Pwm

PWM, Drivers Enablement

Enable all PWM needed drivers via menuconfig and compile your Kernel

user@Minnowboard:~$ cd linux
user@Minnowboard:~$ make menuconfig

@Linux Kernel Menuconfig > Device Drivers
Symbol: PWM [=y]
Prompt: Generic Pulse-Width Modulation (PWM) support

@Linux Kernel Menuconfig > Device Drivers > Pulse-Width Modulation (PWM) Support
Symbol: PWM_LPSS [=m]
Prompt: Intel LPSS PWM support

@Linux Kernel Menuconfig > Device Drivers > Pulse-Width Modulation (PWM) Support
Symbol: PWM_LPSS_PCI [=m]
Prompt: Intel LPSS PWM PCI driver

@Linux Kernel Menuconfig > Device Drivers > Pulse-Width Modulation (PWM) Support
Symbol: PWM_LPSS_PLATFORM [=m]
Prompt: Intel LPSS PWM platform driver

CC      drivers/pwm/core.o
CC      drivers/pwm/sysfs.o
LD      drivers/pwm/built-in.o
CC [M]  drivers/pwm/pwm-lpss.o
CC [M]  drivers/pwm/pwm-lpss-pci.o
CC [M]  drivers/pwm/pwm-lpss-platform.o
LD      drivers/built-in.o

Building modules, stage 2.
MODPOST 3027 modules
CC      drivers/pwm/pwm-lpss-pci.mod.o
LD [M]  drivers/pwm/pwm-lpss-pci.ko
CC      drivers/pwm/pwm-lpss-platform.mod.o
LD [M]  drivers/pwm/pwm-lpss-platform.ko
CC      drivers/pwm/pwm-lpss.mod.o
LD [M]  drivers/pwm/pwm-lpss.ko

PWM, UserSpace Usage, SysFs

root@minnowboard:# ls /sys/class/pwm/
pwmchip0  pwmchip1
root@minnowboard:# ls /sys/class/pwm/pwmchip0
device    export    npwm  power  subsystem    uevent    unexport
root@minnowboard:# echo 0 > /sys/class/pwm/pwmchip0/export
root@minnowboard:# ls /sys/class/pwm/pwmchip0
device    export    npwm  power  pwm0  subsystem  uevent  unexport
root@minnowboard:# ls /sys/class/pwm/pwmchip0/pwm0/
duty_cycle  enable  period  polarity  power  uevent
root@minnowboard:# cat /sys/class/pwm/pwmchip0/pwm0/enable
root@minnowboard:# echo 1 > /sys/class/pwm/pwmchip0/pwm0/enable
root@minnowboard:# echo 100 > /sys/class/pwm/pwmchip0/pwm0/period
root@minnowboard:# echo 50 > /sys/class/pwm/pwmchip0/pwm0/duty_cycle
root@minnowboard:# cat /sys/class/pwm/pwmchip0/pwm0/enable
root@minnowboard:# cat /sys/class/pwm/pwmchip0/pwm0/period
root@minnowboard:# cat /sys/class/pwm/pwmchip0/pwm0/duty_cycle