gpiolib: Get rid of never false gpio_is_valid() calls

In the cases when gpio_is_valid() is called with unsigned parameter
the result is always true in the GPIO library code, hence the check
for false won't ever be true. Get rid of such calls.

While at it, move GPIO device base to be unsigned to clearly show
it won't ever be negative. This requires a new definition for the
maximum GPIO number in the system.

Signed-off-by: Andy Shevchenko <[e-mail]>
Reviewed-by: Linus Walleij <[e-mail]>
Signed-off-by: Bartosz Golaszewski <[e-mail]>

drivers/gpio/gpiolib-legacy.c

···
 	struct gpio_desc *desc;
 	int err;
 
-	desc = gpio_to_desc(gpio);
-
 	/* Compatibility: assume unavailable "valid" GPIOs will appear later */
-	if (!desc && gpio_is_valid(gpio))
+	desc = gpio_to_desc(gpio);
+	if (!desc)
 		return -EPROBE_DEFER;
 
 	err = gpiod_request(desc, label);
···
  */
 int gpio_request(unsigned gpio, const char *label)
 {
-	struct gpio_desc *desc = gpio_to_desc(gpio);
+	struct gpio_desc *desc;
 
 	/* Compatibility: assume unavailable "valid" GPIOs will appear later */
-	if (!desc && gpio_is_valid(gpio))
+	desc = gpio_to_desc(gpio);
+	if (!desc)
 		return -EPROBE_DEFER;
 
 	return gpiod_request(desc, label);

drivers/gpio/gpiolib-sysfs.c

···
 {
 	const struct gpio_device *gdev = dev_get_drvdata(dev);
 
-	return sysfs_emit(buf, "%d\n", gdev->base);
+	return sysfs_emit(buf, "%u\n", gdev->base);
 }
 static DEVICE_ATTR_RO(base);
 

drivers/gpio/gpiolib.c

···
 		}
 	}
 
-	if (!gpio_is_valid(gpio))
-		pr_warn("invalid GPIO %d\n", gpio);
-
 	return NULL;
 }
 EXPORT_SYMBOL_GPL(gpio_to_desc);
···
 EXPORT_SYMBOL_GPL(gpio_device_get_chip);
 
 /* dynamic allocation of GPIOs, e.g. on a hotplugged device */
-static int gpiochip_find_base_unlocked(int ngpio)
+static int gpiochip_find_base_unlocked(u16 ngpio)
 {
+	unsigned int base = GPIO_DYNAMIC_BASE;
 	struct gpio_device *gdev;
-	int base = GPIO_DYNAMIC_BASE;
 
 	list_for_each_entry_srcu(gdev, &gpio_devices, list,
 				 lockdep_is_held(&gpio_devices_lock)) {
···
 		base = gdev->base + gdev->ngpio;
 		if (base < GPIO_DYNAMIC_BASE)
 			base = GPIO_DYNAMIC_BASE;
+		if (base > GPIO_DYNAMIC_MAX - ngpio)
+			break;
 	}
 
-	if (gpio_is_valid(base)) {
+	if (base <= GPIO_DYNAMIC_MAX - ngpio) {
 		pr_debug("%s: found new base at %d\n", __func__, base);
 		return base;
 	} else {
···
 	if (ret)
 		goto err_remove_device;
 
-	dev_dbg(&gdev->dev, "registered GPIOs %d to %d on %s\n", gdev->base,
+	dev_dbg(&gdev->dev, "registered GPIOs %u to %u on %s\n", gdev->base,
 		gdev->base + gdev->ngpio - 1, gdev->label);
 
 	return 0;
···
 			value = gpio_chip_get_value(gc, desc);
 			is_irq = test_bit(FLAG_USED_AS_IRQ, &desc->flags);
 			active_low = test_bit(FLAG_ACTIVE_LOW, &desc->flags);
-			seq_printf(s, " gpio-%-3d (%-20.20s|%-20.20s) %s %s %s%s\n",
+			seq_printf(s, " gpio-%-3u (%-20.20s|%-20.20s) %s %s %s%s\n",
 				   gpio, desc->name ?: "", gpiod_get_label(desc),
 				   is_out ? "out" : "in ",
 				   value >= 0 ? (value ? "hi" : "lo") : "?  ",
 				   is_irq ? "IRQ " : "",
 				   active_low ? "ACTIVE LOW" : "");
 		} else if (desc->name) {
-			seq_printf(s, " gpio-%-3d (%-20.20s)\n", gpio, desc->name);
+			seq_printf(s, " gpio-%-3u (%-20.20s)\n", gpio, desc->name);
 		}
 
 		gpio++;
···
 		return 0;
 	}
 
-	seq_printf(s, "%s%s: GPIOs %d-%d", priv->newline ? "\n" : "",
+	seq_printf(s, "%s%s: GPIOs %u-%u", priv->newline ? "\n" : "",
 		   dev_name(&gdev->dev),
 		   gdev->base, gdev->base + gdev->ngpio - 1);
 	parent = gc->parent;

drivers/gpio/gpiolib.h

···
 	struct module		*owner;
 	struct gpio_chip __rcu	*chip;
 	struct gpio_desc	*descs;
-	int			base;
+	unsigned int		base;
 	u16			ngpio;
 	bool			can_sleep;
 	const char		*label;

include/linux/gpio.h

···
  * Until they are all fixed, leave 0-512 space for them.
  */
 #define GPIO_DYNAMIC_BASE	512
+/*
+ * Define the maximum of the possible GPIO in the global numberspace.
+ * While the GPIO base and numbers are positive, we limit it with signed
+ * maximum as a lot of code is using negative values for special cases.
+ */
+#define GPIO_DYNAMIC_MAX	INT_MAX
 
 /* Always use the library code for GPIO management calls,
  * or when sleeping may be involved.