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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B1E28C6FA8E for ; Thu, 2 Mar 2023 20:02:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229596AbjCBUCA (ORCPT ); Thu, 2 Mar 2023 15:02:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33474 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229560AbjCBUB4 (ORCPT ); Thu, 2 Mar 2023 15:01:56 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 79A0B580CF; Thu, 2 Mar 2023 12:01:18 -0800 (PST) From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1677787213; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=DoYVoXVZrCYkg08eCZi+GFBjouXoTRm7NbD5Lab3y1I=; b=VBIL4+Msso+bsBpBkRWgUCzcxeRp/G3msz+6YpJrTDuNdC6iezrN/x8tA0fYEyze716M/e Ra+bxRMisvYR8HtexQc1Sf69B0qG8jszsCddr+l+Gh8R7B1XuVa/ZxsMuE+fVQp1ulQ7xr rveb8Yf36aQCkI9jvfUqD9WR2U5qObgZj5162d3losRwGeiSmzuc0FfvAkLCEUCGI6saqp sbFvh7sDdlXfOqVuHZG0Hxq7amwBT+LGqKrAJyIF9v4+V1JoAjGDlxerkydG6VW96p+DJy aoE45PIkBISGYZQkDZPHyAeEGC5urD1+b4k7xL1iR1txma/eGahduqhk1DQx0Q== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1677787213; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=DoYVoXVZrCYkg08eCZi+GFBjouXoTRm7NbD5Lab3y1I=; b=TgHHbQF6uSL3sXilGT+WTi8RkER3+tScRX/N2/F3apPRIcJkA24h1B4cOQQd8Aim3txLrV nlMqE8sHjjgzxbBg== To: Petr Mladek Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, Jason Wessel , Daniel Thompson , Douglas Anderson , Aaron Tomlin , Luis Chamberlain , kgdb-bugreport@lists.sourceforge.net, Greg Kroah-Hartman , linux-fsdevel@vger.kernel.org, Andrew Morton , "Guilherme G. Piccoli" , David Gow , Tiezhu Yang , Daniel Vetter , tangmeng , "Paul E. McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Josh Triplett , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , rcu@vger.kernel.org Subject: [PATCH printk v1 00/18] serial: 8250: implement non-BKL console In-Reply-To: <20230302195618.156940-1-john.ogness@linutronix.de> References: <20230302195618.156940-1-john.ogness@linutronix.de> Date: Thu, 02 Mar 2023 21:04:50 +0106 Message-ID: <87wn3zsz5x.fsf@jogness.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org Implement the necessary callbacks to allow the 8250 console driver to perform as a non-BKL console. Remove the implementation for the legacy console callback (write) and add implementations for the non-BKL consoles (write_atomic, write_thread, port_lock) and add CON_NO_BKL to the initial flags. This is an all-in-one commit meant only for testing the new printk non-BKL infrastructure. It is not meant to be included mainline in this form. In particular, it includes mainline driver fixes that need to be submitted individually. Although non-BKL consoles can coexist with legacy consoles, you will only receive all the benefits of the non-BKL consoles, if this console driver is the only console. That means no netconsole, no tty1, no earlyprintk, no earlycon. Just the uart8250. For example: console=ttyS0,115200 Signed-off-by: John Ogness diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h index 287153d32536..d8da34bb9ae3 100644 --- a/drivers/tty/serial/8250/8250.h +++ b/drivers/tty/serial/8250/8250.h @@ -177,12 +177,154 @@ static inline void serial_dl_write(struct uart_8250_port *up, int value) up->dl_write(up, value); } +static inline bool serial8250_is_console(struct uart_port *port) +{ + return uart_console(port) && !hlist_unhashed_lockless(&port->cons->node); +} + +static inline void serial8250_init_wctxt(struct cons_write_context *wctxt, + struct console *cons) +{ + struct cons_context *ctxt = &ACCESS_PRIVATE(wctxt, ctxt); + + memset(wctxt, 0, sizeof(*wctxt)); + ctxt->console = cons; + ctxt->prio = CONS_PRIO_NORMAL; + /* Both require the port lock, so they cannot clobber each other. */ + ctxt->thread = 1; +} + +static inline void serial8250_console_acquire(struct cons_write_context *wctxt, + struct console *cons) +{ + serial8250_init_wctxt(wctxt, cons); + while (!console_try_acquire(wctxt)) { + cpu_relax(); + serial8250_init_wctxt(wctxt, cons); + } +} + +static inline void serial8250_enter_unsafe(struct uart_8250_port *up) +{ + struct uart_port *port = &up->port; + + lockdep_assert_held_once(&port->lock); + + for (;;) { + up->cookie = console_srcu_read_lock(); + + serial8250_console_acquire(&up->wctxt, port->cons); + + if (console_enter_unsafe(&up->wctxt)) + break; + + console_srcu_read_unlock(up->cookie); + cpu_relax(); + } +} + +static inline void serial8250_exit_unsafe(struct uart_8250_port *up) +{ + struct uart_port *port = &up->port; + + lockdep_assert_held_once(&port->lock); + + /* + * FIXME: The 8250 driver does not support hostile takeovers + * in the unsafe section. + */ + if (!WARN_ON_ONCE(!console_exit_unsafe(&up->wctxt))) + WARN_ON_ONCE(!console_release(&up->wctxt)); + + console_srcu_read_unlock(up->cookie); +} + +static inline int serial8250_in_IER(struct uart_8250_port *up) +{ + struct uart_port *port = &up->port; + bool is_console; + int ier; + + is_console = serial8250_is_console(port); + + if (is_console) + serial8250_enter_unsafe(up); + + ier = serial_in(up, UART_IER); + + if (is_console) + serial8250_exit_unsafe(up); + + return ier; +} + +static inline bool __serial8250_set_IER(struct uart_8250_port *up, + struct cons_write_context *wctxt, + int ier) +{ + if (wctxt && !console_can_proceed(wctxt)) + return false; + serial_out(up, UART_IER, ier); + return true; +} + +static inline void serial8250_set_IER(struct uart_8250_port *up, int ier) +{ + struct uart_port *port = &up->port; + bool is_console; + + is_console = serial8250_is_console(port); + + if (is_console) { + serial8250_enter_unsafe(up); + __serial8250_set_IER(up, &up->wctxt, ier); + serial8250_exit_unsafe(up); + } else { + __serial8250_set_IER(up, NULL, ier); + } +} + +static inline bool __serial8250_clear_IER(struct uart_8250_port *up, + struct cons_write_context *wctxt, + int *prior) +{ + unsigned int clearval = 0; + + if (up->capabilities & UART_CAP_UUE) + clearval = UART_IER_UUE; + + *prior = serial_in(up, UART_IER); + if (wctxt && !console_can_proceed(wctxt)) + return false; + serial_out(up, UART_IER, clearval); + return true; +} + +static inline int serial8250_clear_IER(struct uart_8250_port *up) +{ + struct uart_port *port = &up->port; + bool is_console; + int prior; + + is_console = serial8250_is_console(port); + + if (is_console) { + serial8250_enter_unsafe(up); + __serial8250_clear_IER(up, &up->wctxt, &prior); + serial8250_exit_unsafe(up); + } else { + __serial8250_clear_IER(up, NULL, &prior); + } + + return prior; +} + static inline bool serial8250_set_THRI(struct uart_8250_port *up) { if (up->ier & UART_IER_THRI) return false; up->ier |= UART_IER_THRI; - serial_out(up, UART_IER, up->ier); + serial8250_set_IER(up, up->ier); return true; } @@ -191,7 +333,7 @@ static inline bool serial8250_clear_THRI(struct uart_8250_port *up) if (!(up->ier & UART_IER_THRI)) return false; up->ier &= ~UART_IER_THRI; - serial_out(up, UART_IER, up->ier); + serial8250_set_IER(up, up->ier); return true; } diff --git a/drivers/tty/serial/8250/8250_aspeed_vuart.c b/drivers/tty/serial/8250/8250_aspeed_vuart.c index 9d2a7856784f..7cc6b527c088 100644 --- a/drivers/tty/serial/8250/8250_aspeed_vuart.c +++ b/drivers/tty/serial/8250/8250_aspeed_vuart.c @@ -278,7 +278,7 @@ static void __aspeed_vuart_set_throttle(struct uart_8250_port *up, up->ier &= ~irqs; if (!throttle) up->ier |= irqs; - serial_out(up, UART_IER, up->ier); + serial8250_set_IER(up, up->ier); } static void aspeed_vuart_set_throttle(struct uart_port *port, bool throttle) { diff --git a/drivers/tty/serial/8250/8250_bcm7271.c b/drivers/tty/serial/8250/8250_bcm7271.c index ed5a94747692..adb1a3247807 100644 --- a/drivers/tty/serial/8250/8250_bcm7271.c +++ b/drivers/tty/serial/8250/8250_bcm7271.c @@ -606,8 +606,10 @@ static int brcmuart_startup(struct uart_port *port) * Disable the Receive Data Interrupt because the DMA engine * will handle this. */ + spin_lock_irq(&port->lock); up->ier &= ~UART_IER_RDI; - serial_port_out(port, UART_IER, up->ier); + serial8250_set_IER(up, up->ier); + spin_unlock_irq(&port->lock); priv->tx_running = false; priv->dma.rx_dma = NULL; @@ -787,6 +789,12 @@ static int brcmuart_handle_irq(struct uart_port *p) spin_lock_irqsave(&p->lock, flags); status = serial_port_in(p, UART_LSR); if ((status & UART_LSR_DR) == 0) { + bool is_console; + + is_console = serial8250_is_console(port); + + if (is_console) + serial8250_enter_unsafe(p); ier = serial_port_in(p, UART_IER); /* @@ -807,6 +815,9 @@ static int brcmuart_handle_irq(struct uart_port *p) serial_port_in(p, UART_RX); } + if (is_console) + serial8250_exit_unsafe(p); + handled = 1; } spin_unlock_irqrestore(&p->lock, flags); @@ -844,12 +855,22 @@ static enum hrtimer_restart brcmuart_hrtimer_func(struct hrtimer *t) /* re-enable receive unless upper layer has disabled it */ if ((up->ier & (UART_IER_RLSI | UART_IER_RDI)) == (UART_IER_RLSI | UART_IER_RDI)) { + bool is_console; + + is_console = serial8250_is_console(port); + + if (is_console) + serial8250_enter_unsafe(p); + status = serial_port_in(p, UART_IER); status |= (UART_IER_RLSI | UART_IER_RDI); serial_port_out(p, UART_IER, status); status = serial_port_in(p, UART_MCR); status |= UART_MCR_RTS; serial_port_out(p, UART_MCR, status); + + if (is_console) + serial8250_exit_unsafe(p); } spin_unlock_irqrestore(&p->lock, flags); return HRTIMER_NORESTART; diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c index ab63c308be0a..688ecfc6e1d5 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -256,6 +256,7 @@ static void serial8250_timeout(struct timer_list *t) static void serial8250_backup_timeout(struct timer_list *t) { struct uart_8250_port *up = from_timer(up, t, timer); + struct uart_port *port = &up->port; unsigned int iir, ier = 0, lsr; unsigned long flags; @@ -266,8 +267,18 @@ static void serial8250_backup_timeout(struct timer_list *t) * based handler. */ if (up->port.irq) { + bool is_console; + + is_console = serial8250_is_console(port); + + if (is_console) + serial8250_enter_unsafe(up); + ier = serial_in(up, UART_IER); serial_out(up, UART_IER, 0); + + if (is_console) + serial8250_exit_unsafe(up); } iir = serial_in(up, UART_IIR); @@ -290,7 +301,7 @@ static void serial8250_backup_timeout(struct timer_list *t) serial8250_tx_chars(up); if (up->port.irq) - serial_out(up, UART_IER, ier); + serial8250_set_IER(up, ier); spin_unlock_irqrestore(&up->port.lock, flags); @@ -576,12 +587,30 @@ serial8250_register_ports(struct uart_driver *drv, struct device *dev) #ifdef CONFIG_SERIAL_8250_CONSOLE -static void univ8250_console_write(struct console *co, const char *s, - unsigned int count) +static void univ8250_console_port_lock(struct console *con, bool do_lock, unsigned long *flags) +{ + struct uart_8250_port *up = &serial8250_ports[con->index]; + + if (do_lock) + spin_lock_irqsave(&up->port.lock, *flags); + else + spin_unlock_irqrestore(&up->port.lock, *flags); +} + +static bool univ8250_console_write_atomic(struct console *co, + struct cons_write_context *wctxt) +{ + struct uart_8250_port *up = &serial8250_ports[co->index]; + + return serial8250_console_write_atomic(up, wctxt); +} + +static bool univ8250_console_write_thread(struct console *co, + struct cons_write_context *wctxt) { struct uart_8250_port *up = &serial8250_ports[co->index]; - serial8250_console_write(up, s, count); + return serial8250_console_write_thread(up, wctxt); } static int univ8250_console_setup(struct console *co, char *options) @@ -669,12 +698,14 @@ static int univ8250_console_match(struct console *co, char *name, int idx, static struct console univ8250_console = { .name = "ttyS", - .write = univ8250_console_write, + .write_atomic = univ8250_console_write_atomic, + .write_thread = univ8250_console_write_thread, + .port_lock = univ8250_console_port_lock, .device = uart_console_device, .setup = univ8250_console_setup, .exit = univ8250_console_exit, .match = univ8250_console_match, - .flags = CON_PRINTBUFFER | CON_ANYTIME, + .flags = CON_PRINTBUFFER | CON_ANYTIME | CON_NO_BKL, .index = -1, .data = &serial8250_reg, }; @@ -962,7 +993,7 @@ static void serial_8250_overrun_backoff_work(struct work_struct *work) spin_lock_irqsave(&port->lock, flags); up->ier |= UART_IER_RLSI | UART_IER_RDI; up->port.read_status_mask |= UART_LSR_DR; - serial_out(up, UART_IER, up->ier); + serial8250_set_IER(up, up->ier); spin_unlock_irqrestore(&port->lock, flags); } diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c index 64770c62bbec..ccb70b20b1f4 100644 --- a/drivers/tty/serial/8250/8250_exar.c +++ b/drivers/tty/serial/8250/8250_exar.c @@ -185,6 +185,10 @@ static void xr17v35x_set_divisor(struct uart_port *p, unsigned int baud, static int xr17v35x_startup(struct uart_port *port) { + struct uart_8250_port *up = up_to_u8250p(port); + + spin_lock_irq(&port->lock); + /* * First enable access to IER [7:5], ISR [5:4], FCR [5:4], * MCR [7:5] and MSR [7:0] @@ -195,7 +199,9 @@ static int xr17v35x_startup(struct uart_port *port) * Make sure all interrups are masked until initialization is * complete and the FIFOs are cleared */ - serial_port_out(port, UART_IER, 0); + serial8250_set_IER(up, 0); + + spin_unlock_irq(&port->lock); return serial8250_do_startup(port); } diff --git a/drivers/tty/serial/8250/8250_fsl.c b/drivers/tty/serial/8250/8250_fsl.c index 8aad15622a2e..74bb85b705e7 100644 --- a/drivers/tty/serial/8250/8250_fsl.c +++ b/drivers/tty/serial/8250/8250_fsl.c @@ -58,7 +58,8 @@ int fsl8250_handle_irq(struct uart_port *port) if ((orig_lsr & UART_LSR_OE) && (up->overrun_backoff_time_ms > 0)) { unsigned long delay; - up->ier = port->serial_in(port, UART_IER); + up->ier = serial8250_in_IER(up); + if (up->ier & (UART_IER_RLSI | UART_IER_RDI)) { port->ops->stop_rx(port); } else { diff --git a/drivers/tty/serial/8250/8250_ingenic.c b/drivers/tty/serial/8250/8250_ingenic.c index 617b8ce60d6b..548904c3d11b 100644 --- a/drivers/tty/serial/8250/8250_ingenic.c +++ b/drivers/tty/serial/8250/8250_ingenic.c @@ -171,6 +171,7 @@ OF_EARLYCON_DECLARE(x1000_uart, "ingenic,x1000-uart", static void ingenic_uart_serial_out(struct uart_port *p, int offset, int value) { + struct uart_8250_port *up = up_to_u8250p(p); int ier; switch (offset) { @@ -192,7 +193,7 @@ static void ingenic_uart_serial_out(struct uart_port *p, int offset, int value) * If we have enabled modem status IRQs we should enable * modem mode. */ - ier = p->serial_in(p, UART_IER); + ier = serial8250_in_IER(up); if (ier & UART_IER_MSI) value |= UART_MCR_MDCE | UART_MCR_FCM; diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c index fb1d5ec0940e..bf7ab55c8923 100644 --- a/drivers/tty/serial/8250/8250_mtk.c +++ b/drivers/tty/serial/8250/8250_mtk.c @@ -222,12 +222,38 @@ static void mtk8250_shutdown(struct uart_port *port) static void mtk8250_disable_intrs(struct uart_8250_port *up, int mask) { - serial_out(up, UART_IER, serial_in(up, UART_IER) & (~mask)); + struct uart_port *port = &up->port; + bool is_console; + int ier; + + is_console = serial8250_is_console(port); + + if (is_console) + serial8250_enter_unsafe(up); + + ier = serial_in(up, UART_IER); + serial_out(up, UART_IER, ier & (~mask)); + + if (is_console) + serial8250_exit_unsafe(up); } static void mtk8250_enable_intrs(struct