From nobody Sun Nov 24 08:00:25 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=none dis=none) header.from=gmail.com ARC-Seal: i=1; a=rsa-sha256; t=1725848052; cv=none; d=zohomail.com; s=zohoarc; b=UflvjUQZEDVPTSMhH7hKdpf6HKBj6YUVfy0GWBB053ekNq/Ehd4xH/6iyuE4sP20kWFY+9UGseQn9XwkNlUB+jCs1O4Tpcxp8jNSPu8pd0RQ+eBjbfVUuEozp2gYeDFB3mpmXZ6d8swLrL488MvTIf1vPKoDUQZhWszWPV9/DmA= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1725848052; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=7d2pKU/b/laqA6UDAi2cfTpZBwJfK0bU7UCihSBw02Q=; b=nZiNKR5dwcJFmAJ4h4sJ9M34MwX3r82LfnsWz2PuPTCFs1C52T2YclLdXop/orCIJoCpfNUOLIsPFXTT87QYVLIxNeesyNvbMEGZbvDIQ4s/Fkdk8j6POA8JpfdKdO/vAzQnHkRbu6tq0xHyL6CwTB8lP9o4+9vY34Y2XHRXKC4= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=none dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1725848052476837.9697090554887; Sun, 8 Sep 2024 19:14:12 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1snTuQ-0006yr-Sk; Sun, 08 Sep 2024 22:13:42 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1snTuQ-0006xz-3I; Sun, 08 Sep 2024 22:13:42 -0400 Received: from mail-pg1-x52e.google.com ([2607:f8b0:4864:20::52e]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1snTuO-0001NH-3b; Sun, 08 Sep 2024 22:13:41 -0400 Received: by mail-pg1-x52e.google.com with SMTP id 41be03b00d2f7-7d4fa972cbeso3045559a12.2; Sun, 08 Sep 2024 19:13:39 -0700 (PDT) Received: from toolbox.alistair23.me (2403-580b-97e8-0-82ce-f179-8a79-69f4.ip6.aussiebb.net. [2403:580b:97e8:0:82ce:f179:8a79:69f4]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-718e58c68d3sm2528155b3a.84.2024.09.08.19.13.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 08 Sep 2024 19:13:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1725848018; x=1726452818; darn=nongnu.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=7d2pKU/b/laqA6UDAi2cfTpZBwJfK0bU7UCihSBw02Q=; b=fs4yqPzecAbJ9oqowkM6UYmXPdXjgigvPgIQURLZXIBkvqgQwB/B/ImsWf3xjJo4nF Ac9Zu/OKGsgAmclJO1IfI1iUOqnjLeMGA2IP9Fr5q+FTfrN7Hxf6n5RPYlePM2gvhRQ+ 0mXMiSNszh9prX1BYPtmb6qS2YjoXo1/gqelf1bmCDgEJmj0agint5oCk9yKLqE5jYG3 /S6t8bLv45XzIqJoAtk8SqDv2sDVik6t5O8laLSMyar6acHP6al+dliPJeg1OaIBdAOX Am2uRAEgscj0iCsgc9hFlWTMg2tKnk6wk8xddulyL99M/8vXKEIeV86XHwbAGs5ePpcq HALw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1725848018; x=1726452818; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=7d2pKU/b/laqA6UDAi2cfTpZBwJfK0bU7UCihSBw02Q=; b=QkCUulibzFzcoXtU9zF1bKcMH+01gg74G5j9LfXCv2Oouiq53Qnz/nEhzWje4TcfME 2u1h0mnB4MrVA3lN5Y2uYUH8rzIHBgH9h0NNVz6FQQ/VjyaKECQAAO6rK+pluVNcYbAv xgLyjL1k3EGwk6K1RVPqI2urex16K7n0HwwzWmyRVvuoMJWiiXoeBjCdJj2Vc8iwcMuk DxuSXprh3YnLW5ve/KaLL9GxIeQrgaWnaBX7KDTm81blOFRrKdYnYt7BkZpUGzSdH4ZJ /C+IqcuBVm9FiOr/6hDBWsiBGpQyGfS494ORrCzLU3zQVDdx9V92Ns2G1Qn+reyRSEch a8FA== X-Forwarded-Encrypted: i=1; AJvYcCWEnbACzqu779WZ+BXIYla5lIeUWk1s/ZewEDJocG4Uj2QQm7OrgpTUT8SiUPHdkBbZogh++3RxwhJK@nongnu.org, AJvYcCWrjTRuscT9stU/H0mdLdI01BH5LFydDed28CzV1H3DWkjfe5247wbM8WXqwWP2kVisQ/x3Gch5k01fPA==@nongnu.org X-Gm-Message-State: AOJu0YwseRC0/oQPzZkyPDJ+G1FTbs4xjv+/1XHJl+Kfw5GsOSDHxCnv hiDhNJDGRNthDCJX3GiMffkK+bqNLYwnCexIrgTSJ4XiC/Q0vD/E X-Google-Smtp-Source: AGHT+IFqqsVVw8FYwbpFCiotNvA0Kd9BFDW1qfKJAcc4IIv7Jd5s9Kuw/JjiLE1KwMgR7Rk0grCeBQ== X-Received: by 2002:a05:6a21:58b:b0:1cf:2a85:722d with SMTP id adf61e73a8af0-1cf2a8573cdmr9342997637.3.1725848018223; Sun, 08 Sep 2024 19:13:38 -0700 (PDT) From: Alistair Francis X-Google-Original-From: Alistair Francis To: