x86/hpet: Use common init for legacy clockevent

[linux-2.6-microblaze.git] / arch / x86 / kernel / hpet.c

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index 80497fe..35633e5 100644 (file)
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -66,6 +66,9 @@ bool                                  boot_hpet_disable;
 bool                                   hpet_force_user;
 static bool                            hpet_verbose;
 
+/*
+ * The HPET clock event device wrapped in a channel for conversion
+ */
 static struct hpet_channel             hpet_channel0;
 
 static inline
@@ -294,22 +297,6 @@ static void hpet_enable_legacy_int(void)
        hpet_legacy_int_enabled = true;
 }
 
-static void hpet_legacy_clockevent_register(struct hpet_channel *hc)
-{
-       /* Start HPET legacy interrupts */
-       hpet_enable_legacy_int();
-
-       /*
-        * Start HPET with the boot CPU's cpumask and make it global after
-        * the IO_APIC has been initialized.
-        */
-       hc->evt.cpumask = cpumask_of(boot_cpu_data.cpu_index);
-       clockevents_config_and_register(&hc->evt, hpet_freq,
-                                       HPET_MIN_PROG_DELTA, 0x7FFFFFFF);
-       global_clock_event = &hc->evt;
-       pr_debug("Clockevent registered\n");
-}
-
 static int hpet_clkevt_set_state_periodic(struct clock_event_device *evt)
 {
        unsigned int channel = clockevent_to_channel(evt)->num;
@@ -430,23 +417,57 @@ static void hpet_init_clockevent(struct hpet_channel *hc, unsigned int rating)
        }
 }
 
-/*
- * The HPET clock event device wrapped in a channel for conversion
- */
-static struct hpet_channel hpet_channel0 = {
-       .evt = {
-               .name                   = "hpet",
-               .features               = CLOCK_EVT_FEAT_PERIODIC |
-                                         CLOCK_EVT_FEAT_ONESHOT,
-               .set_state_periodic     = hpet_clkevt_set_state_periodic,
-               .set_state_oneshot      = hpet_clkevt_set_state_oneshot,
-               .set_state_shutdown     = hpet_clkevt_set_state_shutdown,
-               .tick_resume            = hpet_clkevt_legacy_resume,
-               .set_next_event         = hpet_clkevt_set_next_event,
-               .irq                    = 0,
-               .rating                 = 50,
-       }
-};
+static void __init hpet_legacy_clockevent_register(struct hpet_channel *hc)
+{
+       /*
+        * Start HPET with the boot CPU's cpumask and make it global after
+        * the IO_APIC has been initialized.
+        */
+       hc->cpu = boot_cpu_data.cpu_index;
+       strncpy(hc->name, "hpet", sizeof(hc->name));
+       hpet_init_clockevent(hc, 50);
+
+       hc->evt.tick_resume     = hpet_clkevt_legacy_resume;
+
+       /*
+        * Legacy horrors and sins from the past. HPET used periodic mode
+        * unconditionally forever on the legacy channel 0. Removing the
+        * below hack and using the conditional in hpet_init_clockevent()
+        * makes at least Qemu and one hardware machine fail to boot.
+        * There are two issues which cause the boot failure:
+        *
+        * #1 After the timer delivery test in IOAPIC and the IOAPIC setup
+        *    the next interrupt is not delivered despite the HPET channel
+        *    being programmed correctly. Reprogramming the HPET after
+        *    switching to IOAPIC makes it work again. After fixing this,
+        *    the next issue surfaces:
+        *
+        * #2 Due to the unconditional periodic mode availability the Local
+        *    APIC timer calibration can hijack the global clockevents
+        *    event handler without causing damage. Using oneshot at this
+        *    stage makes if hang because the HPET does not get
+        *    reprogrammed due to the handler hijacking. Duh, stupid me!
+        *
+        * Both issues require major surgery and especially the kick HPET
+        * again after enabling IOAPIC results in really nasty hackery.
+        * This 'assume periodic works' magic has survived since HPET
+        * support got added, so it's questionable whether this should be
+        * fixed. Both Qemu and the failing hardware machine support
+        * periodic mode despite the fact that both don't advertise it in
+        * the configuration register and both need that extra kick after
+        * switching to IOAPIC. Seems to be a feature...
+        */
+       hc->evt.features                |= CLOCK_EVT_FEAT_PERIODIC;
+       hc->evt.set_state_periodic      = hpet_clkevt_set_state_periodic;
+
+       /* Start HPET legacy interrupts */
+       hpet_enable_legacy_int();
+
+       clockevents_config_and_register(&hc->evt, hpet_freq,
+                                       HPET_MIN_PROG_DELTA, 0x7FFFFFFF);
+       global_clock_event = &hc->evt;
+       pr_debug("Clockevent registered\n");
+}
 
 /*
  * HPET MSI Support