ARM: mvebu: add a coherency_available() call

This commit extends the coherency fabric code to provide a
coherency_available()function that the SoC code can call to be told
whether coherency support is available or not. On Armada 370/XP,
coherency support is available as soon as the relevant DT node is
present. On some upcoming SoCs, the DT node needs to be present *and*
the system running with CONFIG_SMP enabled.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483228-25625-3-git-send-email-thomas.petazzoni@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

2 files changed, 23 insertions, 8 deletions

diff --git a/arch/arm/mach-mvebu/coherency.c b/arch/arm/mach-mvebu/coherency.c
index 434cf5f90a80..296cf14f08a4 100644
--- a/arch/arm/mach-mvebu/coherency.c
+++ b/arch/arm/mach-mvebu/coherency.c
@@ -39,6 +39,7 @@ static void __iomem *coherency_cpu_base;
 #define IO_SYNC_BARRIER_CTL_OFFSET                 0x0
 
 enum {
+        COHERENCY_FABRIC_TYPE_NONE,
         COHERENCY_FABRIC_TYPE_ARMADA_370_XP,
 };
 
@@ -144,7 +145,7 @@ static void __init armada_370_coherency_init(struct device_node *np)
         set_cpu_coherent(cpu_logical_map(smp_processor_id()), 0);
 }
 
-int __init coherency_init(void)
+static int coherency_type(void)
 {
         struct device_node *np;
 
@@ -155,27 +156,40 @@ int __init coherency_init(void)
                 int type;
 
                 type = (int) match->data;
-                pr_info("Initializing Coherency fabric\n");
 
+                /* Armada 370/XP coherency works in both UP and SMP */
                 if (type == COHERENCY_FABRIC_TYPE_ARMADA_370_XP)
-                        armada_370_coherency_init(np);
+                        return type;
 
                 of_node_put(np);
         }
 
-        return 0;
+        return COHERENCY_FABRIC_TYPE_NONE;
 }
 
-static int __init coherency_late_init(void)
+int coherency_available(void)
 {
+        return coherency_type() != COHERENCY_FABRIC_TYPE_NONE;
+}
+
+int __init coherency_init(void)
+{
+        int type = coherency_type();
         struct device_node *np;
 
         np = of_find_matching_node(NULL, of_coherency_table);
-        if (np) {
+
+        if (type == COHERENCY_FABRIC_TYPE_ARMADA_370_XP)
+                armada_370_coherency_init(np);
+
+        return 0;
+}
+
+static int __init coherency_late_init(void)
+{
+        if (coherency_available())
                 bus_register_notifier(&platform_bus_type,
                                       &mvebu_hwcc_platform_nb);
-                of_node_put(np);
-        }
         return 0;
 }
 
diff --git a/arch/arm/mach-mvebu/coherency.h b/arch/arm/mach-mvebu/coherency.h
index 760226c41353..02f7ec34ced2 100644
--- a/arch/arm/mach-mvebu/coherency.h
+++ b/arch/arm/mach-mvebu/coherency.h
@@ -18,5 +18,6 @@ extern unsigned long coherency_phys_base;
 
 int set_cpu_coherent(unsigned int cpu_id, int smp_group_id);
 int coherency_init(void);
+int coherency_available(void);
 
 #endif  /* __MACH_370_XP_COHERENCY_H */