From fa76a3db7093a527333c380df82a0f158d9b8299 Mon Sep 17 00:00:00 2001 From: Sonic Zhang Date: Thu, 9 Apr 2015 11:13:07 +0800 Subject: pinctrl: allow exlusive GPIO/mux pin allocation Disallow simultaneous use of the the GPIO and peripheral mux functions by setting a flag "strict" in struct pinctrl_desc. The blackfin pinmux and gpio controller doesn't allow user to set up a pin for both GPIO and peripheral function. So, add flag strict in struct pinctrl_desc to check both gpio_owner and mux_owner before approving the pin request. v2-changes: - if strict flag is set, check gpio_owner and mux_onwer in if and else clause v3-changes: - add kerneldoc for this struct - augment Documentation/pinctrl.txt Signed-off-by: Sonic Zhang Signed-off-by: Linus Walleij --- Documentation/pinctrl.txt | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'Documentation/pinctrl.txt') diff --git a/Documentation/pinctrl.txt b/Documentation/pinctrl.txt index a9b47163bb5d..d6b2bed94c43 100644 --- a/Documentation/pinctrl.txt +++ b/Documentation/pinctrl.txt @@ -73,6 +73,7 @@ static struct pinctrl_desc foo_desc = { .pins = foo_pins, .npins = ARRAY_SIZE(foo_pins), .owner = THIS_MODULE, + .strict = true, }; int __init foo_probe(void) @@ -830,6 +831,11 @@ separate memory range only intended for GPIO driving, and the register range dealing with pin config and pin multiplexing get placed into a different memory range and a separate section of the data sheet. +A flag "strict" in struct pinctrl_desc is available to check and deny +simultaneous access to the same pin from GPIO and pin multiplexing +consumers on hardware of this type. The pinctrl driver should set this flag +accordingly. + (B) pin config @@ -850,6 +856,11 @@ possible that the GPIO, pin config and pin multiplex registers are placed into the same memory range and the same section of the data sheet, although that need not be the case. +In some pin controllers, although the physical pins are designed in the same +way as (B), the GPIO function still can't be enabled at the same time as the +peripheral functions. So again the "strict" flag should be set, denying +simultaneous activation by GPIO and other muxed in devices. + From a kernel point of view, however, these are different aspects of the hardware and shall be put into different subsystems: -- cgit v1.2.3