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/*
* Copyright (C) 2004,2005 IBM Corporation
* Interface implementation for communication with the z/VM control program
* Author(s): Christian Borntraeger <cborntra@de.ibm.com>
*
*
* z/VMs CP offers the possibility to issue commands via the diagnose code 8
* this driver implements a character device that issues these commands and
* returns the answer of CP.
* The idea of this driver is based on cpint from Neale Ferguson and #CP in CMS
*/
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <asm/cpcmd.h>
#include <asm/debug.h>
#include <asm/uaccess.h>
#include "vmcp.h"
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Christian Borntraeger <cborntra@de.ibm.com>");
MODULE_DESCRIPTION("z/VM CP interface");
static debug_info_t *vmcp_debug;
static int vmcp_open(struct inode *inode, struct file *file)
{
struct vmcp_session *session;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
session = kmalloc(sizeof(*session), GFP_KERNEL);
if (!session)
return -ENOMEM;
session->bufsize = PAGE_SIZE;
session->response = NULL;
session->resp_size = 0;
init_MUTEX(&session->mutex);
file->private_data = session;
return nonseekable_open(inode, file);
}
static int vmcp_release(struct inode *inode, struct file *file)
{
struct vmcp_session *session;
session = (struct vmcp_session *)file->private_data;
file->private_data = NULL;
free_pages((unsigned long)session->response, get_order(session->bufsize));
kfree(session);
return 0;
}
static ssize_t
vmcp_read(struct file *file, char __user * buff, size_t count, loff_t * ppos)
{
size_t tocopy;
struct vmcp_session *session;
session = (struct vmcp_session *)file->private_data;
if (down_interruptible(&session->mutex))
return -ERESTARTSYS;
if (!session->response) {
up(&session->mutex);
return 0;
}
if (*ppos > session->resp_size) {
up(&session->mutex);
return 0;
}
tocopy = min(session->resp_size - (size_t) (*ppos), count);
tocopy = min(tocopy,session->bufsize - (size_t) (*ppos));
if (copy_to_user(buff, session->response + (*ppos), tocopy)) {
up(&session->mutex);
return -EFAULT;
}
up(&session->mutex);
*ppos += tocopy;
return tocopy;
}
static ssize_t
vmcp_write(struct file *file, const char __user * buff, size_t count,
loff_t * ppos)
{
char *cmd;
struct vmcp_session *session;
if (count > 240)
return -EINVAL;
cmd = kmalloc(count + 1, GFP_KERNEL);
if (!cmd)
return -ENOMEM;
if (copy_from_user(cmd, buff, count)) {
kfree(cmd);
return -EFAULT;
}
cmd[count] = '\0';
session = (struct vmcp_session *)file->private_data;
if (down_interruptible(&session->mutex)) {
kfree(cmd);
return -ERESTARTSYS;
}
if (!session->response)
session->response = (char *)__get_free_pages(GFP_KERNEL
| __GFP_REPEAT | GFP_DMA,
get_order(session->bufsize));
if (!session->response) {
up(&session->mutex);
kfree(cmd);
return -ENOMEM;
}
debug_text_event(vmcp_debug, 1, cmd);
session->resp_size = cpcmd(cmd, session->response,
session->bufsize,
&session->resp_code);
up(&session->mutex);
kfree(cmd);
*ppos = 0; /* reset the file pointer after a command */
return count;
}
/*
* These ioctls are available, as the semantics of the diagnose 8 call
* does not fit very well into a Linux call. Diagnose X'08' is described in
* CP Programming Services SC24-6084-00
*
* VMCP_GETCODE: gives the CP return code back to user space
* VMCP_SETBUF: sets the response buffer for the next write call. diagnose 8
* expects adjacent pages in real storage and to make matters worse, we
* dont know the size of the response. Therefore we default to PAGESIZE and
* let userspace to change the response size, if userspace expects a bigger
* response
*/
static long vmcp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct vmcp_session *session;
int temp;
session = (struct vmcp_session *)file->private_data;
if (down_interruptible(&session->mutex))
return -ERESTARTSYS;
switch (cmd) {
case VMCP_GETCODE:
temp = session->resp_code;
up(&session->mutex);
return put_user(temp, (int __user *)arg);
case VMCP_SETBUF:
free_pages((unsigned long)session->response,
get_order(session->bufsize));
session->response=NULL;
temp = get_user(session->bufsize, (int __user *)arg);
if (get_order(session->bufsize) > 8) {
session->bufsize = PAGE_SIZE;
temp = -EINVAL;
}
up(&session->mutex);
return temp;
case VMCP_GETSIZE:
temp = session->resp_size;
up(&session->mutex);
return put_user(temp, (int __user *)arg);
default:
up(&session->mutex);
return -ENOIOCTLCMD;
}
}
static const struct file_operations vmcp_fops = {
.owner = THIS_MODULE,
.open = &vmcp_open,
.release = &vmcp_release,
.read = &vmcp_read,
.llseek = &no_llseek,
.write = &vmcp_write,
.unlocked_ioctl = &vmcp_ioctl,
.compat_ioctl = &vmcp_ioctl
};
static struct miscdevice vmcp_dev = {
.name = "vmcp",
.minor = MISC_DYNAMIC_MINOR,
.fops = &vmcp_fops,
};
static int __init vmcp_init(void)
{
int ret;
if (!MACHINE_IS_VM) {
printk(KERN_WARNING
"z/VM CP interface is only available under z/VM\n");
return -ENODEV;
}
ret = misc_register(&vmcp_dev);
if (!ret)
printk(KERN_INFO "z/VM CP interface loaded\n");
else
printk(KERN_WARNING
"z/VM CP interface not loaded. Could not register misc device.\n");
vmcp_debug = debug_register("vmcp", 1, 1, 240);
debug_register_view(vmcp_debug, &debug_hex_ascii_view);
return ret;
}
static void __exit vmcp_exit(void)
{
WARN_ON(misc_deregister(&vmcp_dev) != 0);
debug_unregister(vmcp_debug);
printk(KERN_INFO "z/VM CP interface unloaded.\n");
}
module_init(vmcp_init);
module_exit(vmcp_exit);
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