On Thu, Sep 08, 2011 at 06:57:04PM +0530, AnilKumar, Chimata wrote: > Hi All, > > I am developing a driver for TI's enhanced Quadrature Encoder Pulse > (eQEP) module. Details of the module at > http://www.ti.com/lit/ug/sprufu8/sprufu8.pdf > > Little description about the module:- > > This module is used for direct interface with a linear or rotary > incremental encoder. > > Main features of the module: > a. Provides the direction of the motor (clock or anti-clock) > b. Provides position count values, which can be used to compute speed > of a machine (motor/generator) > c. Generate a sync output from position compare sub-module > d. Can be used for High & Low speed measurements > > This module has 4 inputs from external rotary/linear encoder. > a. Input A (Input from external rotary encoder, a pulse train) > b. Input B (Input from external rotary encoder, a pulse train) > c. Index Event (Input from external rotary encoder, a index event. > This can be used as output, which can be generated after > position compare) > d. Strobe Event (Input from external rotary encoder, a strobe event. > This can be used as output, which can be generated after > position compare) > > The module provides pre-analyzed data based on the above four input > signals. We can use the data directly for knowing the position and > direction details. > > I have few questions related to this:- > > 1. What subsystem this driver fit into? Input subsystem or UIO > subsystem? > > Why I think it may fit into UIO subsystem? > a. Same driver is used for lot of applications like motor control, > volume control and menu navigation. This means we have to provide > lot of flexibility to the user in configuring the hardware to work > for different applications. Does it use the UIO interface to userspace? If not, then it's not a UIO driver. > Why I think it may fit into Input subsystem? > a. The module is receiving the signals from external encoder. Based > on the signals it will generate some events, which we have to handle > at the user space. > b. I found some encoder drivers are already present under input > subsystem (example drivers/input/misc/rotary-encoder.c) > > But, the current rotary encoder drivers are developed for much simpler > hardware. > > It looks like we need some additional interfaces to cater to the > hardware capabilities. I am thinking of sysfs interfaces which > allow user to directly configure the hardware for position control, > position compare, input source selection, capture timer period, > speed and direction of rotation. That sounds like you want the IIO interface in drivers/staging/iio/ right? That api handles all sorts of stuff like this. greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
