From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1524639115; cv=none; d=google.com; s=arc-20160816; b=Ny+42O6Q5MAQO50ErxTXyVohNIOc2nUI+enVDAVd0Ok0byP82BCAhpQRBj3M7tLgQn 74TIo5sG3n3l27HwG05mKjPw3Efn7CzjEYG0hSzy6xh7FF4ViU4YDAwPYZKXfoknNS4A KfWixlpOilLGEUW2ZJ8QZ1wnZ7EdC6ETwaPKDmYvNlp3V7RSwKfqvLbNcGIYUFv96k8f YcmTwTmszU3yZlOV3QYycTgRqj1rshO1NxA51+tlF7GOwHzrJ6QZbjyWqmRRAsEXC5/c 51yH26BSmAbSBELizHA29za56TIyZ+kH0skdkL8CBs+4QRifmXINw0ziS2oB/7wZWlm1 gZBw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:sender:dkim-signature :arc-authentication-results; bh=deTgewHoF+xkeUfMySaQ895CDn3NVIxOtBJVr60y4NI=; b=yBSFIBgm52PO/mEKkazIRL0WRK3ng5l1TI25jgbpC5WJZjxsvmflkQqH1tVvJc68Zx leQgi8updtT4u2eQ7vB+zLGVXvxTWFw5B/upZQ0+sXI2opmYVqxwDm2DjJ/AsJDp24k6 1aXfUhKIRfMFRdL++6gr6A4MuzwmldDrb7zPyCVmzyUMukOFY8OMeSkAWyMVr54WKVN1 1XhyB4uo7+HRZ1CYvKoOgH6cxEzvGJZ/1GzXfo6K5Aeuam6tt8vwUGSXGJLLGoRXnRHB bWT9bILLHzgN/njuuImavIm2qRzA912fW9jVw6DBdjbuhnnsb+4diwFEb1Br8PsV3pwN UlvA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=UkZcBXAu; spf=pass (google.com: domain of jhovold@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=jhovold@gmail.com Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=UkZcBXAu; spf=pass (google.com: domain of jhovold@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=jhovold@gmail.com X-Google-Smtp-Source: AB8JxZrlgZPPcj66Oc8n3rzNCfOrgo91wHgu0SqLXJjQyVK0ytfKQKtpr5eSoXtjay3visd8PDpr5Q== Sender: Johan Hovold Date: Wed, 25 Apr 2018 08:51:46 +0200 From: Johan Hovold To: Pavel Machek Cc: Johan Hovold , Greg Kroah-Hartman , Rob Herring , Mark Rutland , Andreas Kemnade , Arnd Bergmann , "H . Nikolaus Schaller" , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org Subject: Re: [PATCH 0/7] gnss: add new GNSS subsystem Message-ID: <20180425065146.GH4615@localhost> References: <20180424163458.11947-1-johan@kernel.org> <20180425062659.GA5352@amd> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180425062659.GA5352@amd> User-Agent: Mutt/1.9.5 (2018-04-13) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1598647061282688193?= X-GMAIL-MSGID: =?utf-8?q?1598699985224888428?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Wed, Apr 25, 2018 at 08:26:59AM +0200, Pavel Machek wrote: > Hi! > > > This series adds a new subsystem for GNSS receivers (e.g. GPS > > receivers). > > > > While GNSS receivers are typically accessed using a UART interface they > > often also support other I/O interfaces such as I2C, SPI and USB, while > > yet other devices use iomem or even some form of remote-processor > > messaging (rpmsg). > > > > The new GNSS subsystem abstracts the underlying interface and provides a > > new "gnss" class type, which exposes a character-device interface (e.g. > > /dev/gnss0) to user space. This allows GNSS receivers to have a > > representation in the Linux device model, something which is important > > not least for power management purposes and which also allows for easy > > detection and (eventually) identification of GNSS devices. > > Actually... no, what you done is not GNSS subsystem. It is generic > subsystem for a link + some controls, typically for power. > > Yes, that setup is common for GPS receivers, but it is there also for > modems (droid 4: usb + gpios) and bluetooth dongles (n900: serial + > gpios). Those would be handled by other subsystems. The idea here is that eventually there may be more GNSS specific bits added, such as 1PPS support that I already mentioned. If someone is crazy enough to put a location service in the kernel with a more high-level interface (an in-kernel gpsd) they can try, but I'm more and more convinced that needs to remain in user space. I did also already mentioned however, that some hybrid approach may be doable, such as handling port setup over NMEA/UBX/SiRF from within the kernel. Johan