linux-kernel - [PATCH] ARM: EXYNOS: Avoid early use of of_machine_is

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Date:	Tue, 27 Nov 2012 11:53:14 -0800
From:	Doug Anderson <dianders@...omium.org>
To:	Olof Johansson <olof@...om.net>
Cc:	Arnd Bergmann <arnd@...db.de>,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org,
	Doug Anderson <dianders@...omium.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Russell King <linux@....linux.org.uk>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] 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: Doug Anderson <dianders@...omium.org>

---
 arch/arm/mach-exynos/common.c          |    5 ++++-
 arch/arm/mach-exynos/mach-exynos5-dt.c |    4 +++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mach-exynos/common.c b/arch/arm/mach-exynos/common.c
index 73b940f..b919f5f 100644
--- a/arch/arm/mach-exynos/common.c
+++ b/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>
@@ -335,8 +336,10 @@ void __init exynos_init_late(void)
 
 void __init exynos_init_io(struct map_desc *mach_desc, int size)
 {
+	unsigned long root = of_get_flat_dt_root();
+
 	/* initialize the io descriptors we need for initialization */
-	if (of_machine_is_compatible("samsung,exynos5440"))
+	if (of_flat_dt_is_compatible(root, "samsung,exynos5440"))
 		iotable_init(exynos5440_iodesc, ARRAY_SIZE(exynos5440_iodesc));
 	else
 		iotable_init(exynos_iodesc, ARRAY_SIZE(exynos_iodesc));
diff --git a/arch/arm/mach-exynos/mach-exynos5-dt.c b/arch/arm/mach-exynos/mach-exynos5-dt.c
index 67fa3c2..7b76c3f 100644
--- a/arch/arm/mach-exynos/mach-exynos5-dt.c
+++ b/arch/arm/mach-exynos/mach-exynos5-dt.c
@@ -122,9 +122,11 @@ 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);
 }
 
-- 
1.7.7.3

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