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From:   Enric Balletbo i Serra <enric.balletbo@collabora.com>
Subject: Re: [PATCH v7 1/3] platform: chrome: Add cros-usbpd-notify driver
To:     Prashant Malani <pmalani@chromium.org>, groeck@chromium.org,
        bleung@chromium.org, lee.jones@linaro.org, sre@kernel.org
Cc:     linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
        Jon Flatley <jflat@chromium.org>,
        Gwendal Grignou <gwendal@chromium.org>
References: <20200117002820.56872-1-pmalani@chromium.org>
Message-ID: <c338d46d-5600-a53e-5a04-12100f5628b1@collabora.com>
Date:   Tue, 21 Jan 2020 13:10:06 +0100
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Hi Prashant,

Sorry, I am still having issues with this patch. It doesn't work as expected on
my Samsung Chromebook Plus because the below code tries to register twice the
driver and then hangs for some reason.

  [    9.381368] Error: Driver 'cros-usbpd-notify' is already registered,
aborting...

Also I have the problem that I don't have any x86 device using the
cros_usbpd_charger so I can't really test for x86.

Let me propose some changes and let's see if it works for you.

On 17/1/20 1:28, Prashant Malani wrote:
> 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 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@chromium.org>
> Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
> Reviewed-by: Benson Leung <bleung@chromium.org>
> Signed-off-by: Jon Flatley <jflat@chromium.org>
> Signed-off-by: Prashant Malani <pmalani@chromium.org>
> ---
> 
> Changes in v7(pmalani@chromium.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@chromium.org):
> - Fix build error from typo in cros_usbpd_notify_acpi_device_ids
>   variable name.
> 
> Changes in v5(pmalani@chromium.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@chromium.org):
> - No code changes, but added new version so that versioning is
>   consistent with the next patch in the series.
> 
> Changes in v3 (pmalani@chromium.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@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/platform/chrome/Kconfig               |  10 +
>  drivers/platform/chrome/Makefile              |   1 +
>  drivers/platform/chrome/cros_usbpd_notify.c   | 180 ++++++++++++++++++
>  .../linux/platform_data/cros_usbpd_notify.h   |  17 ++
>  4 files changed, 208 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..89df6c991089d 100644
> --- a/drivers/platform/chrome/Kconfig
> +++ b/drivers/platform/chrome/Kconfig
> @@ -226,6 +226,16 @@ 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
> +	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

Please use a max length of 80 characters.

> +	  will get initialized on ECs which support the feature
> +	  EC_FEATURE_USB_PD.
> +

Please add:

          To compile this driver as a module, choose M here: the
          module will be called cros_usbpd_notify.

So checkpatch --strict is more happy.

>  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..4705164e38bf4
> --- /dev/null
> +++ b/drivers/platform/chrome/cros_usbpd_notify.c
> @@ -0,0 +1,180 @@
> +// 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_commands.h>

I think this include is not needed.

> +#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);
> +
> +

Please don't use multiple blank lines

> +/**
> + * 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 */
> +
> +#ifdef CONFIG_OF
> +

I propose to remove this ...

> +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;
> +

What about this?

+       /*
+        * We only need to register the notifier if we are really using
+        * device-tree, otherwise, for ACPI case it will register an
+        * acpi_driver and use the .notify callback.
+        */
+       if (IS_ENABLED(CONFIG_OF) && !dev->of_node)
+               return 0;
+

> +	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);
> +

Only unregister for the device-tree case

+       if (IS_ENABLED(CONFIG_OF) && dev->of_node)

> +	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,
> +};
> +
> +#endif /* CONFIG_OF */
> +
> +static int __init cros_usbpd_notify_init(void)
> +{
> +	int ret = 0;
> +#ifdef CONFIG_OF
> +	ret = platform_driver_register(&cros_usbpd_notify_plat_driver);
> +	if (ret != 0)
> +		pr_err("cros-usbpd-notify platform driver register failed.\n");
> +#endif


To simplify the ifdery, let's register the platform driver always, it'll be noop
in ACPI case.

        int ret;

        ret = platform_driver_register(&cros_usbpd_notify_driver);
        if (ret < 0)
                return ret;


> +#ifdef CONFIG_ACPI
> +	ret = acpi_bus_register_driver(&cros_usbpd_notify_acpi_driver);
> +	if (ret != 0)
> +		pr_err("cros-usbpd-notify ACPI driver register failed.\n");
> +#endif
> +	return ret;

And register the ACPI driver if CONFIG_ACPI is enabled, note that the error is
ignored because that call will fail on device-tree based devices with
CONFIG_ACPI enabled.

+#ifdef CONFIG_ACPI
+       acpi_bus_unregister_driver(&cros_usbpd_notify_acpi_driver)
+#endif

> +}
> +
> +static void __exit cros_usbpd_notify_exit(void)
> +{
> +#ifdef CONFIG_OF
> +	platform_driver_unregister(&cros_usbpd_notify_plat_driver);
> +#endif
> +#ifdef CONFIG_ACPI
> +	acpi_bus_unregister_driver(&cros_usbpd_notify_acpi_driver);
> +#endif

And for the remove, only unregister the acpi driver if CONFIG_ACPI is enabled.

+#ifdef CONFIG_ACPI
+       acpi_bus_unregister_driver(&cros_usbpd_notify_acpi_driver);
+#endif
+       platform_driver_unregister(&cros_usbpd_notify_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@chromium.org>");
> +MODULE_ALIAS("platform:" DRV_NAME);


Double check that the code builds with different CONFIG options. I didn't check
the ifery involved.

  CONFIG_ACPI && CONFIG_OF
  CONFIG_ACPI && !CONFIG_OF
  !CONFIG_ACPI && CONFIG_OF

And we need to _make sure_ that the platform driver is _only_ instantiated via
cros_ec_dev when we are really under a device-tree based device, so the check
probably should be something like this:


diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
index 39e611695053..c43026754718 100644
--- a/drivers/mfd/cros_ec_dev.c
+++ b/drivers/mfd/cros_ec_dev.c
@@ -211,7 +211,7 @@ static int ec_device_probe(struct platform_device *pdev)
         * explicitly added on platforms that don't have the PD notifier ACPI
         * device entry defined.
         */
-       if (IS_ENABLED(CONFIG_OF)) {
+       if (IS_ENABLED(CONFIG_OF) && &pdev->dev.of_node) {
                if (cros_ec_check_features(ec, EC_FEATURE_USB_PD)) {
                        retval = mfd_add_hotplug_devices(ec->dev,
                                        cros_usbpd_notify_cells,


> 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 */
> 

Cheers,
 Enric