linux-kernel - Re: [PATCH] gpio: Add device driver for GRGPIO cores

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Date:	Sat, 2 Feb 2013 16:16:06 +0100
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Andreas Larsson <andreas@...sler.com>
Cc:	Grant Likely <grant.likely@...retlab.ca>,
	Rob Herring <rob.herring@...xeda.com>,
	linux-kernel@...r.kernel.org, devicetree-discuss@...ts.ozlabs.org,
	software@...sler.com
Subject: Re: [PATCH] gpio: Add device driver for GRGPIO cores

On Wed, Jan 30, 2013 at 1:28 PM, Andreas Larsson <andreas@...sler.com> wrote:

> This driver supports GRGPIO gpio cores available in the GRLIB VHDL IP core
> library.
>
> Signed-off-by: Andreas Larsson <andreas@...sler.com>

OK...

> +#if defined(__BIG_ENDIAN)
> +static inline u32 grgpio_read_reg(u32 __iomem *reg)
> +{
> +       return ioread32be(reg);
> +}
> +
> +static inline void grgpio_write_reg(u32 __iomem *reg, u32 val)
> +{
> +       iowrite32be(val, reg);
> +}
> +#else
> +static inline u32 grgpio_read_reg(u32 __iomem *reg)
> +{
> +       return ioread32(reg);
> +}
> +
> +static inline void grgpio_write_reg(u32 __iomem *reg, u32 val)
> +{
> +       iowrite32(val, reg);
> +}
> +#endif

Where is this __BIG_ENDIAN flag coming from?

And do you really have and test this regularly on both LE and BE hardware?
I am worrying a bit about maintenance...

> +static void grgpio_set_sbit(struct grgpio_priv *priv, u32 __iomem *reg,
> +                          unsigned offset, int val, u32 *shadow)
> +{
> +       unsigned long flags;
> +
> +       spin_lock_irqsave(&priv->lock, flags);
> +
> +       if (val)
> +               *shadow |= (1 << offset);
> +       else
> +               *shadow &= ~(1 << offset);
> +       grgpio_write_reg(reg, *shadow);
> +
> +       spin_unlock_irqrestore(&priv->lock, flags);
> +}

This is all very basic stuff. Please make a best effort to reuse or
augment and reuse this:
drivers/gpio/gpio-generic.c

IIRC this one also handles endianness issues, but I could be wrong.

Yours,
Linus Walleij
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