From: Jean-Christophe DUBOIS <jcd@tribudubois.net>
Previous patch changed based on Christian Krafft's comment.

On some legacy SLOF tree the generic code is unable to ioremap some Cell BE
registers. Therefore the "generic" functions are returning a NULL pointer,
triggering a crash on such platforms.

Let's handle this more gracefully.

Signed-off-by: Jean-Christophe DUBOIS <jcd@tribudubois.net>
Acked-by: Christian Kraff <krafft@de.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>

Index: linux-2.6/arch/powerpc/platforms/cell/cbe_cpufreq.c
===================================================================
--- linux-2.6.orig/arch/powerpc/platforms/cell/cbe_cpufreq.c
+++ linux-2.6/arch/powerpc/platforms/cell/cbe_cpufreq.c
@@ -24,6 +24,7 @@
 #include <asm/machdep.h>
 #include <asm/of_platform.h>
 #include <asm/prom.h>
+#include "cbe_regs.h"
 #include "cbe_cpufreq.h"
 
 static DEFINE_MUTEX(cbe_switch_mutex);
@@ -78,6 +79,15 @@ static int cbe_cpufreq_cpu_init(struct c
 
 	pr_debug("init cpufreq on CPU %d\n", policy->cpu);
 
+	/*
+	 * Let's check we can actually get to the CELL regs
+	 */
+	if (!cbe_get_cpu_pmd_regs(policy->cpu) ||
+	    !cbe_get_cpu_mic_tm_regs(policy->cpu)) {
+		pr_info("invalid CBE regs pointers for cpufreq\n");
+		return -EINVAL;
+	}
+
 	max_freqp = of_get_property(cpu, "clock-frequency", NULL);
 
 	of_node_put(cpu);

--