From patchwork Mon Jan 25 13:48:16 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johan Hovold X-Patchwork-Id: 371111 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DC289C43381 for ; Tue, 26 Jan 2021 19:32:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B83932311D for ; Tue, 26 Jan 2021 19:32:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388363AbhAZFm5 (ORCPT ); Tue, 26 Jan 2021 00:42:57 -0500 Received: from mail.kernel.org ([198.145.29.99]:49192 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729103AbhAYNvF (ORCPT ); Mon, 25 Jan 2021 08:51:05 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 089F222C9E; Mon, 25 Jan 2021 13:48:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1611582505; bh=8xzLVqBc4Jci34US4grEu+cGJ0o9R2i13nNACkFy6Uw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dh8ErcIB19k7yiaBeige7PIdnVy8VVUvNQxYDjOyJzpN4pdb0F4CWI0s6Op2DTorV +Yo/siyb/mg3+EGN7gli+8GQcpPS1FPIPS0MGgkZeP7e3fQx8rFV+HsZWDQD3vQlAt 7bpTfksWKytTqSK1lGrO8R2cBCv3FPIwoVWRYINoFWqCHDm6fZzfkFM9Ay0DMgmmhq oJJenFniHGbOymYupI7Qn3frFY1BQc1SKu5eq2kinr4F7+2rf7Ydq+c3/UxLz1PuF3 yvRLS22Auf6i7ivEfE66f5tUIniio5UnCb4MYbqr6CKdSvPCM5WcB2jLxfvClVwcm8 rNSG6O6Lg4tgQ== Received: from johan by xi.lan with local (Exim 4.93.0.4) (envelope-from ) id 1l42EM-00034c-1a; Mon, 25 Jan 2021 14:48:34 +0100 From: Johan Hovold To: linux-usb@vger.kernel.org Cc: Pho Tran , linux-kernel@vger.kernel.org, Johan Hovold Subject: [PATCH 6/7] USB: serial: cp210x: fix RTS handling Date: Mon, 25 Jan 2021 14:48:16 +0100 Message-Id: <20210125134817.11749-7-johan@kernel.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210125134817.11749-1-johan@kernel.org> References: <20210125134817.11749-1-johan@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Clearing TIOCM_RTS should always deassert RTS and setting the same bit should enable auto-RTS if hardware flow control is enabled. This allows user space to throttle input directly at the source also when hardware-assisted flow control is enabled and makes dtr_rts() always deassert both lines during close (when HUPCL is set). Signed-off-by: Johan Hovold --- drivers/usb/serial/cp210x.c | 47 +++++++++++++++++++++++++++++++------ 1 file changed, 40 insertions(+), 7 deletions(-) diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c index 4ba3fb096bf1..f00b736f3cd3 100644 --- a/drivers/usb/serial/cp210x.c +++ b/drivers/usb/serial/cp210x.c @@ -1166,7 +1166,10 @@ static void cp210x_set_flow_control(struct tty_struct *tty, if (C_CRTSCTS(tty)) { ctl_hs |= CP210X_SERIAL_CTS_HANDSHAKE; flow_repl &= ~CP210X_SERIAL_RTS_MASK; - flow_repl |= CP210X_SERIAL_RTS_FLOW_CTL; + if (port_priv->rts) + flow_repl |= CP210X_SERIAL_RTS_FLOW_CTL; + else + flow_repl |= CP210X_SERIAL_RTS_INACTIVE; port_priv->crtscts = true; } else { ctl_hs &= ~CP210X_SERIAL_CTS_HANDSHAKE; @@ -1286,6 +1289,8 @@ static int cp210x_tiocmset_port(struct usb_serial_port *port, unsigned int set, unsigned int clear) { struct cp210x_port_private *port_priv = usb_get_serial_port_data(port); + struct cp210x_flow_ctl flow_ctl; + u32 ctl_hs, flow_repl; u16 control = 0; int ret; @@ -1313,16 +1318,44 @@ static int cp210x_tiocmset_port(struct usb_serial_port *port, } /* - * SET_MHS cannot be used to control RTS when auto-RTS is enabled. - * Note that RTS is still deasserted when disabling the UART on close. + * Use SET_FLOW to set DTR and enable/disable auto-RTS when hardware + * flow control is enabled. */ - if (port_priv->crtscts) - control &= ~CONTROL_WRITE_RTS; + if (port_priv->crtscts && control & CONTROL_WRITE_RTS) { + ret = cp210x_read_reg_block(port, CP210X_GET_FLOW, &flow_ctl, + sizeof(flow_ctl)); + if (ret) + goto out_unlock; - dev_dbg(&port->dev, "%s - control = 0x%04x\n", __func__, control); + ctl_hs = le32_to_cpu(flow_ctl.ulControlHandshake); + flow_repl = le32_to_cpu(flow_ctl.ulFlowReplace); - ret = cp210x_write_u16_reg(port, CP210X_SET_MHS, control); + ctl_hs &= ~CP210X_SERIAL_DTR_MASK; + if (port_priv->dtr) + ctl_hs |= CP210X_SERIAL_DTR_ACTIVE; + else + ctl_hs |= CP210X_SERIAL_DTR_INACTIVE; + flow_repl &= ~CP210X_SERIAL_RTS_MASK; + if (port_priv->rts) + flow_repl |= CP210X_SERIAL_RTS_FLOW_CTL; + else + flow_repl |= CP210X_SERIAL_RTS_INACTIVE; + + flow_ctl.ulControlHandshake = cpu_to_le32(ctl_hs); + flow_ctl.ulFlowReplace = cpu_to_le32(flow_repl); + + dev_dbg(&port->dev, "%s - ctrl = 0x%02x, flow = 0x%02x\n", + __func__, ctl_hs, flow_repl); + + ret = cp210x_write_reg_block(port, CP210X_SET_FLOW, &flow_ctl, + sizeof(flow_ctl)); + } else { + dev_dbg(&port->dev, "%s - control = 0x%04x\n", __func__, control); + + ret = cp210x_write_u16_reg(port, CP210X_SET_MHS, control); + } +out_unlock: mutex_unlock(&port_priv->mutex); return ret;