gpio: pca953x: Improve bias setting

The commit 15add06 ("gpio: pca953x: add ->set_config implementation")
introduced support for bias setting. However this, due to being half-baked,
brought potential issues:
 - the turning bias via disabling makes the pin floating for a while;
 - once enabled, bias can't be disabled.

Fix all these by adding support for bias disabling and move the disabling
part under the corresponding conditional.

While at it, add support for default setting, since it's cheap to add.

Fixes: 15add06 ("gpio: pca953x: add ->set_config implementation")
Cc: Thomas Petazzoni <[email protected]>
Signed-off-by: Andy Shevchenko <[email protected]>
Signed-off-by: Bartosz Golaszewski <[email protected]>

Author: andy-shev

drivers/gpio/gpio-pca953x.c

@@ -559,21 +559,21 @@ static int pca953x_gpio_set_pull_up_down(struct pca953x_chip *chip,
 
 	mutex_lock(&chip->i2c_lock);
 
-	/* Disable pull-up/pull-down */
-	ret = regmap_write_bits(chip->regmap, pull_en_reg, bit, 0);
-	if (ret)
-		goto exit;
-
 	/* Configure pull-up/pull-down */
 	if (config == PIN_CONFIG_BIAS_PULL_UP)
 		ret = regmap_write_bits(chip->regmap, pull_sel_reg, bit, bit);
 	else if (config == PIN_CONFIG_BIAS_PULL_DOWN)
 		ret = regmap_write_bits(chip->regmap, pull_sel_reg, bit, 0);
+	else
+		ret = 0;
 	if (ret)
 		goto exit;
 
-	/* Enable pull-up/pull-down */
-	ret = regmap_write_bits(chip->regmap, pull_en_reg, bit, bit);
+	/* Disable/Enable pull-up/pull-down */
+	if (config == PIN_CONFIG_BIAS_DISABLE)
+		ret = regmap_write_bits(chip->regmap, pull_en_reg, bit, 0);
+	else
+		ret = regmap_write_bits(chip->regmap, pull_en_reg, bit, bit);
 
 exit:
 	mutex_unlock(&chip->i2c_lock);
@@ -587,7 +587,9 @@ static int pca953x_gpio_set_config(struct gpio_chip *gc, unsigned int offset,
 
 	switch (pinconf_to_config_param(config)) {
 	case PIN_CONFIG_BIAS_PULL_UP:
+	case PIN_CONFIG_BIAS_PULL_PIN_DEFAULT:
 	case PIN_CONFIG_BIAS_PULL_DOWN:
+	case PIN_CONFIG_BIAS_DISABLE:
 		return pca953x_gpio_set_pull_up_down(chip, offset, config);
 	default:
 		return -ENOTSUPP;