[Qemu-devel] [PATCH 7/7] target-alpha: Add high-resolution access to wall clock and an alarm.

[Richard Henderson <rth@twiddle.net>]

The alarm is a fully general one-shot time comparator, which will be
usable under Linux as a hrtimer source.  It's much more flexible than
the RTC source available on real hardware.

The wall clock allows the guest access to the host timekeeping.  Much
like the KVM wall clock source for other guests.

Both are accessed via the PALcode Cserve entry point.

Signed-off-by: Richard Henderson <rth@twiddle.net>
---
 hw/alpha_typhoon.c       |   22 ++++++++++++++++++++--
 target-alpha/cpu.h       |    4 ++++
 target-alpha/helper.h    |    4 ++++
 target-alpha/op_helper.c |   15 +++++++++++++++
 target-alpha/translate.c |   14 ++++++++++++++
 5 files changed, 57 insertions(+), 2 deletions(-)

diff --git a/hw/alpha_typhoon.c b/hw/alpha_typhoon.c
index 7cdf7d3..731b6ea 100644
--- a/hw/alpha_typhoon.c
+++ b/hw/alpha_typhoon.c
@@ -681,6 +681,16 @@ static void typhoon_set_timer_irq(void *opaque, int irq, int level)
     }
 }
 
+static void typhoon_alarm_timer(void *opaque)
+{
+    TyphoonState *s = (TyphoonState *)((uintptr_t)opaque & ~3);
+    int cpu = (uintptr_t)opaque & 3;
+
+    /* Set the ITI bit for this cpu.  */
+    s->cchip.misc |= 1 << (cpu + 4);
+    cpu_interrupt(s->cchip.cpu[cpu], CPU_INTERRUPT_TIMER);
+}
+
 PCIBus *typhoon_init(qemu_irq *p_isa_irq, qemu_irq *p_rtc_irq,
                      CPUState *cpus[3], pci_map_irq_fn sys_map_irq)
 {
@@ -689,14 +699,22 @@ PCIBus *typhoon_init(qemu_irq *p_isa_irq, qemu_irq *p_rtc_irq,
     PCIHostState *p;
     TyphoonState *s;
     PCIBus *b;
-    int region;
+    int i, region;
 
     dev = qdev_create(NULL, "typhoon-pcihost");
     p = FROM_SYSBUS(PCIHostState, sysbus_from_qdev(dev));
     s = container_of(p, TyphoonState, host);
 
     /* Remember the CPUs so that we can deliver interrupts to them.  */
-    memcpy(s->cchip.cpu, cpus, 4 * sizeof(CPUState *));
+    for (i = 0; i < 4; i++) {
+        CPUState *env = cpus[i];
+        s->cchip.cpu[i] = env;
+        if (env) {
+            env->alarm_timer = qemu_new_timer_ns(rtc_clock,
+                                                 typhoon_alarm_timer,
+                                                 (void *)((uintptr_t)s + i));
+        }
+    }
 
     *p_isa_irq = *qemu_allocate_irqs(typhoon_set_isa_irq, s, 1);
     *p_rtc_irq = *qemu_allocate_irqs(typhoon_set_timer_irq, s, 1);
diff --git a/target-alpha/cpu.h b/target-alpha/cpu.h
index 919be12..d0b569b 100644
--- a/target-alpha/cpu.h
+++ b/target-alpha/cpu.h
@@ -265,6 +265,10 @@ struct CPUAlphaState {
     uint64_t scratch[24];
 #endif
 
+    /* This alarm doesn't exist in real hardware; we wish it did.  */
+    struct QEMUTimer *alarm_timer;
+    uint64_t alarm_expire;
+
 #if TARGET_LONG_BITS > HOST_LONG_BITS
     /* temporary fixed-point registers
      * used to emulate 64 bits target on 32 bits hosts
diff --git a/target-alpha/helper.h b/target-alpha/helper.h
index c352c24..b693cee 100644
--- a/target-alpha/helper.h
+++ b/target-alpha/helper.h
@@ -113,7 +113,11 @@ DEF_HELPER_2(stq_c_phys, i64, i64, i64)
 
 DEF_HELPER_FLAGS_0(tbia, TCG_CALL_CONST, void)
 DEF_HELPER_FLAGS_1(tbis, TCG_CALL_CONST, void, i64)
+
 DEF_HELPER_1(halt, void, i64);
+
+DEF_HELPER_FLAGS_0(get_time, TCG_CALL_CONST, i64)
+DEF_HELPER_FLAGS_1(set_alarm, TCG_CALL_CONST, void, i64)
 #endif
 
 #include "def-helper.h"
diff --git a/target-alpha/op_helper.c b/target-alpha/op_helper.c
index ad85e4c..623f1c3 100644
--- a/target-alpha/op_helper.c
+++ b/target-alpha/op_helper.c
@@ -1225,6 +1225,21 @@ void helper_halt(uint64_t restart)
         qemu_system_shutdown_request();
     }
 }
+
+uint64_t helper_get_time(void)
+{
+    return qemu_get_clock_ns(rtc_clock);
+}
+
+void helper_set_alarm(uint64_t expire)
+{
+    if (expire) {
+        env->alarm_expire = expire;
+        qemu_mod_timer(env->alarm_timer, expire);
+    } else {
+        qemu_del_timer(env->alarm_timer);
+    }
+}
 #endif
 
 /*****************************************************************************/
diff --git a/target-alpha/translate.c b/target-alpha/translate.c
index b1609e3..f386d21 100644
--- a/target-alpha/translate.c
+++ b/target-alpha/translate.c
@@ -1590,6 +1590,9 @@ static int cpu_pr_data(int pr)
         return offsetof(CPUAlphaState, shadow[pr - 32]);
     case 40 ... 63:
         return offsetof(CPUAlphaState, scratch[pr - 40]);
+
+    case 251:
+        return offsetof(CPUAlphaState, alarm_expire);
     }
     return 0;
 }
@@ -1604,6 +1607,12 @@ static void gen_mfpr(int ra, int regno)
         return;
     }
 
+    if (regno == 250) {
+        /* WALL_TIME */
+        gen_helper_get_time(cpu_ir[ra]);
+        return;
+    }
+
     /* The basic registers are data only, and unknown registers
        are read-zero, write-ignore.  */
     if (data == 0) {
@@ -1650,6 +1659,11 @@ static ExitStatus gen_mtpr(DisasContext *ctx, int rb, int regno)
         gen_helper_halt(tmp);
         return EXIT_PC_STALE;
 
+    case 251:
+        /* ALARM */
+        gen_helper_set_alarm(tmp);
+        break;
+
     default:
         /* The basic registers are data only, and unknown registers
            are read-zero, write-ignore.  */
-- 
1.7.4.4