Separate out ram shadow code and permit more code to write to bios.

Extract shadow code from rombios32.c to its own file - shadow.c.
Reorg post.c so that shadow enable happens early and ram lock happens
    late in boot process.
Also, improve some comments in post.c and reorg code slightly.

1 files changed, 87 insertions, 0 deletions

diff --git a/src/shadow.c b/src/shadow.c
new file mode 100644
index 00000000..6500029c
--- /dev/null
+++ b/src/shadow.c
@@ -0,0 +1,87 @@
+// Support for enabling/disabling BIOS ram shadowing.
+//
+// Copyright (C) 2008  Kevin O'Connor <kevin@koconnor.net>
+// Copyright (C) 2006 Fabrice Bellard
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include "util.h" // memcpy
+#include "pci.h" // pci_config_writeb
+
+#define BIOS_TMP_STORAGE  0x30000 /* 64 KB used to copy the BIOS to shadow RAM */
+
+// Test if 'addr' is in the range from 'start'..'start+size'
+#define IN_RANGE(addr, start, size) ({   \
+            u32 __addr = (addr);         \
+            u32 __start = (start);       \
+            u32 __size = (size);         \
+            (__addr - __start < __size); \
+        })
+
+// Enable shadowing and copy bios.
+static void
+copy_bios(PCIDevice d)
+{
+    int v = pci_config_readb(d, 0x59);
+    v |= 0x30;
+    pci_config_writeb(d, 0x59, v);
+    memcpy((void *)0x000f0000, (void *)BIOS_TMP_STORAGE, 0x10000);
+}
+
+// Make the BIOS code segment area (0xf0000) writable.
+void
+make_bios_writable()
+{
+    if (CONFIG_COREBOOT)
+        return;
+
+    dprintf(3, "enabling shadow ram\n");
+
+    // Locate chip controlling ram shadowing.
+    PCIDevice d;
+    int ret = pci_find_device(0x8086, 0x1237, 0, &d);
+    if (ret) {
+        dprintf(1, "Unable to unlock ram - bridge not found\n");
+        return;
+    }
+
+    // Copy the bios to a temporary area.
+    memcpy((void *)BIOS_TMP_STORAGE, (void *)0x000f0000, 0x10000);
+
+    // Enable shadowing and copy bios.
+    if (IN_RANGE((u32)copy_bios, 0xf0000, 0x10000)) {
+        // Jump to shadow enable function - use the copy in the
+        // temporary storage area so that memory does not change under
+        // the executing code.
+        u32 pos = (u32)copy_bios - 0xf0000 + BIOS_TMP_STORAGE;
+        void (*func)(PCIDevice) = (void*)pos;
+        func(d);
+    } else {
+        copy_bios(d);
+    }
+
+    // Clear the temporary area.
+    memset((void *)BIOS_TMP_STORAGE, 0, 0x10000);
+}
+
+// Make the BIOS code segment area (0xf0000) read-only.
+void
+make_bios_readonly()
+{
+    if (CONFIG_COREBOOT)
+        return;
+
+    dprintf(3, "locking shadow ram\n");
+
+    PCIDevice d;
+    int ret = pci_find_device(0x8086, 0x1237, 0, &d);
+    if (ret) {
+        dprintf(1, "Unable to lock ram - bridge not found\n");
+        return;
+    }
+
+    wbinvd();
+    int v = pci_config_readb(d, 0x59);
+    v = (v & 0x0f) | (0x10);
+    pci_config_writeb(d, 0x59, v);
+}