uart_8250_port *up, int mask) { - serial_out(up, UART_IER, serial_in(up, UART_IER) | mask); + struct uart_port *port = &up->port; + bool is_console; + int ier; + + is_console = serial8250_is_console(port); + + if (is_console) + serial8250_enter_unsafe(up); + + ier = serial_in(up, UART_IER); + serial_out(up, UART_IER, ier | mask); + + if (is_console) + serial8250_exit_unsafe(up); } static void mtk8250_set_flow_ctrl(struct uart_8250_port *up, int mode) diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c index 734f092ef839..bfa50a26349d 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -334,8 +334,7 @@ static void omap8250_restore_regs(struct uart_8250_port *up) /* drop TCR + TLR access, we setup XON/XOFF later */ serial8250_out_MCR(up, mcr); - - serial_out(up, UART_IER, up->ier); + serial8250_set_IER(up, up->ier); serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B); serial_dl_write(up, priv->quot); @@ -523,16 +522,21 @@ static void omap_8250_pm(struct uart_port *port, unsigned int state, u8 efr; pm_runtime_get_sync(port->dev); + + spin_lock_irq(&port->lock); + serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B); efr = serial_in(up, UART_EFR); serial_out(up, UART_EFR, efr | UART_EFR_ECB); serial_out(up, UART_LCR, 0); - serial_out(up, UART_IER, (state != 0) ? UART_IERX_SLEEP : 0); + serial8250_set_IER(up, (state != 0) ? UART_IERX_SLEEP : 0); serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B); serial_out(up, UART_EFR, efr); serial_out(up, UART_LCR, 0); + spin_unlock_irq(&port->lock); + pm_runtime_mark_last_busy(port->dev); pm_runtime_put_autosuspend(port->dev); } @@ -649,7 +653,8 @@ static irqreturn_t omap8250_irq(int irq, void *dev_id) if ((lsr & UART_LSR_OE) && up->overrun_backoff_time_ms > 0) { unsigned long delay; - up->ier = port->serial_in(port, UART_IER); + spin_lock(&port->lock); + up->ier = serial8250_in_IER(up); if (up->ier & (UART_IER_RLSI | UART_IER_RDI)) { port->ops->stop_rx(port); } else { @@ -658,6 +663,7 @@ static irqreturn_t omap8250_irq(int irq, void *dev_id) */ cancel_delayed_work(&up->overrun_backoff); } + spin_unlock(&port->lock); delay = msecs_to_jiffies(up->overrun_backoff_time_ms); schedule_delayed_work(&up->overrun_backoff, delay); @@ -707,8 +713,10 @@ static int omap_8250_startup(struct uart_port *port) if (ret < 0) goto err; + spin_lock_irq(&port->lock); up->ier = UART_IER_RLSI | UART_IER_RDI; - serial_out(up, UART_IER, up->ier); + serial8250_set_IER(up, up->ier); + spin_unlock_irq(&port->lock); #ifdef CONFIG_PM up->capabilities |= UART_CAP_RPM; @@ -748,8 +756,10 @@ static void omap_8250_shutdown(struct uart_port *port) if (priv->habit & UART_HAS_EFR2) serial_out(up, UART_OMAP_EFR2, 0x0); + spin_lock_irq(&port->lock); up->ier = 0; - serial_out(up, UART_IER, 0); + serial8250_set_IER(up, 0); + spin_unlock_irq(&port->lock); if (up->dma) serial8250_release_dma(up); @@ -797,7 +807,7 @@ static void omap_8250_unthrottle(struct uart_port *port) up->dma->rx_dma(up); up->ier |= UART_IER_RLSI | UART_IER_RDI; port->read_status_mask |= UART_LSR_DR; - serial_out(up, UART_IER, up->ier); + serial8250_set_IER(up, up->ier); spin_unlock_irqrestore(&port->lock, flags); pm_runtime_mark_last_busy(port->dev); @@ -956,7 +966,7 @@ static void __dma_rx_complete(void *param) __dma_rx_do_complete(p); if (!priv->throttled) { p->ier |= UART_IER_RLSI | UART_IER_RDI; - serial_out(p, UART_IER, p->ier); + serial8250_set_IER(p, p->ier); if (!(priv->habit & UART_HAS_EFR2)) omap_8250_rx_dma(p); } @@ -1013,7 +1023,7 @@ static int omap_8250_rx_dma(struct uart_8250_port *p) * callback to run. */ p->ier &= ~(UART_IER_RLSI | UART_IER_RDI); - serial_out(p, UART_IER, p->ier); + serial8250_set_IER(p, p->ier); } goto out; } @@ -1226,12 +1236,12 @@ static void am654_8250_handle_rx_dma(struct uart_8250_port *up, u8 iir, * periodic timeouts, re-enable interrupts. */ up->ier &= ~(UART_IER_RLSI | UART_IER_RDI); - serial_out(up, UART_IER, up->ier); + serial8250_set_IER(up, up->ier); omap_8250_rx_dma_flush(up); serial_in(up, UART_IIR); serial_out(up, UART_OMAP_EFR2, 0x0); up->ier |= UART_IER_RLSI | UART_IER_RDI; - serial_out(up, UART_IER, up->ier); + serial8250_set_IER(up, up->ier); } } @@ -1717,12 +1727,16 @@ static int omap8250_runtime_resume(struct device *dev) up = serial8250_get_port(priv->line); + spin_lock_irq(&up->port.lock); + if (omap8250_lost_context(up)) omap8250_restore_regs(up); if (up->dma && up->dma->rxchan && !