rv8803 = i2c_get_clientdata(client);
unsigned long events = 0;
int flags, try = 0;
mutex_lock(&rv8803->flags_lock);
do {
flags = i2c_smbus_read_byte_data(client, RV8803_FLAG);
try++;
} while ((flags == -ENXIO) && (try < 3));
if (flags <= 0) {
mutex_unlock(&rv8803->flags_lock);
return IRQ_NONE;
}
if (flags & RV8803_FLAG_V1F)
dev_warn(&client->dev, "Voltage low, temperature compensation stopped.\n");
if (flags & RV8803_FLAG_V2F)
dev_warn(&client->dev, "Voltage low, data loss detected.\n");
if (flags & RV8803_FLAG_TF) {
flags &= ~RV8803_FLAG_TF;
rv8803->ctrl &= ~RV8803_CTRL_TIE;
events |= RTC_PF;
}
if (flags & RV8803_FLAG_AF) {
flags &= ~RV8803_FLAG_AF;
rv8803->ctrl &= ~RV8803_CTRL_AIE;
events |= RTC_AF;
}
if (flags & RV8803_FLAG_UF) {
flags &= ~RV8803_FLAG_UF;
rv8803->ctrl &= ~RV8803_CTRL_UIE;
events |= RTC_UF;
}
if (events) {
rtc_update_irq(rv8803->rtc, 1, events);
i2c_smbus_write_byte_data(client, RV8803_FLAG, flags);
i2c_smbus_write_byte_data(rv8803->client, RV8803_CTRL,
rv8803->ctrl);
}
mutex_unlock(&rv8803->flags_lock);
return IRQ_HANDLED;
}
static int rv8803_get_time(struct device *dev, struct rtc_time *tm)
{
struct rv8803_data *rv8803 = dev_get_drvdata(dev);
u8 date1[7];
u8 date2[7];
u8 *date = date1;
int ret, flags;
flags = i2c_smbus_read_byte_data(rv8803->client, RV8803_FLAG);
if (flags < 0)
return flags;
if (flags & RV8803_FLAG_V2F) {
dev_warn(dev, "Voltage low, data is invalid.\n");
return -EINVAL;
}
ret = i2c_smbus_read_i2c_block_data(rv8803->client, RV8803_SEC,
7, date);
if (ret != 7)
return ret < 0 ? ret : -EIO;
if ((date1[RV8803_SEC] & 0x7f) == bin2bcd(59)) {
ret = i2c_smbus_read_i2c_block_data(rv8803->client, RV8803_SEC,
7, date2);
if (ret != 7)
return ret < 0 ? ret : -EIO;
if ((date2[RV8803_SEC] & 0x7f) != bin2bcd(59))
date = date2;
}
tm->tm_sec = bcd2bin(date[RV8803_SEC] & 0x7f);
tm->tm_min = bcd2bin(date[RV8803_MIN] & 0x7f);
tm->tm_hour = bcd2bin(date[RV8803_HOUR] & 0x3f);
tm->tm_wday = ffs(date[RV8803_WEEK] & 0x7f);
tm->tm_mday = bcd2bin(date[RV8803_DAY] & 0x3f);
tm->tm_mon = bcd2bin(date[RV8803_MONTH] & 0x1f) - 1;
tm->tm_year = bcd2bin(date[RV8803_YEAR]) + 100;
return rtc_valid_tm(tm);
}
static int rv8803_set_time(struct device *dev, struct rtc_time *tm)
{
struct rv8803_data *rv8803 = dev_get_drvdata(dev);
u8 date[7];
int flags, ret;
if ((tm->tm_year < 100) || (tm->tm_year > 199))
return -EINVAL;
date[RV8803_SEC] = bin2bcd(tm->tm_sec);
date[RV8803_MIN] = bin2bcd(tm->tm_min);
date[RV8803_HOUR] = bin2bcd(tm->tm_hour);
date[RV8803_WEEK] = 1 << (tm->tm_wday);
date[RV8803_DAY] = bin2bcd(tm->tm_mday);
date[RV8803_MONTH] = bin2bcd(tm->tm_mon + 1);
date[RV8803_YEAR] = bin2bcd(tm->tm_year - 100);
ret = i2c_smbus_write_i2c_block_data(rv8803->client, RV8803_SEC,
7, date);
if (ret < 0)
