From patchwork Fri Oct 16 02:24:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sheng Long Wang X-Patchwork-Id: 297291 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=-12.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, 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 7EE12C43457 for ; Fri, 16 Oct 2020 02:25:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2D27220878 for ; Fri, 16 Oct 2020 02:25:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="V7PPrerE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2393725AbgJPCZd (ORCPT ); Thu, 15 Oct 2020 22:25:33 -0400 Received: from m12-18.163.com ([220.181.12.18]:50257 "EHLO m12-18.163.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2393722AbgJPCZc (ORCPT ); Thu, 15 Oct 2020 22:25:32 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Subject:Date:Message-Id; bh=ACNOSwLeo9rkV9/i8o FvJHx5NnDcSRXn99lMNbUKNpY=; b=V7PPrerEHRbOEpN/wkBCk7q2QaBCD+3jiF WP4dJWyilew9wDH5NhFP6khOLyCCpvh8931Q0xvlbPIlwIe9VEaTfih2e5dag1/k h0Uh+kZeRew0bh+uuY1aCR6UoGaLt0EGxTAq/rnIR+FA+XItYRCPlNgUmwI+N9ho Is3yW8/n8= Received: from localhost.localdomain (unknown [118.113.10.145]) by smtp14 (Coremail) with SMTP id EsCowACXGsFrBIlfFosDTg--.401S4; Fri, 16 Oct 2020 10:24:44 +0800 (CST) From: Sheng Long Wang To: johan@kernel.org, gregkh@linuxfoundation.org Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, lkp@intel.com, Wang Sheng Long Subject: [PATCH v6] usb-serial:cp210x: add support to software flow control Date: Fri, 16 Oct 2020 10:24:28 +0800 Message-Id: <20201016022428.9671-1-china_shenglong@163.com> X-Mailer: git-send-email 2.17.1 X-CM-TRANSID: EsCowACXGsFrBIlfFosDTg--.401S4 X-Coremail-Antispam: 1Uf129KBjvJXoW3JF45Jw18Jr45GF1rXr48Crg_yoWxWw4UpF 15trWFyFWDZa1YgF4FyF4UCr98ua1SqFyqyFyak39IyF43Gw4fKF1xKa4Yyr1UAr48Jry5 trnIyFyDuF1UArJanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07jfvtAUUUUU= X-Originating-IP: [118.113.10.145] X-CM-SenderInfo: xfkl0tpbvkv0xjor0wi6rwjhhfrp/1tbiEwy-slXlywG7rgAAs9 Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org From: Wang Sheng Long When data is transmitted between two serial ports, the phenomenon of data loss often occurs. The two kinds of flow control commonly used in serial communication are hardware flow control and software flow control. In serial communication, If you only use RX/TX/GND Pins, you can't do hardware flow. So we often used software flow control and prevent data loss. The user sets the software flow control through the application program, and the application program sets the software flow control mode for the serial port chip through the driver. For the cp210 serial port chip, its driver lacks the software flow control setting code, so the user cannot set the software flow control function through the application program. This adds the missing software flow control. Signed-off-by: Wang Sheng Long Changes in v3: - fixed code style, It mainly adjusts the code style acccording to kernel specification. Changes in v4: - It mainly adjusts the patch based on the last usb-next branch of the usb-serial. Changes in v5: - Fixes: * According to the cp210x specification, use usb_control_msg() requesttype 'REQTYPE_DEVICE_TO_HOST' is modified to 'REQTYPE_INTERFACE_TO_HOST' in cp210x_get_chars(). * If modify IXOFF/IXON has been changed, we can call set software flow control code. * If the setting software flow control wrong, do not continue processing proceed with updating software flow control. Changes in v6: - Fix 'result' variable not uninitialized warning in cp210x_set_termios(). --- drivers/usb/serial/cp210x.c | 128 ++++++++++++++++++++++++++++++++++-- 1 file changed, 123 insertions(+), 5 deletions(-) diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c index d0c05aa8a0d6..2d5e31282599 100644 --- a/drivers/usb/serial/cp210x.c +++ b/drivers/usb/serial/cp210x.c @@ -412,6 +412,15 @@ struct cp210x_comm_status { u8 bReserved; } __packed; +struct cp210x_special_chars { + u8 bEofChar; + u8 bErrorChar; + u8 bBreakChar; + u8 bEventChar; + u8 bXonChar; + u8 bXoffChar; +}; + /* * CP210X_PURGE - 16 bits passed in wValue of USB