linux-kernel - [PATCH v2 2/2] gpio: cadence: Add support for edge-triggered interrupts

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Message-Id: <20260109-axiado-ax3000-cadence-gpio-support-v2-2-fc1e28edf68a@axiado.com>
Date: Fri, 09 Jan 2026 01:26:07 -0800
From: Swark Yang <syang@...ado.com>
To: Linus Walleij <linus.walleij@...aro.org>, 
 Bartosz Golaszewski <brgl@...nel.org>
Cc: linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
 openbmc@...ts.ozlabs.org, Swark Yang <syang@...ado.com>, 
 Tzu-Hao Wei <twei@...ado.com>, Linus Walleij <linusw@...nel.org>
Subject: [PATCH v2 2/2] gpio: cadence: Add support for edge-triggered
 interrupts

From: Tzu-Hao Wei <twei@...ado.com>

The Cadence GPIO controller (CDNS IP6508) supports edge-triggered
interrupts (rising, falling, and both) via IRQ_TYPE, IRQ_VALUE,
and IRQ_ANY_EDGE registers. This commit enables support for these
modes in cdns_gpio_irq_set_type().

Although the interrupt status register is cleared on read and lacks
per-pin acknowledgment, the driver already handles this safely by
reading the ISR once and dispatching all pending interrupts immediately.
This allows edge IRQs to be used reliably in controlled environments.

Signed-off-by: Tzu-Hao Wei <twei@...ado.com>
Reviewed-by: Linus Walleij <linusw@...nel.org>
Signed-off-by: Swark Yang <syang@...ado.com>
---
 drivers/gpio/gpio-cadence.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpio-cadence.c b/drivers/gpio/gpio-cadence.c
index 85aef54d0aec..d7790fc35c22 100644
--- a/drivers/gpio/gpio-cadence.c
+++ b/drivers/gpio/gpio-cadence.c
@@ -98,6 +98,7 @@ static int cdns_gpio_irq_set_type(struct irq_data *d, unsigned int type)
 	struct cdns_gpio_chip *cgpio = gpiochip_get_data(chip);
 	u32 int_value;
 	u32 int_type;
+	u32 int_any;
 	u32 mask = BIT(d->hwirq);
 	int ret = 0;
 
@@ -105,24 +106,35 @@ static int cdns_gpio_irq_set_type(struct irq_data *d, unsigned int type)
 
 	int_value = ioread32(cgpio->regs + CDNS_GPIO_IRQ_VALUE) & ~mask;
 	int_type = ioread32(cgpio->regs + CDNS_GPIO_IRQ_TYPE) & ~mask;
-
 	/*
-	 * The GPIO controller doesn't have an ACK register.
-	 * All interrupt statuses are cleared on a status register read.
-	 * Don't support edge interrupts for now.
+	 * Interrupt polarity and trigger behaviour is configured like this:
+	 *
+	 * (type, value)
+	 * (0, 0) = Falling edge triggered
+	 * (0, 1) = Rising edge triggered
+	 * (1, 0) = Low level triggered
+	 * (1, 1) = High level triggered
 	 */
+	int_any = ioread32(cgpio->regs + CDNS_GPIO_IRQ_ANY_EDGE) & ~mask;
 
 	if (type == IRQ_TYPE_LEVEL_HIGH) {
 		int_type |= mask;
 		int_value |= mask;
 	} else if (type == IRQ_TYPE_LEVEL_LOW) {
 		int_type |= mask;
+	} else if (type == IRQ_TYPE_EDGE_RISING) {
+		int_value |= mask;
+	} else if (type == IRQ_TYPE_EDGE_FALLING) {
+		/* edge trigger, int_value remains cleared for falling */
+	} else if (type == IRQ_TYPE_EDGE_BOTH) {
+		int_any |= mask;
 	} else {
 		return -EINVAL;
 	}
 
 	iowrite32(int_value, cgpio->regs + CDNS_GPIO_IRQ_VALUE);
 	iowrite32(int_type, cgpio->regs + CDNS_GPIO_IRQ_TYPE);
+	iowrite32(int_any, cgpio->regs + CDNS_GPIO_IRQ_ANY_EDGE);
 
 	return ret;
 }

-- 
2.34.1