On Monday 23 September 2013 01:36 PM, Linus Walleij wrote:
On Fri, Sep 20, 2013 at 2:30 PM, Laxman Dewangan <ldewangan@xxxxxxxxxx> wrote:
+Required subnode properties:
+---------------------------
+reg: The GPIO number on which the properties need to be applied.
+
+Optional subnode properties:
+---------------------------
+bias-pull-up: The Pull-up for the pin to be enable.
+bias-pull-down: Pull down of the pins to be enable.
+bias-high-impedance: High impedance of the pin to be enable.
+open-drain: Pin is open drain type.
+function: IO functionality of the pins. The valid options are:
+ gpio, intrrupt-output, vsup-vbat-low-undeb, interrupt-input,
+ pwm-input, voltage-stby, oc-powergood-sd0, powergood-output,
+ clk32k-output, watchdog-input, soft-reset-input, pwm-output,
+ vsup-vbat-low-deb, oc-powergood-sd6
+ Missing the function property will set the pin in GPIO mode.
This is pin control. Do not try to shoehorn pin control drivers into
the GPIO subsystem. Take a good day off, read through
Documentation/pinctrl.txt and come back with a thoroughly rewritten
driver in drivers/pinctrl/pinctrl-as3722.c.
We already have generic device tree bindings for all of the above
properties, and a library for generic pin config in the pin control
subsystem to handle them. Look at recent drivers for
inspiration.
Yes, the appropriate location is pin control for pull up/down etc
configuration but with this device, the actual issue is with the way it
is require to configure the pull up/down and input/output of the pin.
There is no separate bits for pull up/down and direction and it is
clubbed together. The register's bits are defined as:
Selects the GPIO mode (I, I/O, Tri, Pulls) (BIT 2:0)
0 : Input
1 : Output (push and pull) VSUP_GPIO
2 : Output/Input (open drain, only NMOS is active)
3 : ADC input (Tristate)
4 : Input with pull-up to VDD_GPIO_lv
5 : Input with pull-down
6 : Output/Input open drain (nmos) with pull-up to VDD_GPIO_lv,
7 : Output (push and pull) VDD_GPIO_lv
So I can not actually configure the pull up/down, open drain and
direction independently until every thing is known.
Direction come from gpio driver but pull up/down and open drain
configuration come from the pin control.
And this is only the reason to make all configuration in single driver.
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