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Date: Fri, 24 May 2024 12:34:29 +0200
From: Sascha Hauer <s.hauer@pengutronix.de>
To: Pankaj Gupta <pankaj.gupta@nxp.com>
Cc: Jonathan Corbet <corbet@lwn.net>, Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>, Shawn Guo <shawnguo@kernel.org>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Fabio Estevam <festevam@gmail.com>, Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
	imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 4/5] firmware: imx: add driver for NXP EdgeLock Enclave
Message-ID: <ZlBtNSeh2VyZsVxq@pengutronix.de>
References: <20240523-imx-se-if-v2-0-5a6fd189a539@nxp.com>
 <20240523-imx-se-if-v2-4-5a6fd189a539@nxp.com>
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In-Reply-To: <20240523-imx-se-if-v2-4-5a6fd189a539@nxp.com>

On Thu, May 23, 2024 at 04:19:35PM +0530, Pankaj Gupta wrote:
> NXP hardware IP(s) for secure-enclaves like Edgelock Enclave(ELE),
> are embedded in the SoC to support the features like HSM, SHE & V2X,
> using message based communication interface.
> 
> The secure enclave FW communicates on a dedicated messaging unit(MU)
> based interface(s) with application core, where kernel is running.
> It exists on specific i.MX processors. e.g. i.MX8ULP, i.MX93.
> 
> This patch adds the driver for communication interface to secure-enclave,
> for exchanging messages with NXP secure enclave HW IP(s) like EdgeLock
> Enclave (ELE) from Kernel-space, used by kernel management layers like
> - DM-Crypt.
> 
> Signed-off-by: Pankaj Gupta <pankaj.gupta@nxp.com>
> ---
>  drivers/firmware/imx/Kconfig        |  12 +
>  drivers/firmware/imx/Makefile       |   2 +
>  drivers/firmware/imx/ele_base_msg.c | 286 +++++++++++++++++++
>  drivers/firmware/imx/ele_base_msg.h |  92 +++++++
>  drivers/firmware/imx/ele_common.c   | 239 ++++++++++++++++
>  drivers/firmware/imx/ele_common.h   |  43 +++
>  drivers/firmware/imx/se_ctrl.c      | 531 ++++++++++++++++++++++++++++++++++++
>  drivers/firmware/imx/se_ctrl.h      |  99 +++++++
>  include/linux/firmware/imx/se_api.h |  14 +
>  9 files changed, 1318 insertions(+)
> 

> +static int se_probe_if_cleanup(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct se_if_priv *priv;
> +	int ret = 0;
> +
> +	priv = dev_get_drvdata(dev);
> +	if (!priv) {
> +		ret = 0;
> +		dev_dbg(dev, "SE-MU Priv data is NULL;");
> +		return ret;
> +	}
> +
> +	if (priv->tx_chan)
> +		mbox_free_channel(priv->tx_chan);
> +	if (priv->rx_chan)
> +		mbox_free_channel(priv->rx_chan);
> +
> +	/* free the buffer in se remove, previously allocated
> +	 * in se probe to store encrypted IMEM
> +	 */
> +	if (priv->imem.buf) {
> +		dmam_free_coherent(dev,
> +				   ELE_IMEM_SIZE,
> +				   priv->imem.buf,
> +				   priv->imem.phyaddr);
> +		priv->imem.buf = NULL;
> +	}
> +
> +	if (priv->flags & RESERVED_DMA_POOL) {
> +		of_reserved_mem_device_release(dev);

You can call this unconditionally, no need to keep track if you called
of_reserved_mem_device_init() successfully.

> +
> +static int se_if_probe(struct platform_device *pdev)
> +{
> +	struct imx_se_node_info_list *info_list;
> +	struct device *dev = &pdev->dev;
> +	struct imx_se_node_info *info;
> +	struct se_if_priv *priv;
> +	u32 idx;
> +	int ret;
> +
> +	if (of_property_read_u32(dev->of_node, "reg", &idx)) {
> +		ret = -EINVAL;
> +		goto exit;
> +	}
> +
> +	info_list = (struct imx_se_node_info_list *)
> +			device_get_match_data(dev);
> +	info = get_imx_se_node_info(info_list, idx);
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv) {
> +		ret = -ENOMEM;
> +		goto exit;
> +	}
> +
> +	dev_set_drvdata(dev, priv);
> +
> +	/* Mailbox client configuration */
> +	priv->se_mb_cl.dev		= dev;
> +	priv->se_mb_cl.tx_block		= false;
> +	priv->se_mb_cl.knows_txdone	= true;
> +	priv->se_mb_cl.rx_callback	= se_if_rx_callback;
> +
> +	ret = se_if_request_channel(dev, &priv->tx_chan,
> +			&priv->se_mb_cl, info->mbox_tx_name);
> +	if (ret)
> +		goto exit;
> +
> +	ret = se_if_request_channel(dev, &priv->rx_chan,
> +			&priv->se_mb_cl, info->mbox_rx_name);
> +	if (ret)
> +		goto exit;
> +
> +	priv->dev = dev;
> +	priv->info = info;
> +
> +	/* Initialize the mutex. */
> +	mutex_init(&priv->se_if_lock);
> +	mutex_init(&priv->se_if_cmd_lock);
> +
> +	priv->cmd_receiver_dev = NULL;
> +	priv->waiting_rsp_dev = NULL;
> +	priv->max_dev_ctx = info->max_dev_ctx;
> +	priv->cmd_tag = info->cmd_tag;
> +	priv->rsp_tag = info->rsp_tag;
> +	priv->mem_pool_name = info->pool_name;
> +	priv->success_tag = info->success_tag;
> +	priv->base_api_ver = info->base_api_ver;
> +	priv->fw_api_ver = info->fw_api_ver;
> +
> +	init_completion(&priv->done);
> +	spin_lock_init(&priv->lock);
> +
> +	if (info->reserved_dma_ranges) {
> +		ret = of_reserved_mem_device_init(dev);
> +		if (ret) {
> +			dev_err(dev,
> +				"failed to init reserved memory region %d\n",
> +				ret);
> +			priv->flags &= (~RESERVED_DMA_POOL);
> +			goto exit;
> +		}
> +		priv->flags |= RESERVED_DMA_POOL;
> +	}

Can't this be optional? Why do you need to reserve memory in the device
tree for it?

Sascha

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