136 lines
3.7 KiB
C
136 lines
3.7 KiB
C
// SPDX-License-Identifier: GPL-2.0+
|
|
/*
|
|
* PCI Express Link Bandwidth Notification services driver
|
|
* Author: Alexandru Gagniuc <mr.nuke.me@gmail.com>
|
|
*
|
|
* Copyright (C) 2019, Dell Inc
|
|
*
|
|
* The PCIe Link Bandwidth Notification provides a way to notify the
|
|
* operating system when the link width or data rate changes. This
|
|
* capability is required for all root ports and downstream ports
|
|
* supporting links wider than x1 and/or multiple link speeds.
|
|
*
|
|
* This service port driver hooks into the bandwidth notification interrupt
|
|
* and warns when links become degraded in operation.
|
|
*/
|
|
|
|
#include "../pci.h"
|
|
#include "portdrv.h"
|
|
|
|
static bool pcie_link_bandwidth_notification_supported(struct pci_dev *dev)
|
|
{
|
|
int ret;
|
|
u32 lnk_cap;
|
|
|
|
ret = pcie_capability_read_dword(dev, PCI_EXP_LNKCAP, &lnk_cap);
|
|
return (ret == PCIBIOS_SUCCESSFUL) && (lnk_cap & PCI_EXP_LNKCAP_LBNC);
|
|
}
|
|
|
|
static void pcie_enable_link_bandwidth_notification(struct pci_dev *dev)
|
|
{
|
|
u16 lnk_ctl;
|
|
|
|
pcie_capability_write_word(dev, PCI_EXP_LNKSTA, PCI_EXP_LNKSTA_LBMS);
|
|
|
|
pcie_capability_read_word(dev, PCI_EXP_LNKCTL, &lnk_ctl);
|
|
lnk_ctl |= PCI_EXP_LNKCTL_LBMIE;
|
|
pcie_capability_write_word(dev, PCI_EXP_LNKCTL, lnk_ctl);
|
|
}
|
|
|
|
static void pcie_disable_link_bandwidth_notification(struct pci_dev *dev)
|
|
{
|
|
u16 lnk_ctl;
|
|
|
|
pcie_capability_read_word(dev, PCI_EXP_LNKCTL, &lnk_ctl);
|
|
lnk_ctl &= ~PCI_EXP_LNKCTL_LBMIE;
|
|
pcie_capability_write_word(dev, PCI_EXP_LNKCTL, lnk_ctl);
|
|
}
|
|
|
|
static irqreturn_t pcie_bw_notification_irq(int irq, void *context)
|
|
{
|
|
struct pcie_device *srv = context;
|
|
struct pci_dev *port = srv->port;
|
|
u16 link_status, events;
|
|
int ret;
|
|
|
|
ret = pcie_capability_read_word(port, PCI_EXP_LNKSTA, &link_status);
|
|
events = link_status & PCI_EXP_LNKSTA_LBMS;
|
|
|
|
if (ret != PCIBIOS_SUCCESSFUL || !events)
|
|
return IRQ_NONE;
|
|
|
|
pcie_capability_write_word(port, PCI_EXP_LNKSTA, events);
|
|
pcie_update_link_speed(port->subordinate, link_status);
|
|
return IRQ_WAKE_THREAD;
|
|
}
|
|
|
|
static irqreturn_t pcie_bw_notification_handler(int irq, void *context)
|
|
{
|
|
struct pcie_device *srv = context;
|
|
struct pci_dev *port = srv->port;
|
|
struct pci_dev *dev;
|
|
|
|
/*
|
|
* Print status from downstream devices, not this root port or
|
|
* downstream switch port.
|
|
*/
|
|
down_read(&pci_bus_sem);
|
|
list_for_each_entry(dev, &port->subordinate->devices, bus_list)
|
|
pcie_report_downtraining(dev);
|
|
up_read(&pci_bus_sem);
|
|
|
|
return IRQ_HANDLED;
|
|
}
|
|
|
|
static int pcie_bandwidth_notification_probe(struct pcie_device *srv)
|
|
{
|
|
int ret;
|
|
|
|
/* Single-width or single-speed ports do not have to support this. */
|
|
if (!pcie_link_bandwidth_notification_supported(srv->port))
|
|
return -ENODEV;
|
|
|
|
ret = request_threaded_irq(srv->irq, pcie_bw_notification_irq,
|
|
pcie_bw_notification_handler,
|
|
IRQF_SHARED, "PCIe BW notif", srv);
|
|
if (ret)
|
|
return ret;
|
|
|
|
pcie_enable_link_bandwidth_notification(srv->port);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void pcie_bandwidth_notification_remove(struct pcie_device *srv)
|
|
{
|
|
pcie_disable_link_bandwidth_notification(srv->port);
|
|
free_irq(srv->irq, srv);
|
|
}
|
|
|
|
static int pcie_bandwidth_notification_suspend(struct pcie_device *srv)
|
|
{
|
|
pcie_disable_link_bandwidth_notification(srv->port);
|
|
return 0;
|
|
}
|
|
|
|
static int pcie_bandwidth_notification_resume(struct pcie_device *srv)
|
|
{
|
|
pcie_enable_link_bandwidth_notification(srv->port);
|
|
return 0;
|
|
}
|
|
|
|
static struct pcie_port_service_driver pcie_bandwidth_notification_driver = {
|
|
.name = "pcie_bw_notification",
|
|
.port_type = PCIE_ANY_PORT,
|
|
.service = PCIE_PORT_SERVICE_BWNOTIF,
|
|
.probe = pcie_bandwidth_notification_probe,
|
|
.suspend = pcie_bandwidth_notification_suspend,
|
|
.resume = pcie_bandwidth_notification_resume,
|
|
.remove = pcie_bandwidth_notification_remove,
|
|
};
|
|
|
|
int __init pcie_bandwidth_notification_init(void)
|
|
{
|
|
return pcie_port_service_register(&pcie_bandwidth_notification_driver);
|
|
}
|