haswell: always use MMIO PCI config accesses

Add a bootblock.c file for the northbridge and setup the
PCIEXBAR as the first thing using IO PCI config acceses.
After that all PCI config accesses can use MMIO.

Change-Id: I51d229c626c45705dda1757c2f14265cbc0e6183
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/2617
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/src/northbridge/intel/haswell/bootblock.c b/src/northbridge/intel/haswell/bootblock.c
new file mode 100644
index 0000000000..35f357f57f
--- /dev/null
+++ b/src/northbridge/intel/haswell/bootblock.c
@@ -0,0 +1,27 @@
+#include <arch/io.h>
+#include <arch/romcc_io.h>
+
+/* Just re-define this instead of including haswell.h. It blows up romcc. */
+#define PCIEXBAR	0x60
+
+static void bootblock_northbridge_init(void)
+{
+	uint32_t reg;
+
+	/*
+	 * The "io" variant of the config access is explicitly used to
+	 * setup the PCIEXBAR because CONFIG_MMCONF_SUPPORT_DEFAULT is set to
+	 * to true. That way all subsequent non-explicit config accesses use
+	 * MCFG. This code also assumes that bootblock_northbridge_init() is
+	 * the first thing called in the non-asm boot block code. The final
+	 * assumption is that no assembly code is using the
+	 * CONFIG_MMCONF_SUPPORT_DEFAULT option to do PCI config acceses.
+	 *
+	 * The PCIEXBAR is assumed to live in the memory mapped IO space under
+	 * 4GiB.
+	 */
+	reg = 0;
+	pci_io_write_config32(PCI_DEV(0,0,0), PCIEXBAR + 4, reg);
+	reg = CONFIG_MMCONF_BASE_ADDRESS | 4 | 1; /* 64MiB - 0-63 buses. */
+	pci_io_write_config32(PCI_DEV(0,0,0), PCIEXBAR, reg);
+}