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