From patchwork Mon Apr 18 05:32:01 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Tu X-Patchwork-Id: 12816310 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 85B13C433F5 for ; Mon, 18 Apr 2022 05:33:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:CC:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=b+ok3eIht5lQ7Z/ZvqwDRGBnSSoKQi+3tjQH/01DGLY=; b=S3+QAw4+pzvWG8 HnZLuxmzP7AjRVl3LI9hNTomF/goFIQGyu0vk7Q0J/vJWAuhvZDynwVO8t6Y2jdca8xFrIsM0YH6A W5odjj2ETXXh8/lKJaMi8KcYb9H+rdTw5wKSxUeU87wfCeTIW9wSGqABlC0r7LO+QNOT68cvoG2GK mtBqXCXq95LGwIm3U7psisOCU0bGg+nIaJ6tFDupL/nhbyTgnrzlQQCldutjGh4yZLnDvZgc0khBY YRC7LEBg+TJsrFrEDhMKNBcSN7SP3ZKNJQjTiG2AwCQ1lJCdHJH+btcPrn5odE7YbblRJcDIGcW96 2CFn54gTnmLOj+cMwKuQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ngK18-00Fg7F-1C; Mon, 18 Apr 2022 05:33:42 +0000 Received: from mail-sh.amlogic.com ([58.32.228.43]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1ngK0q-00Fg2J-8l; Mon, 18 Apr 2022 05:33:25 +0000 Received: from droid06.amlogic.com (10.18.11.248) by mail-sh.amlogic.com (10.18.11.5) with Microsoft SMTP Server id 15.1.2176.14; Mon, 18 Apr 2022 13:33:23 +0800 From: Yu Tu To: , , , , Greg Kroah-Hartman , Neil Armstrong , Kevin Hilman , Jerome Brunet CC: Jiri Slaby , Martin Blumenstingl , Yu Tu Subject: [PATCH V2 1/2] tty: serial: meson: Add a 12MHz internal clock rate to calculate baud rate in order to meet the baud rate requirements of special BT modules Date: Mon, 18 Apr 2022 13:32:01 +0800 Message-ID: <20220418053202.24528-2-yu.tu@amlogic.com> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20220418053202.24528-1-yu.tu@amlogic.com> References: <20220418053202.24528-1-yu.tu@amlogic.com> MIME-Version: 1.0 X-Originating-IP: [10.18.11.248] X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220417_223324_324143_1B179DF2 X-CRM114-Status: GOOD ( 11.91 ) X-BeenThere: linux-amlogic@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-amlogic" Errors-To: linux-amlogic-bounces+linux-amlogic=archiver.kernel.org@lists.infradead.org A /2 divider over XTAL was introduced since G12A, and is preferred to be used over the still present /3 divider since it provides much closer frequencies vs the request baudrate.Especially the BT module uses 3Mhz baud rate. 8Mhz calculations can lead to baud rate bias, causing some problems. Signed-off-by: Yu Tu --- drivers/tty/serial/meson_uart.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c index 8e59624935af..58bd2723c004 100644 --- a/drivers/tty/serial/meson_uart.c +++ b/drivers/tty/serial/meson_uart.c @@ -68,6 +68,7 @@ #define AML_UART_BAUD_MASK 0x7fffff #define AML_UART_BAUD_USE BIT(23) #define AML_UART_BAUD_XTAL BIT(24) +#define AML_UART_BAUD_XTAL_DIV2 BIT(27) #define AML_UART_PORT_NUM 12 #define AML_UART_PORT_OFFSET 6 @@ -80,6 +81,10 @@ static struct uart_driver meson_uart_driver; static struct uart_port *meson_ports[AML_UART_PORT_NUM]; +struct meson_uart_data { + bool has_xtal_div2; +}; + static void meson_uart_set_mctrl(struct uart_port *port, unsigned int mctrl) { } @@ -293,13 +298,20 @@ static int meson_uart_startup(struct uart_port *port) static void meson_uart_change_speed(struct uart_port *port, unsigned long baud) { - u32 val; + const struct meson_uart_data *private_data = port->private_data; + u32 val = 0; while (!meson_uart_tx_empty(port)) cpu_relax(); if (port->uartclk == 24000000) { - val = DIV_ROUND_CLOSEST(port->uartclk / 3, baud) - 1; + unsigned int xtal_div = 3; + + if (private_data && private_data->has_xtal_div2) { + xtal_div = 2; + val |= AML_UART_BAUD_XTAL_DIV2; + } + val |= DIV_ROUND_CLOSEST(port->uartclk / xtal_div, baud) - 1; val |= AML_UART_BAUD_XTAL; } else { val = DIV_ROUND_CLOSEST(port->uartclk / 4, baud) - 1; @@ -749,6 +761,7 @@ static int meson_uart_probe(struct platform_device *pdev) port->x_char = 0; port->ops = &meson_uart_ops; port->fifosize = fifosize; + port->private_data = (void *)device_get_match_data(&pdev->dev); meson_ports[pdev->id] = port; platform_set_drvdata(pdev, port);