alex.bennee@linaro.org, qemu-devel@nongnu.org, peter.maydell@linaro.org Cc: dbarboza@ventanamicro.com, palmer@dabbelt.com, zhiwei_liu@linux.alibaba.com, qemu-riscv@nongnu.org, Paolo Bonzini , alistair23@gmail.com, Bin Meng , liwei1518@gmail.com, Alistair Francis , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , atishp@rivosinc.com, Alistair Francis , Thomas Huth Subject: [PATCH v3 2/2] hw/char: sifive_uart: Print uart characters async Date: Mon, 9 Sep 2024 12:13:17 +1000 Message-ID: <20240909021317.58192-3-alistair.francis@wdc.com> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240909021317.58192-1-alistair.francis@wdc.com> References: <20240909021317.58192-1-alistair.francis@wdc.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2607:f8b0:4864:20::52e; envelope-from=alistair23@gmail.com; helo=mail-pg1-x52e.google.com X-Spam_score_int: -17 X-Spam_score: -1.8 X-Spam_bar: - X-Spam_report: (-1.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_ENVFROM_END_DIGIT=0.25, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @gmail.com) X-ZM-MESSAGEID: 1725848054117116600 Content-Type: text/plain; charset="utf-8" The current approach of using qemu_chr_fe_write() and ignoring the return values results in dropped characters [1]. Let's update the SiFive UART to use a async sifive_uart_xmit() function to transmit the characters and apply back pressure to the guest with the SIFIVE_UART_TXFIFO_FULL status. This should avoid dropped characters and more realisticly model the hardware. 1: https://gitlab.com/qemu-project/qemu/-/issues/2114 Signed-off-by: Alistair Francis Tested-by: Thomas Huth Reviewed-by: Daniel Henrique Barboza --- include/hw/char/sifive_uart.h | 17 ++++++- hw/char/sifive_uart.c | 88 +++++++++++++++++++++++++++++++++-- 2 files changed, 99 insertions(+), 6 deletions(-) diff --git a/include/hw/char/sifive_uart.h b/include/hw/char/sifive_uart.h index 7f6c79f8bd..b43109bb8b 100644 --- a/include/hw/char/sifive_uart.h +++ b/include/hw/char/sifive_uart.h @@ -24,6 +24,7 @@ #include "hw/qdev-properties.h" #include "hw/sysbus.h" #include "qom/object.h" +#include "qemu/fifo8.h" =20 enum { SIFIVE_UART_TXFIFO =3D 0, @@ -48,9 +49,13 @@ enum { SIFIVE_UART_IP_RXWM =3D 2 /* Receive watermark interrupt pendin= g */ }; =20 +#define SIFIVE_UART_TXFIFO_FULL 0x80000000 + #define SIFIVE_UART_GET_TXCNT(txctrl) ((txctrl >> 16) & 0x7) #define SIFIVE_UART_GET_RXCNT(rxctrl) ((rxctrl >> 16) & 0x7) + #define SIFIVE_UART_RX_FIFO_SIZE 8 +#define SIFIVE_UART_TX_FIFO_SIZE 8 =20 #define TYPE_SIFIVE_UART "riscv.sifive.uart" OBJECT_DECLARE_SIMPLE_TYPE(SiFiveUARTState, SIFIVE_UART) @@ -63,13 +68,21 @@ struct SiFiveUARTState { qemu_irq irq; MemoryRegion mmio; CharBackend chr; - uint8_t rx_fifo[SIFIVE_UART_RX_FIFO_SIZE]; - uint8_t rx_fifo_len; + + uint32_t txfifo; uint32_t ie; uint32_t ip; uint32_t txctrl; uint32_t rxctrl; uint32_t div; + + uint8_t rx_fifo[SIFIVE_UART_RX_FIFO_SIZE]; + uint8_t rx_fifo_len; + + Fifo8 tx_fifo; + + QEMUTimer *fifo_trigger_handle; + uint64_t char_tx_time; }; =20 SiFiveUARTState *sifive_uart_create(MemoryRegion *address_space, hwaddr ba= se, diff --git a/hw/char/sifive_uart.c b/hw/char/sifive_uart.c index 7fc6787f69..ab899b60d6 100644 --- a/hw/char/sifive_uart.c +++ b/hw/char/sifive_uart.c @@ -64,6 +64,72 @@ static void sifive_uart_update_irq(SiFiveUARTState *s) } } =20 +static gboolean sifive_uart_xmit(void *do_not_use, GIOCondition cond, + void *opaque) +{ + SiFiveUARTState *s =3D opaque; + int