From patchwork Wed Apr 3 15:22:52 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Esben Haabendal X-Patchwork-Id: 785687 Received: from www530.your-server.de (www530.your-server.de [188.40.30.78]) (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 DC3CA149DFD for ; Wed, 3 Apr 2024 15:22:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=188.40.30.78 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712157777; cv=none; b=JkOvip2YsACAHxq6ewvWlVW1d3Xjevls8SfM2D4mc5BUA3FVUqw+z8UtoPC+bzIt+DirYPJJKYpF90l1M6yLmSbPukq7vXcXHtAJHe+sT32a/GjnMNNIP4PeAe+MLTwvdV5zQXgZ5sh3CTfWZMzUnEbOkXyWnhTzYxnJGBty1ng= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712157777; c=relaxed/simple; bh=SxpR1u4qw4FLXORsNfelmog7zJByFeg7BE3dEP4Jo3Q=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=llQxMdkV5H/Gh7qhELxz5GMBGT/ZgesB9Hq21ZXNeCpwKoc2ue7cNNMizmcht/uNq5DWpOePGQ7C/f9JAmTn+kpJ41rQ+VtMWHV1GDaX/ckEMyi7ar0lePGBtWAw0jrdi/wRGaB7+eqJcwFSHoZg8pqE/nky8xTJmofaluKr9Wk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=geanix.com; spf=pass smtp.mailfrom=geanix.com; dkim=pass (2048-bit key) header.d=geanix.com header.i=@geanix.com header.b=JiWknZFA; arc=none smtp.client-ip=188.40.30.78 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=geanix.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=geanix.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=geanix.com header.i=@geanix.com header.b="JiWknZFA" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=geanix.com; s=default2211; h=Content-Transfer-Encoding:MIME-Version:References: In-Reply-To:Message-ID:Date:Subject:To:From:Sender:Reply-To:Cc:Content-Type: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID; bh=pYAA+BILTgcm8agMd1DYp0oRUZ3ZGpnHgkGBWLwmfmA=; b=JiWknZFAc4U/RPZ6p9KRb7fyHB ysgDdxpZ2ESGmpdYFVUwOMjF1sSE4rvHNbaVXMFzqQGLzw7sBVaRV/mBvB5FI9ebztpQsysPTD7WK DdiN/IIkXRQfixlBGkHh4DUL6RdvzB9tm1OIWdvCvb+kmEk8/AxYeO6Dc0k9ZgqWdSOSAiYzxkok2 RewETgURoccl+fBfI6lmZ3AUJEAsnMYkdCva2JpaBTkpIWfXehlWimcNj5o2bPCe9+04yy7CYNLRd y+PpbV1T2gHedg7ryMUTIFijmaE1ykpQxiJL1PcP9Roe1Qq1BX9gyHRek7uBOUlHDGw2ypKPGrp9g r5dZcdqw==; Received: from sslproxy05.your-server.de ([78.46.172.2]) by www530.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1rs2Rv-000Hwh-Kn; Wed, 03 Apr 2024 17:22:51 +0200 Received: from [185.17.218.86] (helo=localhost) by sslproxy05.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1rs2Rv-004jtg-1J; Wed, 03 Apr 2024 17:22:51 +0200 From: Esben Haabendal To: linux-rt-users@vger.kernel.org, John Ogness Subject: [RFC PATCH 1/2] serial: imx: Avoid busy polling for transmitter to become empty Date: Wed, 3 Apr 2024 17:22:52 +0200 Message-ID: <9895c8f9553523d158f47a9718bd24f22dbe0455.1712156846.git.esben@geanix.com> X-Mailer: git-send-email 2.44.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-rt-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Authenticated-Sender: esben@geanix.com X-Virus-Scanned: Clear (ClamAV 0.103.10/27234/Wed Apr 3 10:25:27 2024) Busy polling with readl() is a rather harsh way to wait for a potentially long time. While there, introduce a 10 ms timeout on this waiting, similar to what many other serial drivers do. Signed-off-by: Esben Haabendal --- drivers/tty/serial/imx.