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-rw-r--r--scullp/main.c598
1 files changed, 598 insertions, 0 deletions
diff --git a/scullp/main.c b/scullp/main.c
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--- /dev/null
+++ b/scullp/main.c
@@ -0,0 +1,598 @@
+/* -*- C -*-
+ * main.c -- the bare scullp char module
+ *
+ * Copyright (C) 2001 Alessandro Rubini and Jonathan Corbet
+ * Copyright (C) 2001 O'Reilly & Associates
+ *
+ * The source code in this file can be freely used, adapted,
+ * and redistributed in source or binary form, so long as an
+ * acknowledgment appears in derived source files. The citation
+ * should list that the code comes from the book "Linux Device
+ * Drivers" by Alessandro Rubini and Jonathan Corbet, published
+ * by O'Reilly & Associates. No warranty is attached;
+ * we cannot take responsibility for errors or fitness for use.
+ *
+ * $Id: _main.c.in,v 1.21 2004/10/14 20:11:39 corbet Exp $
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/init.h>
+#include <linux/kernel.h> /* printk() */
+#include <linux/slab.h> /* kmalloc() */
+#include <linux/fs.h> /* everything... */
+#include <linux/errno.h> /* error codes */
+#include <linux/types.h> /* size_t */
+#include <linux/proc_fs.h>
+#include <linux/fcntl.h> /* O_ACCMODE */
+#include <linux/aio.h>
+#include <asm/uaccess.h>
+#include "scullp.h" /* local definitions */
+
+
+int scullp_major = SCULLP_MAJOR;
+int scullp_devs = SCULLP_DEVS; /* number of bare scullp devices */
+int scullp_qset = SCULLP_QSET;
+int scullp_order = SCULLP_ORDER;
+
+module_param(scullp_major, int, 0);
+module_param(scullp_devs, int, 0);
+module_param(scullp_qset, int, 0);
+module_param(scullp_order, int, 0);
+MODULE_AUTHOR("Alessandro Rubini");
+MODULE_LICENSE("Dual BSD/GPL");
+
+struct scullp_dev *scullp_devices; /* allocated in scullp_init */
+
+int scullp_trim(struct scullp_dev *dev);
+void scullp_cleanup(void);
+
+
+
+
+
+
+#ifdef SCULLP_USE_PROC /* don't waste space if unused */
+/*
+ * The proc filesystem: function to read and entry
+ */
+
+void scullp_proc_offset(char *buf, char **start, off_t *offset, int *len)
+{
+ if (*offset == 0)
+ return;
+ if (*offset >= *len) {
+ /* Not there yet */
+ *offset -= *len;
+ *len = 0;
+ } else {
+ /* We're into the interesting stuff now */
+ *start = buf + *offset;
+ *offset = 0;
+ }
+}
+
+/* FIXME: Do we need this here?? It be ugly */
+int scullp_read_procmem(char *buf, char **start, off_t offset,
+ int count, int *eof, void *data)
+{
+ int i, j, order, qset, len = 0;
+ int limit = count - 80; /* Don't print more than this */
+ struct scullp_dev *d;
+
+ *start = buf;
+ for(i = 0; i < scullp_devs; i++) {
+ d = &scullp_devices[i];
+ if (down_interruptible (&d->sem))
+ return -ERESTARTSYS;
+ qset = d->qset; /* retrieve the features of each device */
+ order = d->order;
+ len += sprintf(buf+len,"\nDevice %i: qset %i, order %i, sz %li\n",
+ i, qset, order, (long)(d->size));
