docs: networking: reorganize driver documentation again

Organize driver documentation by device type. Most documents
have fairly verbose yet uninformative names, so let users
first select a well defined device type, and then search for
a particular driver.

While at it rename the section from Vendor drivers to
Hardware drivers. This seems more accurate, besides people
sometimes refer to out-of-tree drivers as vendor drivers.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 123 insertions, 0 deletions

diff --git a/Documentation/networking/device_drivers/ethernet/google/gve.rst b/Documentation/networking/device_drivers/ethernet/google/gve.rst
new file mode 100644
index 000000000000..793693cef6e3
--- /dev/null
+++ b/Documentation/networking/device_drivers/ethernet/google/gve.rst
@@ -0,0 +1,123 @@
+.. 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.