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PCI: Add pci_find_ht_capability() for finding Hypertransport capabilities

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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>
This commit is contained in:
Michael Ellerman
2006-11-22 18:26:18 +11:00
committed by Greg Kroah-Hartman
parent d3bac118fb
commit 687d5fe3dc
3 changed files with 94 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/pci/pci.c
+81 -3
View File
@@ -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 pci_bus *bus, unsigned int devfn, u8 pos,
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_dev *dev, int cap)
}
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