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alistair23-linux/drivers/rtc/rtc-rv8803.c
Benoît Thébaudeau 6f367788d6 rtc: rv8803: Clear V1F when setting the time 
V1F indicates that the time accuracy may have been compromised because
of a voltage drop (possibly only temporary) below VLOW1, which stops the
temperature compensation. When the time is set, the accuracy is
restored, so V1F should be cleared in order to indicate this and to be
able to detect the next temperature compensation loss. This is the same
principle as for V2F, which is cleared when the time is set to indicate
that the time is no longer invalid and to be able to detect the next
data loss.

Signed-off-by: Benoît Thébaudeau <benoit@wsystem.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
2016-07-28 09:59:43 +02:00

597 lines
14 KiB
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/*
* 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/log2.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/rtc.h>
#define RV8803_I2C_TRY_COUNT 4
#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 int rv8803_read_reg(const struct i2c_client *client, u8 reg)
{
int try = RV8803_I2C_TRY_COUNT;
s32 ret;
/*
* There is a 61µs window during which the RTC does not acknowledge I2C
* transfers. In that case, ensure that there are multiple attempts.
*/
do
ret = i2c_smbus_read_byte_data(client, reg);
while ((ret == -ENXIO || ret == -EIO) && --try);
if (ret < 0)
dev_err(&client->dev, "Unable to read register 0x%02x\n", reg);
return ret;
}
static int rv8803_read_regs(const struct i2c_client *client,
u8 reg, u8 count, u8 *values)
{
int try = RV8803_I2C_TRY_COUNT;
s32 ret;
do
ret = i2c_smbus_read_i2c_block_data(client, reg, count, values);
while ((ret == -ENXIO || ret == -EIO) && --try);
if (ret != count) {
dev_err(&client->dev,
"Unable to read registers 0x%02x..0x%02x\n",
reg, reg + count - 1);
return ret < 0 ? ret : -EIO;
}
return 0;
}
static int rv8803_write_reg(const struct i2c_client *client, u8 reg, u8 value)
{
int try = RV8803_I2C_TRY_COUNT;
s32 ret;
do
ret = i2c_smbus_write_byte_data(client, reg, value);
while ((ret == -ENXIO || ret == -EIO) && --try);
if (ret)
dev_err(&client->dev, "Unable to write register 0x%02x\n", reg);
return ret;
}
static int rv8803_write_regs(const struct i2c_client *client,
u8 reg, u8 count, const u8 *values)
{
int try = RV8803_I2C_TRY_COUNT;
s32 ret;
do
ret = i2c_smbus_write_i2c_block_data(client, reg, count,
values);
while ((ret == -ENXIO || ret == -EIO) && --try);
if (ret)
dev_err(&client->dev,
"Unable to write registers 0x%02x..0x%02x\n",
reg, reg + count - 1);
return ret;
}
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;
mutex_lock(&rv8803->flags_lock);
flags = rv8803_read_reg(client, RV8803_FLAG);
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);
rv8803_write_reg(client, RV8803_FLAG, flags);
rv8803_write_reg(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 = rv8803_read_reg(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 = rv8803_read_regs(rv8803->client, RV8803_SEC, 7, date);
if (ret)
return ret;
if ((date1[RV8803_SEC] & 0x7f) == bin2bcd(59)) {
ret = rv8803_read_regs(rv8803->client, RV8803_SEC, 7, date2);
if (ret)
return ret;
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 = ilog2(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 0;
}
static int rv8803_set_time(struct device *dev, struct rtc_time *tm)
{
struct rv8803_data *rv8803 = dev_get_drvdata(dev);
u8 date[7];
int ctrl, flags, ret;
if ((tm->tm_year < 100) || (tm->tm_year > 199))
return -EINVAL;
ctrl = rv8803_read_reg(rv8803->client, RV8803_CTRL);
if (ctrl < 0)
return ctrl;
/* Stop the clock */
ret = rv8803_write_reg(rv8803->client, RV8803_CTRL,
ctrl | RV8803_CTRL_RESET);
if (ret)
return ret;
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 = rv8803_write_regs(rv8803->client, RV8803_SEC, 7, date);
if (ret)
return ret;
/* Restart the clock */
ret = rv8803_write_reg(rv8803->client, RV8803_CTRL,
ctrl & ~RV8803_CTRL_RESET);
if (ret)
return ret;
mutex_lock(&rv8803->flags_lock);
flags = rv8803_read_reg(rv8803->client, RV8803_FLAG);
if (flags < 0) {
mutex_unlock(&rv8803->flags_lock);
return flags;
}
ret = rv8803_write_reg(rv8803->client, RV8803_FLAG,
flags & ~(RV8803_FLAG_V1F | 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 = rv8803_read_regs(client, RV8803_ALARM_MIN, 3, alarmvals);
if (ret)
return ret;
flags = rv8803_read_reg(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_mday = bcd2bin(alarmvals[2] & 0x3f);
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 = rv8803_read_regs(client, RV8803_FLAG, 2, ctrl);
if (ret) {
mutex_unlock(&rv8803->flags_lock);
return ret;
}
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 = rv8803_write_reg(rv8803->client, RV8803_CTRL,
rv8803->ctrl);
if (err) {
mutex_unlock(&rv8803->flags_lock);
return err;
}
}
ctrl[1] &= ~RV8803_FLAG_AF;
err = rv8803_write_reg(rv8803->client, RV8803_FLAG, ctrl[1]);
mutex_unlock(&rv8803->flags_lock);
if (err)
return err;
err = rv8803_write_regs(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 = rv8803_write_reg(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 = rv8803_read_reg(client, RV8803_FLAG);
if (flags < 0) {
mutex_unlock(&rv8803->flags_lock);
return flags;
}
flags &= ~(RV8803_FLAG_AF | RV8803_FLAG_UF);
err = rv8803_write_reg(client, RV8803_FLAG, flags);
mutex_unlock(&rv8803->flags_lock);
if (err)
return err;
if (ctrl != rv8803->ctrl) {
rv8803->ctrl = ctrl;
err = rv8803_write_reg(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 = rv8803_read_reg(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 = rv8803_read_reg(client, RV8803_FLAG);
if (flags < 0) {
mutex_unlock(&rv8803->flags_lock);
return flags;
}
flags &= ~(RV8803_FLAG_V1F | RV8803_FLAG_V2F);
ret = rv8803_write_reg(client, RV8803_FLAG, flags);
mutex_unlock(&rv8803->flags_lock);
if (ret)
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 = rv8803_write_reg(client, RV8803_RAM, buf[0]);
if (ret)
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 = rv8803_read_reg(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;
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);
flags = rv8803_read_reg(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");
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);
}
err = rv8803_write_reg(rv8803->client, RV8803_EXT, RV8803_EXT_WADA);
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");
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