amd/stoneyridge: Add BIOS RAM R/W functions

The internal FCH contains 256 bytes of "BiosRam" that maintains its
state until RSMRST# is asserted or standby power is lost.  Add functions
to support read and write operations.

Change-Id: I2ddf58a63e69b2775de9a8163534b13dad2ea2fe
Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Reviewed-on: https://review.coreboot.org/22724
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Richard Spiegel <richard.spiegel@silverbackltd.com>

2 files changed, 51 insertions, 0 deletions

diff --git a/src/soc/amd/stoneyridge/include/soc/southbridge.h b/src/soc/amd/stoneyridge/include/soc/southbridge.h
index 73e9b6fcd5..9f91b505c7 100644
--- a/src/soc/amd/stoneyridge/include/soc/southbridge.h
+++ b/src/soc/amd/stoneyridge/include/soc/southbridge.h
@@ -329,6 +329,12 @@ uint32_t smi_read32(uint8_t offset);
 void smi_write8(uint8_t offset, uint8_t value);
 void smi_write16(uint8_t offset, uint16_t value);
 void smi_write32(uint8_t offset, uint32_t value);
+uint8_t biosram_read8(uint8_t offset);
+void biosram_write8(uint8_t offset, uint8_t value);
+uint16_t biosram_read16(uint8_t offset);
+void biosram_write16(uint8_t offset, uint16_t value);
+uint32_t biosram_read32(uint8_t offset);
+void biosram_write32(uint8_t offset, uint32_t value);
 uint16_t pm_acpi_pm_cnt_blk(void);
 uint16_t pm_acpi_pm_evt_blk(void);
 void xhci_pm_write8(uint8_t reg, uint8_t value);
diff --git a/src/soc/amd/stoneyridge/sb_util.c b/src/soc/amd/stoneyridge/sb_util.c
index e394432d4a..5238506199 100644
--- a/src/soc/amd/stoneyridge/sb_util.c
+++ b/src/soc/amd/stoneyridge/sb_util.c
@@ -76,6 +76,51 @@ void smi_write8(uint8_t offset, uint8_t value)
 	write8((void *)(APU_SMI_BASE + offset), value);
 }
 
+uint8_t biosram_read8(uint8_t offset)
+{
+	outb(offset, BIOSRAM_INDEX);
+	return inb(BIOSRAM_DATA);
+}
+
+void biosram_write8(uint8_t offset, uint8_t value)
+{
+	outb(offset, BIOSRAM_INDEX);
+	outb(value, BIOSRAM_DATA);
+}
+
+uint16_t biosram_read16(uint8_t offset)
+{
+	int i;
+	uint16_t value = 0;
+	for (i = sizeof(value) - 1 ; i >= 0 ; i--)
+		value = (value << 8) | biosram_read8(offset + i);
+	return value;
+}
+
+uint32_t biosram_read32(uint8_t offset)
+{
+	uint32_t value = biosram_read16(offset + sizeof(uint16_t)) << 16;
+	return value | biosram_read16(offset);
+}
+
+void biosram_write16(uint8_t offset, uint16_t value)
+{
+	int i;
+	for (i = 0 ; i < sizeof(value) ; i++) {
+		biosram_write8(offset + i, value & 0xff);
+		value >>= 8;
+	}
+}
+
+void biosram_write32(uint8_t offset, uint32_t value)
+{
+	int i;
+	for (i = 0 ; i < sizeof(value) ; i++) {
+		biosram_write8(offset + i, value & 0xff);
+		value >>= 8;
+	}
+}
+
 uint16_t pm_acpi_pm_cnt_blk(void)
 {
 	return pm_read16(PM1_CNT_BLK);