601 lines
14 KiB
C
601 lines
14 KiB
C
/* -*- C -*-
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* main.c -- the bare scullc char module
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*
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* Copyright (C) 2001 Alessandro Rubini and Jonathan Corbet
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* Copyright (C) 2001 O'Reilly & Associates
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*
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* The source code in this file can be freely used, adapted,
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* and redistributed in source or binary form, so long as an
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* acknowledgment appears in derived source files. The citation
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* should list that the code comes from the book "Linux Device
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* Drivers" by Alessandro Rubini and Jonathan Corbet, published
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* by O'Reilly & Associates. No warranty is attached;
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* we cannot take responsibility for errors or fitness for use.
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*
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* $Id: _main.c.in,v 1.21 2004/10/14 20:11:39 corbet Exp $
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*/
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#include <linux/config.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/init.h>
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#include <linux/kernel.h> /* printk() */
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#include <linux/slab.h> /* kmalloc() */
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#include <linux/fs.h> /* everything... */
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#include <linux/errno.h> /* error codes */
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#include <linux/types.h> /* size_t */
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#include <linux/proc_fs.h>
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#include <linux/fcntl.h> /* O_ACCMODE */
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#include <linux/aio.h>
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#include <asm/uaccess.h>
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#include "scullc.h" /* local definitions */
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int scullc_major = SCULLC_MAJOR;
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int scullc_devs = SCULLC_DEVS; /* number of bare scullc devices */
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int scullc_qset = SCULLC_QSET;
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int scullc_quantum = SCULLC_QUANTUM;
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module_param(scullc_major, int, 0);
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module_param(scullc_devs, int, 0);
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module_param(scullc_qset, int, 0);
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module_param(scullc_quantum, int, 0);
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MODULE_AUTHOR("Alessandro Rubini");
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MODULE_LICENSE("Dual BSD/GPL");
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struct scullc_dev *scullc_devices; /* allocated in scullc_init */
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int scullc_trim(struct scullc_dev *dev);
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void scullc_cleanup(void);
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/* declare one cache pointer: use it for all devices */
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kmem_cache_t *scullc_cache;
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#ifdef SCULLC_USE_PROC /* don't waste space if unused */
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/*
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* The proc filesystem: function to read and entry
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*/
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void scullc_proc_offset(char *buf, char **start, off_t *offset, int *len)
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{
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if (*offset == 0)
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return;
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if (*offset >= *len) {
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/* Not there yet */
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*offset -= *len;
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*len = 0;
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} else {
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/* We're into the interesting stuff now */
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*start = buf + *offset;
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*offset = 0;
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}
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}
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/* FIXME: Do we need this here?? It be ugly */
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int scullc_read_procmem(char *buf, char **start, off_t offset,
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int count, int *eof, void *data)
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{
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int i, j, quantum, qset, len = 0;
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int limit = count - 80; /* Don't print more than this */
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struct scullc_dev *d;
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*start = buf;
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for(i = 0; i < scullc_devs; i++) {
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d = &scullc_devices[i];
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if (down_interruptible (&d->sem))
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return -ERESTARTSYS;
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qset = d->qset; /* retrieve the features of each device */
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quantum=d->quantum;
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len += sprintf(buf+len,"\nDevice %i: qset %i, quantum %i, sz %li\n",
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i, qset, quantum, (long)(d->size));
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for (; d; d = d->next) { /* scan the list */
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len += sprintf(buf+len," item at %p, qset at %p\n",d,d->data);
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scullc_proc_offset (buf, start, &offset, &len);
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if (len > limit)
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goto out;
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if (d->data && !d->next) /* dump only the last item - save space */
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for (j = 0; j < qset; j++) {
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if (d->data[j])
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len += sprintf(buf+len," % 4i:%8p\n",j,d->data[j]);
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scullc_proc_offset (buf, start, &offset, &len);
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if (len > limit)
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goto out;
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}
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}
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out:
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up (&scullc_devices[i].sem);
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if (len > limit)
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break;
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}
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*eof = 1;
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return len;
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}
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#endif /* SCULLC_USE_PROC */
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/*
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* Open and close
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*/
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int scullc_open (struct inode *inode, struct file *filp)
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{
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struct scullc_dev *dev; /* device information */
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/* Find the device */
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dev = container_of(inode->i_cdev, struct scullc_dev, cdev);
