[v3,06/11] hw/openrisc: Initialize timer time at startup

Commit Message

Stafford Horne July 29, 2022, 11:01 p.m. UTC

The last_clk time was initialized at zero, this means when we calculate
the first delta we will calculate 0 vs current time which could cause
unnecessary hops.

This patch moves timer initialization to the cpu reset.  There are two
resets registered here:

 1. Per cpu timer mask (ttmr) reset.
 2. Global cpu timer (last_clk and ttcr) reset, attached to the first
    cpu only.

Signed-off-by: Stafford Horne <[e-mail]>
---
Since v2:
 - Moved timer init from init to reset suggested by Richard

 hw/openrisc/cputimer.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

Comments

Richard Henderson July 29, 2022, 11:42 p.m. UTC | #1

On 7/29/22 16:01, Stafford Horne wrote:
> The last_clk time was initialized at zero, this means when we calculate
> the first delta we will calculate 0 vs current time which could cause
> unnecessary hops.
> 
> This patch moves timer initialization to the cpu reset.  There are two
> resets registered here:
> 
>   1. Per cpu timer mask (ttmr) reset.
>   2. Global cpu timer (last_clk and ttcr) reset, attached to the first
>      cpu only.
> 
> Signed-off-by: Stafford Horne<[e-mail]>
> ---
> Since v2:
>   - Moved timer init from init to reset suggested by Richard
> 
>   hw/openrisc/cputimer.c | 22 +++++++++++++++++++++-
>   1 file changed, 21 insertions(+), 1 deletion(-)

Reviewed-by: Richard Henderson <[e-mail]>

r~

Patch

diff --git a/hw/openrisc/cputimer.c b/hw/openrisc/cputimer.c
index 93268815d8..10163b391b 100644
--- a/hw/openrisc/cputimer.c
+++ b/hw/openrisc/cputimer.c
@@ -22,6 +22,7 @@ 
 #include "cpu.h"
 #include "migration/vmstate.h"
 #include "qemu/timer.h"
+#include "sysemu/reset.h"
 
 #define TIMER_PERIOD 50 /* 50 ns period for 20 MHz timer */
 
@@ -122,6 +123,24 @@  static void openrisc_timer_cb(void *opaque)
     qemu_cpu_kick(CPU(cpu));
 }
 
+/* Reset the per CPU counter state. */
+static void openrisc_count_reset(void *opaque)
+{
+    OpenRISCCPU *cpu = opaque;
+
+    if (cpu->env.is_counting) {
+        cpu_openrisc_count_stop(cpu);
+    }
+    cpu->env.ttmr = 0x00000000;
+}
+
+/* Reset the global timer state. */
+static void openrisc_timer_reset(void *opaque)
+{
+    or1k_timer->ttcr = 0x00000000;
+    or1k_timer->last_clk = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+}
+
 static const VMStateDescription vmstate_or1k_timer = {
     .name = "or1k_timer",
     .version_id = 1,
@@ -136,10 +155,11 @@  static const VMStateDescription vmstate_or1k_timer = {
 void cpu_openrisc_clock_init(OpenRISCCPU *cpu)
 {
     cpu->env.timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, &openrisc_timer_cb, cpu);
-    cpu->env.ttmr = 0x00000000;
 
+    qemu_register_reset(openrisc_count_reset, cpu);
     if (or1k_timer == NULL) {
         or1k_timer = g_new0(OR1KTimerState, 1);
+        qemu_register_reset(openrisc_timer_reset, cpu);
         vmstate_register(NULL, 0, &vmstate_or1k_timer, or1k_timer);
     }
 }