lspci: Decode Null Capability

The PCI Code and ID Assignment spec, r1.9, sec 2, defines a "Null
Capability" containing no registers other than the 8-bit Capability ID
(00h) and an 8-bit Next Capability Pointer.

Some devices, e.g., the Intel [8086:2058] implement this Capability.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

3 files changed, 8 insertions, 0 deletions

diff --git a/lib/header.h b/lib/header.h
index 0b12b2c..1f0e460 100644
--- a/lib/header.h
+++ b/lib/header.h
@@ -185,6 +185,7 @@
 /* Capability lists */
 
 #define PCI_CAP_LIST_ID		0	/* Capability ID */
+#define  PCI_CAP_ID_NULL	0x00	/* Null Capability */
 #define  PCI_CAP_ID_PM		0x01	/* Power Management */
 #define  PCI_CAP_ID_AGP		0x02	/* Accelerated Graphics Port */
 #define  PCI_CAP_ID_VPD		0x03	/* Vital Product Data */
@@ -211,6 +212,7 @@
 
 /* Capabilities residing in the PCI Express extended configuration space */
 
+#define PCI_EXT_CAP_ID_NULL	0x00	/* Null Capability */
 #define PCI_EXT_CAP_ID_AER	0x01	/* Advanced Error Reporting */
 #define PCI_EXT_CAP_ID_VC	0x02	/* Virtual Channel */
 #define PCI_EXT_CAP_ID_DSN	0x03	/* Device Serial Number */
diff --git a/ls-caps.c b/ls-caps.c
index bc7829c..8b707c2 100644
--- a/ls-caps.c
+++ b/ls-caps.c
@@ -1536,6 +1536,9 @@ show_caps(struct device *d, int where)
 	    }
 	  switch (id)
 	    {
+	    case PCI_CAP_ID_NULL:
+	      printf("Null\n");
+	      break;
 	    case PCI_CAP_ID_PM:
 	      cap_pm(d, where, cap);
 	      break;
diff --git a/ls-ecaps.c b/ls-ecaps.c
index cb3d46d..3f6a364 100644
--- a/ls-ecaps.c
+++ b/ls-ecaps.c
@@ -737,6 +737,9 @@ show_ext_caps(struct device *d, int type)
 	}
       switch (id)
 	{
+	  case PCI_EXT_CAP_ID_NULL:
+	    printf("Null\n");
+	    break;
 	  case PCI_EXT_CAP_ID_AER:
 	    cap_aer(d, where, type);
 	    break;