[v3,3/7] gpiolib: Add support for GPIO line table lookup
diff mbox series

Message ID 20191127084253.16356-4-geert+renesas@glider.be
State New
Headers show
Series
  • gpio: Add GPIO Aggregator/Repeater
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Commit Message

Geert Uytterhoeven Nov. 27, 2019, 8:42 a.m. UTC
Currently GPIOs can only be referred to by GPIO controller and offset in
GPIO lookup tables.

Add support for looking them up by line name.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
If this is rejected, the GPIO Aggregator documentation and code must be
updated.

v3:
  - New.
---
 drivers/gpio/gpiolib.c       | 12 ++++++++++++
 include/linux/gpio/machine.h |  2 +-
 2 files changed, 13 insertions(+), 1 deletion(-)

Comments

Ulrich Hecht Nov. 28, 2019, 3:39 a.m. UTC | #1
> On November 27, 2019 at 9:42 AM Geert Uytterhoeven <geert+renesas@glider.be> wrote:
> 
> 
> Currently GPIOs can only be referred to by GPIO controller and offset in
> GPIO lookup tables.
> 
> Add support for looking them up by line name.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
> If this is rejected, the GPIO Aggregator documentation and code must be
> updated.
> 
> v3:
>   - New.
> ---
>  drivers/gpio/gpiolib.c       | 12 ++++++++++++
>  include/linux/gpio/machine.h |  2 +-
>  2 files changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index d24a3d79dcfe69ad..cb608512ad6bbded 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -4475,6 +4475,18 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
>  		if (p->con_id && (!con_id || strcmp(p->con_id, con_id)))
>  			continue;
>  
> +		if (p->chip_hwnum == (u16)-1) {
> +			desc = gpio_name_to_desc(p->chip_label);
> +			if (desc) {
> +				*flags = p->flags;
> +				return desc;
> +			}
> +
> +			dev_warn(dev, "cannot find GPIO line %s, deferring\n",
> +				 p->chip_label);
> +			return ERR_PTR(-EPROBE_DEFER);
> +		}
> +
>  		chip = find_chip_by_name(p->chip_label);
>  
>  		if (!chip) {
> diff --git a/include/linux/gpio/machine.h b/include/linux/gpio/machine.h
> index 1ebe5be05d5f81fa..84c1c097e55eefaf 100644
> --- a/include/linux/gpio/machine.h
> +++ b/include/linux/gpio/machine.h
> @@ -31,7 +31,7 @@ enum gpio_lookup_flags {
>   */
>  struct gpiod_lookup {
>  	const char *chip_label;
> -	u16 chip_hwnum;
> +	u16 chip_hwnum;			/* if -1, chip_label is named line */

The magic number "-1" might deserve a #define.

>  	const char *con_id;
>  	unsigned int idx;
>  	unsigned long flags;
> -- 
> 2.17.1
>

With or without #define,
Reviewed-by: Ulrich Hecht <uli+renesas@fpond.eu>

CU
Uli
Linus Walleij Dec. 12, 2019, 1:40 p.m. UTC | #2
On Wed, Nov 27, 2019 at 9:43 AM Geert Uytterhoeven
<geert+renesas@glider.be> wrote:

> Currently GPIOs can only be referred to by GPIO controller and offset in
> GPIO lookup tables.
>
> Add support for looking them up by line name.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

OK I see what you want to do...

> +               if (p->chip_hwnum == (u16)-1) {

If you want to use this then use:

if (p->chip_hwnum == U16_MAX)

from <linux/limits.h>

> +                       desc = gpio_name_to_desc(p->chip_label);
> +                       if (desc) {
> +                               *flags = p->flags;
> +                               return desc;
> +                       }
> +
> +                       dev_warn(dev, "cannot find GPIO line %s, deferring\n",
> +                                p->chip_label);
> +                       return ERR_PTR(-EPROBE_DEFER);
> +               }
> +
>                 chip = find_chip_by_name(p->chip_label);
>
>                 if (!chip) {
> diff --git a/include/linux/gpio/machine.h b/include/linux/gpio/machine.h
> index 1ebe5be05d5f81fa..84c1c097e55eefaf 100644
> --- a/include/linux/gpio/machine.h
> +++ b/include/linux/gpio/machine.h
> @@ -31,7 +31,7 @@ enum gpio_lookup_flags {
>   */
>  struct gpiod_lookup {
>         const char *chip_label;
> -       u16 chip_hwnum;
> +       u16 chip_hwnum;                 /* if -1, chip_label is named line */

/* if U16_MAX then chip_label is the named line we are looking for */

But the member name "chip_label" is completely abused with this
setup, it should then be renamed as part of the patch set to something
like chip_label_or_line_name so it is clear what it is or
just name it "const char *key".

But I'm not entirely convinced about reusing the existing
struct gpio_lookup for this.

What about constructing a new lookup struct specifically for this?
I understand it is more work, but will that not be more
maintainable and readable?

Yours,
Linus Walleij

Patch
diff mbox series

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index d24a3d79dcfe69ad..cb608512ad6bbded 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -4475,6 +4475,18 @@  static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
 		if (p->con_id && (!con_id || strcmp(p->con_id, con_id)))
 			continue;
 
+		if (p->chip_hwnum == (u16)-1) {
+			desc = gpio_name_to_desc(p->chip_label);
+			if (desc) {
+				*flags = p->flags;
+				return desc;
+			}
+
+			dev_warn(dev, "cannot find GPIO line %s, deferring\n",
+				 p->chip_label);
+			return ERR_PTR(-EPROBE_DEFER);
+		}
+
 		chip = find_chip_by_name(p->chip_label);
 
 		if (!chip) {
diff --git a/include/linux/gpio/machine.h b/include/linux/gpio/machine.h
index 1ebe5be05d5f81fa..84c1c097e55eefaf 100644
--- a/include/linux/gpio/machine.h
+++ b/include/linux/gpio/machine.h
@@ -31,7 +31,7 @@  enum gpio_lookup_flags {
  */
 struct gpiod_lookup {
 	const char *chip_label;
-	u16 chip_hwnum;
+	u16 chip_hwnum;			/* if -1, chip_label is named line */
 	const char *con_id;
 	unsigned int idx;
 	unsigned long flags;