(priv->habit & UART_HAS_EFR2)) omap_8250_rx_dma(up); + spin_unlock_irq(&up->port.lock); + priv->latency = priv->calc_latency; schedule_work(&priv->qos_work); return 0; diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index fa43df05342b..f1976d9a8a38 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -744,6 +744,7 @@ static void serial8250_set_sleep(struct uart_8250_port *p, int sleep) serial8250_rpm_get(p); if (p->capabilities & UART_CAP_SLEEP) { + spin_lock_irq(&p->port.lock); if (p->capabilities & UART_CAP_EFR) { lcr = serial_in(p, UART_LCR); efr = serial_in(p, UART_EFR); @@ -751,25 +752,18 @@ static void serial8250_set_sleep(struct uart_8250_port *p, int sleep) serial_out(p, UART_EFR, UART_EFR_ECB); serial_out(p, UART_LCR, 0); } - serial_out(p, UART_IER, sleep ? UART_IERX_SLEEP : 0); + serial8250_set_IER(p, sleep ? UART_IERX_SLEEP : 0); if (p->capabilities & UART_CAP_EFR) { serial_out(p, UART_LCR, UART_LCR_CONF_MODE_B); serial_out(p, UART_EFR, efr); serial_out(p, UART_LCR, lcr); } + spin_unlock_irq(&p->port.lock); } serial8250_rpm_put(p); } -static void serial8250_clear_IER(struct uart_8250_port *up) -{ - if (up->capabilities & UART_CAP_UUE) - serial_out(up, UART_IER, UART_IER_UUE); - else - serial_out(up, UART_IER, 0); -} - #ifdef CONFIG_SERIAL_8250_RSA /* * Attempts to turn on the RSA FIFO. Returns zero on failure. @@ -1033,8 +1027,10 @@ static int broken_efr(struct uart_8250_port *up) */ static void autoconfig_16550a(struct uart_8250_port *up) { + struct uart_port *port = &up->port; unsigned char status1, status2; unsigned int iersave; + bool is_console; up->port.type = PORT_16550A; up->capabilities |= UART_CAP_FIFO; @@ -1150,6 +1146,11 @@ static void autoconfig_16550a(struct uart_8250_port *up) return; } + is_console = serial8250_is_console(port); + + if (is_console) + serial8250_enter_unsafe(up); + /* * Try writing and reading the UART_IER_UUE bit (b6). * If it works, this is probably one of the Xscale platform's @@ -1185,6 +1186,9 @@ static void autoconfig_16550a(struct uart_8250_port *up) } serial_out(up, UART_IER, iersave); + if (is_console) + serial8250_exit_unsafe(up); + /* * We distinguish between 16550A and U6 16550A by counting * how many bytes are in the FIFO. @@ -1226,6 +1230,13 @@ static void autoconfig(struct uart_8250_port *up) up->bugs = 0; if (!(port->flags & UPF_BUGGY_UART)) { + bool is_console; + + is_console = serial8250_is_console(port); + + if (is_console) + serial8250_enter_unsafe(up); + /* * Do a simple existence test first; if we fail this, * there's no point trying anything else. @@ -1255,6 +1266,10 @@ static void autoconfig(struct uart_8250_port *up) #endif scratch3 = serial_in(up, UART_IER) & UART_IER_ALL_INTR; serial_out(up, UART_IER, scratch); + + if (is_console) + serial8250_exit_unsafe(up); + if (scratch2 != 0 || scratch3 != UART_IER_ALL_INTR) { /* * We failed; there's nothing here @@ -1376,6 +1391,7 @@ static void autoconfig_irq(struct uart_8250_port *up) unsigned char save_ICP = 0; unsigned int ICP = 0; unsigned long irqs; + bool is_console; int irq; if (port->flags & UPF_FOURPORT) { @@ -1385,8 +1401,12 @@ static void autoconfig_irq(struct uart_8250_port *up) inb_p(ICP); } - if (uart_console(port)) + is_console = serial8250_is_console(port); + + if (is_console) { console_lock(); + serial8250_enter_unsafe(up); + } /* forget possible initially masked and pending IRQ */ probe_irq_off(probe_irq_on()); @@ -1418,8 +1438,10 @@ static void autoconfig_irq(struct uart_8250_port *up) if (port->flags & UPF_FOURPORT) outb_p(save_ICP, ICP); - if (uart_console(port)) + if (is_console) { + serial8250_exit_unsafe(up); console_unlock(); + } port->irq = (irq > 0) ? irq : 0; } @@ -1432,7 +1454,7 @@ static void serial8250_stop_rx(struct uart_port *port) up->ier &= ~(UART_IER_RLSI | UART_IER_RDI); up->port.read_status_mask &= ~UART_LSR_DR; - serial_port_out(port, UART_IER, up->ier); + serial8250_set_IER(up, up->ier); serial8250_rpm_put(up); } @@ -1462,7 +1484,7 @@ void serial8250_em485_stop_tx(struct uart_8250_port *p) serial8250_clear_and_reinit_fifos(p); p->ier |= UART_IER_RLSI | UART_IER_RDI; - serial_port_out(&p->port, UART_IER, p->ier); + serial8250_set_IER(p, p->ier); } } EXPORT_SYMBOL_GPL(serial8250_em485_stop_tx); @@ -1709,7 +1731,7 @@ static void serial8250_disable_ms(struct uart_port *port) mctrl_gpio_disable_ms(up->gpios); up->ier &= ~UART_IER_MSI; - serial_port_out(port, UART_IER, up->ier); + serial8250_set_IER(up, up->ier); } static void serial8250_enable_ms(struct uart_port *port) @@ -1725,7 +1747,7 @@ static void serial8250_enable_ms(struct uart_port *port) up->ier |= UART_IER_MSI; serial8250_rpm_get(up); - serial_port_out(port, UART_IER, up->ier); + serial8250_set_IER(up, up->ier); serial8250_rpm_put(up); } @@ -2160,9 +2182,10 @@ static void serial8250_put_poll_char(struct uart_port *port, serial8250_rpm_get(up); /* * First save the IER then disable the interrupts + * + * Best-effort IER access because other CPUs are quiesced. */ - ier = serial_port_in(port, UART_IER); - serial8250_clear_IER(up); + __serial8250_clear_IER(up, NULL, &ier); wait_for_xmitr(up, UART_LSR_BOTH_EMPTY); /* @@ -2175,7 +2198,7 @@ static void serial8250_put_poll_char(struct uart_port *port, * and restore the IER */ wait_for_xmitr(up, UART_LSR_BOTH_EMPTY); - serial_port_out(port, UART_IER, ier); + __serial8250_set_IER(up, NULL, ier); serial8250_rpm_put(up); } @@ -2186,6 +2209,7 @@ int serial8250_do_startup(struct uart_port *port) struct uart_8250_port *up = up_to_u8250p(port); unsigned long flags; unsigned char iir; + bool is_console; int retval; u16 lsr; @@ -2203,21 +2227,25 @@ int serial8250_do_startup(struct uart_port *port) serial8250_rpm_get(up); if (port->type == PORT_16C950) { /* Wake up and initialize UART */ + spin_lock_irqsave(&port->lock, flags); up->acr = 0; serial_port_out(port, UART_LCR, UART_LCR_CONF_MODE_B); serial_port_out(port, UART_EFR, UART_EFR_ECB); - serial_port_out(port, UART_IER, 0); + serial8250_set_IER(up, 0); serial_port_out(port, UART_LCR, 0); serial_icr_write(up, UART_CSR, 0); /* Reset the UART */ serial_port_out(port, UART_LCR, UART_LCR_CONF_MODE_B); serial_port_out(port, UART_EFR, UART_EFR_ECB); serial_port_out(port, UART_LCR, 0); + spin_unlock_irqrestore(&port->lock, flags); } if (port->type == PORT_DA830) { /* Reset the port */ - serial_port_out(port, UART_IER, 0); + spin_lock_irqsave(&port->lock, flags); + serial8250_set_IER(up, 0); serial_port_out(port, UART_DA830_PWREMU_MGMT, 0); + spin_unlock_irqrestore(&port->lock, flags); mdelay(10); /* Enable Tx, Rx and free run mode */ @@ -2315,6 +2343,8 @@ int serial8250_do_startup(struct uart_port *port) if (retval) goto out; + is_console = serial8250_is_console(port); + if (port->irq && !(up->port.flags & UPF_NO_THRE_TEST)) { unsigned char iir1; @@ -2331,6 +2361,9 @@ int serial8250_do_startup(struct uart_port *port) */ spin_lock_irqsave(&port->lock, flags); + if (is_console) + serial8250_enter_unsafe(up); + wait_for_xmitr(up, UART_LSR_THRE); serial_port_out_sync(port, UART_IER, UART_IER_THRI); udelay(1); /* allow THRE to set */ @@ -2341,6 +2374,9 @@ int serial8250_do_startup(struct uart_port *port) iir = serial_port_in(port, UART_IIR); serial_port_out(port, UART_IER, 0); + if (is_console) + serial8250_exit_unsafe(up); + spin_unlock_irqrestore(&port->lock, flags); if (port->irqflags & IRQF_SHARED) @@ -2395,10 +2431,14 @@ int serial8250_do_startup(struct uart_port *port) * Do a quick test to see if we receive an interrupt when we enable * the TX irq. */ + if (is_console) + serial8250_enter_unsafe(up); serial_port_out(port, UART_IER, UART_IER_THRI); lsr = serial_port_in(port, UART_LSR); iir = serial_port_in(port, UART_IIR); serial_port_out(port, UART_IER, 0); + if (is_console) + serial8250_exit_unsafe(up); if (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT) { if (!(up->bugs & UART_BUG_TXEN)) { @@ -2430,7 +2470,7 @@ int serial8250_do_startup(struct uart_port *port) if (up->dma) { const char *msg = NULL; - if (uart_console(port)) + if (is_console) msg = "forbid DMA for kernel console"; else if (serial8250_request_dma(up)) msg = "failed to request DMA"; @@ -2481,7 +2521,7 @@ void serial8250_do_shutdown(struct uart_port *port) */ spin_lock_irqsave(&port->lock, flags); up->ier = 0; - serial_port_out(port, UART_IER, 0); + serial8250_set_IER(up, 0); spin_unlock_irqrestore(&port->lock, flags); synchronize_irq(port->irq); @@ -2847,7 +2887,7 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios, if (up->capabilities & UART_CAP_RTOIE) up->ier |= UART_IER_RTOIE; - serial_port_out(port, UART_IER, up->ier); + serial8250_set_IER(up, up->ier); if (up->capabilities & UART_CAP_EFR) { unsigned char efr = 0; @@ -3312,12 +3352,21 @@ EXPORT_SYMBOL_GPL(serial8250_set_defaults); #ifdef CONFIG_SERIAL_8250_CONSOLE -static void serial8250_console_putchar(struct uart_port *port, unsigned char ch) +static bool serial8250_console_putchar(struct uart_port *port, unsigned char ch, + struct cons_write_context *wctxt) { struct uart_8250_port *up = up_to_u8250p(port); wait_for_xmitr(up, UART_LSR_THRE); + if (!console_can_proceed(wctxt)) + return false; serial_port_out(port, UART_TX, ch); + if (ch == '\n') + up->console_newline_needed = false; + else + up->console_newline_needed = true; + + return true; } /* @@ -3346,33 +3395,134 @@ static void serial8250_console_restore(struct uart_8250_port *up) serial8250_out_MCR(up, up->mcr | UART_MCR_DTR | UART_MCR_RTS); } +static bool __serial8250_console_write(struct uart_port *port, struct cons_write_context *wctxt, + const char *s, unsigned int count, + bool (*putchar)(struct uart_port *, unsigned char, struct cons_write_context *)) +{ + bool finished = false; + unsigned int i; + + for (i = 0; i < count; i++, s++) { + if (*s == '\n') { + if (!putchar(port, '\r', wctxt)) + goto out; + } + if (!putchar(port, *s, wctxt)) + goto out; + } + finished = true; +out: + return finished; +} + +static bool serial8250_console_write(struct uart_port *port, struct cons_write_context *wctxt, + const char *s, unsigned int count, + bool (*putchar)(struct uart_port *, unsigned char, struct cons_write_context *)) +{ + return __serial8250_console_write(port, wctxt, s, count, putchar); +} + +static bool atomic_print_line(struct uart_8250_port *up, + struct cons_write_context *wctxt) +{ + struct uart_port *port = &up->port; + char buf[4]; + + if (up->console_newline_needed && + !__serial8250_console_write(port, wctxt, "\n", 1, serial8250_console_putchar)) { + return false; + } + + sprintf(buf, "A%d", raw_smp_processor_id()); + if (!