// SPDX-License-Identifier: GPL-2.0 #include <linux/fs.h> #include <linux/init.h> #include <linux/proc_fs.h> #include <linux/seq_file.h> static int devinfo_show(struct seq_file *f, void *v) { int i = *(loff_t *) v; if (i < CHRDEV_MAJOR_MAX) { if (i == 0) seq_puts(f, "Character devices:\n"); chrdev_show(f, i); } #ifdef CONFIG_BLOCK else { i -= CHRDEV_MAJOR_MAX; if (i == 0) seq_puts(f, "\nBlock devices:\n"); blkdev_show(f, i); } #endif return 0; } static void *devinfo_start(struct seq_file *f, loff_t *pos) { if (*pos < (BLKDEV_MAJOR_MAX + CHRDEV_MAJOR_MAX)) return pos; return NULL; } static void *devinfo_next(struct seq_file *f, void *v, loff_t *pos) { (*pos)++; if (*pos >= (BLKDEV_MAJOR_MAX + CHRDEV_MAJOR_MAX)) return NULL; return pos; } static void devinfo_stop(struct seq_file *f, void *v) { /* Nothing to do */ } static const struct seq_operations devinfo_ops = { .start = devinfo_start, .next = devinfo_next, .stop = devinfo_stop, .show = devinfo_show }; static int __init proc_devices_init(void) { proc_create_seq("devices", 0, NULL, &devinfo_ops); return 0; } fs_initcall(proc_devices_init);