linux-kernel - Re: [PATCH v14 1/1] mctp pcc: Implement MCTP over PCC Transport

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Message-ID: <20250115125055.GN5497@kernel.org>
Date: Wed, 15 Jan 2025 12:50:55 +0000
From: Simon Horman <horms@...nel.org>
To: admiyo@...amperecomputing.com
Cc: Jeremy Kerr <jk@...econstruct.com.au>,
	Matt Johnston <matt@...econstruct.com.au>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Sudeep Holla <sudeep.holla@....com>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	Huisong Li <lihuisong@...wei.com>
Subject: Re: [PATCH v14 1/1] mctp pcc: Implement MCTP over PCC Transport

On Tue, Jan 14, 2025 at 02:31:11PM -0500, admiyo@...amperecomputing.com wrote:
> From: Adam Young <admiyo@...amperecomputing.com>
> 
> Implementation of network driver for
> Management Control Transport Protocol(MCTP) over
> Platform Communication Channel(PCC)
> 
> DMTF DSP:0292
> https://www.dmtf.org/sites/default/files/standards/documents/DSP0292_1.0.0WIP50.pdf
> 
> MCTP devices are specified via ACPI by entries
> in DSDT/SDST and reference channels specified
> in the PCCT.
> 
> Communication with other devices use the PCC based
> doorbell mechanism.
> 
> Signed-off-by: Adam Young <admiyo@...amperecomputing.com>

...

> +static int mctp_pcc_driver_add(struct acpi_device *acpi_dev)
> +{
> +	struct mctp_pcc_lookup_context context = {0, 0, 0};
> +	struct mctp_pcc_ndev *mctp_pcc_ndev;
> +	struct device *dev = &acpi_dev->dev;
> +	struct net_device *ndev;
> +	acpi_handle dev_handle;
> +	acpi_status status;
> +	int mctp_pcc_mtu;
> +	char name[32];
> +	int rc;
> +
> +	dev_dbg(dev, "Adding mctp_pcc device for HID %s\n",
> +		acpi_device_hid(acpi_dev));
> +	dev_handle = acpi_device_handle(acpi_dev);
> +	status = acpi_walk_resources(dev_handle, "_CRS", lookup_pcct_indices,
> +				     &context);
> +	if (!ACPI_SUCCESS(status)) {
> +		dev_err(dev, "FAILURE to lookup PCC indexes from CRS\n");
> +		return -EINVAL;
> +	}
> +
> +	//inbox initialization
> +	snprintf(name, sizeof(name), "mctpipcc%d", context.inbox_index);
> +	ndev = alloc_netdev(sizeof(struct mctp_pcc_ndev), name, NET_NAME_ENUM,
> +			    mctp_pcc_setup);
> +	if (!ndev)
> +		return -ENOMEM;
> +
> +	mctp_pcc_ndev = netdev_priv(ndev);
> +	spin_lock_init(&mctp_pcc_ndev->lock);
> +
> +	rc = mctp_pcc_initialize_mailbox(dev, &mctp_pcc_ndev->inbox,
> +					 context.inbox_index);
> +	if (rc)
> +		goto cleanup_netdev;
> +	mctp_pcc_ndev->inbox.client.rx_callback = mctp_pcc_client_rx_callback;
> +
> +	//outbox initialization
> +	rc = mctp_pcc_initialize_mailbox(dev, &mctp_pcc_ndev->outbox,
> +					 context.outbox_index);
> +	if (rc)
> +		goto cleanup_netdev;
> +
> +	mctp_pcc_ndev->acpi_device = acpi_dev;
> +	mctp_pcc_ndev->inbox.client.dev = dev;
> +	mctp_pcc_ndev->outbox.client.dev = dev;
> +	mctp_pcc_ndev->mdev.dev = ndev;
> +	acpi_dev->driver_data = mctp_pcc_ndev;
> +
> +	/* There is no clean way to pass the MTU to the callback function
> +	 * used for registration, so set the values ahead of time.
> +	 */
> +	mctp_pcc_mtu = mctp_pcc_ndev->outbox.chan->shmem_size -
> +		sizeof(struct mctp_pcc_hdr);
> +	ndev->mtu = MCTP_MIN_MTU;
> +	ndev->max_mtu = mctp_pcc_mtu;
> +	ndev->min_mtu = MCTP_MIN_MTU;
> +
> +	/* ndev needs to be freed before the iomemory (mapped above) gets
> +	 * unmapped,  devm resources get freed in reverse to the order they
> +	 * are added.
> +	 */
> +	rc = mctp_register_netdev(ndev, &mctp_netdev_ops, MCTP_PHYS_BINDING_PCC);
> +	if (rc)
> +		goto cleanup_netdev;
> +	rc = devm_add_action_or_reset(dev, mctp_cleanup_netdev, ndev);
> +	if (rc)
> +		goto cleanup_netdev;
> +return rc;


nit: the line above should be indented by one tab.

> +cleanup_netdev:
> +	free_netdev(ndev);
> +	return rc;
> +}

...