__serial8250_console_write(port, wctxt, buf, strlen(buf), serial8250_console_putchar)) + return false; + + return __serial8250_console_write(port, wctxt, wctxt->outbuf, wctxt->len, + serial8250_console_putchar); +} + +static void atomic_console_reacquire(struct cons_write_context *wctxt, + struct cons_write_context *wctxt_init) +{ + memcpy(wctxt, wctxt_init, sizeof(*wctxt)); + while (!console_try_acquire(wctxt)) { + cpu_relax(); + memcpy(wctxt, wctxt_init, sizeof(*wctxt)); + } +} + /* - * Print a string to the serial port using the device FIFO - * - * It sends fifosize bytes and then waits for the fifo - * to get empty. + * It should be possible to support a hostile takeover in an unsafe + * section if it is write_atomic() that is being taken over. But where + * to put this policy? */ -static void serial8250_console_fifo_write(struct uart_8250_port *up, - const char *s, unsigned int count) +bool serial8250_console_write_atomic(struct uart_8250_port *up, + struct cons_write_context *wctxt) { - int i; - const char *end = s + count; - unsigned int fifosize = up->tx_loadsz; - bool cr_sent = false; - - while (s != end) { - wait_for_lsr(up, UART_LSR_THRE); - - for (i = 0; i < fifosize && s != end; ++i) { - if (*s == '\n' && !cr_sent) { - serial_out(up, UART_TX, '\r'); - cr_sent = true; - } else { - serial_out(up, UART_TX, *s++); - cr_sent = false; - } + struct cons_write_context wctxt_init = {}; + struct cons_context *ctxt_init = &ACCESS_PRIVATE(&wctxt_init, ctxt); + struct cons_context *ctxt = &ACCESS_PRIVATE(wctxt, ctxt); + bool can_print = true; + unsigned int ier; + + /* With write_atomic, another context may hold the port->lock. */ + + ctxt_init->console = ctxt->console; + ctxt_init->prio = ctxt->prio; + ctxt_init->thread = ctxt->thread; + + touch_nmi_watchdog(); + + /* + * Enter unsafe in order to disable interrupts. If the console is + * lost before the interrupts are disabled, bail out because another + * context took over the printing. If the console is lost after the + * interrutps are disabled, the console must be reacquired in order + * to re-enable the interrupts. However in that case no printing is + * allowed because another context took over the printing. + */ + + if (!console_enter_unsafe(wctxt)) + return false; + + if (!__serial8250_clear_IER(up, wctxt, &ier)) + return false; + + if (console_exit_unsafe(wctxt)) { + can_print = atomic_print_line(up, wctxt); + if (!can_print) + atomic_console_reacquire(wctxt, &wctxt_init); + + if (can_print) { + can_print = console_can_proceed(wctxt); + if (can_print) + wait_for_xmitr(up, UART_LSR_BOTH_EMPTY); + else + atomic_console_reacquire(wctxt, &wctxt_init); + } + } else { + atomic_console_reacquire(wctxt, &wctxt_init); + } + + /* + * Enter unsafe in order to enable interrupts. If the console is + * lost before the interrupts are enabled, the console must be + * reacquired in order to re-enable the interrupts. + */ + + for (;;) { + if (console_enter_unsafe(wctxt) && + __serial8250_set_IER(up, wctxt, ier)) { + break; } + + /* HW-IRQs still disabled. Reacquire to enable them. */ + atomic_console_reacquire(wctxt, &wctxt_init); } + + console_exit_unsafe(wctxt); + + return can_print; } /* @@ -3384,64 +3534,54 @@ static void serial8250_console_fifo_write(struct uart_8250_port *up, * Doing runtime PM is really a bad idea for the kernel console. * Thus, we assume the function is called when device is powered up. */ -void serial8250_console_write(struct uart_8250_port *up, const char *s, - unsigned int count) +bool serial8250_console_write_thread(struct uart_8250_port *up, + struct cons_write_context *wctxt) { struct uart_8250_em485 *em485 = up->em485; struct uart_port *port = &up->port; - unsigned long flags; - unsigned int ier, use_fifo; - int locked = 1; - - touch_nmi_watchdog(); - - if (oops_in_progress) - locked = spin_trylock_irqsave(&port->lock, flags); - else - spin_lock_irqsave(&port->lock, flags); + unsigned int count = wctxt->len; + const char *s = wctxt->outbuf; + bool finished = false; + unsigned int ier; + char buf[4]; /* * First save the IER then disable the interrupts */ - ier = serial_port_in(port, UART_IER); - serial8250_clear_IER(up); + if (!console_enter_unsafe(wctxt) || + !__serial8250_clear_IER(up, wctxt, &ier)) { + goto out; + } + if (!console_exit_unsafe(wctxt)) + goto out; /* check scratch reg to see if port powered off during system sleep */ if (up->canary && (up->canary != serial_port_in(port, UART_SCR))) { + if (!console_enter_unsafe(wctxt)) + goto out; serial8250_console_restore(up); + if (!console_exit_unsafe(wctxt)) + goto out; up->canary = 0; } if (em485) { - if (em485->tx_stopped) + if (em485->tx_stopped) { + if (!console_enter_unsafe(wctxt)) + goto out; up->rs485_start_tx(up); - mdelay(port->rs485.delay_rts_before_send); + if (!console_exit_unsafe(wctxt)) + goto out; + } + mdelay(port->rs485.delay_rts_before_send); /* WTF?! Seriously?! */ } - use_fifo = (up->capabilities & UART_CAP_FIFO) && - /* - * BCM283x requires to check the fifo - * after each byte. - */ - !(up->capabilities & UART_CAP_MINI) && - /* - * tx_loadsz contains the transmit fifo size - */ - up->tx_loadsz > 1 && - (up->fcr & UART_FCR_ENABLE_FIFO) && - port->state && - test_bit(TTY_PORT_INITIALIZED, &port->state->port.iflags) && - /* - * After we put a data in the fifo, the controller will send - * it regardless of the CTS state. Therefore, only use fifo - * if we don't use control flow. - */ - !