/* -*- 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);