1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/fs.h> 3 #include <linux/init.h> 4 #include <linux/proc_fs.h> 5 #include <linux/seq_file.h> 6 7 static int devinfo_show(struct seq_file *f, void *v) 8 { 9 int i = *(loff_t *) v; 10 11 if (i < CHRDEV_MAJOR_MAX) { 12 if (i == 0) 13 seq_puts(f, "Character devices:\n"); 14 chrdev_show(f, i); 15 } 16 #ifdef CONFIG_BLOCK 17 else { 18 i -= CHRDEV_MAJOR_MAX; 19 if (i == 0) 20 seq_puts(f, "\nBlock devices:\n"); 21 blkdev_show(f, i); 22 } 23 #endif 24 return 0; 25 } 26 27 static void *devinfo_start(struct seq_file *f, loff_t *pos) 28 { 29 if (*pos < (BLKDEV_MAJOR_MAX + CHRDEV_MAJOR_MAX)) 30 return pos; 31 return NULL; 32 } 33 34 static void *devinfo_next(struct seq_file *f, void *v, loff_t *pos) 35 { 36 (*pos)++; 37 if (*pos >= (BLKDEV_MAJOR_MAX + CHRDEV_MAJOR_MAX)) 38 return NULL; 39 return pos; 40 } 41 42 static void devinfo_stop(struct seq_file *f, void *v) 43 { 44 /* Nothing to do */ 45 } 46 47 static const struct seq_operations devinfo_ops = { 48 .start = devinfo_start, 49 .next = devinfo_next, 50 .stop = devinfo_stop, 51 .show = devinfo_show 52 }; 53 54 static int __init proc_devices_init(void) 55 { 56 proc_create_seq("devices", 0, NULL, &devinfo_ops); 57 return 0; 58 } 59 fs_initcall(proc_devices_init); 60