From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3F1CDC43334 for ; Tue, 7 Jun 2022 08:30:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238234AbiFGIaQ (ORCPT ); Tue, 7 Jun 2022 04:30:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42874 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238214AbiFGI3x (ORCPT ); Tue, 7 Jun 2022 04:29:53 -0400 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C0EB2692A0; Tue, 7 Jun 2022 01:29:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1654590592; x=1686126592; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=DP/onAIOrmF3FhzAcZp5ZbJX2/7KPt1IAKsKqjs5ImQ=; b=d5tDtize1EwN1/fx8OnogKuNXy0r1CsTBawDEfoH0VWxyCrbU/IOqYyz JF9O1cM2tsD7yLRf2uWry/GdfHjraR7CPgUX5Fw/FIDOUVzkUVQH4eTyp i5JnHwcYXV+0P5b9v/s4vpp2cWLdZFfo+R+wjWpsCpX0wS1NN7uR0nMrH 1Riao3gg3/dzKxdDBncAllY0qMr/6WB/UkRo5PATUJRJuqSqygt4gNcAE ywNLYUBGysKH0BOegrot1bUKWnHZCgD3md/hTII1samTcOggYxEFcqb1N sBY2CrLAsW3UJPBMBqXu2WIKm5Ja2nmVERMxX7YyALiIePiY1Ertdmdoz w==; X-IronPort-AV: E=McAfee;i="6400,9594,10370"; a="277393630" X-IronPort-AV: E=Sophos;i="5.91,283,1647327600"; d="scan'208";a="277393630" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Jun 2022 01:29:52 -0700 X-IronPort-AV: E=Sophos;i="5.91,283,1647327600"; d="scan'208";a="584103475" Received: from akmessan-mobl1.amr.corp.intel.com (HELO ijarvine-MOBL2.ger.corp.intel.com) ([10.251.214.146]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Jun 2022 01:29:50 -0700 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= To: linux-serial@vger.kernel.org, Greg KH , Jiri Slaby , Andy Shevchenko , =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= , linux-kernel@vger.kernel.org Cc: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Subject: [PATCH v3 2/6] serial: 8250: Create serial_lsr_in() Date: Tue, 7 Jun 2022 11:29:30 +0300 Message-Id: <20220607082934.7242-3-ilpo.jarvinen@linux.intel.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220607082934.7242-1-ilpo.jarvinen@linux.intel.com> References: <20220607082934.7242-1-ilpo.jarvinen@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org LSR register readers need to be careful in order to not lose bits that are not preserved across reads. Create a helper that takes care of storing the non-preserved bits into lsr_save_flags. Signed-off-by: Ilpo Järvinen --- drivers/tty/serial/8250/8250.h | 20 ++++++++++++++++++++ drivers/tty/serial/8250/8250_core.c | 3 +-- drivers/tty/serial/8250/8250_port.c | 15 ++++----------- 3 files changed, 25 insertions(+), 13 deletions(-) diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h index 3d9a7e539dea..b120da57c61f 100644 --- a/drivers/tty/serial/8250/8250.h +++ b/drivers/tty/serial/8250/8250.h @@ -123,6 +123,26 @@ static inline void serial_out(struct uart_8250_port *up, int offset, int value) up->port.serial_out(&up->port, offset, value); } +/** + * serial_lsr_in - Read LSR register and preserve flags across reads + * @up: uart 8250 port + * + * Read LSR register and handle saving non-preserved flags across reads. + * The flags that are not preserved across reads are stored into + * up->lsr_saved_flags. + * + * Returns LSR value or'ed with the preserved flags (if any). + */ +static inline unsigned int serial_lsr_in(struct uart_8250_port *up) +{ + unsigned int lsr = up->lsr_saved_flags; + + lsr |= serial_in(up, UART_LSR); + up->lsr_saved_flags = lsr & LSR_SAVE_FLAGS; + + return lsr; +} + /* * For the 16C950 */ diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c index 12c5e5d0ce6d..90ddc8924811 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -276,8 +276,7 @@ static void serial8250_backup_timeout(struct timer_list *t) * the "Diva" UART used on the management processor on many HP * ia64 and parisc boxes. */ - lsr = serial_in(up, UART_LSR); - up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS; + lsr = serial_lsr_in(up); if ((iir & UART_IIR_NO_INT) && (up->ier & UART_IER_THRI) && (!uart_circ_empty(&up->port.state->xmit) || up->port.x_char) && (lsr & UART_LSR_THRE)) { diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index c5e0f925f4b6..ec5abeb638eb 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -1508,11 +1508,9 @@ static inline void __stop_tx(struct uart_8250_port *p) struct uart_8250_em485 *em485 = p->em485; if (em485) { - unsigned char lsr = serial_in(p, UART_LSR); + unsigned char lsr = serial_lsr_in(p); u64 stop_delay = 0; - p->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS; - if (!(lsr & UART_LSR_THRE)) return; /* @@ -1567,10 +1565,8 @@ static inline void __start_tx(struct uart_port *port) if (serial8250_set_THRI(up)) { if (up->bugs & UART_BUG_TXEN) { - unsigned char lsr; + unsigned char lsr = serial_lsr_in(up); - lsr = serial_in(up, UART_LSR); - up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS; if (lsr & UART_LSR_THRE) serial8250_tx_chars(up); } @@ -2001,8 +1997,7 @@ static unsigned int serial8250_tx_empty(struct uart_port *port) serial8250_rpm_get(up); spin_lock_irqsave(&port->lock, flags); - lsr = serial_port_in(port, UART_LSR); - up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS; + lsr = serial_lsr_in(up); spin_unlock_irqrestore(&port->lock, flags); serial8250_rpm_put(up); @@ -2078,9 +2073,7 @@ static void wait_for_lsr(struct uart_8250_port *up, int bits) /* Wait up to 10ms for the character(s) to be sent. */ for (;;) { - status = serial_in(up, UART_LSR); - - up->lsr_saved_flags |= status & LSR_SAVE_FLAGS; + status = serial_lsr_in(up); if ((status & bits) == bits) break; -- 2.30.2