linux-kernel - RE: [PATCH 3/3] GPIO: gpio-dwapb: Suspend & Resume PM enabling

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Message-ID: <4656BEB6164FC34F8171C6538F1A595B2E981942@SHSMSX101.ccr.corp.intel.com>
Date:	Mon, 1 Sep 2014 03:20:00 +0000
From:	"Chen, Alvin" <alvin.chen@...el.com>
To:	atull <atull@...nsource.altera.com>
CC:	Linus Walleij <linus.walleij@...aro.org>,
	Alexandre Courbot <gnurou@...il.com>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"Ong, Boon Leong" <boon.leong.ong@...el.com>,
	"Shevchenko, Andriy" <andriy.shevchenko@...el.com>,
	"Westerberg, Mika" <mika.westerberg@...el.com>,
	"Kweh, Hock Leong" <hock.leong.kweh@...el.com>,
	Darren Hart <dvhart@...ux.intel.com>
Subject: RE: [PATCH 3/3] GPIO: gpio-dwapb: Suspend & Resume PM enabling

> > +/* Store GPIO context across system-wide suspend/resume transitions
> > +*/ static struct gpio_saved_regs {
> > +	unsigned long data;
> > +	unsigned long dir;
> > +	unsigned long int_en;
> > +	unsigned long int_mask;
> > +	unsigned long int_type;
> > +	unsigned long int_pol;
> > +	unsigned long int_deb;
> > +} saved_regs;
> > +
> > +static int dwapb_gpio_suspend(struct device *dev) {
> > +	struct platform_device *pdev = to_platform_device(dev);
> > +	struct dwapb_gpio *gpio = platform_get_drvdata(pdev);
> > +	struct bgpio_chip *bgc	= &gpio->ports[0].bgc;
> > +	unsigned long flags;
> > +
> > +	spin_lock_irqsave(&bgc->lock, flags);
> > +
> > +	saved_regs.int_mask	= dwapb_read(gpio, GPIO_INTMASK);
> > +	saved_regs.int_en	= dwapb_read(gpio, GPIO_INTEN);
> > +	saved_regs.int_deb	= dwapb_read(gpio, GPIO_PORTA_DEBOUNCE);
> > +	saved_regs.int_pol	= dwapb_read(gpio, GPIO_INT_POLARITY);
> > +	saved_regs.int_type	= dwapb_read(gpio, GPIO_INTTYPE_LEVEL);
> > +	saved_regs.dir		= dwapb_read(gpio, GPIO_SWPORTA_DDR);
> > +	saved_regs.data		= dwapb_read(gpio, GPIO_SWPORTA_DR);
> 
> Hello,
> 
> The DesignWare GPIO IP can be configured to have ports a, b, c, and d. So you
> will need to save and restore any ports that are present.  I think that *some*
> configurations of the IP include a register that can tell us how it was configured,
> but that register is also optional :)  I don't have confidence that we can
> read/write the registers blindly whether they are known to be there or not.
> So you may be stuck with looking at the device tree or platform data to know
> whether banks b, c, or d exist.
>
>From the code, the device node has one property for port index. If the index is '0', then it is port A.
So I think we can store the status according to the port index.

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