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smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qPyZgo07; 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="qPyZgo07" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61BD8C4CEDD; Wed, 8 Jan 2025 10:52:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1736333564; bh=BUkcEIZO72zG0bmSzzrHuBtmboN5338uqDoQVUVBraU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qPyZgo075e0ivgTjrIrZ1ezJszqrsrblWv3plRZKkE7lDx5MBcl6MxAlahkjMIsFN BZQdSDHwj/yC1EKNXJhsqVGT978YcXPP0IJ5UlgxsTSm28EgPXjEKQv68E6R78SOVc 5izTa3NcOTbULgiLpQXfBqMbOTYiw1nhQw+XpfO92YbBHsqubxE1GEppQ1yJiWACCd GSHsQ+P47ZH3cMpBRMFrwjDg1O9+Y2XCtri32i3MEsjBJYHlk6bhasiKf1h/VytRra KOSBaY6mWyPa6ptojEl/+dolGsARtVPVcvPjWp49IG7HnRBTdUOx43gTcDcA8NIgl4 RGG7hTZqWBRzg== Date: Wed, 8 Jan 2025 10:52:38 +0000 From: Daniel Thompson To: Nick Chan Cc: Lee Jones , Jingoo Han , Pavel Machek , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Helge Deller , Hector Martin , Sven Peter , Alyssa Rosenzweig , dri-devel@lists.freedesktop.org, linux-leds@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org, asahi@lists.linux.dev, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v4 2/3] backlight: dwi_bl: Add Apple DWI backlight driver Message-ID: References: <20241211113512.19009-1-towinchenmi@gmail.com> <20241211113512.19009-3-towinchenmi@gmail.com> Precedence: bulk X-Mailing-List: linux-leds@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241211113512.19009-3-towinchenmi@gmail.com> On Wed, Dec 11, 2024 at 07:34:38PM +0800, Nick Chan wrote: > Add driver for backlight controllers attached via Apple DWI 2-wire > interface, which is found on some Apple iPhones, iPads and iPod touches > with a LCD display. > > Although there is an existing apple_bl driver, it is for backlight > controllers on Intel Macs attached via PCI, which is completely different > from the Samsung-derived DWI block. > > Signed-off-by: Nick Chan > --- > drivers/video/backlight/Kconfig | 12 +++ > drivers/video/backlight/Makefile | 1 + > drivers/video/backlight/dwi_bl.c | 122 +++++++++++++++++++++++++++++++ I'd rather this was called apple_dwi_bl.c to match that config options, etc. > diff --git a/drivers/video/backlight/dwi_bl.c b/drivers/video/backlight/dwi_bl.c > new file mode 100644 > index 000000000000..59e5cad0fbd8 > --- /dev/null > +++ b/drivers/video/backlight/dwi_bl.c > @@ -0,0 +1,122 @@ > +// SPDX-License-Identifier: GPL-2.0 OR MIT > +/* > + * Driver for backlight controllers attached via Apple DWI 2-wire interface > + * > + * Copyright (c) 2024 Nick Chan > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > + > +#define DWI_BL_CTL 0x0 > +#define DWI_BL_CTL_SEND1 BIT(0) > +#define DWI_BL_CTL_SEND2 BIT(4) > +#define DWI_BL_CTL_SEND3 BIT(5) > +#define DWI_BL_CTL_LE_DATA BIT(6) > +/* Only used on Apple A9 and later */ > +#define DWI_BL_CTL_SEND4 BIT(12) > + > +#define DWI_BL_CMD 0x4 > +#define DWI_BL_CMD_TYPE GENMASK(31, 28) > +#define DWI_BL_CMD_TYPE_SET_BRIGHTNESS 0xa > +#define DWI_BL_CMD_DATA GENMASK(10, 0) > + > +#define DWI_BL_CTL_SEND (DWI_BL_CTL_SEND1 | \ > + DWI_BL_CTL_SEND2 | \ > + DWI_BL_CTL_SEND3 | \ > + DWI_BL_CTL_LE_DATA | \ > + DWI_BL_CTL_SEND4) > + > +#define DWI_BL_MAX_BRIGHTNESS 2047 > + > +struct apple_dwi_bl { > + void __iomem *base; > +}; > + > +static int dwi_bl_update_status(struct backlight_device *bl) > +{ > + struct apple_dwi_bl *dwi_bl = bl_get_data(bl); > + > + int brightness = backlight_get_brightness(bl); > + > + u32 cmd = 0; > + > + cmd |= FIELD_PREP(DWI_BL_CMD_DATA, brightness); > + cmd |= FIELD_PREP(DWI_BL_CMD_TYPE, DWI_BL_CMD_TYPE_SET_BRIGHTNESS); > + > + writel(cmd, dwi_bl->base + DWI_BL_CMD); > + writel(DWI_BL_CTL_SEND, dwi_bl->base + DWI_BL_CTL); > + > + return 0; > +} > + > +static int dwi_bl_get_brightness(struct backlight_device *bl) > +{ > + struct apple_dwi_bl *dwi_bl = bl_get_data(bl); > + > + u32 cmd = readl(dwi_bl->base + DWI_BL_CMD); > + > + return FIELD_GET(DWI_BL_CMD_DATA, cmd); > +} > + > +static const struct backlight_ops dwi_bl_ops = { > + .options = BL_CORE_SUSPENDRESUME, > + .get_brightness = dwi_bl_get_brightness, > + .update_status = dwi_bl_update_status > +}; > + > +static int dwi_bl_probe(struct platform_device *dev) > +{ > + struct apple_dwi_bl *dwi_bl; > + struct backlight_device *bl; > + struct backlight_properties props; > + struct resource *res; > + > + dwi_bl = devm_kzalloc(&dev->dev, sizeof(*dwi_bl), GFP_KERNEL); > + if (!dwi_bl) > + return -ENOMEM; > + > + dwi_bl->base = devm_platform_get_and_ioremap_resource(dev, 0, &res); > + if (IS_ERR(dwi_bl->base)) > + return PTR_ERR(dwi_bl->base); > + > + memset(&props, 0, sizeof(struct backlight_properties)); > + props.type = BACKLIGHT_RAW; > + props.max_brightness = DWI_BL_MAX_BRIGHTNESS; There should be something to indicate whether the backlight controls are linear or logarithmic here. > +static struct platform_driver dwi_bl_driver = { > + .driver = { > + .name = "dwi-bl", Again, I'd rather see apple here too (although, to be clear, I'm perfectly happy with all the static functions and variables being prefixed only with dwi_bl). Daniel.