PCI: Add pci_find_ht_capability() for finding Hypertransport capabilities

There are already several places in the kernel that want to search a PCI
device for a given Hypertransport capability. Although this is possible
using pci_find_capability() etc., it makes sense to encapsulate that
logic in a helper - pci_find_ht_capability().

To cater for searching exhaustively for a capability, we also provide
pci_find_next_ht_capability().

We also need to cater for the fact that the HT capability fields may be
either 3 or 5 bits wide. pci_find_ht_capability() deals with this for you,
but callers using the #defines directly must handle that themselves.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 11 insertions, 1 deletions

diff --git a/include/linux/pci_regs.h b/include/linux/pci_regs.h
index 064b1dc71c22..a54b48f7cee2 100644
--- a/include/linux/pci_regs.h
+++ b/include/linux/pci_regs.h
@@ -475,9 +475,19 @@
 #define PCI_PWR_CAP             12      /* Capability */
 #define  PCI_PWR_CAP_BUDGET(x)  ((x) & 1)       /* Included in system budget */
 
-/* Hypertransport sub capability types */
+/*
+ * Hypertransport sub capability types
+ *
+ * Unfortunately there are both 3 bit and 5 bit capability types defined
+ * in the HT spec, catering for that is a little messy. You probably don't
+ * want to use these directly, just use pci_find_ht_capability() and it
+ * will do the right thing for you.
+ */
+#define HT_3BIT_CAP_MASK        0xE0
 #define HT_CAPTYPE_SLAVE        0x00    /* Slave/Primary link configuration */
 #define HT_CAPTYPE_HOST         0x20    /* Host/Secondary link configuration */
+
+#define HT_5BIT_CAP_MASK        0xF8
 #define HT_CAPTYPE_IRQ          0x80    /* IRQ Configuration */
 #define HT_CAPTYPE_REMAPPING_40 0xA0    /* 40 bit address remapping */
 #define HT_CAPTYPE_REMAPPING_64 0xA2    /* 64 bit address remapping */