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Subject[PATCH v5 11/12] 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>
Reviewed-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Brian Norris <briannorris@chromium.org>
---
Changes in v5:
- none

Changes in v4:
- adapt to parent being struct cros_ec_dev instead of struct
cros_ec_device
- added 'Reviewed-by: Brian Norris <briannorris@chromium.org>' tag

Changes in v3:
- change module license to GPL v2 as in the SPDX identifier
- don't instantiate the throttler through the DT (instantiation
by CrOS EC MFD in a separate patch)

Changes in v2:
- added SPDX line instead of license boiler-plate
- use macro to avoid splitting line
- changed variable name for throttler from 'cte' to 'ce_thr'
- formatting fixes
- Kconfig: removed odd dashes around 'help'
- added 'Reviewed-by' tag
---
drivers/misc/throttler/Kconfig | 10 ++
drivers/misc/throttler/Makefile | 1 +
drivers/misc/throttler/cros_ec_throttler.c | 111 +++++++++++++++++++++
3 files changed, 122 insertions(+)
create mode 100644 drivers/misc/throttler/cros_ec_throttler.c

diff --git a/drivers/misc/throttler/Kconfig b/drivers/misc/throttler/Kconfig
index 8b2e63b2ef48..ef984c96f67b 100644
--- a/drivers/misc/throttler/Kconfig
+++ b/drivers/misc/throttler/Kconfig
@@ -20,4 +20,14 @@ menuconfig THROTTLER_DEBUG

Choose N unless you want to debug throttler drivers.

+config CROS_EC_THROTTLER
+ tristate "Throttler event monitor for the Chrome OS Embedded Controller"
+ 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..82a25415a264
--- /dev/null
+++ b/drivers/misc/throttler/cros_ec_throttler.c
@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for throttling triggered by events from the Chrome OS Embedded
+ * Controller.
+ *
+ * Copyright (C) 2018 Google, Inc.
+ */
+
+#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>
+
+#define nb_to_ce_thr(nb) container_of(nb, struct cros_ec_throttler, nb)
+
+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 *ce_thr = nb_to_ce_thr(nb);
+ u32 host_event;
+
+ host_event = cros_ec_get_host_event(ce_thr->ec);
+ if (host_event & EC_HOST_EVENT_MASK(EC_HOST_EVENT_THROTTLE_START)) {
+ throttler_set_level(ce_thr->throttler, 1);
+
+ return NOTIFY_OK;
+ } else if (host_event &
+ EC_HOST_EVENT_MASK(EC_HOST_EVENT_THROTTLE_STOP)) {
+ throttler_set_level(ce_thr->throttler, 0);
+
+ return NOTIFY_OK;
+ }
+
+ return NOTIFY_DONE;
+}
+
+static int cros_ec_throttler_probe(struct platform_device *pdev)
+{
+ struct cros_ec_throttler *ce_thr;
+ struct device *dev = &pdev->dev;
+ struct cros_ec_dev *ec;
+ int ret;
+
+ ce_thr = devm_kzalloc(dev, sizeof(*ce_thr), GFP_KERNEL);
+ if (!ce_thr)
+ return -ENOMEM;
+
+ ec = dev_get_drvdata(pdev->dev.parent);
+ ce_thr->ec = ec->ec_dev;
+
+ /*
+ * The core code uses the DT node of the throttler to identify its
+ * throttling devices and rates. The CrOS EC throttler is a sub-device
+ * of the CrOS EC MFD device and doesn't have its own device node. Use
+ * the node of the MFD device instead.
+ */
+ dev->of_node = ce_thr->ec->dev->of_node;
+
+ ce_thr->throttler = throttler_setup(dev);
+ if (IS_ERR(ce_thr->throttler))
+ return PTR_ERR(ce_thr->throttler);
+
+ dev_set_drvdata(dev, ce_thr);
+
+ ce_thr->nb.notifier_call = cros_ec_throttler_event;
+ ret = blocking_notifier_chain_register(&ce_thr->ec->event_notifier,
+ &ce_thr->nb);
+ if (ret < 0) {
+ dev_err(dev, "failed to register notifier\n");
+ throttler_teardown(ce_thr->throttler);
+ return ret;
+ }
+
+ return 0;
+}
+
+static int cros_ec_throttler_remove(struct platform_device *pdev)
+{
+ struct cros_ec_throttler *ce_thr = platform_get_drvdata(pdev);
+
+ blocking_notifier_chain_unregister(&ce_thr->ec->event_notifier,
+ &ce_thr->nb);
+
+ throttler_teardown(ce_thr->throttler);
+
+ return 0;
+}
+
+static struct platform_driver cros_ec_throttler_driver = {
+ .driver = {
+ .name = "cros-ec-throttler",
+ },
+ .probe = cros_ec_throttler_probe,
+ .remove = cros_ec_throttler_remove,
+};
+
+module_platform_driver(cros_ec_throttler_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Matthias Kaehlcke <mka@chromium.org>");
+MODULE_DESCRIPTION("Chrome OS EC Throttler");
--
2.18.0.203.gfac676dfb9-goog
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