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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 4/4 v2] PCI: document the change
Complete the hotplug ABI document, and add SR-IOV HOWTO.
Signed-off-by: Yu Zhao <yu.zhao@xxxxxxxxx>
Signed-off-by: Eddie Dong <eddie.dong@xxxxxxxxx>
---
Documentation/ABI/testing/sysfs-bus-pci | 67 ++++++++++++
Documentation/DocBook/kernel-api.tmpl | 3 +
Documentation/PCI/pci-iov-howto.txt | 177 +++++++++++++++++++++++++++++++
3 files changed, 247 insertions(+), 0 deletions(-)
create mode 100644 Documentation/PCI/pci-iov-howto.txt
diff --git a/Documentation/ABI/testing/sysfs-bus-pci
b/Documentation/ABI/testing/sysfs-bus-pci
index ceddcff..374e87b 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -9,3 +9,70 @@ Description:
that some devices may have malformatted data. If the
underlying VPD has a writable section then the
corresponding section of this file will be writable.
+
+What: /sys/bus/pci/slots/.../power
+Date: Unknown
+Contact: linux-pci@xxxxxxxxxxxxxxx
+Description:
+ This file will appear when PCI hotplug is enabled and
+ the hotplug driver supports this operation.
+ It indicates power status of a slot, and could be written
+ to enable or disable the slot.
+
+What: /sys/bus/pci/slots/.../attention
+Date: Unknown
+Contact: linux-pci@xxxxxxxxxxxxxxx
+Description:
+ This file will appear when PCI hotplug is enabled and
+ the hotplug driver supports this operation.
+ It indicates attention LED status of a slot, and could
+ be written to set the LED status.
+
+What: /sys/bus/pci/slots/.../latch
+Date: Unknown
+Contact: linux-pci@xxxxxxxxxxxxxxx
+Description:
+ This file will appear when PCI hotplug is enabled and
+ the hotplug driver supports this operation.
+ It indicates latch status of a slot.
+
+What: /sys/bus/pci/slots/.../adapter
+Date: Unknown
+Contact: linux-pci@xxxxxxxxxxxxxxx
+Description:
+ This file will appear when PCI hotplug is enabled and
+ the hotplug driver supports this operation.
+ It indicates presence of the adapter.
+
+What: /sys/bus/pci/slots/.../max_bus_speed
+Date: Unknown
+Contact: linux-pci@xxxxxxxxxxxxxxx
+Description:
+ This file will appear when PCI hotplug is enabled and
+ the hotplug driver supports this operation.
+ It indicates max bus speed of a slot.
+
+What: /sys/bus/pci/slots/.../cur_bus_speed
+Date: Unknown
+Contact: linux-pci@xxxxxxxxxxxxxxx
+Description:
+ This file will appear when PCI hotplug is enabled and
+ the hotplug driver supports this operation.
+ It indicates current bus speed of a slot.
+
+What: /sys/bus/pci/slots/.../test
+Date: Unknown
+Contact: linux-pci@xxxxxxxxxxxxxxx
+Description:
+ This file will appear when PCI hotplug is enabled and
+ the hotplug driver supports this operation.
+ It triggers adapter hardware test upon writing.
+
+What: /sys/bus/pci/slots/.../param
+Date: August 2008
+Contact: linux-pci@xxxxxxxxxxxxxxx
+Description:
+ This file will appear when PCI hotplug is enabled and
+ the hotplug driver supports this operation.
+ It holds device specific parameters, and could be written
+ to configure the adapter in a slot.
diff --git a/Documentation/DocBook/kernel-api.tmpl
b/Documentation/DocBook/kernel-api.tmpl
index b7b1482..36273af 100644
--- a/Documentation/DocBook/kernel-api.tmpl
+++ b/Documentation/DocBook/kernel-api.tmpl
@@ -239,6 +239,7 @@ X!Ekernel/module.c
</sect1>
<sect1><title>PCI Support Library</title>
+!Iinclude/linux/pci.h
!Edrivers/pci/pci.c
!Edrivers/pci/pci-driver.c
!Edrivers/pci/remove.c
@@ -251,6 +252,8 @@ X!Edrivers/pci/hotplug.c
-->
!Edrivers/pci/probe.c
!Edrivers/pci/rom.c
+!Edrivers/pci/ari.c
+!Edrivers/pci/iov.c
</sect1>
<sect1><title>PCI Hotplug Support Library</title>
!Edrivers/pci/hotplug/pci_hotplug_core.c
diff --git a/Documentation/PCI/pci-iov-howto.txt
b/Documentation/PCI/pci-iov-howto.txt
new file mode 100644
index 0000000..147e80f
--- /dev/null
+++ b/Documentation/PCI/pci-iov-howto.txt
@@ -0,0 +1,177 @@
+ PCI Express Single Root I/O Virtualization HOWTO
+ Copyright (C) 2008 Intel Corporation
+ Yu Zhao <yu.zhao@xxxxxxxxx>
+
+
+1. Overview
+
+1.1 What is SR-IOV
+
+Single Root I/O Virtualization (SR-IOV) is a PCI Express Extended
+capability which makes one physical device appear as multiple virtual
+devices. The physical device is referred to as Physical Function while
+the virtual devices are referred to as Virtual Functions. Allocation
+of Virtual Functions can be dynamically controlled by Physical Function
+via registers encapsulated in the capability. By default, this feature
+is not enabled and the Physical Function behaves as traditional PCIe
+device. Once it's turned on, each Virtual Function's PCI configuration
+space can be accessed by its own Bus, Device and Function Number (Routing
+ID). And each Virtual Function also has PCI Memory Space, which is used
+to map its register set. Virtual Function device driver operates on the
+register set so it can be functional and appear as a real existing PCI
+device.
