arch/ppc64/kernel/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 <asm/uaccess.h>
  29 #include <asm/rtas.h>
  30 #include <asm/prom.h>
  31
  32 #define MODULE_VERS "1.0"
  33 #define MODULE_NAME "scanlog"
  34
  35 /* Status returns from ibm,scan-log-dump */
  36 #define SCANLOG_COMPLETE 0
  37 #define SCANLOG_HWERROR -1
  38 #define SCANLOG_CONTINUE 1
  39
  40 #define DEBUG(A...) do { if (scanlog_debug) printk(KERN_ERR "scanlog: " A); } while (0)
  41
  42 static int scanlog_debug;
  43 static unsigned int ibm_scan_log_dump;                  /* RTAS token */
  44 static struct proc_dir_entry *proc_ppc64_scan_log_dump; /* The proc file */
  45
  46 static ssize_t scanlog_read(struct file *file, char *buf,
  47                             size_t count, loff_t *ppos)
  48 {
  49         struct inode * inode = file->f_dentry->d_inode;
  50         struct proc_dir_entry *dp;
  51         unsigned int *data;
  52         int status;
  53         unsigned long len, off;
  54         unsigned int wait_time;
  55
  56         dp = PDE(inode);
  57         data = (unsigned int *)dp->data;
  58
  59         if (!data) {
  60                 printk(KERN_ERR "scanlog: read failed no data\n");
  61                 return -EIO;
  62         }
  63
  64         if (count > RTAS_DATA_BUF_SIZE)
  65                 count = RTAS_DATA_BUF_SIZE;
  66
  67         if (count < 1024) {
  68                 /* This is the min supported by this RTAS call.  Rather
  69                  * than do all the buffering we insist the user code handle
  70                  * larger reads.  As long as cp works... :)
  71                  */
  72                 printk(KERN_ERR "scanlog: cannot perform a small read (%ld)\n", count);
  73                 return -EINVAL;
  74         }
  75
  76         if (!access_ok(VERIFY_WRITE, buf, count))
  77                 return -EFAULT;
  78
  79         for (;;) {
  80                 wait_time = HZ/2;       /* default wait if no data */
  81                 spin_lock(&rtas_data_buf_lock);
  82                 memcpy(rtas_data_buf, data, RTAS_DATA_BUF_SIZE);
  83                 status = rtas_call(ibm_scan_log_dump, 2, 1, NULL,
  84                                    (u32) __pa(rtas_data_buf), (u32) count);
  85                 memcpy(data, rtas_data_buf, RTAS_DATA_BUF_SIZE);
  86                 spin_unlock(&rtas_data_buf_lock);
  87
  88                 DEBUG("status=%d, data[0]=%x, data[1]=%x, data[2]=%x\n",
  89                       status, data[0], data[1], data[2]);
  90                 switch (status) {
  91                     case SCANLOG_COMPLETE:
  92                         DEBUG("hit eof\n");
  93                         return 0;
  94                     case SCANLOG_HWERROR:
  95                         DEBUG("hardware error reading scan log data\n");
  96                         return -EIO;
  97                     case SCANLOG_CONTINUE:
  98                         /* We may or may not have data yet */
  99                         len = data[1];
 100                         off = data[2];
 101                         if (len > 0) {
 102                                 if (copy_to_user(buf, ((char *)data)+off, len))
 103                                         return -EFAULT;
 104                                 return len;
 105                         }
 106                         /* Break to sleep default time */
 107                         break;
 108                     default:
 109                         if (status > 9900 && status <= 9905) {
 110                                 /* No data.  RTAS is hinting at a delay required
 111                                  * between 1-100000 milliseconds
 112                                  */
 113                                 int ms = 1;
 114                                 for (; status > 9900; status--)
 115                                         ms = ms * 10;
 116                                 /* Use microseconds for reasonable accuracy */
 117                                 ms *= 1000;
 118                                 wait_time = ms / (1000000/HZ); /* round down is fine */
 119                                 /* Fall through to sleep */
 120                         } else {
 121                                 printk(KERN_ERR "scanlog: unknown error from rtas: %d\n", status);
 122                                 return -EIO;
 123                         }