return ret;
mutex_lock(&rv8803->flags_lock);
flags = i2c_smbus_read_byte_data(rv8803->client, RV8803_FLAG);
if (flags < 0) {
mutex_unlock(&rv8803->flags_lock);
return flags;
}
ret = i2c_smbus_write_byte_data(rv8803->client, RV8803_FLAG,
flags & ~RV8803_FLAG_V2F);
mutex_unlock(&rv8803->flags_lock);
return ret;
}
static int rv8803_get_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct rv8803_data *rv8803 = dev_get_drvdata(dev);
struct i2c_client *client = rv8803->client;
u8 alarmvals[3];
int flags, ret;
ret = i2c_smbus_read_i2c_block_data(client, RV8803_ALARM_MIN,
3, alarmvals);
if (ret != 3)
return ret < 0 ? ret : -EIO;
flags = i2c_smbus_read_byte_data(client, RV8803_FLAG);
if (flags < 0)
return flags;
alrm->time.tm_sec = 0;
alrm->time.tm_min = bcd2bin(alarmvals[0] & 0x7f);
alrm->time.tm_hour = bcd2bin(alarmvals[1] & 0x3f);
alrm->time.tm_wday = -1;
alrm->time.tm_mday = bcd2bin(alarmvals[2] & 0x3f);
alrm->time.tm_mon = -1;
alrm->time.tm_year = -1;
alrm->enabled = !!(rv8803->ctrl & RV8803_CTRL_AIE);
alrm->pending = (flags & RV8803_FLAG_AF) && alrm->enabled;
return 0;
}
static int rv8803_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct i2c_client *client = to_i2c_client(dev);
struct rv8803_data *rv8803 = dev_get_drvdata(dev);
u8 alarmvals[3];
u8 ctrl[2];
int ret, err;
/* The alarm has no seconds, round up to nearest minute */
if (alrm->time.tm_sec) {
time64_t alarm_time = rtc_tm_to_time64(&alrm->time);
alarm_time += 60 - alrm->time.tm_sec;
rtc_time64_to_tm(alarm_time, &alrm->time);
}
mutex_lock(&rv8803->flags_lock);
ret = i2c_smbus_read_i2c_block_data(client, RV8803_FLAG, 2, ctrl);
if (ret != 2) {
mutex_unlock(&rv8803->flags_lock);
return ret < 0 ? ret : -EIO;
}
alarmvals[0] = bin2bcd(alrm->time.tm_min);
alarmvals[1] = bin2bcd(alrm->time.tm_hour);
alarmvals[2] = bin2bcd(alrm->time.tm_mday);
if (rv8803->ctrl & (RV8803_CTRL_AIE | RV8803_CTRL_UIE)) {
rv8803->ctrl &= ~(RV8803_CTRL_AIE | RV8803_CTRL_UIE);
err = i2c_smbus_write_byte_data(rv8803->client, RV8803_CTRL,
rv8803->ctrl);
if (err) {
mutex_unlock(&rv8803->flags_lock);
return err;
}
}
ctrl[1] &= ~RV8803_FLAG_AF;
err = i2c_smbus_write_byte_data(rv8803->client, RV8803_FLAG, ctrl[1]);
mutex_unlock(&rv8803->flags_lock);
if (err)
return err;
err = i2c_smbus_write_i2c_block_data(rv8803->client, RV8803_ALARM_MIN,
3, alarmvals);
if (err)
return err;
if (alrm->enabled) {
if (rv8803->rtc->uie_rtctimer.enabled)
rv8803->ctrl |= RV8803_CTRL_UIE;
if (rv8803->rtc->aie_timer.enabled)
rv8803->ctrl |= RV8803_CTRL_AIE;
err = i2c_smbus_write_byte_data(rv8803->client, RV8803_CTRL,
rv8803->ctrl);
if (err)
return err;
}
return 0;
}
static int rv8803_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct i2c_client *client = to_i2c_client(dev);