+ for (; d; d = d->next) { /* scan the list */
+ len += sprintf(buf+len," item at %p, qset at %p\n",d,d->data);
+ scullp_proc_offset (buf, start, &offset, &len);
+ if (len > limit)
+ goto out;
+ if (d->data && !d->next) /* dump only the last item - save space */
+ for (j = 0; j < qset; j++) {
+ if (d->data[j])
+ len += sprintf(buf+len," % 4i:%8p\n",j,d->data[j]);
+ scullp_proc_offset (buf, start, &offset, &len);
+ if (len > limit)
+ goto out;
+ }
+ }
+ out:
+ up (&scullp_devices[i].sem);
+ if (len > limit)
+ break;
+ }
+ *eof = 1;
+ return len;
+}
+
+#endif /* SCULLP_USE_PROC */
+
+/*
+ * Open and close
+ */
+
+int scullp_open (struct inode *inode, struct file *filp)
+{
+ struct scullp_dev *dev; /* device information */
+
+ /* Find the device */
+ dev = container_of(inode->i_cdev, struct scullp_dev, cdev);
+
+ /* now trim to 0 the length of the device if open was write-only */
+ if ( (filp->f_flags & O_ACCMODE) == O_WRONLY) {
+ if (down_interruptible (&dev->sem))
+ return -ERESTARTSYS;
+ scullp_trim(dev); /* ignore errors */
+ up (&dev->sem);
+ }
+
+ /* and use filp->private_data to point to the device data */
+ filp->private_data = dev;
+
+ return 0; /* success */
+}
+
+int scullp_release (struct inode *inode, struct file *filp)
+{
+ return 0;
+}
+
+/*
+ * Follow the list
+ */
+struct scullp_dev *scullp_follow(struct scullp_dev *dev, int n)
+{
+ while (n--) {
+ if (!dev->next) {
+ dev->next = kmalloc(sizeof(struct scullp_dev), GFP_KERNEL);
+ memset(dev->next, 0, sizeof(struct scullp_dev));
+ }
+ dev = dev->next;
+ continue;
+ }
+ return dev;
+}
+
+/*
+ * Data management: read and write
+ */
+
+ssize_t scullp_read (struct file *filp, char __user *buf, size_t count,
+ loff_t *f_pos)
+{
+ struct scullp_dev *dev = filp->private_data; /* the first listitem */
+ struct scullp_dev *dptr;
+ int quantum = PAGE_SIZE << dev->order;
+ int qset = dev->qset;
+ int itemsize = quantum * qset; /* how many bytes in the listitem */
+ int item, s_pos, q_pos, rest;
+ ssize_t retval = 0;
+
+ if (down_interruptible (&dev->sem))
+ return -ERESTARTSYS;
+ if (*f_pos > dev->size)
+ goto nothing;
+ if (*f_pos + count > dev->size)
+ count = dev->size - *f_pos;
+ /* find listitem, qset index, and offset in the quantum */
+ item = ((long) *f_pos) / itemsize;
+ rest = ((long) *f_pos) % itemsize;
+ s_pos = rest / quantum; q_pos = rest % quantum;
+
+ /* follow the list up to the right position (defined elsewhere) */
+ dptr = scullp_follow(dev, item);
+
+ if (!dptr->data)
+ goto nothing; /* don't fill holes */
+ if (!dptr->data[s_pos])
+ goto nothing;
+ if (count > quantum - q_pos)
+ count = quantum - q_pos; /* read only up to the end of this quantum */
+
+ if (copy_to_user (buf, dptr->data[s_pos]+q_pos, count)) {
+ retval = -EFAULT;
+ goto nothing;
+ }
+ up (&dev->sem);
+
+ *f_pos += count;
+ return count;
+
+ nothing:
+ up (&dev->sem);
+ return retval;
+}
+
+
+
+ssize_t scullp_write (struct file *filp, const char __user *buf, size_t count,
