1 files changed, 32 insertions, 0 deletions

diff --git a/include/linux/cs5535.h b/include/linux/cs5535.h
index 39e93e8ed95d..eb34108a608b 100644
--- a/include/linux/cs5535.h
+++ b/include/linux/cs5535.h
@@ -36,6 +36,38 @@
 #define LBAR_ACPI_SIZE          0x40
 #define LBAR_PMS_SIZE           0x80
 
+/* VSA2 magic values */
+#define VSA_VRC_INDEX           0xAC1C
+#define VSA_VRC_DATA            0xAC1E
+#define VSA_VR_UNLOCK           0xFC53  /* unlock virtual register */
+#define VSA_VR_SIGNATURE        0x0003
+#define VSA_VR_MEM_SIZE         0x0200
+#define AMD_VSA_SIG             0x4132  /* signature is ascii 'VSA2' */
+#define GSW_VSA_SIG             0x534d  /* General Software signature */
+
+#include <linux/io.h>
+
+static inline int cs5535_has_vsa2(void)
+{
+        static int has_vsa2 = -1;
+
+        if (has_vsa2 == -1) {
+                uint16_t val;
+
+                /*
+                 * The VSA has virtual registers that we can query for a
+                 * signature.
+                 */
+                outw(VSA_VR_UNLOCK, VSA_VRC_INDEX);
+                outw(VSA_VR_SIGNATURE, VSA_VRC_INDEX);
+
+                val = inw(VSA_VRC_DATA);
+                has_vsa2 = (val == AMD_VSA_SIG || val == GSW_VSA_SIG);
+        }
+
+        return has_vsa2;
+}
+
 /* GPIOs */
 #define GPIO_OUTPUT_VAL         0x00
 #define GPIO_OUTPUT_ENABLE      0x04