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-rw-r--r--Documentation/i2c/smbus-protocol16
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diff --git a/Documentation/i2c/smbus-protocol b/Documentation/i2c/smbus-protocol
index 9df47441f0e7..7c19d1a2bea0 100644
--- a/Documentation/i2c/smbus-protocol
+++ b/Documentation/i2c/smbus-protocol
@@ -185,6 +185,22 @@ the protocol. All ARP communications use slave address 0x61 and
require PEC checksums.
+SMBus Alert
+===========
+
+SMBus Alert was introduced in Revision 1.0 of the specification.
+
+The SMBus alert protocol allows several SMBus slave devices to share a
+single interrupt pin on the SMBus master, while still allowing the master
+to know which slave triggered the interrupt.
+
+This is implemented the following way in the Linux kernel:
+* I2C bus drivers which support SMBus alert should call
+ i2c_setup_smbus_alert() to setup SMBus alert support.
+* I2C drivers for devices which can trigger SMBus alerts should implement
+ the optional alert() callback.
+
+
I2C Block Transactions
======================