MIPS: PCI: Introduce CONFIG_PCI_DRIVERS_LEGACY

Introduce 2 Kconfig symbols, CONFIG_PCI_DRIVERS_GENERIC &
CONFIG_PCI_DRIVERS_LEGACY, which indicate whether the system should be
built to for PCI drivers using the MIPS-specific struct pci_controller
API (hereafter "legacy" drivers) or more generic drivers using only
functionality provided by the PCI core (hereafter "generic" drivers).

The Kconfig entries are created such that platforms have to select
CONFIG_PCI_DRIVERS_GENERIC if they wish to use it - that is, the default
is CONFIG_PCI_DRIVERS_LEGACY so that existing platforms need no
modification.

The functions declared in pci.h are rearranged with those provided only
by pci-legacy.c being guarded by an #ifdef CONFIG_PCI_DRIVERS_LEGACY to
ensure they are only used in configurations where they are implemented.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14345/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 7a75215..d31f839 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -2974,7 +2974,6 @@
 	bool "Support for PCI controller"
 	depends on HW_HAS_PCI
 	select PCI_DOMAINS
-	select NO_GENERIC_PCI_IOPORT_MAP
 	help
 	  Find out whether you have a PCI motherboard. PCI is the name of a
 	  bus system, i.e. the way the CPU talks to the other stuff inside
@@ -2998,6 +2997,13 @@
 config PCI_DOMAINS_GENERIC
 	bool
 
+config PCI_DRIVERS_GENERIC
+	bool
+
+config PCI_DRIVERS_LEGACY
+	def_bool !PCI_DRIVERS_GENERIC
+	select NO_GENERIC_PCI_IOPORT_MAP
+
 source "drivers/pci/Kconfig"
 
 #