linux-kernel - Re: [PATCH 1/1] gpio: add Lynxpoint chipset gpio driver.

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Message-ID: <50C71BC3.2090006@linux.intel.com>
Date:	Tue, 11 Dec 2012 13:40:51 +0200
From:	Mathias Nyman <mathias.nyman@...ux.intel.com>
To:	Grant Likely <grant.likely@...retlab.ca>
CC:	linus.walleij@...aro.org, mika.westerberg@...ux.intel.com,
	rafael.j.wysocki@...el.com, linux-kernel@...r.kernel.org,
	linux-acpi@...r.kernel.org
Subject: Re: [PATCH 1/1] gpio: add Lynxpoint chipset gpio driver.

On 12/11/2012 01:07 AM, Grant Likely wrote:
> On Fri,  7 Dec 2012 16:01:39 +0200, Mathias Nyman<mathias.nyman@...ux.intel.com>  wrote:
>> Add gpio support for Intel Lynxpoint chipset.
>> Lynxpoint supports 94 gpio pins which can generate interrupts.
>> Driver will fail requests for pins that are marked as owned by ACPI, or
>> set in an alternate mode (non-gpio).
>>
>> Signed-off-by: Mathias Nyman<mathias.nyman@...ux.intel.com>
>> ---
>> +static void lp_gpio_set(struct gpio_chip *chip, unsigned gpio, int value)
>> +{
>> +	struct lp_gpio *lg = container_of(chip, struct lp_gpio, chip);
>> +	unsigned long reg = gpio_reg(chip, gpio, LP_CONFIG1);
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&lg->lock, flags);
>> +
>> +	if (value)
>> +		outl(inl(reg) | OUT_LVL_BIT, reg);
>> +	else
>> +		outl(inl(reg)&  ~OUT_LVL_BIT, reg);
>> +
>> +	spin_unlock_irqrestore(&lg->lock, flags);
>> +}
>
> A *lot* of drivers implement their own GPIO ops like this, and they all
> end up looking the same. Please take a look at
> drivers/gpio/gpio-generic.c and see if you can use the stock operations
> provided there.
>
> g.
>

Look quite similar but turns out the only potential generic ones which 
could be used are the bgpio_set() and bgpio_get() funtions. Using them 
would require custom pin2mask, write_reg, read_reg, etc functions.
bgpio_set_direction

I guess using gpio-generic code fits memory mapped devices better. 
Trying to use it for io port devices would require a lot of code mangling.

-Mathias
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