struct rv8803_data *rv8803 = dev_get_drvdata(dev);
int ctrl, flags, err;
ctrl = rv8803->ctrl;
if (enabled) {
if (rv8803->rtc->uie_rtctimer.enabled)
ctrl |= RV8803_CTRL_UIE;
if (rv8803->rtc->aie_timer.enabled)
ctrl |= RV8803_CTRL_AIE;
} else {
if (!rv8803->rtc->uie_rtctimer.enabled)
ctrl &= ~RV8803_CTRL_UIE;
if (!rv8803->rtc->aie_timer.enabled)
ctrl &= ~RV8803_CTRL_AIE;
}
mutex_lock(&rv8803->flags_lock);
flags = i2c_smbus_read_byte_data(client, RV8803_FLAG);
if (flags < 0) {
mutex_unlock(&rv8803->flags_lock);
return flags;
}
flags &= ~(RV8803_FLAG_AF | RV8803_FLAG_UF);
err = i2c_smbus_write_byte_data(client, RV8803_FLAG, flags);
mutex_unlock(&rv8803->flags_lock);
if (err)
return err;
if (ctrl != rv8803->ctrl) {
rv8803->ctrl = ctrl;
err = i2c_smbus_write_byte_data(client, RV8803_CTRL,
rv8803->ctrl);
if (err)
return err;
}
return 0;
}
static int rv8803_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
{
struct i2c_client *client = to_i2c_client(dev);
struct rv8803_data *rv8803 = dev_get_drvdata(dev);
int flags, ret = 0;
switch (cmd) {
case RTC_VL_READ:
flags = i2c_smbus_read_byte_data(client, RV8803_FLAG);
if (flags < 0)
return flags;
if (flags & RV8803_FLAG_V1F)
dev_warn(&client->dev, "Voltage low, temperature compensation stopped.\n");
if (flags & RV8803_FLAG_V2F)
dev_warn(&client->dev, "Voltage low, data loss detected.\n");
flags &= RV8803_FLAG_V1F | RV8803_FLAG_V2F;
if (copy_to_user((void __user *)arg, &flags, sizeof(int)))
return -EFAULT;
return 0;
case RTC_VL_CLR:
mutex_lock(&rv8803->flags_lock);
flags = i2c_smbus_read_byte_data(client, RV8803_FLAG);
if (flags < 0) {
mutex_unlock(&rv8803->flags_lock);
return flags;
}
flags &= ~(RV8803_FLAG_V1F | RV8803_FLAG_V2F);
ret = i2c_smbus_write_byte_data(client, RV8803_FLAG, flags);
mutex_unlock(&rv8803->flags_lock);
if (ret < 0)
return ret;
return 0;
default:
return -ENOIOCTLCMD;
}
}
static ssize_t rv8803_nvram_write(struct file *filp, struct kobject *kobj,
struct bin_attribute *attr,
char *buf, loff_t off, size_t count)
{
struct device *dev = kobj_to_dev(kobj);
struct i2c_client *client = to_i2c_client(dev);
int ret;
ret = i2c_smbus_write_byte_data(client, RV8803_RAM, buf[0]);
if (ret < 0)
return ret;
return 1;
}
static ssize_t rv8803_nvram_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *attr,
char *buf, loff_t off, size_t count)
{
struct device *dev = kobj_to_dev(kobj);
struct i2c_client *client = to_i2c_client(dev);
int ret;
ret = i2c_smbus_read_byte_data(client, RV8803_RAM);
if (ret < 0)
return ret;
buf[0] = ret;
return 1;
}
static struct bin_attribute rv8803_nvram_attr = {
.attr = {
.name = "nvram",
.mode = S_IRUGO | S_IWUSR,
},
.size = 1,
.read = rv8803_nvram_read,
.write = rv8803_nvram_write,
};
static struct rtc_class_ops rv8803_rtc_ops = {
