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3c702e9987
linux/drivers/gpio
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Linus Walleij 3c702e9987 gpio: add a userspace chardev ABI for GPIOs 
A new chardev that is to be used for userspace GPIO access is
added in this patch. It is intended to gradually replace the
horribly broken sysfs ABI.

Using a chardev has many upsides:

- All operations are per-gpiochip, which is the actual
  device underlying the GPIOs, making us tie in to the
  kernel device model properly.

- Hotpluggable GPIO controllers can come and go, as this
  kind of problem has been know to userspace for character
  devices since ages, and if a gpiochip handle is held in
  userspace we know we will break something, whereas the
  sysfs is stateless.

- The one-value-per-file rule of sysfs is really hard to
  maintain when you want to twist more than one knob at a time,
  for example have in-kernel APIs to switch several GPIO
  lines at the same time, and this will be possible to do
  with a single ioctl() from userspace, saving a lot of
  context switching.

We also need to add a new bus type for GPIO. This is
necessary for example for userspace coldplug, where sysfs is
traversed to find the boot-time device nodes and create the
character devices in /dev.

This new chardev ABI is *non* *optional* and can be counted
on to be present in the future, emphasizing the preference
of this ABI.

The ABI only implements one single ioctl() to get the name
and number of GPIO lines of a chip. Even this is debatable:
see it as a minimal example for review. This ABI shall be
ruthlessly reviewed and etched in stone.

The old /sys/class/gpio is still optional to compile in,
but will be deprecated.

Unique device IDs are created using IDR, which is overkill
and insanely scalable, but also well tested.

