The reference driver polled but mentioned it was possible to sleep
for a computed period to know when it's ready to read. However, polling
with minimal sleeps is quick and works. This also improves responsiveness
from the driver.
Testing: tested on ast2400 on quanta-q71l
Signed-off-by: Patrick Venture <venture@google.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reduce the fan_tach period such that the fan controller uses a shorter
period to measure the rpm.
The original period of 0x1000 was chosen as a conversative value from the
reference implementation. Through experimentation on the quanta-q71l
board, I was able to drive the number down which ultimately reduced the
time the controller would use to determine the fan_tach. This value was
recently tested and accepted downstream on the IBM Zaius board which uses
the ast2500.
Future work: It may be worthwhile as this is a tunable parameter to the
system, to allow overriding it through the device tree.
Testing: Tested on an ast2400 sitting on a quanta-q71l and ast2500 on
power9.
Signed-off-by: Patrick Venture <venture@google.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
The aspeed-pwm-tacho controller supports measuring the fan tach by using
leading, falling, or both edges. This change allows the driver to
support either of the three configurations and will appropriately modify
the returned tach data.
If the controller is measuring with both edges it can return a value more
quickly to the requestor. This version of the driver should still take ~1s
to return with an RPM value per fan, however, it can be tuned faster with
double edge counting enabled than without.
I tested this and found the number returned matched what I expected.
Signed-off-by: Patrick Venture <venture@google.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Make fan and pwm names in sysfs start with index 1 in accordance to
Documentation/hwmon/sysfs-interface conventions.
Current implementation starts with index 0, making tools such as
sensors(1) skip the first fan.
Signed-off-by: Stefan Schaeckeler <sschaeck@cisco.com>
Fixes: 2d7a548a3e ("drivers: hwmon: Support for ASPEED PWM/Fan tach")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Call of_node_put() on a node claimed with of_node_get() or by any other
means such as for_each_child_of_node().
Signed-off-by: Stefan Schaeckeler <sschaeck@cisco.com>
Fixes: 2d7a548a3e ("drivers: hwmon: Support for ASPEED PWM/Fan tach")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
When the controller fails to provide an RPM reading within the alloted
time; the driver returns -ETIMEDOUT and no file contents.
Signed-off-by: Patrick Venture <venture@google.com>
Fixes: 2d7a548a3e ("drivers: hwmon: Support for ASPEED PWM/Fan tach")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
The ASPEED AST2400/2500 PWM controller supports 8 PWM output ports.
The ASPEED AST2400/2500 Fan tach controller supports 16 tachometer
inputs.
The device driver matches on the device tree node. The configuration
values are read from the device tree and written to the respective
registers.
The driver provides a sysfs entries through which the user can
configure the duty-cycle value (ranging from 0 to 100 percent) and read
the fan tach rpm value.
Signed-off-by: Jaghathiswari Rankappagounder Natarajan <jaghu@google.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Patrick Venture