.read_time = rv8803_get_time,
.set_time = rv8803_set_time,
.ioctl = rv8803_ioctl,
};
static int rv8803_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
struct rv8803_data *rv8803;
int err, flags, try = 0;
if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
I2C_FUNC_SMBUS_I2C_BLOCK)) {
dev_err(&adapter->dev, "doesn't support I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_I2C_BLOCK\n");
return -EIO;
}
rv8803 = devm_kzalloc(&client->dev, sizeof(struct rv8803_data),
GFP_KERNEL);
if (!rv8803)
return -ENOMEM;
mutex_init(&rv8803->flags_lock);
rv8803->client = client;
i2c_set_clientdata(client, rv8803);
/*
* There is a 60µs window where the RTC may not reply on the i2c bus in
* that case, the transfer is not ACKed. In that case, ensure there are
* multiple attempts.
*/
do {
flags = i2c_smbus_read_byte_data(client, RV8803_FLAG);
try++;
} while ((flags == -ENXIO) && (try < 3));
if (flags < 0)
return flags;
if (flags & RV8803_FLAG_V1F)
dev_warn(&client->dev, "Voltage low, temperature compensation stopped.\n");
if (flags & RV8803_FLAG_V2F)
dev_warn(&client->dev, "Voltage low, data loss detected.\n");
if (flags & RV8803_FLAG_AF)
dev_warn(&client->dev, "An alarm maybe have been missed.\n");
if (client->irq > 0) {
err = devm_request_threaded_irq(&client->dev, client->irq,
NULL, rv8803_handle_irq,
IRQF_TRIGGER_LOW | IRQF_ONESHOT,
"rv8803", client);
if (err) {
dev_warn(&client->dev, "unable to request IRQ, alarms disabled\n");
client->irq = 0;
} else {
rv8803_rtc_ops.read_alarm = rv8803_get_alarm;
rv8803_rtc_ops.set_alarm = rv8803_set_alarm;
rv8803_rtc_ops.alarm_irq_enable = rv8803_alarm_irq_enable;
}
}
rv8803->rtc = devm_rtc_device_register(&client->dev, client->name,
&rv8803_rtc_ops, THIS_MODULE);
if (IS_ERR(rv8803->rtc)) {
dev_err(&client->dev, "unable to register the class device\n");
return PTR_ERR(rv8803->rtc);
}
try = 0;
do {
err = i2c_smbus_write_byte_data(rv8803->client, RV8803_EXT,
RV8803_EXT_WADA);
try++;
} while ((err == -ENXIO) && (try < 3));
if (err)
return err;
err = device_create_bin_file(&client->dev, &rv8803_nvram_attr);
if (err)
return err;
rv8803->rtc->max_user_freq = 1;
return 0;
}
static int rv8803_remove(struct i2c_client *client)
{
device_remove_bin_file(&client->dev, &rv8803_nvram_attr);
return 0;
}
static const struct i2c_device_id rv8803_id[] = {
{ "rv8803", 0 },
{ "rx8900", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, rv8803_id);
static struct i2c_driver rv8803_driver = {
.driver = {
.name = "rtc-rv8803",
},
.probe = rv8803_probe,
.remove = rv8803_remove,
.id_table = rv8803_id,
};
module_i2c_driver(rv8803_driver);
MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>");
MODULE_DESCRIPTION("Micro Crystal RV8803 RTC driver");
MODULE_LICENSE("GPL v2");