From 9d248a4be524a6c820634e9b58e79085972cb78f Mon Sep 17 00:00:00 2001 From: Mark Cave-Ayland Date: Fri, 3 Sep 2021 12:32:16 +0100 Subject: [PATCH] escc: reset register values to zero in escc_reset() This is to ensure that a device reset always returns the ESCC to a known state. Note that this is currently redundant with the same code in escc_reset_chn() but that will change shortly. Signed-off-by: Mark Cave-Ayland Reviewed-by: Peter Maydell Message-Id: <20210903113223.19551-3-mark.cave-ayland@ilande.co.uk> Signed-off-by: Mark Cave-Ayland --- hw/char/escc.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/hw/char/escc.c b/hw/char/escc.c index c87ecd59d8..b0d3b92dc1 100644 --- a/hw/char/escc.c +++ b/hw/char/escc.c @@ -300,9 +300,24 @@ static void escc_reset_chn(ESCCChannelState *s) static void escc_reset(DeviceState *d) { ESCCState *s = ESCC(d); + int i, j; - escc_reset_chn(&s->chn[0]); - escc_reset_chn(&s->chn[1]); + for (i = 0; i < 2; i++) { + ESCCChannelState *cs = &s->chn[i]; + + /* + * According to the ESCC datasheet "Miscellaneous Questions" section + * on page 384, the values of the ESCC registers are not guaranteed on + * power-on until an explicit hardware or software reset has been + * issued. For now we zero the registers so that a device reset always + * returns the emulated device to a fixed state. + */ + for (j = 0; j < ESCC_SERIAL_REGS; j++) { + cs->rregs[j] = 0; + cs->wregs[j] = 0; + } + escc_reset_chn(cs); + } } static inline void set_rxint(ESCCChannelState *s)