linux-kernel - Re: [PATCH] gpio: add a driver for GPIO pins found on AMD-8111 south bridge chips

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Date:	Fri, 18 May 2012 16:35:32 -0600
From:	Grant Likely <grant.likely@...retlab.ca>
To:	Linus Walleij <linus.walleij@...aro.org>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>
Cc:	Linus Walleij <linus.walleij@...ricsson.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gpio: add a driver for GPIO pins found on AMD-8111 south bridge chips

On Fri, 27 Apr 2012 12:52:19 +0200, Linus Walleij <linus.walleij@...aro.org> wrote:
> On Fri, Apr 27, 2012 at 12:08 PM, Dmitry Eremin-Solenikov
> <dbaryshkov@...il.com> wrote:
> 
> > Add a driver to use GPIO pins available on several AMD south bridges
> > (currently only AMD 8111 is supported).
> >
> > Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@...il.com>
> 
> Mainly nitpicks, it's looking good overall...

Hi Dimtry,

Do you have an updated version of this patch to address Linus' comments?

g.

> 
> > +       spin_lock_irqsave(&agp->lock, flags);
> > +       temp = ioread8(agp->pm - PMBASE_OFFSET + PMBASE_GPIO(offset));
> > +       temp = (temp & 0x1c) | (!!value);
> 
> This is a bit idomatic but I think I understand what's going on. However this
> 0x1C magic could be better of with some #define AMD_8111_GPIO_FOO don't
> you think?
> 
> > +static int amd_gpio_get(struct gpio_chip *chip, unsigned offset)
> > +{
> > +       struct amd_gpio *agp = to_agp(chip);
> > +       u8 temp;
> > +
> > +       temp = ioread8(agp->pm - PMBASE_OFFSET + PMBASE_GPIO(offset));
> > +
> > +       dev_dbg(&agp->pdev->dev, "Getting gpio %d, reg=%02x\n", offset, temp);
> > +
> > +       return !!(temp & 0x20);
> 
> And this could be #define AMD_8111_GPIO_INVAL or so (I bet this bit has a
> name in the datasheet, right?)
> 
> > +static int amd_gpio_dirout(struct gpio_chip *chip, unsigned offset, int value)
> > +{
> > +       struct amd_gpio *agp = to_agp(chip);
> > +       u8 temp;
> > +       unsigned long flags;
> > +
> > +       spin_lock_irqsave(&agp->lock, flags);
> > +       temp = ioread8(agp->pm - PMBASE_OFFSET + PMBASE_GPIO(offset));
> > +       temp = (temp & 0x10) | 0x4 | (!!value);
> 
> And so on...
> 
> > +       iowrite8(temp, agp->pm - PMBASE_OFFSET + PMBASE_GPIO(offset));
> > +       spin_unlock_irqrestore(&agp->lock, flags);
> > +
> > +       dev_dbg(&agp->pdev->dev, "Dirout gpio %d, value %d, reg=%02x\n", offset, !!value, temp);
> > +
> > +       return 0;
> > +}
> 
> > +static int __init mod_init(void)
> 
> amd_gpio_init() maybe? These names are nice for e.g. ftrace.
> 
> > +       printk(KERN_INFO "AMD-8111 GPIO detected\n");
> 
> pr_info() & friends are nice shorthands for this.
> 
> > +static void __exit mod_exit(void)
> 
> amd_gpio_mod_exit()?
> 
> > +MODULE_AUTHOR("The Linux Kernel team");
> 
> Don't be shy, put in your own name :-)
> 
> Yours,
> Linus Walleij

-- 
Grant Likely, B.Sc, P.Eng.
Secret Lab Technologies, Ltd.
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