+ loff_t *f_pos)
+{
+ struct scullp_dev *dev = filp->private_data;
+ struct scullp_dev *dptr;
+ int quantum = PAGE_SIZE << dev->order;
+ int qset = dev->qset;
+ int itemsize = quantum * qset;
+ int item, s_pos, q_pos, rest;
+ ssize_t retval = -ENOMEM; /* our most likely error */
+
+ if (down_interruptible (&dev->sem))
+ return -ERESTARTSYS;
+
+ /* find listitem, qset index and offset in the quantum */
+ item = ((long) *f_pos) / itemsize;
+ rest = ((long) *f_pos) % itemsize;
+ s_pos = rest / quantum; q_pos = rest % quantum;
+
+ /* follow the list up to the right position */
+ dptr = scullp_follow(dev, item);
+ if (!dptr->data) {
+ dptr->data = kmalloc(qset * sizeof(void *), GFP_KERNEL);
+ if (!dptr->data)
+ goto nomem;
+ memset(dptr->data, 0, qset * sizeof(char *));
+ }
+ /* Here's the allocation of a single quantum */
+ if (!dptr->data[s_pos]) {
+ dptr->data[s_pos] =
+ (void *)__get_free_pages(GFP_KERNEL, dptr->order);
+ if (!dptr->data[s_pos])
+ goto nomem;
+ memset(dptr->data[s_pos], 0, PAGE_SIZE << dptr->order);
+ }
+ if (count > quantum - q_pos)
+ count = quantum - q_pos; /* write only up to the end of this quantum */
+ if (copy_from_user (dptr->data[s_pos]+q_pos, buf, count)) {
+ retval = -EFAULT;
+ goto nomem;
+ }
+ *f_pos += count;
+
+ /* update the size */
+ if (dev->size < *f_pos)
+ dev->size = *f_pos;
+ up (&dev->sem);
+ return count;
+
+ nomem:
+ up (&dev->sem);
+ return retval;
+}
+
+/*
+ * The ioctl() implementation
+ */
+
+int scullp_ioctl (struct inode *inode, struct file *filp,
+ unsigned int cmd, unsigned long arg)
+{
+
+ int err = 0, ret = 0, tmp;
+
+ /* don't even decode wrong cmds: better returning ENOTTY than EFAULT */
+ if (_IOC_TYPE(cmd) != SCULLP_IOC_MAGIC) return -ENOTTY;
+ if (_IOC_NR(cmd) > SCULLP_IOC_MAXNR) return -ENOTTY;
+
+ /*
+ * the type is a bitmask, and VERIFY_WRITE catches R/W
+ * transfers. Note that the type is user-oriented, while
+ * verify_area is kernel-oriented, so the concept of "read" and
+ * "write" is reversed
+ */
+ if (_IOC_DIR(cmd) & _IOC_READ)
+ err = !access_ok(VERIFY_WRITE, (void __user *)arg, _IOC_SIZE(cmd));
+ else if (_IOC_DIR(cmd) & _IOC_WRITE)
+ err = !access_ok(VERIFY_READ, (void __user *)arg, _IOC_SIZE(cmd));
+ if (err)
+ return -EFAULT;
+
+ switch(cmd) {
+
+ case SCULLP_IOCRESET:
+ scullp_qset = SCULLP_QSET;
+ scullp_order = SCULLP_ORDER;
+ break;
+
+ case SCULLP_IOCSORDER: /* Set: arg points to the value */
+ ret = __get_user(scullp_order, (int __user *) arg);
+ break;
+
+ case SCULLP_IOCTORDER: /* Tell: arg is the value */
+ scullp_order = arg;
+ break;
+
+ case SCULLP_IOCGORDER: /* Get: arg is pointer to result */
+ ret = __put_user (scullp_order, (int __user *) arg);
+ break;
+
+ case SCULLP_IOCQORDER: /* Query: return it (it's positive) */
+ return scullp_order;
+
+ case SCULLP_IOCXORDER: /* eXchange: use arg as pointer */
+ tmp = scullp_order;
+ ret = __get_user(scullp_order, (int __user *) arg);
+ if (ret == 0)
+ ret = __put_user(tmp, (int __user *) arg);