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 54b760d845c0..16661827277e 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -26,6 +26,7 @@ #include #include #include +#include #include #include @@ -1995,7 +1996,7 @@ imx_uart_console_write(struct console *co, const char *s, unsigned int count) struct imx_port *sport = imx_uart_ports[co->index]; struct imx_port_ucrs old_ucr; unsigned long flags; - unsigned int ucr1; + unsigned int ucr1, usr2; int locked = 1; if (sport->port.sysrq) @@ -2026,8 +2027,8 @@ imx_uart_console_write(struct console *co, const char *s, unsigned int count) * Finally, wait for transmitter to become empty * and restore UCR1/2/3 */ - while (!(imx_uart_readl(sport, USR2) & USR2_TXDC)); - + read_poll_timeout_atomic(imx_uart_readl, usr2, usr2 & USR2_TXDC, + 1, 10000, false, sport, USR2); imx_uart_ucrs_restore(sport, &old_ucr); if (locked) From patchwork Wed Apr 3 15:22:53 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Esben Haabendal X-Patchwork-Id: 787355 Received: from www530.your-server.de (www530.your-server.de [188.40.30.78]) (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 429CD14A4CE for ; Wed, 3 Apr 2024 15:22:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=188.40.30.78 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712157777; cv=none; b=EKEj1hihCVtJIzy8fkaZIhIgMYLunlOP8TQoe2m3IYSw2dKdtJ76/I80EaRIJAoWZdgcgCe8HPbkBdlgs/u/GJ4r2hWxKvrQ69y4mgY8sseXMsJOgag0LAlNuR5NvaQZgfy2pHn1uIXIHk2NHlWORFXADEfnba9dayeG/zK1kHk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712157777; c=relaxed/simple; bh=E/YW0lYQkq32hi/6tLdxY4zD3i4BzL3bLXi2HNlkB3g=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WXmWElc6QouWKkNl8397qgv0tLAbSCjPXtm8e09gkEcm+mrb8Myt3UFVBbkHuURvnFjBUfgDxH9XpY5p8FjVzUfFEHzUCgSbDRpnvODOSWyRE3Tnf29ijsiweLhQJ5/T8esHJ+s5Mxf08TflL2L+qg/HFLMBO7mqcNJCgVM2akY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=geanix.com; spf=pass smtp.mailfrom=geanix.com; dkim=pass (2048-bit key) header.d=geanix.com header.i=@geanix.com header.b=CCFUxh7m; arc=none smtp.client-ip=188.40.30.78 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=geanix.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=geanix.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=geanix.com header.i=@geanix.com header.b="CCFUxh7m" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=geanix.com; s=default2211; h=Content-Transfer-Encoding:MIME-Version:References: In-Reply-To:Message-ID:Date:Subject:To:From:Sender:Reply-To:Cc:Content-Type: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID; bh=+mOrOqvyV/OGQLcHRueApbE5Rwa5KJKgYDdT2tk0Q+Q=; b=CCFUxh7mvEdEokBiSevV7gB+KI ruQGzlTN3C8470qEO9mvX9lYUhWGfxqAwXvjqGF2YPkskdSDQl2ykqSXACx9ZjejNPynOKqIByC1q vIugl6aRfsXMvjSHvzxWo3T4NDKXzAWDeORF+vE6WXrYVnVx6oUoEE6K8rLFtBkeL9TwiIw2sxQEU 3XWe217VS0h2ZcFWOg0xhAv20LDexVVvh4rwvoK4wS8fxokUCO0LonePYgWhCpbzCfqiqoZlbJtWL 4vr6H527qSMoWZDfiWXL+4I7TiiOnJ692FzqR2zzwG5R2KkBuKxsRdUE47sjqzm3i6J5G5BhoKiJr 8XLfh0zA==; Received: from sslproxy05.your-server.de ([78.46.172.2]) by www530.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1rs2Rw-000Hwq-2F; Wed, 03 Apr 2024 17:22:52 +0200 Received: from [185.17.218.86] (helo=localhost) by sslproxy05.