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/powerpc/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 <linux/slab.h>
  30 #include <asm/uaccess.h>
  31 #include <asm/rtas.h>
  32 #include <asm/prom.h>
  33
  34 #define MODULE_VERS "1.0"
  35 #define MODULE_NAME "scanlog"
  36
  37 /* Status returns from ibm,scan-log-dump */
  38 #define SCANLOG_COMPLETE 0
  39 #define SCANLOG_HWERROR -1
  40 #define SCANLOG_CONTINUE 1
  41
  42
  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 __user *buf,
  47                             size_t count, loff_t *ppos)
  48 {
  49         struct inode * inode = file->f_path.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 (count > RTAS_DATA_BUF_SIZE)
  60                 count = RTAS_DATA_BUF_SIZE;
  61
  62         if (count < 1024) {
  63                 /* This is the min supported by this RTAS call.  Rather
  64                  * than do all the buffering we insist the user code handle
  65                  * larger reads.  As long as cp works... :)
  66                  */
  67                 printk(KERN_ERR "scanlog: cannot perform a small read (%ld)\n", count);
  68                 return -EINVAL;
  69         }
  70
  71         if (!access_ok(VERIFY_WRITE, buf, count))
  72                 return -EFAULT;
  73
  74         for (;;) {
  75                 wait_time = 500;        /* default wait if no data */
  76                 spin_lock(&rtas_data_buf_lock);
  77                 memcpy(rtas_data_buf, data, RTAS_DATA_BUF_SIZE);
  78                 status = rtas_call(ibm_scan_log_dump, 2, 1, NULL,
  79                                    (u32) __pa(rtas_data_buf), (u32) count);
  80                 memcpy(data, rtas_data_buf, RTAS_DATA_BUF_SIZE);
  81                 spin_unlock(&rtas_data_buf_lock);
  82
  83                 pr_debug("scanlog: status=%d, data[0]=%x, data[1]=%x, " \
  84                          "data[2]=%x\n", status, data[0], data[1], data[2]);
  85                 switch (status) {
  86                     case SCANLOG_COMPLETE:
  87                         pr_debug("scanlog: hit eof\n");
  88                         return 0;
  89                     case SCANLOG_HWERROR:
  90                         pr_debug("scanlog: hardware error reading data\n");
  91                         return -EIO;
  92                     case SCANLOG_CONTINUE:
  93                         /* We may or may not have data yet */
  94                         len = data[1];
  95                         off = data[2];
  96                         if (len > 0) {
  97                                 if (copy_to_user(buf, ((char *)data)+off, len))
  98                                         return -EFAULT;
  99                                 return len;
 100                         }
 101                         /* Break to sleep default time */
 102                         break;
 103                     default:
 104                         /* Assume extended busy */
 105                         wait_time = rtas_busy_delay_time(status);
 106                         if (!wait_time) {
 107                                 printk(KERN_ERR "scanlog: unknown error " \
 108                                        "from rtas: %d\n", status);
 109                                 return -EIO;
 110                         }
 111                 }
 112                 /* Apparently no data yet.  Wait and try again. */
 113                 msleep_interruptible(wait_time);
 114         }
 115         /*NOTREACHED*/
 116 }
 117
 118 static ssize_t scanlog_write(struct file * file, const char __user * buf,
 119                              size_t count, loff_t *ppos)
 120 {
 121         char stkbuf[20];
 122         int status;
 123
 124         if (count > 19) count = 19;
 125         if (copy_from_user (stkbuf, buf, count)) {
 126                 return -EFAULT;
 127         }
 128         stkbuf[count] = 0;
 129
 130         if (buf) {
 131                 if (strncmp(stkbuf, "reset", 5) == 0) {
 132                         pr_debug("scanlog: reset scanlog\n");
 133                         status = rtas_call(ibm_scan_log_dump, 2, 1, NULL, 0, 0);
 134                         pr_debug("scanlog: rtas returns %d\n", status);
 135                 }
 136         }
 137         return count;
 138 }
 139
 140 static int scanlog_open(struct inode * inode, struct file * file)
 141 {
 142         struct proc_dir_entry *dp = PDE(inode);
 143         unsigned int *data = (unsigned int *)dp->data;
 144
 145         if (data[0] != 0) {
 146                 /* This imperfect test stops a second copy of the
 147                  * data (or a reset while data is being copied)
 148                  */
 149                 return -EBUSY;
 150         }
 151
 152         data[0] = 0;    /* re-init so we restart the scan */
 153
 154         return 0;
 155 }
 156
 157 static int scanlog_release(struct inode * inode, struct file * file)
 158 {
 159         struct proc_dir_entry *dp = PDE(inode);
 160         unsigned int *data = (unsigned int *)dp->data;
 161
 162         data[0] = 0;
 163
 164         return 0;
 165 }
 166
 167 const struct file_operations scanlog_fops = {
 168         .owner          = THIS_MODULE,
 169         .read           = scanlog_read,
 170         .write          = scanlog_write,
 171         .open           = scanlog_open,
 172         .release        = scanlog_release,
 173 };
 174
 175 static int __init scanlog_init(void)
 176 {
 177         struct proc_dir_entry *ent;
 178         void *data;
 179         int err = -ENOMEM;
 180
 181         ibm_scan_log_dump = rtas_token("ibm,scan-log-dump");
 182         if (ibm_scan_log_dump == RTAS_UNKNOWN_SERVICE)
 183                 return -ENODEV;
 184
 185         /* Ideally we could allocate a buffer < 4G */
 186         data = kzalloc(RTAS_DATA_BUF_SIZE, GFP_KERNEL);
 187         if (!data)
 188                 goto err;
 189
 190         ent = proc_create_data("powerpc/rtas/scan-log-dump", S_IRUSR, NULL,
 191                                &scanlog_fops, data);
 192         if (!ent)
 193                 goto err;
 194
 195         proc_ppc64_scan_log_dump = ent;
 196
 197         return 0;
 198 err:
 199         kfree(data);
 200         return err;
 201 }
 202
 203 static void __exit scanlog_cleanup(void)
 204 {
 205         if (proc_ppc64_scan_log_dump) {
 206                 kfree(proc_ppc64_scan_log_dump->data);
 207                 remove_proc_entry("scan-log-dump", proc_ppc64_scan_log_dump->parent);
 208         }
 209 }
 210
 211 module_init(scanlog_init);
 212 module_exit(scanlog_cleanup);
 213 MODULE_LICENSE("GPL");