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From:   Prashant Malani <pmalani@chromium.org>
To:     enric.balletbo@collabora.com, groeck@chromium.org,
        bleung@chromium.org, lee.jones@linaro.org
Cc:     linux-kernel@vger.kernel.org, Jon Flatley <jflat@chromium.org>,
        Prashant Malani <pmalani@chromium.org>
Subject: [PATCH v2] platform: chrome: Add cros-ec-pd-notify driver
Date:   Wed, 18 Dec 2019 15:07:02 -0800
Message-Id: <20191218230701.59166-1-pmalani@chromium.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Jon Flatley <jflat@chromium.org>

ChromiumOS uses ACPI device with HID "GOOG0003" for power delivery
related events. The existing cros-usbpd-charger driver relies on these
events without ever actually receiving them on ACPI platforms. This is
because in the ChromeOS kernel trees, the GOOG0003 device is owned by an
ACPI driver that offers firmware updates to USB-C chargers.

Introduce a new platform driver under cros-ec, the ChromeOS embedded
controller, that handles these PD events and dispatches them
appropriately over a notifier chain to all drivers that use them.

On non-ACPI platforms, the driver gets instantiated for ECs which
support the EC_FEATURE_USB_PD feature bit, and on such platforms, the
notification events will get delivered using the MKBP event handling
mechanism.

Signed-off-by: Jon Flatley <jflat@chromium.org>
Signed-off-by: Prashant Malani <pmalani@chromium.org>
---

Changes in v2 (pmalani@chromium.org):
- Removed dependency on DT entry; instead, we will instantiate the
  driver on detecting EC_FEATURE_USB_PD for non-ACPI platforms.
- Modified the cros-ec-pd-notify device to be an mfd_cell under
  usbpdcharger for non-ACPI platforms. Altered the platform_probe() call
  to derive the cros EC structs appropriately.
- Replaced "usbpd_notify" with "pd_notify" in functions and structures.
- Addressed comments from upstream maintainer.

 drivers/mfd/cros_ec_dev.c                     |   3 +
 drivers/platform/chrome/Kconfig               |   9 ++
 drivers/platform/chrome/Makefile              |   1 +
 drivers/platform/chrome/cros_ec_pd_notify.c   | 151 ++++++++++++++++++
 .../linux/platform_data/cros_ec_pd_notify.h   |  17 ++
 5 files changed, 181 insertions(+)
 create mode 100644 drivers/platform/chrome/cros_ec_pd_notify.c
 create mode 100644 include/linux/platform_data/cros_ec_pd_notify.h

diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
index c4b977a5dd966..cc6a6788cd5c2 100644
--- a/drivers/mfd/cros_ec_dev.c
+++ b/drivers/mfd/cros_ec_dev.c
@@ -85,6 +85,9 @@ static const struct mfd_cell cros_ec_sensorhub_cells[] = {
 static const struct mfd_cell cros_usbpd_charger_cells[] = {
 	{ .name = "cros-usbpd-charger", },
 	{ .name = "cros-usbpd-logger", },
+#ifndef CONFIG_ACPI
+	{ .name = "cros-ec-pd-notify", },
+#endif
 };
 
 static const struct cros_feature_to_cells cros_subdevices[] = {
diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
index 5f57282a28da0..972c129b7b7ba 100644
--- a/drivers/platform/chrome/Kconfig
+++ b/drivers/platform/chrome/Kconfig
@@ -131,6 +131,15 @@ config CROS_EC_LPC
 	  To compile this driver as a module, choose M here: the
 	  module will be called cros_ec_lpcs.
 
+config CROS_EC_PD_NOTIFY
+	tristate "ChromeOS Type-C power delivery event notifier"
+	depends on CROS_EC
+	help
+	  If you say Y here, you get support for Type-C PD event notifications
+	  from the ChromeOS EC. On ACPI platorms this driver will bind to the
+	  GOOG0003 ACPI device, and on non-ACPI platforms this driver will get
+	  initialized on ECs which support the feature EC_FEATURE_USB_PD.
+
 config CROS_EC_PROTO
 	bool
 	help
diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
index aacd5920d8a18..6070baa8320ca 100644
--- a/drivers/platform/chrome/Makefile
+++ b/drivers/platform/chrome/Makefile
@@ -22,5 +22,6 @@ obj-$(CONFIG_CROS_EC_DEBUGFS)		+= cros_ec_debugfs.o
 obj-$(CONFIG_CROS_EC_SENSORHUB)		+= cros_ec_sensorhub.o
 obj-$(CONFIG_CROS_EC_SYSFS)		+= cros_ec_sysfs.o
 obj-$(CONFIG_CROS_USBPD_LOGGER)		+= cros_usbpd_logger.o
+obj-$(CONFIG_CROS_EC_PD_NOTIFY)		+= cros_ec_pd_notify.o
 
