pci: improve PCI bus discovery
When we discovery devices on a PCI BUS, we block bridges, and
we use PCI_SECONDARY_BUS to create a linked list of bridges to
recursively setup new buses. This avoids a second visit of all the
addresses on the bus.
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/pci.c b/pci.c
index d1d6f63..1457d17 100644
--- a/pci.c
+++ b/pci.c
@@ -3,8 +3,11 @@
#include "pci.h"
static uint16_t addend;
-static uint8_t bus, max_bus;
+static uint8_t bus, max_bus, bridge_head;
static bool use_i440fx_routing;
+static int bridge_count;
+
+static void do_setup_pci_bus(void);
static void pci_foreach(void(*fn)(uint32_t bdf, uint32_t id, uint8_t type))
{
@@ -59,25 +62,10 @@
pci_config_writeb(bdf, PCI_INTERRUPT_LINE, irq);
}
-static void do_block_pci_bridges(uint32_t bdf, uint32_t id, uint8_t type)
-{
- uint16_t class;
-
- class = pci_config_readw(bdf, PCI_CLASS_DEVICE);
- switch (class) {
- case PCI_CLASS_BRIDGE_PCI:
- /* prevent accidental access to unintended devices */
- pci_config_writeb(bdf, PCI_SECONDARY_BUS, 255);
- pci_config_writeb(bdf, PCI_SUBORDINATE_BUS, 0);
- break;
- }
-}
-
static void do_setup_pci(uint32_t bdf, uint32_t id, uint8_t type)
{
uint16_t class;
uint8_t pin;
- int save_bus;
pin = pci_config_readb(bdf, PCI_INTERRUPT_PIN);
if (pin != 0)
@@ -107,21 +95,51 @@
break;
case PCI_CLASS_BRIDGE_PCI:
- save_bus = bus;
pci_config_writeb(bdf, PCI_PRIMARY_BUS, bus);
+ /* prevent accidental access to unintended devices */
+ pci_config_writeb(bdf, PCI_SUBORDINATE_BUS, 0);
+ /*
+ * Insert at the head of a linked list of bridges.
+ * do_setup_pci_bus will use it later to initialize secondary
+ * buses with a recursive call.
+ */
+ pci_config_writeb(bdf, PCI_SECONDARY_BUS, bridge_head);
+ bridge_head = (uint8_t)(bdf & 0xFF);
+ bridge_count++;
+ break;
+ }
+}
+
+static void do_setup_pci_bus(void)
+{
+ uint8_t save_bus, next_head;
+ int i;
+
+ bridge_head = 0xFF;
+ bridge_count = 0;
+
+ /* Discover all PCI devices and block bridges */
+ pci_foreach(do_setup_pci);
+
+ next_head = bridge_head;
+ save_bus = bus;
+
+ /* Configure bridges on this bus and recursively setup new busses */
+ for (i = bridge_count; i > 0; i--) {
+ uint32_t bdf = (save_bus * 256) + next_head;
+
+ next_head = pci_config_readb(bdf, PCI_SECONDARY_BUS);
+
bus = ++max_bus;
pci_config_writeb(bdf, PCI_SECONDARY_BUS, bus);
pci_config_writeb(bdf, PCI_SUBORDINATE_BUS, 255);
/* Add PCI bridge device id for the recursive call. */
addend += (bdf >> 3) & 0x1f;
- pci_foreach(do_block_pci_bridges);
- pci_foreach(do_setup_pci);
+ do_setup_pci_bus();
addend -= (bdf >> 3) & 0x1f;
pci_config_writeb(bdf, PCI_SUBORDINATE_BUS, max_bus);
- bus = save_bus;
- break;
}
}
@@ -137,6 +155,5 @@
else
panic();
- pci_foreach(do_block_pci_bridges);
- pci_foreach(do_setup_pci);
+ do_setup_pci_bus();
}
