gpio: mcp23s08: Add option to configure IRQ output polarity as active high

Default is active low, but if property is specified in DT set INTPOL flag.

Signed-off-by: Alexander Stein <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

Documentation/devicetree/bindings/gpio/gpio-mcp23s08.txt

···
         occurred on. If it is not set, the interrupt are only generated for the
         bank they belong to.
         On devices with only one interrupt output this property is useless.
+- microchip,irq-active-high: Sets the INTPOL flag in the IOCON register. This
+        configures the IRQ output polarity as active high.
 
 Example I2C (with interrupt):
 gpiom1: gpio@20 {

drivers/gpio/gpio-mcp23s08.c

···
 
 struct mcp23s08 {
 	u8			addr;
+	bool			irq_active_high;
 
 	u16			cache[11];
 	u16			irq_rise;
···
 {
 	struct gpio_chip *chip = &mcp->chip;
 	int err, irq, j;
+	unsigned long irqflags = IRQF_ONESHOT | IRQF_SHARED;
 
 	mutex_init(&mcp->irq_lock);
 
···
 	if (!mcp->irq_domain)
 		return -ENODEV;
 
+	if (mcp->irq_active_high)
+		irqflags |= IRQF_TRIGGER_HIGH;
+	else
+		irqflags |= IRQF_TRIGGER_LOW;
+
 	err = devm_request_threaded_irq(chip->dev, mcp->irq, NULL, mcp23s08_irq,
-					IRQF_TRIGGER_LOW | IRQF_ONESHOT |
-					IRQF_SHARED,
-					dev_name(chip->dev), mcp);
+					irqflags, dev_name(chip->dev), mcp);
 	if (err != 0) {
 		dev_err(chip->dev, "unable to request IRQ#%d: %d\n",
 			mcp->irq, err);
···
 
 	mcp->data = data;
 	mcp->addr = addr;
+	mcp->irq_active_high = false;
 
 	mcp->chip.direction_input = mcp23s08_direction_input;
 	mcp->chip.get = mcp23s08_get;
···
 		goto fail;
 
 	mcp->irq_controller = pdata->irq_controller;
-	if (mcp->irq && mcp->irq_controller && (type == MCP_TYPE_017))
-		mirror = pdata->mirror;
+	if (mcp->irq && mcp->irq_controller) {
+		mcp->irq_active_high = of_property_read_bool(mcp->chip.of_node,
+				"microchip,irq-active-high");
 
-	if ((status & IOCON_SEQOP) || !(status & IOCON_HAEN) || mirror) {
+		if (type == MCP_TYPE_017)
+			mirror = pdata->mirror;
+	}
+
+	if ((status & IOCON_SEQOP) || !(status & IOCON_HAEN) || mirror ||
+	     mcp->irq_active_high) {
 		/* mcp23s17 has IOCON twice, make sure they are in sync */
 		status &= ~(IOCON_SEQOP | (IOCON_SEQOP << 8));
 		status |= IOCON_HAEN | (IOCON_HAEN << 8);
-		status &= ~(IOCON_INTPOL | (IOCON_INTPOL << 8));
+		if (mcp->irq_active_high)
+			status |= IOCON_INTPOL | (IOCON_INTPOL << 8);
+		else
+			status &= ~(IOCON_INTPOL | (IOCON_INTPOL << 8));
+
 		if (mirror)
 			status |= IOCON_MIRROR | (IOCON_MIRROR << 8);