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