ARM: mach-shmobile: Introduce shmobile_setup_delay()

Add the function shmobile_setup_delay() to let platforms
configure their maximum loops per jiffy delay. With this
jiffies calculation done the dependency on early timer
is removed.

In the future this allows us to assign timers
using the regular driver model via the device tree.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

2 files changed, 19 insertions, 0 deletions

diff --git a/arch/arm/mach-shmobile/include/mach/common.h b/arch/arm/mach-shmobile/include/mach/common.h
index 83ad3fe0a75f..cc1d73514ffa 100644
--- a/arch/arm/mach-shmobile/include/mach/common.h
+++ b/arch/arm/mach-shmobile/include/mach/common.h
@@ -3,6 +3,8 @@
 
 extern void shmobile_earlytimer_init(void);
 extern struct sys_timer shmobile_timer;
+extern void shmobile_setup_delay(unsigned int max_cpu_core_mhz,
+                                 unsigned int mult, unsigned int div);
 struct twd_local_timer;
 void shmobile_twd_init(struct twd_local_timer *twd_local_timer);
 extern void shmobile_setup_console(void);
diff --git a/arch/arm/mach-shmobile/timer.c b/arch/arm/mach-shmobile/timer.c
index 2fba5f3d1c8a..599e0081a533 100644
--- a/arch/arm/mach-shmobile/timer.c
+++ b/arch/arm/mach-shmobile/timer.c
@@ -19,9 +19,26 @@
  *
  */
 #include <linux/platform_device.h>
+#include <linux/delay.h>
 #include <asm/mach/time.h>
 #include <asm/smp_twd.h>
 
+void __init shmobile_setup_delay(unsigned int max_cpu_core_mhz,
+                                 unsigned int mult, unsigned int div)
+{
+        /* calculate a worst-case loops-per-jiffy value
+         * based on maximum cpu core mhz setting and the
+         * __delay() implementation in arch/arm/lib/delay.S
+         *
+         * this will result in a longer delay than expected
+         * when the cpu core runs on lower frequencies.
+         */
+
+        unsigned int value = (1000000 * mult) / (HZ * div);
+
+        lpj_fine = max_cpu_core_mhz * value;
+}
+
 static void __init shmobile_late_time_init(void)
 {
         /*