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/* now trim to 0 the length of the device if open was write-only */
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if ( (filp->f_flags & O_ACCMODE) == O_WRONLY) {
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if (down_interruptible (&dev->sem))
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return -ERESTARTSYS;
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scullc_trim(dev); /* ignore errors */
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up (&dev->sem);
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}
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/* and use filp->private_data to point to the device data */
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filp->private_data = dev;
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return 0; /* success */
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}
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int scullc_release (struct inode *inode, struct file *filp)
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{
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return 0;
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}
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/*
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* Follow the list
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*/
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struct scullc_dev *scullc_follow(struct scullc_dev *dev, int n)
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{
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while (n--) {
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if (!dev->next) {
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dev->next = kmalloc(sizeof(struct scullc_dev), GFP_KERNEL);
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memset(dev->next, 0, sizeof(struct scullc_dev));
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}
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dev = dev->next;
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continue;
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}
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return dev;
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}
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/*
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* Data management: read and write
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*/
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ssize_t scullc_read (struct file *filp, char __user *buf, size_t count,
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loff_t *f_pos)
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{
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struct scullc_dev *dev = filp->private_data; /* the first listitem */
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struct scullc_dev *dptr;
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int quantum = dev->quantum;
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int qset = dev->qset;
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int itemsize = quantum * qset; /* how many bytes in the listitem */
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int item, s_pos, q_pos, rest;
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ssize_t retval = 0;
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if (down_interruptible (&dev->sem))
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return -ERESTARTSYS;
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if (*f_pos > dev->size)
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goto nothing;
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if (*f_pos + count > dev->size)
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count = dev->size - *f_pos;
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/* find listitem, qset index, and offset in the quantum */
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item = ((long) *f_pos) / itemsize;
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rest = ((long) *f_pos) % itemsize;
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s_pos = rest / quantum; q_pos = rest % quantum;
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/* follow the list up to the right position (defined elsewhere) */
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dptr = scullc_follow(dev, item);
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if (!dptr->data)
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goto nothing; /* don't fill holes */
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if (!dptr->data[s_pos])
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goto nothing;
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if (count > quantum - q_pos)
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count = quantum - q_pos; /* read only up to the end of this quantum */
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if (copy_to_user (buf, dptr->data[s_pos]+q_pos, count)) {
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retval = -EFAULT;
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goto nothing;
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}
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up (&dev->sem);
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*f_pos += count;
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return count;
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nothing:
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up (&dev->sem);
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return retval;
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}
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ssize_t scullc_write (struct file *filp, const char __user *buf, size_t count,
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loff_t *f_pos)
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{
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struct scullc_dev *dev = filp->private_data;
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struct scullc_dev *dptr;
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int quantum = dev->quantum;
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int qset = dev->qset;
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int itemsize = quantum * qset;
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int item, s_pos, q_pos, rest;
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ssize_t retval = -ENOMEM; /* our most likely error */
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if (down_interruptible (&dev->sem))
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return -ERESTARTSYS;
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/* find listitem, qset index and offset in the quantum */
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item = ((long) *f_pos) / itemsize;
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rest = ((long) *f_pos) % itemsize;
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s_pos = rest / quantum; q_pos = rest % quantum;
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/* follow the list up to the right position */
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dptr = scullc_follow(dev, item);
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if (!dptr->data) {
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dptr->data = kmalloc(qset * sizeof(void *), GFP_KERNEL);
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if (!dptr->data)
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goto nomem;
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memset(dptr->data, 0, qset * sizeof(char *));
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}
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/* Allocate a quantum using the memory cache */
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if (!dptr->data[s_pos]) {
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dptr->data[s_pos] = kmem_cache_alloc(scullc_cache, GFP_KERNEL);
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if (!dptr->data[s_pos])
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goto nomem;
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memset(dptr->data[s_pos], 0, scullc_quantum);
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}
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if (count > quantum - q_pos)
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count = quantum - q_pos; /* write only up to the end of this quantum */
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if (copy_from_user (dptr->data[s_pos]+q_pos, buf, count)) {
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retval = -EFAULT;
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goto nomem;
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}
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*f_pos += count;
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/* update the size */
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if (dev->size < *f_pos)
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dev->size = *f_pos;