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1rs2Rv-004jvH-2i; Wed, 03 Apr 2024 17:22:51 +0200 From: Esben Haabendal To: linux-rt-users@vger.kernel.org, John Ogness Subject: [RFC PATCH 2/2] serial: imx: Switch to nbcon console Date: Wed, 3 Apr 2024 17:22:53 +0200 Message-ID: <47b4667db579019c292ece5563d74f897c62f046.1712156846.git.esben@geanix.com> X-Mailer: git-send-email 2.44.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-rt-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Authenticated-Sender: esben@geanix.com X-Virus-Scanned: Clear (ClamAV 0.103.10/27234/Wed Apr 3 10:25:27 2024) Implements the necessary callbacks to switch the imx console driver to perform as an nbcon console. Add implementations for the nbcon consoles (write_atomic, write_thread, driver_enter, driver_exit) and add CON_NBCON to the initial flags. The legacy code is kept in order to easily switch back to legacy mode by defining CONFIG_SERIAL_IMX_LEGACY_CONSOLE. Signed-off-by: Esben Haabendal --- drivers/tty/serial/imx.c | 154 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 153 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 16661827277e..7030fa2bcaea 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -230,6 +230,8 @@ struct imx_port { unsigned int saved_reg[10]; bool context_saved; + bool console_newline_needed; + enum imx_tx_state tx_state; struct hrtimer trigger_start_tx; struct hrtimer trigger_stop_tx; @@ -1985,8 +1987,14 @@ static void imx_uart_console_putchar(struct uart_port *port, unsigned char ch) barrier(); imx_uart_writel(sport, ch, URTX0); + + if (ch == '\n') + sport->console_newline_needed = false; + else + sport->console_newline_needed = true; } +#ifdef CONFIG_SERIAL_IMX_LEGACY_CONSOLE /* * Interrupts are disabled on entering */ @@ -2034,6 +2042,140 @@ imx_uart_console_write(struct console *co, const char *s, unsigned int count) if (locked) uart_port_unlock_irqrestore(&sport->port, flags); } +#else +static void imx_uart_console_driver_enter(struct console *co, unsigned long *flags) +{ + struct uart_port *up = &imx_uart_ports[co->index]->port; + + return __uart_port_lock_irqsave(up, flags); +} + +static void imx_uart_console_driver_exit(struct console *co, unsigned long flags) +{ + struct uart_port *up = &imx_uart_ports[co->index]->port; + + return __uart_port_unlock_irqrestore(up, flags); +} + +static bool imx_uart_console_write_atomic(struct console *co, + struct nbcon_write_context *wctxt) +{ + struct imx_port *sport = imx_uart_ports[co->index]; + struct uart_port *port = &sport->port; + struct imx_port_ucrs old_ucr; + unsigned int ucr1, usr2; + + if (!nbcon_enter_unsafe(wctxt)) + return false; + + /* + * First, save UCR1/2/3 and then disable interrupts + */ + imx_uart_ucrs_save(sport, &old_ucr); + ucr1 = old_ucr.ucr1; + + if (imx_uart_is_imx1(sport)) + ucr1 |= IMX1_UCR1_UARTCLKEN; + ucr1 |= UCR1_UARTEN; + ucr1 &= ~(UCR1_TRDYEN | UCR1_RRDYEN | UCR1_RTSDEN); + + imx_uart_writel(sport, ucr1, UCR1); + + imx_uart_writel(sport, old_ucr.ucr2 | UCR2_TXEN, UCR2); + + if (sport->console_newline_needed) + uart_console_write(port, "\n", 1, imx_uart_console_putchar); + uart_console_write(port, wctxt->outbuf, wctxt->len, + imx_uart_console_putchar); + + /* + * Finally, wait for transmitter to become empty + * and restore UCR1/2/3 + */ + read_poll_timeout_atomic(imx_uart_readl, usr2, usr2 & USR2_TXDC, + 1, 10000, false, sport, USR2); + imx_uart_ucrs_restore(sport, &old_ucr); + + /* Success if no handover/takeover. */ + return nbcon_exit_unsafe(wctxt); +} + +static bool imx_uart_console_write_thread(struct console *co, + struct nbcon_write_context *wctxt) +{ + struct imx_port *sport = imx_uart_ports[co->index]; + struct uart_port *port = &sport->port; + struct imx_port_ucrs old_ucr; + unsigned int ucr1, usr2; + bool done = false; + + if (!nbcon_enter_unsafe(wctxt)) + return false; + + /* + * First, save UCR1/2/3 and then disable interrupts + */ + imx_uart_ucrs_save(sport, &old_ucr); + ucr1 = old_ucr.ucr1; + + if (imx_uart_is_imx1(sport)) + ucr1 |= IMX1_UCR1_UARTCLKEN; + ucr1 |= UCR1_UARTEN; + ucr1 &= ~(UCR1_TRDYEN | UCR1_RRDYEN | UCR1_RTSDEN); + + imx_uart_writel(sport, ucr1, UCR1); + + imx_uart_writel(sport, old_ucr.ucr2 | UCR2_TXEN, UCR2); + + if (nbcon_exit_unsafe(wctxt)) { + int len = READ_ONCE(wctxt->len); + int i; + + /* + * Write out the message. Toggle unsafe for each byte in order + * to give another (higher priority) context the opportunity + * for a friendly takeover. If such a takeover occurs, this + * context must reacquire ownership in order to perform final + * actions (such as re-enabling the interrupts). + * + * IMPORTANT: wctxt->outbuf and wctxt->len are no longer valid + * after a reacquire so writing the message must be + * aborted. + */ + for (i = 0; i < len; i++) { + if (!nbcon_enter_unsafe(wctxt)) { + nbcon_reacquire(wctxt); + break; + } + + uart_console_write(port, wctxt->outbuf + i, 1, + imx_uart_console_putchar); + + if (!nbcon_exit_unsafe(wctxt)) { + nbcon_reacquire(wctxt); + break; + } + } + done = (i == len); + } else { + nbcon_reacquire(wctxt); + } + + while (!nbcon_enter_unsafe(wctxt)) + nbcon_reacquire(wctxt); + + /* + * Finally, wait for transmitter to become empty + * and restore UCR1/2/3 + */ + read_poll_timeout(imx_uart_readl, usr2, usr2 & USR2_TXDC, + 1, 10000, false, sport, USR2); + imx_uart_ucrs_restore(sport, &old_ucr); + + /* Success if no handover/takeover and message fully printed. */ + return (nbcon_exit_unsafe(wctxt) && done); +} +#endif /* CONFIG_SERIAL_IMX_LEGACY_CONSOLE */ /* * If the port was already initialised (eg, by a boot loader), @@ -2124,6 +2266,8 @@ imx_uart_console_setup(struct console *co, char *options) if (retval) goto error_console; + sport->console_newline_needed = false; + if (options) uart_parse_options(options, &baud, &parity, &bits, &flow); else @@ -2160,11 +2304,19 @@ imx_uart_console_exit(struct console *co) static struct uart_driver imx_uart_uart_driver; static struct console imx_uart_console = { .name = DEV_NAME, +#ifdef CONFIG_SERIAL_IMX_LEGACY_CONSOLE .write = imx_uart_console_write, + .flags = CON_PRINTBUFFER, +#else + .write_atomic = imx_uart_console_write_atomic, + .write_thread = imx_uart_console_write_thread, + .driver_enter = imx_uart_console_driver_enter, + .driver_exit = imx_uart_console_driver_exit, + .flags = CON_PRINTBUFFER | CON_NBCON, +#endif .device = uart_console_device, .setup = imx_uart_console_setup, .exit = imx_uart_console_exit, - .flags = CON_PRINTBUFFER, .index = -1, .data = &imx_uart_uart_driver, };