+ break;
+
+ case SCULLP_IOCHORDER: /* sHift: like Tell + Query */
+ tmp = scullp_order;
+ scullp_order = arg;
+ return tmp;
+
+ case SCULLP_IOCSQSET:
+ ret = __get_user(scullp_qset, (int __user *) arg);
+ break;
+
+ case SCULLP_IOCTQSET:
+ scullp_qset = arg;
+ break;
+
+ case SCULLP_IOCGQSET:
+ ret = __put_user(scullp_qset, (int __user *)arg);
+ break;
+
+ case SCULLP_IOCQQSET:
+ return scullp_qset;
+
+ case SCULLP_IOCXQSET:
+ tmp = scullp_qset;
+ ret = __get_user(scullp_qset, (int __user *)arg);
+ if (ret == 0)
+ ret = __put_user(tmp, (int __user *)arg);
+ break;
+
+ case SCULLP_IOCHQSET:
+ tmp = scullp_qset;
+ scullp_qset = arg;
+ return tmp;
+
+ default: /* redundant, as cmd was checked against MAXNR */
+ return -ENOTTY;
+ }
+
+ return ret;
+}
+
+/*
+ * The "extended" operations
+ */
+
+loff_t scullp_llseek (struct file *filp, loff_t off, int whence)
+{
+ struct scullp_dev *dev = filp->private_data;
+ long newpos;
+
+ switch(whence) {
+ case 0: /* SEEK_SET */
+ newpos = off;
+ break;
+
+ case 1: /* SEEK_CUR */
+ newpos = filp->f_pos + off;
+ break;
+
+ case 2: /* SEEK_END */
+ newpos = dev->size + off;
+ break;
+
+ default: /* can't happen */
+ return -EINVAL;
+ }
+ if (newpos<0) return -EINVAL;
+ filp->f_pos = newpos;
+ return newpos;
+}
+
+
+/*
+ * A simple asynchronous I/O implementation.
+ */
+
+struct async_work {
+ struct kiocb *iocb;
+ int result;
+ struct work_struct work;
+};
+
+/*
+ * "Complete" an asynchronous operation.
+ */
+static void scullp_do_deferred_op(void *p)
+{
+ struct async_work *stuff = (struct async_work *) p;
+ aio_complete(stuff->iocb, stuff->result, 0);
+ kfree(stuff);
+}
+
+
+static int scullp_defer_op(int write, struct kiocb *iocb, char __user *buf,
+ size_t count, loff_t pos)
+{
+ struct async_work *stuff;
+ int result;
+
+ /* Copy now while we can access the buffer */
+ if (write)
+ result = scullp_write(iocb->ki_filp, buf, count, &pos);
+ else
+ result = scullp_read(iocb->ki_filp, buf, count, &pos);
+
+ /* If this is a synchronous IOCB, we return our status now. */
+ if (is_sync_kiocb(iocb))
+ return result;
+
+ /* Otherwise defer the completion for a few milliseconds. */
+ stuff = kmalloc (sizeof (*stuff), GFP_KERNEL);
+ if (stuff == NULL)
+ return result; /* No memory, just complete now */
+ stuff->iocb = iocb;
+ stuff->result = result;
+ INIT_WORK(&stuff->work, scullp_do_deferred_op, stuff);
+ schedule_delayed_work(&stuff->work, HZ/100);
+ return -EIOCBQUEUED;
+}
+
+
+static ssize_t scullp_aio_read(struct kiocb *iocb, char __user *buf, size_t count,
+ loff_t pos)
+{
+ return scullp_defer_op(0, iocb, buf, count, pos);
+}
+
+static ssize_t scullp_aio_write(struct kiocb *iocb, const char __user *buf,
+ size_t count, loff_t pos)
+{
+ return scullp_defer_op(1, iocb, (char __user *) buf, count, pos);
+}
+
+
+
+/*
+ * Mmap *is* available, but confined in a different file
+ */
+extern int scullp_mmap(struct file *filp, struct vm_area_struct *vma);
