From patchwork Wed Jan 8 00:47:30 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Toshiyuki Sato X-Patchwork-Id: 13929732 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B23C3E77197 for ; Wed, 8 Jan 2025 00:52:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-Type: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=A/B0lFPcENBxS4FEb8EDKILhK0N1bRr3Xra/0nwevUc=; b=WkyjjyQFdc8wUuXzZA/Oz1l6eM YdItpr5yy9H9df4lmftjW00ocWk4Aj9vojjMmoH8st//tuQ/ORDJxds4Mz7I3bHpMf6TSiTMAuFz+ FstqhvaGSrrT/SrFSdZSpq3Kn89CgmZuBxaZhH51x5oVSI+Oj9lFOeGRkEnXIeqGvC1J46iCnRRt4 idnEbw3VBXW/2GPvBFyiAfmVsfKaJ5sMnMxDCuaT2a5khIav+mt6sAAzZV0SdXohFoq+ZCf+HGGbI tsUJEW+3KU6exFN/SK949coIze1VGvn4mtsQHV+Xv9tXyS7OsQRR1Rd3Ya8R7vY+1cd578gOyk9C4 KUVuYZcg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tVKIX-00000006fBA-1CaO; Wed, 08 Jan 2025 00:51:49 +0000 Received: from esa10.hc1455-7.c3s2.iphmx.com ([139.138.36.225]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tVKHJ-00000006f2a-3jM6 for linux-arm-kernel@lists.infradead.org; Wed, 08 Jan 2025 00:50:35 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=fujitsu.com; i=@fujitsu.com; q=dns/txt; s=fj2; t=1736297434; x=1767833434; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=3pepWCQ/w0pYqD518g7xPAZwkgW7P/rUAva7kIPw9e8=; b=Hb6xl9VUq3aR1bYUnfzk/0x+BA8xi9ZOKVOzSza5PIC/JBqzcqspV00o HV28FHhurkY8f3Fy96B4JPcJOJdajiv6bKC/eqdcMoYnrctHY0O/Be2sV FIRjaoGfVoW2w4HUmewHitVIQsBRuq+ASUGk0Ktb4tkMWNPLn74jIqrb9 h4ml1xesO0qMRl/oVH1v+qtKcoVW60CVEIs+IbXOgwnRFELLQlYRfqN4D zpjZ73eP6vkoM/CY62peKvNVLGIF6Eaop5MDZIRCWjQOc7iruUp46jkhG f22tAP84aRPLPFQzYXcNAhyTN9M1yuBzUA89cWYdKgSPHr2laCb30gwp3 w==; X-CSE-ConnectionGUID: mgs+iD5DSoaTnM2oEHvo5A== X-CSE-MsgGUID: fuULeX+5R2O5HCu1+1HCMw== X-IronPort-AV: E=McAfee;i="6700,10204,11308"; a="173201864" X-IronPort-AV: E=Sophos;i="6.12,296,1728918000"; d="scan'208";a="173201864" Received: from unknown (HELO yto-r1.gw.nic.fujitsu.com) ([218.44.52.217]) by esa10.hc1455-7.c3s2.iphmx.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jan 2025 09:50:27 +0900 Received: from yto-m2.gw.nic.fujitsu.com (yto-nat-yto-m2.gw.nic.fujitsu.com [192.168.83.65]) by yto-r1.gw.nic.fujitsu.com (Postfix) with ESMTP id CD416DF502 for ; Wed, 8 Jan 2025 09:50:24 +0900 (JST) Received: from yto-om4.fujitsu.com (yto-om4.o.css.fujitsu.com [10.128.89.165]) by yto-m2.gw.nic.fujitsu.com (Postfix) with ESMTP id 9F98AD5083 for ; Wed, 8 Jan 2025 09:50:24 +0900 (JST) Received: from sm-x86-mem01.ssoft.mng.com (sm-x86-stp01.soft.fujitsu.com [10.124.178.20]) by yto-om4.fujitsu.com (Postfix) with ESMTP id 6FCDC40054C45; Wed, 8 Jan 2025 09:50:24 +0900 (JST) From: Toshiyuki Sato To: Russell King , Greg Kroah-Hartman , Jiri Slaby Cc: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, linux-arm-kernel@lists.infradead.org, fj6611ie@aa.jp.fujitsu.com Subject: [PATCH] serial: amba-pl011: Implement nbcon console Date: Wed, 8 Jan 2025 00:47:30 +0000 Message-Id: <20250108004730.2302996-1-fj6611ie@aa.jp.fujitsu.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250107_165034_215734_23D3891A X-CRM114-Status: GOOD ( 22.40 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Implement the callbacks required for an NBCON console [0] on the amba-pl011 console driver. The codes for legacy console are retained, and the module parameter (use_nbcon) allows switching between legacy and NBCON. The default is off (use legacy console) for now. Referred to the NBCON implementation work for 8250 [1] and imx [2]. The normal-priority write_thread checks for console ownership each time a character is printed. write_atomic holds the console ownership until the entire string is printed. UART register operations are protected from other contexts by uart_port_lock, except for a final flush(nbcon_atomic_flush_unsafe) on panic. The patch has been verified to correctly handle the output and competition of messages with different priorities and flushing panic message to console after nmi panic using ARM64 QEMU and a physical machine(A64FX). [0] https://lore.kernel.org/all/ZuRRTbapH0DCj334@pathway.suse.cz/ [1] https://lore.kernel.org/all/20240913140538.221708-1-john.ogness@linutronix.de/T/ [2] https://lore.kernel.org/linux-arm-kernel/20240913-serial-imx-nbcon-v3-1-4c627302335b@geanix.com/T/ Signed-off-by: Toshiyuki Sato --- drivers/tty/serial/amba-pl011.c | 113 ++++++++++++++++++++++++++++++++ 1 file changed, 113 