ARM: EXYNOS: Avoid early use of of_machine_is_compatible()

The recent commit "ARM: EXYNOS: add support for EXYNOS5440 SoC" broke
support for exynos5250 because of_machine_is_compatible() was used too
early in the boot process.  It also probably meant that the exynos5440
failed to use the proper iotable.  Switch to use
of_flat_dt_is_compatible() in both of these cases.

The failure I was seeing in exynos5250 because of this was:
  Division by zero in kernel.
  [<80015ed4>] (unwind_backtrace+0x0/0xec) from [<8045c7a4>] (dump_stack+0x20/0x24)
  [<8045c7a4>] (dump_stack+0x20/0x24) from [<80012990>] (__div0+0x20/0x28)
  [<80012990>] (__div0+0x20/0x28) from [<8021ab04>] (Ldiv0_64+0x8/0x18)
  [<8021ab04>] (Ldiv0_64+0x8/0x18) from [<80068560>] (__clocksource_updatefreq_scale+0x54/0x134)
  [<80068560>] (__clocksource_updatefreq_scale+0x54/0x134) from [<8006865c>] (__clocksource_register_scale+0x1c/0x54)
  [<8006865c>] (__clocksource_register_scale+0x1c/0x54) from [<80612a18>] (exynos_timer_init+0x100/0x1e8)
  [<80612a18>] (exynos_timer_init+0x100/0x1e8) from [<8060d184>] (time_init+0x28/0x38)
  [<8060d184>] (time_init+0x28/0x38) from [<8060a754>] (start_kernel+0x1e0/0x3c8)
  [<8060a754>] (start_kernel+0x1e0/0x3c8) from [<40008078>] (0x40008078)
Signed-off-by: NDoug Anderson <dianders@chromium.org>
Acked-by: NKukjin Kim <kgene.kim@samsung.com>
[olofj: fixed two build errors, one missing include and one !CONFIG_OF failure]
Signed-off-by: NOlof Johansson <olof@lixom.net>

arch/arm/mach-exynos/common.c

@@ -18,6 +18,7 @@
 #include <linux/sched.h>
 #include <linux/serial_core.h>
 #include <linux/of.h>
+#include <linux/of_fdt.h>
 #include <linux/of_irq.h>
 #include <linux/export.h>
 #include <linux/irqdomain.h>
@@ -121,6 +122,7 @@ static struct map_desc exynos_iodesc[] __initdata = {
 	},
 };
 
+#ifdef CONFIG_ARCH_EXYNOS5
 static struct map_desc exynos5440_iodesc[] __initdata = {
 	{
 		.virtual	= (unsigned long)S5P_VA_CHIPID,
@@ -129,6 +131,7 @@ static struct map_desc exynos5440_iodesc[] __initdata = {
 		.type		= MT_DEVICE,
 	},
 };
+#endif
 
 static struct map_desc exynos4_iodesc[] __initdata = {
 	{
@@ -346,11 +349,19 @@ void __init exynos_init_late(void)
 
 void __init exynos_init_io(struct map_desc *mach_desc, int size)
 {
+	struct map_desc *iodesc = exynos_iodesc;
+	int iodesc_sz = ARRAY_SIZE(exynos_iodesc);
+#if defined(CONFIG_OF) && defined(CONFIG_ARCH_EXYNOS5)
+	unsigned long root = of_get_flat_dt_root();
+
 	/* initialize the io descriptors we need for initialization */
-	if (of_machine_is_compatible("samsung,exynos5440"))
-		iotable_init(exynos5440_iodesc, ARRAY_SIZE(exynos5440_iodesc));
-	else
-		iotable_init(exynos_iodesc, ARRAY_SIZE(exynos_iodesc));
+	if (of_flat_dt_is_compatible(root, "samsung,exynos5440")) {
+		iodesc = exynos5440_iodesc;
+		iodesc_sz = ARRAY_SIZE(exynos5440_iodesc);
+	}
+#endif
+
+	iotable_init(iodesc, iodesc_sz);
 
 	if (mach_desc)
 		iotable_init(mach_desc, size);

arch/arm/mach-exynos/mach-exynos5-dt.c

@@ -10,6 +10,7 @@
 */
 
 #include <linux/of_platform.h>
+#include <linux/of_fdt.h>
 #include <linux/serial_core.h>
 
 #include <asm/mach/arch.h>
@@ -83,9 +84,11 @@ static const struct of_dev_auxdata exynos5440_auxdata_lookup[] __initconst = {
 
 static void __init exynos5_dt_map_io(void)
 {
+	unsigned long root = of_get_flat_dt_root();
+
 	exynos_init_io(NULL, 0);
 
-	if (of_machine_is_compatible("samsung,exynos5250"))
+	if (of_flat_dt_is_compatible(root, "samsung,exynos5250"))
 		s3c24xx_init_clocks(24000000);
 }