Messages in this thread | | | Date | Thu, 9 Feb 2012 11:31:35 +0530 | From | Laxman Dewangan <> | Subject | Re: [PATCH V1] regulator: fixed: Support for open-drain gpio |
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On Tuesday 07 February 2012 05:13 PM, Mark Brown wrote: > * PGP Signed by an unknown key > > On Tue, Feb 07, 2012 at 04:16:36PM +0530, Laxman Dewangan wrote: > >> To make the pin to high/low for enabling/disabling the switches, >> the pins will have the pull-up connected and the high/low can be >> set using following methods: >> LOW: gpio_direction_output(gpio, 0) ... this drives the signal >> and overrides the pullup. >> HIGH: gpio_direction_input(gpio) ... this turns off the output, >> so the pullup (or some other device) controls the signal. > Thinking about this further this is potentially going to apply to any > GPIO output - perhaps we should push the implementation down into > gpiolib so we just specify a flag when requesting the GPIO and then > gpiolib does the pull low/high Z thing for us. That would be much less > effort in individual drivers, we'd just need to be able to set the flag > and could potentially directly use any hardware open drain output > support (some GPIO controllers will do all this in hardware) if the > driver API were extended. Grant, does that sound reasonable? > If Grant agree on this then we can have following thing: - we have already apis like gpio_request_one() and gpio_request_multiple() which take the flags. - We need to add the flag GPIOF_OD in current list of flags for requester. - In the gpio_request_xx(), just store this flag in gpio_desc for corresponding gpios. - When client set direction_output() with val 1 then do direction_input(). So check will be in function direction_output() - When client call set_value(), again check for value ==1 and GPIO_OD and if it is there, call direction_input.
On client side change, call proper request function with proper flag (with GPIOF_OD if it is require).
Does it sound good?
> * Unknown Key > * 0x6E30FDDD
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