From nobody Tue Dec 2 00:26:10 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 2FD9931DDB7; Tue, 25 Nov 2025 15:29:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764084583; cv=none; b=PZmDwHLoG5DJ3/C0Sw9bE+FF8v5W245VBVUNSX8Qhb5+ZH3r3cRi0wP6KMZuYSRKAasTSNEE6XWm9GRnuyb2CDVFSFcpj8NL3atyu0LMyKiK8DjIG2a7AIrH09QzMSYlZ9uln3xuKuT06EVV4y4IfV0dl33ug1vapc3Xm1YXd1o= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764084583; c=relaxed/simple; bh=1Cdu7ryGjoUN+5a4Wzhe92hchlY8H7WA2ItzM1ycKQE=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=sfyDWlnXuIwMxp74AEgzOMd7XjlXTYbzeMd6vftde4yV7WIztBkvF7g0/X2wniCO0T+WXUXxFtu9sHZ9vrlvw8Ksmdl2A5JPHyWJ/cw9IBvulj+VuJoH4z8MZXul55UCWJdoreRBOtOMxHNu66t24Mgp6juo9tfD1HySkrveWbs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OioOU/D6; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="OioOU/D6" Received: by smtp.kernel.org (Postfix) with ESMTPS id BCBABC116B1; Tue, 25 Nov 2025 15:29:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764084582; bh=1Cdu7ryGjoUN+5a4Wzhe92hchlY8H7WA2ItzM1ycKQE=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=OioOU/D6NTKX3fBJ1pcXYDm3BFbJTW4wbYYSfTvWK6zN/xrZOpkJb2dUrkBzJpxnN tQGJ8fwgkNLhalKknw4NDsc7O51Y6F5AC5qXX5OwOitMlJ6XBfWLGF0JjLvFVHk7mT CLYIHLpkgF22M9n3eeE0BeMIKBmfco6vQNMoZJDgyGwbhkxmSBsbBVpWnojWYY8Kn6 LT8Gwq8COWXQGT3Lr3XUvqdXSJNwFO4Zujm9V7pOo2P5q471DlyrnQrN5QodDh5ODJ sCYCSlHmP+OOsJUBpRCrwREAVUalpJ0IE8W87WY6R9wbwKedhl+FynGnH5FYo2u6CG g2S9fPuoioMcw== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id A9E99D0E6FB; Tue, 25 Nov 2025 15:29:42 +0000 (UTC) From: Petri Karhula via B4 Relay Date: Tue, 25 Nov 2025 15:29:39 +0000 Subject: [PATCH v3 1/2] backlight: Add Congatec Board Controller (CGBC) backlight support Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20251125-cgbc-backlight-v3-1-18ae42689411@novatron.fi> References: <20251125-cgbc-backlight-v3-0-18ae42689411@novatron.fi> In-Reply-To: <20251125-cgbc-backlight-v3-0-18ae42689411@novatron.fi> To: Thomas Richard , Lee Jones , Daniel Thompson , Jingoo Han , Helge Deller Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, Petri Karhula X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1764084581; l=7505; i=petri.karhula@novatron.fi; s=20251118; h=from:subject:message-id; bh=ghGMJcHgpx+ghbOHu8OLsg2XcnA/p+jziev4WnLflSE=; b=raeafupZUvkRlSZ26aR1Z1U5ig+nkY8E8uOkUyDiNE6srxgh+A5eRA7GmsOk+WmILImNNh5Fr lb38obDK9v+AIBA/HcR6tZ2WSPlN/LoZ+1N9T7WJD9T45uhsLZqQKDZ X-Developer-Key: i=petri.karhula@novatron.fi; a=ed25519; pk=LRYJ99jPPsHJwdJEPkqlmzAMqo6oyw7I421aHEfDp7o= X-Endpoint-Received: by B4 Relay for petri.karhula@novatron.fi/20251118 with auth_id=567 X-Original-From: Petri Karhula Reply-To: petri.karhula@novatron.fi From: Petri Karhula This driver provides backlight brightness control through the Linux backlight subsystem. It communicates with the board controller to adjust LCD backlight using PWM signals. Communication is done through Congatec Board Controller core driver. Signed-off-by: Petri Karhula --- drivers/video/backlight/Kconfig | 11 +++ drivers/video/backlight/Makefile | 1 + drivers/video/backlight/cgbc_bl.c | 177 ++++++++++++++++++++++++++++++++++= ++++ 3 files changed, 189 insertions(+) diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kcon= fig