gpio: regmap: Support sparsed fixed direction

On some regmapped GPIOs apparently only a sparser selection of the lines
(not all) are actually fixed direction.

Support this situation by adding an optional bitmap indicating which
GPIOs are actually fixed direction and which are not.

Link: https://lore.kernel.org/linux-gpio/20260501155421.3329862-10-elder@riscstar.com/
Tested-by: Alex Elder <elder@riscstar.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>
Reviewed-by: Michael Walle <mwalle@kernel.org>
Reviewed-by: Alex Elder <elder@riscstar.com>
Link: https://patch.msgid.link/20260511-regmap-gpio-sparse-fixed-dir-v3-1-1429ec453be7@kernel.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>

1 files changed, 33 insertions, 4 deletions

diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
index 9ae4a41a2427..b3b4e77ec147 100644
--- a/drivers/gpio/gpio-regmap.c
+++ b/drivers/gpio/gpio-regmap.c
@@ -31,6 +31,7 @@ struct gpio_regmap {
 	unsigned int reg_clr_base;
 	unsigned int reg_dir_in_base;
 	unsigned int reg_dir_out_base;
+	unsigned long *fixed_direction_mask;
 	unsigned long *fixed_direction_output;
 
 #ifdef CONFIG_REGMAP_IRQ
@@ -138,6 +139,20 @@ static int gpio_regmap_set_with_clear(struct gpio_chip *chip,
 	return regmap_write(gpio->regmap, reg, mask);
 }
 
+static bool gpio_regmap_fixed_direction(struct gpio_regmap *gpio,
+					unsigned int offset)
+{
+	if (!gpio->fixed_direction_output)
+		return false;
+
+	/* In this case only some GPIOs are fixed as input/output */
+	if (gpio->fixed_direction_mask &&
+	    !test_bit(offset, gpio->fixed_direction_mask))
+		return false;
+
+	return true;
+}
+
 static int gpio_regmap_get_direction(struct gpio_chip *chip,
 				     unsigned int offset)
 {
@@ -145,7 +160,7 @@ static int gpio_regmap_get_direction(struct gpio_chip *chip,
 	unsigned int base, val, reg, mask;
 	int invert, ret;
 
-	if (gpio->fixed_direction_output) {
+	if (gpio_regmap_fixed_direction(gpio, offset)) {
 		if (test_bit(offset, gpio->fixed_direction_output))
 			return GPIO_LINE_DIRECTION_OUT;
 		else
@@ -302,12 +317,23 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
 			goto err_free_gpio;
 	}
 
+	if (config->fixed_direction_mask) {
+		gpio->fixed_direction_mask = bitmap_alloc(chip->ngpio,
+							    GFP_KERNEL);
+		if (!gpio->fixed_direction_mask) {
+			ret = -ENOMEM;
+			goto err_free_gpio;
+		}
+		bitmap_copy(gpio->fixed_direction_mask,
+			    config->fixed_direction_mask, chip->ngpio);
+	}
+
 	if (config->fixed_direction_output) {
 		gpio->fixed_direction_output = bitmap_alloc(chip->ngpio,
 							    GFP_KERNEL);
 		if (!gpio->fixed_direction_output) {
 			ret = -ENOMEM;
-			goto err_free_gpio;
+			goto err_free_bitmap_dirmask;
 		}
 		bitmap_copy(gpio->fixed_direction_output,
 			    config->fixed_direction_output, chip->ngpio);
@@ -329,7 +355,7 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
 
 	ret = gpiochip_add_data(chip, gpio);
 	if (ret < 0)
-		goto err_free_bitmap;
+		goto err_free_bitmap_output;
 
 #ifdef CONFIG_REGMAP_IRQ
 	if (config->regmap_irq_chip) {
@@ -355,8 +381,10 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
 
 err_remove_gpiochip:
 	gpiochip_remove(chip);
-err_free_bitmap:
+err_free_bitmap_output:
 	bitmap_free(gpio->fixed_direction_output);
+err_free_bitmap_dirmask:
+	bitmap_free(gpio->fixed_direction_mask);
 err_free_gpio:
 	kfree(gpio);
 	return ERR_PTR(ret);
@@ -376,6 +404,7 @@ void gpio_regmap_unregister(struct gpio_regmap *gpio)
 
 	gpiochip_remove(&gpio->gpio_chip);
 	bitmap_free(gpio->fixed_direction_output);
+	bitmap_free(gpio->fixed_direction_mask);
 	kfree(gpio);
 }
 EXPORT_SYMBOL_GPL(gpio_regmap_unregister);