LXR linux/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
  43static unsigned int ibm_scan_log_dump;                  /* RTAS token */
  44static struct proc_dir_entry *proc_ppc64_scan_log_dump; /* The proc file */
  45
  46static 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
 118static 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
 140static 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
 157static 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
 167const 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        .llseek         = noop_llseek,
 174};
 175
 176static int __init scanlog_init(void)
 177{
 178        struct proc_dir_entry *ent;
 179        void *data;
 180        int err = -ENOMEM;
 181
 182        ibm_scan_log_dump = rtas_token("ibm,scan-log-dump");
 183        if (ibm_scan_log_dump == RTAS_UNKNOWN_SERVICE)
 184                return -ENODEV;
 185
 186        /* Ideally we could allocate a buffer < 4G */
 187        data = kzalloc(RTAS_DATA_BUF_SIZE, GFP_KERNEL);
 188        if (!data)
 189                goto err;
 190
 191        ent = proc_create_data("powerpc/rtas/scan-log-dump", S_IRUSR, NULL,
 192                               &scanlog_fops, data);
 193        if (!ent)
 194                goto err;
 195
 196        proc_ppc64_scan_log_dump = ent;
 197
 198        return 0;
 199err:
 200        kfree(data);
 201        return err;
 202}
 203
 204static void __exit scanlog_cleanup(void)
 205{
 206        if (proc_ppc64_scan_log_dump) {
 207                kfree(proc_ppc64_scan_log_dump->data);
 208                remove_proc_entry("scan-log-dump", proc_ppc64_scan_log_dump->parent);
 209        }
 210}
 211
 212module_init(scanlog_init);
 213module_exit(scanlog_cleanup);
 214MODULE_LICENSE("GPL");
 215