docs: misc-devices/spear-pcie-gadget.txt: convert to ReST

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Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/4f8e129a93d04426ad7dd51f109725c48158a46d.1592203650.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

1 files changed, 170 insertions, 0 deletions

diff --git a/Documentation/misc-devices/spear-pcie-gadget.rst b/Documentation/misc-devices/spear-pcie-gadget.rst
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+.. SPDX-License-Identifier: GPL-2.0
+
+========================
+Spear PCIe Gadget Driver
+========================
+
+Author
+======
+Pratyush Anand (pratyush.anand@gmail.com)
+
+Location
+========
+driver/misc/spear13xx_pcie_gadget.c
+
+Supported Chip:
+===============
+SPEAr1300
+SPEAr1310
+
+Menuconfig option:
+==================
+Device Drivers
+	Misc devices
+		PCIe gadget support for SPEAr13XX platform
+
+purpose
+=======
+This driver has several nodes which can be read/written by configfs interface.
+Its main purpose is to configure selected dual mode PCIe controller as device
+and then program its various registers to configure it as a particular device
+type. This driver can be used to show spear's PCIe device capability.
+
+Description of different nodes:
+===============================
+
+read behavior of nodes:
+-----------------------
+
+=============== ==============================================================
+link 		gives ltssm status.
+int_type 	type of supported interrupt
+no_of_msi 	zero if MSI is not enabled by host. A positive value is the
+		number of MSI vector granted.
+vendor_id	returns programmed vendor id (hex)
+device_id	returns programmed device id(hex)
+bar0_size:	returns size of bar0 in hex.
+bar0_address	returns address of bar0 mapped area in hex.
+bar0_rw_offset	returns offset of bar0 for which bar0_data will return value.
+bar0_data	returns data at bar0_rw_offset.
+=============== ==============================================================
+
+write behavior of nodes:
+------------------------
+
+=============== ================================================================
+link 		write UP to enable ltsmm DOWN to disable
+int_type	write interrupt type to be configured and (int_type could be
+		INTA, MSI or NO_INT). Select MSI only when you have programmed
+		no_of_msi node.
+no_of_msi	number of MSI vector needed.
+inta		write 1 to assert INTA and 0 to de-assert.
+send_msi	write MSI vector to be sent.
+vendor_id	write vendor id(hex) to be programmed.
+device_id	write device id(hex) to be programmed.
+bar0_size	write size of bar0 in hex. default bar0 size is 1000 (hex)
+		bytes.
+bar0_address	write	address of bar0 mapped area in hex. (default mapping of
+		bar0 is SYSRAM1(E0800000). Always program bar size before bar
+		address. Kernel might modify bar size and address for alignment,
+		so read back bar size and address after writing to cross check.
+bar0_rw_offset	write offset of bar0 for which	bar0_data will write value.
+bar0_data	write data to be written at bar0_rw_offset.
+=============== ================================================================
+
+Node programming example
+========================
+
+Program all PCIe registers in such a way that when this device is connected
+to the PCIe host, then host sees this device as 1MB RAM.
+
+::
+
+    #mount -t configfs none /Config
+
+For nth PCIe Device Controller::
+
+    # cd /config/pcie_gadget.n/
+
+Now you have all the nodes in this directory.
+program vendor id as 0x104a::
+
+    # echo 104A >> vendor_id
+
+program device id as 0xCD80::
+
+    # echo CD80 >> device_id
+
+program BAR0 size as 1MB::
+
+    # echo 100000 >> bar0_size
+
+check for programmed bar0 size::
+
+    # cat bar0_size
+
+Program BAR0 Address as DDR (0x2100000). This is the physical address of
+memory, which is to be made visible to PCIe host. Similarly any other peripheral
+can also be made visible to PCIe host. E.g., if you program base address of UART
+as BAR0 address then when this device will be connected to a host, it will be
+visible as UART.
+
+::
+
+    # echo 2100000 >> bar0_address
+
+program interrupt type : INTA::
+
+    # echo INTA >> int_type
+
+go for link up now::
+
+    # echo UP >> link
+
+It will have to be insured that, once link up is done on gadget, then only host
+is initialized and start to search PCIe devices on its port.
+
+::
+
+    /*wait till link is up*/
+    # cat link
+
+Wait till it returns UP.
+
+To assert INTA::
+
+    # echo 1 >> inta
+
+To de-assert INTA::
+
+    # echo 0 >> inta
+
+if MSI is to be used as interrupt, program no of msi vector needed (say4)::
+
+    # echo 4 >> no_of_msi
+
+select MSI as interrupt type::
+
+    # echo MSI >> int_type
+
+go for link up now::
+
+    # echo UP >> link
+
+wait till link is up::
+
+    # cat link
+
+An application can repetitively read this node till link is found UP. It can
+sleep between two read.
+
+wait till msi is enabled::
+
+    # cat no_of_msi
+
+Should return 4 (number of requested MSI vector)
+
+to send msi vector 2::
+
+    # echo 2 >> send_msi
+    # cd -