of/gpio: Implement of_get_gpio_flags()

This adds a new function, of_get_gpio_flags, which is like
of_get_gpio(), but accepts a new "flags" argument.  This new function
will be used by the drivers that need to retrieve additional GPIO
information, such as active-low flag.

Also, this changes the default ("simple") .xlate routine to warn about
bogus (< 2) #gpio-cells usage: the second cell should always be present
for GPIO flags.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 29 insertions, 7 deletions

diff --git a/drivers/of/gpio.c b/drivers/of/gpio.c
index 7cd7301b5839..a4ba217116eb 100644
--- a/drivers/of/gpio.c
+++ b/drivers/of/gpio.c
@@ -19,14 +19,17 @@
 #include <asm/prom.h>
 
 /**
- * of_get_gpio - Get a GPIO number from the device tree to use with GPIO API
+ * of_get_gpio_flags - Get a GPIO number and flags to use with GPIO API
  * @np:         device node to get GPIO from
  * @index:      index of the GPIO
+ * @flags:      a flags pointer to fill in
  *
  * Returns GPIO number to use with Linux generic GPIO API, or one of the errno
- * value on the error condition.
+ * value on the error condition. If @flags is not NULL the function also fills
+ * in flags for the GPIO.
  */
-int of_get_gpio(struct device_node *np, int index)
+int of_get_gpio_flags(struct device_node *np, int index,
+                      enum of_gpio_flags *flags)
 {
         int ret;
         struct device_node *gc;
@@ -59,7 +62,11 @@ int of_get_gpio(struct device_node *np, int index)
                 goto err1;
         }
 
-        ret = of_gc->xlate(of_gc, np, gpio_spec);
+        /* .xlate might decide to not fill in the flags, so clear it. */
+        if (flags)
+                *flags = 0;
+
+        ret = of_gc->xlate(of_gc, np, gpio_spec, flags);
         if (ret < 0)
                 goto err1;
 
@@ -70,26 +77,41 @@ err0:
         pr_debug("%s exited with status %d\n", __func__, ret);
         return ret;
 }
-EXPORT_SYMBOL(of_get_gpio);
+EXPORT_SYMBOL(of_get_gpio_flags);
 
 /**
- * of_gpio_simple_xlate - translate gpio_spec to the GPIO number
+ * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
  * @of_gc:      pointer to the of_gpio_chip structure
  * @np:         device node of the GPIO chip
  * @gpio_spec:  gpio specifier as found in the device tree
+ * @flags:      a flags pointer to fill in
  *
  * This is simple translation function, suitable for the most 1:1 mapped
  * gpio chips. This function performs only one sanity check: whether gpio
  * is less than ngpios (that is specified in the gpio_chip).
  */
 int of_gpio_simple_xlate(struct of_gpio_chip *of_gc, struct device_node *np,
-                         const void *gpio_spec)
+                         const void *gpio_spec, enum of_gpio_flags *flags)
 {
         const u32 *gpio = gpio_spec;
 
+        /*
+         * We're discouraging gpio_cells < 2, since that way you'll have to
+         * write your own xlate function (that will have to retrive the GPIO
+         * number and the flags from a single gpio cell -- this is possible,
+         * but not recommended).
+         */
+        if (of_gc->gpio_cells < 2) {
+                WARN_ON(1);
+                return -EINVAL;
+        }
+
         if (*gpio > of_gc->gc.ngpio)
                 return -EINVAL;
 
+        if (flags)
+                *flags = gpio[1];
+
         return *gpio;
 }
 EXPORT_SYMBOL(of_gpio_simple_xlate);