clocksource: add common of_clksrc_init() function

It is desirable to move all clocksource drivers to drivers/clocksource,
yet each requires its own initialization function. We'd rather not
pollute <linux/> with a header for each function. Instead, create a
single of_clksrc_init() function which will determine which clocksource
driver to initialize based on device tree.

Based on a similar patch for drivers/irqchip by Thomas Petazzoni.

Signed-off-by: Stephen Warren <swarren@nvidia.com>

2 files changed, 18 insertions, 0 deletions

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index d1ea7ce0b4cb..1e744c5a0ffe 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -149,6 +149,14 @@
 #define TRACE_SYSCALLS()
 #endif
 
+#ifdef CONFIG_CLKSRC_OF
+#define CLKSRC_OF_TABLES() . = ALIGN(8);                                \
+                           VMLINUX_SYMBOL(__clksrc_of_table) = .;       \
+                           *(__clksrc_of_table)                         \
+                           *(__clksrc_of_table_end)
+#else
+#define CLKSRC_OF_TABLES()
+#endif
 
 #define KERNEL_DTB()                                                    \
         STRUCT_ALIGN();                                                 \
@@ -493,6 +501,7 @@
         DEV_DISCARD(init.rodata)                                        \
         CPU_DISCARD(init.rodata)                                        \
         MEM_DISCARD(init.rodata)                                        \
+        CLKSRC_OF_TABLES()                                              \
         KERNEL_DTB()
 
 #define INIT_TEXT                                                       \
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 4dceaf8ae152..7944f14ea947 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -332,4 +332,13 @@ extern int clocksource_mmio_init(void __iomem *, const char *,
 
 extern int clocksource_i8253_init(void);
 
+#ifdef CONFIG_CLKSRC_OF
+extern void clocksource_of_init(void);
+
+#define CLOCKSOURCE_OF_DECLARE(name, compat, fn)                        \
+        static const struct of_device_id __clksrc_of_table_##name       \
+                __used __section(__clksrc_of_table)                     \
+                 = { .compatible = compat, .data = fn };
+#endif
+
 #endif /* _LINUX_CLOCKSOURCE_H */