clocksource: fixup ux500 build problems

Based on a patch from Arnd Bergmann this fixes up the build
problem of assigning a non-existing global when the ux500 PRCMU
timer is not linked in by passing its base address to the init
function. We also add a missing <linux/errno.h> inclusion and
staticize the dummy function.

Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

arch/arm/mach-ux500/timer.c

@@ -5,6 +5,7 @@
  * Author: Mattias Wallin <mattias.wallin@stericsson.com> for ST-Ericsson
  */
 #include <linux/io.h>
+#include <linux/errno.h>
 #include <linux/clksrc-dbx500-prcmu.h>
 
 #include <asm/localtimer.h>
@@ -16,18 +17,20 @@
 
 static void __init ux500_timer_init(void)
 {
+	void __iomem *prcmu_timer_base;
+
 	if (cpu_is_u5500()) {
 #ifdef CONFIG_LOCAL_TIMERS
 		twd_base = __io_address(U5500_TWD_BASE);
 #endif
 		mtu_base = __io_address(U5500_MTU0_BASE);
-		clksrc_dbx500_timer_base = __io_address(U5500_PRCMU_TIMER_3_BASE);
+		prcmu_timer_base = __io_address(U5500_PRCMU_TIMER_3_BASE);
 	} else if (cpu_is_u8500()) {
 #ifdef CONFIG_LOCAL_TIMERS
 		twd_base = __io_address(U8500_TWD_BASE);
 #endif
 		mtu_base = __io_address(U8500_MTU0_BASE);
-		clksrc_dbx500_timer_base = __io_address(U8500_PRCMU_TIMER_4_BASE);
+		prcmu_timer_base = __io_address(U8500_PRCMU_TIMER_4_BASE);
 	} else {
 		ux500_unknown_soc();
 	}
@@ -50,7 +53,7 @@ static void __init ux500_timer_init(void)
 	 */
 
 	nmdk_timer_init();
-	clksrc_dbx500_prcmu_init();
+	clksrc_dbx500_prcmu_init(prcmu_timer_base);
 }
 
 static void ux500_timer_reset(void)

drivers/clocksource/clksrc-dbx500-prcmu.c

@@ -31,7 +31,7 @@
 
 #define SCHED_CLOCK_MIN_WRAP 131072 /* 2^32 / 32768 */
 
-void __iomem *clksrc_dbx500_timer_base;
+static void __iomem *clksrc_dbx500_timer_base;
 
 static cycle_t clksrc_dbx500_prcmu_read(struct clocksource *cs)
 {
@@ -79,8 +79,10 @@ static void notrace clksrc_dbx500_prcmu_update_sched_clock(void)
 }
 #endif
 
-void __init clksrc_dbx500_prcmu_init(void)
+void __init clksrc_dbx500_prcmu_init(void __iomem *base)
 {
+	clksrc_dbx500_timer_base = base;
+
 	/*
 	 * The A9 sub system expects the timer to be configured as
 	 * a continous looping timer.

include/linux/clksrc-dbx500-prcmu.h

@@ -11,12 +11,10 @@
 #include <linux/init.h>
 #include <linux/io.h>
 
-extern void __iomem *clksrc_dbx500_timer_base;
-
 #ifdef CONFIG_CLKSRC_DBX500_PRCMU
-void __init clksrc_dbx500_prcmu_init(void);
+void __init clksrc_dbx500_prcmu_init(void __iomem *base);
 #else
-void __init clksrc_dbx500_prcmu_init(void) {}
+static inline void __init clksrc_dbx500_prcmu_init(void __iomem *base) {}
 #endif
 
 #endif