simple.c

/** Simple - REALLY simple memory mapping demonstration.** 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: simple.c,v 1.12 2005/01/31 16:15:31 rubini 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/mm.h>
#include <linux/kdev_t.h>
#include <asm/page.h>
#include <linux/cdev.h>#include <linux/device.h>static int simple_major = 0;
module_param(simple_major, int, 0);
MODULE_AUTHOR("Jonathan Corbet");
MODULE_LICENSE("Dual BSD/GPL");/** Open the device; in fact, there's nothing to do here.*/
static int simple_open (struct inode *inode, struct file *filp)
{return 0;
}/** Closing is just as simpler.*/
static int simple_release(struct inode *inode, struct file *filp)
{return 0;
}/** Common VMA ops.*/void simple_vma_open(struct vm_area_struct *vma)
{printk(KERN_NOTICE "Simple VMA open, virt %lx, phys %lx\n",vma->vm_start, vma->vm_pgoff << PAGE_SHIFT);
}void simple_vma_close(struct vm_area_struct *vma)
{printk(KERN_NOTICE "Simple VMA close.\n");
}/** The remap_pfn_range version of mmap.  This one is heavily borrowed* from drivers/char/mem.c.*/static struct vm_operations_struct simple_remap_vm_ops = {.open =  simple_vma_open,.close = simple_vma_close,
};static int simple_remap_mmap(struct file *filp, struct vm_area_struct *vma)
{if (remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,vma->vm_end - vma->vm_start,vma->vm_page_prot))return -EAGAIN;vma->vm_ops = &simple_remap_vm_ops;simple_vma_open(vma);return 0;
}/** The nopage version.*/
struct page *simple_vma_nopage(struct vm_area_struct *vma,unsigned long address, int *type)
{struct page *pageptr;unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;unsigned long physaddr = address - vma->vm_start + offset;unsigned long pageframe = physaddr >> PAGE_SHIFT;// Eventually remove these printksprintk (KERN_NOTICE "---- Nopage, off %lx phys %lx\n", offset, physaddr);printk (KERN_NOTICE "VA is %p\n", __va (physaddr));printk (KERN_NOTICE "Page at %p\n", virt_to_page (__va (physaddr)));if (!pfn_valid(pageframe))return NOPAGE_SIGBUS;pageptr = pfn_to_page(pageframe);printk (KERN_NOTICE "page->index = %ld mapping %p\n", pageptr->index, pageptr->mapping);printk (KERN_NOTICE "Page frame %ld\n", pageframe);get_page(pageptr);if (type)*type = VM_FAULT_MINOR;return pageptr;
}static struct vm_operations_struct simple_nopage_vm_ops = {.open =   simple_vma_open,.close =  simple_vma_close,.nopage = simple_vma_nopage,
};static int simple_nopage_mmap(struct file *filp, struct vm_area_struct *vma)
{unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;if (offset >= __pa(high_memory) || (filp->f_flags & O_SYNC))vma->vm_flags |= VM_IO;vma->vm_flags |= VM_RESERVED;vma->vm_ops = &simple_nopage_vm_ops;simple_vma_open(vma);return 0;
}/** Set up the cdev structure for a device.*/
static void simple_setup_cdev(struct cdev *dev, int minor,struct file_operations *fops)
{int err, devno = MKDEV(simple_major, minor);cdev_init(dev, fops);dev->owner = THIS_MODULE;dev->ops = fops;err = cdev_add (dev, devno, 1);/* Fail gracefully if need be */if (err)printk (KERN_NOTICE "Error %d adding simple%d", err, minor);
}/** Our various sub-devices.*/
/* Device 0 uses remap_pfn_range */
static struct file_operations simple_remap_ops = {.owner   = THIS_MODULE,.open    = simple_open,.release = simple_release,.mmap    = simple_remap_mmap,
};/* Device 1 uses nopage */
static struct file_operations simple_nopage_ops = {.owner   = THIS_MODULE,.open    = simple_open,.release = simple_release,.mmap    = simple_nopage_mmap,
};#define MAX_SIMPLE_DEV 2#if 0
static struct file_operations *simple_fops[MAX_SIMPLE_DEV] = {&simple_remap_ops,&simple_nopage_ops,
};
#endif/** We export two simple devices.  There's no need for us to maintain any* special housekeeping info, so we just deal with raw cdevs.*/
static struct cdev SimpleDevs[MAX_SIMPLE_DEV];/** Module housekeeping.*/
static int simple_init(void)
{int result;dev_t dev = MKDEV(simple_major, 0);/* Figure out our device number. */if (simple_major)result = register_chrdev_region(dev, 2, "simple");else {result = alloc_chrdev_region(&dev, 0, 2, "simple");simple_major = MAJOR(dev);}if (result < 0) {printk(KERN_WARNING "simple: unable to get major %d\n", simple_major);return result;}if (simple_major == 0)simple_major = result;/* Now set up two cdevs. */simple_setup_cdev(SimpleDevs, 0, &simple_remap_ops);simple_setup_cdev(SimpleDevs + 1, 1, &simple_nopage_ops);return 0;
}static void simple_cleanup(void)
{cdev_del(SimpleDevs);cdev_del(SimpleDevs + 1);unregister_chrdev_region(MKDEV(simple_major, 0), 2);
}module_init(simple_init);
module_exit(simple_cleanup);

simple_load

#!/bin/sh
module="simple"
device="simple"
mode="664"# Group: since distributions do it differently, look for wheel or use staff
if grep '^staff:' /etc/group > /dev/null; thengroup="staff"
elsegroup="wheel"
fi# invoke insmod with all arguments we got
# and use a pathname, as newer modutils don't look in . by default
/sbin/insmod -f ./$module.ko $* || exit 1major=`cat /proc/devices | awk "\\$2==\"$module\" {print \\$1}"`# Remove stale nodes and replace them, then give gid and perms
# Usually the script is shorter, it's simple that has several devices in it.rm -f /dev/${device}[rn]
mknod /dev/${device}r c $major 0
mknod /dev/${device}n c $major 1
chgrp $group /dev/${device}[rn]
chmod $mode  /dev/${device}[rn]

simple_unload

#!/bin/sh
module="simple"
device="simple"# invoke rmmod with all arguments we got
/sbin/rmmod $module $* || exit 1# Remove stale nodes
rm -f /dev/${device}[rn]

Makefile

# Comment/uncomment the following line to disable/enable debugging
#DEBUG = y# Add your debugging flag (or not) to CFLAGS
ifeq ($(DEBUG),y)DEBFLAGS = -O -g # "-O" is needed to expand inlines
elseDEBFLAGS = -O2
endifCFLAGS += $(DEBFLAGS) -I$(LDDINCDIR)ifneq ($(KERNELRELEASE),)
# call from kernel build systemobj-m    := simple.oelseKERNELDIR ?= /lib/modules/$(shell uname -r)/build
PWD       := $(shell pwd)default:$(MAKE) -C $(KERNELDIR) M=$(PWD) LDDINCDIR=$(PWD)/../include modulesendifclean:rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versionsdepend .depend dep:$(CC) $(CFLAGS) -M *.c > .dependifeq (.depend,$(wildcard .depend))
include .depend
endif

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一个Linux驱动：Simple - REALLY simple memory mapping demonstration.

simple.c

simple_load

simple_unload

Makefile

一个Linux驱动：Simple - REALLY simple memory mapping demonstration.相关推荐

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