From nobody Thu Jul 10 07:44:50 2025 Delivered-To: importer2@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+importer2=patchew.org@nongnu.org; dmarc=pass(p=none dis=none) header.from=linux.microsoft.com ARC-Seal: i=1; a=rsa-sha256; t=1674491106; cv=none; d=zohomail.com; s=zohoarc; b=SK7Zw8j6D/juIuJV6c8X3E7SDTZVTzKZcGtAApTtO5/tJxgK3/3VUDei2FTFisbv4X5rP0M+f3Vt6D2yOaVns8vMt7b4VNcLJJimEvYNLAU6VNCHvJU3E/INDm7ScobiXu3u1HGF+iSjDdeVb5Vq4KKufXy+WCZT8C9QjYrKC8g= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1674491106; h=Content-Type:Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=4oqNjtWV5XHXopxp73MULIexxMjPeEHnzsjLi/LM2aU=; b=dd+GtNAazfAMenHGtgokWsVK4OYk8d9k0CkbQ83frtEMs3IpP7YFKu59FJK3xHWIERFirbpy3gtNykY+AMhgcdrdX6mX2FplE2FPXdTvQP9OuRiE++wNGWGD120U1KbuxI7fsRNxG2IsDalJ/j9syaaKWVfLJDy1DVfT7WDUKA4= 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+importer2=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 167449110602347.72614844361647; Mon, 23 Jan 2023 08:25:06 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pJzbL-0007eE-Od; Mon, 23 Jan 2023 11:23:19 -0500 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 1pJzbH-0007b5-Ps; Mon, 23 Jan 2023 11:23:15 -0500 Received: from linux.microsoft.com ([13.77.154.182]) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pJzbF-0003aN-Sn; Mon, 23 Jan 2023 11:23:15 -0500 Received: from localhost.localdomain (unknown [77.64.253.114]) by linux.microsoft.com (Postfix) with ESMTPSA id 3ECD420E2C01; Mon, 23 Jan 2023 08:23:11 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 3ECD420E2C01 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1674490992; bh=4oqNjtWV5XHXopxp73MULIexxMjPeEHnzsjLi/LM2aU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=i7c8nd9eequBlWd1HiYBDQ6SlvXognEiwNvZI57YZubC27nQTzGtyz7CGdHIvOlQ7 aodEi64nWve9XjG2K92gN6xmCaWZlRSyUvHXckA2qy7VNE9ANLzIiW/4yrCWMyA/Z3 Z2dAXDtBV/mEocWKr4HaG5WjdOlaLYWhjRbOUvbE= From: Evgeny Iakovlev To: qemu-arm@nongnu.org Cc: qemu-devel@nongnu.org, peter.maydell@linaro.org, philmd@linaro.org Subject: [PATCH v4 1/5] hw/char/pl011: refactor FIFO depth handling code Date: Mon, 23 Jan 2023 17:23:00 +0100 Message-Id: <20230123162304.26254-2-eiakovlev@linux.microsoft.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230123162304.26254-1-eiakovlev@linux.microsoft.com> References: <20230123162304.26254-1-eiakovlev@linux.microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" 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+importer2=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=13.77.154.182; envelope-from=eiakovlev@linux.microsoft.com; helo=linux.microsoft.com X-Spam_score_int: -197 X-Spam_score: -19.8 X-Spam_bar: ------------------- X-Spam_report: (-19.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, ENV_AND_HDR_SPF_MATCH=-0.5, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, USER_IN_DEF_DKIM_WL=-7.5, USER_IN_DEF_SPF_WL=-7.5 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+importer2=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer2=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @linux.microsoft.com) X-ZM-MESSAGEID: 1674491107908100003 PL011 can be in either of 2 modes depending guest config: FIFO and single register. The last mode could be viewed as a 1-element-deep FIFO. Current code open-codes a bunch of depth-dependent logic. Refactor FIFO depth handling code to isolate calculating current FIFO depth. One functional (albeit