Re: [PATCH v6 03/11] firmware: xilinx: Add zynqmp IOCTL API for device control

From: Sudeep Holla <sudeep.holla@arm.com>
To: Jolly Shah <jolly.shah@xilinx.com>,
	ard.biesheuvel@linaro.org, mingo@kernel.org,
	gregkh@linuxfoundation.org, matt@codeblueprint.co.uk,
	hkallweit1@gmail.com, keescook@chromium.org,
	dmitry.torokhov@gmail.com, mturquette@baylibre.com,
	sboyd@codeaurora.org, michal.simek@xilinx.com,
	robh+dt@kernel.org, mark.rutland@arm.com,
	linux-clk@vger.kernel.org
Cc: Sudeep Holla <sudeep.holla@arm.com>,
	rajanv@xilinx.com, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
	Jolly Shah <jollys@xilinx.com>
Subject: Re: [PATCH v6 03/11] firmware: xilinx: Add zynqmp IOCTL API for device control
Date: Thu, 10 May 2018 15:09:12 +0100	[thread overview]
Message-ID: <c351b9a3-5f26-7202-7171-0dcc7adef7c0@arm.com> (raw)
In-Reply-To: <1523389127-14243-4-git-send-email-jollys@xilinx.com>

On 10/04/18 20:38, Jolly Shah wrote:
> From: Rajan Vaja <rajanv@xilinx.com>
> 
> Add ZynqMP firmware IOCTL API to control and configure
> devices like PLLs, SD, Gem, etc.
> 
> Signed-off-by: Rajan Vaja <rajanv@xilinx.com>
> Signed-off-by: Jolly Shah <jollys@xilinx.com>
> ---
>  drivers/firmware/xilinx/zynqmp.c     | 20 ++++++++++++++++++++
>  include/linux/firmware/xlnx-zynqmp.h |  2 ++
>  2 files changed, 22 insertions(+)
> 
> diff --git a/drivers/firmware/xilinx/zynqmp.c b/drivers/firmware/xilinx/zynqmp.c
> index 490561a..44b43fa 100644
> --- a/drivers/firmware/xilinx/zynqmp.c
> +++ b/drivers/firmware/xilinx/zynqmp.c
> @@ -239,8 +239,28 @@ static int get_set_conduit_method(struct device_node *np)
>  	return 0;
>  }
>  
> +/**
> + * zynqmp_pm_ioctl() - PM IOCTL API for device control and configs
> + * @node_id:	Node ID of the device
> + * @ioctl_id:	ID of the requested IOCTL
> + * @arg1:	Argument 1 to requested IOCTL call
> + * @arg2:	Argument 2 to requested IOCTL call
> + * @out:	Returned output value
> + *
> + * This function calls IOCTL to firmware for device control and configuration.
> + *
> + * Return: Returns status, either success or error+reason
> + */
> +static int zynqmp_pm_ioctl(u32 node_id, u32 ioctl_id, u32 arg1, u32 arg2,
> +			   u32 *out)
> +{
> +	return zynqmp_pm_invoke_fn(PM_IOCTL, node_id, ioctl_id,
> +				   arg1, arg2, out);
> +}
> +
>  static const struct zynqmp_eemi_ops eemi_ops = {
>  	.get_api_version = zynqmp_pm_get_api_version,
> +	.ioctl = zynqmp_pm_ioctl,
>  };
>  
>  /**
> diff --git a/include/linux/firmware/xlnx-zynqmp.h b/include/linux/firmware/xlnx-zynqmp.h
> index cb63bed..2eec6e7 100644
> --- a/include/linux/firmware/xlnx-zynqmp.h
> +++ b/include/linux/firmware/xlnx-zynqmp.h
> @@ -34,6 +34,7 @@
>  
>  enum pm_api_id {
>  	PM_GET_API_VERSION = 1,
> +	PM_IOCTL = 34,

I am not for this API. IIUC there are more fined grained well defined
APIs(if I am not wrong from enum 2 upto 33). This is open ended API
which allows user to do whatever setting it needs. And that defeats the
purpose of other APIs.

I will look through the series for the usage of this to understand this
better, but I am guessing how it can be (ab)used.

-- 
Regards,
Sudeep