/* * linux/drivers/char/misc.c * * Generic misc open routine by Johan Myreen * * Based on code from Linus * * Teemu Rantanen's Microsoft Busmouse support and Derrick Cole's * changes incorporated into 0.97pl4 * by Peter Cervasio (pete%q106fm.uucp@wupost.wustl.edu) (08SEP92) * See busmouse.c for particulars. * * Made things a lot mode modular - easy to compile in just one or two * of the misc drivers, as they are now completely independent. Linus. * * Support for loadable modules. 8-Sep-95 Philip Blundell * * Fixed a failing symbol register to free the device registration * Alan Cox 21-Jan-96 * * Dynamic minors and /proc/mice by Alessandro Rubini. 26-Mar-96 * * Renamed to misc and miscdevice to be more accurate. Alan Cox 26-Mar-96 * * Handling of mouse minor numbers for kerneld: * Idea by Jacques Gelinas , * adapted by Bjorn Ekwall * corrected by Alan Cox * * Changes for kmod (from kerneld): * Cyrus Durgin * * Added devfs support. Richard Gooch 10-Jan-1998 */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "busmouse.h" /* * Head entry for the doubly linked miscdevice list */ static struct miscdevice misc_list = { 0, "head", NULL, &misc_list, &misc_list }; static DECLARE_MUTEX(misc_sem); /* * Assigned numbers, used for dynamic minors */ #define DYNAMIC_MINORS 64 /* like dynamic majors */ static unsigned char misc_minors[DYNAMIC_MINORS / 8]; extern int psaux_init(void); #ifdef CONFIG_SGI_NEWPORT_GFX extern void gfx_register(void); #endif extern void streamable_init(void); extern int rtc_DP8570A_init(void); extern int rtc_MK48T08_init(void); extern int ds1286_init(void); extern int pmu_device_init(void); extern int tosh_init(void); extern int i8k_init(void); static int misc_read_proc(char *buf, char **start, off_t offset, int len, int *eof, void *private) { struct miscdevice *p; int written; written=0; for (p = misc_list.next; p != &misc_list && written < len; p = p->next) { written += sprintf(buf+written, "%3i %s\n",p->minor, p->name ?: ""); if (written < offset) { offset -= written; written = 0; } } *start = buf + offset; written -= offset; if(written > len) { *eof = 0; return len; } *eof = 1; return (written<0) ? 0 : written; } static int misc_open(struct inode * inode, struct file * file) { int minor = MINOR(inode->i_rdev); struct miscdevice *c; int err = -ENODEV; struct file_operations *old_fops, *new_fops = NULL; down(&misc_sem); c = misc_list.next; while ((c != &misc_list) && (c->minor != minor)) c = c->next; if (c != &misc_list) new_fops = fops_get(c->fops); if (!new_fops) { char modname[20]; up(&misc_sem); sprintf(modname, "char-major-%d-%d", MISC_MAJOR, minor); request_module(modname); down(&misc_sem); c = misc_list.next; while ((c != &misc_list) && (c->minor != minor)) c = c->next; if (c == &misc_list || (new_fops = fops_get(c->fops)) == NULL) goto fail; } err = 0; old_fops = file->f_op; file->f_op = new_fops; if (file->f_op->open) { err=file->f_op->open(inode,file); if (err) { fops_put(file->f_op); file->f_op = fops_get(old_fops); } } fops_put(old_fops); fail: up(&misc_sem); return err; } static struct file_operations misc_fops = { owner: THIS_MODULE, open: misc_open, }; /** * misc_register - register a miscellaneous device * @misc: device structure * * Register a miscellaneous device with the kernel. If the minor * number is set to %MISC_DYNAMIC_MINOR a minor number is assigned * and placed in the minor field of the structure. For other cases * the minor number requested is used. * * The structure passed is linked into the kernel and may not be * destroyed until it has been unregistered. * * A zero is returned on success and a negative errno code for * failure. */ int misc_register(struct miscdevice * misc) { static devfs_handle_t devfs_handle; struct miscdevice *c; if (misc->next || misc->prev) return -EBUSY; down(&misc_sem); c = misc_list.next; while ((c != &misc_list) && (c->minor != misc->minor)) c = c->next; if (c != &misc_list) { up(&misc_sem); return -EBUSY; } if (misc->minor == MISC_DYNAMIC_MINOR) { int i = DYNAMIC_MINORS; while (--i >= 0) if ( (misc_minors[i>>3] & (1 << (i&7))) == 0) break; if (i<0) { up(&misc_sem); return -EBUSY; } misc->minor = i; } if (misc->minor < DYNAMIC_MINORS) misc_minors[misc->minor >> 3] |= 1 << (misc->minor & 7); if (!devfs_handle) devfs_handle = devfs_mk_dir (NULL, "misc", NULL); misc->devfs_handle = devfs_register (devfs_handle, misc->name, DEVFS_FL_NONE, MISC_MAJOR, misc->minor, S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP, misc->fops, NULL); /* * Add it to the front, so that later devices can "override" * earlier defaults */ misc->prev = &misc_list; misc->next = misc_list.next; misc->prev->next = misc; misc->next->prev = misc; up(&misc_sem); return 0; } /** * misc_deregister - unregister a miscellaneous device * @misc: device to unregister * * Unregister a miscellaneous device that was previously * successfully registered with misc_register(). Success * is indicated by a zero return, a negative errno code * indicates an error. */ int misc_deregister(struct miscdevice * misc) { int i = misc->minor; if (!misc->next || !misc->prev) return -EINVAL; down(&misc_sem); misc->prev->next = misc->next; misc->next->prev = misc->prev; misc->next = NULL; misc->prev = NULL; devfs_unregister (misc->devfs_handle); if (i < DYNAMIC_MINORS && i>0) { misc_minors[i>>3] &= ~(1 << (misc->minor & 7)); } up(&misc_sem); return 0; } EXPORT_SYMBOL(misc_register); EXPORT_SYMBOL(misc_deregister); int __init misc_init(void) { create_proc_read_entry("misc", 0, 0, misc_read_proc, NULL); #ifdef CONFIG_MVME16x rtc_MK48T08_init(); #endif #ifdef CONFIG_BVME6000 rtc_DP8570A_init(); #endif #ifdef CONFIG_SGI_DS1286 ds1286_init(); #endif #ifdef CONFIG_PMAC_PBOOK pmu_device_init(); #endif #ifdef CONFIG_SGI_NEWPORT_GFX gfx_register (); #endif #ifdef CONFIG_SGI_IP22 streamable_init (); #endif #ifdef CONFIG_SGI_NEWPORT_GFX gfx_register (); #endif #ifdef CONFIG_TOSHIBA tosh_init(); #endif #ifdef CONFIG_I8K i8k_init(); #endif if (devfs_register_chrdev(MISC_MAJOR,"misc",&misc_fops)) { printk("unable to get major %d for misc devices\n", MISC_MAJOR); return -EIO; } return 0; }