guest-invisible) side-effect of this change is that previously we would always increment s->read_pos in UARTDR read handler even if FIFO was disabled, now we are limiting read_pos to not exceed FIFO depth (read_pos itself is reset to 0 if user disables FIFO). Signed-off-by: Evgeny Iakovlev Reviewed-by: Peter Maydell Reviewed-by: Philippe Mathieu-Daud=C3=A9 --- hw/char/pl011.c | 30 ++++++++++++++++++------------ include/hw/char/pl011.h | 5 ++++- 2 files changed, 22 insertions(+), 13 deletions(-) diff --git a/hw/char/pl011.c b/hw/char/pl011.c index c076813423..3fa3b75d04 100644 --- a/hw/char/pl011.c +++ b/hw/char/pl011.c @@ -81,6 +81,17 @@ static void pl011_update(PL011State *s) } } =20 +static bool pl011_is_fifo_enabled(PL011State *s) +{ + return (s->lcr & 0x10) !=3D 0; +} + +static inline unsigned pl011_get_fifo_depth(PL011State *s) +{ + /* Note: FIFO depth is expected to be power-of-2 */ + return pl011_is_fifo_enabled(s) ? PL011_FIFO_DEPTH : 1; +} + static uint64_t pl011_read(void *opaque, hwaddr offset, unsigned size) { @@ -94,8 +105,7 @@ static uint64_t pl011_read(void *opaque, hwaddr offset, c =3D s->read_fifo[s->read_pos]; if (s->read_count > 0) { s->read_count--; - if (++s->read_pos =3D=3D 16) - s->read_pos =3D 0; + s->read_pos =3D (s->read_pos + 1) & (pl011_get_fifo_depth(s) -= 1); } if (s->read_count =3D=3D 0) { s->flags |=3D PL011_FLAG_RXFE; @@ -273,11 +283,7 @@ static int pl011_can_receive(void *opaque) PL011State *s =3D (PL011State *)opaque; int r; =20 - if (s->lcr & 0x10) { - r =3D s->read_count < 16; - } else { - r =3D s->read_count < 1; - } + r =3D s->read_count < pl011_get_fifo_depth(s); trace_pl011_can_receive(s->lcr, s->read_count, r); return r; } @@ -286,15 +292,15 @@ static void pl011_put_fifo(void *opaque, uint32_t val= ue) { PL011State *s =3D (PL011State *)opaque; int slot; + unsigned pipe_depth; =20 - slot =3D s->read_pos + s->read_count; - if (slot >=3D 16) - slot -=3D 16; + pipe_depth =3D pl011_get_fifo_depth(s); + slot =3D (s->read_pos + s->read_count) & (pipe_depth - 1); s->read_fifo[slot] =3D value; s->read_count++; s->flags &=3D ~PL011_FLAG_RXFE; trace_pl011_put_fifo(value, s->read_count); - if (!(s->lcr & 0x10) || s->read_count =3D=3D 16) { + if (s->read_count =3D=3D pipe_depth) { trace_pl011_put_fifo_full(); s->flags |=3D PL011_FLAG_RXFF; } @@ -359,7 +365,7 @@ static const VMStateDescription vmstate_pl011 =3D { VMSTATE_UINT32(dmacr, PL011State), VMSTATE_UINT32(int_enabled, PL011State), VMSTATE_UINT32(int_level, PL011State), - VMSTATE_UINT32_ARRAY(read_fifo, PL011State, 16), + VMSTATE_UINT32_ARRAY(read_fifo, PL011State, PL011_FIFO_DEPTH), VMSTATE_UINT32(ilpr, PL011State), VMSTATE_UINT32(ibrd, PL011State), VMSTATE_UINT32(fbrd, PL011State), diff --git a/include/hw/char/pl011.h b/include/hw/char/pl011.h index dc2c90eedc..926322e242 100644 --- a/include/hw/char/pl011.h +++ b/include/hw/char/pl011.h @@ -27,6 +27,9 @@ OBJECT_DECLARE_SIMPLE_TYPE(PL011State, PL011) /* This shares the same struct (and cast macro) as the base pl011 device */ #define TYPE_PL011_LUMINARY "pl011_luminary" =20 +/* Depth of UART FIFO in bytes, when FIFO mode is enabled (else depth =3D= =3D 1) */ +#define PL011_FIFO_DEPTH 16 + struct PL011State { SysBusDevice parent_obj; =20 @@ -39,7 +42,7 @@ struct PL011State { uint32_t dmacr; uint32_t int_enabled; uint32_t int_level; - uint32_t read_fifo[16]; + uint32_t read_fifo[PL011_FIFO_DEPTH]; uint32_t ilpr; uint32_t ibrd; uint32_t fbrd; --=20 2.34.1