diff options
| -rw-r--r-- | drivers/cxl/core/core.h | 2 | ||||
| -rw-r--r-- | drivers/cxl/core/pci.c | 36 | ||||
| -rw-r--r-- | drivers/cxl/core/port.c | 6 | ||||
| -rw-r--r-- | drivers/cxl/cxl.h | 4 | ||||
| -rw-r--r-- | drivers/cxl/cxlpci.h | 13 | ||||
| -rw-r--r-- | drivers/pci/pci.c | 38 | ||||
| -rw-r--r-- | include/linux/pci.h | 1 |
7 files changed, 98 insertions, 2 deletions
diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h index 86d7ba23235e..3b64fb1b9ed0 100644 --- a/drivers/cxl/core/core.h +++ b/drivers/cxl/core/core.h @@ -88,4 +88,6 @@ enum cxl_poison_trace_type { CXL_POISON_TRACE_CLEAR, }; +long cxl_pci_get_latency(struct pci_dev *pdev); + #endif /* __CXL_CORE_H__ */ diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c index 37e1652afbc7..6c9c8d92f8f7 100644 --- a/drivers/cxl/core/pci.c +++ b/drivers/cxl/core/pci.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0-only /* Copyright(c) 2021 Intel Corporation. All rights reserved. */ +#include <linux/units.h> #include <linux/io-64-nonatomic-lo-hi.h> #include <linux/device.h> #include <linux/delay.h> @@ -979,3 +980,38 @@ pci_ers_result_t cxl_error_detected(struct pci_dev *pdev, return PCI_ERS_RESULT_NEED_RESET; } EXPORT_SYMBOL_NS_GPL(cxl_error_detected, CXL); + +static int cxl_flit_size(struct pci_dev *pdev) +{ + if (cxl_pci_flit_256(pdev)) + return 256; + + return 68; +} + +/** + * cxl_pci_get_latency - calculate the link latency for the PCIe link + * @pdev: PCI device + * + * return: calculated latency or 0 for no latency + * + * CXL Memory Device SW Guide v1.0 2.11.4 Link latency calculation + * Link latency = LinkPropagationLatency + FlitLatency + RetimerLatency + * LinkProgationLatency is negligible, so 0 will be used + * RetimerLatency is assumed to be negligible and 0 will be used + * FlitLatency = FlitSize / LinkBandwidth + * FlitSize is defined by spec. CXL rev3.0 4.2.1. + * 68B flit is used up to 32GT/s. >32GT/s, 256B flit size is used. + * The FlitLatency is converted to picoseconds. + */ +long cxl_pci_get_latency(struct pci_dev *pdev) +{ + long bw; + + bw = pcie_link_speed_mbps(pdev); + if (bw < 0) + return 0; + bw /= BITS_PER_BYTE; + + return cxl_flit_size(pdev) * MEGA / bw; +} diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c index 9393cbf04652..b5ad227fe0d8 100644 --- a/drivers/cxl/core/port.c +++ b/drivers/cxl/core/port.c @@ -854,6 +854,9 @@ static struct cxl_port *__devm_cxl_add_port(struct device *host, if (rc) return ERR_PTR(rc); + if (parent_dport && dev_is_pci(uport_dev)) + port->pci_latency = cxl_pci_get_latency(to_pci_dev(uport_dev)); + return port; err: @@ -1137,6 +1140,9 @@ __devm_cxl_add_dport(struct cxl_port *port, struct device *dport_dev, if (rc) return ERR_PTR(rc); + if (dev_is_pci(dport_dev)) + dport->link_latency = cxl_pci_get_latency(to_pci_dev(dport_dev)); + return dport; } diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h index abbdcd3a7596..7da8db919a20 100644 --- a/drivers/cxl/cxl.h +++ b/drivers/cxl/cxl.h @@ -591,6 +591,7 @@ struct cxl_dax_region { * @depth: How deep this port is relative to the root. depth 0 is the root. * @cdat: Cached CDAT data * @cdat_available: Should a CDAT attribute be available in sysfs + * @pci_latency: Upstream latency in picoseconds */ struct cxl_port { struct