fs/proc/devices.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 #include <linux/fs.h>
0003 #include <linux/init.h>
0004 #include <linux/proc_fs.h>
0005 #include <linux/seq_file.h>
0006 #include <linux/blkdev.h>
0007
0008 static int devinfo_show(struct seq_file *f, void *v)
0009 {
0010     int i = *(loff_t *) v;
0011
0012     if (i < CHRDEV_MAJOR_MAX) {
0013         if (i == 0)
0014             seq_puts(f, "Character devices:\n");
0015         chrdev_show(f, i);
0016     }
0017 #ifdef CONFIG_BLOCK
0018     else {
0019         i -= CHRDEV_MAJOR_MAX;
0020         if (i == 0)
0021             seq_puts(f, "\nBlock devices:\n");
0022         blkdev_show(f, i);
0023     }
0024 #endif
0025     return 0;
0026 }
0027
0028 static void *devinfo_start(struct seq_file *f, loff_t *pos)
0029 {
0030     if (*pos < (BLKDEV_MAJOR_MAX + CHRDEV_MAJOR_MAX))
0031         return pos;
0032     return NULL;
0033 }
0034
0035 static void *devinfo_next(struct seq_file *f, void *v, loff_t *pos)
0036 {
0037     (*pos)++;
0038     if (*pos >= (BLKDEV_MAJOR_MAX + CHRDEV_MAJOR_MAX))
0039         return NULL;
0040     return pos;
0041 }
0042
0043 static void devinfo_stop(struct seq_file *f, void *v)
0044 {
0045     /* Nothing to do */
0046 }
0047
0048 static const struct seq_operations devinfo_ops = {
0049     .start = devinfo_start,
0050     .next  = devinfo_next,
0051     .stop  = devinfo_stop,
0052     .show  = devinfo_show
0053 };
0054
0055 static int __init proc_devices_init(void)
0056 {
0057     proc_create_seq("devices", 0, NULL, &devinfo_ops);
0058     return 0;
0059 }
0060 fs_initcall(proc_devices_init);