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up (&dev->sem);
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return count;
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nomem:
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up (&dev->sem);
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return retval;
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}
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/*
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* The ioctl() implementation
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*/
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int scullc_ioctl (struct inode *inode, struct file *filp,
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unsigned int cmd, unsigned long arg)
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{
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int err = 0, ret = 0, tmp;
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/* don't even decode wrong cmds: better returning ENOTTY than EFAULT */
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if (_IOC_TYPE(cmd) != SCULLC_IOC_MAGIC) return -ENOTTY;
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if (_IOC_NR(cmd) > SCULLC_IOC_MAXNR) return -ENOTTY;
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/*
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* the type is a bitmask, and VERIFY_WRITE catches R/W
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* transfers. Note that the type is user-oriented, while
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* verify_area is kernel-oriented, so the concept of "read" and
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* "write" is reversed
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*/
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if (_IOC_DIR(cmd) & _IOC_READ)
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err = !access_ok(VERIFY_WRITE, (void __user *)arg, _IOC_SIZE(cmd));
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else if (_IOC_DIR(cmd) & _IOC_WRITE)
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err = !access_ok(VERIFY_READ, (void __user *)arg, _IOC_SIZE(cmd));
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if (err)
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return -EFAULT;
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switch(cmd) {
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case SCULLC_IOCRESET:
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scullc_qset = SCULLC_QSET;
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scullc_quantum = SCULLC_QUANTUM;
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break;
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case SCULLC_IOCSQUANTUM: /* Set: arg points to the value */
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ret = __get_user(scullc_quantum, (int __user *) arg);
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break;
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case SCULLC_IOCTQUANTUM: /* Tell: arg is the value */
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scullc_quantum = arg;
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break;
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case SCULLC_IOCGQUANTUM: /* Get: arg is pointer to result */
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ret = __put_user (scullc_quantum, (int __user *) arg);
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break;
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case SCULLC_IOCQQUANTUM: /* Query: return it (it's positive) */
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return scullc_quantum;
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case SCULLC_IOCXQUANTUM: /* eXchange: use arg as pointer */
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tmp = scullc_quantum;
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ret = __get_user(scullc_quantum, (int __user *) arg);
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if (ret == 0)
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ret = __put_user(tmp, (int __user *) arg);
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break;
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case SCULLC_IOCHQUANTUM: /* sHift: like Tell + Query */
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tmp = scullc_quantum;
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scullc_quantum = arg;
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return tmp;
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case SCULLC_IOCSQSET:
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ret = __get_user(scullc_qset, (int __user *) arg);
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break;
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case SCULLC_IOCTQSET:
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scullc_qset = arg;
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break;
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case SCULLC_IOCGQSET:
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ret = __put_user(scullc_qset, (int __user *)arg);
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break;
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case SCULLC_IOCQQSET:
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return scullc_qset;
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case SCULLC_IOCXQSET:
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tmp = scullc_qset;
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ret = __get_user(scullc_qset, (int __user *)arg);
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if (ret == 0)
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ret = __put_user(tmp, (int __user *)arg);
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break;
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case SCULLC_IOCHQSET:
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tmp = scullc_qset;
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scullc_qset = arg;
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return tmp;
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default: /* redundant, as cmd was checked against MAXNR */
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return -ENOTTY;
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}
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return ret;
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}
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/*
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* The "extended" operations
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*/
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loff_t scullc_llseek (struct file *filp, loff_t off, int whence)
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{
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struct scullc_dev *dev = filp->private_data;
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long newpos;
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switch(whence) {
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case 0: /* SEEK_SET */
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newpos = off;
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break;
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case 1: /* SEEK_CUR */
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newpos = filp->f_pos + off;
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break;
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case 2: /* SEEK_END */
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newpos = dev->size + off;
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break;
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default: /* can't happen */
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return -EINVAL;
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}
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if (newpos<0) return -EINVAL;
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filp->f_pos = newpos;
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return newpos;
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}
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/*
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* A simple asynchronous I/O implementation.
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*/
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struct async_work {
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struct kiocb *iocb;
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int result;
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struct work_struct work;
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};
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/*
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* "Complete" an asynchronous operation.
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*/
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static void scullc_do_deferred_op(void *p)
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{
