diff options
Diffstat (limited to 'drivers/pci/pci.c')
| -rw-r--r-- | drivers/pci/pci.c | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index f6a4dd10d9b0..e7a3917ed389 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -5147,6 +5147,180 @@ int pcie_get_minimum_link(struct pci_dev *dev, enum pci_bus_speed *speed, EXPORT_SYMBOL(pcie_get_minimum_link); /** + * pcie_bandwidth_available - determine minimum link settings of a PCIe + * device and its bandwidth limitation + * @dev: PCI device to query + * @limiting_dev: storage for device causing the bandwidth limitation + * @speed: storage for speed of limiting device + * @width: storage for width of limiting device + * + * Walk up the PCI device chain and find the point where the minimum + * bandwidth is available. Return the bandwidth available there and (if + * limiting_dev, speed, and width pointers are supplied) information about + * that point. The bandwidth returned is in Mb/s, i.e., megabits/second of + * raw bandwidth. + */ +u32 pcie_bandwidth_available(struct pci_dev *dev, struct pci_dev **limiting_dev, + enum pci_bus_speed *speed, + enum pcie_link_width *width) +{ + u16 lnksta; + enum pci_bus_speed next_speed; + enum pcie_link_width next_width; + u32 bw, next_bw; + + if (speed) + *speed = PCI_SPEED_UNKNOWN; + if (width) + *width = PCIE_LNK_WIDTH_UNKNOWN; + + bw = 0; + + while (dev) { + pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &lnksta); + + next_speed = pcie_link_speed[lnksta & PCI_EXP_LNKSTA_CLS]; + next_width = (lnksta & PCI_EXP_LNKSTA_NLW) >> + PCI_EXP_LNKSTA_NLW_SHIFT; + + next_bw = next_width * PCIE_SPEED2MBS_ENC(next_speed); + + /* Check if current device limits the total bandwidth */ + if (!bw || next_bw <= bw) { + bw = next_bw; + + if (limiting_dev) + *limiting_dev = dev; + if (speed) + *speed = next_speed; + if (width) + *width = next_width; + } + + dev = pci_upstream_bridge(dev); + } + + return bw; +} +EXPORT_SYMBOL(pcie_bandwidth_available); + +/** + * pcie_get_speed_cap - query for the PCI device's link speed capability + * @dev: PCI device to query + * + * Query the PCI device speed capability. Return the maximum link speed + * supported by the device. + */ +enum pci_bus_speed pcie_get_speed_cap(struct pci_dev *dev) +{ + u32 lnkcap2, lnkcap; + + /* + * PCIe r4.0 sec 7.5.3.18 recommends using the Supported Link + * Speeds Vector in Link Capabilities 2 when supported, falling + * back to Max Link Speed in Link Capabilities otherwise. + */ + pcie_capability_read_dword(dev, PCI_EXP_LNKCAP2, &lnkcap2); + if (lnkcap2) { /* PCIe r3.0-compliant */ + if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_16_0GB) + return PCIE_SPEED_16_0GT; + else if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_8_0GB) + return PCIE_SPEED_8_0GT; + else if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_5_0GB) + return PCIE_SPEED_5_0GT; + else if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_2_5GB) + return PCIE_SPEED_2_5GT; + return PCI_SPEED_UNKNOWN; + } + + pcie_capability_read_dword(dev, PCI_EXP_LNKCAP, &lnkcap); + if (lnkcap) { + if (lnkcap & PCI_EXP_LNKCAP_SLS_16_0GB) + return PCIE_SPEED_16_0GT; + else if (lnkcap & PCI_EXP_LNKCAP_SLS_8_0GB) + return PCIE_SPEED_8_0GT; + else if (lnkcap & PCI_EXP_LNKCAP_SLS_5_0GB) + return PCIE_SPEED_5_0GT; + else if (lnkcap & PCI_EXP_LNKCAP_SLS_2_5GB) + return PCIE_SPEED_2_5GT; + } + + return PCI_SPEED_UNKNOWN; +} + +/** + * pcie_get_width_cap - query for the PCI device's link width capability + * @dev: PCI device to query + * + * Query the PCI device width capability. Return the maximum link width + * supported by the device. + */ +enum pcie_link_width pcie_get_width_cap(struct pci_dev *dev) +{ + u32 lnkcap; + + pcie_capability_read_dword(dev, PCI_EXP_LNKCAP, &lnkcap); + if (lnkcap) + return (lnkcap & PCI_EXP_LNKCAP_MLW) >> 4; + + return PCIE_LNK_WIDTH_UNKNOWN; +} + +/** + * pcie_bandwidth_capable - calculate a PCI device's link bandwidth capability + * @dev: PCI device + * @speed: storage for link speed + * @width: storage for link width + * + * Calculate a PCI device's link bandwidth by querying for its link speed + * and width, multiplying them, and applying encoding overhead. The result + * is in Mb/s, i.e., megabits/second of raw bandwidth. + */ +u32 pcie_bandwidth_capable(struct pci_dev *dev, enum pci_bus_speed *speed, + enum pcie_link_width *width) +{ + *speed = pcie_get_speed_cap(dev); + *width = pcie_get_width_cap(dev); + + if (*speed == PCI_SPEED_UNKNOWN || *width == PCIE_LNK_WIDTH_UNKNOWN) + return 0; + + return *width * PCIE_SPEED2MBS_ENC(*speed); +} + +/** + * pcie_print_link_status - Report the PCI device's link speed and width + * @dev: PCI device to query + * + * Report the available bandwidth at the device. If this is less than the + * device is capable of, report the device's maximum possible bandwidth and + * the upstream link that limits its performance to less than that. + */ +void pcie_print_link_status(struct pci_dev *dev) +{ + enum pcie_link_width width, width_cap; + enum pci_bus_speed speed, speed_cap; + struct pci_dev *limiting_dev = NULL; + u32 bw_avail, bw_cap; + + bw_cap = pcie_bandwidth_capable(dev, &speed_cap, &width_cap); + bw_avail = pcie_bandwidth_available(dev, &limiting_dev, &speed, &width); + + if (bw_avail >= bw_cap) + pci_info(dev, "%u.%03u Gb/s available bandwidth (%s x%d link)\n", + bw_cap / 1000, bw_cap % 1000, + PCIE_SPEED2STR(speed_cap), width_cap); + else + pci_info(dev, "%u.%03u Gb/s available bandwidth, limited by %s x%d link at %s (capable of %u.%03u Gb/s with %s x%d link)\n", + bw_avail / 1000, bw_avail % 1000, + PCIE_SPEED2STR(speed), width, + limiting_dev ? pci_name(limiting_dev) : "<unknown>", + bw_cap / 1000, bw_cap % 1000, + PCIE_SPEED2STR(speed_cap), width_cap); +} +EXPORT_SYMBOL(pcie_print_link_status); + +/** * pci_select_bars - Make BAR mask from the type of resource * @dev: the PCI device for which BAR mask is made * @flags: resource type mask to be selected |