From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jacek Anaszewski Subject: Re: Single gpio shared by LED and switch? Date: Mon, 07 Sep 2015 15:03:50 +0200 Message-ID: <55ED8B36.60108@samsung.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mailout2.w1.samsung.com ([210.118.77.12]:14682 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751252AbbIGNDy (ORCPT ); Mon, 7 Sep 2015 09:03:54 -0400 In-reply-to: Sender: linux-gpio-owner@vger.kernel.org List-Id: linux-gpio@vger.kernel.org To: Geert Uytterhoeven Cc: Linus Walleij , "linux-gpio@vger.kernel.org" , "linux-leds@vger.kernel.org" Hi Geert, On 09/01/2015 07:00 PM, Geert Uytterhoeven wrote: > Hi, > > I'm wondering if there already exists a driver for a gpio that's connected > to both an LED and an input switch. > > I'd expect such a hardware configuration to be fairly common, as gpios can be > a limited resource. > Most of the time the gpio would be in output mode, driving the LED, but at > regular intervals the mode would be changed for a very short moment to input, > to monitor the state of the switch. > > I had a quick look at various drivers (and of course at > Documentation/gpio/drivers-on-gpio.txt), but couldn't find any. > > Does such a hybrid of "leds-gpio" and "gpio-keys(-polled)" already exists? Can you share an example of such a circuit? Would it be possible to construct it without additional GPIO driven transistor? -- Best Regards, Jacek Anaszewski