+
+
+/*
+ * The fops
+ */
+
+struct file_operations scullp_fops = {
+ .owner = THIS_MODULE,
+ .llseek = scullp_llseek,
+ .read = scullp_read,
+ .write = scullp_write,
+ .ioctl = scullp_ioctl,
+ .mmap = scullp_mmap,
+ .open = scullp_open,
+ .release = scullp_release,
+ .aio_read = scullp_aio_read,
+ .aio_write = scullp_aio_write,
+};
+
+int scullp_trim(struct scullp_dev *dev)
+{
+ struct scullp_dev *next, *dptr;
+ int qset = dev->qset; /* "dev" is not-null */
+ int i;
+
+ if (dev->vmas) /* don't trim: there are active mappings */
+ return -EBUSY;
+
+ for (dptr = dev; dptr; dptr = next) { /* all the list items */
+ if (dptr->data) {
+ /* This code frees a whole quantum-set */
+ for (i = 0; i < qset; i++)
+ if (dptr->data[i])
+ free_pages((unsigned long)(dptr->data[i]),
+ dptr->order);
+
+ kfree(dptr->data);
+ dptr->data=NULL;
+ }
+ next=dptr->next;
+ if (dptr != dev) kfree(dptr); /* all of them but the first */
+ }
+ dev->size = 0;
+ dev->qset = scullp_qset;
+ dev->order = scullp_order;
+ dev->next = NULL;
+ return 0;
+}
+
+
+static void scullp_setup_cdev(struct scullp_dev *dev, int index)
+{
+ int err, devno = MKDEV(scullp_major, index);
+
+ cdev_init(&dev->cdev, &scullp_fops);
+ dev->cdev.owner = THIS_MODULE;
+ dev->cdev.ops = &scullp_fops;
+ err = cdev_add (&dev->cdev, devno, 1);
+ /* Fail gracefully if need be */
+ if (err)
+ printk(KERN_NOTICE "Error %d adding scull%d", err, index);
+}
+
+
+
+/*
+ * Finally, the module stuff
+ */
+
+int scullp_init(void)
+{
+ int result, i;
+ dev_t dev = MKDEV(scullp_major, 0);
+
+ /*
+ * Register your major, and accept a dynamic number.
+ */
+ if (scullp_major)
+ result = register_chrdev_region(dev, scullp_devs, "scullp");
+ else {
+ result = alloc_chrdev_region(&dev, 0, scullp_devs, "scullp");
+ scullp_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
+ */
+ scullp_devices = kmalloc(scullp_devs*sizeof (struct scullp_dev), GFP_KERNEL);
+ if (!scullp_devices) {
+ result = -ENOMEM;
+ goto fail_malloc;
+ }
+ memset(scullp_devices, 0, scullp_devs*sizeof (struct scullp_dev));
+ for (i = 0; i < scullp_devs; i++) {
+ scullp_devices[i].order = scullp_order;
+ scullp_devices[i].qset = scullp_qset;
+ sema_init (&scullp_devices[i].sem, 1);
+ scullp_setup_cdev(scullp_devices + i, i);
+ }
+
+
+#ifdef SCULLP_USE_PROC /* only when available */
+ create_proc_read_entry("scullpmem", 0, NULL, scullp_read_procmem, NULL);
+#endif
+ return 0; /* succeed */
+
+ fail_malloc:
+ unregister_chrdev_region(dev, scullp_devs);
+ return result;
+}
+
+
+
+void scullp_cleanup(void)
+{
+ int i;
+
+#ifdef SCULLP_USE_PROC
+ remove_proc_entry("scullpmem", NULL);
+#endif
+
+ for (i = 0; i < scullp_devs; i++) {
+ cdev_del(&scullp_devices[i].cdev);
+ scullp_trim(scullp_devices + i);
+ }
+ kfree(scullp_devices);
+ unregister_chrdev_region(MKDEV (scullp_major, 0), scullp_devs);
+}
+
+
+module_init(scullp_init);
+module_exit(scullp_cleanup);
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