[Qemu-devel] [PATCH] rewrote timer implementation for rtl8139.

[Frediano Ziglio <freddy77@gmail.com>]

Add a QEMU timer only when needed (timeout status not set, timeout
irq wanted and timer set).

This patch is required for Darwin. Patch has been tested under
FreeBSD, Darwin and Linux.

Signed-off-by: Frediano Ziglio <freddy77@gmail.com>
---
 hw/rtl8139.c |  139 +++++++++++++++++++++++++++++++++++-----------------------
 1 files changed, 84 insertions(+), 55 deletions(-)

diff --git a/hw/rtl8139.c b/hw/rtl8139.c
index f04dd54..72e2242 100644
--- a/hw/rtl8139.c
+++ b/hw/rtl8139.c
@@ -41,6 +41,10 @@
  *                                  segmentation offloading
  *                                  Removed slirp.h dependency
  *                                  Added rx/tx buffer reset when enabling rx/tx operation
+ *
+ *  2010-Feb-04  Frediano Ziglio:   Rewrote timer support using QEMU timer only
+ *                                  when strictly needed (required for for
+ *                                  Darwin)
  */
 
 #include "hw.h"
@@ -60,9 +64,6 @@
 /* Calculate CRCs properly on Rx packets */
 #define RTL8139_CALCULATE_RXCRC 1
 
-/* Uncomment to enable on-board timer interrupts */
-//#define RTL8139_ONBOARD_TIMER 1
-
 #if defined(RTL8139_CALCULATE_RXCRC)
 /* For crc32 */
 #include <zlib.h>
@@ -491,9 +492,12 @@ typedef struct RTL8139State {
 
     /* PCI interrupt timer */
     QEMUTimer *timer;
+    int64_t TimerExpire;
 
 } RTL8139State;
 
+static void rtl8139_set_next_tctr_time(RTL8139State *s, int64_t current_time);
+
 static void prom9346_decode_command(EEprom9346 *eeprom, uint8_t command)
 {
     DEBUG_PRINT(("RTL8139: eeprom command 0x%02x\n", command));
@@ -2522,7 +2526,9 @@ static void rtl8139_IntrMask_write(RTL8139State *s, uint32_t val)
 
     s->IntrMask = val;
 
+    rtl8139_set_next_tctr_time(s, qemu_get_clock(vm_clock));
     rtl8139_update_irq(s);
+
 }
 
 static uint32_t rtl8139_IntrMask_read(RTL8139State *s)
@@ -2555,12 +2561,22 @@ static void rtl8139_IntrStatus_write(RTL8139State *s, uint32_t val)
     rtl8139_update_irq(s);
 
     s->IntrStatus = newStatus;
+    /*
+     * Computing if we miss an interrupt here is not that correct but
+     * considered that we should have had already an interrupt
+     * and probably emulated is slower is better to assume this resetting was
+     * done before testing on previous rtl8139_update_irq lead to IRQ loosing
+     */
+    rtl8139_set_next_tctr_time(s, qemu_get_clock(vm_clock));
     rtl8139_update_irq(s);
+
 #endif
 }
 
 static uint32_t rtl8139_IntrStatus_read(RTL8139State *s)
 {
+    rtl8139_set_next_tctr_time(s, qemu_get_clock(vm_clock));
+
     uint32_t ret = s->IntrStatus;
 
     DEBUG_PRINT(("RTL8139: IntrStatus read(w) val=0x%04x\n", ret));
@@ -2739,6 +2755,46 @@ static void rtl8139_io_writew(void *opaque, uint8_t addr, uint32_t val)
     }
 }
 
+static void rtl8139_set_next_tctr_time(RTL8139State *s, int64_t current_time)
+{
+    int64_t pci_time, next_time;
+    uint32_t low_pci;
+
+    DEBUG_PRINT(("RTL8139: entered rtl8139_set_next_tctr_time\n"));
+
+    if (s->TimerExpire && current_time >= s->TimerExpire) {
+        s->IntrStatus |= PCSTimeout;
+        rtl8139_update_irq(s);
+    }
+
+    /* Set QEMU timer only if needed that is
+     * - TimerInt <> 0 (we have a timer)
+     * - mask = 1 (we want an interrupt timer)
+     * - irq = 0  (irq is not already active)
+     * If any of above change we need to compute timer again
+     * Also we must check if timer is passed without QEMU timer
+     */
+    s->TimerExpire = 0;
+    if (!s->TimerInt) {
+        return;
+    }
+
+    pci_time = muldiv64(current_time - s->TCTR_base, PCI_FREQUENCY,
+                                get_ticks_per_sec());
+    low_pci = pci_time & 0xffffffff;
+    pci_time = pci_time - low_pci + s->TimerInt;
+    if (low_pci >= s->TimerInt) {
+        pci_time += 0x100000000LL;
+    }
+    next_time = s->TCTR_base + muldiv64(pci_time, get_ticks_per_sec(),
+                                                PCI_FREQUENCY);
+    s->TimerExpire = next_time;
+
+    if ((s->IntrMask & PCSTimeout) != 0 && (s->IntrStatus & PCSTimeout) == 0) {
+        qemu_mod_timer(s->timer, next_time);
+    }
+}
+
 static void rtl8139_io_writel(void *opaque, uint8_t addr, uint32_t val)
 {
     RTL8139State *s = opaque;
@@ -2784,13 +2840,16 @@ static void rtl8139_io_writel(void *opaque, uint8_t addr, uint32_t val)
 
         case Timer:
             DEBUG_PRINT(("RTL8139: TCTR Timer reset on write\n"));
-            s->TCTR = 0;
             s->TCTR_base = qemu_get_clock(vm_clock);
+            rtl8139_set_next_tctr_time(s, s->TCTR_base);
             break;
 
         case FlashReg:
             DEBUG_PRINT(("RTL8139: FlashReg TimerInt write val=0x%08x\n", val));
-            s->TimerInt = val;
+            if (s->TimerInt != val) {
+                s->TimerInt = val;
+                rtl8139_set_next_tctr_time(s, qemu_get_clock(vm_clock));
+            }
             break;
 
         default:
@@ -3000,7 +3059,8 @@ static uint32_t rtl8139_io_readl(void *opaque, uint8_t addr)
             break;
 
         case Timer:
-            ret = s->TCTR;
+            ret = muldiv64(qemu_get_clock(vm_clock) - s->TCTR_base,
+                           PCI_FREQUENCY, get_ticks_per_sec());
             DEBUG_PRINT(("RTL8139: TCTR Timer read val=0x%08x\n", ret));
             break;
 
