linux/drivers/rtc/rtc-cros-ec.c
Jeffy Chen 72dd71f0da rtc: cros-ec: return -ETIME when refused to set alarms in the past
Since accessing a Chrome OS EC based rtc is a slow operation, there is a
race window where if the alarm is set for the next second and the second
ticks over right before calculating the alarm offset.

In this case the current driver is setting a 0-second alarm, which would
be considered as disabling alarms by the EC(EC_RTC_ALARM_CLEAR).

This breaks, e.g., hwclock which relies on RTC_UIE_ON ->
rtc_update_irq_enable(), which sets a 1-second alarm and expects it to
fire an interrupt.

So return -ETIME when the alarm is in the past, follow __rtc_set_alarm().

Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Tested-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2018-03-17 14:20:53 +01:00

414 lines
10 KiB
C

/*
* RTC driver for Chrome OS Embedded Controller
*
* Copyright (c) 2017, Google, Inc
*
* Author: Stephen Barber <smbarber@chromium.org>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*/
#include <linux/kernel.h>
#include <linux/mfd/cros_ec.h>
#include <linux/mfd/cros_ec_commands.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/slab.h>
#define DRV_NAME "cros-ec-rtc"
/**
* struct cros_ec_rtc - Driver data for EC RTC
*
* @cros_ec: Pointer to EC device
* @rtc: Pointer to RTC device
* @notifier: Notifier info for responding to EC events
* @saved_alarm: Alarm to restore when interrupts are reenabled
*/
struct cros_ec_rtc {
struct cros_ec_device *cros_ec;
struct rtc_device *rtc;
struct notifier_block notifier;
u32 saved_alarm;
};
static int cros_ec_rtc_get(struct cros_ec_device *cros_ec, u32 command,
u32 *response)
{
int ret;
struct {
struct cros_ec_command msg;
struct ec_response_rtc data;
} __packed msg;
memset(&msg, 0, sizeof(msg));
msg.msg.command = command;
msg.msg.insize = sizeof(msg.data);
ret = cros_ec_cmd_xfer_status(cros_ec, &msg.msg);
if (ret < 0) {
dev_err(cros_ec->dev,
"error getting %s from EC: %d\n",
command == EC_CMD_RTC_GET_VALUE ? "time" : "alarm",
ret);
return ret;
}
*response = msg.data.time;
return 0;
}
static int cros_ec_rtc_set(struct cros_ec_device *cros_ec, u32 command,
u32 param)
{
int ret = 0;
struct {
struct cros_ec_command msg;
struct ec_response_rtc data;
} __packed msg;
memset(&msg, 0, sizeof(msg));
msg.msg.command = command;
msg.msg.outsize = sizeof(msg.data);
msg.data.time = param;
ret = cros_ec_cmd_xfer_status(cros_ec, &msg.msg);
if (ret < 0) {
dev_err(cros_ec->dev, "error setting %s on EC: %d\n",
command == EC_CMD_RTC_SET_VALUE ? "time" : "alarm",
ret);
return ret;
}
return 0;
}
/* Read the current time from the EC. */
static int cros_ec_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
int ret;
u32 time;
ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &time);
if (ret) {
dev_err(dev, "error getting time: %d\n", ret);
return ret;
}
rtc_time64_to_tm(time, tm);
return 0;
}
/* Set the current EC time. */
static int cros_ec_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
int ret;
time64_t time;
time = rtc_tm_to_time64(tm);
if (time < 0 || time > U32_MAX)
return -EINVAL;
ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_VALUE, (u32)time);
if (ret < 0) {
dev_err(dev, "error setting time: %d\n", ret);
return ret;
}
return 0;
}
/* Read alarm time from RTC. */
static int cros_ec_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
int ret;
u32 current_time, alarm_offset;
/*
* The EC host command for getting the alarm is relative (i.e. 5
* seconds from now) whereas rtc_wkalrm is absolute. Get the current
* RTC time first so we can calculate the relative time.
*/
ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
if (ret < 0) {
dev_err(dev, "error getting time: %d\n", ret);
return ret;
}
ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_ALARM, &alarm_offset);
if (ret < 0) {
dev_err(dev, "error getting alarm: %d\n", ret);
return ret;
}
rtc_time64_to_tm(current_time + alarm_offset, &alrm->time);
return 0;
}
/* Set the EC's RTC alarm. */
static int cros_ec_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
int ret;
time64_t alarm_time;
u32 current_time, alarm_offset;
/*
* The EC host command for setting the alarm is relative
* (i.e. 5 seconds from now) whereas rtc_wkalrm is absolute.
* Get the current RTC time first so we can calculate the
* relative time.
*/
ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
if (ret < 0) {
dev_err(dev, "error getting time: %d\n", ret);
return ret;
}
alarm_time = rtc_tm_to_time64(&alrm->time);
if (alarm_time < 0 || alarm_time > U32_MAX)
return -EINVAL;
if (!alrm->enabled) {
/*
* If the alarm is being disabled, send an alarm
* clear command.
*/
alarm_offset = EC_RTC_ALARM_CLEAR;
cros_ec_rtc->saved_alarm = (u32)alarm_time;
} else {
/* Don't set an alarm in the past. */
if ((u32)alarm_time <= current_time)
