From mboxrd@z Thu Jan 1 00:00:00 1970 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 86A264690; Sun, 9 Mar 2025 09:15:58 +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=1741511758; cv=none; b=Lt3QyewDp7y2L8yTUQ5guB6vjBknCJLL1NlQ+CRHGDoXgrhr15CtnjP5yYk01q09GlbhP8vG/+WK3UAEQZjH+8B2Wr+P6UFp+w05pq6g3v14PYVna2ezwbRQ8j/QHBoFl4ihG1FPEEzoBW8nNxlvnGwLY/NvxiVlTNjs+j1YKkY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741511758; c=relaxed/simple; bh=K3xV6qADVt+GGw/9neE6bZZlut/7sckI+B8ywCNR4bI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=BEF6QZgdfYL63yj7O9jizlmd/+BjU1BW9fNgBY524xy8bxb/gW6E3XHx4bfZZB/pA4ZrGc/iur2u2cZe8+JSWZz1OszDM1hhIApk58jDjB0xMR1bkZ+7isWdPmTWsUnUBcKx44KUAm5dMLNvZFV7Ov+hbgpKQt6jecsek5tEwEA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Agp4UEUN; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Agp4UEUN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 74D6AC4CEE5; Sun, 9 Mar 2025 09:15:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1741511758; bh=K3xV6qADVt+GGw/9neE6bZZlut/7sckI+B8ywCNR4bI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Agp4UEUNLiZ/4p+WyhtsvefIfmqewPW6oSk/fWVfF81VQy//ViK+4dFXKvbgmc2p9 RlXrdnjQ6WLEOhFYjoGwZ5jLOUKpPNpSvX3Kxp7A8/7+D1EqgMdj6PfegSN260Vv0x 4eCjVjkV47jldDK2O2JAznIY94taldka3mDNFvkU= Date: Sun, 9 Mar 2025 10:14:41 +0100 From: "gregkh@linuxfoundation.org" To: Aditya Garg Cc: "bhelgaas@google.com" , "joro@8bytes.org" , "will@kernel.org" , "robin.murphy@arm.com" , "andriy.shevchenko@linux.intel.com" , "linux-staging@lists.linux.dev" , Linux Kernel Mailing List , "linux-pci@vger.kernel.org" , "iommu@lists.linux.dev" , Aun-Ali Zaidi , "paul@mrarm.io" , Orlando Chamberlain Subject: Re: [PATCH RFC] staging: Add driver to communicate with the T2 Security Chip Message-ID: <2025030937-antihero-sandblast-7c87@gregkh> References: <1A12CB39-B4FD-4859-9CD7-115314D97C75@live.com> <2025030931-tattoo-patriarch-006d@gregkh> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Sun, Mar 09, 2025 at 09:03:29AM +0000, Aditya Garg wrote: > > > > On 9 Mar 2025, at 2:24 PM, gregkh@linuxfoundation.org wrote: > > > > On Sun, Mar 09, 2025 at 08:40:31AM +0000, Aditya Garg wrote: > >> From: Paul Pawlowski > >> > >> This patch adds a driver named apple-bce, to add support for the T2 > >> Security Chip found on certain Macs. > >> > >> The driver has 3 main components: > >> > >> BCE (Buffer Copy Engine) - this is what the files in the root directory > >> are for. This estabilishes a basic communication channel with the T2. > >> VHCI and Audio both require this component. > > > > So this is a new "bus" type? Or a platform resource? Or something > > else? > > It's a PCI device Great, but then is the resources split up into smaller drivers that then bind to it? How does the other devices talk to this? > >> VHCI - this is a virtual USB host controller; keyboard, mouse and > >> other system components are provided by this component (other > >> drivers use this host controller to provide more functionality). > > > > I don't understand, why does a security chip have a USB virtual > > interface in it? What "devices" hang off of it that are found and > > enumerated by the host OS? > > The t2 chip not only handles security, but also has a usb hub, which connects the internal keyboard, trackpad, touchbar, webcam, and other internal devices. The external usb ports are separate. That feels strange, but hey, we've seen worse :) thanks, greg k-h