diff options
| -rw-r--r-- | drivers/pci/probe.c | 54 | ||||
| -rw-r--r-- | include/uapi/linux/pci_regs.h | 6 |
2 files changed, 56 insertions, 4 deletions
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 012250a78da7..a6874c306908 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1086,6 +1086,36 @@ static void pci_enable_crs(struct pci_dev *pdev) static unsigned int pci_scan_child_bus_extend(struct pci_bus *bus, unsigned int available_buses); +/** + * pci_ea_fixed_busnrs() - Read fixed Secondary and Subordinate bus + * numbers from EA capability. + * @dev: Bridge + * @sec: updated with secondary bus number from EA + * @sub: updated with subordinate bus number from EA + * + * If @dev is a bridge with EA capability, update @sec and @sub with + * fixed bus numbers from the capability and return true. Otherwise, + * return false. + */ +static bool pci_ea_fixed_busnrs(struct pci_dev *dev, u8 *sec, u8 *sub) +{ + int ea, offset; + u32 dw; + + if (dev->hdr_type != PCI_HEADER_TYPE_BRIDGE) + return false; + + /* find PCI EA capability in list */ + ea = pci_find_capability(dev, PCI_CAP_ID_EA); + if (!ea) + return false; + + offset = ea + PCI_EA_FIRST_ENT; + pci_read_config_dword(dev, offset, &dw); + *sec = dw & PCI_EA_SEC_BUS_MASK; + *sub = (dw & PCI_EA_SUB_BUS_MASK) >> PCI_EA_SUB_BUS_SHIFT; + return true; +} /* * pci_scan_bridge_extend() - Scan buses behind a bridge @@ -1120,6 +1150,9 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev, u16 bctl; u8 primary, secondary, subordinate; int broken = 0; + bool fixed_buses; + u8 fixed_sec, fixed_sub; + int next_busnr; /* * Make sure the bridge is powered on to be able to access config @@ -1219,17 +1252,24 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev, /* Clear errors */ pci_write_config_word(dev, PCI_STATUS, 0xffff); + /* Read bus numbers from EA Capability (if present) */ + fixed_buses = pci_ea_fixed_busnrs(dev, &fixed_sec, &fixed_sub); + if (fixed_buses) + next_busnr = fixed_sec; + else + next_busnr = max + 1; + /* * Prevent assigning a bus number that already exists. * This can happen when a bridge is hot-plugged, so in this * case we only re-scan this bus. */ - child = pci_find_bus(pci_domain_nr(bus), max+1); + child = pci_find_bus(pci_domain_nr(bus), next_busnr); if (!child) { - child = pci_add_new_bus(bus, dev, max+1); + child = pci_add_new_bus(bus, dev, next_busnr); if (!child) goto out; - pci_bus_insert_busn_res(child, max+1, + pci_bus_insert_busn_res(child, next_busnr, bus->busn_res.end); } max++; @@ -1290,7 +1330,13 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev, max += i; } - /* Set subordinate bus number to its real value */ + /* + * Set subordinate bus number to its real value. + * If fixed subordinate bus number exists from EA + * capability then use it. + */ + if (fixed_buses) + max = fixed_sub; pci_bus_update_busn_res_end(child, max); pci_write_config_byte(dev, PCI_SUBORDINATE_BUS, max); } diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h index 5c98133f2c94..c51e0066de8b 100644 --- a/include/uapi/linux/pci_regs.h +++ b/include/uapi/linux/pci_regs.h @@ -372,6 +372,12 @@ #define PCI_EA_FIRST_ENT_BRIDGE 8 /* First EA Entry for Bridges */ #define PCI_EA_ES 0x00000007 /* Entry Size */ #define PCI_EA_BEI 0x000000f0 /* BAR Equivalent Indicator */ + +/* EA fixed Secondary and Subordinate bus numbers for Bridge */ +#define PCI_EA_SEC_BUS_MASK 0xff +#define PCI_EA_SUB_BUS_MASK 0xff00 +#define PCI_EA_SUB_BUS_SHIFT 8 + /* 0-5 map to BARs 0-5 respectively */ #define PCI_EA_BEI_BAR0 0 #define PCI_EA_BEI_BAR5 5 |