[PATCH] pinctrl: Add one-register-per-pin type device tree based pinctrl driver
From: Stephen Warren <hidden>
Date: 2012-06-21 22:13:32
Also in:
linux-devicetree, linux-omap, lkml
On 06/19/2012 07:56 AM, Tony Lindgren wrote:
Hi, Below is the pinctrl-single patch updated with hopefully all the Stephen's comments addressed. The binding still needs to be looked at, see relevant parts of the discussion below.
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From: Tony Lindgren <tony@atomide.com> Date: Wed, 6 Jun 2012 04:18:18 -0700 Subject: [PATCH] pinctrl: Add one-register-per-pin type device tree based pinctrl driver Add one-register-per-pin type device tree based pinctrl driver. Currently this driver only works on omap2+ series of processors, where there is either an 8 or 16-bit padconf register for each pin. Support for other similar pinmux controllers can be added. Signed-off-by: Tony Lindgren <tony@atomide.com>diff --git a/Documentation/devicetree/bindings/pinctrl/pinctrl-single.txt b/Documentation/devicetree/bindings/pinctrl/pinctrl-single.txt new file mode 100644 index 0000000..929254c --- /dev/null +++ b/Documentation/devicetree/bindings/pinctrl/pinctrl-single.txt@@ -0,0 +1,106 @@ +One-register-per-pin type device tree based pinctrl driver + +Required properties: +- compatible : "pinctrl-single" + +- reg : offset and length of the register set for the mux registers + +- pinctrl-single,register-width : pinmux register access width in bits + +- pinctrl-single,function-mask : mask of allowed pinmux function bits + in the pinmux register + +- pinctrl-single,pinconf-mask : mask of allowed pinconf bits in the + pinmux register; this gets combined with pinconf mask but is a separate + mask to allow the option of setting pinconf separatately from the + function
Given that this binding doesn't allow describing pin configuration at present, I would simply remove all mention of that property in the binding documentation. It can be added back if/when that feature is added. Any future driver using this binding can refuse to allow pin configuration if that property is missing.
+- pinctrl-single,function-off : function off mode for disabled state if + available and same for all registers; if not, use a value larger than + function-mask to ignore disabling of registers
Rather than requiring an invalid value in this property, shouldn't the lack of a valid function-off value be represented by the property not being present in the DT?
+This driver assumes that there is only one register for each pin, +and uses the common pinctrl bindings as specified in the pinctrl-bindings.txt +document in this directory.
At this point in the file, I think you need to mention that you're switching from describing the top-level device node to describing pin configuration nodes.
+The pinctrl register offsets and default values are specified as pairs
I thought we were going to remove "default" here?
+using pinctrl-single,pins. For example, setting a pin for a device +could be done with: + + pinctrl-single,pins = <0xdc 0x118>; + +Where 0xdc is the offset from the pinctrl register base address for the +device pinctrl register, and 0x118 contains the desired value of the +pinctrl register. See the device example and static board pins example +below for more information.
There should be some explanation only the portion of this value covered by the pinctrl-single,function-mask value is updated in the register.
+This driver tries to avoid understanding pin and function names because of +the extra bloat they would cause especially in the case of a large number +of pins. This driver just sets what is specified for the board in the .dts file. +Further user space debugging tools can be developed to decipher the pin and +function names using debugfs.
There shouldn't be any discussion of a driver here; the binding is a HW description.
+Example:
I only reviewed the binding document, not the code.