From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1524588643; cv=none; d=google.com; s=arc-20160816; b=suOXyIu7ZJME6uLs0JYMc4EMTmiTM2+ig+3f1liAAYPqRVafFsnqXe0N19q1WDltIN A8B9nm1wbXS1SknUBxmK/eb+SDkmKnamU5jv5WSqVArzcXyfTsun6oBt0+h4GSG0XcmG 4S3Tuyf2FQpkNktGQy4jJrgAK3uN4M7z+v8K8PXeofheypy2oVt1nKA8xCOfOtsaGnko Vz6VZu7a+ht38rzuc01SRmlRSqO3kV0jze/7GeVdNIuyVKBc6Zn7gMOIBt4KgaEWO2Op VFOGPmynUdYm377D5JYXWyGORC5Jtcbe3w+87pU2hyGS90HIcvMLAEwl7odB+J/5zyGI snJg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=message-id:date:subject:cc:to:from:sender:dkim-signature :arc-authentication-results; bh=smZW1BPwnSB7S678WB1zMleOqc2SV2CG8eD9q6upYXs=; b=QeoiaIS9Xed32l31SVYoSCMN3JpGxnT7CdNX6NOF/XfSea8Y9V5+jyPVapaF4zWiku 65C26urmnTUOiBl8ged41XPSDLk9V7nyLRAMd8iFb0sWZS3OAwsA1/kjfhRPefkNqVPD ia0FTuKvso+UnAdIg+8s3NbstydcHSqVv9c0oQcwedHrJel6CCBbx0Cne9ddtTLACCdk SS+S2+bvwo8UAMQ1Qf8zokyRBlV+gof2jAiHOCGlggcIpHEL6x5AmoZgGJnOObbh6t6O 7Nc6SC+XjzGOWwf+Xu72L+KtvspF9XhxscvWZvBZFsxLDJ8P9EzQo5bNjKSHwiLUXBqL TsAg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=nhqO+i/W; spf=pass (google.com: domain of jhovold@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=jhovold@gmail.com Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=nhqO+i/W; spf=pass (google.com: domain of jhovold@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=jhovold@gmail.com X-Google-Smtp-Source: AB8JxZrYwgbkWqISvUnB0c25Yklkh0ObwKH4Z2TEePFAxqvvoR+J53eOXdOIV2OZbktzOwaaTJlfyQ== Sender: Johan Hovold From: Johan Hovold To: Greg Kroah-Hartman , Rob Herring , Mark Rutland Cc: Andreas Kemnade , Arnd Bergmann , "H . Nikolaus Schaller" , Pavel Machek , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Johan Hovold Subject: [PATCH 0/7] gnss: add new GNSS subsystem Date: Tue, 24 Apr 2018 18:34:51 +0200 Message-Id: <20180424163458.11947-1-johan@kernel.org> X-Mailer: git-send-email 2.17.0 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1598647061282688193?= X-GMAIL-MSGID: =?utf-8?q?1598647061282688193?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 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. Note that the character-device interface provides raw access to whatever protocol the receiver is (currently) using, such as NMEA 0183, UBX or SiRF Binary. These protocols are expected to be continued to be handled by user space for the time being, even if some hybrid solutions are also conceivable (e.g. to have kernel drivers issue management commands). This will still allow for better platform integration by allowing GNSS devices and their resources (e.g. regulators and enable-gpios) to be described by firmware and managed by kernel drivers rather than platform-specific scripts and services. While the current interface is kept minimal, it could be extended using IOCTLs, sysfs or uevents as needs and proper abstraction levels are identified and determined (e.g. for device and feature identification). Another possible extension is to add generic 1PPS support. I decided to go with a custom character-device interface rather than pretend that these abstract GNSS devices are still TTY devices (e.g. /dev/ttyGNSS0). Obviously, modifying line settings or reading modem control signals does not make any sense for a device using, say, a USB (not USB-serial) or iomem interface. This also means, however, that user space would no longer be able to set the line speed to match a new port configuration that can be set using the various GNSS protocols when the underlying interface is indeed a UART; instead this would need to be taken care of by the driver. Also note that writes are always synchronous instead of requiring user space to call tcdrain() after every command. This all seems to work well-enough (e.g. with gpsd), but please let me know if I've overlooked something which would indeed require a TTY interface instead. As proof-of-concept I have implemented drivers for receivers based on two common GNSS chipsets (SiRFstar and u-blox), but due to lack of hardware these have so far only been tested using mockup devices and a USB-serial-based GPS device (using out-of-tree code). [ Let me know if you've got any evalutation kits to spare. ] Finally, note that documentation (including kerneldoc) remains to be written, but hopefully this will not hinder review given that the current interfaces are fairly self-describing. Johan Johan Hovold (7): gnss: add GNSS receiver subsystem dt-bindings: add generic gnss binding gnss: add generic serial driver dt-bindings: gnss: add u-blox binding gnss: add driver for u-blox receivers dt-bindings: gnss: add sirfstar binding gnss: add driver for sirfstar-based receivers .../devicetree/bindings/gnss/gnss.txt | 36 ++ .../devicetree/bindings/gnss/sirfstar.txt | 38 ++ .../devicetree/bindings/gnss/u-blox.txt | 31 ++ .../devicetree/bindings/vendor-prefixes.txt | 4 + MAINTAINERS | 7 + drivers/Kconfig | 2 + drivers/Makefile | 1 + drivers/gnss/Kconfig | 43 ++ drivers/gnss/Makefile | 16 + drivers/gnss/core.c | 385 ++++++++++++++++ drivers/gnss/serial.c | 288 ++++++++++++ drivers/gnss/serial.h | 47 ++ drivers/gnss/sirf.c | 415 ++++++++++++++++++ drivers/gnss/ubx.c | 133 ++++++ include/linux/gnss.h | 64 +++ 15 files changed, 1510 insertions(+) create mode 100644 Documentation/devicetree/bindings/gnss/gnss.txt create mode 100644 Documentation/devicetree/bindings/gnss/sirfstar.txt create mode 100644 Documentation/devicetree/bindings/gnss/u-blox.txt create mode 100644 drivers/gnss/Kconfig create mode 100644 drivers/gnss/Makefile create mode 100644 drivers/gnss/core.c create mode 100644 drivers/gnss/serial.c create mode 100644 drivers/gnss/serial.h create mode 100644 drivers/gnss/sirf.c create mode 100644 drivers/gnss/ubx.c create mode 100644 include/linux/gnss.h -- 2.17.0