Cc: Johan Hovold <johan@kernel.org>
Cc: Michael Welling <mwelling@ieee.org>
Cc: Markus Pargmann <mpa@pengutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-02-09 11:09:35 +01:00
..
devres.c gpio: make flags mandatory for gpiod_get functions 2015-07-06 10:39:24 +02:00
gpio-74x164.c gpio: 74x164: use gpiochip data pointer 2016-01-05 11:21:01 +01:00
gpio-74xx-mmio.c gpio: generic: factor into gpio_chip struct 2016-01-05 11:21:00 +01:00
gpio-104-idi-48.c gpio: 104-idi-48: use gpiochip data pointer 2016-01-05 11:21:01 +01:00
gpio-104-idio-16.c gpio: 104-idio-16: use gpiochip data pointer 2016-01-05 11:21:01 +01:00
gpio-adnp.c gpio: adnp: use gpiochip data pointer 2016-01-05 11:21:01 +01:00
gpio-adp5520.c gpio: adp5520: use gpiochip data pointer 2016-01-05 11:21:02 +01:00
gpio-adp5588.c gpio: adp5588: use gpiochip data pointer 2016-01-05 11:21:02 +01:00
gpio-altera.c gpio: altera: use gpiochip data pointer 2016-01-05 11:21:02 +01:00
gpio-amd8111.c gpio: amd8111: use gpiochip data pointer 2016-01-05 11:21:02 +01:00
gpio-amdpt.c gpio: amdpt: use gpiochip data pointer 2016-01-05 11:21:02 +01:00
gpio-arizona.c GPIO bulk updates for the v4.5 kernel cycle: 2016-01-17 12:32:01 -08:00
gpio-ath79.c gpio: ath79: use gpiochip data pointer 2016-01-05 11:21:03 +01:00
gpio-bcm-kona.c gpio: bcm-kona: use gpiochip data pointer 2016-01-05 11:21:03 +01:00
gpio-brcmstb.c gpio: brcmstb: Set endian flags for big-endian MIPS 2016-01-07 16:25:09 +01:00
gpio-bt8xx.c gpio: bt8xx: use gpiochip data pointer 2016-01-05 11:21:03 +01:00
gpio-clps711x.c gpio: generic: factor into gpio_chip struct 2016-01-05 11:21:00 +01:00
gpio-crystalcove.c gpio: crystalcove: use gpiochip data pointer 2016-01-05 11:21:04 +01:00
gpio-cs5535.c gpio: cs5535: use gpiochip data pointer 2016-01-05 11:21:04 +01:00
gpio-da9052.c gpio: da9052: use gpiochip data pointer 2016-01-05 11:21:04 +01:00
gpio-da9055.c gpio: da9055: use gpiochip data pointer 2016-01-05 11:21:04 +01:00
gpio-davinci.c gpio: davinci: use gpiochip data pointer 2016-01-05 11:21:04 +01:00
gpio-dln2.c gpio: dln2: use gpiochip data pointer 2016-01-05 11:21:05 +01:00
gpio-dwapb.c gpio: generic: factor into gpio_chip struct 2016-01-05 11:21:00 +01:00
gpio-em.c gpio: em: use gpiochip data pointer 2016-01-05 11:21:05 +01:00
gpio-ep93xx.c gpio: generic: factor into gpio_chip struct 2016-01-05 11:21:00 +01:00
gpio-etraxfs.c gpio: generic: factor into gpio_chip struct 2016-01-05 11:21:00 +01:00
gpio-f7188x.c gpio: f7188: use gpiochip data pointer 2016-01-05 11:21:05 +01:00
gpio-ge.c gpio: generic: factor into gpio_chip struct 2016-01-05 11:21:00 +01:00
gpio-generic.c gpio: generic: factor into gpio_chip struct 2016-01-05 11:21:00 +01:00
gpio-grgpio.c gpio: generic: factor into gpio_chip struct 2016-01-05 11:21:00 +01:00
gpio-ich.c gpio: convert remaining users to gpiochip_add_data() 2016-01-05 11:21:20 +01:00
gpio-intel-mid.c gpio: intel-mid: use gpiochip data pointer 2016-01-05 11:21:05 +01:00
gpio-iop.c gpio: convert remaining users to gpiochip_add_data() 2016-01-05 11:21:20 +01:00
gpio-it87.c gpio: it87: use gpiochip data pointer 2016-01-05 11:21:06 +01:00
gpio-janz-ttl.c gpio: convert remaining users to gpiochip_add_data() 2016-01-05 11:21:20 +01:00
gpio-kempld.c gpio: kempld: use gpiochip data pointer 2016-01-05 11:21:06 +01:00
gpio-ks8695.c gpio: convert remaining users to gpiochip_add_data() 2016-01-05 11:21:20 +01:00
