From 26e515713342b6f7c553aa3c66b21c6ab7cf82af Mon Sep 17 00:00:00 2001 From: Keith Busch Date: Thu, 28 Apr 2016 16:24:48 -0600 Subject: [PATCH] PCI: Add Downstream Port Containment driver Add driver for the PCI Express Downstream Port Containment extended capability. DPC is an optional capability to contain uncorrectable errors below a port. For more information on DPC, please see PCI Express Base Specification Revision 4, section 7.31, or view the PCI-SIG DPC ECN here: https://pcisig.com/sites/default/files/specification_documents/ECN_DPC_2012-02-09_finalized.pdf When a DPC event is triggered, the hardware disables downstream links, so the DPC driver schedules removal for all devices below this port. This may happen concurrently with a PCIe hotplug driver if enabled. When all downstream devices are removed and the link state transitions to disabled, the DPC driver clears the DPC status and interrupt bits so the link may retrain for a newly connected device. [bhelgaas: clear (not set) DPC_CTL bits on remove, whitespace cleanup] Signed-off-by: Keith Busch Signed-off-by: Bjorn Helgaas Cc: Lukas Wunner --- drivers/pci/pcie/Kconfig | 14 +++ drivers/pci/pcie/Makefile | 2 + drivers/pci/pcie/pcie-dpc.c | 163 ++++++++++++++++++++++++++++++++++ include/uapi/linux/pci_regs.h | 17 ++++ 4 files changed, 196 insertions(+) create mode 100644 drivers/pci/pcie/pcie-dpc.c diff --git a/drivers/pci/pcie/Kconfig b/drivers/pci/pcie/Kconfig index 72db7f4209ca..22ca6412bd15 100644 --- a/drivers/pci/pcie/Kconfig +++ b/drivers/pci/pcie/Kconfig @@ -81,3 +81,17 @@ endchoice config PCIE_PME def_bool y depends on PCIEPORTBUS && PM + +config PCIE_DPC + tristate "PCIe Downstream Port Containment support" + depends on PCIEPORTBUS + default n + help + This enables PCI Express Downstream Port Containment (DPC) + driver support. DPC events from Root and Downstream ports + will be handled by the DPC driver. If your system doesn't + have this capability or you do not want to use this feature, + it is safe to answer N. + + To compile this driver as a module, choose M here: the module + will be called pcie-dpc. diff --git a/drivers/pci/pcie/Makefile b/drivers/pci/pcie/Makefile index 00c62df5a9fc..b24525b3dec1 100644 --- a/drivers/pci/pcie/Makefile +++ b/drivers/pci/pcie/Makefile @@ -14,3 +14,5 @@ obj-$(CONFIG_PCIEPORTBUS) += pcieportdrv.o obj-$(CONFIG_PCIEAER) += aer/ obj-$(CONFIG_PCIE_PME) += pme.o + +obj-$(CONFIG_PCIE_DPC) += pcie-dpc.o diff --git a/drivers/pci/pcie/pcie-dpc.c b/drivers/pci/pcie/pcie-dpc.c new file mode 100644 index 000000000000..ab552f1bc08f --- /dev/null +++ b/drivers/pci/pcie/pcie-dpc.c @@ -0,0 +1,163 @@ +/* + * PCI Express Downstream Port Containment services driver + * Copyright (C) 2016 Intel Corp. + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + */ + +#include +#include +#include +#include +#include + +struct dpc_dev { + struct pcie_device *dev; + struct work_struct work; + int cap_pos; +}; + +static void dpc_wait_link_inactive(struct pci_dev *pdev) +{ + unsigned long timeout = jiffies + HZ; + u16 lnk_status; + + pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status); + while (lnk_status & PCI_EXP_LNKSTA_DLLLA && + !time_after(jiffies, timeout)) { + msleep(10); + pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status); + } + if (lnk_status & PCI_EXP_LNKSTA_DLLLA) + dev_warn(&pdev->dev, "Link state not disabled for DPC event"); +} + +static void interrupt_event_handler(struct work_struct *work) +{ + struct dpc_dev *dpc = container_of(work, struct dpc_dev, work); + struct pci_dev *dev, *temp, *pdev = dpc->dev->port; + struct pci_bus *parent = pdev->subordinate; + + pci_lock_rescan_remove(); + list_for_each_entry_safe_reverse(dev, temp, &parent->devices, + bus_list) { + pci_dev_get(dev); + pci_stop_and_remove_bus_device(dev); + pci_dev_put(dev); + } + pci_unlock_rescan_remove(); + + dpc_wait_link_inactive(pdev); + pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS, + PCI_EXP_DPC_STATUS_TRIGGER | PCI_EXP_DPC_STATUS_INTERRUPT); +} + +static irqreturn_t dpc_irq(int irq, void *context) +{ + struct dpc_dev *dpc = (struct dpc_dev *)context; + struct pci_dev *pdev = dpc->dev->port; + u16 