return -ETIME;
alarm_offset = (u32)alarm_time - current_time;
}
ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM, alarm_offset);
if (ret < 0) {
dev_err(dev, "error setting alarm: %d\n", ret);
return ret;
}
return 0;
}
static int cros_ec_rtc_alarm_irq_enable(struct device *dev,
unsigned int enabled)
{
struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
int ret;
u32 current_time, alarm_offset, alarm_value;
ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
if (ret < 0) {
dev_err(dev, "error getting time: %d\n", ret);
return ret;
}
if (enabled) {
/* Restore saved alarm if it's still in the future. */
if (cros_ec_rtc->saved_alarm < current_time)
alarm_offset = EC_RTC_ALARM_CLEAR;
else
alarm_offset = cros_ec_rtc->saved_alarm - current_time;
ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,
alarm_offset);
if (ret < 0) {
dev_err(dev, "error restoring alarm: %d\n", ret);
return ret;
}
} else {
/* Disable alarm, saving the old alarm value. */
ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_ALARM,
&alarm_offset);
if (ret < 0) {
dev_err(dev, "error saving alarm: %d\n", ret);
return ret;
}
alarm_value = current_time + alarm_offset;
/*
* If the current EC alarm is already past, we don't want
* to set an alarm when we go through the alarm irq enable
* path.
*/
if (alarm_value < current_time)
cros_ec_rtc->saved_alarm = EC_RTC_ALARM_CLEAR;
else
cros_ec_rtc->saved_alarm = alarm_value;
alarm_offset = EC_RTC_ALARM_CLEAR;
ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,
alarm_offset);
if (ret < 0) {
dev_err(dev, "error disabling alarm: %d\n", ret);
return ret;
}
}
return 0;
}
static int cros_ec_rtc_event(struct notifier_block *nb,
unsigned long queued_during_suspend,
void *_notify)
{
struct cros_ec_rtc *cros_ec_rtc;
struct rtc_device *rtc;
struct cros_ec_device *cros_ec;
u32 host_event;
cros_ec_rtc = container_of(nb, struct cros_ec_rtc, notifier);
rtc = cros_ec_rtc->rtc;
cros_ec = cros_ec_rtc->cros_ec;
host_event = cros_ec_get_host_event(cros_ec);
if (host_event & EC_HOST_EVENT_MASK(EC_HOST_EVENT_RTC)) {
rtc_update_irq(rtc, 1, RTC_IRQF | RTC_AF);
return NOTIFY_OK;
} else {
return NOTIFY_DONE;
}
}
static const struct rtc_class_ops cros_ec_rtc_ops = {
.read_time = cros_ec_rtc_read_time,
.set_time = cros_ec_rtc_set_time,
.read_alarm = cros_ec_rtc_read_alarm,
.set_alarm = cros_ec_rtc_set_alarm,
.alarm_irq_enable = cros_ec_rtc_alarm_irq_enable,
};
#ifdef CONFIG_PM_SLEEP
static int cros_ec_rtc_suspend(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(&pdev->dev);
if (device_may_wakeup(dev))
enable_irq_wake(cros_ec_rtc->cros_ec->irq);
return 0;
}
static int cros_ec_rtc_resume(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(&pdev->dev);
if (device_may_wakeup(dev))
disable_irq_wake(cros_ec_rtc->cros_ec->irq);
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(cros_ec_rtc_pm_ops, cros_ec_rtc_suspend,
cros_ec_rtc_resume);
static int cros_ec_rtc_probe(struct platform_device *pdev)
{
struct cros_ec_dev *ec_dev = dev_get_drvdata(pdev->dev.parent);
struct cros_ec_device *cros_ec = ec_dev->ec_dev;
struct cros_ec_rtc *cros_ec_rtc;
struct rtc_time tm;
int ret;
cros_ec_rtc = devm_kzalloc(&pdev->dev, sizeof(*cros_ec_rtc),
GFP_KERNEL);
if (!cros_ec_rtc)
return -ENOMEM;
platform_set_drvdata(pdev, cros_ec_rtc);
cros_ec_rtc->cros_ec = cros_ec;
/* Get initial time */
ret = cros_ec_rtc_read_time(&pdev->dev, &tm);
if (ret) {
dev_err(&pdev->dev, "failed to read RTC time\n");
return ret;
}
ret = device_init_wakeup(&pdev->dev, 1);
if (ret) {
dev_err(&pdev->dev, "failed to initialize wakeup\n");
return ret;
}
cros_ec_rtc->rtc = devm_rtc_device_register(&pdev->dev, DRV_NAME,
&cros_ec_rtc_ops,
THIS_MODULE);
if (IS_ERR(cros_ec_rtc->rtc)) {
ret = PTR_ERR(cros_ec_rtc->rtc);
dev_err(&pdev->dev, "failed to register rtc device\n");
return ret;
}
/* Get RTC events from the EC. */
cros_ec_rtc->notifier.notifier_call = cros_ec_rtc_event;
ret = blocking_notifier_chain_register(&cros_ec->event_notifier,
&cros_ec_rtc->notifier);
if (ret) {
dev_err(&pdev->dev, "failed to register notifier\n");
return ret;
}
return 0;
}
static int cros_ec_rtc_remove(struct platform_device *pdev)
{
struct cros_ec_rtc *cros_ec_rtc = platform_get_drvdata(pdev);
struct device *dev = &pdev->dev;
int ret;
ret = blocking_notifier_chain_unregister(
&cros_ec_rtc->cros_ec->event_notifier,
&cros_ec_rtc->notifier);
if (ret) {
dev_err(dev, "failed to unregister notifier\n");
return ret;
}
return 0;
}
static struct platform_driver cros_ec_rtc_driver = {
.probe = cros_ec_rtc_probe,
.remove = cros_ec_rtc_remove,
.driver = {
.name = DRV_NAME,
.pm = &cros_ec_rtc_pm_ops,
},
};
module_platform_driver(cros_ec_rtc_driver);
MODULE_DESCRIPTION("RTC driver for Chrome OS ECs");
MODULE_AUTHOR("Stephen Barber <smbarber@chromium.org>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRV_NAME);