X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=Documentation%2Fhwmon%2Fltc4245;h=b478b08649658693697d3c6f8ee582c5524a8073;hb=e8cdfb0509f48d44d95d68d4f42d8d71a9ba4acd;hp=86b5880d8502b123e508c94330e61ea255db1292;hpb=60eab877a9581b479c6c7d7913ce8070a0ace960;p=firefly-linux-kernel-4.4.55.git

diff --git a/Documentation/hwmon/ltc4245 b/Documentation/hwmon/ltc4245
index 86b5880d8502..b478b0864965 100644
--- a/Documentation/hwmon/ltc4245
+++ b/Documentation/hwmon/ltc4245
@@ -72,9 +72,31 @@ in6_min_alarm		5v  output undervoltage alarm
 in7_min_alarm		3v  output undervoltage alarm
 in8_min_alarm		Vee (-12v) output undervoltage alarm
 
-in9_input		GPIO voltage data
+in9_input		GPIO voltage data (see note 1)
+in10_input		GPIO voltage data (see note 1)
+in11_input		GPIO voltage data (see note 1)
 
 power1_input		12v power usage (mW)
 power2_input		5v  power usage (mW)
 power3_input		3v  power usage (mW)
 power4_input		Vee (-12v) power usage (mW)
+
+
+Note 1
+------
+
+If you have NOT configured the driver to sample all GPIO pins as analog
+voltages, then the in10_input and in11_input sysfs attributes will not be
+created. The driver will sample the GPIO pin that is currently connected to the
+ADC as an analog voltage, and report the value in in9_input.
+
+If you have configured the driver to sample all GPIO pins as analog voltages,
+then they will be sampled in round-robin fashion. If userspace reads too
+slowly, -EAGAIN will be returned when you read the sysfs attribute containing
+the sensor reading.
+
+The LTC4245 chip can be configured to sample all GPIO pins with two methods:
+1) platform data -- see include/linux/i2c/ltc4245.h
+2) OF device tree -- add the "ltc4245,use-extra-gpios" property to each chip
+
+The default mode of operation is to sample a single GPIO pin.