[PATCH net 7/7] sfc: support pio mapping based on cxl
From: <hidden>
Date: 2026-07-01 10:41:43
Subsystem:
networking drivers, sfc network driver, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Edward Cree, Linus Torvalds
From: Alejandro Lucero <redacted> A PIO buffer is a region of device memory to which the driver can write a packet for TX, with the device handling the transmit doorbell without requiring a DMA for getting the packet data, which helps reducing latency in certain exchanges. With CXL mem protocol this latency can be lowered further. With a device supporting CXL and successfully initialised, use the cxl region to map the memory range and use this mapping for PIO buffers. Signed-off-by: Alejandro Lucero <redacted> Reviewed-by: Dave Jiang <dave.jiang@intel.com> Acked-by: Edward Cree <ecree.xilinx@gmail.com> Link: https://patch.msgid.link/20260630151346.31201-6-alejandro.lucero-palau@amd.com Signed-off-by: Dave Jiang <dave.jiang@intel.com> --- drivers/net/ethernet/sfc/ef10.c | 41 ++++++++++++++++++++++----- drivers/net/ethernet/sfc/efx_cxl.c | 1 + drivers/net/ethernet/sfc/net_driver.h | 2 ++ drivers/net/ethernet/sfc/nic.h | 3 ++ 4 files changed, 40 insertions(+), 7 deletions(-)
diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c
index 7e04f115bbaa..73bc064929f6 100644
--- a/drivers/net/ethernet/sfc/ef10.c
+++ b/drivers/net/ethernet/sfc/ef10.c@@ -24,6 +24,7 @@ #include <linux/wait.h> #include <linux/workqueue.h> #include <net/udp_tunnel.h> +#include "efx_cxl.h" /* Hardware control for EF10 architecture including 'Huntington'. */
@@ -106,7 +107,7 @@ static int efx_ef10_get_vf_index(struct efx_nic *efx) static int efx_ef10_init_datapath_caps(struct efx_nic *efx) { - MCDI_DECLARE_BUF(outbuf, MC_CMD_GET_CAPABILITIES_V4_OUT_LEN); + MCDI_DECLARE_BUF(outbuf, MC_CMD_GET_CAPABILITIES_V7_OUT_LEN); struct efx_ef10_nic_data *nic_data = efx->nic_data; size_t outlen; int rc;
@@ -177,6 +178,12 @@ static int efx_ef10_init_datapath_caps(struct efx_nic *efx) efx->num_mac_stats); } + if (outlen < MC_CMD_GET_CAPABILITIES_V7_OUT_LEN) + nic_data->datapath_caps3 = 0; + else + nic_data->datapath_caps3 = MCDI_DWORD(outbuf, + GET_CAPABILITIES_V7_OUT_FLAGS3); + return 0; }
@@ -1140,6 +1147,9 @@ static int efx_ef10_dimension_resources(struct efx_nic *efx) unsigned int channel_vis, pio_write_vi_base, max_vis; struct efx_ef10_nic_data *nic_data = efx->nic_data; unsigned int uc_mem_map_size, wc_mem_map_size; +#ifdef CONFIG_SFC_CXL + struct efx_probe_data *probe_data; +#endif void __iomem *membase; int rc;
@@ -1263,8 +1273,23 @@ static int efx_ef10_dimension_resources(struct efx_nic *efx) iounmap(efx->membase); efx->membase = membase; - /* Set up the WC mapping if needed */ - if (wc_mem_map_size) { + if (!wc_mem_map_size) + goto skip_pio; + + /* Set up the WC mapping */ + +#ifdef CONFIG_SFC_CXL + probe_data = container_of(efx, struct efx_probe_data, efx); + if ((nic_data->datapath_caps3 & + (1 << MC_CMD_GET_CAPABILITIES_V7_OUT_CXL_CONFIG_ENABLE_LBN)) && + probe_data->cxl_pio_initialised) { + /* Using PIO through CXL mapping */ + nic_data->pio_write_base = probe_data->cxl->ctpio_cxl; + nic_data->pio_write_vi_base = pio_write_vi_base; + } else +#endif + { + /* Using legacy PIO BAR mapping */ nic_data->wc_membase = ioremap_wc(efx->membase_phys + uc_mem_map_size, wc_mem_map_size);
@@ -1279,12 +1304,14 @@ static int efx_ef10_dimension_resources(struct efx_nic *efx) nic_data->wc_membase + (pio_write_vi_base * efx->vi_stride + ER_DZ_TX_PIOBUF - uc_mem_map_size); - - rc = efx_ef10_link_piobufs(efx); - if (rc) - efx_ef10_free_piobufs(efx); } + rc = efx_ef10_link_piobufs(efx); + if (rc) + efx_ef10_free_piobufs(efx); + +skip_pio: + netif_dbg(efx, probe, efx->net_dev, "memory BAR at %pa (virtual %p+%x UC, %p+%x WC)\n", &efx->membase_phys, efx->membase, uc_mem_map_size,
diff --git a/drivers/net/ethernet/sfc/efx_cxl.c b/drivers/net/ethernet/sfc/efx_cxl.c
index 3e7c950f83e9..348d7404cd7a 100644
--- a/drivers/net/ethernet/sfc/efx_cxl.c
+++ b/drivers/net/ethernet/sfc/efx_cxl.c@@ -88,6 +88,7 @@ int efx_cxl_init(struct efx_probe_data *probe_data) return -ENOMEM; } + probe_data->cxl_pio_initialised = true; probe_data->cxl = cxl; return 0;
diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index 563e6a6e85f1..3964b2c56609 100644
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h@@ -1206,12 +1206,14 @@ struct efx_cxl; * @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 };
diff --git a/drivers/net/ethernet/sfc/nic.h b/drivers/net/ethernet/sfc/nic.h
index ec3b2df43b68..7480f9995dfb 100644
--- a/drivers/net/ethernet/sfc/nic.h
+++ b/drivers/net/ethernet/sfc/nic.h@@ -152,6 +152,8 @@ enum { * %MC_CMD_GET_CAPABILITIES response) * @datapath_caps2: Further Capabilities of datapath firmware (FLAGS2 field of * %MC_CMD_GET_CAPABILITIES response) + * @datapath_caps3: Further Capabilities of datapath firmware (FLAGS3 field of + * %MC_CMD_GET_CAPABILITIES response) * @rx_dpcpu_fw_id: Firmware ID of the RxDPCPU * @tx_dpcpu_fw_id: Firmware ID of the TxDPCPU * @must_probe_vswitching: Flag: vswitching has yet to be setup after MC reboot
@@ -187,6 +189,7 @@ struct efx_ef10_nic_data { bool must_check_datapath_caps; u32 datapath_caps; u32 datapath_caps2; + u32 datapath_caps3; unsigned int rx_dpcpu_fw_id; unsigned int tx_dpcpu_fw_id; bool must_probe_vswitching;
--
2.34.1