linux-kernel - Re: [PATCH v8 7/7] mfd: cros_ec: differentiate SCP from EC by feature bit.

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Message-ID: <9bf20470-e5f6-7c12-9cc3-d9c6041a3bf8@collabora.com>
Date:   Mon, 15 Apr 2019 17:29:54 +0200
From:   Enric Balletbo i Serra <enric.balletbo@...labora.com>
To:     Pi-Hsun Shih <pihsun@...omium.org>
Cc:     Lee Jones <lee.jones@...aro.org>,
        Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v8 7/7] mfd: cros_ec: differentiate SCP from EC by feature
 bit.



On 12/4/19 9:18, Pi-Hsun Shih wrote:
> System Companion Processor (SCP) is Cortex M4 co-processor on some
> MediaTek platform that can run EC-style firmware. Since a SCP and EC
> would both exist on a system, and use the cros_ec_dev driver, we need to
> differentiate between them for the userspace, or they would both be
> registered at /dev/cros_ec, causing a conflict.
> 
> Signed-off-by: Pi-Hsun Shih <pihsun@...omium.org>

Acked-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>

Lee, there are several patches touching these files right now so you could have
to solve some trivial conflicts. If you want I send a series with all that apply
cleanly just let me know.

Thanks,
 Enric


> ---
> Changes from v7:
>  - Address comments in v7.
>  - Rebase the series onto https://lore.kernel.org/patchwork/patch/1059196/.
> 
> Changes from v6:
>  - No change.
> 
> Changes from v5:
>  - No change.
> 
> Changes from v4:
>  - No change.
> 
> Changes from v3:
>  - No change.
> 
> Changes from v2:
>  - No change.
> 
> Changes from v1:
>  - New patch extracted from Patch 5.
> ---
>  drivers/mfd/cros_ec_dev.c            | 10 ++++++++++
>  include/linux/mfd/cros_ec.h          |  1 +
>  include/linux/mfd/cros_ec_commands.h |  2 +-
>  3 files changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
> index a3b319913097..5b52b648abf2 100644
> --- a/drivers/mfd/cros_ec_dev.c
> +++ b/drivers/mfd/cros_ec_dev.c
> @@ -432,6 +432,16 @@ static int ec_device_probe(struct platform_device *pdev)
>  		ec_platform->ec_name = CROS_EC_DEV_ISH_NAME;
>  	}
>  
> +	/* Check whether this is actually a SCP rather than an EC. */
> +	if (cros_ec_check_features(ec, EC_FEATURE_SCP)) {
> +		dev_info(dev, "CrOS SCP MCU detected.\n");
> +		/*
> +		 * Help userspace differentiating ECs from SCP,
> +		 * regardless of the probing order.
> +		 */
> +		ec_platform->ec_name = CROS_EC_DEV_SCP_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 109292a60499..a3e3d6beb19a 100644
> --- a/include/linux/mfd/cros_ec.h
> +++ b/include/linux/mfd/cros_ec.h
> @@ -25,6 +25,7 @@
>  #define CROS_EC_DEV_NAME "cros_ec"
>  #define CROS_EC_DEV_PD_NAME "cros_pd"
>  #define CROS_EC_DEV_ISH_NAME "cros_ish"
> +#define CROS_EC_DEV_SCP_NAME "cros_scp"
>  
>  /*
>   * The EC is unresponsive for a time after a reboot command.  Add a
> diff --git a/include/linux/mfd/cros_ec_commands.h b/include/linux/mfd/cros_ec_commands.h
> index d5bf909af661..80a904ed7d7f 100644
> --- a/include/linux/mfd/cros_ec_commands.h
> +++ b/include/linux/mfd/cros_ec_commands.h
> @@ -884,7 +884,7 @@ enum ec_feature_code {
>  	EC_FEATURE_REFINED_TABLET_MODE_HYSTERESIS = 37,
>  	/* EC supports audio codec. */
>  	EC_FEATURE_AUDIO_CODEC = 38,
> -	/* EC Supports SCP. */
> +	/* The MCU is a System Companion Processor (SCP). */
>  	EC_FEATURE_SCP = 39,
>  	/* The MCU is an Integrated Sensor Hub */
>  	EC_FEATURE_ISH = 40,
>