rtc: use the IRQ callback interface in (old) RTC driver

the previous patch in the old RTC driver.  It also removes the direct
rtc_interrupt() call from arch/x86/kernel/hpetc.c so that there's finally no
(code) dependency to CONFIG_RTC in arch/x86/kernel/hpet.c.

Because of this, it's possible to compile the drivers/char/rtc.ko driver as
module and still use the HPET emulation functionality.  This is also expressed
in Kconfig.

Signed-off-by: Bernhard Walle <bwalle@suse.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Cc: Andi Kleen <ak@suse.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Robert Picco <Robert.Picco@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 14 insertions, 1 deletions

diff --git a/drivers/char/rtc.c b/drivers/char/rtc.c
index 3ac7952fe086..78b151c4d20f 100644
--- a/drivers/char/rtc.c
+++ b/drivers/char/rtc.c
@@ -110,6 +110,8 @@ static int rtc_has_irq = 1;
 #define hpet_set_rtc_irq_bit(arg)               0
 #define hpet_rtc_timer_init()                   do { } while (0)
 #define hpet_rtc_dropped_irq()                  0
+#define hpet_register_irq_handler(h)            0
+#define hpet_unregister_irq_handler(h)          0
 #ifdef RTC_IRQ
 static irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id)
 {
@@ -1027,7 +1029,15 @@ no_irq:
 
 #ifdef RTC_IRQ
         if (is_hpet_enabled()) {
+                int err;
+
                 rtc_int_handler_ptr = hpet_rtc_interrupt;
+                err = hpet_register_irq_handler(rtc_interrupt);
+                if (err != 0) {
+                        printk(KERN_WARNING "hpet_register_irq_handler failed "
+                                        "in rtc_init().");
+                        return err;
+                }
         } else {
                 rtc_int_handler_ptr = rtc_interrupt;
         }
@@ -1050,6 +1060,7 @@ no_irq:
         if (misc_register(&rtc_dev)) {
 #ifdef RTC_IRQ
                 free_irq(RTC_IRQ, NULL);
+                hpet_unregister_irq_handler(rtc_interrupt);
                 rtc_has_irq = 0;
 #endif
                 rtc_release_region();
@@ -1141,8 +1152,10 @@ static void __exit rtc_exit(void)
 #else
         rtc_release_region();
 #ifdef RTC_IRQ
-        if (rtc_has_irq)
+        if (rtc_has_irq) {
                 free_irq(RTC_IRQ, NULL);
+                hpet_unregister_irq_handler(hpet_rtc_interrupt);
+        }
 #endif
 #endif /* CONFIG_SPARC32 */
 }