gpio: em: Add pinctrl support

Register the GPIO pin range, and request and free GPIO pins using the
pinctrl API. The pctl_name platform data member should be used by
platform devices to point out which pinctrl device to use.

Follows same style as "dc3465a gpio-rcar: Add pinctrl support",
by Laurent Pinchart, thanks to him.

Signed-off-by: Magnus Damm <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

drivers/gpio/gpio-em.c

···
 #include <linux/gpio.h>
 #include <linux/slab.h>
 #include <linux/module.h>
+#include <linux/pinctrl/consumer.h>
 #include <linux/platform_data/gpio-em.h>
 
 struct em_gio_priv {
···
 	return irq_create_mapping(gpio_to_priv(chip)->irq_domain, offset);
 }
 
+static int em_gio_request(struct gpio_chip *chip, unsigned offset)
+{
+	return pinctrl_request_gpio(chip->base + offset);
+}
+
+static void em_gio_free(struct gpio_chip *chip, unsigned offset)
+{
+	pinctrl_free_gpio(chip->base + offset);
+
+	/* Set the GPIO as an input to ensure that the next GPIO request won't
+	* drive the GPIO pin as an output.
+	*/
+	em_gio_direction_input(chip, offset);
+}
+
 static int em_gio_irq_domain_map(struct irq_domain *h, unsigned int virq,
 				 irq_hw_number_t hw)
 {
···
 	gpio_chip->direction_output = em_gio_direction_output;
 	gpio_chip->set = em_gio_set;
 	gpio_chip->to_irq = em_gio_to_irq;
+	gpio_chip->request = em_gio_request;
+	gpio_chip->free = em_gio_free;
 	gpio_chip->label = name;
 	gpio_chip->owner = THIS_MODULE;
 	gpio_chip->base = pdata->gpio_base;
···
 	if (ret) {
 		dev_err(&pdev->dev, "failed to add GPIO controller\n");
 		goto err1;
+	}
+
+	if (pdata->pctl_name) {
+		ret = gpiochip_add_pin_range(gpio_chip, pdata->pctl_name, 0,
+					     gpio_chip->base, gpio_chip->ngpio);
+		if (ret < 0)
+			dev_warn(&pdev->dev, "failed to add pin range\n");
 	}
 	return 0;
 

include/linux/platform_data/gpio-em.h

···
 	unsigned int gpio_base;
 	unsigned int irq_base;
 	unsigned int number_of_pins;
+	const char *pctl_name;
 };
 
 #endif /* __GPIO_EM_H__ */