Message-ID: <20200127184439.GA150048@google.com>
Date:   Mon, 27 Jan 2020 10:44:39 -0800
From:   Benson Leung <bleung@...gle.com>
To:     Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc:     Prashant Malani <pmalani@...omium.org>, groeck@...omium.org,
        bleung@...omium.org, lee.jones@...aro.org, sre@...nel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        Jon Flatley <jflat@...omium.org>,
        Gwendal Grignou <gwendal@...omium.org>
Subject: Re: [PATCH v8 1/4] platform: chrome: Add cros-usbpd-notify driver

On Mon, Jan 27, 2020 at 03:58:42PM +0100, Enric Balletbo i Serra wrote:
> Hi Prashant,
> 
> On 25/1/20 0:18, Prashant Malani wrote:
> > From: Jon Flatley <jflat@...omium.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 platforms that don't have the ACPI device defined, the driver gets
> > instantiated for ECs which support the EC_FEATURE_USB_PD feature bit,
> > and the notification events will get delivered using the MKBP event
> > handling mechanism.
> > 
> > Co-Developed-by: Prashant Malani <pmalani@...omium.org>
> > Reviewed-by: Gwendal Grignou <gwendal@...omium.org>
> > Reviewed-by: Benson Leung <bleung@...omium.org>
> > Signed-off-by: Jon Flatley <jflat@...omium.org>
> > Signed-off-by: Prashant Malani <pmalani@...omium.org>
> > ---
> > 
> 
> Just a nit below but for my own reference:
> 
> Acked-for-chrome-platform: Enric Balletbo i Serra <enric.balletbo@...labora.com>
> 
> I am not sure if we're on time to get this merged on this merge window, though.

I'm OK with creating a branch for this series and merging it into
chrome-platform-5.7 once Linus releases v5.6-rc1 late next week.