gpio-loongson.c gpio: convert remaining users to gpiochip_add_data() 2016-01-05 11:21:20 +01:00
gpio-lp3943.c gpio: lp3943: use gpiochip data pointer 2016-01-05 11:21:06 +01:00
gpio-lpc18xx.c gpio: lpc18xx: use gpiochip data pointer 2016-01-05 11:21:06 +01:00
gpio-lpc32xx.c gpio: lpc32xx: use gpiochip data pointer 2016-01-05 11:21:06 +01:00
gpio-lynxpoint.c gpio: lynxpoint: use gpiochip data pointer 2016-01-05 11:21:07 +01:00
gpio-max730x.c gpio: max730x: use gpiochip data pointer 2016-01-05 11:21:07 +01:00
gpio-max732x.c gpio: max732x: use gpiochip data pointer 2016-01-05 11:21:07 +01:00
gpio-max7300.c gpio: Drop owner assignment from i2c_driver 2015-11-30 09:31:00 +01:00
gpio-max7301.c spi: Drop owner assignment from spi_drivers 2015-10-28 10:30:17 +09:00
gpio-mb86s7x.c gpio: mb86s7x: use gpiochip data pointer 2016-01-05 11:21:07 +01:00
gpio-mc9s08dz60.c gpio: mc9s08dz60: use gpiochip data pointer 2016-01-05 11:21:08 +01:00
gpio-mc33880.c gpio: mc33880: use gpiochip data pointer 2016-01-05 11:21:07 +01:00
gpio-mcp23s08.c gpio: mcp: use gpiochip data pointer 2016-01-05 11:21:08 +01:00
gpio-ml-ioh.c gpio: ml-ioh: use gpiochip data pointer 2016-01-05 11:21:08 +01:00
gpio-mm-lantiq.c gpio: mm-lantiq: Do not use gpiochip_get_data() in ltq_mm_save_regs() 2016-01-13 10:21:06 +01:00
gpio-moxart.c gpio: moxart: fix build regression 2016-01-07 16:16:38 +01:00
gpio-mpc8xxx.c gpio: mpc8xxx: Do not use gpiochip_get_data() in mpc8xxx_gpio_save_regs() 2016-01-13 10:22:23 +01:00
gpio-mpc5200.c gpio: mpc5200: use gpiochip data pointer 2016-01-05 11:21:08 +01:00
gpio-msic.c gpio: msic: use gpiochip data pointer 2016-01-05 11:21:09 +01:00
gpio-mvebu.c gpio: mvebu: use gpiochip data pointer 2016-01-05 11:21:09 +01:00
gpio-mxc.c gpio: generic: factor into gpio_chip struct 2016-01-05 11:21:00 +01:00
gpio-mxs.c gpio: generic: factor into gpio_chip struct 2016-01-05 11:21:00 +01:00
gpio-octeon.c gpio: octeon: use gpiochip data pointer 2016-01-05 11:21:10 +01:00
gpio-omap.c gpio: omap: use gpiochip data pointer 2016-01-05 11:21:10 +01:00
gpio-palmas.c gpio: palmas: use gpiochip data pointer 2016-01-05 11:21:10 +01:00
gpio-pca953x.c gpio: pca953x: use gpiochip data pointer 2016-01-05 11:21:11 +01:00
gpio-pcf857x.c gpio: pcf857x: use gpiochip data pointer 2016-01-05 11:21:11 +01:00
gpio-pch.c gpio: pch: Optimize pch_gpio_get() 2016-01-05 15:46:34 +01:00
gpio-pl061.c gpio: pl061: use gpiochip data pointer 2016-01-05 11:21:11 +01:00
gpio-pxa.c gpio: pxa: use gpiochip data pointer 2016-01-05 11:21:12 +01:00
gpio-rc5t583.c gpio: rc5t583: use gpiochip data pointer 2016-01-05 11:21:12 +01:00
gpio-rcar.c gpio: rcar: use gpiochip data pointer 2016-01-05 11:21:12 +01:00
gpio-rdc321x.c gpio: rdc321x: use gpiochip data pointer 2016-01-05 11:21:12 +01:00
gpio-sa1100.c gpio: convert remaining users to gpiochip_add_data() 2016-01-05 11:21:20 +01:00
gpio-sch311x.c gpio: sch311x: use gpiochip data pointer 2016-01-05 11:21:13 +01:00
gpio-sch.c gpio: sch: use gpiochip data pointer 2016-01-05 11:21:13 +01:00
gpio-sodaville.c gpio: generic: factor into gpio_chip struct 2016-01-05 11:21:00 +01:00
gpio-spear-spics.c gpio: spear-spics: use gpiochip data pointer 2016-01-05 11:21:13 +01:00
gpio-sta2x11.c gpio: sta2x11: use gpiochip data pointer 2016-01-05 11:21:13 +01:00
