[PATCH v3] gpio: mvebu: convert to noirq suspend/resume to prevent interrupt storm on resume

[Rosen Penev <rosenp@gmail.com>]

The driver uses the legacy .suspend/.resume callbacks, but sets
IRQCHIP_MASK_ON_SUSPEND on the irq_chip. During resume, the PM core
runs dpm_resume_noirq() first, which calls irq_pm_resume() to unmask
interrupts, and only then runs dpm_resume() which invokes the driver's
.resume callback to restore GPIO registers (GPIO_IN_POL, GPIO_IO_CONF,
mask registers).

This ordering means interrupts are unmasked while the hardware is still
in its reset state, potentially with incorrect polarities, causing
spurious level-triggered interrupts before local IRQs are re-enabled.

Convert the driver from legacy .suspend/.resume callbacks to noirq
callbacks via dev_pm_ops. The noirq phase runs before resume_device_irqs()
on resume and after suspend_device_irqs() on suspend, ensuring GPIO
registers are restored before interrupts are unmasked.

Assisted-by: LLM
Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 v3: use NOIRQ_SYSTEM_SLEEP_PM_OPS instead.
 v2: add __maybe_unused to fix compilation
 drivers/gpio/gpio-mvebu.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
index 267e6d5bacd0..27894acf8d34 100644
--- a/drivers/gpio/gpio-mvebu.c
+++ b/drivers/gpio/gpio-mvebu.c
@@ -994,9 +994,9 @@ static const struct of_device_id mvebu_gpio_of_match[] = {
 	},
 };
 
-static int mvebu_gpio_suspend(struct platform_device *pdev, pm_message_t state)
+static int mvebu_gpio_suspend(struct device *dev)
 {
-	struct mvebu_gpio_chip *mvchip = platform_get_drvdata(pdev);
+	struct mvebu_gpio_chip *mvchip = dev_get_drvdata(dev);
 	int i;
 
 	regmap_read(mvchip->regs, GPIO_OUT_OFF + mvchip->offset,
@@ -1046,9 +1046,9 @@ static int mvebu_gpio_suspend(struct platform_device *pdev, pm_message_t state)
 	return 0;
 }
 
-static int mvebu_gpio_resume(struct platform_device *pdev)
+static int mvebu_gpio_resume(struct device *dev)
 {
-	struct mvebu_gpio_chip *mvchip = platform_get_drvdata(pdev);
+	struct mvebu_gpio_chip *mvchip = dev_get_drvdata(dev);
 	u32 edge_cache = ~0U, level_cache = ~0U;
 	unsigned long flags;
 	int i;
@@ -1369,13 +1369,16 @@ static int mvebu_gpio_probe(struct platform_device *pdev)
 	return 0;
 }
 
+static const struct dev_pm_ops mvebu_gpio_pm_ops = {
+	NOIRQ_SYSTEM_SLEEP_PM_OPS(mvebu_gpio_suspend, mvebu_gpio_resume)
+};
+
 static struct platform_driver mvebu_gpio_driver = {
 	.driver		= {
 		.name		= "mvebu-gpio",
 		.of_match_table = mvebu_gpio_of_match,
+		.pm		= pm_sleep_ptr(&mvebu_gpio_pm_ops),
 	},
 	.probe		= mvebu_gpio_probe,
-	.suspend        = mvebu_gpio_suspend,
-	.resume         = mvebu_gpio_resume,
 };
 builtin_platform_driver(mvebu_gpio_driver);
-- 
2.55.0