device dev; @@ -613,6 +614,7 @@ struct cxl_port { size_t length; } cdat; bool cdat_available; + long pci_latency; }; struct cxl_root_ops { @@ -659,6 +661,7 @@ struct cxl_rcrb_info { * @port: reference to cxl_port that contains this downstream port * @regs: Dport parsed register blocks * @sw_coord: access coordinates (performance) for switch from CDAT + * @link_latency: calculated PCIe downstream latency */ struct cxl_dport { struct device *dport_dev; @@ -669,6 +672,7 @@ struct cxl_dport { struct cxl_port *port; struct cxl_regs regs; struct access_coordinate sw_coord; + long link_latency; }; /** diff --git a/drivers/cxl/cxlpci.h b/drivers/cxl/cxlpci.h index 0fa4799ea316..711b05d9a370 100644 --- a/drivers/cxl/cxlpci.h +++ b/drivers/cxl/cxlpci.h @@ -85,6 +85,19 @@ struct cdat_entry_header { __le16 length; } __packed; +/* + * CXL v3.0 6.2.3 Table 6-4 + * The table indicates that if PCIe Flit Mode is set, then CXL is in 256B flits + * mode, otherwise it's 68B flits mode. + */ +static inline bool cxl_pci_flit_256(struct pci_dev *pdev) +{ + u16 lnksta2; + + pcie_capability_read_word(pdev, PCI_EXP_LNKSTA2, &lnksta2); + return lnksta2 & PCI_EXP_LNKSTA2_FLIT; +} + int devm_cxl_port_enumerate_dports(struct cxl_port *port); struct cxl_dev_state; int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm, diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 55bc3576a985..00817d403ad4 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -6224,6 +6224,41 @@ int pcie_set_mps(struct pci_dev *dev, int mps) } EXPORT_SYMBOL(pcie_set_mps); +static enum pci_bus_speed to_pcie_link_speed(u16 lnksta) +{ + return pcie_link_speed[FIELD_GET(PCI_EXP_LNKSTA_CLS, lnksta)]; +} + +int pcie_link_speed_mbps(struct pci_dev *pdev) +{ + u16 lnksta; + int err; + + err = pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnksta); + if (err) + return err; + + switch (to_pcie_link_speed(lnksta)) { + case PCIE_SPEED_2_5GT: + return 2500; + case PCIE_SPEED_5_0GT: + return 5000; + case PCIE_SPEED_8_0GT: + return 8000; + case PCIE_SPEED_16_0GT: + return 16000; + case PCIE_SPEED_32_0GT: + return 32000; + case PCIE_SPEED_64_0GT: + return 64000; + default: + break; + } + + return -EINVAL; +} +EXPORT_SYMBOL(pcie_link_speed_mbps); + /** * pcie_bandwidth_available - determine minimum link settings of a PCIe * device and its bandwidth limitation @@ -6257,8 +6292,7 @@ u32 pcie_bandwidth_available(struct pci_dev *dev, struct pci_dev **limiting_dev, while (dev) { pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &lnksta); - next_speed = pcie_link_speed[FIELD_GET(PCI_EXP_LNKSTA_CLS, - lnksta)]; + next_speed = to_pcie_link_speed(lnksta); next_width = FIELD_GET(PCI_EXP_LNKSTA_NLW, lnksta); next_bw = next_width * PCIE_SPEED2MBS_ENC(next_speed); diff --git a/include/linux/pci.h b/include/linux/pci.h index dea043bc1e38..504a4ba2c29e 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1364,6 +1364,7 @@ int pcie_set_mps(struct pci_dev *dev, int mps); u32 pcie_bandwidth_available(struct pci_dev *dev, struct pci_dev **limiting_dev, enum pci_bus_speed *speed, enum pcie_link_width *width); +int pcie_link_speed_mbps(struct pci_dev *pdev); void pcie_print_link_status(struct pci_dev *dev); int pcie_reset_flr(struct pci_dev *dev, bool probe); int pcie_flr(struct pci_dev *dev); |