linux-kernel - Re: [PATCH RESEND 0/6 v10] gpio: Add block GPIO

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Date:	Mon, 17 Dec 2012 22:33:29 +0100
From:	Roland Stigge <stigge@...com.de>
To:	Wolfgang Grandegger <wg@...ndegger.com>
CC:	rmallon@...il.com, gregkh@...uxfoundation.org,
	linus.walleij@...aro.org, broonie@...nsource.wolfsonmicro.com,
	w.sang@...gutronix.de, linux-kernel@...r.kernel.org,
	grant.likely@...retlab.ca, daniel-gl@....net, sr@...x.de,
	plagnioj@...osoft.com, linux-arm-kernel@...ts.infradead.org,
	highguy@...il.com
Subject: Re: [PATCH RESEND 0/6 v10] gpio: Add block GPIO

On 17/12/12 20:47, Wolfgang Grandegger wrote:
> On 12/17/2012 07:02 PM, Roland Stigge wrote:
>> On 12/17/2012 06:37 PM, Wolfgang Grandegger wrote:
>>> 	/* Do synchronous data output with a single write access */
>>> 	__raw_writel(~mask, pio + PIO_OWDR);
>>> 	__raw_writel(mask, pio + PIO_OWER);
>>> 	__raw_writel(val, pio + PIO_ODSR);
>>>
>>> For caching we would need a storage. Not sure if it's worth compared to
>>> a context switch into the kernel.
>>
>> Block GPIO is not only for you in userspace. ;-) You can also implement
>> efficient n-bit bus I/O in kernel drivers, n-bit-banging. :-) So not
>> always context switches involved.
> 
> OK, what do you think about the following untested patch:

Looks good!

Why "untested"? ;-)

Thanks,

Roland

>>>From b44cad16cbbca84715dffd4cb5268497216add25 Mon Sep 17 00:00:00 2001
> From: Wolfgang Grandegger <wg@...ndegger.com>
> Date: Mon, 3 Dec 2012 08:31:55 +0100
> Subject: [PATCH 1/2] gpio: add GPIO block callback functions for AT91
> 
> Signed-off-by: Wolfgang Grandegger <wg@...ndegger.com>
> ---
>  arch/arm/mach-at91/gpio.c |   29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/arch/arm/mach-at91/gpio.c b/arch/arm/mach-at91/gpio.c
> index be42cf0..cf6bd45 100644
> --- a/arch/arm/mach-at91/gpio.c
> +++ b/arch/arm/mach-at91/gpio.c
> @@ -42,13 +42,16 @@ struct at91_gpio_chip {
>  	void __iomem		*regbase;	/* PIO bank virtual address */
>  	struct clk		*clock;		/* associated clock */
>  	struct irq_domain	*domain;	/* associated irq domain */
> +	unsigned long		mask_shadow;	/* synchronous data output */
>  };
>  
>  #define to_at91_gpio_chip(c) container_of(c, struct at91_gpio_chip, chip)
>  
>  static void at91_gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip);
>  static void at91_gpiolib_set(struct gpio_chip *chip, unsigned offset, int val);
> +static void at91_gpiolib_set_block(struct gpio_chip *chip, unsigned long mask, unsigned long val);
>  static int at91_gpiolib_get(struct gpio_chip *chip, unsigned offset);
> +static unsigned long at91_gpiolib_get_block(struct gpio_chip *chip, unsigned long mask);
>  static int at91_gpiolib_direction_output(struct gpio_chip *chip,
>  					 unsigned offset, int val);
>  static int at91_gpiolib_direction_input(struct gpio_chip *chip,
> @@ -62,7 +65,9 @@ static int at91_gpiolib_to_irq(struct gpio_chip *chip, unsigned offset);
>  			.direction_input  = at91_gpiolib_direction_input, \
>  			.direction_output = at91_gpiolib_direction_output, \
>  			.get		  = at91_gpiolib_get,		\
> +			.get_block	  = at91_gpiolib_get_block,	\
>  			.set		  = at91_gpiolib_set,		\
> +			.set_block	  = at91_gpiolib_set_block,	\
>  			.dbg_show	  = at91_gpiolib_dbg_show,	\
>  			.to_irq		  = at91_gpiolib_to_irq,	\
>  			.ngpio		  = nr_gpio,			\
> @@ -896,6 +901,16 @@ static int at91_gpiolib_get(struct gpio_chip *chip, unsigned offset)
>  	return (pdsr & mask) != 0;
>  }
>  
> +static unsigned long at91_gpiolib_get_block(struct gpio_chip *chip, unsigned long mask)
> +{
> +	struct at91_gpio_chip *at91_gpio = to_at91_gpio_chip(chip);
> +	void __iomem *pio = at91_gpio->regbase;
> +	u32 pdsr;
> +
> +	pdsr = __raw_readl(pio + PIO_PDSR);
> +	return pdsr & mask;
> +}
> +
>  static void at91_gpiolib_set(struct gpio_chip *chip, unsigned offset, int val)
>  {
>  	struct at91_gpio_chip *at91_gpio = to_at91_gpio_chip(chip);
> @@ -905,6 +920,20 @@ static void at91_gpiolib_set(struct gpio_chip *chip, unsigned offset, int val)
>  	__raw_writel(mask, pio + (val ? PIO_SODR : PIO_CODR));
>  }
>  
> +static void at91_gpiolib_set_block(struct gpio_chip *chip, unsigned long mask, unsigned long val)
> +{
> +	struct at91_gpio_chip *at91_gpio = to_at91_gpio_chip(chip);
> +	void __iomem *pio = at91_gpio->regbase;
> +
> +	/* Do synchronous data output with a single write access */
> +	if (mask != at91_gpio->mask_shadow) {
> +		at91_gpio->mask_shadow = mask;
> +		__raw_writel(~mask, pio + PIO_OWDR);
> +		__raw_writel(mask, pio + PIO_OWER);
> +	}
> +	__raw_writel(val, pio + PIO_ODSR);
> +}
> +
>  static void at91_gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
>  {
>  	int i;

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