gpio-stmpe.c gpio: stmpe: use gpiochip data pointer 2016-01-05 11:21:14 +01:00
gpio-stp-xway.c gpio: stp-xway: use gpiochip data pointer 2016-01-05 11:21:14 +01:00
gpio-sx150x.c gpio: sx150x: use gpiochip data pointer 2016-01-05 11:21:14 +01:00
gpio-syscon.c gpio: syscon: use gpiochip data pointer 2016-01-05 11:21:14 +01:00
gpio-tb10x.c gpio: tb10x: use gpiochip data pointer 2016-01-05 11:21:15 +01:00
gpio-tc3589x.c gpio: tc3589x: use gpiochip data pointer 2016-01-05 11:21:15 +01:00
gpio-tegra.c gpio: convert remaining users to gpiochip_add_data() 2016-01-05 11:21:20 +01:00
gpio-timberdale.c gpio: timberdale: use gpiochip data pointer 2016-01-05 11:21:15 +01:00
gpio-tps6586x.c gpio: tps6586x: use gpiochip data pointer 2016-01-05 11:21:15 +01:00
gpio-tps65910.c gpio: tps65910: use gpiochip data pointer 2016-01-05 11:21:15 +01:00
gpio-tps65912.c gpio: tps65912: use gpiochip data pointer 2016-01-05 11:21:16 +01:00
gpio-ts5500.c gpio: ts5500: use gpiochip data pointer 2016-01-05 11:21:16 +01:00
gpio-twl4030.c gpio: twl4030: use gpiochip data pointer 2016-01-05 11:21:16 +01:00
gpio-twl6040.c gpio: convert remaining users to gpiochip_add_data() 2016-01-05 11:21:20 +01:00
gpio-tz1090-pdc.c gpio: tz1090-pdc: use gpiochip data pointer 2016-01-05 11:21:16 +01:00
gpio-tz1090.c gpio: tz1090: use gpiochip data pointer 2016-01-05 11:21:16 +01:00
gpio-ucb1400.c gpio: ucb1400: use gpiochip data pointer 2016-01-05 11:21:17 +01:00
gpio-vf610.c gpio: vf610: use gpiochip data pointer 2016-01-05 11:21:17 +01:00
gpio-viperboard.c gpio: viperboard: use gpiochip data pointer 2016-01-05 11:21:17 +01:00
gpio-vr41xx.c gpio: convert remaining users to gpiochip_add_data() 2016-01-05 11:21:20 +01:00
gpio-vx855.c gpio: vx855: use gpiochip data pointer 2016-01-05 11:21:18 +01:00
gpio-wm831x.c gpio: wm831x: use gpiochip data pointer 2016-01-05 11:21:18 +01:00
gpio-wm8350.c gpio: wm8350: use gpiochip data pointer 2016-01-05 11:21:18 +01:00
gpio-wm8994.c gpio: wm8994: use gpiochip data pointer 2016-01-05 11:21:18 +01:00
gpio-xgene-sb.c gpio: generic: factor into gpio_chip struct 2016-01-05 11:21:00 +01:00
gpio-xgene.c gpio: xgene: use gpiochip data pointer 2016-01-05 11:21:19 +01:00
gpio-xilinx.c gpio: xilinx: Do not use gpiochip_get_data() in xgpio_save_regs() 2016-01-07 10:06:56 +01:00
gpio-xlp.c gpio: xlp: use gpiochip data pointer 2016-01-05 11:21:19 +01:00
gpio-xtensa.c gpio: convert remaining users to gpiochip_add_data() 2016-01-05 11:21:20 +01:00
gpio-zevio.c gpio: zevio: use gpiochip data pointer 2016-01-05 11:21:19 +01:00
gpio-zx.c gpio: zx: use gpiochip data pointer 2016-01-05 11:21:19 +01:00
gpio-zynq.c gpio: zynq: use gpiochip data pointer 2016-01-05 11:21:20 +01:00
gpiolib-acpi.c GPIO bulk updates for the v4.5 kernel cycle: 2016-01-17 12:32:01 -08:00
gpiolib-legacy.c gpiolib: Split GPIO flags parsing and GPIO configuration 2015-10-16 22:46:46 +02:00
gpiolib-of.c gpio: of: provide optional of_mm_gpiochip_add_data() function 2016-01-05 11:20:12 +01:00
gpiolib-sysfs.c gpio: make the gpiochip a real device 2016-02-09 11:03:53 +01:00
gpiolib.c gpio: add a userspace chardev ABI for GPIOs 2016-02-09 11:09:35 +01:00
gpiolib.h gpio: add a userspace chardev ABI for GPIOs 2016-02-09 11:09:35 +01:00
Kconfig ARM: SoC multiplatform code changes for v4.5 2016-01-20 18:03:56 -08:00
Makefile ARM: SoC multiplatform code changes for v4.5 2016-01-20 18:03:56 -08:00