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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* c 2001 PPC 64 Team, IBM Corp
*
* scan-log-data driver for PPC64 Todd Inglett <tinglett@vnet.ibm.com>
*
* When ppc64 hardware fails the service processor dumps internal state
* of the system. After a reboot the operating system can access a dump
* of this data using this driver. A dump exists if the device-tree
* /chosen/ibm,scan-log-data property exists.
*
* This driver exports /proc/powerpc/scan-log-dump which can be read.
* The driver supports only sequential reads.
*
* The driver looks at a write to the driver for the single word "reset".
* If given, the driver will reset the scanlog so the platform can free it.
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/proc_fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <asm/rtas.h>
#include <asm/prom.h>
#define MODULE_VERS "1.0"
#define MODULE_NAME "scanlog"
/* Status returns from ibm,scan-log-dump */
#define SCANLOG_COMPLETE 0
#define SCANLOG_HWERROR -1
#define SCANLOG_CONTINUE 1
static unsigned int ibm_scan_log_dump; /* RTAS token */
static unsigned int *scanlog_buffer; /* The data buffer */
static ssize_t scanlog_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
unsigned int *data = scanlog_buffer;
int status;
unsigned long len, off;
unsigned int wait_time;
if (count > RTAS_DATA_BUF_SIZE)
count = RTAS_DATA_BUF_SIZE;
if (count < 1024) {
/* This is the min supported by this RTAS call. Rather
* than do all the buffering we insist the user code handle
* larger reads. As long as cp works... :)
*/
printk(KERN_ERR "scanlog: cannot perform a small read (%ld)\n", count);
return -EINVAL;
}
if (!access_ok(buf, count))
return -EFAULT;
for (;;) {
wait_time = 500; /* default wait if no data */
spin_lock(&rtas_data_buf_lock);
memcpy(rtas_data_buf, data, RTAS_DATA_BUF_SIZE);
status = rtas_call(ibm_scan_log_dump, 2, 1, NULL,
(u32) __pa(rtas_data_buf), (u32) count);
memcpy(data, rtas_data_buf, RTAS_DATA_BUF_SIZE);
spin_unlock(&rtas_data_buf_lock);
pr_debug("scanlog: status=%d, data[0]=%x, data[1]=%x, " \
"data[2]=%x\n", status, data[0], data[1], data[2]);
switch (status) {
case SCANLOG_COMPLETE:
pr_debug("scanlog: hit eof\n");
return 0;
case SCANLOG_HWERROR:
pr_debug("scanlog: hardware error reading data\n");
return -EIO;
case SCANLOG_CONTINUE:
/* We may or may not have data yet */
len = data[1];
off = data[2];
if (len > 0) {
if (copy_to_user(buf, ((char *)data)+off, len))
return -EFAULT;
return len;
}
/* Break to sleep default time */
break;
default:
/* Assume extended busy */
wait_time = rtas_busy_delay_time(status);
if (!wait_time) {
printk(KERN_ERR "scanlog: unknown error " \
"from rtas: %d\n", status);
return -EIO;
}
}
/* Apparently no data yet. Wait and try again. */
msleep_interruptible(wait_time);
}
/*NOTREACHED*/
}
static ssize_t scanlog_write(struct file * file, const char __user * buf,
size_t count, loff_t *ppos)
{
char stkbuf[20];
int status;
if (count > 19) count = 19;
if (copy_from_user (stkbuf, buf, count)) {
return -EFAULT;
}
stkbuf[count] = 0;
if (buf) {
if (strncmp(stkbuf, "reset", 5) == 0) {
pr_debug("scanlog: reset scanlog\n");
status = rtas_call(ibm_scan_log_dump, 2, 1, NULL, 0, 0);
pr_debug("scanlog: rtas returns %d\n", status);
}
}
return count;
}
static int scanlog_open(struct inode * inode, struct file * file)
{
unsigned int *data = scanlog_buffer;
if (data[0] != 0) {
/* This imperfect test stops a second copy of the
* data (or a reset while data is being copied)
*/
return -EBUSY;
}
data[0] = 0; /* re-init so we restart the scan */
return 0;
}
static int scanlog_release(struct inode * inode, struct file * file)
{
unsigned int *data = scanlog_buffer;
data[0] = 0;
return 0;
}
static const struct file_operations scanlog_fops = {
.owner = THIS_MODULE,
.read = scanlog_read,
.write = scanlog_write,
.open = scanlog_open,
.release = scanlog_release,
.llseek = noop_llseek,
};
static int __init scanlog_init(void)
{
struct proc_dir_entry *ent;
int err = -ENOMEM;
ibm_scan_log_dump = rtas_token("ibm,scan-log-dump");
if (ibm_scan_log_dump == RTAS_UNKNOWN_SERVICE)
return -ENODEV;
/* Ideally we could allocate a buffer < 4G */
scanlog_buffer = kzalloc(RTAS_DATA_BUF_SIZE, GFP_KERNEL);
if (!scanlog_buffer)
goto err;
ent = proc_create("powerpc/rtas/scan-log-dump", 0400, NULL,
&scanlog_fops);
if (!ent)
goto err;
return 0;
err:
kfree(scanlog_buffer);
return err;
}
static void __exit scanlog_cleanup(void)
{
remove_proc_entry("powerpc/rtas/scan-log-dump", NULL);
kfree(scanlog_buffer);
}
module_init(scanlog_init);
module_exit(scanlog_cleanup);
MODULE_LICENSE("GPL");
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