[2/4] gpio: gpio-generic: add flag to read out output value from reg_set
diff mbox

Message ID 1430321701-13758-3-git-send-email-vladimir_zapolskiy@mentor.com
State New
Headers show

Commit Message

Vladimir Zapolskiy April 29, 2015, 3:34 p.m. UTC
The change introduces BGPIOF_READ_OUTPUT_REG_SET flag for gpio-generic
GPIO chip implementation, which allows to get correct configured value
from reg_set register, input value is still get from reg_dat.

Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
---
 drivers/gpio/gpio-generic.c     |   22 +++++++++++++++++++---
 include/linux/basic_mmio_gpio.h |    1 +
 2 files changed, 20 insertions(+), 3 deletions(-)

Comments

Linus Walleij May 11, 2015, 9:50 a.m. UTC | #1
On Wed, Apr 29, 2015 at 5:34 PM, Vladimir Zapolskiy
<vladimir_zapolskiy@mentor.com> wrote:

> The change introduces BGPIOF_READ_OUTPUT_REG_SET flag for gpio-generic
> GPIO chip implementation, which allows to get correct configured value
> from reg_set register, input value is still get from reg_dat.
>
> Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>

Looks reasonable. Patch applied.

Do we need device tree bindings for this?

Yours,
Linus Walleij
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Vladimir Zapolskiy May 11, 2015, 1:28 p.m. UTC | #2
On 11.05.2015 12:50, Linus Walleij wrote:
> On Wed, Apr 29, 2015 at 5:34 PM, Vladimir Zapolskiy
> <vladimir_zapolskiy@mentor.com> wrote:
> 
>> The change introduces BGPIOF_READ_OUTPUT_REG_SET flag for gpio-generic
>> GPIO chip implementation, which allows to get correct configured value
>> from reg_set register, input value is still get from reg_dat.
>>
>> Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
> 
> Looks reasonable. Patch applied.
> 
> Do we need device tree bindings for this?

I don't think so, particular drivers have this as a fixed property, and
"basic-mmio-gpio" has no device tree bindings.

OTOH let see on dynamics of the flag usage, if it grows, it may happen
that its negation is a better candidate for a quirk.

--
With best wishes,
Vladimir

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Patch
diff mbox

diff --git a/drivers/gpio/gpio-generic.c b/drivers/gpio/gpio-generic.c
index 3f90be8..83258b6 100644
--- a/drivers/gpio/gpio-generic.c
+++ b/drivers/gpio/gpio-generic.c
@@ -135,6 +135,17 @@  static unsigned long bgpio_pin2mask_be(struct bgpio_chip *bgc,
 	return 1 << (bgc->bits - 1 - pin);
 }
 
+static int bgpio_get_set(struct gpio_chip *gc, unsigned int gpio)
+{
+	struct bgpio_chip *bgc = to_bgpio_chip(gc);
+	unsigned long pinmask = bgc->pin2mask(bgc, gpio);
+
+	if (bgc->dir & pinmask)
+		return bgc->read_reg(bgc->reg_set) & pinmask;
+	else
+		return bgc->read_reg(bgc->reg_dat) & pinmask;
+}
+
 static int bgpio_get(struct gpio_chip *gc, unsigned int gpio)
 {
 	struct bgpio_chip *bgc = to_bgpio_chip(gc);
@@ -416,7 +427,8 @@  static int bgpio_setup_accessors(struct device *dev,
 static int bgpio_setup_io(struct bgpio_chip *bgc,
 			  void __iomem *dat,
 			  void __iomem *set,
-			  void __iomem *clr)
+			  void __iomem *clr,
+			  unsigned long flags)
 {
 
 	bgc->reg_dat = dat;
@@ -437,7 +449,11 @@  static int bgpio_setup_io(struct bgpio_chip *bgc,
 		bgc->gc.set_multiple = bgpio_set_multiple;
 	}
 
-	bgc->gc.get = bgpio_get;
+	if (!(flags & BGPIOF_UNREADABLE_REG_SET) &&
+	    (flags & BGPIOF_READ_OUTPUT_REG_SET))
+		bgc->gc.get = bgpio_get_set;
+	else
+		bgc->gc.get = bgpio_get;
 
 	return 0;
 }
@@ -500,7 +516,7 @@  int bgpio_init(struct bgpio_chip *bgc, struct device *dev,
 	bgc->gc.ngpio = bgc->bits;
 	bgc->gc.request = bgpio_request;
 
-	ret = bgpio_setup_io(bgc, dat, set, clr);
+	ret = bgpio_setup_io(bgc, dat, set, clr, flags);
 	if (ret)
 		return ret;
 
diff --git a/include/linux/basic_mmio_gpio.h b/include/linux/basic_mmio_gpio.h
index 0e97856..14eea94 100644
--- a/include/linux/basic_mmio_gpio.h
+++ b/include/linux/basic_mmio_gpio.h
@@ -74,5 +74,6 @@  int bgpio_init(struct bgpio_chip *bgc, struct device *dev,
 #define BGPIOF_UNREADABLE_REG_SET	BIT(1) /* reg_set is unreadable */
 #define BGPIOF_UNREADABLE_REG_DIR	BIT(2) /* reg_dir is unreadable */
 #define BGPIOF_BIG_ENDIAN_BYTE_ORDER	BIT(3)
+#define BGPIOF_READ_OUTPUT_REG_SET     BIT(4) /* reg_set stores output value */
 
 #endif /* __BASIC_MMIO_GPIO_H */