[PATCH 2/2] hw: timer: ibex_timer: update/add reg address

[Alistair Francis <alistair.francis@opensource.wdc.com>]

From: Wilfred Mallawa <wilfred.mallawa@wdc.com>

The following changes:
1. Fixes the incorrectly set CTRL register address. As
per [1] https://docs.opentitan.org/hw/ip/rv_timer/doc/#register-table

The CTRL register is @ 0x04.

This was found when attempting to fixup a bug where a timer_interrupt
was not serviced on TockOS-OpenTitan.

2. Adds ALERT_TEST register as documented on [1], adding repective
   switch cases to error handle and later implement functionality.

Signed-off-by: Wilfred Mallawa <wilfred.mallawa@wdc.com>
---
 hw/timer/ibex_timer.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/hw/timer/ibex_timer.c b/hw/timer/ibex_timer.c
index 66e1f8e48c..096588ac8a 100644
--- a/hw/timer/ibex_timer.c
+++ b/hw/timer/ibex_timer.c
@@ -34,7 +34,9 @@
 #include "target/riscv/cpu.h"
 #include "migration/vmstate.h"
 
-REG32(CTRL, 0x00)
+REG32(ALERT_TEST, 0x00)
+    FIELD(ALERT_TEST, FATAL_FAULT, 0, 1)
+REG32(CTRL, 0x04)
     FIELD(CTRL, ACTIVE, 0, 1)
 REG32(CFG0, 0x100)
     FIELD(CFG0, PRESCALE, 0, 12)
@@ -143,6 +145,10 @@ static uint64_t ibex_timer_read(void *opaque, hwaddr addr,
     uint64_t retvalue = 0;
 
     switch (addr >> 2) {
+    case R_ALERT_TEST:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                        "Attempted to read ALERT_TEST, a write only register");
+        break;
     case R_CTRL:
         retvalue = s->timer_ctrl;
         break;
@@ -186,6 +192,9 @@ static void ibex_timer_write(void *opaque, hwaddr addr,
     uint32_t val = val64;
 
     switch (addr >> 2) {
+    case R_ALERT_TEST:
+        qemu_log_mask(LOG_UNIMP, "Alert triggering not supported");
+        break;
     case R_CTRL:
         s->timer_ctrl = val;
         break;
-- 
2.34.1