linux-kernel - Re: [PATCH v2 1/2] i2c-core: dt: Pick i2c bus number from i2c alias if present

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20130210121901.GA15546@nekote.pengutronix.de>
Date:	Sun, 10 Feb 2013 13:19:01 +0100
From:	Wolfram Sang <w.sang@...gutronix.de>
To:	Doug Anderson <dianders@...omium.org>
Cc:	linux-i2c@...r.kernel.org,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Olof Johansson <olof@...om.net>,
	Thomas Abraham <thomas.abraham@...aro.org>,
	Padmavathi Venna <padma.v@...sung.com>,
	Ben Dooks <ben-linux@...ff.org>,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org,
	Haojian Zhuang <haojian.zhuang@...il.com>,
	Arnd Bergmann <arnd@...db.de>,
	Sylwester Nawrocki <sylvester.nawrocki@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] i2c-core: dt: Pick i2c bus number from i2c alias
 if present

Hi Doug,

On Mon, Jan 14, 2013 at 10:53:21AM -0800, Doug Anderson wrote:
> This allows you to get the equivalent functionality of
> i2c_add_numbered_adapter() with all data in the device tree and no
> special case code in your driver.  This is a common device tree
> technique.
> 
> For quick reference, the FDT syntax for using an alias to provide an
> ID looks like:
>   aliases {
>     i2c0 = &i2c_0;
>     i2c1 = &i2c_1;
>   };
> 
> Signed-off-by: Doug Anderson <dianders@...omium.org>
> Acked-by: Haojian Zhuang <haojian.zhuang@...il.com>
> ---
> Changes in v2: None
> 
>  drivers/i2c/i2c-core.c |  105 +++++++++++++++++++++++++++++++++++-------------
>  1 files changed, 77 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> index e388590..a60ed6d 100644
> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -921,13 +921,81 @@ out_list:
>  }
>  
>  /**
> + * i2c_get_number_from_dt - get the adapter number based on dt alias
> + * @adap: the adapter to look at
> + *
> + * Check whether there's an alias in the FDT that gives an ID for this i2c
> + * device.  Use an alias like "i2c<nr>", like:
> + *   aliases {
> + *     i2c0 = &i2c_0;
> + *     i2c1 = &i2c_1;
> + *   };
> + *
> + * Returns the ID if found.  If no alias is found returns -1.
> + */
> +static int i2c_get_number_from_dt(struct i2c_adapter *adap)

i2c_get_id_from_dt()?

> +{
> +	struct device *dev = &adap->dev;
> +	int id;
> +
> +	if (!dev->of_node)
> +		return -1;

-ESOMETHING?

> +
> +	id = of_alias_get_id(dev->of_node, "i2c");
> +	if (id < 0)
> +		return -1;
> +	return id;

Simply 'return of_alias_get_id(...)'? Even more, since this function
boils down to calling of_alias_get_id only and is only used once, I'd
think we can implement that directly and drop this function. That
shouldn't hurt readability.

> +}
> +
> +/**
> + * _i2c_add_numbered_adapter - i2c_add_numbered_adapter where nr is never -1
> + * @adap: the adapter to register (with adap->nr initialized)
> + * Context: can sleep
> + *
> + * See i2c_add_numbered_adapter() for details.
> + */
> +static int _i2c_add_numbered_adapter(struct i2c_adapter *adap)

All other internal functions are prefixed with '__'.

> +{
> +	int	id;
> +	int	status;
> +
> +	/* Handled by wrappers */
> +	BUG_ON(adap->nr == -1);

Is that a reason to halt the kernel? WARN and bailing out would do IMO.

> +
> +	if (adap->nr & ~MAX_IDR_MASK)
> +		return -EINVAL;

Note the idr-cleanup series from Tejun Heo. Given that his series is
scheduled for v3.9, I'd like to have your patches on top of his.

Thanks,

   Wolfram

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/