Skip to contentSkip to conversation

gpio: mmio: handle "ngpios" properly in bgpio_init()

PATCH Superseded Asmaa Mnebhi 2 participants 4 messages Feb 24, 2023 GPIO

v2 of 5 Superseded Latest is v5 →

lore
Share & tools
lore

Asmaa Mnebhi

author
#0 lore raw

PATCH v2 1/1 gpio: mmio: handle "ngpios" properly in bgpio_init()

bgpio_init() uses "sz" argument to populate ngpio, which is not accurate. Instead, read the "ngpios" property from the DT and if it doesn't exist, use the "sz" argument. With this change, drivers no longer need to overwrite the ngpio variable after calling bgpio_init.

Signed-off-by Asmaa Mnebhi <[email protected]>
---
 drivers/gpio/gpio-mmio.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
drivers/gpio/gpio-mmio.c +4 -1
index d9dff3dc92ae..448fefc4468c 100644
@@ -614,10 +614,13 @@ int bgpio_init(struct gpio_chip *gc, struct device *dev,
 	gc->parent = dev;
 	gc->label = dev_name(dev);
 	gc->base = -1;
-	gc->ngpio = gc->bgpio_bits;
 	gc->request = bgpio_request;
 	gc->be_bits = !!(flags & BGPIOF_BIG_ENDIAN);
 
+	ret = device_property_present(dev, "ngpios");
+	if (!ret)
+		gc->ngpio = gc->bgpio_bits;
+
 	ret = bgpio_setup_io(gc, dat, set, clr, flags);
 	if (ret)
 		return ret;
Signature · 1 line
2.30.1
#1 lore raw
Quoted 5 lines · Asmaa Mnebhi

bgpio_init() uses "sz" argument to populate ngpio, which is not accurate. Instead, read the "ngpios" property from the DT and if it doesn't exist, use the "sz" argument. With this change, drivers no longer need to overwrite the ngpio variable after calling bgpio_init.

...

drivers/gpio/gpio-mmio.c int bgpio_init(struct gpio_chip *gc, struct device *dev, · line 621

Quoted 2 lines
drivers/gpio/gpio-mmio.c +2 -0
+       ret = device_property_present(dev, "ngpios");
+       if (!ret)

ret is not of the correct type for this call.

Why not simply

if (!device_property_present(dev, "ngpios"))

Quoted 1 line

+ gc->ngpio = gc->bgpio_bits;

...

The problem with this change is that you need to provide bgpio_bits.

So, if there is a property when bgpio_bits will be updated?

That's said what you need is something like this:
1) split "ngpios" handling code (lines ~718-744 in gpiolib.c) into a helper function that is available inside drivers/gpio;
2) use it in bgpio_init() by overriding bgpio_bits.

ret = new_helper();
if (ret)

    gc->bgpio_bits = sz * 8;
else
    ... = gc->ngpio;
Signature · 2 lines
With Best Regards,
Andy Shevchenko
author
#2 lore raw
Quoted 29 lines
Quoted 4 lines

bgpio_init() uses "sz" argument to populate ngpio, which is not accurate. Instead, read the "ngpios" property from the DT and if it doesn't exist, use the "sz" argument. With this change, drivers no longer need to overwrite the ngpio variable after calling bgpio_init.

...

drivers/gpio/gpio-mmio.c int bgpio_init(struct gpio_chip *gc, struct device *dev, · line 621

Quoted 2 lines
drivers/gpio/gpio-mmio.c +2 -0
+       ret = device_property_present(dev, "ngpios");
+       if (!ret)

ret is not of the correct type for this call.

Why not simply

if (!device_property_present(dev, "ngpios"))

Quoted 1 line

+ gc->ngpio = gc->bgpio_bits;

...

The problem with this change is that you need to provide bgpio_bits.

So, if there is a property when bgpio_bits will be updated?

That's said what you need is something like this:
1) split "ngpios" handling code (lines ~718-744 in gpiolib.c) into a helper function that is available inside drivers/gpio;
2) use it in bgpio_init() by overriding bgpio_bits.

Quoted 5 lines

ret = new_helper();
if (ret)

    gc->bgpio_bits = sz * 8;
else
    ... = gc->ngpio;

So this new_helper() which reads the ngpios property, would be called from bgpio_init() and From gpiochip_add_data_with_key() correct? Since there are some drivers that don’t use bgpio_init().
Also, shouldn't "gc->bgpio_bits = = sz * 8;" be independent of new_helper() function? "bgpio_bits" is described as "number of register bits used for a generic GPIO i.e. <register width> * 8" which seems different from "ngpio" described as "the number of GPIOs handled by this controller"

#3 lore raw

Fri, Feb 24, 2023 at 09:31:23PM +0000, Asmaa Mnebhi kirjoitti:

...

Quoted 15 lines
Quoted 9 lines

The problem with this change is that you need to provide bgpio_bits.

So, if there is a property when bgpio_bits will be updated?

That's said what you need is something like this:
1) split "ngpios" handling code (lines ~718-744 in gpiolib.c) into a helper function that is available inside drivers/gpio;
2) use it in bgpio_init() by overriding bgpio_bits.

Quoted 5 lines

ret = new_helper();
if (ret)

    gc->bgpio_bits = sz * 8;
else
    ... = gc->ngpio;
Quoted 3 lines

So this new_helper() which reads the ngpios property, would be called from bgpio_init() and From gpiochip_add_data_with_key() correct? Since there are some drivers that don’t use bgpio_init().

Correct.

Quoted 1 line

Also, shouldn't "gc->bgpio_bits = = sz * 8;" be independent of new_helper()

Nope. You need to link them anyway.

Quoted 3 lines

function? "bgpio_bits" is described as "number of register bits used for a generic GPIO i.e. <register width> * 8" which seems different from "ngpio" described as "the number of GPIOs handled by this controller"

But you are right, this should be = round_up(gc->ngpio, 8); to match the logic with sz.

Signature · 2 lines
With Best Regards,
Andy Shevchenko