From patchwork Fri Dec 27 22:45:20 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Ogness X-Patchwork-Id: 854157 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 61FCF157E82; Fri, 27 Dec 2024 22:45:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735339536; cv=none; b=XCCzbdEuQdo7z35kzdVRf8uyvH67Xo4D1PnBdI0JkOdQC9MwmZpuDxCnUIT5cG8wLFjce0rhUEnneSjeeP20zTXlaw7YKE1Pcg1kPYUtFSZUodozF2h7NnbUEnMP60ry1YLBcJNNCZELgI/rp0EML2TSMr4lVizgjiJgeFD1REo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735339536; c=relaxed/simple; bh=BgDAW/j4qyu0YBOstKGTm7JxD7KvCBzhabJC69kgChw=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=AsPd9KerWIJ2ih9t9GW0WXc8lAsfYv97WV6ylbel655i7HdQ/Hmv3fUiDgv6e6gzMkYUqdMxp6f7KB0zmfz8fTeVcI5tA3N6BYRu89IHfUAAlTCKyV25CRhmC/1ndfeIxTYvGYuIxaofmZf3dZ1wNDMrrj2UePPqStx61j6tDio= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=YGbNTbzB; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=oWsyHpU7; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="YGbNTbzB"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="oWsyHpU7" From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1735339526; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=L823infgxoPboFK1hsbz+0QBq7B/x6XIBXkE7NZh1f8=; b=YGbNTbzBTy66oo55AeF5o775D61asoChdnm8Biwh8koJlPtqF6aee12UoeuOc1Bl3BET7K rl+TE1nVICwyB//mgl11pGUdHNpt4Q+uCHYvVXWN7tTkLpxfOOXpX85KZk4DKX8r7YbWfx hSsEDYz23eZEVKy6Dmvuiwej7PxxLf5Pbs0lHaipHjX7jOhm79QgC8hjBtDqQz7WAYY92o fvgZyQQANt7AWGgRXJbbw8NJo5fgQV2N69GzN3ox0uBUgbWV0FTzghta9cZV5urbNECuhQ dYmtLF5NWFoRX51JHmcMPRB+lTQINVKAFts3//9viw/rzs4ijbgZeH1wcAKkmA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1735339526; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=L823infgxoPboFK1hsbz+0QBq7B/x6XIBXkE7NZh1f8=; b=oWsyHpU7fUTd2Uyl0zR6i6Y1C96s5dNNwcaZBG/PLK2L4Wz7IUPWOsAAeYdvT9KDnhcfLM Zh93w+x+ytHgv0BQ== To: Greg Kroah-Hartman Cc: Jiri Slaby , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , Esben Haabendal , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Florian Fainelli , Ray Jui , Scott Branden , Broadcom internal kernel review list , Andy Shevchenko , Arnd Bergmann , Sunil V L , Matt Turner , Stefan Wahren , =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= , Kevin Hilman , Markus Schneider-Pargmann , Udit Kumar , Griffin Kroah-Hartman , Niklas Schnelle , Serge Semin , linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH tty-next v4 4/6] serial: 8250: Provide flag for IER toggling for RS485 Date: Fri, 27 Dec 2024 23:51:20 +0106 Message-Id: <20241227224523.28131-5-john.ogness@linutronix.de> In-Reply-To: <20241227224523.28131-1-john.ogness@linutronix.de> References: <20241227224523.28131-1-john.ogness@linutronix.de> Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 For RS485 mode, if SER_RS485_RX_DURING_TX is not available, the console ->write() callback needs to enable/disable Tx. It does this by calling the ->rs485_start_tx() and ->rs485_stop_tx() callbacks. However, some of these callbacks also disable/enable interrupts and makes power management calls. This causes 2 problems for console writing: 1. A console write can occur in contexts that are illegal for pm_runtime_*(). It is not even necessary for console writing to use pm_runtime_*() because a console already does this in serial8250_console_setup() and serial8250_console_exit(). 