From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48456) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ffRZH-00059X-Va for qemu-devel@nongnu.org; Tue, 17 Jul 2018 11:07:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ffRZG-0007Fh-GO for qemu-devel@nongnu.org; Tue, 17 Jul 2018 11:07:11 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:54088 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ffRZG-0007FT-B8 for qemu-devel@nongnu.org; Tue, 17 Jul 2018 11:07:10 -0400 From: Paolo Bonzini Date: Tue, 17 Jul 2018 17:06:48 +0200 Message-Id: <1531840015-28804-7-git-send-email-pbonzini@redhat.com> In-Reply-To: <1531840015-28804-1-git-send-email-pbonzini@redhat.com> References: <1531840015-28804-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PULL 06/13] PC Chipset: Improve serial divisor calculation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Calvin Lee From: Calvin Lee This fixes several problems I found in the UART serial implementation. Now all divisor values are allowed, while before divisor values of zero and below the base baud rate were rejected. All changes are in reference to http://www.sci.muni.cz/docs/pc/serport.txt Signed-off-by: Calvin Lee Message-Id: <20180512000545.966-2-cyrus296@gmail.com> Signed-off-by: Paolo Bonzini --- hw/char/serial.c | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-) diff --git a/hw/char/serial.c b/hw/char/serial.c index cd7d747..d3b75f0 100644 --- a/hw/char/serial.c +++ b/hw/char/serial.c @@ -150,13 +150,10 @@ static void serial_update_irq(SerialState *s) static void serial_update_parameters(SerialState *s) { - int speed, parity, data_bits, stop_bits, frame_size; + float speed; + int parity, data_bits, stop_bits, frame_size; QEMUSerialSetParams ssp; - if (s->divider == 0 || s->divider > s->baudbase) { - return; - } - /* Start bit. */ frame_size = 1; if (s->lcr & 0x08) { @@ -169,14 +166,16 @@ static void serial_update_parameters(SerialState *s) } else { parity = 'N'; } - if (s->lcr & 0x04) + if (s->lcr & 0x04) { stop_bits = 2; - else + } else { stop_bits = 1; + } data_bits = (s->lcr & 0x03) + 5; frame_size += data_bits + stop_bits; - speed = s->baudbase / s->divider; + /* Zero divisor should give about 3500 baud */ + speed = (s->divider == 0) ? 3500 : (float) s->baudbase / s->divider; ssp.speed = speed; ssp.parity = parity; ssp.data_bits = data_bits; @@ -184,7 +183,7 @@ static void serial_update_parameters(SerialState *s) s->char_transmit_time = (NANOSECONDS_PER_SECOND / speed) * frame_size; qemu_chr_fe_ioctl(&s->chr, CHR_IOCTL_SERIAL_SET_PARAMS, &ssp); - DPRINTF("speed=%d parity=%c data=%d stop=%d\n", + DPRINTF("speed=%.2f parity=%c data=%d stop=%d\n", speed, parity, data_bits, stop_bits); } @@ -341,7 +340,11 @@ static void serial_ioport_write(void *opaque, hwaddr addr, uint64_t val, default: case 0: if (s->lcr & UART_LCR_DLAB) { - s->divider = (s->divider & 0xff00) | val; + if (size == 2) { + s->divider = (s->divider & 0xff00) | val; + } else if (size == 4) { + s->divider = val; + } serial_update_parameters(s); } else { s->thr = (uint8_t) val; -- 1.8.3.1