+
+1.2 What is ARI
+
+Alternative Routing-ID Interpretation (ARI) allows a PCI Express Endpoint
+to use its device number field as part of function number. Traditionally,
+an Endpoint can only have 8 functions, and the device number of all
+Endpoints is zero. With ARI enabled, an Endpoint can have up to 256
+functions by using device number in conjunction with function number to
+indicate a function in the device. This is almost transparent to the Linux
+kernel because the Linux kernel still can use 8-bit bus number field plus
+8-bit devfn number field to locate a function. ARI is managed via the ARI
+Forwarding bit in the Device Capabilities 2 register of the PCI Express
+Capability on the Root Port or the Downstream Port and a new ARI Capability
+on the Endpoint.
+
+
+2. User Guide
+
+2.1 How can I manage SR-IOV
+
+If a device supports SR-IOV, then there should be some entires under
+/sys/bus/pci/slots/. The names of the entires are XXXX:BB:DD.F-iov-NNNN,
+where the first part (XXXX:BB:DD.F) is the domain, bus, device and function
+number of the device, and the third part (NNNN) is the index of a Virtual
+Function. There are three files under the entry: power, param and address.
+ - Writing 1 to the "power" will enable the Virtual Function,
+ and 0 will disable the Virtual Function; Reading it will get
+ status of the Virtual Function.
+ - Reading the "address" will get the bus, device and function
+ number of the Virtual Function.
+ - The "param" is the device specific parameters which may be
+ used by the Physical or Virtual Functions drivers.
+
+2.2 How can I use Virtual Functions
+
+Virtual Functions is treated as hot-plugged PCI devices in the kernel,
+so they should be able to work in the same way as real PCI devices.
+NOTE: Virtual Function device driver must be loaded to make it work.
+
+
+3. Developer Guide
+
+3.1 SR-IOV APIs
+
+To enable SR-IOV, Physical Function device driver needs to call:
+ int pci_iov_enable(struct pci_dev *dev,
+ int (*cb)(struct pci_dev *, int, int, char *))
+The pointer to the callback function could be NULL if Physical Function
+wants to ignore the events.
+
+To disable SR-IOV, Physical Function device driver needs to call:
+ void pci_iov_disable(struct pci_dev *dev)
+
+NOTE: these two functions sleeps 1 second waiting on hardware transaction
+completion according to SR-IOV specification.
+
+3.2 Usage example
+
+Following piece of code illustrates the usage of APIs above.
+
+static int callback(struct pci_dev *dev, int event, int arg, char *param)
+{
+ int err;
+
+ switch (event) {
+ case PCI_IOV_VF_ENABLE:
+ /*
+ * request to enable a Virtual Function, setup hardware
+ * resource to this Virtual Function if needed.
+ */
+ break;
+ case PCI_IOV_VF_DISABLE:
+ /*
+ * a Virtual Function has been disabled, reclaim hardware
+ * resource if needed.
+ */
+ break;
+ case PCI_IOV_VF_SETPARAM:
+ /*
+ * parameter of a Virtual Function has been changed, take
+ * corresponding actions if needed.
+ */
+ break;
+ case PCI_IOV_VF_GETPARAM:
+ /*
+ * return the parameters of a Virtual Function if any.
+ */
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return err;
+}
+
+static int __devinit dev_probe(struct pci_dev *dev,
+ const struct pci_device_id *id)
+{
+ int err;
+
+ ...
+
+ err = pci_iov_enable(dev, callback);
+ if (err)
+ return err;
+
+ ...
+}
+
+static void __devexit dev_remove(struct pci_dev *dev)
+{
+ ...
+
+ pci_iov_disable(dev);
+
+ ...
+}
+
+#ifdef CONFIG_PM
+/*
+ * If the device supports the power management, then the SR-IOV
+ * may be disabled before the adapter goes to sleep, because
+ * Virtual Functions may not work when the adapter is in the\
+ * power-saving mode.
+ * The SR-IOV can be enabled again after the adapter wakes up.
+ */
+static int dev_suspend(struct pci_dev *dev, pm_message_t state)
+{
+ ...
+
+ pci_iov_disable(dev);
+
+ ...
+}
+
+static int dev_resume(struct pci_dev *dev)
+{
+ ...
+
+ pci_iov_enable(dev, nvfs, callback);
+
+ ...
+}
+#endif
+
+static struct pci_driver dev_driver = {
+ .name = "SR-IOV PF driver",
+ .id_table = dev_id_table,
+ .probe = dev_probe,
+ .remove = __devexit_p(dev_remove),
+#ifdef CONFIG_PM
+ .suspend = dev_suspend,
+ .resume = dev_resume,
+#endif
+};
--
1.5.6.4
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