hpet: Make number of timers configurable

One HPET block supports up to 32 timers. Allow to instantiate more than
the recommended and implemented minimum of 3. The number is configured
via the qdev property "timers". It is also saved/restored so that it
need not match between migration peers.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

1 files changed, 40 insertions, 13 deletions

diff --git a/hw/hpet.c b/hw/hpet.c
index f24b227..6187e5e 100644
--- a/hw/hpet.c
+++ b/hw/hpet.c
@@ -60,7 +60,8 @@ typedef struct HPETState {
     uint64_t hpet_offset;
     qemu_irq irqs[HPET_NUM_IRQ_ROUTES];
     uint8_t rtc_irq_level;
-    HPETTimer timer[HPET_NUM_TIMERS];
+    uint8_t num_timers;
+    HPETTimer timer[HPET_MAX_TIMERS];
 
     /* Memory-mapped, software visible registers */
     uint64_t capability;        /* capabilities */
@@ -196,12 +197,25 @@ static void hpet_pre_save(void *opaque)
     s->hpet_counter = hpet_get_ticks(s);
 }
 
+static int hpet_pre_load(void *opaque)
+{
+    HPETState *s = opaque;
+
+    /* version 1 only supports 3, later versions will load the actual value */
+    s->num_timers = HPET_MIN_TIMERS;
+    return 0;
+}
+
 static int hpet_post_load(void *opaque, int version_id)
 {
     HPETState *s = opaque;
 
     /* Recalculate the offset between the main counter and guest time */
     s->hpet_offset = ticks_to_ns(s->hpet_counter) - qemu_get_clock(vm_clock);
+
+    /* Push number of timers into capability returned via HPET_ID */
+    s->capability &= ~HPET_ID_NUM_TIM_MASK;
+    s->capability |= (s->num_timers - 1) << HPET_ID_NUM_TIM_SHIFT;
     return 0;
 }
 
@@ -224,17 +238,19 @@ static const VMStateDescription vmstate_hpet_timer = {
 
 static const VMStateDescription vmstate_hpet = {
     .name = "hpet",
-    .version_id = 1,
+    .version_id = 2,
     .minimum_version_id = 1,
     .minimum_version_id_old = 1,
     .pre_save = hpet_pre_save,
+    .pre_load = hpet_pre_load,
     .post_load = hpet_post_load,
     .fields      = (VMStateField []) {
         VMSTATE_UINT64(config, HPETState),
         VMSTATE_UINT64(isr, HPETState),
         VMSTATE_UINT64(hpet_counter, HPETState),
-        VMSTATE_STRUCT_ARRAY(timer, HPETState, HPET_NUM_TIMERS, 0,
-                             vmstate_hpet_timer, HPETTimer),
+        VMSTATE_UINT8_V(num_timers, HPETState, 2),
+        VMSTATE_STRUCT_VARRAY_UINT8(timer, HPETState, num_timers, 0,
+                                    vmstate_hpet_timer, HPETTimer),
         VMSTATE_END_OF_LIST()
     }
 };
@@ -330,7 +346,7 @@ static uint32_t hpet_ram_readl(void *opaque, target_phys_addr_t addr)
         uint8_t timer_id = (addr - 0x100) / 0x20;
         HPETTimer *timer = &s->timer[timer_id];
 
-        if (timer_id > HPET_NUM_TIMERS - 1) {
+        if (timer_id > s->num_timers) {
             DPRINTF("qemu: timer id out of range\n");
             return 0;
         }
@@ -421,7 +437,7 @@ static void hpet_ram_writel(void *opaque, target_phys_addr_t addr,
         HPETTimer *timer = &s->timer[timer_id];
 
