escc: introduce escc_soft_reset_chn() for software reset

This new software reset function is to be called when the appropriate channel
software reset bit is written to register WR9. Its initial implementation is
the same as the existing escc_reset_chn() function used for device reset.

Add a new trace event when the guest initiates a soft reset via the WR9 register
to help diagnose guest reset issues.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20210903113223.19551-4-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>

1 files changed, 38 insertions, 2 deletions

diff --git a/hw/char/escc.c b/hw/char/escc.c
index b0d3b92dc1..697f15f383 100644
--- a/hw/char/escc.c
+++ b/hw/char/escc.c
@@ -297,6 +297,40 @@ static void escc_reset_chn(ESCCChannelState *s)
     clear_queue(s);
 }
 
+static void escc_soft_reset_chn(ESCCChannelState *s)
+{
+    int i;
+
+    s->reg = 0;
+    for (i = 0; i < ESCC_SERIAL_REGS; i++) {
+        s->rregs[i] = 0;
+        s->wregs[i] = 0;
+    }
+    /* 1X divisor, 1 stop bit, no parity */
+    s->wregs[W_TXCTRL1] = TXCTRL1_1STOP;
+    s->wregs[W_MINTR] = MINTR_RST_ALL;
+    /* Synch mode tx clock = TRxC */
+    s->wregs[W_CLOCK] = CLOCK_TRXC;
+    /* PLL disabled */
+    s->wregs[W_MISC2] = MISC2_PLLDIS;
+    /* Enable most interrupts */
+    s->wregs[W_EXTINT] = EXTINT_DCD | EXTINT_SYNCINT | EXTINT_CTSINT |
+                         EXTINT_TXUNDRN | EXTINT_BRKINT;
+    if (s->disabled) {
+        s->rregs[R_STATUS] = STATUS_TXEMPTY | STATUS_DCD | STATUS_SYNC |
+                             STATUS_CTS | STATUS_TXUNDRN;
+    } else {
+        s->rregs[R_STATUS] = STATUS_TXEMPTY | STATUS_TXUNDRN;
+    }
+    s->rregs[R_SPEC] = SPEC_BITS8 | SPEC_ALLSENT;
+
+    s->rx = s->tx = 0;
+    s->rxint = s->txint = 0;
+    s->rxint_under_svc = s->txint_under_svc = 0;
+    s->e0_mode = s->led_mode = s->caps_lock_mode = s->num_lock_mode = 0;
+    clear_queue(s);
+}
+
 static void escc_reset(DeviceState *d)
 {
     ESCCState *s = ESCC(d);
@@ -547,10 +581,12 @@ static void escc_mem_write(void *opaque, hwaddr addr,
             default:
                 break;
             case MINTR_RST_B:
-                escc_reset_chn(&serial->chn[0]);
+                trace_escc_soft_reset_chn(CHN_C(&serial->chn[0]));
+                escc_soft_reset_chn(&serial->chn[0]);
                 return;
             case MINTR_RST_A:
-                escc_reset_chn(&serial->chn[1]);
+                trace_escc_soft_reset_chn(CHN_C(&serial->chn[1]));
+                escc_soft_reset_chn(&serial->chn[1]);
                 return;
             case MINTR_RST_ALL:
                 escc_reset(DEVICE(serial));