ARC: [DeviceTree] Basic support

This is minimal infrastructure needed for devicetree work.
It uses an a sample "skeleton" devicetree - embedded in kernel image -
to print the board, manufacturer by parsing the top-level "compatible"
string.

As of now we don't need any additional "board" specific "machine_desc".

TODO: support interpreting the command line as boot-loader passed dtb

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: devicetree-discuss@lists.ozlabs.org
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: James Hogan <james.hogan@imgtec.com>
Reviewed-by: Rob Herring <rob.herring@calxeda.com>
Reviewed-by: James Hogan <james.hogan@imgtec.com>

3 files changed, 74 insertions, 0 deletions

diff --git a/arch/arc/kernel/Makefile b/arch/arc/kernel/Makefile
index 6d834312f755..c9ec0662a4ec 100644
--- a/arch/arc/kernel/Makefile
+++ b/arch/arc/kernel/Makefile
@@ -7,6 +7,7 @@
 
 obj-y   := arcksyms.o setup.o irq.o time.o reset.o ptrace.o entry.o process.o
 obj-y   += signal.o traps.o sys.o troubleshoot.o stacktrace.o clk.o
+obj-y   += devtree.o
 
 obj-$(CONFIG_ARC_FPU_SAVE_RESTORE)      += fpu.o
 CFLAGS_fpu.o   += -mdpfp
diff --git a/arch/arc/kernel/devtree.c b/arch/arc/kernel/devtree.c
new file mode 100644
index 000000000000..48e157efad15
--- /dev/null
+++ b/arch/arc/kernel/devtree.c
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * Based on reduced version of METAG
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+
+#include <linux/init.h>
+#include <linux/reboot.h>
+#include <linux/memblock.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <asm/prom.h>
+
+/* called from unflatten_device_tree() to bootstrap devicetree itself */
+void * __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
+{
+        return __va(memblock_alloc(size, align));
+}
+
+/**
+ * setup_machine_fdt - Machine setup when an dtb was passed to the kernel
+ * @dt:         virtual address pointer to dt blob
+ *
+ * If a dtb was passed to the kernel, then use it to choose the correct
+ * machine_desc and to setup the system.
+ */
+int __init setup_machine_fdt(void *dt)
+{
+        struct boot_param_header *devtree = dt;
+        unsigned long dt_root;
+        char *model, *compat;
+        char manufacturer[16];
+
+        /* check device tree validity */
+        if (be32_to_cpu(devtree->magic) != OF_DT_HEADER)
+                return 1;
+
+        /* Search the mdescs for the 'best' compatible value match */
+        initial_boot_params = devtree;
+        dt_root = of_get_flat_dt_root();
+
+        /* compat = "<manufacturer>,<model>" */
+        compat = of_get_flat_dt_prop(dt_root, "compatible", NULL);
+        if (!compat)
+                compat = "<unknown>";
+
+        model = strchr(compat, ',');
+        if (model)
+                model++;
+
+        strlcpy(manufacturer, compat, model ? model - compat : strlen(compat));
+
+        pr_info("Board \"%s\" from %s (Manufacturer)\n", model, manufacturer);
+
+        /* Retrieve various information from the /chosen node */
+        of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
+
+        return 0;
+}
diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
index 82ac20603398..27aebd6d9513 100644
--- a/arch/arc/kernel/setup.c
+++ b/arch/arc/kernel/setup.c
@@ -13,6 +13,8 @@
 #include <linux/console.h>
 #include <linux/module.h>
 #include <linux/cpu.h>
+#include <linux/of_fdt.h>
+#include <asm/sections.h>
 #include <asm/arcregs.h>
 #include <asm/tlb.h>
 #include <asm/cache.h>
@@ -20,6 +22,7 @@
 #include <asm/page.h>
 #include <asm/irq.h>
 #include <asm/arcregs.h>
+#include <asm/prom.h>
 
 #define FIX_PTR(x)  __asm__ __volatile__(";" : "+r"(x))
 
@@ -57,6 +60,8 @@ void __init __attribute__((weak)) arc_platform_early_init(void)
 
 void __init setup_arch(char **cmdline_p)
 {
+        int rc;
+
 #ifdef CONFIG_CMDLINE_UBOOT
         /* Make sure that a whitespace is inserted before */
         strlcat(command_line, " ", sizeof(command_line));
@@ -71,6 +76,8 @@ void __init setup_arch(char **cmdline_p)
         strlcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
         *cmdline_p = command_line;
 
+        rc = setup_machine_fdt(__dtb_start);
+
         /* To force early parsing of things like mem=xxx */
         parse_early_param();
 
@@ -81,6 +88,8 @@ void __init setup_arch(char **cmdline_p)
 
         setup_arch_memory();
 
+        unflatten_device_tree();
+
         /* Can be issue if someone passes cmd line arg "ro"
          * But that is unlikely so keeping it as it is
          */