[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 000000000000..dfbbf235ca2b
--- /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);