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:
>From b44cad16cbbca84715dffd4cb5268497216add25 Mon Sep 17 00:00:00 2001
From: Wolfgang Grandegger <w...@grandegger.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 <w...@grandegger.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;
--
1.7.9.5
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