Supports Altera SOCFPGA bridges:
 * fpga2sdram
 * fpga2hps
 * hps2fpga
 * lwhps2fpga

Allows enabling/disabling the bridges through the FPGA
Bridge Framework API functions.

The fpga2sdram driver only supports enabling and disabling
of the ports that been configured early on.  This is due to
a hardware limitation where the read, write, and command
ports on the fpga2sdram bridge can only be reconfigured
while there are no transactions to the sdram, i.e. when
running out of OCRAM before the kernel boots.

Device tree property 'init-val' configures the driver to
enable or disable the bridge during probe.  If the property
does not exist, the driver will leave the bridge in its
current state.

Signed-off-by: Alan Tull <redacted>
Signed-off-by: Matthew Gerlach <redacted>
Signed-off-by: Dinh Nguyen <redacted>
---
v2:  Use resets instead of directly writing reset registers
v12: Bump version to align with simple-fpga-bus version
     Get rid of the sysfs interface
     fpga2sdram: get configuration stored in handoff register
v13: Remove unneeded WARN_ON
     Change property from init-val to bridge-enable
     Checkpatch cleanup
     Fix email address
v14: use module_platform_driver
     remove unused struct field and some #defines
     don't really need exclamation points on error msgs
     *const* struct fpga_bridge_ops
v15: No change in this patch for v15 of this patch set
v16: No change in this patch for v16 of this patch set
v17: No change to this patch for v17 of this patch set
v18: Eliminate need to specify reset names since only one reset
---
 drivers/fpga/Kconfig             |   7 ++
 drivers/fpga/Makefile            |   1 +
 drivers/fpga/altera-fpga2sdram.c | 174 ++++++++++++++++++++++++++++++++
 drivers/fpga/altera-hps2fpga.c   | 213 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 395 insertions(+)
 create mode 100644 drivers/fpga/altera-fpga2sdram.c
 create mode 100644 drivers/fpga/altera-hps2fpga.c

diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
index ec81e21..b346166 100644
--- a/drivers/fpga/Kconfig
+++ b/drivers/fpga/Kconfig

@@ -39,6 +39,13 @@ config FPGA_BRIDGE
          Say Y here if you want to support bridges connected between host
         processors and FPGAs or between FPGAs.

+config SOCFPGA_FPGA_BRIDGE
+       bool "Altera SoCFPGA FPGA Bridges"
+       depends on ARCH_SOCFPGA && FPGA_BRIDGE
+       help
+         Say Y to enable drivers for FPGA bridges for Altera SOCFPGA
+         devices.
+
 endif # FPGA

 endmenu

diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
index 8d746c3..e658436 100644
--- a/drivers/fpga/Makefile
+++ b/drivers/fpga/Makefile

@@ -11,6 +11,7 @@ obj-$(CONFIG_FPGA_MGR_ZYNQ_FPGA)      += zynq-fpga.o

 # FPGA Bridge Drivers
 obj-$(CONFIG_FPGA_BRIDGE)              += fpga-bridge.o
+obj-$(CONFIG_SOCFPGA_FPGA_BRIDGE)      += altera-hps2fpga.o altera-fpga2sdram.o

 # High Level Interfaces
 obj-$(CONFIG_FPGA_REGION)              += fpga-region.o

diff --git a/drivers/fpga/altera-fpga2sdram.c b/drivers/fpga/altera-fpga2sdram.c
new file mode 100644
index 0000000..91f4a40
--- /dev/null
+++ b/drivers/fpga/altera-fpga2sdram.c

@@ -0,0 +1,174 @@
+/*
+ * FPGA to SDRAM Bridge Driver for Altera SoCFPGA Devices
+ *
+ *  Copyright (C) 2013-2015 Altera Corporation, All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * This driver manages a bridge between an FPGA and the SDRAM used by the ARM
+ * host processor system (HPS).
+ *
+ * The bridge contains 4 read ports, 4 write ports, and 6 command ports.
+ * Reconfiguring these ports requires that no SDRAM transactions occur during
+ * reconfiguration.  The code reconfiguring the ports cannot run out of SDRAM
+ * nor can the FPGA access the SDRAM during reconfiguration.  This driver does
+ * not support reconfiguring the ports.  The ports are configured by code
+ * running out of on chip ram before Linux is started and the configuration
+ * is passed in a handoff register in the system manager.
+ *
+ * This driver supports enabling and disabling of the configured ports, which
+ * allows for safe reprogramming of the FPGA, assuming that the new FPGA image
+ * uses the same port configuration.  Bridges must be disabled before
+ * reprogramming the FPGA and re-enabled after the FPGA has been programmed.
+ */
+
+#include <linux/fpga/fpga-bridge.h>
+#include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h