linux-kernel - Re: [PATCH v2 3/3] mfd: cros_ec: Don't add cros_ec

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Message-ID: <aOVtbDOl1w4RXEfi@google.com>
Date: Tue, 7 Oct 2025 19:43:40 +0000
From: Benson Leung <bleung@...gle.com>
To: Jameson Thies <jthies@...gle.com>
Cc: akuchynski@...omium.org, abhishekpandit@...omium.org,
	krzk+dt@...nel.org, robh@...nel.org, bleung@...omium.org,
	heikki.krogerus@...ux.intel.com, ukaszb@...omium.org,
	tzungbi@...nel.org, devicetree@...r.kernel.org,
	chrome-platform@...ts.linux.dev, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] mfd: cros_ec: Don't add cros_ec_ucsi if it is
 defined in OF or ACPI

On Wed, Oct 01, 2025 at 07:33:43PM +0000, Jameson Thies wrote:
> On devices with a UCSI PPM in the EC, check for cros_ec_ucsi to be
> defined in the OF device tree or an ACPI node. If it is defined by
> either OF or ACPI, it does not need to be added as a subdevice of
> cros_ec_dev.
> 
> Signed-off-by: Jameson Thies <jthies@...gle.com>

Reviewed-by: Benson Leung <bleung@...omium.org>


> ---
>  drivers/mfd/cros_ec_dev.c | 40 ++++++++++++++++++++++++++++++++++-----
>  1 file changed, 35 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
> index dc80a272726b..b0523f6541d2 100644
> --- a/drivers/mfd/cros_ec_dev.c
> +++ b/drivers/mfd/cros_ec_dev.c
> @@ -5,6 +5,7 @@
>   * Copyright (C) 2014 Google, Inc.
>   */
>  
> +#include <linux/acpi.h>
>  #include <linux/dmi.h>
>  #include <linux/kconfig.h>
>  #include <linux/mfd/core.h>
> @@ -131,11 +132,6 @@ static const struct cros_feature_to_cells cros_subdevices[] = {
>  		.mfd_cells	= cros_ec_rtc_cells,
>  		.num_cells	= ARRAY_SIZE(cros_ec_rtc_cells),
>  	},
> -	{
> -		.id		= EC_FEATURE_UCSI_PPM,
> -		.mfd_cells	= cros_ec_ucsi_cells,
> -		.num_cells	= ARRAY_SIZE(cros_ec_ucsi_cells),
> -	},
>  	{
>  		.id		= EC_FEATURE_HANG_DETECT,
>  		.mfd_cells	= cros_ec_wdt_cells,
> @@ -177,6 +173,16 @@ static const struct mfd_cell cros_ec_vbc_cells[] = {
>  	{ .name = "cros-ec-vbc", }
>  };
>  
> +static int ucsi_acpi_match(struct device *dev, const void *data)
> +{
> +	struct acpi_device_id ucsi_acpi_device_ids[] = {
> +		{ "GOOG0021", 0 },
> +		{"", 0},
> +	};
> +	return !!acpi_match_device(ucsi_acpi_device_ids, dev);
> +}
> +
> +
>  static void cros_ec_class_release(struct device *dev)
>  {
>  	kfree(to_cros_ec_dev(dev));
> @@ -264,6 +270,30 @@ static int ec_device_probe(struct platform_device *pdev)
>  		}
>  	}
>  
> +	/*
> +	 * FW nodes can load cros_ec_ucsi, but early PDC devices did not define
> +	 * the required nodes. On PDC systems without FW nodes for cros_ec_ucsi,
> +	 * the driver should be added as an mfd subdevice.
> +	 */
> +	if (cros_ec_check_features(ec, EC_FEATURE_USB_PD) &&
> +	    cros_ec_check_features(ec, EC_FEATURE_UCSI_PPM)) {
> +		struct device *acpi_dev = device_find_child(ec->ec_dev->dev,
> +							    NULL,
> +							    ucsi_acpi_match);
> +
> +		if (!!acpi_dev) {
> +			put_device(acpi_dev);
> +		} else if (!of_find_compatible_node(NULL, NULL,
> +						    "google,cros-ec-ucsi")) {
> +			retval = mfd_add_hotplug_devices(
> +				ec->dev, cros_ec_ucsi_cells,
> +				ARRAY_SIZE(cros_ec_ucsi_cells));
> +			if (retval)
> +				dev_warn(ec->dev,
> +				    "failed to add cros_ec_ucsi: %d\n", retval);
> +		}
> +	}
> +
>  	/*
>  	 * UCSI provides power supply information so we don't need to separately
>  	 * load the cros_usbpd_charger driver.
> -- 
> 2.51.0.618.g983fd99d29-goog
> 

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