s390/sclp: Add SCLP character device driver

Add a character misc device "sclp_ctl" that allows to run SCCBs
from user space using the SCLP_CTL_SCCB ioctl.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 145 insertions, 0 deletions

diff --git a/drivers/s390/char/sclp_ctl.c b/drivers/s390/char/sclp_ctl.c
new file mode 100644
index 000000000000..abe8ef13d148
--- /dev/null
+++ b/drivers/s390/char/sclp_ctl.c
@@ -0,0 +1,145 @@
+/*
+ * IOCTL interface for SCLP
+ *
+ * Copyright IBM Corp. 2012
+ *
+ * Author: Michael Holzheu <holzheu@linux.vnet.ibm.com>
+ */
+
+#include <linux/compat.h>
+#include <linux/uaccess.h>
+#include <linux/miscdevice.h>
+#include <linux/gfp.h>
+#include <linux/module.h>
+#include <linux/ioctl.h>
+#include <linux/fs.h>
+#include <linux/compat.h>
+#include <asm/compat.h>
+#include <asm/sclp_ctl.h>
+#include <asm/sclp.h>
+
+#include "sclp.h"
+
+/*
+ * Supported command words
+ */
+static unsigned int sclp_ctl_sccb_wlist[] = {
+        0x00400002,
+        0x00410002,
+};
+
+/*
+ * Check if command word is supported
+ */
+static int sclp_ctl_cmdw_supported(unsigned int cmdw)
+{
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(sclp_ctl_sccb_wlist); i++) {
+                if (cmdw == sclp_ctl_sccb_wlist[i])
+                        return 1;
+        }
+        return 0;
+}
+
+static void __user *u64_to_uptr(u64 value)
+{
+        if (is_compat_task())
+                return compat_ptr(value);
+        else
+                return (void __user *)(unsigned long)value;
+}
+
+/*
+ * Start SCLP request
+ */
+static int sclp_ctl_ioctl_sccb(void __user *user_area)
+{
+        struct sclp_ctl_sccb ctl_sccb;
+        struct sccb_header *sccb;
+        int rc;
+
+        if (copy_from_user(&ctl_sccb, user_area, sizeof(ctl_sccb)))
+                return -EFAULT;
+        if (!sclp_ctl_cmdw_supported(ctl_sccb.cmdw))
+                return -EOPNOTSUPP;
+        sccb = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
+        if (!sccb)
+                return -ENOMEM;
+        if (copy_from_user(sccb, u64_to_uptr(ctl_sccb.sccb), sizeof(*sccb))) {
+                rc = -EFAULT;
+                goto out_free;
+        }
+        if (sccb->length > PAGE_SIZE || sccb->length < 8)
+                return -EINVAL;
+        if (copy_from_user(sccb, u64_to_uptr(ctl_sccb.sccb), sccb->length)) {
+                rc = -EFAULT;
+                goto out_free;
+        }
+        rc = sclp_sync_request(ctl_sccb.cmdw, sccb);
+        if (rc)
+                goto out_free;
+        if (copy_to_user(u64_to_uptr(ctl_sccb.sccb), sccb, sccb->length))
+                rc = -EFAULT;
+out_free:
+        free_page((unsigned long) sccb);
+        return rc;
+}
+
+/*
+ * SCLP SCCB ioctl function
+ */
+static long sclp_ctl_ioctl(struct file *filp, unsigned int cmd,
+                           unsigned long arg)
+{
+        void __user *argp;
+
+        if (is_compat_task())
+                argp = compat_ptr(arg);
+        else
+                argp = (void __user *) arg;
+        switch (cmd) {
+        case SCLP_CTL_SCCB:
+                return sclp_ctl_ioctl_sccb(argp);
+        default: /* unknown ioctl number */
+                return -ENOTTY;
+        }
+}
+
+/*
+ * File operations
+ */
+static const struct file_operations sclp_ctl_fops = {
+        .owner = THIS_MODULE,
+        .open = nonseekable_open,
+        .unlocked_ioctl = sclp_ctl_ioctl,
+        .compat_ioctl = sclp_ctl_ioctl,
+        .llseek = no_llseek,
+};
+
+/*
+ * Misc device definition
+ */
+static struct miscdevice sclp_ctl_device = {
+        .minor = MISC_DYNAMIC_MINOR,
+        .name = "sclp",
+        .fops = &sclp_ctl_fops,
+};
+
+/*
+ * Register sclp_ctl misc device
+ */
+static int __init sclp_ctl_init(void)
+{
+        return misc_register(&sclp_ctl_device);
+}
+module_init(sclp_ctl_init);
+
+/*
+ * Deregister sclp_ctl misc device
+ */
+static void __exit sclp_ctl_exit(void)
+{
+        misc_deregister(&sclp_ctl_device);
+}
+module_exit(sclp_ctl_exit);