ret; + const uint8_t *charecters; + uint32_t numptr =3D 0; + + /* instant drain the fifo when there's no back-end */ + if (!qemu_chr_fe_backend_connected(&s->chr)) { + fifo8_reset(&s->tx_fifo); + return G_SOURCE_REMOVE; + } + + if (fifo8_is_empty(&s->tx_fifo)) { + return G_SOURCE_REMOVE; + } + + /* Don't pop the FIFO in case the write fails */ + charecters =3D fifo8_peek_bufptr(&s->tx_fifo, + fifo8_num_used(&s->tx_fifo), &numptr); + ret =3D qemu_chr_fe_write(&s->chr, charecters, numptr); + + if (ret >=3D 0) { + /* We wrote the data, actually pop the fifo */ + fifo8_pop_bufptr(&s->tx_fifo, ret, NULL); + } + + if (!fifo8_is_empty(&s->tx_fifo)) { + guint r =3D qemu_chr_fe_add_watch(&s->chr, G_IO_OUT | G_IO_HUP, + sifive_uart_xmit, s); + if (!r) { + fifo8_reset(&s->tx_fifo); + return G_SOURCE_REMOVE; + } + } + + /* Clear the TX Full bit */ + if (!fifo8_is_full(&s->tx_fifo)) { + s->txfifo &=3D ~SIFIVE_UART_TXFIFO_FULL; + } + + sifive_uart_update_irq(s); + return G_SOURCE_REMOVE; +} + +static void sifive_uart_write_tx_fifo(SiFiveUARTState *s, const uint8_t *b= uf, + int size) +{ + uint64_t current_time =3D qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); + + if (size > fifo8_num_free(&s->tx_fifo)) { + size =3D fifo8_num_free(&s->tx_fifo); + qemu_log_mask(LOG_GUEST_ERROR, "sifive_uart: TX FIFO overflow"); + } + + fifo8_push_all(&s->tx_fifo, buf, size); + + if (fifo8_is_full(&s->tx_fifo)) { + s->txfifo |=3D SIFIVE_UART_TXFIFO_FULL; + } + + timer_mod(s->fifo_trigger_handle, current_time + + (s->char_tx_time * 4)); +} + static uint64_t sifive_uart_read(void *opaque, hwaddr addr, unsigned int size) { @@ -82,7 +148,7 @@ sifive_uart_read(void *opaque, hwaddr addr, unsigned int= size) return 0x80000000; =20 case SIFIVE_UART_TXFIFO: - return 0; /* Should check tx fifo */ + return s->txfifo; case SIFIVE_UART_IE: return s->ie; case SIFIVE_UART_IP: @@ -106,12 +172,10 @@ sifive_uart_write(void *opaque, hwaddr addr, { SiFiveUARTState *s =3D opaque; uint32_t value =3D val64; - unsigned char ch =3D value; =20 switch (addr) { case SIFIVE_UART_TXFIFO: - qemu_chr_fe_write(&s->chr, &ch, 1); - sifive_uart_update_irq(s); + sifive_uart_write_tx_fifo(s, (uint8_t *) &value, 1); return; case SIFIVE_UART_IE: s->ie =3D val64; @@ -131,6 +195,13 @@ sifive_uart_write(void *opaque, hwaddr addr, __func__, (int)addr, (int)value); } =20 +static void fifo_trigger_update(void *opaque) +{ + SiFiveUARTState *s =3D opaque; + + sifive_uart_xmit(NULL, G_IO_OUT, s); +} + static const MemoryRegionOps sifive_uart_ops =3D { .read =3D sifive_uart_read, .write =3D sifive_uart_write, @@ -197,6 +268,9 @@ static void sifive_uart_realize(DeviceState *dev, Error= **errp) { SiFiveUARTState *s =3D SIFIVE_UART(dev); =20 + s->fifo_trigger_handle =3D timer_new_ns(QEMU_CLOCK_VIRTUAL, + fifo_trigger_update, s); + qemu_chr_fe_set_handlers(&s->chr, sifive_uart_can_rx, sifive_uart_rx, sifive_uart_event, sifive_uart_be_change, s, NULL, true); @@ -206,12 +280,18 @@ static void sifive_uart_realize(DeviceState *dev, Err= or **errp) static void sifive_uart_reset_enter(Object *obj, ResetType type) { SiFiveUARTState *s =3D SIFIVE_UART(obj); + + s->txfifo =3D 0; s->ie =3D 0; s->ip =3D 0; s->txctrl =3D 0; s->rxctrl =3D 0; s->div =3D 0; + s->rx_fifo_len =3D 0; + + memset(s->rx_fifo, 0, SIFIVE_UART_RX_FIFO_SIZE); + fifo8_create(&s->tx_fifo, SIFIVE_UART_TX_FIFO_SIZE); } =20 static void sifive_uart_reset_hold(Object *obj, ResetType type) --=20 2.46.0