X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=Documentation%2Fgpio.txt;h=fa4dc077ae0eed46adf4a7312f5d033fec717fdf;hb=f52d7a4393136107f526040f6ef190ab49032496;hp=e4b6985044a263249976cc0ca985529555007462;hpb=19f594600110377ec4037fdf7fb93a25ec516212;p=safe%2Fjmp%2Flinux-2.6

diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt
index e4b6985..fa4dc07 100644
--- a/Documentation/gpio.txt
+++ b/Documentation/gpio.txt
@@ -524,6 +524,13 @@ and have the following read/write attributes:
 		is configured as an output, this value may be written;
 		any nonzero value is treated as high.
 
+	"edge" ... reads as either "none", "rising", "falling", or
+		"both". Write these strings to select the signal edge(s)
+		that will make poll(2) on the "value" file return.
+
+		This file exists only if the pin can be configured as an
+		interrupt generating input pin.
+
 GPIO controllers have paths like /sys/class/gpio/chipchip42/ (for the
 controller implementing GPIOs starting at #42) and have the following
 read-only attributes:
@@ -555,6 +562,11 @@ requested using gpio_request():
 	/* reverse gpio_export() */
 	void gpio_unexport();
 
+	/* create a sysfs link to an exported GPIO node */
+	int gpio_export_link(struct device *dev, const char *name,
+		unsigned gpio)
+
+
 After a kernel driver requests a GPIO, it may only be made available in
 the sysfs interface by gpio_export().  The driver can control whether the
 signal direction may change.  This helps drivers prevent userspace code
@@ -563,3 +575,8 @@ from accidentally clobbering important system state.
 This explicit exporting can help with debugging (by making some kinds
 of experiments easier), or can provide an always-there interface that's
 suitable for documenting as part of a board support package.
+
+After the GPIO has been exported, gpio_export_link() allows creating
+symlinks from elsewhere in sysfs to the GPIO sysfs node.  Drivers can
+use this to provide the interface under their own device in sysfs with
+a descriptive name.