[PATCH v2 03/18] PCI: endpoint: Introduce pci_epc_mem_map()/unmap()

[Damien Le Moal <dlemoal@kernel.org>]

Introduce the function pci_epc_mem_map() to facilitate controller memory
address allocation and mapping to a RC PCI address region in endpoint
function drivers.

This function first uses pci_epc_map_align() to determine the controller
memory address alignment (offset and size) constraints. The result of
this function is used to allocate a controller physical memory region
using pci_epc_mem_alloc_addr() and map it to the RC PCI address
space with pci_epc_map_addr(). Since pci_epc_map_align() may indicate
that a mapping can be smaller than the requested size, pci_epc_mem_map()
may only partially map the RC PCI address region specified and return
a smaller size for the effective mapping.

The counterpart of pci_epc_mem_map() to unmap and free the controller
memory address region is pci_epc_mem_unmap().

Both functions operate using struct pci_epc_map data structure which is
extended to contain the physical and virtual addresses of the allocated
controller memory. Endpoint function drivers can use struct pci_epc_map
to implement read/write accesses within the mapped RC PCI address region
using the ->virt_addr and ->size fields.

This commit contains contributions from Rick Wertenbroek
<rick.wertenbroek@gmail.com>.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
---
 drivers/pci/endpoint/pci-epc-core.c | 68 +++++++++++++++++++++++++++++
 include/linux/pci-epc.h             |  6 +++
 2 files changed, 74 insertions(+)

diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index 37758ca91d7f..0095b54bdf9e 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -530,6 +530,74 @@ int pci_epc_map_addr(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 }
 EXPORT_SYMBOL_GPL(pci_epc_map_addr);
 
+/**
+ * pci_epc_mem_map() - allocate and map CPU address to PCI address
+ * @epc: the EPC device on which the CPU address is to be allocated and mapped
+ * @func_no: the physical endpoint function number in the EPC device
+ * @vfunc_no: the virtual endpoint function number in the physical function
+ * @pci_addr: PCI address to which the CPU address should be mapped
+ * @size: the number of bytes to map starting from @pci_addr
+ * @map: where to return the mapping information
+ *
+ * Allocate a controller physical address region and map it to a RC PCI address
+ * region, taking into account the controller physical address mapping
+ * constraints (if any). Returns the effective size of the mapping, which may
+ * be less than @size, or a negative error code in case of error.
+ */
+ssize_t pci_epc_mem_map(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
+			u64 pci_addr, size_t size, struct pci_epc_map *map)
+{
+	int ret;
+
+	ret = pci_epc_map_align(epc, func_no, vfunc_no, pci_addr, size, map);
+	if (ret)
+		return ret;
+
+	map->virt_base = pci_epc_mem_alloc_addr(epc, &map->phys_base,
+						map->map_size);
+	if (!map->virt_base)
+		return -ENOMEM;
+
+	map->phys_addr = map->phys_base + map->map_ofst;
+	map->virt_addr = map->virt_base + map->map_ofst;
+
+	ret = pci_epc_map_addr(epc, func_no, vfunc_no, map->phys_base,
+			       map->map_pci_addr, map->map_size);
+	if (ret) {
+		pci_epc_mem_free_addr(epc, map->phys_base, map->virt_base,
+				      map->map_size);
+		return ret;
+	}
+
+	return map->pci_size;
+}
+EXPORT_SYMBOL_GPL(pci_epc_mem_map);
+
+/**
+ * pci_epc_mem_unmap() - unmap from PCI address and free a CPU address region
+ * @epc: the EPC device on which the CPU address is allocated and mapped
+ * @func_no: the physical endpoint function number in the EPC device
+ * @vfunc_no: the virtual endpoint function number in the physical function
+ * @map: the mapping information
+ *
+ * Allocate and map local CPU address to a PCI address, accounting for the
+ * controller local CPU address alignment constraints.
+ */
+void pci_epc_mem_unmap(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
+		       struct pci_epc_map *map)
+{
+	if (!pci_epc_function_is_valid(epc, func_no, vfunc_no))
+		return;
+
+	if (!map || !map->pci_size)
+		return;
+
+	pci_epc_unmap_addr(epc, func_no, vfunc_no, map->phys_base);
+	pci_epc_mem_free_addr(epc, map->phys_base, map->virt_base,
+			      map->map_size);
+}
+EXPORT_SYMBOL_GPL(pci_epc_mem_unmap);
+
 /**
  * pci_epc_clear_bar() - reset the BAR
  * @epc: the EPC device for which the BAR has to be cleared
diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index 8cfb4aaf2628..86397a500b54 100644
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -304,4 +304,10 @@ void __iomem *pci_epc_mem_alloc_addr(struct pci_epc *epc,
 				     phys_addr_t *phys_addr, size_t size);
 void pci_epc_mem_free_addr(struct pci_epc *epc, phys_addr_t phys_addr,
 			   void __iomem *virt_addr, size_t size);
+
+ssize_t pci_epc_mem_map(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
+			u64 pci_addr, size_t size, struct pci_epc_map *map);
+void pci_epc_mem_unmap(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
+		       struct pci_epc_map *map);
+
 #endif /* __LINUX_PCI_EPC_H */
-- 
2.44.0