[PATCH net 6/7] sfc: obtain and map cxl range using devm_cxl_probe_mem

[<alejandro.lucero-palau@amd.com>]

From: Alejandro Lucero <alucerop@amd.com>

Use core API for safely obtain the CXL range linked to an HDM committed
by the BIOS. Map such a range for being used as the ctpio buffer.

A potential user space action through sysfs unbinding or core cxl
modules remove will trigger sfc driver device detachment, with that case
not racing with this mapping as this is done during driver probe and
therefore protected with device lock against those user space actions.

Signed-off-by: Alejandro Lucero <alucerop@amd.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Acked-by: Edward Cree <ecree.xilinx@gmail.com>
Signed-off-by: Dan Williams <djbw@kernel.org>
Link: https://patch.msgid.link/20260630151346.31201-5-alejandro.lucero-palau@amd.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 drivers/net/ethernet/sfc/efx.c     |  2 ++
 drivers/net/ethernet/sfc/efx_cxl.c | 23 +++++++++++++++++++++++
 drivers/net/ethernet/sfc/efx_cxl.h |  3 +++
 3 files changed, 28 insertions(+)

diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index 61cbb6cfc360..3806cd3dd7f4 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -984,6 +984,7 @@ static void efx_pci_remove(struct pci_dev *pci_dev)
 	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");
 
@@ -1242,6 +1243,7 @@ static int efx_pci_probe(struct pci_dev *pci_dev,
 	return 0;
 
  fail3:
+	efx_cxl_exit(probe_data);
 	efx_fini_io(efx);
  fail2:
 	efx_fini_struct(efx);
diff --git a/drivers/net/ethernet/sfc/efx_cxl.c b/drivers/net/ethernet/sfc/efx_cxl.c
index 18b535b3ea40..3e7c950f83e9 100644
--- a/drivers/net/ethernet/sfc/efx_cxl.c
+++ b/drivers/net/ethernet/sfc/efx_cxl.c
@@ -18,6 +18,7 @@ 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 range cxl_pio_range;
 	struct efx_cxl *cxl;
 	u16 dvsec;
 	int rc;
@@ -73,9 +74,31 @@ int efx_cxl_init(struct efx_probe_data *probe_data)
 		return -ENODEV;
 	}
 
+	cxl->cxlmd = devm_cxl_probe_mem(&cxl->cxlds, &cxl_pio_range);
+	if (IS_ERR(cxl->cxlmd)) {
+		pci_err(pci_dev, "CXL accel memdev creation failed\n");
+		return PTR_ERR(cxl->cxlmd);
+	}
+
+	cxl->ctpio_cxl = ioremap_wc(cxl_pio_range.start,
+				    range_len(&cxl_pio_range));
+	if (!cxl->ctpio_cxl) {
+		pci_err(pci_dev, "CXL ioremap region (%pra) failed\n",
+			&cxl_pio_range);
+		return -ENOMEM;
+	}
+
 	probe_data->cxl = cxl;
 
 	return 0;
 }
 
+void efx_cxl_exit(struct efx_probe_data *probe_data)
+{
+	if (!probe_data->cxl)
+		return;
+
+	iounmap(probe_data->cxl->ctpio_cxl);
+}
+
 MODULE_IMPORT_NS("CXL");
diff --git a/drivers/net/ethernet/sfc/efx_cxl.h b/drivers/net/ethernet/sfc/efx_cxl.h
index 04e46278464d..3e2705cb063f 100644
--- a/drivers/net/ethernet/sfc/efx_cxl.h
+++ b/drivers/net/ethernet/sfc/efx_cxl.h
@@ -20,10 +20,13 @@ struct efx_probe_data;
 struct efx_cxl {
 	struct cxl_dev_state cxlds;
 	struct cxl_memdev *cxlmd;
+	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
-- 
2.34.1