2 * Copyright IBM Corp. 2004,2007
3 * Interface implementation for communication with the z/VM control program
4 * Author(s): Christian Borntraeger <borntraeger@de.ibm.com>
7 * z/VMs CP offers the possibility to issue commands via the diagnose code 8
8 * this driver implements a character device that issues these commands and
9 * returns the answer of CP.
11 * The idea of this driver is based on cpint from Neale Ferguson and #CP in CMS
15 #include <linux/init.h>
16 #include <linux/kernel.h>
17 #include <linux/miscdevice.h>
18 #include <linux/module.h>
19 #include <asm/cpcmd.h>
20 #include <asm/debug.h>
21 #include <asm/uaccess.h>
24 MODULE_LICENSE("GPL");
25 MODULE_AUTHOR("Christian Borntraeger <borntraeger@de.ibm.com>");
26 MODULE_DESCRIPTION("z/VM CP interface");
28 #define PRINTK_HEADER "vmcp: "
30 static debug_info_t *vmcp_debug;
32 static int vmcp_open(struct inode *inode, struct file *file)
34 struct vmcp_session *session;
36 if (!capable(CAP_SYS_ADMIN))
39 session = kmalloc(sizeof(*session), GFP_KERNEL);
43 session->bufsize = PAGE_SIZE;
44 session->response = NULL;
45 session->resp_size = 0;
46 mutex_init(&session->mutex);
47 file->private_data = session;
48 return nonseekable_open(inode, file);
51 static int vmcp_release(struct inode *inode, struct file *file)
53 struct vmcp_session *session;
55 session = (struct vmcp_session *)file->private_data;
56 file->private_data = NULL;
57 free_pages((unsigned long)session->response, get_order(session->bufsize));
63 vmcp_read(struct file *file, char __user *buff, size_t count, loff_t *ppos)
67 struct vmcp_session *session;
69 session = file->private_data;
70 if (mutex_lock_interruptible(&session->mutex))
72 if (!session->response) {
73 mutex_unlock(&session->mutex);
76 size = min_t(size_t, session->resp_size, session->bufsize);
77 ret = simple_read_from_buffer(buff, count, ppos,
78 session->response, size);
80 mutex_unlock(&session->mutex);
86 vmcp_write(struct file *file, const char __user *buff, size_t count,
90 struct vmcp_session *session;
94 cmd = kmalloc(count + 1, GFP_KERNEL);
97 if (copy_from_user(cmd, buff, count)) {
102 session = (struct vmcp_session *)file->private_data;
103 if (mutex_lock_interruptible(&session->mutex)) {
107 if (!session->response)
108 session->response = (char *)__get_free_pages(GFP_KERNEL
109 | __GFP_REPEAT | GFP_DMA,
110 get_order(session->bufsize));
111 if (!session->response) {
112 mutex_unlock(&session->mutex);
116 debug_text_event(vmcp_debug, 1, cmd);
117 session->resp_size = cpcmd(cmd, session->response, session->bufsize,
118 &session->resp_code);
119 mutex_unlock(&session->mutex);
121 *ppos = 0; /* reset the file pointer after a command */
127 * These ioctls are available, as the semantics of the diagnose 8 call
128 * does not fit very well into a Linux call. Diagnose X'08' is described in
129 * CP Programming Services SC24-6084-00
131 * VMCP_GETCODE: gives the CP return code back to user space
132 * VMCP_SETBUF: sets the response buffer for the next write call. diagnose 8
133 * expects adjacent pages in real storage and to make matters worse, we
134 * dont know the size of the response. Therefore we default to PAGESIZE and
135 * let userspace to change the response size, if userspace expects a bigger
138 static long vmcp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
140 struct vmcp_session *session;
143 session = (struct vmcp_session *)file->private_data;
144 if (mutex_lock_interruptible(&session->mutex))
148 temp = session->resp_code;
149 mutex_unlock(&session->mutex);
150 return put_user(temp, (int __user *)arg);
152 free_pages((unsigned long)session->response,
153 get_order(session->bufsize));
154 session->response=NULL;
155 temp = get_user(session->bufsize, (int __user *)arg);
156 if (get_order(session->bufsize) > 8) {
157 session->bufsize = PAGE_SIZE;
160 mutex_unlock(&session->mutex);
163 temp = session->resp_size;
164 mutex_unlock(&session->mutex);
165 return put_user(temp, (int __user *)arg);
167 mutex_unlock(&session->mutex);
172 static const struct file_operations vmcp_fops = {
173 .owner = THIS_MODULE,
175 .release = vmcp_release,
178 .unlocked_ioctl = vmcp_ioctl,
179 .compat_ioctl = vmcp_ioctl,
182 static struct miscdevice vmcp_dev = {
184 .minor = MISC_DYNAMIC_MINOR,
188 static int __init vmcp_init(void)
192 if (!MACHINE_IS_VM) {
193 PRINT_WARN("z/VM CP interface is only available under z/VM\n");
197 vmcp_debug = debug_register("vmcp", 1, 1, 240);
201 ret = debug_register_view(vmcp_debug, &debug_hex_ascii_view);
203 debug_unregister(vmcp_debug);
207 ret = misc_register(&vmcp_dev);
209 debug_unregister(vmcp_debug);
216 static void __exit vmcp_exit(void)
218 misc_deregister(&vmcp_dev);
219 debug_unregister(vmcp_debug);
222 module_init(vmcp_init);
223 module_exit(vmcp_exit);