gpio: stmpe: forbid unused lines to be mapped as IRQs

Exploit the new mechanism for masking off disallowed IRQs
added by Mika Westerberg to properly manage the STMPE
"norequest mask" to disallow also mapping said lines as
IRQs.
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-stmpe.c

@@ -13,6 +13,7 @@
 #include <linux/of.h>
 #include <linux/mfd/stmpe.h>
 #include <linux/seq_file.h>
+#include <linux/bitops.h>
 
 /*
  * These registers are modified under the irq bus lock and cached to avoid
@@ -449,6 +450,8 @@ static int stmpe_gpio_probe(struct platform_device *pdev)
 
 	of_property_read_u32(np, "st,norequest-mask",
 			&stmpe_gpio->norequest_mask);
+	if (stmpe_gpio->norequest_mask)
+		stmpe_gpio->chip.irq_need_valid_mask = true;
 
 	if (irq < 0)
 		dev_info(&pdev->dev,
@@ -473,6 +476,14 @@ static int stmpe_gpio_probe(struct platform_device *pdev)
 			dev_err(&pdev->dev, "unable to get irq: %d\n", ret);
 			goto out_disable;
 		}
+		if (stmpe_gpio->norequest_mask) {
+			int i;
+
+			/* Forbid unused lines to be mapped as IRQs */
+			for (i = 0; i < sizeof(u32); i++)
+				if (stmpe_gpio->norequest_mask & BIT(i))
+					clear_bit(i, stmpe_gpio->chip.irq_valid_mask);
+		}
 		ret =  gpiochip_irqchip_add(&stmpe_gpio->chip,
 					    &stmpe_gpio_irq_chip,
 					    0,