From patchwork Wed Jun 8 09:54:27 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Ilpo_J=C3=A4rvinen?= X-Patchwork-Id: 580195 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 15FD9C433EF for ; Wed, 8 Jun 2022 10:10:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235827AbiFHKK0 (ORCPT ); Wed, 8 Jun 2022 06:10:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42264 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235934AbiFHKJk (ORCPT ); Wed, 8 Jun 2022 06:09:40 -0400 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B839B1D5AA1; Wed, 8 Jun 2022 02:54:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1654682097; x=1686218097; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=GeRNMr3HZUhOZVt9G+fJ5knQmLzUpmCXYoXf8y44tOw=; b=kIEEuK7Pan80vXJZcuJOPUKJx1i5WI59IuQ3/7cmDI20kxqwIfIpq4lu 6bK8/KS0RI52eg30KvTIsvsQd7Dbj3O1z+xQaB9b9AyrfGP+Ngn8tjDTf HEg5Xiiy30NlON2Z7JmpQ59AJ+QOv+se5TbqMblLA+Ciun3TwkXigQYFz 9/0/wK/6PLHNd8JF4EUczmwGcE8TVVAGBLBeprvS3DqenDQRYOPxhDZOQ qyzPKEUWeG8NKoSkfyC+34F2DNu+/9dKXl++Rz2GL4+TwieOgsSdlLUFG 2LrmmjiECoF2Ndx6Br2nd77BFppx7tmFaf3FbbU+EMsI3J1JgppSFbbYF g==; X-IronPort-AV: E=McAfee;i="6400,9594,10371"; a="278019533" X-IronPort-AV: E=Sophos;i="5.91,286,1647327600"; d="scan'208";a="278019533" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jun 2022 02:54:49 -0700 X-IronPort-AV: E=Sophos;i="5.91,286,1647327600"; d="scan'208";a="584783446" Received: from bmichals-mobl.ger.corp.intel.com (HELO ijarvine-MOBL2.ger.corp.intel.com) ([10.252.57.131]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jun 2022 02:54:47 -0700 From: =?utf-8?q?Ilpo_J=C3=A4rvinen?= To: linux-serial@vger.kernel.org, Greg KH , Jiri Slaby , Andy Shevchenko , =?utf-8?q?Uwe_Kleine-K?= =?utf-8?q?=C3=B6nig?= , linux-kernel@vger.kernel.org Cc: =?utf-8?q?Ilpo_J=C3=A4rvinen?= , Andy Shevchenko Subject: [PATCH v4 2/6] serial: 8250: Create serial_lsr_in() Date: Wed, 8 Jun 2022 12:54:27 +0300 Message-Id: <20220608095431.18376-3-ilpo.jarvinen@linux.intel.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220608095431.18376-1-ilpo.jarvinen@linux.intel.com> References: <20220608095431.18376-1-ilpo.jarvinen@linux.intel.com> MIME-Version: 1.0 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. Reviewed-by: Andy Shevchenko 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;