(up->port.flags & UPF_CONS_FLOW); + sprintf(buf, "T%d", raw_smp_processor_id()); + if (serial8250_console_write(port, wctxt, buf, strlen(buf), serial8250_console_putchar)) + finished = serial8250_console_write(port, wctxt, s, count, serial8250_console_putchar); - if (likely(use_fifo)) - serial8250_console_fifo_write(up, s, count); - else - uart_console_write(port, s, count, serial8250_console_putchar); + if (!finished) + goto out; /* * Finally, wait for transmitter to become empty @@ -3450,12 +3590,20 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s, wait_for_xmitr(up, UART_LSR_BOTH_EMPTY); if (em485) { - mdelay(port->rs485.delay_rts_after_send); - if (em485->tx_stopped) + mdelay(port->rs485.delay_rts_after_send); /* WTF?! Seriously?! */ + if (em485->tx_stopped) { + if (!console_enter_unsafe(wctxt)) + goto out; up->rs485_stop_tx(up); + if (!console_exit_unsafe(wctxt)) + goto out; + } } - - serial_port_out(port, UART_IER, ier); + if (!console_enter_unsafe(wctxt)) + goto out; + WARN_ON_ONCE(!__serial8250_set_IER(up, wctxt, ier)); + if (!console_exit_unsafe(wctxt)) + goto out; /* * The receive handling will happen properly because the @@ -3464,11 +3612,15 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s, * call it if we have saved something in the saved flags * while processing with interrupts off. */ - if (up->msr_saved_flags) + if (up->msr_saved_flags) { + if (!console_enter_unsafe(wctxt)) + goto out; serial8250_modem_status(up); - - if (locked) - spin_unlock_irqrestore(&port->lock, flags); + if (!console_exit_unsafe(wctxt)) + goto out; + } +out: + return finished; } static unsigned int probe_baud(struct uart_port *port) @@ -3488,6 +3640,7 @@ static unsigned int probe_baud(struct uart_port *port) int serial8250_console_setup(struct uart_port *port, char *options, bool probe) { + struct uart_8250_port *up = up_to_u8250p(port); int baud = 9600; int bits = 8; int parity = 'n'; @@ -3497,6 +3650,8 @@ int serial8250_console_setup(struct uart_port *port, char *options, bool probe) if (!port->iobase && !port->membase) return -ENODEV; + up->console_newline_needed = false; + if (options) uart_parse_options(options, &baud, &parity, &bits, &flow); else if (probe) diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig index 978dc196c29b..22656e8370ea 100644 --- a/drivers/tty/serial/8250/Kconfig +++ b/drivers/tty/serial/8250/Kconfig @@ -9,6 +9,7 @@ config SERIAL_8250 depends on !S390 select SERIAL_CORE select SERIAL_MCTRL_GPIO if GPIOLIB + select HAVE_ATOMIC_CONSOLE help This selects whether you want to include the driver for the standard serial ports. The standard answer is Y. People who might say N diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 2bd32c8ece39..9901f916dc1a 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -2336,8 +2336,11 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport) * able to Re-start_rx later. */ if (!console_suspend_enabled && uart_console(uport)) { - if (uport->ops->start_rx) + if (uport->ops->start_rx) { + spin_lock_irq(&uport->lock); uport->ops->stop_rx(uport); + spin_unlock_irq(&uport->lock); + } goto unlock; } @@ -2430,8 +2433,11 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport) if (console_suspend_enabled) uart_change_pm(state, UART_PM_STATE_ON); uport->ops->set_termios(uport, &termios, NULL); - if (!console_suspend_enabled && uport->ops->start_rx) + if (!console_suspend_enabled && uport->ops->start_rx) { + spin_lock_irq(&uport->lock); uport->ops->start_rx(uport); + spin_unlock_irq(&uport->lock); + } if (console_suspend_enabled) console_start(uport->cons); } diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h index 19376bee9667..9055a22992ed 100644 --- a/include/linux/serial_8250.h +++ b/include/linux/serial_8250.h @@ -125,6 +125,8 @@ struct uart_8250_port { #define MSR_SAVE_FLAGS UART_MSR_ANY_DELTA unsigned char msr_saved_flags; + bool console_newline_needed; + struct uart_8250_dma *dma; const struct uart_8250_ops *ops; @@ -139,6 +141,9 @@ struct uart_8250_port { /* Serial port overrun backoff */ struct delayed_work overrun_backoff; u32 overrun_backoff_time_ms; + + struct cons_write_context wctxt; + int cookie; }; static inline struct uart_8250_port *up_to_u8250p(struct uart_port *up) @@ -178,8 +183,10 @@ void serial8250_tx_chars(struct uart_8250_port *up); unsigned int serial8250_modem_status(struct uart_8250_port *up); void serial8250_init_port(struct uart_8250_port *up); void serial8250_set_defaults(struct uart_8250_port *up); -void serial8250_console_write(struct uart_8250_port *up, const char *s, - unsigned int count); +bool serial8250_console_write_atomic(struct uart_8250_port *up, + struct cons_write_context *wctxt); +bool serial8250_console_write_thread(struct uart_8250_port *up, + struct cons_write_context *wctxt); int serial8250_console_setup(struct uart_port *port, char *options, bool probe); int serial8250_console_exit(struct uart_port *port);