pci: Add helper to find a VPD resource data type

This patch adds the pci_vpd_find_tag() helper function to find VPD
resource data types in a buffer.

Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
Signed-off-by: Michael Chan <mchan@broadcom.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 43 insertions, 0 deletions

diff --git a/drivers/pci/vpd.c b/drivers/pci/vpd.c
new file mode 100644
index 000000000000..6bc554576f8d
--- /dev/null
+++ b/drivers/pci/vpd.c
@@ -0,0 +1,43 @@
+/*
+ * File:        vpd.c
+ * Purpose:     Provide PCI VPD support
+ *
+ * Copyright (C) 2010 Broadcom Corporation.
+ */
+
+#include <linux/pci.h>
+
+int pci_vpd_find_tag(const u8 *buf, unsigned int off, unsigned int len, u8 rdt)
+{
+        int i;
+
+        for (i = off; i < len; ) {
+                u8 val = buf[i];
+
+                if (val & PCI_VPD_LRDT) {
+                        /* Don't return success of the tag isn't complete */
+                        if (i + PCI_VPD_LRDT_TAG_SIZE > len)
+                                break;
+
+                        if (val == rdt)
+                                return i;
+
+                        i += PCI_VPD_LRDT_TAG_SIZE +
+                             pci_vpd_lrdt_size(&buf[i]);
+                } else {
+                        u8 tag = val & ~PCI_VPD_SRDT_LEN_MASK;
+
+                        if (tag == rdt)
+                                return i;
+
+                        if (tag == PCI_VPD_SRDT_END)
+                                break;
+
+                        i += PCI_VPD_SRDT_TAG_SIZE +
+                             pci_vpd_srdt_size(&buf[i]);
+                }
+        }
+
+        return -ENOENT;
+}
+EXPORT_SYMBOL_GPL(pci_vpd_find_tag);