[v2] gpio: pca953x: do not enable regmap cache when there is no regulator

Commit Message

Bough Chen Nov. 28, 2024, 2 a.m. UTC

From: Haibo Chen <[e-mail]>

Regmap cache mechanism is enabled in default. Thus, IO expander wouldn't
handle GPIO set really before resuming back.

But there are cases need to toggle gpio in NO_IRQ stage.
e.g. To align with PCIe specification, PERST# signal connected on the IO
expander must be toggled during PCIe RC's NO_IRQ_RESUME.

Do not enable the regmap cache when IO expander doesn't have the regulator
during system PM. That means the power of IO expander would be kept on,
and the GPIOs of the IO expander can be toggled really during system PM.

Fixes: b76574300504 ("gpio: pca953x: Restore registers after suspend/resume cycle")
Signed-off-by: Haibo Chen <[e-mail]>
---
Changes for V2:
  correct the commit head, and add fix tag
  fix some typo in the code comment

---
 drivers/gpio/gpio-pca953x.c | 35 ++++++++++++++++++++++++++---------
 1 file changed, 26 insertions(+), 9 deletions(-)

Patch

diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index 272febc3230e..2ef1db58a6a1 100644
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -1040,9 +1040,15 @@  static int pca953x_get_and_enable_regulator(struct pca953x_chip *chip)
 	struct regulator *reg = chip->regulator;
 	int ret;
 
-	reg = devm_regulator_get(dev, "vcc");
-	if (IS_ERR(reg))
-		return dev_err_probe(dev, PTR_ERR(reg), "reg get err\n");
+	reg = devm_regulator_get_optional(dev, "vcc");
+	if (IS_ERR(reg)) {
+		if (PTR_ERR(reg) == -ENODEV) {
+			chip->regulator = NULL;
+			return 0;
+		} else {
+			return dev_err_probe(dev, PTR_ERR(reg), "reg get err\n");
+		}
+	}
 
 	ret = regulator_enable(reg);
 	if (ret)
@@ -1240,11 +1246,20 @@  static int pca953x_suspend(struct device *dev)
 {
 	struct pca953x_chip *chip = dev_get_drvdata(dev);
 
-	pca953x_save_context(chip);
+	/*
+	 * Only save context when regulator is exist,
+	 * if no regulator, power keeps on, can also
+	 * handle gpio related operation.
+	 * e.g. PCIe RC needs to toggle the RST pin in
+	 * NOIRQ resume stage, so can't open regmap
+	 * cache if there is no regulator.
+	 */
+	if (chip->regulator)
+		pca953x_save_context(chip);
 
 	if (atomic_read(&chip->wakeup_path))
 		device_set_wakeup_path(dev);
-	else
+	else if (chip->regulator)
 		regulator_disable(chip->regulator);
 
 	return 0;
@@ -1255,7 +1270,7 @@  static int pca953x_resume(struct device *dev)
 	struct pca953x_chip *chip = dev_get_drvdata(dev);
 	int ret;
 
-	if (!atomic_read(&chip->wakeup_path)) {
+	if (!atomic_read(&chip->wakeup_path) && chip->regulator) {
 		ret = regulator_enable(chip->regulator);
 		if (ret) {
 			dev_err(dev, "Failed to enable regulator: %d\n", ret);
@@ -1263,9 +1278,11 @@  static int pca953x_resume(struct device *dev)
 		}
 	}
 
-	ret = pca953x_restore_context(chip);
-	if (ret)
-		dev_err(dev, "Failed to restore register map: %d\n", ret);
+	if (chip->regulator) {
+		ret = pca953x_restore_context(chip);
+		if (ret)
+			dev_err(dev, "Failed to restore register map: %d\n", ret);
+	}
 
 	return ret;
 }