From patchwork Mon Sep 19 15:08:46 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Sergiu Moga X-Patchwork-Id: 12980624 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 D72C6C6FA86 for ; Mon, 19 Sep 2022 15:14:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229929AbiISPO5 (ORCPT ); Mon, 19 Sep 2022 11:14:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33668 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229887AbiISPOd (ORCPT ); Mon, 19 Sep 2022 11:14:33 -0400 Received: from esa.microchip.iphmx.com (esa.microchip.iphmx.com [68.232.154.123]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C0ADE356FA; Mon, 19 Sep 2022 08:14:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=microchip.com; i=@microchip.com; q=dns/txt; s=mchp; t=1663600455; x=1695136455; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=ZdF5SM4cO4qp59VQ1wleOscxihQfsANgHden/vCDiF4=; b=MmgsBaIzaLoN02eMZ7PgukOVFm3mNw+YdGrmjmCr6NpttSxexYQscSmP bkWeAzBAdGLlCWCgcIg+Dstep2H69XBJwfezFVufLYoU8GET5BueqLvMH FBpOsu5eQVFdb8CI8+yrR4mxHVrB7Jr30U0IS4l9QHp8BBc/jyCzaKDlT +6MgsFLWh9I+TdOOTJ4j7nVltaTAdeQcCzsyQQoFCAkQQoYDrzNqgU2kf zSse+tX8Ywnxza6fdQXa0HZ9pYO7Bdm1rFDoc5GA2RbBb0HL210BCT+0m FlJeonOuxZteJX9lGUyMmK20RtyZYuBaPV0OmtKjNxC3oNN0fkEHuzbJ9 g==; X-IronPort-AV: E=Sophos;i="5.93,328,1654585200"; d="scan'208";a="114368344" Received: from unknown (HELO email.microchip.com) ([170.129.1.10]) by esa6.microchip.iphmx.com with ESMTP/TLS/AES256-SHA256; 19 Sep 2022 08:14:14 -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; Mon, 19 Sep 2022 08:14:13 -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; Mon, 19 Sep 2022 08:14:09 -0700 From: Sergiu Moga To: , , , , , , , , , , CC: , , , , , Sergiu Moga Subject: [PATCH v4 8/9] tty: serial: atmel: Only divide Clock Divisor if the IP is USART Date: Mon, 19 Sep 2022 18:08:46 +0300 Message-ID: <20220919150846.1148783-9-sergiu.moga@microchip.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220919150846.1148783-1-sergiu.moga@microchip.com> References: <20220919150846.1148783-1-sergiu.moga@microchip.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-spi@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 Reviewed-by: Ilpo Järvinen --- 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] v3 -> v4: - Use min_t instead of & - Previously [PATCH 12] 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..c983798a4ab2 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 = min_t(unsigned int, cd, ATMEL_US_CD); } + quot = cd | fp << ATMEL_US_FP_OFFSET; if (!(port->iso7816.flags & SER_ISO7816_ENABLED))