From patchwork Fri Apr 5 12:05:52 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bastien Curutchet X-Patchwork-Id: 786695 Received: from relay3-d.mail.gandi.net (relay3-d.mail.gandi.net [217.70.183.195]) (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 7146416ABCE; Fri, 5 Apr 2024 12:06:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.183.195 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712318766; cv=none; b=KeYlA2+yU8P3QNBnxvFxQfv/kNpz+eezSB6u+4RV5YbJS3NbOc4vwVeWgv5IiIgb6ky3jfymZ0Xll0IqO36FdfaQ5kl/A+nqpeaauE7wWkn3CBqeDkR0KIVZ0jWEPPbPKHhFogIVB38050ycbfF5mwaGQkfJxYqSEbRliINvjz4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712318766; c=relaxed/simple; bh=3SOawKf7ShxwVuliq6PEQpm/4ZVoz/cacxEBlBkgzko=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=tPCMyYBVbbE+/aw9c6OutP+ep15AL3s9TRXsyujf23pEIQr9aSfWKC5EwARNSB+H26SydkLbbuJHbbOvAThQod4bgjTCuboTx5WsDx60+Pvx1nusMzWlLXmSmoo4HTxqUSccuMmM9rb6aUVNuz3IWf4kMzn4xSKJ8EnCfqsOGYA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=jUV6/BWI; arc=none smtp.client-ip=217.70.183.195 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="jUV6/BWI" Received: by mail.gandi.net (Postfix) with ESMTPA id CBB5C60009; Fri, 5 Apr 2024 12:05:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1712318755; 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; bh=dLx+yQeXl9X7vSpjKyi2n2Z3bqsnNuxCnQzI/RO3bx4=; b=jUV6/BWIzPQt0r3RaYyWkUQFqzRMNk8l0YxD4DVH2/yWPbRsNZ6Bw6J2VKFlY+h96jrT5a ns72dPJFsEjb4hK4iauxpCr9U2/n3infaHmdtGnNjqBzOmT3hEU8w9V/u9cG80nt2OzWBi sl1HwQnsAKA/kw7w35QYh4xx07m7di2Xi16zneYKgE2FvtXTWMX8v+TmCLhwuujZc4qSMH mkudrvXCrgiYVb9ZsQ7//jKwZMmFdBv97JtwBHrMtRzTEXGDC69h2vaY9FmbI1Y0MQbGwd H5oknzmopj66WdEHTcuMNz9rs4OR5L+vkx8Ep7+KC44bCuoL+cvwMn1V9ic3BA== From: Bastien Curutchet To: bastien.curutchet@bootlin.com, Greg Kroah-Hartman , Jiri Slaby Cc: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, Thomas Petazzoni , herve.codina@bootlin.com, christophercordahi@nanometrics.ca Subject: [PATCH v2 1/1] serial: 8250_of: Add clock_notifier Date: Fri, 5 Apr 2024 14:05:52 +0200 Message-ID: <20240405120552.35991-1-bastien.curutchet@bootlin.com> X-Mailer: git-send-email 2.44.0 Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-GND-Sasl: bastien.curutchet@bootlin.com The UART's input clock rate can change at runtime but this is not handled by the driver. Add a clock_notifier callback that updates the divisors when the input clock is updated. The serial8250_update_uartclk() is used to do so. PRE_RATE_CHANGE and ABORT_RATE_CHANGE notifications are ignored, only the POST_RATE_CHANGE is used. Not using PRE_RATE_CHANGE notification can result in a few corrupted bytes during frequency transitions but, IMHO, it can be acceptable in many use cases. It has been tested on a DAVINCI/OMAP-L138 processor. Signed-off-by: Bastien Curutchet --- Change log v1 -> v2: * Add details in commit log * Drop alphabetic order in #include * Drop a useless check in notifier callback v1 : https://lore.kernel.org/all/20240404074450.42708-1-bastien.curutchet@bootlin.com/ drivers/tty/serial/8250/8250_of.c | 37 +++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c index 5d1dd992d8fb..e14f47ef1172 100644 --- a/drivers/tty/serial/8250/8250_of.c +++ b/drivers/tty/serial/8250/8250_of.c @@ -18,6 +18,7 @@ #include #include #include +#include #include "8250.h" @@ -26,6 +27,7 @@ struct of_serial_info { struct reset_control *rst; int type; int line; + struct notifier_block clk_notifier; }; /* Nuvoton NPCM timeout register */ @@ -58,6 +60,26 @@ static int npcm_setup(struct uart_port *port) return 0; } +static inline struct of_serial_info *clk_nb_to_info(struct notifier_block *nb) +{ + return container_of(nb, struct of_serial_info, clk_notifier); +} + +static int of_platform_serial_clk_notifier_cb(struct notifier_block *nb, unsigned long event, + void *data) +{ + struct of_serial_info *info = clk_nb_to_info(nb); + struct uart_8250_port *port8250 = serial8250_get_port(info->line); + struct clk_notifier_data *ndata = data; + + if (event == POST_RATE_CHANGE) { + serial8250_update_uartclk(&port8250->port, ndata->new_rate); + return NOTIFY_OK; + } + + return NOTIFY_DONE; +} + /* * Fill a struct uart_port for a given device node */ @@ -218,7 +240,19 @@ static int of_platform_serial_probe(struct platform_device *ofdev) info->type = port_type; info->line = ret; platform_set_drvdata(ofdev, info); + + if (info->clk) { + info->clk_notifier.notifier_call = of_platform_serial_clk_notifier_cb; + ret = clk_notifier_register(info->clk, &info->clk_notifier); + if (ret) { + dev_err_probe(port8250.port.dev, ret, "Failed to set the clock notifier\n"); + goto err_unregister; + } + } + return 0; +err_unregister: + serial8250_unregister_port(info->line); err_dispose: pm_runtime_put_sync(&ofdev->dev); pm_runtime_disable(&ofdev->dev); @@ -234,6 +268,9 @@ static void of_platform_serial_remove(struct platform_device *ofdev) { struct of_serial_info *info = platform_get_drvdata(ofdev); + if (info->clk) + clk_notifier_unregister(info->clk, &info->clk_notifier); + serial8250_unregister_port(info->line); reset_control_assert(info->rst);