> 
> Thanks,
>  Enric
> 
> > Changes in v8(pmalani@...omium.org):
> > - Fix style nits.
> > - Remove unrequired header.
> > - Remove #ifdef CONFIG_OF dependency for platform driver registration.
> > - Add module compile text to Kconfig help section.
> > 
> > Changes in v7(pmalani@...omium.org):
> > - Removed use of module_platform_driver() and module_acpi_driver() since
> >   that was causing redefinition compilation errors on arm64 defconfig.
> >   Instead, explicitly defined the init and exit routines and
> >   register/unregister the platform and ACPI drivers there.
> > - Alphabetize #include header.
> > 
> > Changes in v6(pmalani@...omium.org):
> > - Fix build error from typo in cros_usbpd_notify_acpi_device_ids
> >   variable name.
> > 
> > Changes in v5(pmalani@...omium.org):
> > - Split the driver into platform and ACPI variants, each enclosed by
> >   CONFIG_OF and CONFIG_ACPI #ifdefs respectively.
> > - Updated the copyright year to 2020.
> > - Reworded the commit message and Kconfig description to incorporate
> >   the modified driver structure.
> > 
> > Changes in v4(pmalani@...omium.org):
> > - No code changes, but added new version so that versioning is
> >   consistent with the next patch in the series.
> > 
> > Changes in v3 (pmalani@...omium.org):
> > - Renamed driver and files from "cros_ec_pd_notify" to
> >   "cros_usbpd_notify" to be more consistent with other naming.
> > - Moved the change to include cros-usbpd-notify in the charger MFD
> >   into a separate follow-on patch.
> > 
> > Changes in v2 (pmalani@...omium.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/platform/chrome/Kconfig               |  13 ++
> >  drivers/platform/chrome/Makefile              |   1 +
> >  drivers/platform/chrome/cros_usbpd_notify.c   | 170 ++++++++++++++++++
> >  .../linux/platform_data/cros_usbpd_notify.h   |  17 ++
> >  4 files changed, 201 insertions(+)
> >  create mode 100644 drivers/platform/chrome/cros_usbpd_notify.c
> >  create mode 100644 include/linux/platform_data/cros_usbpd_notify.h
> > 
> > diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
> > index 5f57282a28da0..e45e0fe057586 100644
> > --- a/drivers/platform/chrome/Kconfig
> > +++ b/drivers/platform/chrome/Kconfig
> > @@ -226,6 +226,19 @@ config CROS_USBPD_LOGGER
> >  	  To compile this driver as a module, choose M here: the
> >  	  module will be called cros_usbpd_logger.
> >  
> > +config CROS_USBPD_NOTIFY
> > +	tristate "ChromeOS Type-C power delivery event notifier"
> > +	depends on CROS_EC
> 
> Like other cros-ec subdevices I am wondering if we should depend on
> MFD_CROS_EC_DEV instead of CROS_EC (as doesn't really makes sense to only
> depends on CROS_EC)
> 
> Also, like other cros-ec subdevices, we might be interested on have a:
> 
>        default MFD_CROS_EC_DEV
> 
> So it is selected when the cros-ec dev is configured by default.
> 
> Thanks,
> 
>  Enric
> 
> > +	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 platforms which don't have this device it
> > +	  will get initialized on ECs which support the feature
> > +	  EC_FEATURE_USB_PD.
> > +
> > +	  To compile this driver as a module, choose M here: the
> > +	  module will be called cros_usbpd_notify.
> > +
> >  source "drivers/platform/chrome/wilco_ec/Kconfig"
> >  
> >  endif # CHROMEOS_PLATFORMS
> > diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
> > index aacd5920d8a18..f6465f8ef0b5e 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-$(CONFIG_CROS_USBPD_NOTIFY)		+= cros_usbpd_notify.o
> >  
> >  obj-$(CONFIG_WILCO_EC)			+= wilco_ec/
> > diff --git a/drivers/platform/chrome/cros_usbpd_notify.c b/drivers/platform/chrome/cros_usbpd_notify.c
> > new file mode 100644
> > index 0000000000000..6ead5c62b3c5f
> > --- /dev/null
> > +++ b/drivers/platform/chrome/cros_usbpd_notify.c
> > @@ -0,0 +1,170 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Copyright 2020 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_proto.h>
> > +#include <linux/platform_data/cros_usbpd_notify.h>
> > +#include <linux/platform_device.h>
> > +
> > +#define DRV_NAME "cros-usbpd-notify"
> > +#define ACPI_DRV_NAME "GOOG0003"
> > +
> > +static BLOCKING_NOTIFIER_HEAD(cros_usbpd_notifier_list);
> > +
> > +/**
> > + * cros_usbpd_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_usbpd_register_notify(struct notifier_block *nb)
> > +{
> > +	return blocking_notifier_chain_register(&cros_usbpd_notifier_list,
> > +						nb);
> > +}
> > +EXPORT_SYMBOL_GPL(cros_usbpd_register_notify);
> > +
> > +/**
> > + * cros_usbpd_unregister_notify - Unregister notifier callback for PD events.
> > + * @nb: Notifier block pointer to unregister
> > + *
> > + * Unregister a notifier callback that was previously registered with
> > + * cros_usbpd_register_notify().
> > + */
> > +void cros_usbpd_unregister_notify(struct notifier_block *nb)
> > +{
> > +	blocking_notifier_chain_unregister(&cros_usbpd_notifier_list, nb);
> > +}
> > +EXPORT_SYMBOL_GPL(cros_usbpd_unregister_notify);
> > +
> > +#ifdef CONFIG_ACPI
> > +
> > +static int cros_usbpd_notify_add_acpi(struct acpi_device *adev)
> > +{
> > +	return 0;
> > +}
> > +
> > +static void cros_usbpd_notify_acpi(struct acpi_device *adev, u32 event)
> > +{
> > +	blocking_notifier_call_chain(&cros_usbpd_notifier_list, event, NULL);
> > +}
> > +
> > +static const struct acpi_device_id cros_usbpd_notify_acpi_device_ids[] = {
> > +	{ ACPI_DRV_NAME, 0 },
> > +	{ }
> > +};
> > +MODULE_DEVICE_TABLE(acpi, cros_usbpd_notify_acpi_device_ids);
> > +
> > +static struct acpi_driver cros_usbpd_notify_acpi_driver = {
> > +	.name = DRV_NAME,
> > +	.class = DRV_NAME,
> > +	.ids = cros_usbpd_notify_acpi_device_ids,
> > +	.ops = {
> > +		.add = cros_usbpd_notify_add_acpi,
> > +		.notify = cros_usbpd_notify_acpi,
> > +	},
> > +};
> > +
> > +#endif /* CONFIG_ACPI */
> > +
> > +static int cros_usbpd_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_usbpd_notifier_list,
> > +					     host_event, NULL);
> > +		return NOTIFY_OK;
> > +	}
> > +	return NOTIFY_DONE;
> > +}
> > +
> > +static int cros_usbpd_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_usbpd_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_usbpd_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_usbpd_notify_plat_driver = {
> > +	.driver = {
> > +		.name = DRV_NAME,
> > +	},
> > +	.probe = cros_usbpd_notify_probe_plat,
> > +	.remove = cros_usbpd_notify_remove_plat,
> > +};
> > +
> > +static int __init cros_usbpd_notify_init(void)
> > +{
> > +	int ret;
> > +
> > +	ret = platform_driver_register(&cros_usbpd_notify_plat_driver);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +#ifdef CONFIG_ACPI
> > +	acpi_bus_register_driver(&cros_usbpd_notify_acpi_driver);
> > +#endif
> > +	return 0;
> > +}
> > +
> > +static void __exit cros_usbpd_notify_exit(void)
> > +{
> > +#ifdef CONFIG_ACPI
> > +	acpi_bus_unregister_driver(&cros_usbpd_notify_acpi_driver);
> > +#endif
> > +	platform_driver_unregister(&cros_usbpd_notify_plat_driver);
> > +}
> > +
> > +module_init(cros_usbpd_notify_init);
> > +module_exit(cros_usbpd_notify_exit);
> > +
> > +MODULE_LICENSE("GPL");
> > +MODULE_DESCRIPTION("ChromeOS power delivery notifier device");
> > +MODULE_AUTHOR("Jon Flatley <jflat@...omium.org>");
> > +MODULE_ALIAS("platform:" DRV_NAME);
> > diff --git a/include/linux/platform_data/cros_usbpd_notify.h b/include/linux/platform_data/cros_usbpd_notify.h
> > new file mode 100644
> > index 0000000000000..4f2791722b6d3
> > --- /dev/null
> > +++ b/include/linux/platform_data/cros_usbpd_notify.h
> > @@ -0,0 +1,17 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * ChromeOS EC Power Delivery Notifier Driver
> > + *
> > + * Copyright 2020 Google LLC
> > + */
> > +
> > +#ifndef __LINUX_PLATFORM_DATA_CROS_USBPD_NOTIFY_H
> > +#define __LINUX_PLATFORM_DATA_CROS_USBPD_NOTIFY_H
> > +
> > +#include <linux/notifier.h>
> > +
> > +int cros_usbpd_register_notify(struct notifier_block *nb);
> > +
> > +void cros_usbpd_unregister_notify(struct notifier_block *nb);
> > +
> > +#endif  /* __LINUX_PLATFORM_DATA_CROS_USBPD_NOTIFY_H */
> > 

-- 
Benson Leung
Staff Software Engineer
Chrome OS Kernel
Google Inc.
bleung@...gle.com
Chromium OS Project
bleung@...omium.org

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