From patchwork Tue Sep 13 14:22:04 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sergiu Moga X-Patchwork-Id: 605678 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 893DBC6FA82 for ; Tue, 13 Sep 2022 14:59:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234756AbiIMO7v (ORCPT ); Tue, 13 Sep 2022 10:59:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38058 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235119AbiIMO7Q (ORCPT ); Tue, 13 Sep 2022 10:59:16 -0400 Received: from esa.microchip.iphmx.com (esa.microchip.iphmx.com [68.232.153.233]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 263457434D; Tue, 13 Sep 2022 07:28:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=microchip.com; i=@microchip.com; q=dns/txt; s=mchp; t=1663079318; x=1694615318; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=IAvz+EPRVJUa2sWHwWF/4LgxqmMeTJl/Cd8xvZqLdzA=; b=DuTbcKJYCsBH6ALs5uDL8+qarqKM5HvWdZNN6iI/25wCqslpsH2tLj+E 6nKlsuqMLNus1lEWxuMR4n2eOyUEyz+tFookFS+x81/ihjSZnzhfwkfP8 J2Loona3UkR70WkyqrxcCgZ24G3W0Erm5ek5h3KdRri79GklhgsDy1MxA gUAVAIyT+YW16Y/pVU4aIvtR/1Ce/sIlemfReBsZMyvDvgzTunLFAiHt3 pYqZ5iCqckpHAUorNmkEvoYmogQtD23WycXwafSlWp+u7EDzDsCue+/JR O99jzO4Wti0ii61nRu7IxDIFzQa4Ab3bghg9fzT7ARm3z5GpzhipD/ilk A==; X-IronPort-AV: E=Sophos;i="5.93,313,1654585200"; d="scan'208";a="180313680" Received: from unknown (HELO email.microchip.com) ([170.129.1.10]) by esa3.microchip.iphmx.com with ESMTP/TLS/AES256-SHA256; 13 Sep 2022 07:25:57 -0700 Received: from chn-vm-ex03.mchp-main.com (10.10.85.151) by chn-vm-ex04.mchp-main.com (10.10.85.152) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.12; Tue, 13 Sep 2022 07:25:48 -0700 Received: from ROB-ULT-M68701.microchip.com (10.10.115.15) by chn-vm-ex03.mchp-main.com (10.10.85.151) with Microsoft SMTP Server id 15.1.2507.12 via Frontend Transport; Tue, 13 Sep 2022 07:25:43 -0700 From: Sergiu Moga To: , , , , , , , , , , , , , , , , CC: , , , , , Subject: [PATCH v3 12/14] tty: serial: atmel: Only divide Clock Divisor if the IP is USART Date: Tue, 13 Sep 2022 17:22:04 +0300 Message-ID: <20220913142205.162399-13-sergiu.moga@microchip.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220913142205.162399-1-sergiu.moga@microchip.com> References: <20220913142205.162399-1-sergiu.moga@microchip.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org Make sure that the driver only divides the clock divisor if the IP handled at that point is USART, since UART IP's do not support implicit peripheral clock division. Instead, in the case of UART, go with the highest possible clock divisor. Signed-off-by: Sergiu Moga --- v1 -> v2: - Nothing, this patch was not here before and is mainly meant as both cleanup and as a way to introduce a new field into struct atmel_uart_port that will be used by the last patch to diferentiate between USART and UART regarding the location of the Baudrate Clock Source bitmask. v2 -> v3: - Use ATMEL_US_CD instead of 65535 - Previously [PATCH 10] drivers/tty/serial/atmel_serial.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index ab4a9dfae07d..ad7483230090 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -150,6 +150,7 @@ struct atmel_uart_port { u32 rts_low; bool ms_irq_enabled; u32 rtor; /* address of receiver timeout register if it exists */ + bool is_usart; bool has_frac_baudrate; bool has_hw_timer; struct timer_list uart_timer; @@ -1825,6 +1826,7 @@ static void atmel_get_ip_name(struct uart_port *port) */ atmel_port->has_frac_baudrate = false; atmel_port->has_hw_timer = false; + atmel_port->is_usart = false; if (name == new_uart) { dev_dbg(port->dev, "Uart with hw timer"); @@ -1834,6 +1836,7 @@ static void atmel_get_ip_name(struct uart_port *port) dev_dbg(port->dev, "Usart\n"); atmel_port->has_frac_baudrate = true; atmel_port->has_hw_timer = true; + atmel_port->is_usart = true; atmel_port->rtor = ATMEL_US_RTOR; version = atmel_uart_readl(port, ATMEL_US_VERSION); switch (version) { @@ -1863,6 +1866,7 @@ static void atmel_get_ip_name(struct uart_port *port) dev_dbg(port->dev, "This version is usart\n"); atmel_port->has_frac_baudrate = true; atmel_port->has_hw_timer = true; + atmel_port->is_usart = true; atmel_port->rtor = ATMEL_US_RTOR; break; case 0x203: @@ -2283,10 +2287,21 @@ static void atmel_set_termios(struct uart_port *port, cd = uart_get_divisor(port, baud); } - if (cd > 65535) { /* BRGR is 16-bit, so switch to slower clock */ + /* + * If the current value of the Clock Divisor surpasses the 16 bit + * ATMEL_US_CD mask and the IP is USART, switch to the Peripheral + * Clock implicitly divided by 8. + * If the IP is UART however, keep the highest possible value for + * the CD and avoid needless division of CD, since UART IP's do not + * support implicit division of the Peripheral Clock. + */ + if (atmel_port->is_usart && cd > ATMEL_US_CD) { cd /= 8; mode |= ATMEL_US_USCLKS_MCK_DIV8; + } else { + cd &= ATMEL_US_CD; } + quot = cd | fp << ATMEL_US_FP_OFFSET; if (!(port->iso7816.flags & SER_ISO7816_ENABLED))