From patchwork Fri Apr 29 20:40:18 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Maciej W. Rozycki" X-Patchwork-Id: 12832805 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 D5183C433F5 for ; Fri, 29 Apr 2022 20:56:28 +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:Message-ID: In-Reply-To:Subject:cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ff++pMqZV0mWBCePLGLETcsB3afrlpUcO/AC7M9rXO8=; b=QKRcCz6xX6XanD Cf3s1X6XXuzjT3JaN+zvE1LrLbSmOuGbuIu/Xhj1D76gl8+WhN/aOO7EwHMhxJovpRg+7B4ypDjWq edNBvvfQMCey9gtoYaDnz6DODAb6uBkPUptZor0pWp4UN/F8ibSh/CiAD8MnEZT9DOR5lZcTnA8Tj KWN1ZZ0/j7nLlHUh5xBYXol6AUzBedIe1y82rYqKrTQtfi2anG70puEzrU9x23wvBkI8/w0ZfYO1P V91j+dgdQjKU6FxD/bD874ya9gktmHuXgKrxvtWIzEryAhgdE9D/blqf3tIPvH3et4EK3MgZw9dNM rNETvw5SkZ8fC/LLzpnQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nkXez-00CdzN-G6; Fri, 29 Apr 2022 20:56:17 +0000 Received: from angie.orcam.me.uk ([2001:4190:8020::34]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nkXPZ-00CYVQ-D6 for linux-riscv@lists.infradead.org; Fri, 29 Apr 2022 20:40:23 +0000 Received: by angie.orcam.me.uk (Postfix, from userid 500) id A56B192009D; Fri, 29 Apr 2022 22:40:18 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by angie.orcam.me.uk (Postfix) with ESMTP id 9F1A892009B; Fri, 29 Apr 2022 21:40:18 +0100 (BST) Date: Fri, 29 Apr 2022 21:40:18 +0100 (BST) From: "Maciej W. Rozycki" To: Greg Kroah-Hartman , Jiri Slaby , Palmer Dabbelt , Paul Walmsley cc: Damien Le Moal , linux-serial@vger.kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/2] serial: sifive: Report actual baud base rather than fixed 115200 In-Reply-To: Message-ID: References: User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220429_134021_688328_278AE634 X-CRM114-Status: GOOD ( 12.87 ) X-BeenThere: linux-riscv@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-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org The base baud value reported is supposed to be the highest baud rate that can be set for a serial port. The SiFive FU740-C000 SOC's on-chip UART supports baud rates of up to 1/16 of the input clock rate, which is the bus clock `tlclk'[1], often at 130MHz in the case of the HiFive Unmatched board. However the sifive UART driver reports a fixed value of 115200 instead: 10010000.serial: ttySIF0 at MMIO 0x10010000 (irq = 1, base_baud = 115200) is a SiFive UART v0 10011000.serial: ttySIF1 at MMIO 0x10011000 (irq = 2, base_baud = 115200) is a SiFive UART v0 even though we already support setting higher baud rates, e.g.: $ tty /dev/ttySIF1 $ stty speed 230400 The baud base value is computed by the serial core by dividing the UART clock recorded in `struct uart_port' by 16, which is also the minimum value of the clock divider supported, so correct the baud base value reported by setting the UART clock recorded to the input clock rate rather than 115200: 10010000.serial: ttySIF0 at MMIO 0x10010000 (irq = 1, base_baud = 8125000) is a SiFive UART v0 10011000.serial: ttySIF1 at MMIO 0x10011000 (irq = 2, base_baud = 8125000) is a SiFive UART v0 References: [1] "SiFive FU740-C000 Manual", v1p3, SiFive, Inc., August 13, 2021, Section 16.9 "Baud Rate Divisor Register (div)", pp.143-144 Signed-off-by: Maciej W. Rozycki Fixes: 1f1496a923b6 ("riscv: Fix sifive serial driver") --- drivers/tty/serial/sifive.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) linux-serial-sifive-base-baud.diff Index: linux-macro/drivers/tty/serial/sifive.c =================================================================== --- linux-macro.orig/drivers/tty/serial/sifive.c +++ linux-macro/drivers/tty/serial/sifive.c @@ -998,7 +998,7 @@ static int sifive_serial_probe(struct pl /* Set up clock divider */ ssp->clkin_rate = clk_get_rate(ssp->clk); ssp->baud_rate = SIFIVE_DEFAULT_BAUD_RATE; - ssp->port.uartclk = ssp->baud_rate * 16; + ssp->port.uartclk = ssp->clkin_rate; __ssp_update_div(ssp); platform_set_drvdata(pdev, ssp);