usr_buf 200 drivers/gpio/gpio-mockup.c char __user *usr_buf, usr_buf 221 drivers/gpio/gpio-mockup.c return simple_read_from_buffer(usr_buf, size, ppos, buf, cnt); usr_buf 225 drivers/gpio/gpio-mockup.c const char __user *usr_buf, usr_buf 239 drivers/gpio/gpio-mockup.c rv = kstrtoint_from_user(usr_buf, size, 0, &val);