[Qemu-devel] [RFC PATCH 03/15] aspeed/timer: Add support for control register 3

["Cédric Le Goater" <clg@kaod.org>]

The AST2500 timer has a third control register that is used to
implement a set-to-clear feature for the main control register.

This models the behaviour expected by the AST2500 while maintaining
the same behaviour for the AST2400.

Based on previous work from Joel Stanley.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
 include/hw/timer/aspeed_timer.h |  1 +
 hw/timer/aspeed_timer.c         | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/include/hw/timer/aspeed_timer.h b/include/hw/timer/aspeed_timer.h
index a791fee276f4..1e0288ebc49f 100644
--- a/include/hw/timer/aspeed_timer.h
+++ b/include/hw/timer/aspeed_timer.h
@@ -58,6 +58,7 @@ typedef struct AspeedTimerCtrlState {
 
     uint32_t ctrl;
     uint32_t ctrl2;
+    uint32_t ctrl3;
     AspeedTimer timers[ASPEED_TIMER_NR_TIMERS];
 
     AspeedSCUState *scu;
diff --git a/hw/timer/aspeed_timer.c b/hw/timer/aspeed_timer.c
index c78bc1bd2d25..d70e78a0293e 100644
--- a/hw/timer/aspeed_timer.c
+++ b/hw/timer/aspeed_timer.c
@@ -498,6 +498,8 @@ static uint64_t aspeed_2500_timer_read(AspeedTimerCtrlState *s, hwaddr offset)
 
     switch (offset) {
     case 0x38:
+        value = s->ctrl3 & BIT(0);
+        break;
     case 0x3C:
     default:
         qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset 0x%" HWADDR_PRIx "\n",
@@ -511,9 +513,24 @@ static uint64_t aspeed_2500_timer_read(AspeedTimerCtrlState *s, hwaddr offset)
 static void aspeed_2500_timer_write(AspeedTimerCtrlState *s, hwaddr offset,
                                     uint64_t value)
 {
+    const uint32_t tv = (uint32_t)(value & 0xFFFFFFFF);
+    uint8_t command;
+
     switch (offset) {
     case 0x38:
+        command = (value >> 1) & 0xFF;
+        if (command == 0xAE) {
+            s->ctrl3 = 0x1;
+        } else if (command == 0xEA) {
+            s->ctrl3 = 0x0;
+        }
+        break;
     case 0x3C:
+        if (s->ctrl3 & BIT(0)) {
+            aspeed_timer_set_ctrl(s, s->ctrl & ~tv);
+        }
+        break;
+
     default:
         qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset 0x%" HWADDR_PRIx "\n",
                 __func__, offset);
@@ -574,6 +591,7 @@ static void aspeed_timer_reset(DeviceState *dev)
     }
     s->ctrl = 0;
     s->ctrl2 = 0;
+    s->ctrl3 = 0;
 }
 
 static const VMStateDescription vmstate_aspeed_timer = {
@@ -597,6 +615,7 @@ static const VMStateDescription vmstate_aspeed_timer_state = {
     .fields = (VMStateField[]) {
         VMSTATE_UINT32(ctrl, AspeedTimerCtrlState),
         VMSTATE_UINT32(ctrl2, AspeedTimerCtrlState),
+        VMSTATE_UINT32(ctrl3, AspeedTimerCtrlState),
         VMSTATE_STRUCT_ARRAY(timers, AspeedTimerCtrlState,
                              ASPEED_TIMER_NR_TIMERS, 1, vmstate_aspeed_timer,
                              AspeedTimer),
-- 
2.21.0