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

4 files changed, 38 insertions, 7 deletions

diff --git a/Documentation/gpio/00-INDEX b/Documentation/gpio/00-INDEX
new file mode 100644
index 000000000000..1de43ae46ae6
--- /dev/null
+++ b/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
diff --git a/drivers/gpio/gpio-mpc8xxx.c b/drivers/gpio/gpio-mpc8xxx.c
index 914e859e3eda..d7d6d72eba33 100644
--- a/drivers/gpio/gpio-mpc8xxx.c
+++ b/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)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index ac53a9593662..85f772c0b26a 100644
--- a/drivers/gpio/gpiolib.c
+++ b/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;
         }
 
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index 82eac610ce1a..3ea2cf6b0e6c 100644
--- a/include/linux/gpio/driver.h
+++ b/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;
 
 /**