insertions(+) diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index 69b7a3e1e..52fab3170 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -41,6 +41,7 @@ #include #include #include +#include #define UART_NR 14 @@ -263,6 +264,7 @@ struct uart_amba_port { char type[12]; bool rs485_tx_started; unsigned int rs485_tx_drain_interval; /* usecs */ + bool console_line_ended; #ifdef CONFIG_DMA_ENGINE /* DMA stuff */ unsigned int dmacr; /* dma control reg */ @@ -274,6 +276,10 @@ struct uart_amba_port { #endif }; +/* if non-zero, the console is nbcon. */ +static int use_nbcon; +module_param(use_nbcon, int, 0444); + static unsigned int pl011_tx_empty(struct uart_port *port); static unsigned int pl011_reg_to_offset(const struct uart_amba_port *uap, @@ -2305,6 +2311,7 @@ static void pl011_console_putchar(struct uart_port *port, unsigned char ch) while (pl011_read(uap, REG_FR) & UART01x_FR_TXFF) cpu_relax(); pl011_write(ch, uap, REG_DR); + uap->console_line_ended = (ch == '\n'); } static void @@ -2411,6 +2418,8 @@ static int pl011_console_setup(struct console *co, char *options) if (ret) return ret; + uap->console_line_ended = true; + if (dev_get_platdata(uap->port.dev)) { struct amba_pl011_data *plat; @@ -2494,6 +2503,106 @@ static int pl011_console_match(struct console *co, char *name, int idx, return -ENODEV; } +static void +pl011_console_write_atomic(struct console *co, struct nbcon_write_context *wctxt) +{ + struct uart_amba_port *uap = amba_ports[co->index]; + unsigned int old_cr = 0; + + if (!nbcon_enter_unsafe(wctxt)) + return; + + clk_enable(uap->clk); + + if (!uap->vendor->always_enabled) { + old_cr = pl011_read(uap, REG_CR); + pl011_write((old_cr & ~UART011_CR_CTSEN) | (UART01x_CR_UARTEN | UART011_CR_TXE), + uap, REG_CR); + } + + if (!uap->console_line_ended) + uart_console_write(&uap->port, "\n", 1, pl011_console_putchar); + uart_console_write(&uap->port, wctxt->outbuf, wctxt->len, pl011_console_putchar); + + while ((pl011_read(uap, REG_FR) ^ uap->vendor->inv_fr) & uap->vendor->fr_busy) + cpu_relax(); + + if (!uap->vendor->always_enabled) + pl011_write(old_cr, uap, REG_CR); + + clk_disable(uap->clk); + + nbcon_exit_unsafe(wctxt); +} + +static void +pl011_console_write_thread(struct console *co, struct nbcon_write_context *wctxt) +{ + struct uart_amba_port *uap = amba_ports[co->index]; + unsigned int old_cr = 0; + + if (!nbcon_enter_unsafe(wctxt)) + return; + + clk_enable(uap->clk); + + if (!uap->vendor->always_enabled) { + old_cr = pl011_read(uap, REG_CR); + pl011_write((old_cr & ~UART011_CR_CTSEN) | (UART01x_CR_UARTEN | UART011_CR_TXE), + uap, REG_CR); + } + + if (nbcon_exit_unsafe(wctxt)) { + int i; + unsigned int len = READ_ONCE(wctxt->len); + + for (i = 0; i < len; i++) { + if (!nbcon_enter_unsafe(wctxt)) + break; + uart_console_write(&uap->port, wctxt->outbuf + i, 1, pl011_console_putchar); + if (!nbcon_exit_unsafe(wctxt)) + break; + } + } + + while (!nbcon_enter_unsafe(wctxt)) + nbcon_reacquire_nobuf(wctxt); + + while ((pl011_read(uap, REG_FR) ^ uap->vendor->inv_fr) & uap->vendor->fr_busy) + cpu_relax(); + + if (!uap->vendor->always_enabled) + pl011_write(old_cr, uap, REG_CR); + + clk_disable(uap->clk); + + nbcon_exit_unsafe(wctxt); +} + +static void +pl011_console_device_lock(struct console *co, unsigned long *flags) +{ + __uart_port_lock_irqsave(&amba_ports[co->index]->port, flags); +} + +static void +pl011_console_device_unlock(struct console *co, unsigned long flags) +{ + __uart_port_unlock_irqrestore(&amba_ports[co->index]->port, flags); +} + +static void +pl011_console_switch_to_nbcon(struct console *co) +{ + co->write = NULL; + co->write_atomic = pl011_console_write_atomic; + co->write_thread = pl011_console_write_thread; + co->device_lock = pl011_console_device_lock; + co->device_unlock = pl011_console_device_unlock; + co->flags = CON_PRINTBUFFER | CON_ANYTIME | CON_NBCON; + pr_info("Serial: switched to nbcon\n"); +} + static struct uart_driver amba_reg; static struct console amba_console = { .name = "ttyAMA", @@ -2737,6 +2846,10 @@ static int pl011_register_port(struct uart_amba_port *uap) pl011_write(0xffff, uap, REG_ICR); if (!amba_reg.state) { + /* Replaces the console descriptor if NBCON is selected. */ + if (amba_reg.cons && use_nbcon) + pl011_console_switch_to_nbcon(amba_reg.cons); + ret = uart_register_driver(&amba_reg); if (ret < 0) { dev_err(uap->port.dev,