Documentation: PCI: Add specification for the *PCI test* function device

Add specification for the *PCI test* virtual function device. The endpoint
function driver and the host PCI driver should be created based on this
specification.
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Documentation/PCI/00-INDEX

@@ -16,3 +16,5 @@ endpoint/pci-endpoint.txt
 	- guide to add endpoint controller driver and endpoint function driver.
 endpoint/pci-endpoint-cfs.txt
 	- guide to use configfs to configure the PCI endpoint function.
+endpoint/pci-test-function.txt
+	- specification of *PCI test* function device.

Documentation/PCI/endpoint/pci-test-function.txt

+				PCI TEST
+		    Kishon Vijay Abraham I <kishon@ti.com>
+
+Traditionally PCI RC has always been validated by using standard
+PCI cards like ethernet PCI cards or USB PCI cards or SATA PCI cards.
+However with the addition of EP-core in linux kernel, it is possible
+to configure a PCI controller that can operate in EP mode to work as
+a test device.
+
+The PCI endpoint test device is a virtual device (defined in software)
+used to test the endpoint functionality and serve as a sample driver
+for other PCI endpoint devices (to use the EP framework).
+
+The PCI endpoint test device has the following registers:
+
+	1) PCI_ENDPOINT_TEST_MAGIC
+	2) PCI_ENDPOINT_TEST_COMMAND
+	3) PCI_ENDPOINT_TEST_STATUS
+	4) PCI_ENDPOINT_TEST_SRC_ADDR
+	5) PCI_ENDPOINT_TEST_DST_ADDR
+	6) PCI_ENDPOINT_TEST_SIZE
+	7) PCI_ENDPOINT_TEST_CHECKSUM
+
+*) PCI_ENDPOINT_TEST_MAGIC
+
+This register will be used to test BAR0. A known pattern will be written
+and read back from MAGIC register to verify BAR0.
+
+*) PCI_ENDPOINT_TEST_COMMAND:
+
+This register will be used by the host driver to indicate the function
+that the endpoint device must perform.
+
+Bitfield Description:
+  Bit 0		: raise legacy IRQ
+  Bit 1		: raise MSI IRQ
+  Bit 2 - 7	: MSI interrupt number
+  Bit 8		: read command (read data from RC buffer)
+  Bit 9		: write command (write data to RC buffer)
+  Bit 10	: copy command (copy data from one RC buffer to another
+		  RC buffer)
+
+*) PCI_ENDPOINT_TEST_STATUS
+
+This register reflects the status of the PCI endpoint device.
+
+Bitfield Description:
+  Bit 0		: read success
+  Bit 1		: read fail
+  Bit 2		: write success
+  Bit 3		: write fail
+  Bit 4		: copy success
+  Bit 5		: copy fail
+  Bit 6		: IRQ raised
+  Bit 7		: source address is invalid
+  Bit 8		: destination address is invalid
+
+*) PCI_ENDPOINT_TEST_SRC_ADDR
+
+This register contains the source address (RC buffer address) for the
+COPY/READ command.
+
+*) PCI_ENDPOINT_TEST_DST_ADDR
+
+This register contains the destination address (RC buffer address) for
+the COPY/WRITE command.