[PATCH 3/3] pinctrl: exynos: ack level-triggered interrupts before unmasking

[Doug Anderson <dianders@chromium.org>]

A level-triggered interrupt should be acked after the interrupt line
becomes inactive and before it is unmasked, or else another interrupt
will be immediately triggered.  Acking before or after calling the
handler is not enough.

Signed-off-by: Luigi Semenzato <semenzato@chromium.org>
Signed-off-by: Doug Anderson <dianders@chromium.org>
---
 drivers/pinctrl/pinctrl-exynos.c | 42 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/drivers/pinctrl/pinctrl-exynos.c b/drivers/pinctrl/pinctrl-exynos.c
index c0729a3..67b7a27 100644
--- a/drivers/pinctrl/pinctrl-exynos.c
+++ b/drivers/pinctrl/pinctrl-exynos.c
@@ -81,11 +81,32 @@ static void exynos_gpio_irq_unmask(struct irq_data *irqd)
 	struct samsung_pin_bank *bank = irq_data_get_irq_chip_data(irqd);
 	struct samsung_pinctrl_drv_data *d = bank->drvdata;
 	unsigned long reg_mask = d->ctrl->geint_mask + bank->eint_offset;
+	unsigned long reg_con = d->ctrl->geint_con + bank->eint_offset;
+	unsigned int pin = irqd->hwirq;
+	unsigned int shift = EXYNOS_EINT_CON_LEN * pin;
+	unsigned int con, trig_type;
 	unsigned long mask;
 	unsigned long flags;
 
 	spin_lock_irqsave(&bank->slock, flags);
 
+	/*
+	 * Ack level interrupts right before unmask
+	 *
+	 * If we don't do this we'll get a double-interrupt.  Level triggered
+	 * interrupts must not fire an interrupt if the level is not
+	 * _currently_ active, even if it was active while the interrupt was
+	 * masked.
+	 */
+	con = readl(d->virt_base + reg_con);
+	trig_type = (con >> shift) & EXYNOS_EINT_CON_MASK;
+	switch (trig_type) {
+	case EXYNOS_EINT_LEVEL_HIGH:
+	case EXYNOS_EINT_LEVEL_LOW:
+		exynos_gpio_irq_ack(irqd);
+		break;
+	}
+
 	mask = readl(d->virt_base + reg_mask);
 	mask &= ~(1 << irqd->hwirq);
 	writel(mask, d->virt_base + reg_mask);
@@ -299,11 +320,32 @@ static void exynos_wkup_irq_unmask(struct irq_data *irqd)
 	struct samsung_pin_bank *b = irq_data_get_irq_chip_data(irqd);
 	struct samsung_pinctrl_drv_data *d = b->drvdata;
 	unsigned long reg_mask = d->ctrl->weint_mask + b->eint_offset;
+	unsigned long reg_con = d->ctrl->weint_con + b->eint_offset;
+	unsigned int pin = irqd->hwirq;
+	unsigned long shift = EXYNOS_EINT_CON_LEN * pin;
+	unsigned long con, trig_type;
 	unsigned long mask;
 	unsigned long flags;
 
 	spin_lock_irqsave(&b->slock, flags);
 
+	/*
+	 * Ack level interrupts right before unmask
+	 *
+	 * If we don't do this we'll get a double-interrupt.  Level triggered
+	 * interrupts must not fire an interrupt if the level is not
+	 * _currently_ active, even if it was active while the interrupt was
+	 * masked.
+	 */
+	con = readl(d->virt_base + reg_con);
+	trig_type = (con >> shift) & EXYNOS_EINT_CON_MASK;
+	switch (trig_type) {
+	case EXYNOS_EINT_LEVEL_HIGH:
+	case EXYNOS_EINT_LEVEL_LOW:
+		exynos_wkup_irq_ack(irqd);
+		break;
+	}
+
 	mask = readl(d->virt_base + reg_mask);
 	mask &= ~(1 << irqd->hwirq);
 	writel(mask, d->virt_base + reg_mask);
-- 
1.8.3