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struct async_work *stuff = (struct async_work *) p;
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aio_complete(stuff->iocb, stuff->result, 0);
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kfree(stuff);
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}
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static int scullc_defer_op(int write, struct kiocb *iocb, char __user *buf,
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size_t count, loff_t pos)
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{
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struct async_work *stuff;
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int result;
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/* Copy now while we can access the buffer */
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if (write)
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result = scullc_write(iocb->ki_filp, buf, count, &pos);
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else
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result = scullc_read(iocb->ki_filp, buf, count, &pos);
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/* If this is a synchronous IOCB, we return our status now. */
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if (is_sync_kiocb(iocb))
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return result;
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/* Otherwise defer the completion for a few milliseconds. */
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stuff = kmalloc (sizeof (*stuff), GFP_KERNEL);
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if (stuff == NULL)
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return result; /* No memory, just complete now */
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stuff->iocb = iocb;
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stuff->result = result;
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INIT_WORK(&stuff->work, scullc_do_deferred_op, stuff);
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schedule_delayed_work(&stuff->work, HZ/100);
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return -EIOCBQUEUED;
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}
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static ssize_t scullc_aio_read(struct kiocb *iocb, char __user *buf, size_t count,
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loff_t pos)
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{
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return scullc_defer_op(0, iocb, buf, count, pos);
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}
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static ssize_t scullc_aio_write(struct kiocb *iocb, const char __user *buf,
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size_t count, loff_t pos)
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{
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return scullc_defer_op(1, iocb, (char __user *) buf, count, pos);
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}
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/*
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* The fops
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*/
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struct file_operations scullc_fops = {
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.owner = THIS_MODULE,
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.llseek = scullc_llseek,
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.read = scullc_read,
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.write = scullc_write,
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.ioctl = scullc_ioctl,
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.open = scullc_open,
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.release = scullc_release,
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.aio_read = scullc_aio_read,
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.aio_write = scullc_aio_write,
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};
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int scullc_trim(struct scullc_dev *dev)
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{
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struct scullc_dev *next, *dptr;
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int qset = dev->qset; /* "dev" is not-null */
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int i;
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if (dev->vmas) /* don't trim: there are active mappings */
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return -EBUSY;
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for (dptr = dev; dptr; dptr = next) { /* all the list items */
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if (dptr->data) {
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for (i = 0; i < qset; i++)
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if (dptr->data[i])
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kmem_cache_free(scullc_cache, dptr->data[i]);
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kfree(dptr->data);
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dptr->data=NULL;
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}
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next=dptr->next;
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if (dptr != dev) kfree(dptr); /* all of them but the first */
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}
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dev->size = 0;
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dev->qset = scullc_qset;
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dev->quantum = scullc_quantum;
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dev->next = NULL;
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return 0;
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}
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static void scullc_setup_cdev(struct scullc_dev *dev, int index)
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{
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int err, devno = MKDEV(scullc_major, index);
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cdev_init(&dev->cdev, &scullc_fops);
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dev->cdev.owner = THIS_MODULE;
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dev->cdev.ops = &scullc_fops;
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err = cdev_add (&dev->cdev, devno, 1);
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/* Fail gracefully if need be */
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if (err)
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printk(KERN_NOTICE "Error %d adding scull%d", err, index);
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}
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/*
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* Finally, the module stuff
|
|
*/
|
|
|
|
int scullc_init(void)
|
|
{
|
|
int result, i;
|
|
dev_t dev = MKDEV(scullc_major, 0);
|
|
|
|
/*
|
|
* Register your major, and accept a dynamic number.
|
|
*/
|
|
if (scullc_major)
|
|
result = register_chrdev_region(dev, scullc_devs, "scullc");
|
|
else {
|
|
result = alloc_chrdev_region(&dev, 0, scullc_devs, "scullc");
|
|
scullc_major = MAJOR(dev);
|
|
}
|
|
if (result < 0)
|
|
return result;
|
|
|
|
|
|
/*
|
|
* allocate the devices -- we can't have them static, as the number
|
|
* can be specified at load time
|
|
*/
|
|
scullc_devices = kmalloc(scullc_devs*sizeof (struct scullc_dev), GFP_KERNEL);
|
|
if (!scullc_devices) {
|
|
result = -ENOMEM;
|
|
goto fail_malloc;
|
|
}
|
|
memset(scullc_devices, 0, scullc_devs*sizeof (struct scullc_dev));
|
|
for (i = 0; i < scullc_devs; i++) {
|
|
scullc_devices[i].quantum = scullc_quantum;
|
|
scullc_devices[i].qset = scullc_qset;
|
|
sema_init (&scullc_devices[i].sem, 1);
|
|
scullc_setup_cdev(scullc_devices + i, i);
|
|
}
|
|
|
|
scullc_cache = kmem_cache_create("scullc", scullc_quantum,
|
|
0, SLAB_HWCACHE_ALIGN, NULL, NULL); /* no ctor/dtor */
|
|
if (!scullc_cache) {
|
|
scullc_cleanup();
|
|
return -ENOMEM;
|
|
}
|
|
|
|
#ifdef SCULLC_USE_PROC /* only when available */
|
|
create_proc_read_entry("scullcmem", 0, NULL, scullc_read_procmem, NULL);
|
|
#endif
|
|
return 0; /* succeed */
|
|
|
|
fail_malloc:
|
|
unregister_chrdev_region(dev, scullc_devs);
|
|
return result;
|
|
}
|
|
|
|
|
|
|
|
void scullc_cleanup(void)
|
|
{
|
|
int i;
|
|
|
|
#ifdef SCULLC_USE_PROC
|
|
remove_proc_entry("scullcmem", NULL);
|
|
#endif
|
|
|
|
for (i = 0; i < scullc_devs; i++) {
|
|
cdev_del(&scullc_devices[i].cdev);
|
|
scullc_trim(scullc_devices + i);
|
|
}
|
|
kfree(scullc_devices);
|
|
|
|
if (scullc_cache)
|
|
kmem_cache_destroy(scullc_cache);
|
|
unregister_chrdev_region(MKDEV (scullc_major, 0), scullc_devs);
|
|
}
|
|
|
|
|
|
module_init(scullc_init);
|
|
module_exit(scullc_cleanup);
|