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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 <keith.busch@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Lukas Wunner <lukas@wunner.de>
This commit is contained in:
Keith Busch 2016-04-28 16:24:48 -06:00 committed by Bjorn Helgaas
parent 10126ac14d
commit 26e5157133
4 changed files with 196 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/pci/pcie/Kconfig
View File

@ -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.

2
drivers/pci/pcie/Makefile
View File

@ -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

163
drivers/pci/pcie/pcie-dpc.c Normal file
View File

@ -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 <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/pcieport_if.h>
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 <keith.busch@intel.com>");
MODULE_LICENSE("GPL");
MODULE_VERSION("0.1");
module_init(dpc_service_init);
module_exit(dpc_service_exit);

17
include/uapi/linux/pci_regs.h
View File

@ -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 */