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

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Date:	Mon, 17 Dec 2012 12:51:32 +0100
From:	Wolfgang Grandegger <wg@...ndegger.com>
To:	Roland Stigge <stigge@...com.de>
CC:	rmallon@...il.com, gregkh@...uxfoundation.org,
	linus.walleij@...aro.org, broonie@...nsource.wolfsonmicro.com,
	linux-kernel@...r.kernel.org, w.sang@...gutronix.de,
	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 12/17/2012 12:37 PM, Wolfgang Grandegger wrote:
> Hi Roland,
> 
> On 12/15/2012 12:49 AM, Roland Stigge wrote:
>> Hi Wolfgang,
>>
>> thank you for the patch!
>>
>> On 14/12/12 18:58, Wolfgang Grandegger wrote:
>>> +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;
>>> +
>>> +	__raw_writel(mask, pio + (val ? PIO_SODR : PIO_CODR));
>>> +}
>>> +
>>
>> Without having an AT91 available right now, I guess the hardware
>> interface of this GPIO chip is different from the GPIO block API. While
>> the hardware has clear and set registers, the val parameter of
>> at91_gpiolib_set_block() should be interpreted as the actual output
>> values. See lpc32xx_gpo_set_block() for an example for handling set and
>> clear registers like this: First, set_bits and clear_bits words are
>> calculated from mask and val parameters, and finally written to the
>> respective hardware registers.
>>
>> Note that one .set_block() can result in writing both the set and clear
>> registers of the hardware when val contains both 0s and 1s in
>> respectively masked positions.
> 
> Oops, I obviously did not test GPIO block write. The patch below does
> work now. Feel free to add it to the next version of your series.

The patch lacks an important fix, sorry. Please consider the updated
patch below.

Wolfgang.


>From a1f93ddea9c6c9c6a80d7a02d3c8d9902823fe47 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 |   28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/arch/arm/mach-at91/gpio.c b/arch/arm/mach-at91/gpio.c
index be42cf0..77c6f91 100644
--- a/arch/arm/mach-at91/gpio.c
+++ b/arch/arm/mach-at91/gpio.c
@@ -48,7 +48,9 @@ struct at91_gpio_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 +64,9 @@ 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 +900,16 @@ 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 +919,20 @@ 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;
+	u32 set_bits = val & mask;
+	u32 clr_bits = ~val & mask;
+
+	/* GPIO outputs can only be set at once or cleared at once */
+	if (set_bits)
+		__raw_writel(set_bits, pio + PIO_SODR);
+	if (clr_bits)
+		__raw_writel(clr_bits, pio + PIO_CODR);
+}
+
 static void at91_gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
 {
 	int i;
-- 
1.7.9.5



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