linux-kernel - [RFC PATCH 04/25] PCI: endpoint: Add inbound mapping ops to EPC core

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Message-ID: <20251023071916.901355-5-den@valinux.co.jp>
Date: Thu, 23 Oct 2025 16:18:55 +0900
From: Koichiro Den <den@...inux.co.jp>
To: ntb@...ts.linux.dev,
	linux-pci@...r.kernel.org,
	dmaengine@...r.kernel.org,
	linux-kernel@...r.kernel.org
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Subject: [RFC PATCH 04/25] PCI: endpoint: Add inbound mapping ops to EPC core

Add new EPC ops map_inbound() and unmap_inbound() for mapping a subrange
of a BAR into CPU space. These will be implemented by controller drivers
such as DesignWare.

Signed-off-by: Koichiro Den <den@...inux.co.jp>
---
 drivers/pci/endpoint/pci-epc-core.c | 44 +++++++++++++++++++++++++++++
 include/linux/pci-epc.h             | 11 ++++++++
 2 files changed, 55 insertions(+)

diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index ca7f19cc973a..825109e54ba9 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -444,6 +444,50 @@ int pci_epc_map_addr(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 }
 EXPORT_SYMBOL_GPL(pci_epc_map_addr);
 
+/**
+ * pci_epc_map_inbound() - map a BAR subrange to the local CPU address
+ * @epc: the EPC device on which BAR has to be configured
+ * @func_no: the physical endpoint function number in the EPC device
+ * @vfunc_no: the virtual endpoint function number in the physical function
+ * @epf_bar: the struct epf_bar that contains the BAR information
+ * @offset: byte offset from the BAR base selected by the host
+ *
+ * Invoke to configure the BAR of the endpoint device and map a subrange
+ * selected by @offset to a CPU address.
+ *
+ * Returns 0 on success, -EOPNOTSUPP if unsupported, or a negative errno.
+ */
+int pci_epc_map_inbound(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
+			struct pci_epf_bar *epf_bar, u64 offset)
+{
+	if (!epc || !epc->ops || !epc->ops->map_inbound)
+		return -EOPNOTSUPP;
+
+	return epc->ops->map_inbound(epc, func_no, vfunc_no, epf_bar, offset);
+}
+EXPORT_SYMBOL_GPL(pci_epc_map_inbound);
+
+/**
+ * pci_epc_unmap_inbound() - unmap a previously mapped BAR subrange
+ * @epc: the EPC device on which the inbound mapping was programmed
+ * @func_no: the physical endpoint function number in the EPC device
+ * @vfunc_no: the virtual endpoint function number in the physical function
+ * @epf_bar: the struct epf_bar used when the mapping was created
+ * @offset: byte offset from the BAR base that was mapped
+ *
+ * Invoke to remove a BAR subrange mapping created by pci_epc_map_inbound().
+ * If the controller has no support, this call is a no-op.
+ */
+void pci_epc_unmap_inbound(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
+			   struct pci_epf_bar *epf_bar, u64 offset)
+{
+	if (!epc || !epc->ops || !epc->ops->unmap_inbound)
+		return;
+
+	epc->ops->unmap_inbound(epc, func_no, vfunc_no, epf_bar, offset);
+}
+EXPORT_SYMBOL_GPL(pci_epc_unmap_inbound);
+
 /**
  * pci_epc_mem_map() - allocate and map a PCI address to a CPU address
  * @epc: the EPC device on which the CPU address is to be allocated and mapped
diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index 4286bfdbfdfa..a5fb91cc2982 100644
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -71,6 +71,8 @@ struct pci_epc_map {
  *		region
  * @map_addr: ops to map CPU address to PCI address
  * @unmap_addr: ops to unmap CPU address and PCI address
+ * @map_inbound: ops to map a subrange inside a BAR to CPU address.
+ * @unmap_inbound: ops to unmap a subrange inside a BAR and CPU address.
  * @set_msi: ops to set the requested number of MSI interrupts in the MSI
  *	     capability register
  * @get_msi: ops to get the number of MSI interrupts allocated by the RC from
@@ -99,6 +101,10 @@ struct pci_epc_ops {
 			    phys_addr_t addr, u64 pci_addr, size_t size);
 	void	(*unmap_addr)(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 			      phys_addr_t addr);
+	int	(*map_inbound)(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
+			       struct pci_epf_bar *epf_bar, u64 offset);
+	void	(*unmap_inbound)(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
+				 struct pci_epf_bar *epf_bar, u64 offset);
 	int	(*set_msi)(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 			   u8 nr_irqs);
 	int	(*get_msi)(struct pci_epc *epc, u8 func_no, u8 vfunc_no);
@@ -286,6 +292,11 @@ int pci_epc_map_addr(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 		     u64 pci_addr, size_t size);
 void pci_epc_unmap_addr(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 			phys_addr_t phys_addr);
+
+int pci_epc_map_inbound(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
+			struct pci_epf_bar *epf_bar, u64 offset);
+void pci_epc_unmap_inbound(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
+			   struct pci_epf_bar *epf_bar, u64 offset);
 int pci_epc_set_msi(struct pci_epc *epc, u8 func_no, u8 vfunc_no, u8 nr_irqs);
 int pci_epc_get_msi(struct pci_epc *epc, u8 func_no, u8 vfunc_no);
 int pci_epc_set_msix(struct pci_epc *epc, u8 func_no, u8 vfunc_no, u16 nr_irqs,
-- 
2.48.1