i8254: Factor out pit_get_channel_info

Instead of providing 4 individual query functions for mode, gate, output
and initial counter state, introduce a service that queries all
information at once. This comes with tiny additional costs for
pcspk_callback but with a much cleaner interface. Also, it will simplify
the implementation of the KVM in-kernel PIT model.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

hw/i8254.c

@@ -90,7 +90,7 @@ static int pit_get_count(PITChannelState *s)
 }
 
 /* get pit output bit */
-static int pit_get_out1(PITChannelState *s, int64_t current_time)
+static int pit_get_out(PITChannelState *s, int64_t current_time)
 {
     uint64_t d;
     int out;
@@ -122,13 +122,6 @@ static int pit_get_out1(PITChannelState *s, int64_t current_time)
     return out;
 }
 
-int pit_get_out(ISADevice *dev, int channel, int64_t current_time)
-{
-    PITState *pit = DO_UPCAST(PITState, dev, dev);
-    PITChannelState *s = &pit->channels[channel];
-    return pit_get_out1(s, current_time);
-}
-
 /* return -1 if no transition will occur.  */
 static int64_t pit_get_next_transition_time(PITChannelState *s,
                                             int64_t current_time)
@@ -215,25 +208,15 @@ void pit_set_gate(ISADevice *dev, int channel, int val)
     s->gate = val;
 }
 
-int pit_get_gate(ISADevice *dev, int channel)
+void pit_get_channel_info(ISADevice *dev, int channel, PITChannelInfo *info)
 {
     PITState *pit = DO_UPCAST(PITState, dev, dev);
     PITChannelState *s = &pit->channels[channel];
-    return s->gate;
-}
 
-int pit_get_initial_count(ISADevice *dev, int channel)
+    info->gate = s->gate;
-{
+    info->mode = s->mode;
-    PITState *pit = DO_UPCAST(PITState, dev, dev);
+    info->initial_count = s->count;
-    PITChannelState *s = &pit->channels[channel];
+    info->out = pit_get_out(s, qemu_get_clock_ns(vm_clock));
-    return s->count;
-}
-
-int pit_get_mode(ISADevice *dev, int channel)
-{
-    PITState *pit = DO_UPCAST(PITState, dev, dev);
-    PITChannelState *s = &pit->channels[channel];
-    return s->mode;
 }
 
 static inline void pit_load_count(PITChannelState *s, int val)
@@ -274,7 +257,9 @@ static void pit_ioport_write(void *opaque, uint32_t addr, uint32_t val)
                     if (!(val & 0x10) && !s->status_latched) {
                         /* status latch */
                         /* XXX: add BCD and null count */
-                        s->status =  (pit_get_out1(s, qemu_get_clock_ns(vm_clock)) << 7) |
+                        s->status =
+                            (pit_get_out(s,
+                                         qemu_get_clock_ns(vm_clock)) << 7) |
                             (s->rw_mode << 4) |
                             (s->mode << 1) |
                             s->bcd;
@@ -381,7 +366,7 @@ static void pit_irq_timer_update(PITChannelState *s, int64_t current_time)
         return;
     }
     expire_time = pit_get_next_transition_time(s, current_time);
-    irq_level = pit_get_out1(s, current_time);
+    irq_level = pit_get_out(s, current_time);
     qemu_set_irq(s->irq, irq_level);
 #ifdef DEBUG_PIT
     printf("irq_level=%d next_delay=%f\n",

hw/i8254.h

@@ -30,6 +30,13 @@
 
 #define PIT_FREQ 1193182
 
+typedef struct PITChannelInfo {
+    int gate;
+    int mode;
+    int initial_count;
+    int out;
+} PITChannelInfo;
+
 static inline ISADevice *pit_init(ISABus *bus, int base, int isa_irq,
                                   qemu_irq alt_irq)
 {
@@ -45,9 +52,6 @@ static inline ISADevice *pit_init(ISABus *bus, int base, int isa_irq,
 }
 
 void pit_set_gate(ISADevice *dev, int channel, int val);
-int pit_get_gate(ISADevice *dev, int channel);
+void pit_get_channel_info(ISADevice *dev, int channel, PITChannelInfo *info);
-int pit_get_initial_count(ISADevice *dev, int channel);
-int pit_get_mode(ISADevice *dev, int channel);
-int pit_get_out(ISADevice *dev, int channel, int64_t current_time);
 
 #endif /* !HW_I8254_H */

hw/pcspk.c

@@ -75,12 +75,16 @@ static inline void generate_samples(PCSpkState *s)
 static void pcspk_callback(void *opaque, int free)
 {
     PCSpkState *s = opaque;
+    PITChannelInfo ch;
     unsigned int n;
 
-    if (pit_get_mode(s->pit, 2) != 3)
+    pit_get_channel_info(s->pit, 2, &ch);
-        return;
 
-    n = pit_get_initial_count(s->pit, 2);
+    if (ch.mode != 3) {
+        return;
+    }
+
+    n = ch.initial_count;
     /* avoid frequencies that are not reproducible with sample rate */
     if (n < PCSPK_MIN_COUNT)
         n = 0;
@@ -121,12 +125,14 @@ static uint64_t pcspk_io_read(void *opaque, target_phys_addr_t addr,
                               unsigned size)
 {
     PCSpkState *s = opaque;
-    int out;
+    PITChannelInfo ch;
+
+    pit_get_channel_info(s->pit, 2, &ch);
 
     s->dummy_refresh_clock ^= (1 << 4);
-    out = pit_get_out(s->pit, 2, qemu_get_clock_ns(vm_clock)) << 5;
 
-    return pit_get_gate(s->pit, 2) | (s->data_on << 1) | s->dummy_refresh_clock | out;
+    return ch.gate | (s->data_on << 1) | s->dummy_refresh_clock |
+       (ch.out << 5);
 }
 
 static void pcspk_io_write(void *opaque, target_phys_addr_t addr, uint64_t val,