Return-Path: Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Subject: Re: [RFC PATCH 0/3] UART slave device bus From: Marcel Holtmann In-Reply-To: Date: Thu, 18 Aug 2016 19:31:05 +0200 Cc: Rob Herring , Greg Kroah-Hartman , Jiri Slaby , Sebastian Reichel , Pavel Machek , Peter Hurley , NeilBrown , "Dr . H . Nikolaus Schaller" , Arnd Bergmann , "linux-bluetooth@vger.kernel.org" , "linux-serial@vger.kernel.org" , "linux-kernel@vger.kernel.org" Message-Id: References: <20160818011445.22726-1-robh@kernel.org> To: Linus Walleij Sender: linux-kernel-owner@vger.kernel.org List-ID: Hi Linus, >> Currently, devices attached via a UART are not well supported in the >> kernel. The problem is the device support is done in tty line disciplines, >> various platform drivers to handle some sideband, and in userspace with >> utilities such as hciattach. > > Freaking *awesome* Rob, this really really needs to happen. > I'm very happy that you're driving this. > >> This is functional with minimal testing using the loopback driver and >> pl011 (w/o DMA) UART under QEMU (modified to add a DT node for the slave >> device). It still needs lots of work and polish. > > I have Bluetooth (HCI) over UART on the Nomadik and Ux500, > both with DMA support for the PL011 too. So I hope to be able > to utilize this. > > (The HCI transport is then used for GPS, FM radio and whatnot > but that is another issue.) that is something we can already solve via regmap. We have started work on Intel LnP which also includes a FM radio chip where registers/interrupts are exposed via HCI commands/events. So fundamentally the Bluetooth HCI device would expose the GPS and FM radio nodes via regmap. Regards Marcel