From mboxrd@z Thu Jan 1 00:00:00 1970 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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham 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 B35F4C10DCE for ; Wed, 18 Mar 2020 14:27:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 94A5A20773 for ; Wed, 18 Mar 2020 14:27:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727095AbgCRO1P (ORCPT ); Wed, 18 Mar 2020 10:27:15 -0400 Received: from gloria.sntech.de ([185.11.138.130]:37358 "EHLO gloria.sntech.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726911AbgCRO1A (ORCPT ); Wed, 18 Mar 2020 10:27:00 -0400 Received: from [94.134.91.63] (helo=phil.fritz.box) by gloria.sntech.de with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.89) (envelope-from ) id 1jEZeo-0004YX-AJ; Wed, 18 Mar 2020 15:26:54 +0100 From: Heiko Stuebner To: gregkh@linuxfoundation.org Cc: jslaby@suse.com, andriy.shevchenko@linux.intel.com, matwey.kornilov@gmail.com, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, heiko@sntech.de, Giulio Benetti , Heiko Stuebner Subject: [PATCH 3/7] serial: 8250: Handle case port doesn't have TEMT interrupt using em485. Date: Wed, 18 Mar 2020 15:26:36 +0100 Message-Id: <20200318142640.982763-4-heiko@sntech.de> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200318142640.982763-1-heiko@sntech.de> References: <20200318142640.982763-1-heiko@sntech.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org From: Giulio Benetti Some 8250 ports only have TEMT interrupt, so current implementation can't work for ports without it. The only chance to make it work is to loop-read on LSR register. With NO TEMT interrupt check if both TEMT and THRE are set looping on LSR register. Signed-off-by: Giulio Benetti Signed-off-by: Heiko Stuebner --- drivers/tty/serial/8250/8250.h | 2 +- drivers/tty/serial/8250/8250_of.c | 2 +- drivers/tty/serial/8250/8250_omap.c | 2 +- drivers/tty/serial/8250/8250_port.c | 30 +++++++++++++++++++++-------- include/linux/serial_8250.h | 1 + 5 files changed, 26 insertions(+), 11 deletions(-) diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h index 50a4c174410d..9e049d2a039e 100644 --- a/drivers/tty/serial/8250/8250.h +++ b/drivers/tty/serial/8250/8250.h @@ -190,7 +190,7 @@ void serial8250_rpm_put(struct uart_8250_port *p); void serial8250_rpm_get_tx(struct uart_8250_port *p); void serial8250_rpm_put_tx(struct uart_8250_port *p); -int serial8250_em485_init(struct uart_8250_port *p); +int serial8250_em485_init(struct uart_8250_port *p, bool has_temt_isr); void serial8250_em485_destroy(struct uart_8250_port *p); /* MCR <-> TIOCM conversion */ diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c index 92fbf46ce3bd..c77ab44a5468 100644 --- a/drivers/tty/serial/8250/8250_of.c +++ b/drivers/tty/serial/8250/8250_of.c @@ -64,7 +64,7 @@ static int of_8250_rs485_config(struct uart_port *port, * are idempotent */ if (rs485->flags & SER_RS485_ENABLED) { - int ret = serial8250_em485_init(up); + int ret = serial8250_em485_init(up, true); if (ret) { rs485->flags &= ~SER_RS485_ENABLED; diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c index 836e736ae188..241322900298 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -734,7 +734,7 @@ static int omap_8250_rs485_config(struct uart_port *port, * are idempotent */ if (rs485->flags & SER_RS485_ENABLED) { - int ret = serial8250_em485_init(up); + int ret = serial8250_em485_init(up, true); if (ret) { rs485->flags &= ~SER_RS485_ENABLED; diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 67aa3a2a9afa..3d1d8490bc42 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -605,15 +605,17 @@ EXPORT_SYMBOL_GPL(serial8250_rpm_put); /** * serial8250_em485_init() - put uart_8250_port into rs485 emulating * @p: uart_8250_port port instance + * @p: bool specify if 8250 port has TEMT interrupt or not * * The function is used to start rs485 software emulating on the * &struct uart_8250_port* @p. Namely, RTS is switched before/after * transmission. The function is idempotent, so it is safe to call it * multiple times. * - * The caller MUST enable interrupt on empty shift register before - * calling serial8250_em485_init(). This interrupt is not a part of - * 8250 standard, but implementation defined. + * If has_temt_isr is passed as true, the caller MUST enable interrupt + * on empty shift register before calling serial8250_em485_init(). + * This interrupt is not a part of 8250 standard, but implementation + * defined. * * The function is supposed to be called from .rs485_config callback * or from any other callback protected with p->port.lock spinlock. @@ -622,7 +624,7 @@ EXPORT_SYMBOL_GPL(serial8250_rpm_put); * * Return 0 - success, -errno - otherwise */ -int serial8250_em485_init(struct uart_8250_port *p) +int serial8250_em485_init(struct uart_8250_port *p, bool has_temt_isr) { if (p->em485) return 0; @@ -639,6 +641,7 @@ int serial8250_em485_init(struct uart_8250_port *p) p->em485->start_tx_timer.function = &serial8250_em485_handle_start_tx; p->em485->port = p; p->em485->active_timer = NULL; + p->em485->has_temt_isr = has_temt_isr; serial8250_em485_rts_after_send(p); return 0; @@ -1475,11 +1478,22 @@ static inline void __stop_tx(struct uart_8250_port *p) /* * To provide required timeing and allow FIFO transfer, * __stop_tx_rs485() must be called only when both FIFO and - * shift register are empty. It is for device driver to enable - * interrupt on TEMT. + * shift register are empty. If 8250 port supports it, + * it is for device driver to enable interrupt on TEMT. + * Otherwise must loop-read until TEMT and THRE flags are set. */ - if ((lsr & BOTH_EMPTY) != BOTH_EMPTY) - return; + if (em485->has_temt_isr) { + if ((lsr & BOTH_EMPTY) != BOTH_EMPTY) + return; + } else { + int val; + + if (serial_in_poll_timeout(p, UART_LSR, val, + (val & BOTH_EMPTY) != BOTH_EMPTY, + 100000) < 0) + pr_warn("%s: timeout waiting for fifos to empty\n", + p->port.name); + } em485->active_timer = NULL; diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h index bb2bc99388ca..c4b4469c272b 100644 --- a/include/linux/serial_8250.h +++ b/include/linux/serial_8250.h @@ -79,6 +79,7 @@ struct uart_8250_em485 { struct hrtimer start_tx_timer; /* "rs485 start tx" timer */ struct hrtimer stop_tx_timer; /* "rs485 stop tx" timer */ struct hrtimer *active_timer; /* pointer to active timer */ + bool has_temt_isr; /* variant has TEMT interrupt */ struct uart_8250_port *port; /* for hrtimer callbacks */ }; -- 2.24.1