linux-kernel - Re: [PATCH v3 4/4] mfd: cros_ec: instantiate properly CrOS Touchpad MCU device

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Message-ID: <20190408181939.GB18975@google.com>
Date:   Mon, 8 Apr 2019 11:19:39 -0700
From:   Benson Leung <bleung@...gle.com>
To:     Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc:     lee.jones@...aro.org, gwendal@...omium.org, bleung@...omium.org,
        linux-kernel@...r.kernel.org, groeck@...omium.org,
        kernel@...labora.com, dtor@...omium.org,
        rushikesh.s.kadam@...el.com, Wei-Ning Huang <wnhuang@...gle.com>
Subject: Re: [PATCH v3 4/4] mfd: cros_ec: instantiate properly CrOS Touchpad
 MCU device

Hi Enric,

On Mon, Apr 08, 2019 at 11:41:41AM +0200, Enric Balletbo i Serra wrote:
> Support Touchpad MCU as a special of CrOS EC devices. The current
> Touchpad MCU is used on Eve Chromebook and used the same protocol as
> other CrOS EC devices.
> 
> When a MCU has touchpad support (aka EC_FEATURE_TOUCHPAD), it is
> instantiated as a special CrOS EC device with device name 'cros_tp'. So
> regardless of the probing order between the actual cros_ec and cros_tp,
> the userspace and other kernel drivers should not confuse them.
> 
> Signed-off-by: Wei-Ning Huang <wnhuang@...gle.com>
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>

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

> ---
> 
> Changes in v3: None
> Changes in v2: None
> 
>  drivers/mfd/cros_ec_dev.c   | 10 ++++++++++
>  include/linux/mfd/cros_ec.h |  1 +
>  2 files changed, 11 insertions(+)
> 
> diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
> index 79746e817cdb..be827910e9d0 100644
> --- a/drivers/mfd/cros_ec_dev.c
> +++ b/drivers/mfd/cros_ec_dev.c
> @@ -659,6 +659,16 @@ static int ec_device_probe(struct platform_device *pdev)
>  		ec_platform->ec_name = CROS_EC_DEV_ISH_NAME;
>  	}
>  
> +	/* Check whether this is actually a Touchpad MCU rather than an EC */
> +	if (cros_ec_check_features(ec, EC_FEATURE_TOUCHPAD)) {
> +		dev_info(dev, "CrOS Touchpad MCU detected.\n");
> +		/*
> +		 * Help userspace differentiating ECs from TP MCU,
> +		 * regardless of the probing order.
> +		 */
> +		ec_platform->ec_name = CROS_EC_DEV_TP_NAME;
> +	}
> +
>  	/*
>  	 * Add the class device
>  	 * Link to the character device for creating the /dev entry
> diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> index b393bd4e4b73..981381fbb3fd 100644
> --- a/include/linux/mfd/cros_ec.h
> +++ b/include/linux/mfd/cros_ec.h
> @@ -26,6 +26,7 @@
>  #define CROS_EC_DEV_FP_NAME	"cros_fp"
>  #define CROS_EC_DEV_ISH_NAME	"cros_ish"
>  #define CROS_EC_DEV_PD_NAME	"cros_pd"
> +#define CROS_EC_DEV_TP_NAME	"cros_tp"
>  
>  /*
>   * The EC is unresponsive for a time after a reboot command.  Add a
> -- 
> 2.20.1
> 

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

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