amd/stoneyridge: Convert BiosRam access to MMIO

Change the BiosRam read/write functions to use the fixed MMIO range at
0xfed80500.  This is faster than two accesses per byte when using I/O
0xcd4/0xcd5.

Note that BiosRam may only be accessed byte-by-byte.  It does not decode
normally.

Change-Id: I9d8baf2bd5d9d48a87bddfb6a0b86e292a8fdf7d
Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Reviewed-on: https://review.coreboot.org/23436
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

1 files changed, 3 insertions, 4 deletions

diff --git a/src/soc/amd/stoneyridge/sb_util.c b/src/soc/amd/stoneyridge/sb_util.c
index 5238506199..a98a334fe2 100644
--- a/src/soc/amd/stoneyridge/sb_util.c
+++ b/src/soc/amd/stoneyridge/sb_util.c
@@ -78,16 +78,15 @@ void smi_write8(uint8_t offset, uint8_t value)
 
 uint8_t biosram_read8(uint8_t offset)
 {
-	outb(offset, BIOSRAM_INDEX);
-	return inb(BIOSRAM_DATA);
+	return read8((void *)(BIOSRAM_MMIO_BASE + offset));
 }
 
 void biosram_write8(uint8_t offset, uint8_t value)
 {
-	outb(offset, BIOSRAM_INDEX);
-	outb(value, BIOSRAM_DATA);
+	write8((void *)(BIOSRAM_MMIO_BASE + offset), value);
 }
 
+/* BiosRam may only be accessed a byte at a time */
 uint16_t biosram_read16(uint8_t offset)
 {
 	int i;