pinctrl: stm32: Add level interrupt support to gpio irq chip

GPIO hardware block is directly linked to EXTI block but EXTI handles
external interrupts only on edge. To be able to handle GPIO interrupt on
level a "hack" is done in gpio irq chip: parent interrupt (exti irq chip)
is retriggered following interrupt type and gpio line value.

Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Tested-by: Marek Vasut <marex@denx.de>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20200219143229.18084-3-alexandre.torgue@st.com

drivers/pinctrl/stm32/pinctrl-stm32.c

@@ -92,6 +92,7 @@ struct stm32_gpio_bank {
 	u32 bank_nr;
 	u32 bank_ioport_nr;
 	u32 pin_backup[STM32_GPIO_PINS_PER_BANK];
+	u8 irq_type[STM32_GPIO_PINS_PER_BANK];
 };
 
 struct stm32_pinctrl {
@@ -303,6 +304,46 @@ static const struct gpio_chip stm32_gpio_template = {
 	.get_direction		= stm32_gpio_get_direction,
 };
 
+void stm32_gpio_irq_eoi(struct irq_data *d)
+{
+	struct stm32_gpio_bank *bank = d->domain->host_data;
+	int level;
+
+	irq_chip_eoi_parent(d);
+
+	/* If level interrupt type then retrig */
+	level = stm32_gpio_get(&bank->gpio_chip, d->hwirq);
+	if ((level == 0 && bank->irq_type[d->hwirq] == IRQ_TYPE_LEVEL_LOW) ||
+	    (level == 1 && bank->irq_type[d->hwirq] == IRQ_TYPE_LEVEL_HIGH))
+		irq_chip_retrigger_hierarchy(d);
+};
+
+static int stm32_gpio_set_type(struct irq_data *d, unsigned int type)
+{
+	struct stm32_gpio_bank *bank = d->domain->host_data;
+	u32 parent_type;
+
+	switch (type) {
+	case IRQ_TYPE_EDGE_RISING:
+	case IRQ_TYPE_EDGE_FALLING:
+	case IRQ_TYPE_EDGE_BOTH:
+		parent_type = type;
+		break;
+	case IRQ_TYPE_LEVEL_HIGH:
+		parent_type = IRQ_TYPE_EDGE_RISING;
+		break;
+	case IRQ_TYPE_LEVEL_LOW:
+		parent_type = IRQ_TYPE_EDGE_FALLING;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	bank->irq_type[d->hwirq] = type;
+
+	return irq_chip_set_type_parent(d, parent_type);
+};
+
 static int stm32_gpio_irq_request_resources(struct irq_data *irq_data)
 {
 	struct stm32_gpio_bank *bank = irq_data->domain->host_data;
@@ -332,11 +373,11 @@ static void stm32_gpio_irq_release_resources(struct irq_data *irq_data)
 
 static struct irq_chip stm32_gpio_irq_chip = {
 	.name		= "stm32gpio",
-	.irq_eoi	= irq_chip_eoi_parent,
+	.irq_eoi	= stm32_gpio_irq_eoi,
 	.irq_ack	= irq_chip_ack_parent,
 	.irq_mask	= irq_chip_mask_parent,
 	.irq_unmask	= irq_chip_unmask_parent,
-	.irq_set_type	= irq_chip_set_type_parent,
+	.irq_set_type	= stm32_gpio_set_type,
 	.irq_set_wake	= irq_chip_set_wake_parent,
 	.irq_request_resources = stm32_gpio_irq_request_resources,
 	.irq_release_resources = stm32_gpio_irq_release_resources,