amdblocks/biosram: Force use of abstraction

Hide the fundamental BIOSRAM accessors to force use of the
memory space via abstraction functions.

Change-Id: I774b6640cdd9873f52e446c4ca41b7c537a87883
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37862
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Richard Spiegel <richard.spiegel@silverbackltd.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

1 files changed, 48 insertions, 2 deletions

diff --git a/src/soc/amd/common/block/acpimmio/biosram.c b/src/soc/amd/common/block/acpimmio/biosram.c
index e33f02d02c..814fdf3b00 100644
--- a/src/soc/amd/common/block/acpimmio/biosram.c
+++ b/src/soc/amd/common/block/acpimmio/biosram.c
@@ -11,9 +11,55 @@
  * GNU General Public License for more details.
  */
 
-#include <cbmem.h>
-#include <amdblocks/acpimmio.h>
+#include <amdblocks/acpimmio_map.h>
 #include <amdblocks/biosram.h>
+#include <cbmem.h>
+#include <device/mmio.h>
+#include <stdint.h>
+
+/* BiosRam Ranges at 0xfed80500 or I/O 0xcd4/0xcd5 */
+#define BIOSRAM_AP_ENTRY		0xe8 /* 8 bytes */
+#define BIOSRAM_CBMEM_TOP		0xf0 /* 4 bytes */
+#define BIOSRAM_UMA_SIZE		0xf4 /* 4 bytes */
+#define BIOSRAM_UMA_BASE		0xf8 /* 8 bytes */
+
+static uint8_t biosram_read8(uint8_t reg)
+{
+	return read8((void *)(ACPIMMIO_BIOSRAM_BASE + reg));
+}
+
+static void biosram_write8(uint8_t reg, uint8_t value)
+{
+	write8((void *)(ACPIMMIO_BIOSRAM_BASE + reg), value);
+}
+
+static uint16_t biosram_read16(uint8_t reg) /* Must be 1 byte at a time */
+{
+	return (biosram_read8(reg + sizeof(uint8_t)) << 8 | biosram_read8(reg));
+}
+
+static uint32_t biosram_read32(uint8_t reg)
+{
+	uint32_t value = biosram_read16(reg + sizeof(uint16_t)) << 16;
+	return value | biosram_read16(reg);
+}
+
+static void biosram_write16(uint8_t reg, uint16_t value)
+{
+	biosram_write8(reg, value & 0xff);
+	value >>= 8;
+	biosram_write8(reg + sizeof(uint8_t), value & 0xff);
+}
+
+static void biosram_write32(uint8_t reg, uint32_t value)
+{
+	biosram_write16(reg, value & 0xffff);
+	value >>= 16;
+	biosram_write16(reg + sizeof(uint16_t), value & 0xffff);
+}
+
+
+/* Access to BIOSRAM is only allowed through the abstractions below. */
 
 void *get_ap_entry_ptr(void)
 {