diff options
Diffstat (limited to 'arch/x86/kernel/amd_node.c')
| -rw-r--r-- | arch/x86/kernel/amd_node.c | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c index e825cd4426b9..4eea8c7d8090 100644 --- a/arch/x86/kernel/amd_node.c +++ b/arch/x86/kernel/amd_node.c @@ -32,3 +32,59 @@ struct pci_dev *amd_node_get_func(u16 node, u8 func) return pci_get_domain_bus_and_slot(0, 0, PCI_DEVFN(AMD_NODE0_PCI_SLOT + node, func)); } + +#define DF_BLK_INST_CNT 0x040 +#define DF_CFG_ADDR_CNTL_LEGACY 0x084 +#define DF_CFG_ADDR_CNTL_DF4 0xC04 + +#define DF_MAJOR_REVISION GENMASK(27, 24) + +static u16 get_cfg_addr_cntl_offset(struct pci_dev *df_f0) +{ + u32 reg; + + /* + * Revision fields added for DF4 and later. + * + * Major revision of '0' is found pre-DF4. Field is Read-as-Zero. + */ + if (pci_read_config_dword(df_f0, DF_BLK_INST_CNT, ®)) + return 0; + + if (reg & DF_MAJOR_REVISION) + return DF_CFG_ADDR_CNTL_DF4; + + return DF_CFG_ADDR_CNTL_LEGACY; +} + +struct pci_dev *amd_node_get_root(u16 node) +{ + struct pci_dev *root; + u16 cntl_off; + u8 bus; + + if (!cpu_feature_enabled(X86_FEATURE_ZEN)) + return NULL; + + /* + * D18F0xXXX [Config Address Control] (DF::CfgAddressCntl) + * Bits [7:0] (SecBusNum) holds the bus number of the root device for + * this Data Fabric instance. The segment, device, and function will be 0. + */ + struct pci_dev *df_f0 __free(pci_dev_put) = amd_node_get_func(node, 0); + if (!df_f0) + return NULL; + + cntl_off = get_cfg_addr_cntl_offset(df_f0); + if (!cntl_off) + return NULL; + + if (pci_read_config_byte(df_f0, cntl_off, &bus)) + return NULL; + + /* Grab the pointer for the actual root device instance. */ + root = pci_get_domain_bus_and_slot(0, bus, 0); + + pci_dbg(root, "is root for AMD node %u\n", node); + return root; +} |