Use of pinctrl-single for external device over I2C

Vaibhav Hiremath
2015-06-23T10:56:17Z

Hi,

I am working on enabling support for PMIC 88PM860 device in the
mainline.

In 88PM860 (and family of devices) few pins are labelled as GPIO's, to
be precise, in 88PM860, we have 8 GPIO's (ana & dig).

I was looking at pinctrl-single driver, as it seems it can not handle
pinmux configuration of external device (in this case its over I2C), as
it uses raw read/write api's.

I see below lines in the driver,

/*
* REVISIT: Reads and writes could eventually use regmap or something
* generic. But at least on omaps, some mux registers are performance
* critical as they may need to be remuxed every time before and after
* idle. Adding tests for register access width for every read and
* write like regmap is doing is not desired, and caching the registers
* does not help in this case.
*/

Should be not have flag for this and use regmap_ variants? If we
implement flag based approach then same driver can be reused for pinmux
configuration of external device.

Just to give more clarity, Let me describe my use-case below,

The platform which I have is based on PXA1928 and 88PM860 chipsets,
where 88PM860.GPIO_0 is connected back to PXA1928.EXT_32K_IN.

GPIO_0 need to configured in mode '4'.

As per spec, 88PM860.GPIO_0 can be configured to

000 = GPIO input mode
001 = GPIO output mode
010 = SLEEPOUTN mirror mode
011 = Buck4 FPWM enable
100 = 32 Khz output buffer mode
101 = PMICINTN output mode
110 = HW_RESET1 mode
111 = HW_RESET2 mode

Please let me know if there is already an alternative for this, which I
missed.