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
  42 static unsigned int ibm_scan_log_dump;                  /* RTAS token */
  43 static struct proc_dir_entry *proc_ppc64_scan_log_dump; /* The proc file */
  44
  45 static ssize_t scanlog_read(struct file *file, char __user *buf,
  46                             size_t count, loff_t *ppos)
  47 {
  48         struct inode * inode = file->f_path.dentry->d_inode;
  49         struct proc_dir_entry *dp;
  50         unsigned int *data;
  51         int status;
  52         unsigned long len, off;
  53         unsigned int wait_time;
  54
  55         dp = PDE(inode);
  56         data = (unsigned int *)dp->data;
  57
  58         if (count > RTAS_DATA_BUF_SIZE)
  59                 count = RTAS_DATA_BUF_SIZE;
  60
  61         if (count < 1024) {
  62                 /* This is the min supported by this RTAS call.  Rather
  63                  * than do all the buffering we insist the user code handle
  64                  * larger reads.  As long as cp works... :)
  65                  */
  66                 printk(KERN_ERR "scanlog: cannot perform a small read (%ld)\n", count);
  67                 return -EINVAL;
  68         }
  69
  70         if (!access_ok(VERIFY_WRITE, buf, count))
  71                 return -EFAULT;
  72
  73         for (;;) {
  74                 wait_time = 500;        /* default wait if no data */
  75                 spin_lock(&rtas_data_buf_lock);
  76                 memcpy(rtas_data_buf, data, RTAS_DATA_BUF_SIZE);
  77                 status = rtas_call(ibm_scan_log_dump, 2, 1, NULL,
  78                                    (u32) __pa(rtas_data_buf), (u32) count);
  79                 memcpy(data, rtas_data_buf, RTAS_DATA_BUF_SIZE);
  80                 spin_unlock(&rtas_data_buf_lock);
  81
  82                 pr_debug("scanlog: status=%d, data[0]=%x, data[1]=%x, " \
  83                          "data[2]=%x\n", status, data[0], data[1], data[2]);
  84                 switch (status) {
  85                     case SCANLOG_COMPLETE:
  86                         pr_debug("scanlog: hit eof\n");
  87                         return 0;
  88                     case SCANLOG_HWERROR:
  89                         pr_debug("scanlog: hardware error reading data\n");
  90                         return -EIO;
  91                     case SCANLOG_CONTINUE:
  92                         /* We may or may not have data yet */
  93                         len = data[1];
  94                         off = data[2];
  95                         if (len > 0) {
  96                                 if (copy_to_user(buf, ((char *)data)+off, len))
  97                                         return -EFAULT;
  98                                 return len;
  99                         }
 100                         /* Break to sleep default time */
 101                         break;
 102                     default:
 103                         /* Assume extended busy */
 104                         wait_time = rtas_busy_delay_time(status);
 105                         if (!wait_time) {
 106                                 printk(KERN_ERR "scanlog: unknown error " \
 107                                        "from rtas: %d\n", status);
 108                                 return -EIO;
 109                         }
 110                 }
 111                 /* Apparently no data yet.  Wait and try again. */
 112                 msleep_interruptible(wait_time);
 113         }
 114         /*NOTREACHED*/
 115 }
 116
 117 static ssize_t scanlog_write(struct file * file, const char __user * buf,
 118                              size_t count, loff_t *ppos)
 119 {
 120         char stkbuf[20];
 121         int status;
 122
 123         if (count > 19) count = 19;
 124         if (copy_from_user (stkbuf, buf, count)) {
 125                 return -EFAULT;
 126         }
 127         stkbuf[count] = 0;
 128
 129         if (buf) {
 130                 if (strncmp(stkbuf, "reset", 5) == 0) {
 131                         pr_debug("scanlog: reset scanlog\n");
 132                         status = rtas_call(ibm_scan_log_dump, 2, 1, NULL, 0, 0);
 133                         pr_debug("scanlog: rtas returns %d\n", status);
 134                 }
 135         }
 136         return count;
 137 }
 138
 139 static int scanlog_open(struct inode * inode, struct file * file)
 140 {
 141         struct proc_dir_entry *dp = PDE(inode);
 142         unsigned int *data = (unsigned int *)dp->data;
 143
 144         if (data[0] != 0) {
 145                 /* This imperfect test stops a second copy of the
 146                  * data (or a reset while data is being copied)
 147                  */
 148                 return -EBUSY;
 149         }
 150
 151         data[0] = 0;    /* re-init so we restart the scan */
 152
 153         return 0;
 154 }
 155
 156 static int scanlog_release(struct inode * inode, struct file * file)
 157 {
 158         struct proc_dir_entry *dp = PDE(inode);
 159         unsigned int *data = (unsigned int *)dp->data;
 160
 161         data[0] = 0;
 162
 163         return 0;
 164 }
 165
 166 const struct file_operations scanlog_fops = {
 167         .owner          = THIS_MODULE,
 168         .read           = scanlog_read,
 169         .write          = scanlog_write,
 170         .open           = scanlog_open,
 171         .release        = scanlog_release,
 172 };
 173
 174 static int __init scanlog_init(void)
 175 {
 176         struct proc_dir_entry *ent;
 177         void *data;
 178         int err = -ENOMEM;
 179
 180         ibm_scan_log_dump = rtas_token("ibm,scan-log-dump");
 181         if (ibm_scan_log_dump == RTAS_UNKNOWN_SERVICE)
 182                 return -ENODEV;
 183
 184         /* Ideally we could allocate a buffer < 4G */
 185         data = kzalloc(RTAS_DATA_BUF_SIZE, GFP_KERNEL);
 186         if (!data)
 187                 goto err;
 188
 189         ent = proc_create_data("ppc64/rtas/scan-log-dump", S_IRUSR, NULL,
 190                                &scanlog_fops, data);
 191         if (!ent)
 192                 goto err;
 193
 194         proc_ppc64_scan_log_dump = ent;
 195
 196         return 0;
 197 err:
 198         kfree(data);
 199         return err;
 200 }
 201
 202 static void __exit scanlog_cleanup(void)
 203 {
 204         if (proc_ppc64_scan_log_dump) {
 205                 kfree(proc_ppc64_scan_log_dump->data);
 206                 remove_proc_entry("scan-log-dump", proc_ppc64_scan_log_dump->parent);
 207         }
 208 }
 209
 210 module_init(scanlog_init);
 211 module_exit(scanlog_cleanup);
 212 MODULE_LICENSE("GPL");