initial support for pflash / cbfs

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 63 insertions, 0 deletions

diff --git a/pflash.c b/pflash.c
new file mode 100644
index 0000000..950bc74
--- /dev/null
+++ b/pflash.c
@@ -0,0 +1,63 @@
+#include <stddef.h>
+#include "bios.h"
+#include "pflash.h"
+#include "stdio.h"
+
+#define CLEAR_STATUS_CMD         0x50
+#define READ_STATUS_CMD          0x70
+#define QUERY_CMD                0x98
+#define READ_ARRAY_CMD           0xff
+
+static void *pflash_detect(uint8_t *top_addr)
+{
+	volatile uint8_t *p = top_addr;
+	uint8_t save;
+	int i, blocks, sector_len;
+
+	/* The low byte of the address is part of the command, so it must be 0.  */
+	if ((uintptr_t)p & 256)
+		panic();
+
+	p -= 256;
+	for (i = 0; i < 256; i++)
+		if (p[i] != CLEAR_STATUS_CMD)
+			break;
+	if (i == 256)
+		return NULL;
+
+	save = p[i];
+	p[i] = CLEAR_STATUS_CMD;
+	if (p[i] == CLEAR_STATUS_CMD) {
+		/* behaves as RAM */
+		p[i] = save;
+		return NULL;
+	}
+	p[i] = READ_STATUS_CMD;
+	if (p[i] != 0) {
+		/* doesn't behave as flash */
+		return NULL;
+	}
+
+	/* 0x2d-0x2e: blocks_per_device - 1, little endian */
+	/* 0x2f-0x30: sector_len / 256 */
+	p[i] = QUERY_CMD;
+	blocks = p[0x2d] + (p[0x2e] << 8) + 1;
+	sector_len = (p[0x2f] + (p[0x30] << 8)) << 8;
+
+	p[i] = READ_ARRAY_CMD;
+	return top_addr - blocks * sector_len;
+}
+
+void *pflash_base(int n, size_t *size)
+{
+	uint8_t *top = NULL;
+	uint8_t *prev;
+	while (n-- >= 0) {
+		prev = top;
+		top = pflash_detect(top);
+		if (!top)
+			return NULL;
+		*size = prev - top;
+	}
+	return top;
+}