[SeaBIOS] [PATCH] pci: capability scanning function'
Michael S. Tsirkin
mst at redhat.com
Wed Jul 6 16:57:47 CEST 2011
On Wed, Jul 06, 2011 at 05:03:21PM +0300, Michael S. Tsirkin wrote:
> Add pci_find_capability to scan capability list.
> Return 0 on error, capability offset if found.
>
> Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
>
> ---
>
> Not useful by itself, but should be handy if
> we ever want to look at capabilities such as pci express.
Here's an example using slot register and
pci express register to figure out how many
expansion slots does a bridge have:
diff --git a/src/pci.c b/src/pci.c
index 23a6878..5e72347 100644
--- a/src/pci.c
+++ b/src/pci.c
@@ -57,30 +57,59 @@ pci_config_maskw(u16 bdf, u32 addr, u16 off, u16 on)
pci_config_writew(bdf, addr, val);
}
unsigned char pci_find_capability(u16 bdf, unsigned char cap_id)
{
unsigned char next, prev;
int loop = 0;
if (!(pci_config_readb(bdf, PCI_STATUS) & PCI_STATUS_CAP_LIST))
return 0;
for (prev = PCI_CAPABILITY_LIST; (next = pci_config_readb(bdf, prev));
prev = next + PCI_CAP_LIST_NEXT) {
if (pci_config_readb(bdf, next + PCI_CAP_LIST_ID) == cap_id)
break;
if (loop++ > 0x100) {
dprintf(1, "ERROR: capability loop detected. "
"PCI device %02x:%02x.%x\n"
, pci_bdf_to_bus(bdf), pci_bdf_to_dev(bdf)
, pci_bdf_to_fn(bdf));
return 0;
}
}
return next;
}
+static int pci_bridge_conventional_slots(u16 bdf)
+{
+ u8 cap = pci_find_capability(bdf, PCI_CAP_ID_SLOTID);
+ if (!cap)
+ return 32;
+ u8 slots = pci_config_readb(bdf, cap + 2);
+ return slots;
+}
+
+int pci_bridge_get_slots(u16 bdf)
+{
+ /* No express cap: assume 32 ports. */
+ u8 flags, type;
+ u8 cap = pci_find_capability(bdf, PCI_CAP_ID_EXP);
+ if (!cap)
+ return pci_bridge_conventional_slots(bdf);
+ flags = pci_config_readb(cap + 2);
+ type = flags >> 4;
+ switch (type) {
+ case PCI_EXP_TYPE_UPSTREAM:
+ return 0;
+ case PCI_EXP_TYPE_DOWNSTREAM:
+ return 1;
+ default:
+ return pci_bridge_conventional_slots(bdf);
+ }
+
+}
+
// Helper function for foreachbdf() macro - return next device
int
pci_next(int bdf, int bus)
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