[openib-general] [PATCH 2/6] Add pci_find_ht_capability() for finding Hypertransport capabilities
Michael Ellerman
michael at ellerman.id.au
Tue Nov 21 23:26:18 PST 2006
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 at ellerman.id.au>
---
This version makes pci_find_ht_capability() safe against broken PCI
capability chains. pci_find_next_ht_capability() still requries the
caller to maintain a TTL if they want to be 100% safe.
---
drivers/pci/pci.c | 84 +++++++++++++++++++++++++++++++++++++++++++++--
include/linux/pci.h | 2 +
include/linux/pci_regs.h | 12 ++++++
3 files changed, 94 insertions(+), 4 deletions(-)
Index: msi/drivers/pci/pci.c
===================================================================
--- msi.orig/drivers/pci/pci.c
+++ msi/drivers/pci/pci.c
@@ -68,12 +68,14 @@ pci_max_busnr(void)
#endif /* 0 */
-static int __pci_find_next_cap(struct pci_bus *bus, unsigned int devfn, u8 pos, int cap)
+#define PCI_FIND_CAP_TTL 48
+
+static int __pci_find_next_cap_ttl(struct pci_bus *bus, unsigned int devfn,
+ u8 pos, int cap, int *ttl)
{
u8 id;
- int ttl = 48;
- while (ttl--) {
+ while ((*ttl)--) {
pci_bus_read_config_byte(bus, devfn, pos, &pos);
if (pos < 0x40)
break;
@@ -89,6 +91,14 @@ static int __pci_find_next_cap(struct pc
return 0;
}
+static int __pci_find_next_cap(struct pci_bus *bus, unsigned int devfn,
+ u8 pos, int cap)
+{
+ int ttl = PCI_FIND_CAP_TTL;
+
+ return __pci_find_next_cap_ttl(bus, devfn, pos, cap, &ttl);
+}
+
int pci_find_next_capability(struct pci_dev *dev, u8 pos, int cap)
{
return __pci_find_next_cap(dev->bus, dev->devfn,
@@ -224,6 +234,74 @@ int pci_find_ext_capability(struct pci_d
}
EXPORT_SYMBOL_GPL(pci_find_ext_capability);
+static int __pci_find_next_ht_cap(struct pci_dev *dev, int pos, int ht_cap)
+{
+ int rc, ttl = PCI_FIND_CAP_TTL;
+ u8 cap, mask;
+
+ if (ht_cap == HT_CAPTYPE_SLAVE || ht_cap == HT_CAPTYPE_HOST)
+ mask = HT_3BIT_CAP_MASK;
+ else
+ mask = HT_5BIT_CAP_MASK;
+
+ pos = __pci_find_next_cap_ttl(dev->bus, dev->devfn, pos,
+ PCI_CAP_ID_HT, &ttl);
+ while (pos) {
+ rc = pci_read_config_byte(dev, pos + 3, &cap);
+ if (rc != PCIBIOS_SUCCESSFUL)
+ return 0;
+
+ if ((cap & mask) == ht_cap)
+ return pos;
+
+ pos = __pci_find_next_cap_ttl(dev->bus, dev->devfn, pos,
+ PCI_CAP_ID_HT, &ttl);
+ }
+
+ return 0;
+}
+/**
+ * pci_find_next_ht_capability - query a device's Hypertransport capabilities
+ * @dev: PCI device to query
+ * @pos: Position from which to continue searching
+ * @ht_cap: Hypertransport capability code
+ *
+ * To be used in conjunction with pci_find_ht_capability() to search for
+ * all capabilities matching @ht_cap. @pos should always be a value returned
+ * from pci_find_ht_capability().
+ *
+ * NB. To be 100% safe against broken PCI devices, the caller should take
+ * steps to avoid an infinite loop.
+ */
+int pci_find_next_ht_capability(struct pci_dev *dev, int pos, int ht_cap)
+{
+ return __pci_find_next_ht_cap(dev, pos + PCI_CAP_LIST_NEXT, ht_cap);
+}
+EXPORT_SYMBOL_GPL(pci_find_next_ht_capability);
+
+/**
+ * pci_find_ht_capability - query a device's Hypertransport capabilities
+ * @dev: PCI device to query
+ * @ht_cap: Hypertransport capability code
+ *
+ * Tell if a device supports a given Hypertransport capability.
+ * Returns an address within the device's PCI configuration space
+ * or 0 in case the device does not support the request capability.
+ * The address points to the PCI capability, of type PCI_CAP_ID_HT,
+ * which has a Hypertransport capability matching @ht_cap.
+ */
+int pci_find_ht_capability(struct pci_dev *dev, int ht_cap)
+{
+ int pos;
+
+ pos = __pci_bus_find_cap_start(dev->bus, dev->devfn, dev->hdr_type);
+ if (pos)
+ pos = __pci_find_next_ht_cap(dev, pos, ht_cap);
+
+ return pos;
+}
+EXPORT_SYMBOL_GPL(pci_find_ht_capability);
+
/**
* pci_find_parent_resource - return resource region of parent bus of given region
* @dev: PCI device structure contains resources to be searched
Index: msi/include/linux/pci.h
===================================================================
--- msi.orig/include/linux/pci.h
+++ msi/include/linux/pci.h
@@ -453,6 +453,8 @@ struct pci_dev *pci_find_slot (unsigned
int pci_find_capability (struct pci_dev *dev, int cap);
int pci_find_next_capability (struct pci_dev *dev, u8 pos, int cap);
int pci_find_ext_capability (struct pci_dev *dev, int cap);
+int pci_find_ht_capability (struct pci_dev *dev, int ht_cap);
+int pci_find_next_ht_capability (struct pci_dev *dev, int pos, int ht_cap);
struct pci_bus *pci_find_next_bus(const struct pci_bus *from);
struct pci_dev *pci_get_device(unsigned int vendor, unsigned int device,
Index: msi/include/linux/pci_regs.h
===================================================================
--- msi.orig/include/linux/pci_regs.h
+++ msi/include/linux/pci_regs.h
@@ -468,9 +468,19 @@
#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 */
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