[DM/Feature] Basic PCI/PCIe (Peripheral Component Interconnect Express) bus

PCI/PCIe have better performance and more devices support, such as
NVMe, GPU, Powerful NIC (Like RDMA). PCI/PCIe can access control by
IOMMU that the virtualiztion and userspace driver will more safety.
PCI/PCIe device could hot plugging, no design modifications SoC required,
PCI/PCIe on Embedded SoC is popular now.
We make a simple framework to support them.

Feature Lists:
1.PCI INTx: the INT[A-D] pin IRQ for legacy PCI, work with platform PIC.
2.MSI/MSI-X: the message write IRQ for PCIe, work with platform's PIC.
3.PME: we only support the D0, D1, D2, D3HOT, D3COLD init by framework.
4.Endpoint: a simple EP framework for PCI FPGA or NTB function.
5.OFW: we only support work on OFW SoC, ACPI support in the future maybe.

Host controller:
1. Common PCI host controller on ECAM.
2. Generic PCI host controller on ECAM.

Signed-off-by: GuEe-GUI <2991707448@qq.com>

components/drivers/pci/SConscript

@@ -0,0 +1,28 @@
+from building import *
+
+objs = []
+
+if not GetDepend(['RT_USING_PCI']):
+    Return('objs')
+
+cwd     = GetCurrentDir()
+list    = os.listdir(cwd)
+CPPPATH = [cwd + '/../include']
+
+src = ['access.c', 'host-bridge.c', 'irq.c', 'pci.c', 'pme.c', 'probe.c']
+
+if GetDepend(['RT_USING_OFW']):
+    src += ['ofw.c']
+
+if GetDepend(['RT_PCI_ECAM']):
+    src += ['ecam.c']
+
+group = DefineGroup('DeviceDrivers', src, depend = [''], CPPPATH = CPPPATH)
+
+for d in list:
+    path = os.path.join(cwd, d)
+    if os.path.isfile(os.path.join(path, 'SConscript')):
+        objs = objs + SConscript(os.path.join(d, 'SConscript'))
+objs = objs + group
+
+Return('objs')