status, source; + + pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS, &status); + pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_SOURCE_ID, + &source); + if (!status) + return IRQ_NONE; + + dev_info(&dpc->dev->device, "DPC containment event, status:%#06x source:%#06x\n", + status, source); + + if (status & PCI_EXP_DPC_STATUS_TRIGGER) { + u16 reason = (status >> 1) & 0x3; + + dev_warn(&dpc->dev->device, "DPC %s triggered, remove downstream devices\n", + (reason == 0) ? "unmasked uncorrectable error" : + (reason == 1) ? "ERR_NONFATAL" : + (reason == 2) ? "ERR_FATAL" : "extended error"); + schedule_work(&dpc->work); + } + return IRQ_HANDLED; +} + +#define FLAG(x, y) (((x) & (y)) ? '+' : '-') +static int dpc_probe(struct pcie_device *dev) +{ + struct dpc_dev *dpc; + struct pci_dev *pdev = dev->port; + int status; + u16 ctl, cap; + + dpc = kzalloc(sizeof(*dpc), GFP_KERNEL); + if (!dpc) + return -ENOMEM; + + dpc->cap_pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_DPC); + dpc->dev = dev; + INIT_WORK(&dpc->work, interrupt_event_handler); + set_service_data(dev, dpc); + + status = request_irq(dev->irq, dpc_irq, IRQF_SHARED, "pcie-dpc", dpc); + if (status) { + dev_warn(&dev->device, "request IRQ%d failed: %d\n", dev->irq, + status); + goto out; + } + + pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CAP, &cap); + pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, &ctl); + + ctl |= PCI_EXP_DPC_CTL_EN_NONFATAL | PCI_EXP_DPC_CTL_INT_EN; + pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, ctl); + + dev_info(&dev->device, "DPC error containment capabilities: Int Msg #%d, RPExt%c PoisonedTLP%c SwTrigger%c RP PIO Log %d, DL_ActiveErr%c\n", + cap & 0xf, FLAG(cap, PCI_EXP_DPC_CAP_RP_EXT), + FLAG(cap, PCI_EXP_DPC_CAP_POISONED_TLP), + FLAG(cap, PCI_EXP_DPC_CAP_SW_TRIGGER), (cap >> 8) & 0xf, + FLAG(cap, PCI_EXP_DPC_CAP_DL_ACTIVE)); + return status; + out: + kfree(dpc); + return status; +} + +static void dpc_remove(struct pcie_device *dev) +{ + struct dpc_dev *dpc = get_service_data(dev); + struct pci_dev *pdev = dev->port; + u16 ctl; + + pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, &ctl); + ctl &= ~(PCI_EXP_DPC_CTL_EN_NONFATAL | PCI_EXP_DPC_CTL_INT_EN); + pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, ctl); + + free_irq(dev->irq, dpc); + kfree(dpc); +} + +static struct pcie_port_service_driver dpcdriver = { + .name = "dpc", + .port_type = PCI_EXP_TYPE_ROOT_PORT | PCI_EXP_TYPE_DOWNSTREAM, + .service = PCIE_PORT_SERVICE_DPC, + .probe = dpc_probe, + .remove = dpc_remove, +}; + +static int __init dpc_service_init(void) +{ + return pcie_port_service_register(&dpcdriver); +} + +static void __exit dpc_service_exit(void) +{ + pcie_port_service_unregister(&dpcdriver); +} + +MODULE_DESCRIPTION("PCI Express Downstream Port Containment driver"); +MODULE_AUTHOR("Keith Busch "); +MODULE_LICENSE("GPL"); +MODULE_VERSION("0.1"); + +module_init(dpc_service_init); +module_exit(dpc_service_exit); diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h index 61e95c142547..404095124ae2 100644 --- a/include/uapi/linux/pci_regs.h +++ b/include/uapi/linux/pci_regs.h @@ -947,4 +947,21 @@ #define PCI_TPH_CAP_ST_SHIFT 16 /* st table shift */ #define PCI_TPH_BASE_SIZEOF 12 /* size with no st table */ +/* Downstream Port Containment */ +#define PCI_EXP_DPC_CAP 4 /* DPC Capability */ +#define PCI_EXP_DPC_CAP_RP_EXT 0x20 /* Root Port Extensions for DPC */ +#define PCI_EXP_DPC_CAP_POISONED_TLP 0x40 /* Poisoned TLP Egress Blocking Supported */ +#define PCI_EXP_DPC_CAP_SW_TRIGGER 0x80 /* Software Triggering Supported */ +#define PCI_EXP_DPC_CAP_DL_ACTIVE 0x1000 /* ERR_COR signal on DL_Active supported */ + +#define PCI_EXP_DPC_CTL 6 /* DPC control */ +#define PCI_EXP_DPC_CTL_EN_NONFATAL 0x02 /* Enable trigger on ERR_NONFATAL message */ +#define PCI_EXP_DPC_CTL_INT_EN 0x08 /* DPC Interrupt Enable */ + +#define PCI_EXP_DPC_STATUS 8 /* DPC Status */ +#define PCI_EXP_DPC_STATUS_TRIGGER 0x01 /* Trigger Status */ +#define PCI_EXP_DPC_STATUS_INTERRUPT 0x08 /* Interrupt Status */ + +#define PCI_EXP_DPC_SOURCE_ID 10 /* DPC Source Identifier */ + #endif /* LINUX_PCI_REGS_H */