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/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
  42static unsigned int ibm_scan_log_dump;                  /* RTAS token */
  43static struct proc_dir_entry *proc_ppc64_scan_log_dump; /* The proc file */
  44
  45static 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
 117static 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
 139static 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
 156static 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
 166const 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
 174static 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;
 197err:
 198        kfree(data);
 199        return err;
 200}
 201
 202static 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
 210module_init(scanlog_init);
 211module_exit(scanlog_cleanup);
 212MODULE_LICENSE("GPL");
 213