Re: [PATCH v4 2/2] gpio: add a reusable generic gpio_chip using regmap

From: Pierre-Louis Bossart
Date: Wed May 27 2020 - 20:31:56 EST

Hi Michael,

+struct gpio_regmap_config {
+ÂÂÂ struct device *parent;
+ÂÂÂ struct regmap *regmap;
+ÂÂÂ const char *label;
+ÂÂÂ int ngpio;

could we add a .names field for the gpio_chip, I found this useful for
PCM512x GPIO support, e.g.

Sure, I have the names in the device tree.

But I'd prefer that you'd do a patch on top of this (assuming it is
applied soon), because you can actually test it and there might be
missing more.

I am happy to report that this gpio-regmap worked like a charm for me, after I applied the minor diff below (complete code at

I worked around my previous comments by forcing the GPIO internal routing directly in regmap, and that allowed me to only play with the _set and _dir bases. I see the LEDs and clock selected as before, quite nice indeed.

The chip->label test is probably wrong, since the gpio_chip structure is zeroed out if(!chip->label) is always true so the label is always set to the device name. I don't know what the intent was so just removed that test - maybe the correct test should be if (!config->label) ?

I added the names support as well, and btw I don't understand how one would get them through device tree?

I still have a series of odd warnings I didn't have before:

[ 101.400263] WARNING: CPU: 3 PID: 1129 at drivers/gpio/gpiolib.c:4084 gpiod_set_value+0x3f/0x50

This seems to come from
/* Should be using gpiod_set_value_cansleep() */

so maybe we need an option here as well? Or use a different function?

Anyways, that gpio-regmap does simplify my code a great deal so thanks for this work, much appreciated.

diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
index 3cb0e8493835..678d644a0a4b 100644
--- a/drivers/gpio/gpio-regmap.c
+++ b/drivers/gpio/gpio-regmap.c
@@ -251,10 +251,8 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
chip->ngpio = config->ngpio;
chip->can_sleep = true;

- if (!chip->label)
- chip->label = dev_name(config->parent);
- else
- chip->label = config->label;
+ chip->label = config->label;
+ chip->names = config->names;

chip->get = gpio_regmap_get;
if (gpio->reg_set_base && gpio->reg_clr_base)
diff --git a/include/linux/gpio-regmap.h b/include/linux/gpio-regmap.h
index bbdb2d79ef8f..c1f3e36ebf33 100644
--- a/include/linux/gpio-regmap.h
+++ b/include/linux/gpio-regmap.h
@@ -16,6 +16,7 @@ struct gpio_regmap;
* given, the name of the device is used
* @label: (Optional) Descriptive name for GPIO controller.
* If not given, the name of the device is used.
+ * @names: (Optional) Array of names for gpios
* @ngpio: Number of GPIOs
* @reg_dat_base: (Optional) (in) register base address
* @reg_set_base: (Optional) set register base address
@@ -43,6 +44,7 @@ struct gpio_regmap_config {
struct regmap *regmap;

const char *label;
+ const char *const *names;
int ngpio;

unsigned int reg_dat_base;