This patch adds driver support for the eQEP (enhanced Quadrature Encoder Pulse) module within each of the PWMSS units in the AM335x. The eQEP module is used for hardware decoding of rotrary encoders, motor encoders etc.
Because the PWMSS module includes several components some of the existing code in the pwm driver could be reused. To make this common I have added a pwmss.h header and moved some of the pwmss specific defines and enum to this file. The pwmss.c file contains a refactored (simplified) version of the clock configuration method that was previously in the pwm.c file. The pwmss_module_clk_config will now be shared by both the pwm and eqep drivers (and eventually the ecap driver if that is ever added). The approach taken with the qep.h header was to move some of the qep specific defines from the am335x.h header to this file. They are specific to the qep function and would likely never be referenced by anything other than this driver. Doing this keeps these definitions with the driver code and reduces clutter in am335x.h header. The driver supports two primary modes of operation. A polled mode (which is the default mode), and an interrupt event driven mode. The one area of the patch that I am least happy with and could do with some advice on is the callback approach I have used for the interrupt event driven model. Here a unit timer is configured with a set time period (in nanoseconds) and on expiry the unit timer raises an interrupt. The interrupt handler calls an optional callback function that the user can supply when setting the unit timer period via the beagle_eqep_set_timer_period. Although this works ok, I realise that calling a user function from a OS level interrupt is not desirable. Better suggestions for this would be gratefully received. I will send a follow up email including some sample test programs with their associated output. Regards, James James Fitzsimons (1): Adding QEP driver to Beaglebone bsp bsps/arm/beagle/headers.am | 2 + bsps/arm/beagle/include/bsp/bbb-pwm.h | 11 - bsps/arm/beagle/include/bsp/pwmss.h | 54 +++ bsps/arm/beagle/include/bsp/qep.h | 331 ++++++++++++++++++ bsps/arm/beagle/pwm/pwm.c | 64 +--- bsps/arm/beagle/pwmss/pwmss.c | 64 ++++ bsps/arm/beagle/qep/qep.c | 435 ++++++++++++++++++++++++ c/src/lib/libbsp/arm/beagle/Makefile.am | 6 + 8 files changed, 896 insertions(+), 71 deletions(-) create mode 100644 bsps/arm/beagle/include/bsp/pwmss.h create mode 100644 bsps/arm/beagle/include/bsp/qep.h create mode 100644 bsps/arm/beagle/pwmss/pwmss.c create mode 100644 bsps/arm/beagle/qep/qep.c -- 2.17.1 _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