request. * SiLabs app note AN571 gives a strange description of the 4 bits: @@ -675,6 +684,70 @@ static int cp210x_read_vendor_block(struct usb_serial *serial, u8 type, u16 val, return result; } +static int cp210x_get_chars(struct usb_serial_port *port, void *buf) +{ + struct usb_serial *serial = port->serial; + struct cp210x_port_private *port_priv = usb_get_serial_port_data(port); + struct cp210x_special_chars *special_chars; + void *dmabuf; + int result; + + dmabuf = kmemdup(buf, sizeof(*special_chars), GFP_KERNEL); + if (!dmabuf) + return -ENOMEM; + + result = usb_control_msg(serial->dev, + usb_rcvctrlpipe(serial->dev, 0), + CP210X_GET_CHARS, REQTYPE_INTERFACE_TO_HOST, 0, + port_priv->bInterfaceNumber, + dmabuf, sizeof(*special_chars), + USB_CTRL_GET_TIMEOUT); + + if (result == sizeof(*special_chars)) { + memcpy(buf, dmabuf, sizeof(*special_chars)); + result = 0; + } else { + dev_err(&port->dev, "failed to get special chars: %d\n", result); + if (result >= 0) + result = -EIO; + } + + kfree(dmabuf); + + return result; +} + +static int cp210x_set_chars(struct usb_serial_port *port, void *buf) +{ + struct usb_serial *serial = port->serial; + struct cp210x_port_private *port_priv = usb_get_serial_port_data(port); + struct cp210x_special_chars *special_chars; + void *dmabuf; + int result; + + dmabuf = kmemdup(buf, sizeof(*special_chars), GFP_KERNEL); + if (!dmabuf) + return -ENOMEM; + + result = usb_control_msg(serial->dev, + usb_sndctrlpipe(serial->dev, 0), + CP210X_SET_CHARS, REQTYPE_HOST_TO_INTERFACE, 0, + port_priv->bInterfaceNumber, + dmabuf, sizeof(*special_chars), USB_CTRL_SET_TIMEOUT); + + if (result == sizeof(*special_chars)) { + result = 0; + } else { + dev_err(&port->dev, "failed to set special chars: %d\n", result); + if (result >= 0) + result = -EIO; + } + + kfree(dmabuf); + + return result; +} + /* * Writes any 16-bit CP210X_ register (req) whose value is passed * entirely in the wValue field of the USB request. @@ -1356,11 +1429,18 @@ static void cp210x_set_termios(struct tty_struct *tty, struct usb_serial_port *port, struct ktermios *old_termios) { struct device *dev = &port->dev; - unsigned int cflag, old_cflag; + unsigned int cflag, old_cflag, iflag, old_iflag; + struct cp210x_special_chars special_chars; + struct cp210x_flow_ctl flow_ctl; u16 bits; + int result = 0; + u32 ctl_hs; + u32 flow_repl; cflag = tty->termios.c_cflag; + iflag = tty->termios.c_iflag; old_cflag = old_termios->c_cflag; + old_iflag = old_termios->c_iflag; if (tty->termios.c_ospeed != old_termios->c_ospeed) cp210x_change_speed(tty, port, old_termios); @@ -1434,10 +1514,6 @@ static void cp210x_set_termios(struct tty_struct *tty, } if ((cflag & CRTSCTS) != (old_cflag & CRTSCTS)) { - struct cp210x_flow_ctl flow_ctl; - u32 ctl_hs; - u32 flow_repl; - cp210x_read_reg_block(port, CP210X_GET_FLOW, &flow_ctl, sizeof(flow_ctl)); ctl_hs = le32_to_cpu(flow_ctl.ulControlHandshake); @@ -1474,6 +1550,48 @@ static void cp210x_set_termios(struct tty_struct *tty, sizeof(flow_ctl)); } + if (((iflag & IXOFF) != (old_iflag & IXOFF)) || + ((iflag & IXON) != (old_iflag & IXON))) { + result = cp210x_get_chars(port, &special_chars); + if (result < 0) + goto out; + + special_chars.bXonChar = START_CHAR(tty); + special_chars.bXoffChar = STOP_CHAR(tty); + + result = cp210x_set_chars(port, &special_chars); + if (result < 0) + goto out; + + result = cp210x_read_reg_block(port, + CP210X_GET_FLOW, + &flow_ctl, + sizeof(flow_ctl)); + if (result < 0) + goto out; + + flow_repl = le32_to_cpu(flow_ctl.ulFlowReplace); + + if (iflag & IXOFF) + flow_repl |= CP210X_SERIAL_AUTO_RECEIVE; + else + flow_repl &= ~CP210X_SERIAL_AUTO_RECEIVE; + + if (iflag & IXON) + flow_repl |= CP210X_SERIAL_AUTO_TRANSMIT; + else + flow_repl &= ~CP210X_SERIAL_AUTO_TRANSMIT; + + flow_ctl.ulFlowReplace = cpu_to_le32(flow_repl); + result = cp210x_write_reg_block(port, + CP210X_SET_FLOW, + &flow_ctl, + sizeof(flow_ctl)); + } +out: + if (result < 0) + dev_err(dev, "failed to set software flow control: %d\n", result); + /* * Enable event-insertion mode only if input parity checking is * enabled for now.