[PATCH] s390: add vmcp interface

Add interface to issue VM control program commands.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 219 insertions, 0 deletions

diff --git a/drivers/s390/char/vmcp.c b/drivers/s390/char/vmcp.c
new file mode 100644
index 0000000..dfbbf23
--- /dev/null
+++ b/drivers/s390/char/vmcp.c
@@ -0,0 +1,219 @@
+/*
+ * Copyright (C) 2004,2005 IBM Corporation
+ * Interface implementation for communication with the v/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))
+		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 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", 0, 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);