2. The console ->write() callback already handles disabling/enabling the interrupts by properly restoring the previous IER value. Add an argument @toggle_ier to the ->rs485_start_tx() and ->rs485_stop_tx() callbacks to specify if they may disable/enable receive interrupts while using pm_runtime_*(). Console writing will not allow the toggling. For all call sites other than console writing there is no functional change. Signed-off-by: John Ogness --- drivers/tty/serial/8250/8250.h | 4 ++-- drivers/tty/serial/8250/8250_bcm2835aux.c | 4 ++-- drivers/tty/serial/8250/8250_omap.c | 2 +- drivers/tty/serial/8250/8250_port.c | 26 +++++++++++++---------- include/linux/serial_8250.h | 4 ++-- 5 files changed, 22 insertions(+), 18 deletions(-) diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h index e5310c65cf52..11e05aa014e5 100644 --- a/drivers/tty/serial/8250/8250.h +++ b/drivers/tty/serial/8250/8250.h @@ -231,8 +231,8 @@ void serial8250_rpm_put_tx(struct uart_8250_port *p); int serial8250_em485_config(struct uart_port *port, struct ktermios *termios, struct serial_rs485 *rs485); -void serial8250_em485_start_tx(struct uart_8250_port *p); -void serial8250_em485_stop_tx(struct uart_8250_port *p); +void serial8250_em485_start_tx(struct uart_8250_port *p, bool toggle_ier); +void serial8250_em485_stop_tx(struct uart_8250_port *p, bool toggle_ier); void serial8250_em485_destroy(struct uart_8250_port *p); extern struct serial_rs485 serial8250_em485_supported; diff --git a/drivers/tty/serial/8250/8250_bcm2835aux.c b/drivers/tty/serial/8250/8250_bcm2835aux.c index fdb53b54e99e..0609582a62f7 100644 --- a/drivers/tty/serial/8250/8250_bcm2835aux.c +++ b/drivers/tty/serial/8250/8250_bcm2835aux.c @@ -46,7 +46,7 @@ struct bcm2835aux_data { u32 cntl; }; -static void bcm2835aux_rs485_start_tx(struct uart_8250_port *up) +static void bcm2835aux_rs485_start_tx(struct uart_8250_port *up, bool toggle_ier) { if (!(up->port.rs485.flags & SER_RS485_RX_DURING_TX)) { struct bcm2835aux_data *data = dev_get_drvdata(up->port.dev); @@ -65,7 +65,7 @@ static void bcm2835aux_rs485_start_tx(struct uart_8250_port *up) serial8250_out_MCR(up, UART_MCR_RTS); } -static void bcm2835aux_rs485_stop_tx(struct uart_8250_port *up) +static void bcm2835aux_rs485_stop_tx(struct uart_8250_port *up, bool toggle_ier) { if (up->port.rs485.flags & SER_RS485_RTS_AFTER_SEND) serial8250_out_MCR(up, 0); diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c index 42b4aa56b902..c2b75e3f106d 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -365,7 +365,7 @@ static void omap8250_restore_regs(struct uart_8250_port *up) if (up->port.rs485.flags & SER_RS485_ENABLED && up->port.rs485_config == serial8250_em485_config) - serial8250_em485_stop_tx(up); + serial8250_em485_stop_tx(up, true); } /* diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 812f003c252d..e38271f477d1 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -578,7 +578,7 @@ static int serial8250_em485_init(struct uart_8250_port *p) deassert_rts: if (p->em485->tx_stopped) - p->rs485_stop_tx(p); + p->rs485_stop_tx(p, true); return 0; } @@ -1398,10 +1398,11 @@ static void serial8250_stop_rx(struct uart_port *port) /** * serial8250_em485_stop_tx() - generic ->rs485_stop_tx() callback * @p: uart 8250 port + * @toggle_ier: true to allow enabling receive interrupts * * Generic callback usable by 8250 uart drivers to stop rs485 transmission. */ -void serial8250_em485_stop_tx(struct uart_8250_port *p) +void serial8250_em485_stop_tx(struct uart_8250_port *p, bool toggle_ier) { unsigned char mcr = serial8250_in_MCR(p); @@ -1422,8 +1423,10 @@ void serial8250_em485_stop_tx(struct uart_8250_port *p) if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX)) { serial8250_clear_and_reinit_fifos(p); - p->ier |= UART_IER_RLSI | UART_IER_RDI; - serial_port_out(&p->port, UART_IER, p->ier); + if (toggle_ier) { + p->ier |= UART_IER_RLSI | UART_IER_RDI; + serial_port_out(&p->port, UART_IER, p->ier); + } } } EXPORT_SYMBOL_GPL(serial8250_em485_stop_tx); @@ -1438,7 +1441,7 @@ static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t) serial8250_rpm_get(p); uart_port_lock_irqsave(&p->port, &flags); if (em485->active_timer == &em485->stop_tx_timer) { - p->rs485_stop_tx(p); + p->rs485_stop_tx(p, true); em485->active_timer = NULL; em485->tx_stopped = true; } @@ -1470,7 +1473,7 @@ static void __stop_tx_rs485(struct uart_8250_port *p, u64 stop_delay) em485->active_timer = &em485->stop_tx_timer; hrtimer_start(&em485->stop_tx_timer, ns_to_ktime(stop_delay), HRTIMER_MODE_REL); } else { - p->rs485_stop_tx(p); + p->rs485_stop_tx(p, true); em485->active_timer = NULL; em485->tx_stopped = true; } @@ -1559,6 +1562,7 @@ static inline void __start_tx(struct uart_port *port) /** * serial8250_em485_start_tx() - generic ->rs485_start_tx() callback * @up: uart 8250 port + * @toggle_ier: true to allow disabling receive interrupts * * Generic callback usable by 8250 uart drivers to start rs485 transmission. * Assumes that setting the RTS bit in the MCR register means RTS is high. @@ -1566,11 +1570,11 @@ static inline void __start_tx(struct uart_port *port) * stoppable by disabling the UART_IER_RDI interrupt. (Some chips set the * UART_LSR_DR bit even when UART_IER_RDI is disabled, foiling this approach.) */ -void serial8250_em485_start_tx(struct uart_8250_port *up) +void serial8250_em485_start_tx(struct uart_8250_port *up, bool toggle_ier) { unsigned char mcr = serial8250_in_MCR(up); - if (!(up->port.rs485.flags & SER_RS485_RX_DURING_TX)) + if (!(up->port.rs485.flags & SER_RS485_RX_DURING_TX) && toggle_ier) serial8250_stop_rx(&up->port); if (up->port.rs485.flags & SER_RS485_RTS_ON_SEND) @@ -1604,7 +1608,7 @@ static bool start_tx_rs485(struct uart_port *port) if (em485->tx_stopped) { em485->tx_stopped = false; - up->rs485_start_tx(up); + up->rs485_start_tx(up, true); if (up->port.rs485.delay_rts_before_send > 0) { em485->active_timer = &em485->start_tx_timer; @@ -3423,7 +3427,7 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s, if (em485) { if (em485->tx_stopped) - up->rs485_start_tx(up); + up->rs485_start_tx(up, false); mdelay(port->rs485.delay_rts_before_send); } @@ -3461,7 +3465,7 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s, if (em485) { mdelay(port->rs485.delay_rts_after_send); if (em485->tx_stopped) - up->rs485_stop_tx(up); + up->rs485_stop_tx(up, false); } serial_port_out(port, UART_IER, ier); diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h index e0717c8393d7..144de7a7948d 100644 --- a/include/linux/serial_8250.h +++ b/include/linux/serial_8250.h @@ -161,8 +161,8 @@ struct uart_8250_port { void (*dl_write)(struct uart_8250_port *up, u32 value); struct uart_8250_em485 *em485; - void (*rs485_start_tx)(struct uart_8250_port *); - void (*rs485_stop_tx)(struct uart_8250_port *); + void (*rs485_start_tx)(struct uart_8250_port *up, bool toggle_ier); + void (*rs485_stop_tx)(struct uart_8250_port *up, bool toggle_ier); /* Serial port overrun backoff */ struct delayed_work overrun_backoff;