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-rw-r--r--Documentation/gpio.txt10
1 files changed, 10 insertions, 0 deletions
diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt
index 9633da01ff4..792faa3c06c 100644
--- a/Documentation/gpio.txt
+++ b/Documentation/gpio.txt
@@ -617,6 +617,16 @@ and have the following read/write attributes:
is configured as an output, this value may be written;
any nonzero value is treated as high.
+ If the pin can be configured as interrupt-generating interrupt
+ and if it has been configured to generate interrupts (see the
+ description of "edge"), you can poll(2) on that file and
+ poll(2) will return whenever the interrupt was triggered. If
+ you use poll(2), set the events POLLPRI and POLLERR. If you
+ use select(2), set the file descriptor in exceptfds. After
+ poll(2) returns, either lseek(2) to the beginning of the sysfs
+ file and read the new value or close the file and re-open it
+ to read the value.
+
"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.