[v5,1/5] gpiolib: Add support for gpiochipN-based table lookup

Commit Message

Geert Uytterhoeven Feb. 18, 2020, 3:18 p.m. UTC

Currently GPIO controllers can only be referred to by label in GPIO
lookup tables.

Add support for looking them up by "gpiochipN" name, with "N" the
corresponding GPIO device's ID number.

Signed-off-by: Geert Uytterhoeven <[e-mail]>
Reviewed-by: Ulrich Hecht <[e-mail]>
Reviewed-by: Eugeniu Rosca <[e-mail]>
Tested-by: Eugeniu Rosca <[e-mail]>
---
v5:
  - Add Reviewed-by, Tested-by,

v4:
  - Add Reviewed-by,
  - Drop support for legacy sysfs interface based name matching,
  - Replace complex custom matching by a simple additional check in the
    existing gpiochip_match_name() function,
  - Add kerneldoc() for find_chip_by_name(), documenting matching order.

v3:
  - New.
---
 drivers/gpio/gpiolib.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

Comments

Linus Walleij March 12, 2020, 2:23 p.m. UTC | #1

On Tue, Feb 18, 2020 at 4:18 PM Geert Uytterhoeven
<[e-mail]> wrote:

> Currently GPIO controllers can only be referred to by label in GPIO
> lookup tables.
>
> Add support for looking them up by "gpiochipN" name, with "N" the
> corresponding GPIO device's ID number.
>
> Signed-off-by: Geert Uytterhoeven <[e-mail]>
> Reviewed-by: Ulrich Hecht <[e-mail]>
> Reviewed-by: Eugeniu Rosca <[e-mail]>
> Tested-by: Eugeniu Rosca <[e-mail]>

Just like with patch 2/5 I have the same problem here that
the commit message doesn't state the technical reason why
we need to change this and support the device name in these
tables and not just labels.

(Possibly again I will realize it...)

Yours,
Linus Walleij

Geert Uytterhoeven March 17, 2020, 8:41 a.m. UTC | #2

Hi Linus,

On Thu, Mar 12, 2020 at 3:23 PM Linus Walleij <[e-mail]> wrote:
> On Tue, Feb 18, 2020 at 4:18 PM Geert Uytterhoeven
> <[e-mail]> wrote:
>
> > Currently GPIO controllers can only be referred to by label in GPIO
> > lookup tables.
> >
> > Add support for looking them up by "gpiochipN" name, with "N" the
> > corresponding GPIO device's ID number.
> >
> > Signed-off-by: Geert Uytterhoeven <[e-mail]>
> > Reviewed-by: Ulrich Hecht <[e-mail]>
> > Reviewed-by: Eugeniu Rosca <[e-mail]>
> > Tested-by: Eugeniu Rosca <[e-mail]>
>
> Just like with patch 2/5 I have the same problem here that
> the commit message doesn't state the technical reason why
> we need to change this and support the device name in these
> tables and not just labels.

As these "gpiochipN" names are not stable, I will drop this patch, and
the related support.

Gr{oetje,eeting}s,

                        Geert


--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [e-mail]

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Patch

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 4d0106ceeba7bb24..200c2d2be4b78043 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1738,9 +1738,18 @@  static int gpiochip_match_name(struct gpio_chip *chip, void *data)
 {
 	const char *name = data;
 
-	return !strcmp(chip->label, name);
+	return !strcmp(chip->label, name) ||
+	       !strcmp(dev_name(&chip->gpiodev->dev), name);
 }
 
+/**
+ * find_chip_by_name() - Find a specific gpio_chip by name
+ * @name: Name to match
+ *
+ * Return a reference to a gpio_chip that matches the passed name.
+ * This function first tries matching on the gpio_chip's label, followed by
+ * matching on dev_name() of the corresponding gpio_device.
+ */
 static struct gpio_chip *find_chip_by_name(const char *name)
 {
 	return gpiochip_find((void *)name, gpiochip_match_name);