 124                 }
 125                 /* Apparently no data yet.  Wait and try again. */
 126                 set_current_state(TASK_INTERRUPTIBLE);
 127                 schedule_timeout(wait_time);
 128         }
 129         /*NOTREACHED*/
 130 }
 131
 132 static ssize_t scanlog_write(struct file * file, const char * buf,
 133                              size_t count, loff_t *ppos)
 134 {
 135         char stkbuf[20];
 136         int status;
 137
 138         if (count > 19) count = 19;
 139         if (copy_from_user (stkbuf, buf, count)) {
 140                 return -EFAULT;
 141         }
 142         stkbuf[count] = 0;
 143
 144         if (buf) {
 145                 if (strncmp(stkbuf, "reset", 5) == 0) {
 146                         DEBUG("reset scanlog\n");
 147                         status = rtas_call(ibm_scan_log_dump, 2, 1, NULL, 0, 0);
 148                         DEBUG("rtas returns %d\n", status);
 149                 } else if (strncmp(stkbuf, "debugon", 7) == 0) {
 150                         printk(KERN_ERR "scanlog: debug on\n");
 151                         scanlog_debug = 1;
 152                 } else if (strncmp(stkbuf, "debugoff", 8) == 0) {
 153                         printk(KERN_ERR "scanlog: debug off\n");
 154                         scanlog_debug = 0;
 155                 }
 156         }
 157         return count;
 158 }
 159
 160 static int scanlog_open(struct inode * inode, struct file * file)
 161 {
 162         struct proc_dir_entry *dp = PDE(inode);
 163         unsigned int *data = (unsigned int *)dp->data;
 164
 165         if (!data) {
 166                 printk(KERN_ERR "scanlog: open failed no data\n");
 167                 return -EIO;
 168         }
 169
 170         if (data[0] != 0) {
 171                 /* This imperfect test stops a second copy of the
 172                  * data (or a reset while data is being copied)
 173                  */
 174                 return -EBUSY;
 175         }
 176
 177         data[0] = 0;    /* re-init so we restart the scan */
 178
 179         return 0;
 180 }
 181
 182 static int scanlog_release(struct inode * inode, struct file * file)
 183 {
 184         struct proc_dir_entry *dp = PDE(inode);
 185         unsigned int *data = (unsigned int *)dp->data;
 186
 187         if (!data) {
 188                 printk(KERN_ERR "scanlog: release failed no data\n");
 189                 return -EIO;
 190         }
 191         data[0] = 0;
 192
 193         return 0;
 194 }
 195
 196 struct file_operations scanlog_fops = {
 197         .owner          = THIS_MODULE,
 198         .read           = scanlog_read,
 199         .write          = scanlog_write,
 200         .open           = scanlog_open,
 201         .release        = scanlog_release,
 202 };
 203
 204 int __init scanlog_init(void)
 205 {
 206         struct proc_dir_entry *ent;
 207
 208         ibm_scan_log_dump = rtas_token("ibm,scan-log-dump");
 209         if (ibm_scan_log_dump == RTAS_UNKNOWN_SERVICE) {
 210                 printk(KERN_ERR "scan-log-dump not implemented on this system\n");
 211                 return -EIO;
 212         }
 213
 214         ent = create_proc_entry("ppc64/rtas/scan-log-dump",  S_IRUSR, NULL);
 215         if (ent) {
 216                 ent->proc_fops = &scanlog_fops;
 217                 /* Ideally we could allocate a buffer < 4G */
 218                 ent->data = kmalloc(RTAS_DATA_BUF_SIZE, GFP_KERNEL);
 219                 if (!ent->data) {
 220                         printk(KERN_ERR "Failed to allocate a buffer\n");
 221                         remove_proc_entry("scan-log-dump", ent->parent);
 222                         return -ENOMEM;
 223                 }
 224                 ((unsigned int *)ent->data)[0] = 0;
 225         } else {
 226                 printk(KERN_ERR "Failed to create ppc64/scan-log-dump proc entry\n");
 227                 return -EIO;
 228         }
 229         proc_ppc64_scan_log_dump = ent;
 230
 231         return 0;
 232 }
 233
 234 void __exit scanlog_cleanup(void)
 235 {
 236         if (proc_ppc64_scan_log_dump) {
 237                 if (proc_ppc64_scan_log_dump->data)
 238                         kfree(proc_ppc64_scan_log_dump->data);
 239                 remove_proc_entry("scan-log-dump", proc_ppc64_scan_log_dump->parent);
 240         }
 241 }
 242
 243 module_init(scanlog_init);
 244 module_exit(scanlog_cleanup);
 245 MODULE_LICENSE("GPL");