index d9374d208cee..702f3b8ed036 100644 --- a/drivers/video/backlight/Kconfig +++ b/drivers/video/backlight/Kconfig @@ -249,6 +249,17 @@ config BACKLIGHT_PWM If you have a LCD backlight adjustable by PWM, say Y to enable this driver. =20 +config BACKLIGHT_CGBC + tristate "Congatec Board Controller (CGBC) backlight support" + depends on MFD_CGBC && X86 + help + Say Y here to enable support for LCD backlight control on Congatec + x86-based boards via the CGBC (Congatec Board Controller). + + This driver provides backlight brightness control through the Linux + backlight subsystem. It communicates with the board controller to + adjust LCD backlight using PWM signals. + config BACKLIGHT_DA903X tristate "Backlight Driver for DA9030/DA9034 using WLED" depends on PMIC_DA903X diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Mak= efile index dfbb169bf6ea..0169fd8873ed 100644 --- a/drivers/video/backlight/Makefile +++ b/drivers/video/backlight/Makefile @@ -27,6 +27,7 @@ obj-$(CONFIG_BACKLIGHT_APPLE_DWI) +=3D apple_dwi_bl.o obj-$(CONFIG_BACKLIGHT_AS3711) +=3D as3711_bl.o obj-$(CONFIG_BACKLIGHT_BD6107) +=3D bd6107.o obj-$(CONFIG_BACKLIGHT_CLASS_DEVICE) +=3D backlight.o +obj-$(CONFIG_BACKLIGHT_CGBC) +=3D cgbc_bl.o obj-$(CONFIG_BACKLIGHT_DA903X) +=3D da903x_bl.o obj-$(CONFIG_BACKLIGHT_DA9052) +=3D da9052_bl.o obj-$(CONFIG_BACKLIGHT_EP93XX) +=3D ep93xx_bl.o diff --git a/drivers/video/backlight/cgbc_bl.c b/drivers/video/backlight/cg= bc_bl.c new file mode 100644 index 000000000000..73ee6d440bcd --- /dev/null +++ b/drivers/video/backlight/cgbc_bl.c @@ -0,0 +1,177 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Congatec Board Controller (CGBC) Backlight Driver + * + * This driver provides backlight control for LCD displays connected to + * Congatec boards via the CGBC (Congatec Board Controller). It integrates + * with the Linux backlight subsystem and communicates with hardware throu= gh + * the cgbc-core module. + * + * Copyright (C) 2025 Novatron Oy + * + * Author: Petri Karhula + */ + +#include +#include +#include +#include +#include +#include + +#define BLT_PWM_DUTY_MASK GENMASK(6, 0) + +/* CGBC command for PWM brightness control*/ +#define CGBC_CMD_BLT0_PWM 0x75 + +#define CGBC_BL_MAX_BRIGHTNESS 100 + +/** + * CGBC backlight driver data + * @dev: Pointer to the platform device + * @cgbc: Pointer to the parent CGBC device data + * @current_brightness: Current brightness level (0-100) + */ +struct cgbc_bl_data { + struct device *dev; + struct cgbc_device_data *cgbc; + unsigned int current_brightness; +}; + +static int cgbc_bl_update_status(struct backlight_device *bl) +{ + struct cgbc_bl_data *bl_data =3D bl_get_data(bl); + u8 cmd_buf[4] =3D { CGBC_CMD_BLT0_PWM }; + u8 reply_buf[3]; + u8 brightness; + int ret; + + brightness =3D backlight_get_brightness(bl); + + if (brightness !