Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759571Ab3GaL3X (ORCPT ); Wed, 31 Jul 2013 07:29:23 -0400 Received: from mail-ea0-f175.google.com ([209.85.215.175]:45252 "EHLO mail-ea0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756147Ab3GaL3V (ORCPT ); Wed, 31 Jul 2013 07:29:21 -0400 From: Tomasz Figa To: Laurent Pinchart Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Benjamin Herrenschmidt , Linus Walleij , linux-gpio@vger.kernel.org, Grant Likely , Guennadi Liakhovetski Subject: Re: How to create IRQ mappings in a GPIO driver that doesn't control its IRQ domain ? Date: Wed, 31 Jul 2013 13:29:26 +0200 Message-ID: <18585358.29goqe5cyM@thinkpad> User-Agent: KMail/4.10.5 (Linux/3.10.1-gentoo; KDE/4.10.5; x86_64; ; ) In-Reply-To: <2175074.sF1r3oKahE@avalon> References: <1624911.6TtmtVmU1T@avalon> <12170068.F0utKQgh5l@flatron> <2175074.sF1r3oKahE@avalon> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5241 Lines: 111 On Wednesday 31 of July 2013 13:11:33 Laurent Pinchart wrote: > Hi Tomasz, > > On Sunday 28 July 2013 12:07:48 Tomasz Figa wrote: > > On Wednesday 24 of July 2013 01:21:44 Laurent Pinchart wrote: > > > Hello, > > > > > > I'm running into an issue on several Renesas SoC with IRQ domains and > > > GPIOs. > > > > > > On sh73a0, r8a73a4 and r8a7740, GPIOs and external interrupts are > > > handled by two separate IP cores, namely the PFC (Pin Function > > > Controller) and INTC (Interrupt Controller). The former is handled by > > > the sh-pfc driver (drivers/pinctrl/sh-pfc) and the later by the > > > irq-renesas-intc-irqpin driver (drivers/irqchip), referred to below as > > > the irqpin driver. > > > > Is the INTC used for anything more than just external interrupts on GPIO > > lines? > > Yes, it also handles other interrupt sources (NMI and peripherals), but > those are not implemented now. The peripheral interrupts are also handled > by the GIC, which is preferred over INTC. OK, this is much more clear now. > > > The sh73a0, for instance, has 32 external interrupt lines that are > > > multiplexed on pins usable as GPIOs. Both the GPIO and external > > > interrupt functions are usable at the same time, which allows reading > > > the state of the interrupt lines. > > > > > > These external interrupts are for MMC/SD support, among other devices. > > > In this specific case the MMC/SD Card Detect signal is wired to one of > > > the external interrupt signals, and the corresponding GPIO is passed to > > > the MMC/SD controller driver. Depending on other configuration > > > parameters the driver can then either poll the Card Detect signal, or > > > register an interrupt handler to detect changes in the signal state. > > > This features is implemented by the MMC/SD core, which call > > > gpio_to_irq() on the GPIO to retrieve the corresponding IRQ number. > > > > > > On non-DT systems the external IRQs are statically mapped at a known > > > offset. The sh-pfc driver, to implement the gpio_to_irq() function > > > (through its gpiochip .to_irq() handler), simply searches a > > > SoC-specific lookup table for the fixed IRQ number associated with a > > > given GPIO. > > > > > > However, on DT systems, IRQs are mapped dynamically on demand. The > > > irqpin driver registers a simple IRQ domain, and the > > > irq_create_mapping() function can then be used to map a given IRQ, > > > specified as an offset in the domain. This is where the problem > > > appears, as the irqchip .to_irq() function is implemented in the sh-pfc > > > > I assume it should be s/irqchip/gpiochip/ in the line above, shouldn't it? > > Yes, my bad. No problem. > > > driver, which doesn't have access to the IRQ domain registered by the > > > irqpin driver. > > > > > > I could hack around this by exporting a function in the irqpin driver > > > that would map an IRQ, and call that function from the sh-pfc driver. > > > I'd rather avoid that solution as it would add a direct dependency > > > between the two drivers. > > > > If you could just get the IRQ domain registered by irqpin driver and use > > it in sh-pfc, then I guess it would solve your problem, as you could > > simply call irq_create_mapping() with the domain and hwirq as args in your > > gpiochip .to_irq() callback. > > > > I'm not sure if it's not a hack, but you could add a property to the node > > of your pin controller that would contain a phandle to your interrupt > > controller. Then you could use of_parse_phandle() to get to device node of > > the INTC and then irq_find_host() to retrieve irq domain associated with > > it. > > That was my initial idea. However, one on of the SoCs, the GPIO interrupts > are divided in two separate blocks, handled by two different interrupt > controller instances. I could thus have a list of phandle + range, but that > becomes pretty hackish. Specifying the interrupts explicitly would be more > extensible. Yes, in this case passing the domain alone makes little sense and domain + range would be a bit hackish indeed. > > > Has anyone run into a similar issue ? My gut feeling is that the > > > architecture isn't right somewhere, but I can't really pinpoint where. > > > As the external IRQs are handled by an IP core separate from the PFC > > > > Well, the fact that it's separate doesn't mean anything yet. Here my > > question whether it's used exclusively for GPIO interrupts or not becomes > > significant. If yes, maybe it could be simply moved to the pinctrl driver? > > Depending on the SoC, I have two different IRQ controllers used for GPIO > interrupts. They're called INTC and IRQC. INTC has other purposes (although > not implemented at the moment). The IRQC instances used for GPIO interrupts > are (at the moment) dedicated to GPIO interrupts, but other instances of the > same IP core are used for other interrupts, so a separate driver makes > sense in my opinion. OK. So you need a bit smarter solution then. Best regards, Tomasz -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/