@@ -3105,6 +3165,7 @@ static uint32_t rtl8139_mmio_readl(void *opaque, target_phys_addr_t addr)
 static int rtl8139_post_load(void *opaque, int version_id)
 {
     RTL8139State* s = opaque;
+    rtl8139_set_next_tctr_time(s, qemu_get_clock(vm_clock));
     if (version_id < 4) {
         s->cplus_enabled = s->CpCmd != 0;
     }
@@ -3112,12 +3173,24 @@ static int rtl8139_post_load(void *opaque, int version_id)
     return 0;
 }
 
+static void rtl8139_pre_save(void *opaque)
+{
+    RTL8139State* s = opaque;
+    int64_t current_time = qemu_get_clock(vm_clock);
+
+    /* set IntrStatus correctly */
+    rtl8139_set_next_tctr_time(s, current_time);
+    s->TCTR = muldiv64(current_time - s->TCTR_base, PCI_FREQUENCY,
+                       get_ticks_per_sec());
+}
+
 static const VMStateDescription vmstate_rtl8139 = {
     .name = "rtl8139",
     .version_id = 4,
     .minimum_version_id = 3,
     .minimum_version_id_old = 3,
     .post_load = rtl8139_post_load,
+    .pre_save  = rtl8139_pre_save,
     .fields      = (VMStateField []) {
         VMSTATE_PCI_DEVICE(dev, RTL8139State),
         VMSTATE_PARTIAL_BUFFER(phys, RTL8139State, 6),
@@ -3231,59 +3304,20 @@ static CPUWriteMemoryFunc * const rtl8139_mmio_write[3] = {
     rtl8139_mmio_writel,
 };
 
-static inline int64_t rtl8139_get_next_tctr_time(RTL8139State *s, int64_t current_time)
-{
-    int64_t next_time = current_time +
-        muldiv64(1, get_ticks_per_sec(), PCI_FREQUENCY);
-    if (next_time <= current_time)
-        next_time = current_time + 1;
-    return next_time;
-}
-
-#ifdef RTL8139_ONBOARD_TIMER
 static void rtl8139_timer(void *opaque)
 {
     RTL8139State *s = opaque;
 
-    int is_timeout = 0;
-
-    int64_t  curr_time;
-    uint32_t curr_tick;
-
     if (!s->clock_enabled)
     {
         DEBUG_PRINT(("RTL8139: >>> timer: clock is not running\n"));
         return;
     }
 
-    curr_time = qemu_get_clock(vm_clock);
-
-    curr_tick = muldiv64(curr_time - s->TCTR_base, PCI_FREQUENCY,
-                         get_ticks_per_sec());
-
-    if (s->TimerInt && curr_tick >= s->TimerInt)
-    {
-        if (s->TCTR < s->TimerInt || curr_tick < s->TCTR)
-        {
-            is_timeout = 1;
-        }
-    }
-
-    s->TCTR = curr_tick;
-
-//  DEBUG_PRINT(("RTL8139: >>> timer: tick=%08u\n", s->TCTR));
-
-    if (is_timeout)
-    {
-        DEBUG_PRINT(("RTL8139: >>> timer: timeout tick=%08u\n", s->TCTR));
-        s->IntrStatus |= PCSTimeout;
-        rtl8139_update_irq(s);
-    }
-
-    qemu_mod_timer(s->timer,
-        rtl8139_get_next_tctr_time(s,curr_time));
+    s->IntrStatus |= PCSTimeout;
+    rtl8139_update_irq(s);
+    rtl8139_set_next_tctr_time(s, qemu_get_clock(vm_clock));
 }
-#endif /* RTL8139_ONBOARD_TIMER */
 
 static void rtl8139_cleanup(VLANClientState *nc)
 {
@@ -3301,10 +3335,8 @@ static int pci_rtl8139_uninit(PCIDevice *dev)
         qemu_free(s->cplus_txbuffer);
         s->cplus_txbuffer = NULL;
     }
-#ifdef RTL8139_ONBOARD_TIMER
     qemu_del_timer(s->timer);
     qemu_free_timer(s->timer);
-#endif
     qemu_del_vlan_client(&s->nic->nc);
     return 0;
 }
@@ -3356,12 +3388,9 @@ static int pci_rtl8139_init(PCIDevice *dev)
     s->cplus_txbuffer_len = 0;
     s->cplus_txbuffer_offset = 0;
 
-#ifdef RTL8139_ONBOARD_TIMER
+    s->TimerExpire = 0;
     s->timer = qemu_new_timer(vm_clock, rtl8139_timer, s);
-
-    qemu_mod_timer(s->timer,
-        rtl8139_get_next_tctr_time(s,qemu_get_clock(vm_clock)));
-#endif /* RTL8139_ONBOARD_TIMER */
+    rtl8139_set_next_tctr_time(s, qemu_get_clock(vm_clock));
     return 0;
 }
 
-- 
1.6.3.3