=3D bl_data->current_brightness) { + /* Read the current values */ + ret =3D cgbc_command(bl_data->cgbc, cmd_buf, sizeof(cmd_buf), reply_buf, + sizeof(reply_buf), NULL); + if (ret < 0) { + dev_err(bl_data->dev, "Failed to read PWM settings: %d\n", ret); + return ret; + } + + /* + * Prepare command buffer for writing new settings. Only 2nd byte is cha= nged + * to set new brightness (PWM duty cycle %). Other values (polarity, fre= quency) + * are preserved from the read values. + */ + cmd_buf[1] =3D (reply_buf[0] & ~BLT_PWM_DUTY_MASK) | + FIELD_PREP(BLT_PWM_DUTY_MASK, brightness); + cmd_buf[2] =3D reply_buf[1]; + cmd_buf[3] =3D reply_buf[2]; + + ret =3D cgbc_command(bl_data->cgbc, cmd_buf, sizeof(cmd_buf), reply_buf, + sizeof(reply_buf), NULL); + if (ret < 0) { + dev_err(bl_data->dev, "Failed to set brightness: %d\n", ret); + return ret; + } + + bl_data->current_brightness =3D reply_buf[0] & BLT_PWM_DUTY_MASK; + + /* Verify the setting was applied correctly */ + if (bl_data->current_brightness !=3D brightness) { + dev_err(bl_data->dev, + "Brightness setting verification failed\n"); + return -EIO; + } + } + + return 0; +} + +static int cgbc_bl_get_brightness(struct backlight_device *bl) +{ + struct cgbc_bl_data *bl_data =3D bl_get_data(bl); + u8 cmd_buf[4] =3D { CGBC_CMD_BLT0_PWM }; + u8 reply_buf[3]; + int ret; + + ret =3D cgbc_command(bl_data->cgbc, cmd_buf, sizeof(cmd_buf), reply_buf, + sizeof(reply_buf), NULL); + + if (ret < 0) { + dev_err(bl_data->dev, "Failed to read brightness: %d\n", ret); + return ret; + } + + /* + * Only return PWM duty factor percentage, + * ignore polarity inversion bit (bit 7) + */ + bl_data->current_brightness =3D FIELD_GET(BLT_PWM_DUTY_MASK, reply_buf[0]= ); + + return bl_data->current_brightness; +} + +static const struct backlight_ops cgbc_bl_ops =3D { + .options =3D BL_CORE_SUSPENDRESUME, + .update_status =3D cgbc_bl_update_status, + .get_brightness =3D cgbc_bl_get_brightness, +}; + +static int cgbc_bl_probe(struct platform_device *pdev) +{ + struct cgbc_device_data *cgbc =3D dev_get_drvdata(pdev->dev.parent); + struct backlight_properties props =3D { }; + u8 cmd_buf[4] =3D { CGBC_CMD_BLT0_PWM }; + struct backlight_device *bl_dev; + struct cgbc_bl_data *bl_data; + u8 reply_buf[3]; + int ret; + + bl_data =3D devm_kzalloc(&pdev->dev, sizeof(*bl_data), GFP_KERNEL); + if (!bl_data) + return -ENOMEM; + + bl_data->dev =3D &pdev->dev; + bl_data->cgbc =3D cgbc; + + ret =3D cgbc_command(bl_data->cgbc, cmd_buf, sizeof(cmd_buf), reply_buf, + sizeof(reply_buf), NULL); + if (ret < 0) + return dev_err_probe(&pdev->dev, ret, + "Failed to read initial brightness\n"); + + /* + * Get only PWM duty factor percentage, + * ignore polarity inversion bit (bit 7) + */ + bl_data->current_brightness =3D FIELD_GET(BLT_PWM_DUTY_MASK, reply_buf[0]= ); + + props.type =3D BACKLIGHT_PLATFORM; + props.max_brightness =3D CGBC_BL_MAX_BRIGHTNESS; + props.brightness =3D bl_data->current_brightness; + + bl_dev =3D devm_backlight_device_register(&pdev->dev, "cgbc-backlight", + &pdev->dev, bl_data, + &cgbc_bl_ops, &props); + if (IS_ERR(bl_dev)) + return dev_err_probe(&pdev->dev, PTR_ERR(bl_dev), + "Failed to register backlight device\n"); + + platform_set_drvdata(pdev, bl_data); + + return 0; +} + +static struct platform_driver cgbc_bl_driver =3D { + .driver =3D { + .name =3D "cgbc-backlight", + }, + .probe =3D cgbc_bl_probe, +}; + +module_platform_driver(cgbc_bl_driver); + +MODULE_AUTHOR("Petri Karhula "); +MODULE_DESCRIPTION("Congatec Board Controller (CGBC) Backlight Driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:cgbc-backlight"); --=20 2.34.1