ST SPEAr: PCIE gadget suppport

This is a configurable gadget.  can be configured by configfs interface.
Any IP available at PCIE bus can be programmed to be used by host
controller.It supoorts both INTX and MSI.

By default, the gadget is configured for INTX and SYSRAM1 is mapped to
BAR0 with size 0x1000

Signed-off-by: Pratyush Anand <pratyush.anand@st.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Viresh Kumar <viresh.kumar@st.com>
Cc: Shiraz Hashim <shiraz.hashim@st.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 130 insertions, 0 deletions

diff --git a/Documentation/misc-devices/spear-pcie-gadget.txt b/Documentation/misc-devices/spear-pcie-gadget.txt
new file mode 100644
index 000000000000..02c13ef5e908
--- /dev/null
+++ b/Documentation/misc-devices/spear-pcie-gadget.txt
@@ -0,0 +1,130 @@
+Spear PCIe Gadget Driver:
+
+Author
+=============
+Pratyush Anand (pratyush.anand@st.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 -