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Fri, 21 Aug 2020 12:14:11 -0700 (PDT) From: Puranjay Mohan To: bjorn@helgaas.com Date: Sat, 22 Aug 2020 00:43:56 +0530 Message-Id: <20200821191356.7669-1-puranjay12@gmail.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 Cc: linux-pci@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, Puranjay Mohan Subject: [Linux-kernel-mentees] [PATCH] PCI: Add support for LTR X-BeenThere: linux-kernel-mentees@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-kernel-mentees-bounces@lists.linuxfoundation.org Sender: "Linux-kernel-mentees" Add a new function pci_ltr_init() which will be called from pci_init_capabilities() to initialize every PCIe device's LTR values. Add code in probe.c to evaluate LTR _DSM and save the latencies in pci_dev. Signed-off-by: Puranjay Mohan --- drivers/pci/pci-acpi.c | 28 ++++++++++++++++++++++++++++ drivers/pci/pci.c | 26 ++++++++++++++++++++++++++ drivers/pci/pci.h | 5 +++++ drivers/pci/probe.c | 6 ++++++ include/linux/pci-acpi.h | 1 + include/linux/pci.h | 2 ++ 6 files changed, 68 insertions(+) diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c index 7224b1e5f2a8..c9151f96f3c9 100644 --- a/drivers/pci/pci-acpi.c +++ b/drivers/pci/pci-acpi.c @@ -1213,6 +1213,34 @@ static void pci_acpi_optimize_delay(struct pci_dev *pdev, ACPI_FREE(obj); } +/* pci_acpi_evaluate_ltr_latency + * + * @dev - the pci_dev to evaluate and save latencies + */ +void pci_acpi_evaluate_ltr_latency(struct pci_dev *dev) +{ + union acpi_object *obj, *elements; + struct acpi_device *handle; + + handle = ACPI_HANDLE(&dev->dev); + if (!handle) + return; + + obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, 0x2, + DSM_PCI_LTR_MAX_LATENCY, NULL); + if (!obj) + return; + + if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 4) { + elements = obj->package.elements; + dev->max_snoop_latency = (u16)elements[1].integer.value | + ((u16)elements[0].integer.value << PCI_LTR_SCALE_SHIFT); + dev->max_nosnoop_latency = (u16)elements[3].integer.value | + ((u16)elements[2].integer.value << PCI_LTR_SCALE_SHIFT); + } + ACPI_FREE(obj); +} + static void pci_acpi_set_untrusted(struct pci_dev *dev) { u8 val; diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index c9338f914a0e..8aa71175ebea 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -2921,6 +2921,32 @@ void pci_pm_init(struct pci_dev *dev) dev->imm_ready = 1; } +/** + * pci_ltr_init - Initialize Latency Tolerance Information of given PCI device + * @dev: PCI device to handle. + */ +void pci_ltr_init(struct pci_dev *dev) +{ +#ifdef CONFIG_PCIASPM + int ltr; + struct pci_dev *endpoint_dev = dev; + u16 max_snoop_sum = 0; + u16 max_nosnoop_sum = 0; + + ltr = pci_find_ext_capability(endpoint_dev, PCI_EXT_CAP_ID_LTR); + if (!ltr) + return; + + dev = pci_upstream_bridge(dev); + while (dev) { + max_snoop_sum += dev->max_snoop_latency; + max_nosnoop_sum += dev->max_nosnoop_latency; + dev = pci_upstream_bridge(dev); + } + pci_write_config_word(endpoint_dev, ltr + PCI_LTR_MAX_SNOOP_LAT, max_snoop_sum); + pci_write_config_word(endpoint_dev, ltr + PCI_LTR_MAX_NOSNOOP_LAT, max_nosnoop_sum); +#endif +} static unsigned long pci_ea_flags(struct pci_dev *dev, u8 prop) { unsigned long flags = IORESOURCE_PCI_FIXED | IORESOURCE_PCI_EA_BEI; diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h index 6d3f75867106..f824dd977dd3 100644 --- a/drivers/pci/pci.h +++ b/drivers/pci/pci.h @@ -109,6 +109,7 @@ void pci_free_cap_save_buffers(struct pci_dev *dev); bool pci_bridge_d3_possible(struct pci_dev *dev); void pci_bridge_d3_update(struct pci_dev *dev); void pci_bridge_wait_for_secondary_bus(struct pci_dev *dev); +void pci_ltr_init(struct pci_dev *dev); static inline void pci_wakeup_event(struct pci_dev *dev) { @@ -673,11 +674,15 @@ static inline int pci_aer_raw_clear_status(struct pci_dev *dev) { return -EINVAL #ifdef CONFIG_ACPI int pci_acpi_program_hp_params(struct pci_dev *dev); +void pci_acpi_evaluate_ltr_latency(struct pci_dev *dev); #else static inline int pci_acpi_program_hp_params(struct pci_dev *dev) { return -ENODEV; } +static inline void pci_acpi_evaluate_ltr_latency(struct pci_dev *dev) +{ +} #endif #ifdef CONFIG_PCIEASPM diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 2f66988cea25..0bc9d7e6a0e9 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2134,6 +2134,11 @@ static void pci_configure_ltr(struct pci_dev *dev) dev->ltr_path = 1; } #endif + + /* + * Read latency values from _DSM and save in pci_dev + */ + pci_acpi_evaluate_ltr_latency(dev); } static void pci_configure_eetlp_prefix(struct pci_dev *dev) @@ -2394,6 +2399,7 @@ static void pci_init_capabilities(struct pci_dev *dev) pci_ptm_init(dev); /* Precision Time Measurement */ pci_aer_init(dev); /* Advanced Error Reporting */ pci_dpc_init(dev); /* Downstream Port Containment */ + pci_ltr_init(dev); /* Latency Tolerance Reporting */ pcie_report_downtraining(dev); diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h index 5ba475ca9078..e23236a4ff66 100644 --- a/include/linux/pci-acpi.h +++ b/include/linux/pci-acpi.h @@ -110,6 +110,7 @@ extern const guid_t pci_acpi_dsm_guid; /* _DSM Definitions for PCI */ #define DSM_PCI_PRESERVE_BOOT_CONFIG 0x05 +#define DSM_PCI_LTR_MAX_LATENCY 0x06 #define DSM_PCI_DEVICE_NAME 0x07 #define DSM_PCI_POWER_ON_RESET_DELAY 0x08 #define DSM_PCI_DEVICE_READINESS_DURATIONS 0x09 diff --git a/include/linux/pci.h b/include/linux/pci.h index 34c1c4f45288..e407c8cba2d3 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -380,6 +380,8 @@ struct pci_dev { struct pcie_link_state *link_state; /* ASPM link state */ unsigned int ltr_path:1; /* Latency Tolerance Reporting supported from root to here */ + u16 max_snoop_latency; /* LTR Max Snoop latency */ + u16 max_nosnoop_latency; /* LTR Max No Snoop latency */ #endif unsigned int eetlp_prefix_path:1; /* End-to-End TLP Prefix */ -- 2.27.0 _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees