arch/powerpc/platforms/pseries/scanlog.c

   1 /*
   2  *  c 2001 PPC 64 Team, IBM Corp
   3  *
   4  *      This program is free software; you can redistribute it and/or
   5  *      modify it under the terms of the GNU General Public License
   6  *      as published by the Free Software Foundation; either version
   7  *      2 of the License, or (at your option) any later version.
   8  *
   9  * scan-log-data driver for PPC64  Todd Inglett <tinglett@vnet.ibm.com>
  10  *
  11  * When ppc64 hardware fails the service processor dumps internal state
  12  * of the system.  After a reboot the operating system can access a dump
  13  * of this data using this driver.  A dump exists if the device-tree
  14  * /chosen/ibm,scan-log-data property exists.
  15  *
  16  * This driver exports /proc/ppc64/scan-log-dump which can be read.
  17  * The driver supports only sequential reads.
  18  *
  19  * The driver looks at a write to the driver for the single word "reset".
  20  * If given, the driver will reset the scanlog so the platform can free it.
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/types.h>
  25 #include <linux/errno.h>
  26 #include <linux/proc_fs.h>
  27 #include <linux/init.h>
  28 #include <linux/delay.h>
  29 #include <asm/uaccess.h>
  30 #include <asm/rtas.h>
  31 #include <asm/prom.h>
  32
  33 #define MODULE_VERS "1.0"
  34 #define MODULE_NAME "scanlog"
  35
  36 /* Status returns from ibm,scan-log-dump */
  37 #define SCANLOG_COMPLETE 0
  38 #define SCANLOG_HWERROR -1
  39 #define SCANLOG_CONTINUE 1
  40
  41 #define DEBUG(A...) do { if (scanlog_debug) printk(KERN_ERR "scanlog: " A); } while (0)
  42
  43 static int scanlog_debug;
  44 static unsigned int ibm_scan_log_dump;                  /* RTAS token */
  45 static struct proc_dir_entry *proc_ppc64_scan_log_dump; /* The proc file */
  46
  47 static ssize_t scanlog_read(struct file *file, char __user *buf,
  48                             size_t count, loff_t *ppos)
  49 {
  50         struct inode * inode = file->f_path.dentry->d_inode;
  51         struct proc_dir_entry *dp;
  52         unsigned int *data;
  53         int status;
  54         unsigned long len, off;
  55         unsigned int wait_time;
  56
  57         dp = PDE(inode);
  58         data = (unsigned int *)dp->data;
  59
  60         if (!data) {
  61                 printk(KERN_ERR "scanlog: read failed no data\n");
  62                 return -EIO;
  63         }
  64
  65         if (count > RTAS_DATA_BUF_SIZE)
  66                 count = RTAS_DATA_BUF_SIZE;
  67
  68         if (count < 1024) {
  69                 /* This is the min supported by this RTAS call.  Rather
  70                  * than do all the buffering we insist the user code handle
  71                  * larger reads.  As long as cp works... :)
  72                  */
  73                 printk(KERN_ERR "scanlog: cannot perform a small read (%ld)\n", count);
  74                 return -EINVAL;
  75         }
  76
  77         if (!access_ok(VERIFY_WRITE, buf, count))
  78                 return -EFAULT;
  79
  80         for (;;) {
  81                 wait_time = 500;        /* default wait if no data */
  82                 spin_lock(&rtas_data_buf_lock);
  83                 memcpy(rtas_data_buf, data, RTAS_DATA_BUF_SIZE);
  84                 status = rtas_call(ibm_scan_log_dump, 2, 1, NULL,
  85                                    (u32) __pa(rtas_data_buf), (u32) count);
  86                 memcpy(data, rtas_data_buf, RTAS_DATA_BUF_SIZE);
  87                 spin_unlock(&rtas_data_buf_lock);
  88
  89                 DEBUG("status=%d, data[0]=%x, data[1]=%x, data[2]=%x\n",
  90                       status, data[0], data[1], data[2]);
  91                 switch (status) {
  92                     case SCANLOG_COMPLETE:
  93                         DEBUG("hit eof\n");
  94                         return 0;
  95                     case SCANLOG_HWERROR:
  96                         DEBUG("hardware error reading scan log data\n");
  97                         return -EIO;
  98                     case SCANLOG_CONTINUE:
  99                         /* We may or may not have data yet */
 100                         len = data[1];
 101                         off = data[2];
 102                         if (len > 0) {
 103                                 if (copy_to_user(buf, ((char *)data)+off, len))
 104                                         return -EFAULT;
 105                                 return len;
 106                         }
 107                         /* Break to sleep default time */
 108                         break;
 109                     default:
 110                         /* Assume extended busy */
 111                         wait_time = rtas_busy_delay_time(status);
 112                         if (!wait_time) {
 113                                 printk(KERN_ERR "scanlog: unknown error from rtas: %d\n", status);
 114                                 return -EIO;
 115                         }
 116                 }
 117                 /* Apparently no data yet.  Wait and try again. */
 118                 msleep_interruptible(wait_time);
 119         }
 120         /*NOTREACHED*/
 121 }
 122
 123 static ssize_t scanlog_write(struct file * file, const char __user * buf,
 124                              size_t count, loff_t *ppos)
 125 {
 126         char stkbuf[20];
 127         int status;
 128
 129         if (count > 19) count = 19;
 130         if (copy_from_user (stkbuf, buf, count)) {
 131                 return -EFAULT;
 132         }
 133         stkbuf[count] = 0;
 134
 135         if (buf) {
 136                 if (strncmp(stkbuf, "reset", 5) == 0) {
 137                         DEBUG("reset scanlog\n");
 138                         status = rtas_call(ibm_scan_log_dump, 2, 1, NULL, 0, 0);
 139                         DEBUG("rtas returns %d\n", status);
 140                 } else if (strncmp(stkbuf, "debugon", 7) == 0) {
 141                         printk(KERN_ERR "scanlog: debug on\n");
 142                         scanlog_debug = 1;
 143                 } else if (strncmp(stkbuf, "debugoff", 8) == 0) {
 144                         printk(KERN_ERR "scanlog: debug off\n");
 145                         scanlog_debug = 0;
 146                 }
 147         }
 148         return count;
 149 }
 150
 151 static int scanlog_open(struct inode * inode, struct file * file)
 152 {
 153         struct proc_dir_entry *dp = PDE(inode);
 154         unsigned int *data = (unsigned int *)dp->data;
 155
 156         if (!data) {
 157                 printk(KERN_ERR "scanlog: open failed no data\n");
 158                 return -EIO;
 159         }
 160
 161         if (data[0] != 0) {
 162                 /* This imperfect test stops a second copy of the
 163                  * data (or a reset while data is being copied)
 164                  */
 165                 return -EBUSY;
 166         }
 167
 168         data[0] = 0;    /* re-init so we restart the scan */
 169
 170         return 0;
 171 }
 172
 173 static int scanlog_release(struct inode * inode, struct file * file)
 174 {
 175         struct proc_dir_entry *dp = PDE(inode);
 176         unsigned int *data = (unsigned int *)dp->data;
 177
 178         if (!data) {
 179                 printk(KERN_ERR "scanlog: release failed no data\n");
 180                 return -EIO;
 181         }
 182         data[0] = 0;
 183
 184         return 0;
 185 }
 186
 187 const struct file_operations scanlog_fops = {
 188         .owner          = THIS_MODULE,
 189         .read           = scanlog_read,
 190         .write          = scanlog_write,
 191         .open           = scanlog_open,
 192         .release        = scanlog_release,
 193 };
 194
 195 static int __init scanlog_init(void)
 196 {
 197         struct proc_dir_entry *ent;
 198
 199         ibm_scan_log_dump = rtas_token("ibm,scan-log-dump");
 200         if (ibm_scan_log_dump == RTAS_UNKNOWN_SERVICE) {
 201                 printk(KERN_ERR "scan-log-dump not implemented on this system\n");
 202                 return -EIO;
 203         }
 204
 205         ent = create_proc_entry("ppc64/rtas/scan-log-dump",  S_IRUSR, NULL);
 206         if (ent) {
 207                 ent->proc_fops = &scanlog_fops;
 208                 /* Ideally we could allocate a buffer < 4G */
 209                 ent->data = kmalloc(RTAS_DATA_BUF_SIZE, GFP_KERNEL);
 210                 if (!ent->data) {
 211                         printk(KERN_ERR "Failed to allocate a buffer\n");
 212                         remove_proc_entry("scan-log-dump", ent->parent);
 213                         return -ENOMEM;
 214                 }
 215                 ((unsigned int *)ent->data)[0] = 0;
 216         } else {
 217                 printk(KERN_ERR "Failed to create ppc64/scan-log-dump proc entry\n");
 218                 return -EIO;
 219         }
 220         proc_ppc64_scan_log_dump = ent;
 221
 222         return 0;
 223 }
 224
 225 static void __exit scanlog_cleanup(void)
 226 {
 227         if (proc_ppc64_scan_log_dump) {
 228                 kfree(proc_ppc64_scan_log_dump->data);
 229                 remove_proc_entry("scan-log-dump", proc_ppc64_scan_log_dump->parent);
 230         }
 231 }
 232
 233 module_init(scanlog_init);
 234 module_exit(scanlog_cleanup);
 235 MODULE_LICENSE("GPL");