[PATCH v2 2/3] ARM: dts: socfpga: fpga bridges bindings docs

[atull]

From: Alan Tull <atull@xxxxxxxxxxxxxxxxxxxxx>

Add DTS binding documentation for the Altera FPGA bridges.

Signed-off-by: Alan Tull <atull@xxxxxxxxxxxxxxxxxxxxx>
---
 .../bindings/fpga/altera-fpga2sdram-bridge.txt     |   57 ++++++++++++++++++++
 .../bindings/fpga/altera-hps2fpga-bridge.txt       |   53 ++++++++++++++++++
 2 files changed, 110 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/fpga/altera-fpga2sdram-bridge.txt
 create mode 100644 Documentation/devicetree/bindings/fpga/altera-hps2fpga-bridge.txt

diff --git a/Documentation/devicetree/bindings/fpga/altera-fpga2sdram-bridge.txt b/Documentation/devicetree/bindings/fpga/altera-fpga2sdram-bridge.txt
new file mode 100644
index 0000000..cc8f522
--- /dev/null
+++ b/Documentation/devicetree/bindings/fpga/altera-fpga2sdram-bridge.txt
@@ -0,0 +1,57 @@
+Altera FPGA To SDRAM Bridge Driver
+
+This driver manages a bridge between an FPGA and the SDRAM used by an host
+processor system (HPS). The bridge contains a number read ports, write ports,
+and command ports.  Reconfiguring these ports requires that no SDRAM
+transactions occur during reconfiguration.  In other words, the code
+reconfiguring the ports cannot be run out of SDRAM nor can the FPGA access the
+SDRAM during the reconfiguration.  This driver does not support reconfiguring
+the ports.  Typcially, the ports are configured by code running out of onchip
+ram before Linux is started.
+
+This driver supports enabling and disabling of the configured ports all at
+once, which allows for safe reprogramming of the FPGA from user space, provided
+the new FPGA image uses the same port configuration. User space can enable or
+disable the bridge by writing a "1" or a "0", respectively, to its enable file
+under bridge's entry in /sys/class/fpga-bridge. Typically, one disables the
+bridges before reprogramming the FPGA.  Once the FPGA is reprogrammed, the
+bridges are reenabled.
+
+Required properties:
+
+ - compatible       : "altr,socfpga-fpga2sdram-bridge"
+
+ - read-ports-mask  : Bits 0 to 3 corresponds read ports 0 to 3. A bit set to 1
+                      indicates the corresponding read port should be enabled.
+
+ - write-ports-mask : Bits 0 to 3 corresponds write ports 0 to 3. A bit set
+                      to 1 indicates the corresponding write port should be
+                      enabled.
+
+ - cmd-ports-mask   : Bits 0 to 5 correspond to command ports 0 to 5. A bit set
+                      to 1 indicates the corresponding command port should be
+                      enabled.
+
+ - altr,sdr-syscon  : phandle of the sdr module
+
+Optional properties:
+
+ - label            : name that you want this bridge to show up as under
+                      /sys/class/fpga-bridge. Default is br<device#> if this is
+                      not specified.
+
+ - init-val         : 0 if driver should disable bridge at startup
+                      1 if driver should enable bridge at startup
+                      driver leaves bridge in current state if property not
+		      specified.
+
+Example:
+	fpga2sdram_br: fpgabridge@3 {
+		compatible = "altr,socfpga-fpga2sdram-bridge";
+		label = "fpga2sdram";
+		altr,sdr-syscon = <&sdr>;
+		read-ports-mask = <3>;
+		write-ports-mask = <3>;
+		cmd-ports-mask = <0xd>;
+		init-val = <0>;
+	};
diff --git a/Documentation/devicetree/bindings/fpga/altera-hps2fpga-bridge.txt b/Documentation/devicetree/bindings/fpga/altera-hps2fpga-bridge.txt
new file mode 100644
index 0000000..bc24a2e
--- /dev/null
+++ b/Documentation/devicetree/bindings/fpga/altera-hps2fpga-bridge.txt
@@ -0,0 +1,53 @@
+Altera FPGA/HPS Bridge Driver
+
+This driver manages a bridge between a FPGA and a host processor system (HPS).
+User space can enable or disable the bridge by writing a "1" or a "0",
+respectively, to its enable file under bridge's entry in
+/sys/class/fpga-bridge.  Typically, one disables the bridges before
+reprogramming the FPGA.  Once the FPGA is reprogrammed, the bridges are
+reenabled.
+
+Required properties:
+
+ - compatible     : should contain one of:
+                     "altr,socfpga-hps2fpga-bridge"
+                     "altr,socfpga-lwhps2fpga-bridge"
+                     "altr,socfpga-fpga2hps-bridge"
+
+ - clocks         : clocks used by this module
+
+ - altr,l3-syscon : phandle of the l3 interconnect module
+
+Optional properties:
+ - label          : name that you want this bridge to show up as under
+                    /sys/class/fpga-bridge.  Default is br<device#> if this is
+                    not specified.
+
+ - init-val       : 0 if driver should disable bridge at startup
+                    1 if driver should enable bridge at startup
+                    driver leaves bridge in current state if property not
+                    specified.
+
+Example:
+	hps_fpgabridge0: fpgabridge@0 {
+		compatible = "altr,socfpga-hps2fpga-bridge";
+		label = "hps2fpga";
+		altr,l3-syscon = <&l3regs>;
+		clocks = <&l4_main_clk>;
+		init-val = <1>;
+	};
+
+	hps_fpgabridge1: fpgabridge@1 {
+		compatible = "altr,socfpga-lwhps2fpga-bridge";
+		label = "lwhps2fpga";
+		altr,l3-syscon = <&l3regs>;
+		clocks = <&l4_main_clk>;
+		init-val = <0>;
+	};
+
+	hps_fpgabridge2: fpgabridge@2 {
+		compatible = "altr,socfpga-fpga2hps-bridge";
+		label = "fpga2hps";
+		altr,l3-syscon = <&l3regs>;
+		clocks = <&l4_main_clk>;
+	};
-- 
1.7.9.5

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