pinctrl: add pin list based GPIO ranges

Traditionally, GPIO ranges are based on consecutive ranges of both GPIO
and pin numbers. This patch allows for GPIO ranges with arbitrary lists
of pin numbers.
Signed-off-by: Christian Ruppert <christian.ruppert@abilis.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/core.c

@@ -282,6 +282,29 @@ static int pinctrl_register_pins(struct pinctrl_dev *pctldev,
 	return 0;
 }
 
+/**
+ * gpio_to_pin() - GPIO range GPIO number to pin number translation
+ * @range: GPIO range used for the translation
+ * @gpio: gpio pin to translate to a pin number
+ *
+ * Finds the pin number for a given GPIO using the specified GPIO range
+ * as a base for translation. The distinction between linear GPIO ranges
+ * and pin list based GPIO ranges is managed correctly by this function.
+ *
+ * This function assumes the gpio is part of the specified GPIO range, use
+ * only after making sure this is the case (e.g. by calling it on the
+ * result of successful pinctrl_get_device_gpio_range calls)!
+ */
+static inline int gpio_to_pin(struct pinctrl_gpio_range *range,
+				unsigned int gpio)
+{
+	unsigned int offset = gpio - range->base;
+	if (range->pins)
+		return range->pins[offset];
+	else
+		return range->pin_base + offset;
+}
+
 /**
  * pinctrl_match_gpio_range() - check if a certain GPIO pin is in range
  * @pctldev: pin controller device to check
@@ -448,8 +471,14 @@ pinctrl_find_gpio_range_from_pin(struct pinctrl_dev *pctldev,
 	/* Loop over the ranges */
 	list_for_each_entry(range, &pctldev->gpio_ranges, node) {
 		/* Check if we're in the valid range */
-		if (pin >= range->pin_base &&
-		    pin < range->pin_base + range->npins) {
+		if (range->pins) {
+			int a;
+			for (a = 0; a < range->npins; a++) {
+				if (range->pins[a] == pin)
+					return range;
+			}
+		} else if (pin >= range->pin_base &&
+			   pin < range->pin_base + range->npins) {
 			mutex_unlock(&pctldev->mutex);
 			return range;
 		}
@@ -529,7 +558,7 @@ int pinctrl_request_gpio(unsigned gpio)
 	}
 
 	/* Convert to the pin controllers number space */
-	pin = gpio - range->base + range->pin_base;
+	pin = gpio_to_pin(range, gpio);
 
 	ret = pinmux_request_gpio(pctldev, range, pin, gpio);
 
@@ -559,7 +588,7 @@ void pinctrl_free_gpio(unsigned gpio)
 	mutex_lock(&pctldev->mutex);
 
 	/* Convert to the pin controllers number space */
-	pin = gpio - range->base + range->pin_base;
+	pin = gpio_to_pin(range, gpio);
 
 	pinmux_free_gpio(pctldev, pin, range);
 
@@ -582,7 +611,7 @@ static int pinctrl_gpio_direction(unsigned gpio, bool input)
 	mutex_lock(&pctldev->mutex);
 
 	/* Convert to the pin controllers number space */
-	pin = gpio - range->base + range->pin_base;
+	pin = gpio_to_pin(range, gpio);
 	ret = pinmux_gpio_direction(pctldev, range, pin, input);
 
 	mutex_unlock(&pctldev->mutex);
@@ -1349,11 +1378,21 @@ static int pinctrl_gpioranges_show(struct seq_file *s, void *what)
 
 	/* Loop over the ranges */
 	list_for_each_entry(range, &pctldev->gpio_ranges, node) {
-		seq_printf(s, "%u: %s GPIOS [%u - %u] PINS [%u - %u]\n",
-			   range->id, range->name,
-			   range->base, (range->base + range->npins - 1),
-			   range->pin_base,
-			   (range->pin_base + range->npins - 1));
+		if (range->pins) {
+			int a;
+			seq_printf(s, "%u: %s GPIOS [%u - %u] PINS {",
+				range->id, range->name,
+				range->base, (range->base + range->npins - 1));
+			for (a = 0; a < range->npins - 1; a++)
+				seq_printf(s, "%u, ", range->pins[a]);
+			seq_printf(s, "%u}\n", range->pins[a]);
+		}
+		else
+			seq_printf(s, "%u: %s GPIOS [%u - %u] PINS [%u - %u]\n",
+				range->id, range->name,
+				range->base, (range->base + range->npins - 1),
+				range->pin_base,
+				(range->pin_base + range->npins - 1));
 	}
 
 	mutex_unlock(&pctldev->mutex);

include/linux/pinctrl/pinctrl.h

@@ -49,7 +49,8 @@ struct pinctrl_pin_desc {
  * @name: a name for the chip in this range
  * @id: an ID number for the chip in this range
  * @base: base offset of the GPIO range
- * @pin_base: base pin number of the GPIO range
+ * @pin_base: base pin number of the GPIO range if pins != NULL
+ * @pins: enumeration of pins in GPIO range or NULL
  * @npins: number of pins in the GPIO range, including the base number
  * @gc: an optional pointer to a gpio_chip
  */
@@ -59,6 +60,7 @@ struct pinctrl_gpio_range {
 	unsigned int id;
 	unsigned int base;
 	unsigned int pin_base;
+	unsigned const *pins;
 	unsigned int npins;
 	struct gpio_chip *gc;
 };