Changes since v1:
* Layer on top of the pcie port service drivers, instead of hotplug service.
This patch needs to be applied on top of:
PCI: Add missing include to drivers/pci.h
Anticipated FAQ:
Q: Why is this unconditionally compiled in?
A: The symmetrical check in pci probe() is also always compiled in.
Q: Why call module_init() instead of adding a call in pcie_init_services() ?
A: A call in pcie_init_services() also requires a prototype in portdrv.h, a
non-static implementation in bw_notification.c. Using module_init() is
functionally equivalent, and takes less code.
Q: Why print only on degraded links and not when a link is back to full speed?
For symmetry with PCI probe(). Although I see a benefit in conveying that a
link is back to full speed, I expect this to be extremely rare. Secondary bus
reset is usually needed to retrain at full bandwidth.
drivers/pci/pcie/Makefile | 1 +
drivers/pci/pcie/bw_notification.c | 107 +++++++++++++++++++++++++++++
drivers/pci/pcie/portdrv.h | 4 +-
drivers/pci/pcie/portdrv_core.c | 14 ++--
4 files changed, 121 insertions(+), 5 deletions(-)
create mode 100644 drivers/pci/pcie/bw_notification.c
diff --git a/drivers/pci/pcie/Makefile b/drivers/pci/pcie/Makefile
index ab514083d5d4..f1d7bc1e5efa 100644
--- a/drivers/pci/pcie/Makefile
+++ b/drivers/pci/pcie/Makefile
@@ -3,6 +3,7 @@
# Makefile for PCI Express features and port driver
pcieportdrv-y := portdrv_core.o portdrv_pci.o err.o
+pcieportdrv-y += bw_notification.o
obj-$(CONFIG_PCIEPORTBUS) += pcieportdrv.o
diff --git a/drivers/pci/pcie/bw_notification.c b/drivers/pci/pcie/bw_notification.c
new file mode 100644
index 000000000000..64391ea9a172
--- /dev/null
+++ b/drivers/pci/pcie/bw_notification.c
@@ -0,0 +1,107 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * PCI Express Bandwidth notification services driver
+ * Author: Alexandru Gagniuc <mr.nuke.me@xxxxxxxxx>
+ *
+ * Copyright (C) 2018, Dell Inc
+ *
+ * The PCIe 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 <linux/module.h>
+
+#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_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;
+ struct pci_dev *dev;
+ 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 (!events || ret != PCIBIOS_SUCCESSFUL)
+ return IRQ_NONE;
+
+ /* Print status from upstream link partner, not this downstream port. */
+ list_for_each_entry(dev, &port->subordinate->devices, bus_list)
+ __pcie_print_link_status(dev, false);
+
+ pcie_capability_write_word(port, PCI_EXP_LNKSTA, events);
+ 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 = devm_request_irq(&srv->device, srv->irq, pcie_bw_notification_irq,
+ 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);
+}
+
+static struct pcie_port_service_driver pcie_bandwidth_notification_driver = {
+ .name = "pcie_bw_notification",
+ .port_type = PCI_EXP_TYPE_DOWNSTREAM,
+ .service = PCIE_PORT_SERVICE_BwNOTIF,
+ .probe = pcie_bandwidth_notification_probe,
+ .remove = pcie_bandwidth_notification_remove,
+};
+
+static int __init pcie_bandwidth_notification_service_init(void)
+{
+ return pcie_port_service_register(&pcie_bandwidth_notification_driver);
+}
+
+module_init(pcie_bandwidth_notification_service_init);
diff --git a/drivers/pci/pcie/portdrv.h b/drivers/pci/pcie/portdrv.h
index e495f04394d0..46652469ffaa 100644
--- a/drivers/pci/pcie/portdrv.h
+++ b/drivers/pci/pcie/portdrv.h
@@ -20,8 +20,10 @@
#define PCIE_PORT_SERVICE_HP (1 << PCIE_PORT_SERVICE_HP_SHIFT)
#define PCIE_PORT_SERVICE_DPC_SHIFT 3 /* Downstream Port Containment */
#define PCIE_PORT_SERVICE_DPC (1 << PCIE_PORT_SERVICE_DPC_SHIFT)
+#define PCIE_PORT_SERVICE_BWNOTIF_SHIFT 4 /* Bandwidth notification */
+#define PCIE_PORT_SERVICE_BwNOTIF (1 << PCIE_PORT_SERVICE_BWNOTIF_SHIFT)
-#define PCIE_PORT_DEVICE_MAXSERVICES 4
+#define PCIE_PORT_DEVICE_MAXSERVICES 5
#ifdef CONFIG_PCIEAER
int pcie_aer_init(void);
diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c
index f458ac9cb70c..86455ff7ced9 100644
--- a/drivers/pci/pcie/portdrv_core.c
+++ b/drivers/pci/pcie/portdrv_core.c
@@ -99,7 +99,7 @@ static int pcie_message_numbers(struct pci_dev *dev, int mask,
*/
static int pcie_port_enable_irq_vec(struct pci_dev *dev, int *irqs, int mask)
{
- int nr_entries, nvec;
+ int nr_entries, nvec, pcie_irq;
u32 pme = 0, aer = 0, dpc = 0;
/* Allocate the maximum possible number of MSI/MSI-X vectors */
@@ -136,9 +136,12 @@ static int pcie_port_enable_irq_vec(struct pci_dev *dev, int *irqs, int mask)
}
/* PME and hotplug share an MSI/MSI-X vector */
- if (mask & (PCIE_PORT_SERVICE_PME | PCIE_PORT_SERVICE_HP)) {
- irqs[PCIE_PORT_SERVICE_PME_SHIFT] = pci_irq_vector(dev, pme);
- irqs[PCIE_PORT_SERVICE_HP_SHIFT] = pci_irq_vector(dev, pme);
+ if (mask & (PCIE_PORT_SERVICE_PME | PCIE_PORT_SERVICE_HP |
+ PCIE_PORT_SERVICE_BwNOTIF)) {
+ pcie_irq = pci_irq_vector(dev, pme);
+ irqs[PCIE_PORT_SERVICE_PME_SHIFT] = pcie_irq;
+ irqs[PCIE_PORT_SERVICE_HP_SHIFT] = pcie_irq;
+ irqs[PCIE_PORT_SERVICE_BWNOTIF_SHIFT] = pcie_irq;
}
if (mask & PCIE_PORT_SERVICE_AER)
@@ -250,6 +253,9 @@ static int get_port_device_capability(struct pci_dev *dev)
pci_aer_available() && services & PCIE_PORT_SERVICE_AER)
services |= PCIE_PORT_SERVICE_DPC;
+ if (pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM)
+ services |= PCIE_PORT_SERVICE_BwNOTIF;
+
return services;
}
