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TOMOYO Linux Cross Reference
Linux/arch/powerpc/platforms/pseries/scanlog.c

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  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 <linux/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 static 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", 0400, 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");
201 

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