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    Subject[PATCH 6/7] rtc: cros-ec: add cros-ec-rtc driver.
    Date
    From: Stephen Barber <smbarber@chromium.org>

    On platforms with a Chrome OS EC, the EC can function as a simple RTC.
    Add a basic driver with this functionality.

    Signed-off-by: Stephen Barber <smbarber@chromium.org>
    Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
    Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
    ---
    drivers/rtc/Kconfig | 10 ++
    drivers/rtc/Makefile | 1 +
    drivers/rtc/rtc-cros-ec.c | 412 ++++++++++++++++++++++++++++++++++++++++++++++
    3 files changed, 423 insertions(+)
    create mode 100644 drivers/rtc/rtc-cros-ec.c

    diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
    index 050bec7..b2939b4 100644
    --- a/drivers/rtc/Kconfig
    +++ b/drivers/rtc/Kconfig
    @@ -1204,6 +1204,16 @@ config RTC_DRV_ZYNQMP
    If you say yes here you get support for the RTC controller found on
    Xilinx Zynq Ultrascale+ MPSoC.

    +config RTC_DRV_CROS_EC
    + tristate "Chrome OS EC RTC driver"
    + depends on MFD_CROS_EC
    + help
    + If you say yes here you will get support for the
    + Chrome OS Embedded Controller's RTC.
    +
    + This driver can also be built as a module. If so, the module
    + will be called rtc-cros-ec.
    +
    comment "on-CPU RTC drivers"

    config RTC_DRV_ASM9260
    diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
    index 13857d2..8162983 100644
    --- a/drivers/rtc/Makefile
    +++ b/drivers/rtc/Makefile
    @@ -41,6 +41,7 @@ obj-$(CONFIG_RTC_DRV_BQ4802) += rtc-bq4802.o
    obj-$(CONFIG_RTC_DRV_CMOS) += rtc-cmos.o
    obj-$(CONFIG_RTC_DRV_COH901331) += rtc-coh901331.o
    obj-$(CONFIG_RTC_DRV_CPCAP) += rtc-cpcap.o
    +obj-$(CONFIG_RTC_DRV_CROS_EC) += rtc-cros-ec.o
    obj-$(CONFIG_RTC_DRV_DA9052) += rtc-da9052.o
    obj-$(CONFIG_RTC_DRV_DA9055) += rtc-da9055.o
    obj-$(CONFIG_RTC_DRV_DA9063) += rtc-da9063.o
    diff --git a/drivers/rtc/rtc-cros-ec.c b/drivers/rtc/rtc-cros-ec.c
    new file mode 100644
    index 0000000..a5c2512
    --- /dev/null
    +++ b/drivers/rtc/rtc-cros-ec.c
    @@ -0,0 +1,412 @@
    +/*
    + * 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)
    + alarm_offset = EC_RTC_ALARM_CLEAR;
    + else
    + 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_device *cros_ec_dev = dev_get_drvdata(pdev->dev.parent);
    + 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_dev;
    +
    + /* 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_dev->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);
    --
    2.9.3
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      Last update: 2017-03-24 18:45    [W:4.348 / U:0.352 seconds]
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