Merge tag 'gpio-v3.13-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio

Pull GPIO fixes from Linus Walleij:
 "Here are a few more GPIO patches, we're a bit noisy for being the GPIO
  subsystem, mostly due to the new descriptor API, but all is getting
  into shape.

   - Fix compile warnings

   - Fix overly talkative diagnostic messages from usual use cases wrt
     GPIO descriptors

   - Add a documentation 00-INDEX

   - Use platform GPIOs as fallback when ACPI or device tree is used as
     the primary means to get GPIO lines

   - A bug fix for the MPC8572/MPC8536 fixing erroneous input data"

* tag 'gpio-v3.13-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio:
  gpiolib: change a warning to debug message when failing to get gpio
  powerpc/gpio: Fix the wrong GPIO input data on MPC8572/MPC8536
  gpiolib: use platform GPIO mappings as fallback
  Documentation: gpiolib: add 00-INDEX file
  gpiolib: fix lookup of platform-mapped GPIOs
  gpiolib: add missing declarations

Documentation/gpio/00-INDEX

@@ -0,0 +1,14 @@
+00-INDEX
+	- This file
+gpio.txt
+	- Introduction to GPIOs and their kernel interfaces
+consumer.txt
+	- How to obtain and use GPIOs in a driver
+driver.txt
+	- How to write a GPIO driver
+board.txt
+	- How to assign GPIOs to a consumer device and a function
+sysfs.txt
+	- Information about the GPIO sysfs interface
+gpio-legacy.txt
+	- Historical documentation of the deprecated GPIO integer interface

drivers/gpio/gpio-mpc8xxx.c

@@ -70,10 +70,14 @@ static int mpc8572_gpio_get(struct gpio_chip *gc, unsigned int gpio)
 	u32 val;
 	struct of_mm_gpio_chip *mm = to_of_mm_gpio_chip(gc);
 	struct mpc8xxx_gpio_chip *mpc8xxx_gc = to_mpc8xxx_gpio_chip(mm);
+	u32 out_mask, out_shadow;
 
-	val = in_be32(mm->regs + GPIO_DAT) & ~in_be32(mm->regs + GPIO_DIR);
+	out_mask = in_be32(mm->regs + GPIO_DIR);
 
-	return (val | mpc8xxx_gc->data) & mpc8xxx_gpio2mask(gpio);
+	val = in_be32(mm->regs + GPIO_DAT) & ~out_mask;
+	out_shadow = mpc8xxx_gc->data & out_mask;
+
+	return (val | out_shadow) & mpc8xxx_gpio2mask(gpio);
 }
 
 static int mpc8xxx_gpio_get(struct gpio_chip *gc, unsigned int gpio)

drivers/gpio/gpiolib.c

@@ -2368,7 +2368,7 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
 				continue;
 			}
 
-			if (chip->ngpio >= p->chip_hwnum) {
+			if (chip->ngpio <= p->chip_hwnum) {
 				dev_warn(dev, "GPIO chip %s has %d GPIOs\n",
 					 chip->label, chip->ngpio);
 				continue;
@@ -2418,7 +2418,7 @@ struct gpio_desc *__must_check gpiod_get_index(struct device *dev,
 					       const char *con_id,
 					       unsigned int idx)
 {
-	struct gpio_desc *desc;
+	struct gpio_desc *desc = NULL;
 	int status;
 	enum gpio_lookup_flags flags = 0;
 
@@ -2431,13 +2431,23 @@ struct gpio_desc *__must_check gpiod_get_index(struct device *dev,
 	} else if (IS_ENABLED(CONFIG_ACPI) && dev && ACPI_HANDLE(dev)) {
 		dev_dbg(dev, "using ACPI for GPIO lookup\n");
 		desc = acpi_find_gpio(dev, con_id, idx, &flags);
-	} else {
+	}
+
+	/*
+	 * Either we are not using DT or ACPI, or their lookup did not return
+	 * a result. In that case, use platform lookup as a fallback.
+	 */
+	if (!desc || IS_ERR(desc)) {
+		struct gpio_desc *pdesc;
 		dev_dbg(dev, "using lookup tables for GPIO lookup");
-		desc = gpiod_find(dev, con_id, idx, &flags);
+		pdesc = gpiod_find(dev, con_id, idx, &flags);
+		/* If used as fallback, do not replace the previous error */
+		if (!IS_ERR(pdesc) || !desc)
+			desc = pdesc;
 	}
 
 	if (IS_ERR(desc)) {
-		dev_warn(dev, "lookup for GPIO %s failed\n", con_id);
+		dev_dbg(dev, "lookup for GPIO %s failed\n", con_id);
 		return desc;
 	}
 

include/linux/gpio/driver.h

@@ -2,9 +2,12 @@
 #define __LINUX_GPIO_DRIVER_H
 
 #include <linux/types.h>
+#include <linux/module.h>
 
 struct device;
 struct gpio_desc;
+struct of_phandle_args;
+struct device_node;
 struct seq_file;
 
 /**