[PATCH v19 05/22] sfc: add cxl support

alejandro.lucero-palau
2025-10-06T10:03:23Z

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>
---
drivers/net/ethernet/sfc/Kconfig | 9 +++++
drivers/net/ethernet/sfc/Makefile | 1 +
drivers/net/ethernet/sfc/efx.c | 15 ++++++-
drivers/net/ethernet/sfc/efx_cxl.c | 56 +++++++++++++++++++++++++++
drivers/net/ethernet/sfc/efx_cxl.h | 40 +++++++++++++++++++
drivers/net/ethernet/sfc/net_driver.h | 10 +++++
6 files changed, 130 insertions(+), 1 deletion(-)
create mode 100644 drivers/net/ethernet/sfc/efx_cxl.c
create mode 100644 drivers/net/ethernet/sfc/efx_cxl.h

diff --git a/drivers/net/ethernet/sfc/Kconfig b/drivers/net/ethernet/sfc/Kconfig
index c4c43434f314..979f2801e2a8 100644
--- a/drivers/net/ethernet/sfc/Kconfig
+++ b/drivers/net/ethernet/sfc/Kconfig
@@ -66,6 +66,15 @@ config SFC_MCDI_LOGGING
Driver-Interface) commands and responses, allowing debugging of
driver/firmware interaction. The tracing is actually enabled by
a sysfs file 'mcdi_logging' under the PCI device.
+config SFC_CXL
+ bool "Solarflare SFC9100-family CXL support"
+ depends on SFC && CXL_BUS >= SFC
+ default SFC
+ help
+ This enables SFC CXL support if the kernel is configuring CXL for
+ using CTPIO with CXL.mem. The SFC device with CXL support and
+ with a CXL-aware firmware can be used for minimizing latencies
+ when sending through CTPIO.

source "drivers/net/ethernet/sfc/falcon/Kconfig"
source "drivers/net/ethernet/sfc/siena/Kconfig"
diff --git a/drivers/net/ethernet/sfc/Makefile b/drivers/net/ethernet/sfc/Makefile
index d99039ec468d..bb0f1891cde6 100644
--- a/drivers/net/ethernet/sfc/Makefile
+++ b/drivers/net/ethernet/sfc/Makefile
@@ -13,6 +13,7 @@ sfc-$(CONFIG_SFC_SRIOV) += sriov.o ef10_sriov.o ef100_sriov.o ef100_rep.o \
mae.o tc.o tc_bindings.o tc_counters.o \
tc_encap_actions.o tc_conntrack.o

+sfc-$(CONFIG_SFC_CXL) += efx_cxl.o
obj-$(CONFIG_SFC) += sfc.o

obj-$(CONFIG_SFC_FALCON) += falcon/
diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index 112e55b98ed3..537668278375 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -34,6 +34,7 @@
#include "selftest.h"
#include "sriov.h"
#include "efx_devlink.h"
+#include "efx_cxl.h"

#include "mcdi_port_common.h"
#include "mcdi_pcol.h"
@@ -981,12 +982,15 @@ static void efx_pci_remove(struct pci_dev *pci_dev)
efx_pci_remove_main(efx);

efx_fini_io(efx);
+
+ probe_data = container_of(efx, struct efx_probe_data, efx);
+ efx_cxl_exit(probe_data);
+
pci_dbg(efx->pci_dev, "shutdown successful\n");

efx_fini_devlink_and_unlock(efx);
efx_fini_struct(efx);
free_netdev(efx->net_dev);
- probe_data = container_of(efx, struct efx_probe_data, efx);
kfree(probe_data);
};

@@ -1190,6 +1194,15 @@ static int efx_pci_probe(struct pci_dev *pci_dev,
if (rc)
goto fail2;

+ /* A successful cxl initialization implies a CXL region created to be
+ * used for PIO buffers. If there is no CXL support, or initialization
+ * fails, efx_cxl_pio_initialised will be false and legacy PIO buffers
+ * defined at specific PCI BAR regions will be used.
+ */
+ rc = efx_cxl_init(probe_data);
+ if (rc)
+ pci_err(pci_dev, "CXL initialization failed with error %d\n", rc);
+
rc = efx_pci_probe_post_io(efx);
if (rc) {
/* On failure, retry once immediately.
diff --git a/drivers/net/ethernet/sfc/efx_cxl.c b/drivers/net/ethernet/sfc/efx_cxl.c
new file mode 100644
index 000000000000..8e0481d8dced
--- /dev/null
+++ b/drivers/net/ethernet/sfc/efx_cxl.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/****************************************************************************
+ *
+ * Driver for AMD network controllers and boards
+ * Copyright (C) 2025, Advanced Micro Devices, Inc.
+ */
+
+#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_err(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_dev->dev.id, dvsec, struct efx_cxl,
+ cxlds, false);
+
+ if (!cxl)
+ return -ENOMEM;
+
+ probe_data->cxl = cxl;
+
+ return 0;
+}
+
+void efx_cxl_exit(struct efx_probe_data *probe_data)
+{
+}
+
+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..961639cef692
--- /dev/null
+++ b/drivers/net/ethernet/sfc/efx_cxl.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/****************************************************************************
+ * Driver for AMD network controllers and boards
+ * Copyright (C) 2025, Advanced Micro Devices, Inc.
+ *
+ * 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 cxl_root_decoder;
+struct cxl_port;
+struct cxl_endpoint_decoder;
+struct cxl_region;
+struct efx_probe_data;
+
+struct efx_cxl {
+ struct cxl_dev_state cxlds;
+ struct cxl_memdev *cxlmd;
+ struct cxl_root_decoder *cxlrd;
+ struct cxl_port *endpoint;
+ struct cxl_endpoint_decoder *cxled;
+ struct cxl_region *efx_region;
+ void __iomem *ctpio_cxl;
+};
+
+int efx_cxl_init(struct efx_probe_data *probe_data);
+void efx_cxl_exit(struct efx_probe_data *probe_data);
+#else
+static inline int efx_cxl_init(struct efx_probe_data *probe_data) { return 0; }
+static inline void efx_cxl_exit(struct efx_probe_data *probe_data) {}
+#endif
+#endif
diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index 5c0f306fb019..0e685b8a9980 100644
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -1199,14 +1199,24 @@ 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.
*/
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)
--
2.34.1