bcma: prepare Kconfig symbol for PCI driver

Driver for PCIe core requires PCI to be enabled, however we shouldn't
require it for the whole bus. Someone may be not interested in extra
PCI devices and what's more there are SoCs without any PCI at all (like
BCM5356C0, BCM5357*, BCM47186B0). For more details see Kconfig "help".
Please note this patch doesn't allow disabling PCI drivers yet, as it
requires more work on calls to bcma_core_pci_* functions.

Signed-off-by: Rafał Miłecki <[e-mail]>
Signed-off-by: Kalle Valo <[e-mail]>

drivers/bcma/Kconfig

···
 config BCMA_HOST_PCI
 	bool "Support for BCMA on PCI-host bus"
 	depends on BCMA_HOST_PCI_POSSIBLE
+	select BCMA_DRIVER_PCI
 	default y
 
 config BCMA_DRIVER_PCI_HOSTMODE
···
 	  BCM47XX line.
 
 	  If unsure, say N
+
+# TODO: make it depend on PCI when ready
+config BCMA_DRIVER_PCI
+	bool
+	default y
+	help
+	  BCMA bus may have many versions of PCIe core. This driver
+	  supports:
+	  1) PCIe core working in clientmode
+	  2) PCIe Gen 2 clientmode core
+
+	  In general PCIe (Gen 2) clientmode core is required on PCIe
+	  hosted buses. It's responsible for initialization and basic
+	  hardware management.
+	  This driver is also prerequisite for a hostmode PCIe core
+	  support.
 
 config BCMA_DRIVER_MIPS
 	bool "BCMA Broadcom MIPS core driver"

drivers/bcma/Makefile

···
 bcma-y					+= driver_chipcommon_b.o
 bcma-$(CONFIG_BCMA_SFLASH)		+= driver_chipcommon_sflash.o
 bcma-$(CONFIG_BCMA_NFLASH)		+= driver_chipcommon_nflash.o
-bcma-y					+= driver_pci.o
-bcma-y					+= driver_pcie2.o
+bcma-$(CONFIG_BCMA_DRIVER_PCI)		+= driver_pci.o
+bcma-$(CONFIG_BCMA_DRIVER_PCI)		+= driver_pcie2.o
 bcma-$(CONFIG_BCMA_DRIVER_PCI_HOSTMODE)	+= driver_pci_host.o
 bcma-$(CONFIG_BCMA_DRIVER_MIPS)		+= driver_mips.o
 bcma-$(CONFIG_BCMA_DRIVER_GMAC_CMN)	+= driver_gmac_cmn.o