pcie: endpoint: Introduce API to achieve PCIe data transfer

Introduce common API to achieve data transfer using memcpy
to/from outbound region of PCIe EP.

Signed-off-by: Abhishek Shah <abhishek.shah@broadcom.com>

drivers/pcie/endpoint/CMakeLists.txt

@@ -1 +1,3 @@
 # SPDX-License-Identifier: Apache-2.0
+
+zephyr_sources(pcie_ep_common.c)

drivers/pcie/endpoint/pcie_ep_common.c

@@ -0,0 +1,110 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Copyright 2020 Broadcom
+ *
+ */
+
+#include <drivers/pcie/endpoint/pcie_ep.h>
+#include <string.h>
+#include <sys/util.h>
+
+static int pcie_ep_mapped_copy(uint64_t mapped_addr, uintptr_t local_addr,
+			       const uint32_t size,
+			       const enum xfer_direction dir)
+{
+	/*
+	 * Make sure that address can be generated by core, this condition
+	 * would not hit if proper pcie_ob_mem_type is passed by core
+	 */
+	if ((!IS_ENABLED(CONFIG_64BIT)) && (mapped_addr >> 32)) {
+		return -EINVAL;
+	}
+
+	if (dir == DEVICE_TO_HOST) {
+		memcpy(UINT_TO_POINTER(mapped_addr),
+		       UINT_TO_POINTER(local_addr), size);
+	} else {
+		memcpy(UINT_TO_POINTER(local_addr),
+		       UINT_TO_POINTER(mapped_addr), size);
+	}
+
+	return 0;
+}
+
+/*
+ * Helper API to achieve data transfer with memcpy operation
+ * through PCIe outbound memory
+ */
+int pcie_ep_xfer_data_memcpy(struct device *dev, uint64_t pcie_addr,
+			     uintptr_t *local_addr, uint32_t size,
+			     enum pcie_ob_mem_type ob_mem_type,
+			     enum xfer_direction dir)
+{
+	uint64_t mapped_addr;
+	int mapped_size, ret;
+	uint32_t xfer_size, unmapped_size;
+
+	mapped_size = pcie_ep_map_addr(dev, pcie_addr, &mapped_addr,
+				       size, ob_mem_type);
+
+	/* Check if outbound memory mapping succeeded */
+	if (mapped_size < 0) {
+		return mapped_size;
+	}
+
+	ret = pcie_ep_mapped_copy(mapped_addr, (uintptr_t)local_addr,
+				  mapped_size, dir);
+
+	pcie_ep_unmap_addr(dev, mapped_addr);
+
+	/* Check if mapped_copy succeeded */
+	if (ret < 0) {
+		return ret;
+	}
+
+	/* Check if we achieved data transfer for given size */
+	if (mapped_size == size) {
+		return 0;
+	}
+
+	/*
+	 * In normal case, we are done with data transfer by now,
+	 * but some PCIe address translation hardware requires us to
+	 * align Host address to be mapped to the translation window size.
+	 * So, even though translation window size is good enough for
+	 * size of Host buffer, we may not be able to map entire Host buffer
+	 * to given outbound window in one time, and we may need to map
+	 * ramaining size and complete remaining data transfer
+	 */
+
+	xfer_size = mapped_size; /* save already tranferred data size */
+
+	unmapped_size = size - mapped_size;
+	mapped_size = pcie_ep_map_addr(dev, pcie_addr + xfer_size,
+				       &mapped_addr, unmapped_size,
+				       ob_mem_type);
+
+	/* Check if outbound memory mapping succeeded */
+	if (mapped_size < 0) {
+		return mapped_size;
+	}
+
+	ret = pcie_ep_mapped_copy(mapped_addr,
+				  ((uintptr_t)local_addr) + xfer_size,
+				  mapped_size, dir);
+
+	pcie_ep_unmap_addr(dev, mapped_addr);
+
+	/* Check if mapped_copy succeeded */
+	if (ret < 0) {
+		return ret;
+	}
+
+	/* In second attempt, we must have completed data transfer */
+	if (mapped_size != unmapped_size) {
+		return -EIO;
+	}
+
+	return 0;
+}

include/drivers/pcie/endpoint/pcie_ep.h

@@ -30,6 +30,11 @@ enum pci_ep_irq_type {
 	PCIE_EP_IRQ_MSIX,	/**< Raise MSIX interrupt */
 };
 
+enum xfer_direction {
+	HOST_TO_DEVICE,		/**< Read from Host */
+	DEVICE_TO_HOST,		/**< Write to Host */
+};
+
 struct pcie_ep_driver_api {
 	int (*conf_read)(struct device *dev, uint32_t offset, uint32_t *data);
 	void (*conf_write)(struct device *dev, uint32_t offset, uint32_t data);
@@ -160,4 +165,15 @@ static inline int pcie_ep_raise_irq(struct device *dev,
 	return api->raise_irq(dev, irq_type, irq_num);
 }
 
+/**
+ * @brief Data transfer using memcpy
+ *
+ * @details Helper API to achieve data transfer with memcpy
+ *          through PCIe outbound memory
+ */
+int pcie_ep_xfer_data_memcpy(struct device *dev, uint64_t pcie_addr,
+			     uintptr_t *local_addr, uint32_t size,
+			     enum pcie_ob_mem_type ob_mem_type,
+			     enum xfer_direction dir);
+
 #endif /* ZEPHYR_INCLUDE_DRIVERS_PCIE_EP_H_ */