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 unsigned int *scanlog_buffer;                    /* The data buffer */
  45
  46static 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
 113static 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
 135static 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
 151static 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
 159const 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
 168static 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;
 187err:
 188        kfree(scanlog_buffer);
 189        return err;
 190}
 191
 192static void __exit scanlog_cleanup(void)
 193{
 194        remove_proc_entry("powerpc/rtas/scan-log-dump", NULL);
 195        kfree(scanlog_buffer);
 196}
 197
 198module_init(scanlog_init);
 199module_exit(scanlog_cleanup);
 200MODULE_LICENSE("GPL");
 201