 obj-$(CONFIG_WILCO_EC)			+= wilco_ec/
diff --git a/drivers/platform/chrome/cros_ec_pd_notify.c b/drivers/platform/chrome/cros_ec_pd_notify.c
new file mode 100644
index 0000000000000..b1d98a171cff5
--- /dev/null
+++ b/drivers/platform/chrome/cros_ec_pd_notify.c
@@ -0,0 +1,151 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2019 Google LLC
+ *
+ * This driver serves as the receiver of cros_ec PD host events.
+ */
+
+#include <linux/acpi.h>
+#include <linux/module.h>
+#include <linux/mfd/cros_ec.h>
+#include <linux/platform_data/cros_ec_commands.h>
+#include <linux/platform_data/cros_ec_pd_notify.h>
+#include <linux/platform_data/cros_ec_proto.h>
+#include <linux/platform_device.h>
+
+#define DRV_NAME "cros-ec-pd-notify"
+#define ACPI_DRV_NAME "GOOG0003"
+
+static BLOCKING_NOTIFIER_HEAD(cros_ec_pd_notifier_list);
+
+/**
+ * cros_ec_pd_register_notify - Register a notifier callback for PD events.
+ * @nb: Notifier block pointer to register
+ *
+ * On ACPI platforms this corresponds to host events on the ECPD
+ * "GOOG0003" ACPI device. On non-ACPI platforms this will filter mkbp events
+ * for USB PD events.
+ *
+ * Return: 0 on success or negative error code.
+ */
+int cros_ec_pd_register_notify(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(
+			&cros_ec_pd_notifier_list, nb);
+}
+EXPORT_SYMBOL_GPL(cros_ec_pd_register_notify);
+
+
+/**
+ * cros_ec_pd_unregister_notify - Unregister notifier callback for PD events.
+ * @nb: Notifier block pointer to unregister
+ *
+ * Unregister a notifier callback that was previously registered with
+ * cros_ec_pd_register_notify().
+ */
+void cros_ec_pd_unregister_notify(struct notifier_block *nb)
+{
+	blocking_notifier_chain_unregister(&cros_ec_pd_notifier_list, nb);
+}
+EXPORT_SYMBOL_GPL(cros_ec_pd_unregister_notify);
+
+#ifdef CONFIG_ACPI
+
+static int cros_ec_pd_notify_add_acpi(struct acpi_device *adev)
+{
+	return 0;
+}
+
+static void cros_ec_pd_notify_acpi(struct acpi_device *adev, u32 event)
+{
+	blocking_notifier_call_chain(&cros_ec_pd_notifier_list, event, NULL);
+}
+
+static const struct acpi_device_id cros_ec_pd_acpi_device_ids[] = {
+	{ ACPI_DRV_NAME, 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, cros_ec_pd_acpi_device_ids);
+
+static struct acpi_driver cros_ec_pd_notify_driver = {
+	.name = DRV_NAME,
+	.class = DRV_NAME,
+	.ids = cros_ec_pd_acpi_device_ids,
+	.ops = {
+		.add = cros_ec_pd_notify_add_acpi,
+		.notify = cros_ec_pd_notify_acpi,
+	},
+};
+module_acpi_driver(cros_ec_pd_notify_driver);
+
+#else /* CONFIG_ACPI */
+
+static int cros_ec_pd_notify_plat(struct notifier_block *nb,
+		unsigned long queued_during_suspend, void *data)
+{
+	struct cros_ec_device *ec_dev = (struct cros_ec_device *)data;
+	u32 host_event = cros_ec_get_host_event(ec_dev);
+
+	if (!host_event)
+		return NOTIFY_BAD;
+
+	if (host_event & EC_HOST_EVENT_MASK(EC_HOST_EVENT_PD_MCU)) {
+		blocking_notifier_call_chain(&cros_ec_pd_notifier_list,
+				host_event, NULL);
+		return NOTIFY_OK;
+	}
+	return NOTIFY_DONE;
+}
+
+static int cros_ec_pd_notify_probe_plat(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct cros_ec_dev *ecdev = dev_get_drvdata(dev->parent);
+	struct notifier_block *nb;
+	int ret;
+
+	nb = devm_kzalloc(dev, sizeof(*nb), GFP_KERNEL);
+	if (!nb)
+		return -ENOMEM;
+
+	nb->notifier_call = cros_ec_pd_notify_plat;
+	dev_set_drvdata(dev, nb);
+
+	ret = blocking_notifier_chain_register(&ecdev->ec_dev->event_notifier,
+						nb);
+	if (ret < 0) {
+		dev_err(dev, "Failed to register notifier\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int cros_ec_pd_notify_remove_plat(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct cros_ec_dev *ecdev = dev_get_drvdata(dev->parent);
+	struct notifier_block *nb =
+		(struct notifier_block *)dev_get_drvdata(dev);
+
+	blocking_notifier_chain_unregister(&ecdev->ec_dev->event_notifier,
+			nb);
+
+	return 0;
+}
+
+static struct platform_driver cros_ec_pd_notify_driver = {
+	.driver = {
+		.name = DRV_NAME,
+	},
+	.probe = cros_ec_pd_notify_probe_plat,
+	.remove = cros_ec_pd_notify_remove_plat,
+};
+module_platform_driver(cros_ec_pd_notify_driver);
+
+#endif /* CONFIG_ACPI */
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("ChromeOS power delivery notifier device");
+MODULE_AUTHOR("Jon Flatley <jflat@chromium.org>");
+MODULE_ALIAS("platform:" DRV_NAME);
diff --git a/include/linux/platform_data/cros_ec_pd_notify.h b/include/linux/platform_data/cros_ec_pd_notify.h
new file mode 100644
index 0000000000000..907be5a130d60
--- /dev/null
+++ b/include/linux/platform_data/cros_ec_pd_notify.h
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ChromeOS EC Power Delivery Notifier Driver
+ *
+ * Copyright 2019 Google LLC
+ */
+
+#ifndef __LINUX_PLATFORM_DATA_CROS_EC_PD_NOTIFY_H
+#define __LINUX_PLATFORM_DATA_CROS_EC_PD_NOTIFY_H
+
+#include <linux/notifier.h>
+
+int cros_ec_pd_register_notify(struct notifier_block *nb);
+
+void cros_ec_pd_unregister_notify(struct notifier_block *nb);
+
+#endif  /* __LINUX_PLATFORM_DATA_CROS_EC_PD_NOTIFY_H */
-- 
2.24.1.735.g03f4e72817-goog