Re: [PATCH v26 1/8] sfc: add cxl support

[Alejandro Lucero Palau <alucerop@amd.com>]

On 4/29/26 22:14, Cheatham, Benjamin wrote:
> On 4/23/2026 1:05 PM, alejandro.lucero-palau@amd.com wrote:
>> From: Alejandro Lucero <alucerop@amd.com>
>>
>> Add CXL initialization based on new CXL API for accel drivers and make
>> it dependent on kernel CXL configuration.
>>
>> Signed-off-by: Alejandro Lucero <alucerop@amd.com>
>> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>> Acked-by: Edward Cree <ecree.xilinx@gmail.com>
>> Reviewed-by: Alison Schofield <alison.schofield@intel.com>
>> Reviewed-by: Dan Williams <dan.j.williams@intel.com>
>> Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> Code looks good, just some notes on the copyright notices and a tiny nit. With the copyright fixed:
>
> Reviewed-by: Ben Cheatham <benjamin.cheatham@amd.com>


Thanks.  I'll fix those minor issues.


>
> [snip]
>
>> diff --git a/drivers/net/ethernet/sfc/efx_cxl.c b/drivers/net/ethernet/sfc/efx_cxl.c
>> new file mode 100644
>> index 000000000000..b7e8d85a43d3
>> --- /dev/null
>> +++ b/drivers/net/ethernet/sfc/efx_cxl.c
>> @@ -0,0 +1,52 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/****************************************************************************
>> + *
>> + * Driver for AMD network controllers and boards
>> + * Copyright (C) 2025, Advanced Micro Devices, Inc.
> I'm not a lawyer, but I'm pretty sure the year needs to be 2026 here.
>> + */
>> +
>> +#include <linux/pci.h>
>> +
>> +#include "net_driver.h"
>> +#include "efx_cxl.h"
>> +
>> +#define EFX_CTPIO_BUFFER_SIZE	SZ_256M
>> +
>> +int efx_cxl_init(struct efx_probe_data *probe_data)
>> +{
>> +	struct efx_nic *efx = &probe_data->efx;
>> +	struct pci_dev *pci_dev = efx->pci_dev;
>> +	struct efx_cxl *cxl;
>> +	u16 dvsec;
>> +
>> +	probe_data->cxl_pio_initialised = false;
>> +
>> +	/* Is the device configured with and using CXL? */
>> +	if (!pcie_is_cxl(pci_dev))
>> +		return 0;
>> +
>> +	dvsec = pci_find_dvsec_capability(pci_dev, PCI_VENDOR_ID_CXL,
>> +					  PCI_DVSEC_CXL_DEVICE);
>> +	if (!dvsec) {
>> +		pci_info(pci_dev, "CXL_DVSEC_PCIE_DEVICE capability not found\n");
>> +		return 0;
>> +	}
>> +
>> +	pci_dbg(pci_dev, "CXL_DVSEC_PCIE_DEVICE capability found\n");
>> +
>> +	/* Create a cxl_dev_state embedded in the cxl struct using cxl core api
>> +	 * specifying no mbox available.
>> +	 */
>> +	cxl = devm_cxl_dev_state_create(&pci_dev->dev, CXL_DEVTYPE_DEVMEM,
>> +					pci_get_dsn(pci_dev), dvsec,
>> +					struct efx_cxl, cxlds, false);
>> +
>> +	if (!cxl)
>> +		return -ENOMEM;
>> +
>> +	probe_data->cxl = cxl;
>> +
>> +	return 0;
>> +}
>> +
>> +MODULE_IMPORT_NS("CXL");
>> diff --git a/drivers/net/ethernet/sfc/efx_cxl.h b/drivers/net/ethernet/sfc/efx_cxl.h
>> new file mode 100644
>> index 000000000000..04e46278464d
>> --- /dev/null
>> +++ b/drivers/net/ethernet/sfc/efx_cxl.h
>> @@ -0,0 +1,29 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/****************************************************************************
>> + * Driver for AMD network controllers and boards
>> + * Copyright (C) 2025, Advanced Micro Devices, Inc.
> Same thing here.
>
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms of the GNU General Public License version 2 as published
>> + * by the Free Software Foundation, incorporated herein by reference.
>> + */
>> +
>> +#ifndef EFX_CXL_H
>> +#define EFX_CXL_H
>> +
>> +#ifdef CONFIG_SFC_CXL
>> +
>> +#include <cxl/cxl.h>
>> +
>> +struct efx_probe_data;
>> +
>> +struct efx_cxl {
>> +	struct cxl_dev_state cxlds;
>> +	struct cxl_memdev *cxlmd;
>> +};
>> +
>> +int efx_cxl_init(struct efx_probe_data *probe_data);
>> +#else
>> +static inline int efx_cxl_init(struct efx_probe_data *probe_data) { return 0; }
>> +#endif
>> +#endif
>> diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
>> index b98c259f672d..3964b2c56609 100644
>> --- a/drivers/net/ethernet/sfc/net_driver.h
>> +++ b/drivers/net/ethernet/sfc/net_driver.h
>> @@ -1197,14 +1197,24 @@ struct efx_nic {
>>   	atomic_t n_rx_noskb_drops;
>>   };
>>   
>> +#ifdef CONFIG_SFC_CXL
>> +struct efx_cxl;
>> +#endif
>> +
>>   /**
>>    * struct efx_probe_data - State after hardware probe
>>    * @pci_dev: The PCI device
>>    * @efx: Efx NIC details
>> + * @cxl: details of related cxl objects
>> + * @cxl_pio_initialised: cxl initialization outcome.
> Tiny nit: The description of the variable should use the english spelling as well (i.e. initialisation).
>
>>    */
>>   struct efx_probe_data {
>>   	struct pci_dev *pci_dev;
>>   	struct efx_nic efx;
>> +#ifdef CONFIG_SFC_CXL
>> +	struct efx_cxl *cxl;
>> +	bool cxl_pio_initialised;
>> +#endif
>>   };
>>   
>>   static inline struct efx_nic *efx_netdev_priv(struct net_device *dev)