1*4882a593SmuzhiyunWhat: /sys/class/gpio/ 2*4882a593SmuzhiyunDate: July 2008 3*4882a593SmuzhiyunKernelVersion: 2.6.27 4*4882a593SmuzhiyunContact: Linus Walleij <linusw@kernel.org> 5*4882a593SmuzhiyunDescription: 6*4882a593Smuzhiyun 7*4882a593Smuzhiyun As a Kconfig option, individual GPIO signals may be accessed from 8*4882a593Smuzhiyun userspace. GPIOs are only made available to userspace by an explicit 9*4882a593Smuzhiyun "export" operation. If a given GPIO is not claimed for use by 10*4882a593Smuzhiyun kernel code, it may be exported by userspace (and unexported later). 11*4882a593Smuzhiyun Kernel code may export it for complete or partial access. 12*4882a593Smuzhiyun 13*4882a593Smuzhiyun GPIOs are identified as they are inside the kernel, using integers in 14*4882a593Smuzhiyun the range 0..INT_MAX. See Documentation/admin-guide/gpio for more information. 15*4882a593Smuzhiyun 16*4882a593Smuzhiyun :: 17*4882a593Smuzhiyun 18*4882a593Smuzhiyun /sys/class/gpio 19*4882a593Smuzhiyun /export ... asks the kernel to export a GPIO to userspace 20*4882a593Smuzhiyun /unexport ... to return a GPIO to the kernel 21*4882a593Smuzhiyun /gpioN ... for each exported GPIO #N OR 22*4882a593Smuzhiyun /<LINE-NAME> ... for a properly named GPIO line 23*4882a593Smuzhiyun /value ... always readable, writes fail for input GPIOs 24*4882a593Smuzhiyun /direction ... r/w as: in, out (default low); write: high, low 25*4882a593Smuzhiyun /edge ... r/w as: none, falling, rising, both 26*4882a593Smuzhiyun /gpiochipN ... for each gpiochip; #N is its first GPIO 27*4882a593Smuzhiyun /base ... (r/o) same as N 28*4882a593Smuzhiyun /label ... (r/o) descriptive, not necessarily unique 29*4882a593Smuzhiyun /ngpio ... (r/o) number of GPIOs; numbered N to N + (ngpio - 1) 30*4882a593Smuzhiyun 31*4882a593Smuzhiyun This ABI is deprecated and will be removed after 2020. It is 32*4882a593Smuzhiyun replaced with the GPIO character device. 33