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 9FD404C70; Sun, 9 Mar 2025 08:55:32 +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=1741510532; cv=none; b=Rf8gpvCGPlxD0lRV3D2CcN9GB+Z90BGRDp9TBv61ULFUP0RnI67yk3imcqRtMkpmbiFfTqJ7mRPPXC13rPwpeesdfza89aEPrM9Css6NgB9oICyq1HTTmomHYMxr9ZRWJaEFHH1Eqiu86hr2yNUWJ+vfzcGE5rU3xD3rhSxdyco= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741510532; c=relaxed/simple; bh=Wjt+xysmdxHjcPi7v9Rzrv9MYN7cn5Yh7OgK54RDH6k=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ut8DnPZfFO80effO4ZLQPtD2GsTTX8po8OXU29IKFmsKuM4/tM76FOHh9WXYLf8/5XuzkyY5pOLq+1DYGffim8MAxbex2B3j6cbpDTVuFmnxn6r1NESJHkdjxAGXlcEayW3nwxDQaffMYMUVIRD4OUwZT8QPoc5cPVjf3F2q8JQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=zFVnYnnR; 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="zFVnYnnR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90519C4CEE5; Sun, 9 Mar 2025 08:55:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1741510532; bh=Wjt+xysmdxHjcPi7v9Rzrv9MYN7cn5Yh7OgK54RDH6k=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=zFVnYnnRHzH1G44dELdk5eT87sOfAiwxf63ml+mpd7+zFRa2QfAMzXvtycSwGya0a DF5R4Ro5WR2D446pt22PoSY+6KOpmuF/xQyk+HYslmSUKZ56HqcKp8TAv/9gVPgbiY VeBKQhl2bOZDg2qUrI4GMLBNXMotUzk2Xewon4YY= Date: Sun, 9 Mar 2025 09:54:16 +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: <2025030905-claim-hardiness-4e7b@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=us-ascii Content-Disposition: inline In-Reply-To: <2025030931-tattoo-patriarch-006d@gregkh> On Sun, Mar 09, 2025 at 09:52:38AM +0100, 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? > > > 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? > > And what other drivers use this controller, just normal Linux drivers, > or vendor-specific ones? > > > Audio - a driver for the T2 audio interface, currently only audio > > output is supported. > > Again, is this a platform device or does it sit on the BCE "bus" you > will create here? Also, it looks like you are creating some new user/kernel apis here (i.e. a char device for a USB host controller?) So those need to be explained a lot as to what they are for and who is using them as I really don't understand their need, nor know what userspace code controls them. thanks, greg k-h