gpio: merrifield: Add support of ACPI enabled platforms

The driver needs the pin control device name for ACPI.

We are looking through ACPI namespace and return first found device
based on ACPI HID for Intel Merrifield FLIS (pin control device).
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/gpio/gpio-merrifield.c

@@ -9,6 +9,7 @@
  * published by the Free Software Foundation.
  */
 
+#include <linux/acpi.h>
 #include <linux/bitops.h>
 #include <linux/gpio/driver.h>
 #include <linux/init.h>
@@ -380,9 +381,16 @@ static void mrfld_irq_init_hw(struct mrfld_gpio *priv)
 	}
 }
 
+static const char *mrfld_gpio_get_pinctrl_dev_name(void)
+{
+	const char *dev_name = acpi_dev_get_first_match_name("INTC1002", NULL, -1);
+	return dev_name ? dev_name : "pinctrl-merrifield";
+}
+
 static int mrfld_gpio_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 {
 	const struct mrfld_gpio_pinrange *range;
+	const char *pinctrl_dev_name;
 	struct mrfld_gpio *priv;
 	u32 gpio_base, irq_base;
 	void __iomem *base;
@@ -439,10 +447,11 @@ static int mrfld_gpio_probe(struct pci_dev *pdev, const struct pci_device_id *id
 		return retval;
 	}
 
+	pinctrl_dev_name = mrfld_gpio_get_pinctrl_dev_name();
 	for (i = 0; i < ARRAY_SIZE(mrfld_gpio_ranges); i++) {
 		range = &mrfld_gpio_ranges[i];
 		retval = gpiochip_add_pin_range(&priv->chip,
-						"pinctrl-merrifield",
+						pinctrl_dev_name,
 						range->gpio_base,
 						range->pin_base,
 						range->npins);