linux-kernel - Re: [PATCH v2 2/4] gpio: add LP3943 I2C GPIO expander driver

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Date:	Wed, 7 Aug 2013 20:49:22 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	"Kim, Milo" <Milo.Kim@...com>
Cc:	"lee.jones@...aro.org" <lee.jones@...aro.org>,
	"Samuel Ortiz (sameo@...ux.intel.com)" <sameo@...ux.intel.com>,
	"broonie@...nel.org" <broonie@...nel.org>,
	"thierry.reding@...il.com" <thierry.reding@...il.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-pwm@...r.kernel.org" <linux-pwm@...r.kernel.org>
Subject: Re: [PATCH v2 2/4] gpio: add LP3943 I2C GPIO expander driver

On Tue, Jul 30, 2013 at 2:42 AM, Kim, Milo <Milo.Kim@...com> wrote:

> This is one of LP3943 MFD driver.
> LP3943 is configurable as a GPIO expander, up to 16 GPIOs.
>
> * Application note: how to configure LP3943 as a GPIO expander
>   http://www.ti.com/lit/an/snva287a/snva287a.pdf
>
> * Supported GPIO controller operations
>   request, free, direction_input, direction_output, get and set
>
> * GPIO direction register not supported
>   LP3943 doesn't have the GPIO direction register. It only provides input and
>   output status registers.
>   So, private data for the direction should be handled manually.
>   This variable is updated whenever the direction is changed and
>   used in 'get' operation.
>
> * Pin assignment
>   A driver data, 'pin_used' is checked when a GPIO is requested.
>   If the GPIO is already assigned, then returns as failure.
>   If the GPIO is available, 'pin_used' is set.
>   When the GPIO is not used anymore, then it is cleared.
>   It is defined as unsigned long type for atomic bit operation APIs,
>   but only LSB 16bits are used because LP3943 has 16 outputs.
>
> Cc: Linus Walleij <linus.walleij@...aro.org>
> Signed-off-by: Milo Kim <milo.kim@...com>
> ---
> * Patch v2
>   Use bitops macros for bit manipulations.
>   Support device tree structure for the GPIO controller.
>   Add request() and free() for the pin assignment.

This adresses all my concerns, nice driver.
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>

I guess this will be merged through the MFD tree along
with the MFD core patch? That needs to go in first anyway.

Yours,
Linus Walleij
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