sh: mach-sdk7786: Probe system FPGA area mapping.

This implements dynamic probing for the system FPGA. The system reset
controller contains a fixed magic read word in order to identify the
FPGA. This just utilizes a simple loop that scans across all of the fixed
physical areas (area 0 through area 6) to locate the FPGA.

The FPGA also contains register information detailing the area mappings
and chip select settings for all of the other blocks, so this needs to be
done before we can set up anything else.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

3 files changed, 50 insertions, 4 deletions

diff --git a/arch/sh/boards/mach-sdk7786/fpga.c b/arch/sh/boards/mach-sdk7786/fpga.c
index 99f903c8b238..3e4ec66a0417 100644
--- a/arch/sh/boards/mach-sdk7786/fpga.c
+++ b/arch/sh/boards/mach-sdk7786/fpga.c
@@ -11,9 +11,44 @@
 #include <linux/io.h>
 #include <linux/bcd.h>
 #include <mach/fpga.h>
+#include <asm/sizes.h>
 
-#define FPGA_REGS_BASE  0x07fff800
-#define FPGA_REGS_SIZE  0x490
+#define FPGA_REGS_OFFSET        0x03fff800
+#define FPGA_REGS_SIZE          0x490
+
+/*
+ * The FPGA can be mapped in any of the generally available areas,
+ * so we attempt to scan for it using the fixed SRSTR read magic.
+ *
+ * Once the FPGA is located, the rest of the mapping data for the other
+ * components can be determined dynamically from its section mapping
+ * registers.
+ */
+static void __iomem *sdk7786_fpga_probe(void)
+{
+        unsigned long area;
+        void __iomem *base;
+
+        /*
+         * Iterate over all of the areas where the FPGA could be mapped.
+         * The possible range is anywhere from area 0 through 6, area 7
+         * is reserved.
+         */
+        for (area = PA_AREA0; area < PA_AREA7; area += SZ_64M) {
+                base = ioremap_nocache(area + FPGA_REGS_OFFSET, FPGA_REGS_SIZE);
+                if (!base) {
+                        /* Failed to remap this area, move along. */
+                        continue;
+                }
+
+                if (ioread16(base + SRSTR) == SRSTR_MAGIC)
+                        return base;    /* Found it! */
+
+                iounmap(base);
+        }
+
+        return NULL;
+}
 
 void __iomem *sdk7786_fpga_base;
 
@@ -21,9 +56,9 @@ void __init sdk7786_fpga_init(void)
 {
         u16 version, date;
 
-        sdk7786_fpga_base = ioremap_nocache(FPGA_REGS_BASE, FPGA_REGS_SIZE);
+        sdk7786_fpga_base = sdk7786_fpga_probe();
         if (unlikely(!sdk7786_fpga_base)) {
-                panic("FPGA remapping failed.\n");
+                panic("FPGA detection failed.\n");
                 return;
         }
 
diff --git a/arch/sh/include/cpu-sh4/cpu/addrspace.h b/arch/sh/include/cpu-sh4/cpu/addrspace.h
index a3fa733c1c7d..d51da25da72c 100644
--- a/arch/sh/include/cpu-sh4/cpu/addrspace.h
+++ b/arch/sh/include/cpu-sh4/cpu/addrspace.h
@@ -28,6 +28,15 @@
 #define P4SEG_TLB_DATA  0xf7000000
 #define P4SEG_REG_BASE  0xff000000
 
+#define PA_AREA0        0x00000000
+#define PA_AREA1        0x04000000
+#define PA_AREA2        0x08000000
+#define PA_AREA3        0x0c000000
+#define PA_AREA4        0x10000000
+#define PA_AREA5        0x14000000
+#define PA_AREA6        0x18000000
+#define PA_AREA7        0x1c000000
+
 #define PA_AREA5_IO     0xb4000000      /* Area 5 IO Memory */
 #define PA_AREA6_IO     0xb8000000      /* Area 6 IO Memory */
 
diff --git a/arch/sh/include/mach-sdk7786/mach/fpga.h b/arch/sh/include/mach-sdk7786/mach/fpga.h
index a85d9853d34f..2120d67dec70 100644
--- a/arch/sh/include/mach-sdk7786/mach/fpga.h
+++ b/arch/sh/include/mach-sdk7786/mach/fpga.h
@@ -6,6 +6,8 @@
 #include <linux/bitops.h>
 
 #define SRSTR           0x000
+#define  SRSTR_MAGIC    0x1971  /* Fixed magical read value */
+
 #define INTASR          0x010
 #define INTAMR          0x020
 #define MODSWR          0x030