[SRU][J:linux-bluefield][PATCH v1 3/3] gpio: mlxbf3: Support shutdown() function

[David Thompson]

From: Asmaa Mnebhi <asmaa at nvidia.com>

BugLink: https://bugs.launchpad.net/bugs/2109756

During Linux graceful reboot, the GPIO interrupts are not disabled.
Since the drivers are not removed during graceful reboot,
the logic to call mlxbf3_gpio_irq_disable() is not triggered.
Interrupts that remain enabled can cause issues on subsequent boots.

For example, the mlxbf-gige driver contains PHY logic to bring up the link.
If the gpio-mlxbf3 driver loads first, the mlxbf-gige driver
will use a GPIO interrupt to bring up the link.
Otherwise, it will use polling.
The next time Linux boots and loads the drivers in this order, we encounter the issue:
- mlxbf-gige loads first and uses polling while the GPIO10
  interrupt is still enabled from the previous boot. So if
  the interrupt triggers, there is nothing to clear it.
- gpio-mlxbf3 loads.
- i2c-mlxbf loads. The interrupt doesn't trigger for I2C
  because it is shared with the GPIO interrupt line which
  was not cleared.

The solution is to add a shutdown function to the GPIO driver to clear and disable
all interrupts. Also clear the interrupt after disabling it in mlxbf3_gpio_irq_disable().

Fixes: 38a700efc510 ("gpio: mlxbf3: Add gpio driver support")
Signed-off-by: Asmaa Mnebhi <asmaa at nvidia.com>
Reviewed-by: David Thompson <davthompson at nvidia.com>
Reviewed-by: Andy Shevchenko <andy at kernel.org>
Reviewed-by: Linus Walleij <linus.walleij at linaro.org>
Link: https://lore.kernel.org/r/20240611171509.22151-1-asmaa@nvidia.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski at linaro.org>
(cherry picked from commit aad41832326723627ad8ac9ee8a543b6dca4454d)
Signed-off-by: David Thompson <davthompson at nvidia.com>
Reviewed-by: Asmaa Mnebhi <asmaa at nvidia.com>
---
 drivers/gpio/gpio-mlxbf3.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/gpio/gpio-mlxbf3.c b/drivers/gpio/gpio-mlxbf3.c
index 8bc56fc9f725..e3c708cef2a8 100644
--- a/drivers/gpio/gpio-mlxbf3.c
+++ b/drivers/gpio/gpio-mlxbf3.c
@@ -39,6 +39,8 @@
 #define MLXBF_GPIO_CAUSE_OR_EVTEN0        0x14
 #define MLXBF_GPIO_CAUSE_OR_CLRCAUSE      0x18
 
+#define MLXBF_GPIO_CLR_ALL_INTS           GENMASK(31, 0)
+
 struct mlxbf3_gpio_context {
 	struct gpio_chip gc;
 
@@ -85,6 +87,8 @@ static void mlxbf3_gpio_irq_disable(struct irq_data *irqd)
 	val = readl(gs->gpio_cause_io + MLXBF_GPIO_CAUSE_OR_EVTEN0);
 	val &= ~BIT(offset);
 	writel(val, gs->gpio_cause_io + MLXBF_GPIO_CAUSE_OR_EVTEN0);
+
+	writel(BIT(offset), gs->gpio_cause_io + MLXBF_GPIO_CAUSE_OR_CLRCAUSE);
 	raw_spin_unlock_irqrestore(&gs->gc.bgpio_lock, flags);
 
 	gpiochip_disable_irq(gc, offset);
@@ -269,6 +273,15 @@ static int mlxbf3_gpio_probe(struct platform_device *pdev)
 	return 0;
 }
 
+static void mlxbf3_gpio_shutdown(struct platform_device *pdev)
+{
+	struct mlxbf3_gpio_context *gs = platform_get_drvdata(pdev);
+
+	/* Disable and clear all interrupts */
+	writel(0, gs->gpio_cause_io + MLXBF_GPIO_CAUSE_OR_EVTEN0);
+	writel(MLXBF_GPIO_CLR_ALL_INTS, gs->gpio_cause_io + MLXBF_GPIO_CAUSE_OR_CLRCAUSE);
+}
+
 static const struct acpi_device_id mlxbf3_gpio_acpi_match[] = {
 	{ "MLNXBF33", 0 },
 	{}
@@ -281,6 +294,7 @@ static struct platform_driver mlxbf3_gpio_driver = {
 		.acpi_match_table = mlxbf3_gpio_acpi_match,
 	},
 	.probe    = mlxbf3_gpio_probe,
+	.shutdown = mlxbf3_gpio_shutdown,
 };
 module_platform_driver(mlxbf3_gpio_driver);
 
-- 
2.43.2