linux-kernel - Re: [PATCH] pinctrl: Add generic pinctrl-simple driver that supports omap2+ padconf

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Date:	Fri, 4 May 2012 17:32:51 +0200
From:	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
To:	Tony Lindgren <tony@...mide.com>
Cc:	Stephen Warren <swarren@...dotorg.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	linux-omap@...r.kernel.org, Stephen Warren <swarren@...dia.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] pinctrl: Add generic pinctrl-simple driver that
 supports omap2+ padconf

On 08:03 Fri 04 May     , Tony Lindgren wrote:
> * Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com> [120503 22:08]:
> > 
> > In my mind in the driver we do not have to care how to list
> > register/unregister the group. We just need to be able to do this
> > 
> > pinctrl_register_group(...)
> > 
> > or 
> > 
> > pinctrl_unregistewr_group(...)
> > 
> > On at91 we have this type of controller
> 
> Ah I see. Yeah makes sense. Also I think we should let the pinctrl
> core eventually manage the pins more too. Right now the pins are
> a static array in the driver, which makes things unnecessarily
> complex for the DT case. It would be nice to also have something like
> pinctrl_register/unregister_pin instead of requiring them all
> be registered while registering with the framework initially.
> 
> But all that can be improved later on once we get the binding down..
agreed at 100%
>  
> > one pin can have multiple function and each function can be on different pin
> > and we need to program and represent each of them one by one
> > 
> > And each pin have different parameter
> > 
> > so I was thinking to do like on gpio
> > 
> > uart {
> > 	pin = < &pioA 12 {pararms} >
> > 
> > }
> 
> Hmm I assume the "12" above the gpio number?
no pin number in the bank because it could not be gpio

evenif on at91 and nearly on the controller I known it is the case
>  
> > and use macro as basicaly we are just this
> > 
> > and this can be applied to tegra too as you will just refer the pin in this hw
> > pin block
> 
> I was thinking of adding gpio eventually as a separate attribute with
> something like the following. Here cam_d10 pin is used as gpio109:
> 
> cam_d10.gpio_109 {
> 	pinctrl-simple,cells = <0xfa 0x104>;	/* OMAP_PIN_INPUT | OMAP_MUX_MODE4 */
> 	gpio = <&gpio4 13 0>;			/* gpio109 */
> };
> 
> The reasoning for this is that as we may not care about the gpio number
> for all pins, it should be optional. Would that work for you?
yes

but I was thinking to put it as a param but why not

my idea was this

pinctrl@...ff200 {
	#address-cells = <1>;
	#size-cells = <0>;
	compatible = "atmel,at91rm9200-pinctrl";

	atmel,mux-mask = <
		/*    A	  B     */
		 0xffffffff 0xffc003ff  /* pioA */
		 0xffffffff 0x800f8f00  /* pioB */
		 0xffffffff 0x00000e00  /* pioC */
		 0xffffffff 0xff0c1381  /* pioD */
		 0xffffffff 0x81ffff81  /* pioE */
		>;

	pioA: gpio@...ff200 {
		compatible = "atmel,at91rm9200-gpio";
		reg = <0xfffff200 0x100>;
		interrupts = <2 4>;
		#gpio-cells = <2>;
		gpio-controller;
		interrupt-controller;
	};

	pioB: gpio@...ff400 {
		compatible = "atmel,at91rm9200-gpio";
		reg = <0xfffff400 0x100>;
		interrupts = <3 4>;
		#gpio-cells = <2>;
		gpio-controller;
		interrupt-controller;
	};

	pioC: gpio@...ff600 {
		compatible = "atmel,at91rm9200-gpio";
		reg = <0xfffff600 0x100>;
		interrupts = <4 4>;
		#gpio-cells = <2>;
		gpio-controller;
		interrupt-controller;
	};

	pioD: gpio@...ff800 {
		compatible = "atmel,at91rm9200-gpio";
		reg = <0xfffff800 0x100>;
		interrupts = <5 4>;
		#gpio-cells = <2>;
		gpio-controller;
		interrupt-controller;
	};

	pioE: gpio@...ffa00 {
		compatible = "atmel,at91rm9200-gpio";
		reg = <0xfffffa00 0x100>;
		interrupts = <5 4>;
		#gpio-cells = <2>;
		gpio-controller;
		interrupt-controller;
	};

	dbgu {
		pins = < &pioB 12 0 0
			 &pioB 13 0 2 >;
	/* with macro */
		pins = < &pioB 12 MUX_A NO_PULL_UP
			 &pioB 13 MUX_A PULL_UP >;
	};

	/* and also the notion of linked group
	 * as on uart of network you have often the same subset of pin use.
	 *
	 * As example on uart rxd/txd is use for the group without rts/cts
	 * and the one with it
	 * on ethernet the RMII pin are use also on MII
	 */

	uart0_rxd_txd {
		pins = < &pioB 19 MUX_A PULL_UP		/* rxd */
			 &pioB 18 MUX_A NO_PULL_UP >;	/* txd */
	};

	uart0_rts_cts {
		groups = < &uart0_rxd_txd >;
		pins = < &pioB 17 MUX_B NO_PULL_UP	/* rts */
			 &pioB 15 MUX_B NO_PULL_UP >;	/* cts */
	};

	uart0_rts_cts_external_pull_up {
		groups = < &uart0_rts_cts >;
		gpios = <&pioC 1 0>;
	};
};

The idea is to avoid duplication the xlate for pins will be driver specific
with maybe a common implementation

the 3 or 4 first fix as done on gpio

Best Regards,
J.
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