PCI: Add driver for a 'pci-host-ecam-generic' host controller

QEMU emulates such a device with '-machine virt,highmem=off' on ARM.
The 'highmem=off' part is required for things to work as the PCI code
in U-Boot doesn't seem to support 64-bit BARs.

Signed-off-by: Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

drivers/pci/Kconfig

@@ -33,6 +33,14 @@ config PCI_PNP
 	help
 	  Enable PCI memory and I/O space resource allocation and assignment.
 
+config PCIE_ECAM_GENERIC
+	bool "Generic ECAM-based PCI host controller support"
+	default n
+	depends on DM_PCI
+	help
+	  Say Y here if you want to enable support for generic ECAM-based
+	  PCIe host controllers, such as the one emulated by QEMU.
+
 config PCIE_DW_MVEBU
 	bool "Enable Armada-8K PCIe driver (DesignWare core)"
 	depends on DM_PCI

drivers/pci/Makefile

@@ -17,6 +17,7 @@ obj-$(CONFIG_PCI) += pci.o pci_auto_old.o
 endif
 obj-$(CONFIG_PCI) += pci_auto_common.o pci_common.o
 
+obj-$(CONFIG_PCIE_ECAM_GENERIC) += pcie_ecam_generic.o
 obj-$(CONFIG_FSL_PCI_INIT) += fsl_pci_init.o
 obj-$(CONFIG_PCI_INDIRECT_BRIDGE) += pci_indirect.o
 obj-$(CONFIG_PCI_GT64120) += pci_gt64120.o

drivers/pci/pcie_ecam_generic.c

+/*
+ * Generic PCIE host provided by e.g. QEMU
+ *
+ * Heavily based on drivers/pci/pcie_xilinx.c
+ *
+ * Copyright (C) 2016 Imagination Technologies
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <pci.h>
+
+#include <asm/io.h>
+
+/**
+ * struct generic_ecam_pcie - generic_ecam PCIe controller state
+ * @cfg_base: The base address of memory mapped configuration space
+ */
+struct generic_ecam_pcie {
+	void *cfg_base;
+};
+
+/**
+ * pci_generic_ecam_conf_address() - Calculate the address of a config access
+ * @bus: Pointer to the PCI bus
+ * @bdf: Identifies the PCIe device to access
+ * @offset: The offset into the device's configuration space
+ * @paddress: Pointer to the pointer to write the calculates address to
+ *
+ * Calculates the address that should be accessed to perform a PCIe
+ * configuration space access for a given device identified by the PCIe
+ * controller device @pcie and the bus, device & function numbers in @bdf. If
+ * access to the device is not valid then the function will return an error
+ * code. Otherwise the address to access will be written to the pointer pointed
+ * to by @paddress.
+ */
+static int pci_generic_ecam_conf_address(struct udevice *bus, pci_dev_t bdf,
+					    uint offset, void **paddress)
+{
+	struct generic_ecam_pcie *pcie = dev_get_priv(bus);
+	void *addr;
+
+	addr = pcie->cfg_base;
+	addr += PCI_BUS(bdf) << 20;
+	addr += PCI_DEV(bdf) << 15;
+	addr += PCI_FUNC(bdf) << 12;
+	addr += offset;
+	*paddress = addr;
+
+	return 0;
+}
+
+/**
+ * pci_generic_ecam_read_config() - Read from configuration space
+ * @bus: Pointer to the PCI bus
+ * @bdf: Identifies the PCIe device to access
+ * @offset: The offset into the device's configuration space
+ * @valuep: A pointer at which to store the read value
+ * @size: Indicates the size of access to perform
+ *
+ * Read a value of size @size from offset @offset within the configuration
+ * space of the device identified by the bus, device & function numbers in @bdf
+ * on the PCI bus @bus.
+ */
+static int pci_generic_ecam_read_config(struct udevice *bus, pci_dev_t bdf,
+				   uint offset, ulong *valuep,
+				   enum pci_size_t size)
+{
+	return pci_generic_mmap_read_config(bus, pci_generic_ecam_conf_address,
+					    bdf, offset, valuep, size);
+}
+
+/**
+ * pci_generic_ecam_write_config() - Write to configuration space
+ * @bus: Pointer to the PCI bus
+ * @bdf: Identifies the PCIe device to access
+ * @offset: The offset into the device's configuration space
+ * @value: The value to write
+ * @size: Indicates the size of access to perform
+ *
+ * Write the value @value of size @size from offset @offset within the
+ * configuration space of the device identified by the bus, device & function
+ * numbers in @bdf on the PCI bus @bus.
+ */
+static int pci_generic_ecam_write_config(struct udevice *bus, pci_dev_t bdf,
+				    uint offset, ulong value,
+				    enum pci_size_t size)
+{
+	return pci_generic_mmap_write_config(bus, pci_generic_ecam_conf_address,
+					     bdf, offset, value, size);
+}
+
+/**
+ * pci_generic_ecam_ofdata_to_platdata() - Translate from DT to device state
+ * @dev: A pointer to the device being operated on
+ *
+ * Translate relevant data from the device tree pertaining to device @dev into
+ * state that the driver will later make use of. This state is stored in the
+ * device's private data structure.
+ *
+ * Return: 0 on success, else -EINVAL
+ */
+static int pci_generic_ecam_ofdata_to_platdata(struct udevice *dev)
+{
+	struct generic_ecam_pcie *pcie = dev_get_priv(dev);
+	struct fdt_resource reg_res;
+	DECLARE_GLOBAL_DATA_PTR;
+	int err;
+
+	err = fdt_get_resource(gd->fdt_blob, dev_of_offset(dev), "reg",
+			       0, &reg_res);
+	if (err < 0) {
+		pr_err("\"reg\" resource not found\n");
+		return err;
+	}
+
+	pcie->cfg_base = map_physmem(reg_res.start,
+				     fdt_resource_size(&reg_res),
+				     MAP_NOCACHE);
+
+	return 0;
+}
+
+static const struct dm_pci_ops pci_generic_ecam_ops = {
+	.read_config	= pci_generic_ecam_read_config,
+	.write_config	= pci_generic_ecam_write_config,
+};
+
+static const struct udevice_id pci_generic_ecam_ids[] = {
+	{ .compatible = "pci-host-ecam-generic" },
+	{ }
+};
+
+U_BOOT_DRIVER(pci_generic_ecam) = {
+	.name			= "pci_generic_ecam",
+	.id			= UCLASS_PCI,
+	.of_match		= pci_generic_ecam_ids,
+	.ops			= &pci_generic_ecam_ops,
+	.ofdata_to_platdata	= pci_generic_ecam_ofdata_to_platdata,
+	.priv_auto_alloc_size	= sizeof(struct generic_ecam_pcie),
+};