amd/pi: Make BottomIo position configurable

Some PCI peripherals, such as FPGA accelerators, require a great amount
of memory mapped IO. This patch allows the user to select at build time
the bottom IO to leave enough space for such devices.

We cannot calculate this value at runtime because it has to be set
before the PCI devices are enumerated.

Change-Id: Ic590e8aa8b91ff89877cbff6afd10614d33dcf8d
Credit-to: Kyösti Mälkki <kyosti.malkki@gmail.com>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Reviewed-on: https://review.coreboot.org/17980
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>

src/northbridge/amd/pi/Kconfig

@@ -20,6 +20,18 @@ config NORTHBRIDGE_AMD_PI
 
 if NORTHBRIDGE_AMD_PI
 
+config BOTTOMIO_POSITION
+	hex "Bottom of 32-bit IO space"
+	default 0xD0000000
+	help
+	  If PCI peripherals with big BARs are connected to the system
+	  the bottom of the IO must be decreased to allocate such
+	  devices.
+
+	  Declare the beginning of the 128MB-aligned MMIO region.  This
+	  option is useful when PCI peripherals requesting large address
+	  ranges are present.
+
 config CONSOLE_VGA_MULTI
 	bool
 	default n

src/northbridge/amd/pi/agesawrapper.c

@@ -140,7 +140,8 @@ AGESA_STATUS agesawrapper_amdinitpost(void)
 	// the compiler to flag the error if CONFIG_GFXUMA is not set.
 	PostParams->MemConfig.UmaMode = CONFIG_GFXUMA ? UMA_AUTO : UMA_NONE;
 	PostParams->MemConfig.UmaSize = 0;
-	PostParams->MemConfig.BottomIo = (UINT16)(0xD0000000 >> 24);
+	PostParams->MemConfig.BottomIo = (UINT16)
+					 (CONFIG_BOTTOMIO_POSITION >> 24);
 	status = AmdInitPost (PostParams);
 	printk(
 			BIOS_SPEW,