         DPRINTF("qemu: hpet_ram_writel timer_id = %#x \n", timer_id);
-        if (timer_id > HPET_NUM_TIMERS - 1) {
+        if (timer_id > s->num_timers) {
             DPRINTF("qemu: timer id out of range\n");
             return;
         }
@@ -504,7 +520,7 @@ static void hpet_ram_writel(void *opaque, target_phys_addr_t addr,
                 /* Enable main counter and interrupt generation. */
                 s->hpet_offset =
                     ticks_to_ns(s->hpet_counter) - qemu_get_clock(vm_clock);
-                for (i = 0; i < HPET_NUM_TIMERS; i++) {
+                for (i = 0; i < s->num_timers; i++) {
                     if ((&s->timer[i])->cmp != ~0ULL) {
                         hpet_set_timer(&s->timer[i]);
                     }
@@ -512,7 +528,7 @@ static void hpet_ram_writel(void *opaque, target_phys_addr_t addr,
             } else if (deactivating_bit(old_val, new_val, HPET_CFG_ENABLE)) {
                 /* Halt main counter and disable interrupt generation. */
                 s->hpet_counter = hpet_get_ticks(s);
-                for (i = 0; i < HPET_NUM_TIMERS; i++) {
+                for (i = 0; i < s->num_timers; i++) {
                     hpet_del_timer(&s->timer[i]);
                 }
             }
@@ -530,7 +546,7 @@ static void hpet_ram_writel(void *opaque, target_phys_addr_t addr,
             break;
         case HPET_STATUS:
             val = new_val & s->isr;
-            for (i = 0; i < HPET_NUM_TIMERS; i++) {
+            for (i = 0; i < s->num_timers; i++) {
                 if (val & (1 << i)) {
                     update_irq(&s->timer[i], 0);
                 }
@@ -589,7 +605,7 @@ static void hpet_reset(DeviceState *d)
     int i;
     static int count = 0;
 
-    for (i = 0; i < HPET_NUM_TIMERS; i++) {
+    for (i = 0; i < s->num_timers; i++) {
         HPETTimer *timer = &s->timer[i];
 
         hpet_del_timer(timer);
@@ -603,8 +619,9 @@ static void hpet_reset(DeviceState *d)
 
     s->hpet_counter = 0ULL;
     s->hpet_offset = 0ULL;
-    /* 64-bit main counter; 3 timers supported; LegacyReplacementRoute. */
-    s->capability = 0x8086a201ULL;
+    /* 64-bit main counter; LegacyReplacementRoute. */
+    s->capability = 0x8086a001ULL;
+    s->capability |= (s->num_timers - 1) << HPET_ID_NUM_TIM_SHIFT;
     s->capability |= ((HPET_CLK_PERIOD) << 32);
     s->config = 0ULL;
     if (count > 0) {
@@ -637,7 +654,13 @@ static int hpet_init(SysBusDevice *dev)
     for (i = 0; i < HPET_NUM_IRQ_ROUTES; i++) {
         sysbus_init_irq(dev, &s->irqs[i]);
     }
-    for (i = 0; i < HPET_NUM_TIMERS; i++) {
+
+    if (s->num_timers < HPET_MIN_TIMERS) {
+        s->num_timers = HPET_MIN_TIMERS;
+    } else if (s->num_timers > HPET_MAX_TIMERS) {
+        s->num_timers = HPET_MAX_TIMERS;
+    }
+    for (i = 0; i < HPET_MAX_TIMERS; i++) {
         timer = &s->timer[i];
         timer->qemu_timer = qemu_new_timer(vm_clock, hpet_timer, timer);
         timer->tn = i;
@@ -661,6 +684,10 @@ static SysBusDeviceInfo hpet_device_info = {
     .qdev.vmsd    = &vmstate_hpet,
     .qdev.reset   = hpet_reset,
     .init         = hpet_init,
+    .qdev.props = (Property[]) {
+        DEFINE_PROP_UINT8("timers", HPETState, num_timers, HPET_MIN_TIMERS),
+        DEFINE_PROP_END_OF_LIST(),
+    },
 };
 
 static void hpet_register_device(void)