pinctrl: add bcm2835 driver

The BCM2835 GPIO module is a combined GPIO controller, (GPIO) interrupt
controller, and pinmux/control device.

Original driver by Simon Arlott.
Rewrite including GPIO chip device by Chris Boot.

Upstreaming changes by Stephen Warren:
* Wrote DT binding documentation.
* Changed brcm,function to an integer to more directly match the
  datasheet, and to match brcm,pins being an integer.
* Implemented pull-up/down pin config.
* Removed read-only DT property and related code. The restriction this
  implemented are driven by the board, not the GPIO HW block, so don't
  really make sense of a HW block binding, were in general incomplete
  (since they could only know about the few pins hard-coded into the
  Raspberry Pi B board design and not the uncommitted GPIOS), and are
  better represented simply by not writing incorrect data into pin
  configuration nodes.
* Don't set GPIO_IN function select in gpio_request_enable() to avoid
  glitches; defer this to gpio_set_direction(). Consequently, removed
  empty bcm2835_pmx_gpio_request_enable().
* Simplified enabled_irq_map[]; make it explicitly 1 entry per bank.
* Lifted use of enabled_irq_map[] outside the per-interrupt loop in
  IRQ handler, thus fixing an issue where the code was indexing into
  enabled_irq_map[] by intra-bank GPIO ID, not global GPIO ID.
* Removed locking in IRQ handler, since all other code uses
  spin_lock_irqsave() and so guarantees it doesn't run concurrently
  with the handler.
* Moved duplicated BUILD_BUG_ON()s into probe(). Also check size of
  bcm2835_gpio_pins[].
* Remove range-checking from bcm2835_pctl_get_groups_count() since we've
  decided to trust the pinctrl core.
* Made bcm2835_pmx_gpio_disable_free() call bcm2835_pinctrl_fsel_set()
  directly for simplicity.
* Fixed body of dt_free_map() to match latest dt_node_to_map().
* Removed GPIO ownership check from bcm2835_pmx_enable() since the pinctrl
  core owns doing this.
* Made irq_chip and pinctrl_gpio_range .name == MODULE_NAME so it's more
  descriptive.
* Simplified remove(); removed call to non-existent
  pinctrl_remove_gpio_range(), remove early return on error.
* Don't force gpiochip's base to 0. Set gpio_range.base to gpiochip's
  base GPIO number.
* Error-handling cleanups in probe().
* Switched to module_platform_driver() rather than open-coding.
* Made pin, group, and function names lower-case.
* s/broadcom/brcm/ in DT property names.
* s/2708/2835/.
* Fixed a couple minor checkpatch warnings, and other minor cleanup.

Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Signed-off-by: Chris Boot <bootc@bootc.net>
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/pinctrl/brcm,bcm2835-gpio.txt

@@ -0,0 +1,74 @@
+Broadcom BCM2835 GPIO (and pinmux) controller
+
+The BCM2835 GPIO module is a combined GPIO controller, (GPIO) interrupt
+controller, and pinmux/control device.
+
+Required properties:
+- compatible: "brcm,bcm2835-gpio"
+- reg: Should contain the physical address of the GPIO module's registes.
+- gpio-controller: Marks the device node as a GPIO controller.
+- #gpio-cells : Should be two. The first cell is the pin number and the
+  second cell is used to specify optional parameters:
+  - bit 0 specifies polarity (0 for normal, 1 for inverted)
+- interrupts : The interrupt outputs from the controller. One interrupt per
+  individual bank followed by the "all banks" interrupt.
+- interrupt-controller: Marks the device node as an interrupt controller.
+- #interrupt-cells : Should be 2.
+  The first cell is the GPIO number.
+  The second cell is used to specify flags:
+    bits[3:0] trigger type and level flags:
+      1 = low-to-high edge triggered.
+      2 = high-to-low edge triggered.
+      4 = active high level-sensitive.
+      8 = active low level-sensitive.
+    Valid combinations are 1, 2, 3, 4, 8.
+
+Please refer to ../gpio/gpio.txt for a general description of GPIO bindings.
+
+Please refer to pinctrl-bindings.txt in this directory for details of the
+common pinctrl bindings used by client devices, including the meaning of the
+phrase "pin configuration node".
+
+Each pin configuration node lists the pin(s) to which it applies, and one or
+more of the mux function to select on those pin(s), and pull-up/down
+configuration. Each subnode only affects those parameters that are explicitly
+listed. In other words, a subnode that lists only a mux function implies no
+information about any pull configuration. Similarly, a subnode that lists only
+a pul parameter implies no information about the mux function.
+
+Required subnode-properties:
+- brcm,pins: An array of cells. Each cell contains the ID of a pin. Valid IDs
+  are the integer GPIO IDs; 0==GPIO0, 1==GPIO1, ... 53==GPIO53.
+
+Optional subnode-properties:
+- brcm,function: Integer, containing the function to mux to the pin(s):
+  0: GPIO in
+  1: GPIO out
+  2: alt5
+  3: alt4
+  4: alt0
+  5: alt1
+  6: alt2
+  7: alt3
+- brcm,pull: Integer, representing the pull-down/up to apply to the pin(s):
+  0: none
+  1: down
+  2: up
+
+Each of brcm,function and brcm,pull may contain either a single value which
+will be applied to all pins in brcm,pins, or 1 value for each entry in
+brcm,pins.
+
+Example:
+
+	gpio: gpio {
+		compatible = "brcm,bcm2835-gpio";
+		reg = <0x2200000 0xb4>;
+		interrupts = <2 17>, <2 19>, <2 18>, <2 20>;
+
+		gpio-controller;
+		#gpio-cells = <2>;
+
+		interrupt-controller;
+		#interrupt-cells = <2>;
+	};

drivers/pinctrl/Kconfig

@@ -26,6 +26,11 @@ config DEBUG_PINCTRL
 	help
 	  Say Y here to add some extra checks and diagnostics to PINCTRL calls.
 
+config PINCTRL_BCM2835
+	bool
+	select PINMUX
+	select PINCONF
+
 config PINCTRL_IMX
 	bool
 	select PINMUX

drivers/pinctrl/Makefile

@@ -9,6 +9,7 @@ ifeq ($(CONFIG_OF),y)
 obj-$(CONFIG_PINCTRL)		+= devicetree.o
 endif
 obj-$(CONFIG_GENERIC_PINCONF)	+= pinconf-generic.o
+obj-$(CONFIG_PINCTRL_BCM2835)	+= pinctrl-bcm2835.o
 obj-$(CONFIG_PINCTRL_IMX)	+= pinctrl-imx.o
 obj-$(CONFIG_PINCTRL_IMX35)	+= pinctrl-imx35.o
 obj-$(CONFIG_PINCTRL_IMX51)	+= pinctrl-imx51.o