hwmon: Add tachometer pulses per fan revolution to sysfs ABI

Some fan control chips support a configuration register to set the number of
tachometer pulses per fan revolution. Add an ABI attribute to support this
configuration register.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Acked-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/Documentation/hwmon/sysfs-interface b/Documentation/hwmon/sysfs-interface
index c6559f153589..83a698773ade 100644
--- a/Documentation/hwmon/sysfs-interface
+++ b/Documentation/hwmon/sysfs-interface
@@ -187,6 +187,17 @@ fan[1-*]_div	Fan divisor.
                 Note that this is actually an internal clock divisor, which
                 affects the measurable speed range, not the read value.
 
+fan[1-*]_pulses Number of tachometer pulses per fan revolution.
+                Integer value, typically between 1 and 4.
+                RW
+                This value is a characteristic of the fan connected to the
+                device's input, so it has to be set in accordance with the fan
+                model.
+                Should only be created if the chip has a register to configure
+                the number of pulses. In the absence of such a register (and
+                thus attribute) the value assumed by all devices is 2 pulses
+                per fan revolution.
+
 fan[1-*]_target
                 Desired fan speed
                 Unit: revolution/min (RPM)