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    Subject[PATCH 11/11] misc/throttler: Add Chrome OS EC throttler
    Date
    The driver subscribes to throttling events from the Chrome OS
    embedded controller and enables/disables system throttling based
    on these events.

    Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
    ---
    drivers/misc/throttler/Kconfig | 15 +++
    drivers/misc/throttler/Makefile | 1 +
    drivers/misc/throttler/cros_ec_throttler.c | 122 +++++++++++++++++++++
    3 files changed, 138 insertions(+)
    create mode 100644 drivers/misc/throttler/cros_ec_throttler.c

    diff --git a/drivers/misc/throttler/Kconfig b/drivers/misc/throttler/Kconfig
    index ef8388f6bc0a..652b6817b75c 100644
    --- a/drivers/misc/throttler/Kconfig
    +++ b/drivers/misc/throttler/Kconfig
    @@ -11,3 +11,18 @@ menuconfig THROTTLER
    Note that you also need a event monitor module usually called
    *_throttler.

    +if THROTTLER
    +
    +config CROS_EC_THROTTLER
    + tristate "Throttler event monitor for the Chrome OS Embedded Controller"
    + default n
    + depends on MFD_CROS_EC
    + ---help---
    + This driver adds support to throttle the system in reaction to
    + Chrome OS EC events.
    +
    + To compile this driver as a module, choose M here: the
    + module will be called cros_ec_throttler.
    +
    +endif # THROTTLER
    +
    diff --git a/drivers/misc/throttler/Makefile b/drivers/misc/throttler/Makefile
    index c8d920cee315..d9b2a77dabc9 100644
    --- a/drivers/misc/throttler/Makefile
    +++ b/drivers/misc/throttler/Makefile
    @@ -1 +1,2 @@
    obj-$(CONFIG_THROTTLER) += core.o
    +obj-$(CONFIG_CROS_EC_THROTTLER) += cros_ec_throttler.o
    diff --git a/drivers/misc/throttler/cros_ec_throttler.c b/drivers/misc/throttler/cros_ec_throttler.c
    new file mode 100644
    index 000000000000..ea6bc002d49c
    --- /dev/null
    +++ b/drivers/misc/throttler/cros_ec_throttler.c
    @@ -0,0 +1,122 @@
    +/*
    + * Driver for throttling triggered by EC events.
    + *
    + * Copyright (C) 2018 Google, Inc.
    + *
    + * This software is licensed under the terms of the GNU General Public
    + * License version 2, as published by the Free Software Foundation, and
    + * may be copied, distributed, and modified under those terms.
    + *
    + * This program is distributed in the hope that 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/module.h>
    +#include <linux/notifier.h>
    +#include <linux/of.h>
    +#include <linux/of_platform.h>
    +#include <linux/platform_device.h>
    +#include <linux/throttler.h>
    +
    +struct cros_ec_throttler {
    + struct cros_ec_device *ec;
    + struct throttler *throttler;
    + struct notifier_block nb;
    +};
    +
    +static int cros_ec_throttler_event(struct notifier_block *nb,
    + unsigned long queued_during_suspend, void *_notify)
    +{
    + struct cros_ec_throttler *cte =
    + container_of(nb, struct cros_ec_throttler, nb);
    + u32 host_event;
    +
    + host_event = cros_ec_get_host_event(cte->ec);
    + if (host_event & EC_HOST_EVENT_MASK(EC_HOST_EVENT_THROTTLE_START)) {
    + throttler_set_level(cte->throttler, 1);
    +
    + return NOTIFY_OK;
    + } else if (host_event & EC_HOST_EVENT_MASK(EC_HOST_EVENT_THROTTLE_STOP)) {
    + throttler_set_level(cte->throttler, 0);
    +
    + return NOTIFY_OK;
    + }
    +
    + return NOTIFY_DONE;
    +}
    +
    +static int cros_ec_throttler_probe(struct platform_device *pdev)
    +{
    + struct cros_ec_throttler *cte;
    + struct device *dev = &pdev->dev;
    + struct device_node *np = pdev->dev.of_node;
    + int ret;
    +
    + if (!np) {
    + /* should never happen */
    + return -EINVAL;
    + }
    +
    + cte = devm_kzalloc(dev, sizeof(*cte), GFP_KERNEL);
    + if (!cte)
    + return -ENOMEM;
    +
    + cte->ec = dev_get_drvdata(pdev->dev.parent);
    +
    + cte->throttler = throttler_setup(dev);
    + if (IS_ERR(cte->throttler))
    + return PTR_ERR(cte->throttler);
    +
    + dev_set_drvdata(dev, cte);
    +
    + cte->nb.notifier_call = cros_ec_throttler_event;
    + ret = blocking_notifier_chain_register(&cte->ec->event_notifier,
    + &cte->nb);
    + if (ret < 0) {
    + dev_err(dev, "failed to register notifier\n");
    + throttler_teardown(cte->throttler);
    + return ret;
    + }
    +
    + return 0;
    +}
    +
    +static int cros_ec_throttler_remove(struct platform_device *pdev)
    +{
    + struct cros_ec_throttler *cte = platform_get_drvdata(pdev);
    +
    + blocking_notifier_chain_unregister(&cte->ec->event_notifier,
    + &cte->nb);
    +
    + throttler_teardown(cte->throttler);
    +
    + return 0;
    +}
    +
    +#ifdef CONFIG_OF
    +static const struct of_device_id cros_ec_throttler_of_match[] = {
    + { .compatible = "google,cros-ec-throttler" },
    + { /* sentinel */ }
    +};
    +MODULE_DEVICE_TABLE(of, cros_ec_throttler_of_match);
    +#endif /* CONFIG_OF */
    +
    +static struct platform_driver cros_ec_throttler_driver = {
    + .driver = {
    + .name = "cros-ec-throttler",
    + .of_match_table = of_match_ptr(cros_ec_throttler_of_match),
    + },
    + .probe = cros_ec_throttler_probe,
    + .remove = cros_ec_throttler_remove,
    +};
    +
    +module_platform_driver(cros_ec_throttler_driver);
    +
    +MODULE_LICENSE("GPL");
    +MODULE_AUTHOR("Matthias Kaehlcke <mka@chromium.org>");
    +MODULE_DESCRIPTION("Chrome OS EC Throttler");
    --
    2.17.0.921.gf22659ad46-goog
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