[PATCH v2 1/5] PCI: endpoint: Add DMA auxiliary resource metadata

[Koichiro Den <den@valinux.co.jp>]

Endpoint functions that export controller-local DMA channels need the
controller register and descriptor-memory layout.

Add DMA control and descriptor-memory resource types. The control resource
carries the register layout and channel counts. Each descriptor region is
associated with the static channel ID assigned by the local DMA driver.

Signed-off-by: Koichiro Den <den@valinux.co.jp>
---
Changes in v2:
  - Rework PCI DMA EPF v7 patch 3 with only the metadata needed by vNTB.
    https://lore.kernel.org/r/20260813063757.3131865-4-den@valinux.co.jp/
  - Keep descriptor metadata keyed only by static channel IDs. (Frank)
    https://lore.kernel.org/r/lm7tadnxsyrypu4mypptlkx5qkytex4qxsijdr5ydud2n3anvf@yakjfjg5ng4u/

 include/linux/pci-epc.h | 34 +++++++++++++++++++++++++++++++---
 1 file changed, 31 insertions(+), 3 deletions(-)

diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index f247cf9bcf1a..e0348e7bc534 100644
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -65,6 +65,8 @@ struct pci_epc_map {
  * enum pci_epc_aux_resource_type - auxiliary resource type identifiers
  * @PCI_EPC_AUX_DOORBELL_MMIO: Doorbell MMIO, that might be outside the DMA
  *                             controller register window
+ * @PCI_EPC_AUX_DMA_CTRL_MMIO: DMA controller MMIO register window
+ * @PCI_EPC_AUX_DMA_DESC_MEM: DMA descriptor memory
  *
  * EPC backends may expose auxiliary blocks (e.g. DMA engines) by mapping their
  * register windows and descriptor memories into BAR space. This enum
@@ -72,13 +74,25 @@ struct pci_epc_map {
  */
 enum pci_epc_aux_resource_type {
 	PCI_EPC_AUX_DOORBELL_MMIO,
+	PCI_EPC_AUX_DMA_CTRL_MMIO,
+	PCI_EPC_AUX_DMA_DESC_MEM,
 };
 
 /**
- * struct pci_epc_aux_resource - a physical auxiliary resource that may be
- *                               exposed for peer use
+ * enum pci_epc_aux_dma_reg_layout - DMA controller register layout
+ * @PCI_EPC_AUX_DMA_REG_LAYOUT_UNKNOWN: unknown or uninitialized layout
+ * @PCI_EPC_AUX_DMA_REG_LAYOUT_DW_EDMA: Synopsys DesignWare eDMA/HDMA layout
+ */
+enum pci_epc_aux_dma_reg_layout {
+	PCI_EPC_AUX_DMA_REG_LAYOUT_UNKNOWN = 0,
+	PCI_EPC_AUX_DMA_REG_LAYOUT_DW_EDMA,
+};
+
+/**
+ * struct pci_epc_aux_resource - an auxiliary resource that may be exposed for
+ *                               peer use
  * @type:       resource type, see enum pci_epc_aux_resource_type
- * @phys_addr:  physical base address of the resource
+ * @phys_addr:  CPU physical base address of an MMIO resource
  * @size:       size of the resource in bytes
  * @bar:        BAR number where this resource is already exposed to the RC
  *              (NO_BAR if not)
@@ -99,6 +113,20 @@ struct pci_epc_aux_resource {
 			int irq; /* IRQ number for the doorbell handler */
 			u32 data; /* write value to ring the doorbell */
 		} db_mmio;
+
+		/* PCI_EPC_AUX_DMA_CTRL_MMIO */
+		struct {
+			enum pci_epc_aux_dma_reg_layout reg_layout;
+			u32 reg_layout_data;
+			u16 ep_to_rc_ch_cnt;
+			u16 rc_to_ep_ch_cnt;
+		} dma_ctrl;
+
+		/* PCI_EPC_AUX_DMA_DESC_MEM */
+		struct {
+			dma_addr_t dma_addr; /* Endpoint-local DMA address */
+			u16 chan_id;
+		} dma_desc;
 	} u;
 };
 
-- 
2.51.0