From 43b5bc4085da70469fdb1d0902bc4516304540d1 Mon Sep 17 00:00:00 2001 From: Stefano Garzarella Date: Tue, 11 Dec 2018 18:25:55 +0100 Subject: 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 Signed-off-by: Paolo Bonzini --- pci.c | 63 ++++++++++++++++++++++++++++++++++++++++----------------------- 1 file changed, 40 insertions(+), 23 deletions(-) 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 @@ static void do_setup_pci_irq(uint32_t bdf, int pin) 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 @@ static void do_setup_pci(uint32_t bdf, uint32_t id, uint8_t type) 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 @@ void setup_pci(void) else panic(); - pci_foreach(do_block_pci_bridges); - pci_foreach(do_setup_pci); + do_setup_pci_bus(); } -- cgit v1.1