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Diffstat (limited to 'Documentation/networking/device_drivers/google/gve.rst')
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diff --git a/Documentation/networking/device_drivers/google/gve.rst b/Documentation/networking/device_drivers/google/gve.rst deleted file mode 100644 index 793693cef6e3..000000000000 --- a/Documentation/networking/device_drivers/google/gve.rst +++ /dev/null @@ -1,123 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0+ - -============================================================== -Linux kernel driver for Compute Engine Virtual Ethernet (gve): -============================================================== - -Supported Hardware -=================== -The GVE driver binds to a single PCI device id used by the virtual -Ethernet device found in some Compute Engine VMs. - -+--------------+----------+---------+ -|Field | Value | Comments| -+==============+==========+=========+ -|Vendor ID | `0x1AE0` | Google | -+--------------+----------+---------+ -|Device ID | `0x0042` | | -+--------------+----------+---------+ -|Sub-vendor ID | `0x1AE0` | Google | -+--------------+----------+---------+ -|Sub-device ID | `0x0058` | | -+--------------+----------+---------+ -|Revision ID | `0x0` | | -+--------------+----------+---------+ -|Device Class | `0x200` | Ethernet| -+--------------+----------+---------+ - -PCI Bars -======== -The gVNIC PCI device exposes three 32-bit memory BARS: -- Bar0 - Device configuration and status registers. -- Bar1 - MSI-X vector table -- Bar2 - IRQ, RX and TX doorbells - -Device Interactions -=================== -The driver interacts with the device in the following ways: - - Registers - - A block of MMIO registers - - See gve_register.h for more detail - - Admin Queue - - See description below - - Reset - - At any time the device can be reset - - Interrupts - - See supported interrupts below - - Transmit and Receive Queues - - See description below - -Registers ---------- -All registers are MMIO and big endian. - -The registers are used for initializing and configuring the device as well as -querying device status in response to management interrupts. - -Admin Queue (AQ) ----------------- -The Admin Queue is a PAGE_SIZE memory block, treated as an array of AQ -commands, used by the driver to issue commands to the device and set up -resources.The driver and the device maintain a count of how many commands -have been submitted and executed. To issue AQ commands, the driver must do -the following (with proper locking): - -1) Copy new commands into next available slots in the AQ array -2) Increment its counter by he number of new commands -3) Write the counter into the GVE_ADMIN_QUEUE_DOORBELL register -4) Poll the ADMIN_QUEUE_EVENT_COUNTER register until it equals - the value written to the doorbell, or until a timeout. - -The device will update the status field in each AQ command reported as -executed through the ADMIN_QUEUE_EVENT_COUNTER register. - -Device Resets -------------- -A device reset is triggered by writing 0x0 to the AQ PFN register. -This causes the device to release all resources allocated by the -driver, including the AQ itself. - -Interrupts ----------- -The following interrupts are supported by the driver: - -Management Interrupt -~~~~~~~~~~~~~~~~~~~~ -The management interrupt is used by the device to tell the driver to -look at the GVE_DEVICE_STATUS register. - -The handler for the management irq simply queues the service task in -the workqueue to check the register and acks the irq. - -Notification Block Interrupts -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -The notification block interrupts are used to tell the driver to poll -the queues associated with that interrupt. - -The handler for these irqs schedule the napi for that block to run -and poll the queues. - -Traffic Queues --------------- -gVNIC's queues are composed of a descriptor ring and a buffer and are -assigned to a notification block. - -The descriptor rings are power-of-two-sized ring buffers consisting of -fixed-size descriptors. They advance their head pointer using a __be32 -doorbell located in Bar2. The tail pointers are advanced by consuming -descriptors in-order and updating a __be32 counter. Both the doorbell -and the counter overflow to zero. - -Each queue's buffers must be registered in advance with the device as a -queue page list, and packet data can only be put in those pages. - -Transmit -~~~~~~~~ -gve maps the buffers for transmit rings into a FIFO and copies the packets -into the FIFO before sending them to the NIC. - -Receive -~~~~~~~ -The buffers for receive rings are put into a data ring that is the same -length as the descriptor ring and the head and tail pointers advance over -the rings together. |