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/*

 *  c 2001 PPC 64 Team, IBM Corp

 *

 *      This program is free software; you can redistribute it and/or

 *      modify it under the terms of the GNU General Public License

 *      as published by the Free Software Foundation; either version

 *      2 of the License, or (at your option) any later version.

 *

 * 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/ppc64/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 <asm/uaccess.h>

#include <asm/rtas.h>

#include <asm/prom.h>

#define MODULE_VERSION "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

#define DEBUG(A...) do { if (scanlog_debug) printk(KERN_ERR "scanlog: " A); } while (0)

static int scanlog_debug;

static unsigned int ibm_scan_log_dump;                  /* RTAS token */

static struct proc_dir_entry *proc_ppc64_scan_log_dump; /* The proc file */

static ssize_t scanlog_read(struct file *file, char *buf,

                            size_t count, loff_t *ppos)

{

        struct proc_dir_entry *dp = file->f_dentry->d_inode->u.generic_ip;

        unsigned int *data = (unsigned int *)dp->data;

        unsigned long status;

        unsigned long len, off;

        unsigned int wait_time;

        if (!data) {

                printk(KERN_ERR "scanlog: read failed no data\n");

                return -EIO;

        }

        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 (verify_area(VERIFY_WRITE, buf, count))

                return -EFAULT;

        for (;;) {

                wait_time = HZ/2;       /* 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,

                                   __pa(rtas_data_buf), count);

                memcpy(data, rtas_data_buf, RTAS_DATA_BUF_SIZE);

                spin_unlock(&rtas_data_buf_lock);

                DEBUG("status=%ld, data[0]=%x, data[1]=%x, data[2]=%x\n",

                      status, data[0], data[1], data[2]);

                switch (status) {

                    case SCANLOG_COMPLETE:

                        DEBUG("hit eof\n");

                        return 0;

                    case SCANLOG_HWERROR:

                        DEBUG("hardware error reading scan log 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:

                        if (status > 9900 && status <= 9905) {

                                /* No data.  RTAS is hinting at a delay required

                                 * between 1-100000 milliseconds

                                 */

                                int ms = 1;

                                for (; status > 9900; status--)

                                        ms = ms * 10;

                                /* Use microseconds for reasonable accuracy */

                                ms *= 1000;

                                wait_time = ms / (1000000/HZ); /* round down is fine */

                                /* Fall through to sleep */

                        } else {

                                printk(KERN_ERR "scanlog: unknown error from rtas: %ld\n", status);

                                return -EIO;

                        }

                }

                /* Apparently no data yet.  Wait and try again. */

                set_current_state(TASK_INTERRUPTIBLE);

                schedule_timeout(wait_time);

        }

        /*NOTREACHED*/

}

static ssize_t scanlog_write(struct file * file, const char * buf,

                             size_t count, loff_t *ppos)

{

        char stkbuf[20];

        unsigned long 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) {

                        DEBUG("reset scanlog\n");

                        status = rtas_call(ibm_scan_log_dump, 2, 1, NULL, NULL, 0);

                        DEBUG("rtas returns %ld\n", status);

                } else if (strncmp(stkbuf, "debugon", 7) == 0) {

                        printk(KERN_ERR "scanlog: debug on\n");

                        scanlog_debug = 1;

                } else if (strncmp(stkbuf, "debugoff", 8) == 0) {

                        printk(KERN_ERR "scanlog: debug off\n");

                        scanlog_debug = 0;

                }

        }

        return count;

}

static int scanlog_open(struct inode * inode, struct file * file)

{

        struct proc_dir_entry *dp = file->f_dentry->d_inode->u.generic_ip;

        unsigned int *data = (unsigned int *)dp->data;

        if (!data) {

                printk(KERN_ERR "scanlog: open failed no data\n");

                return -EIO;

        }

        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)

{

        struct proc_dir_entry *dp = file->f_dentry->d_inode->u.generic_ip;

        unsigned int *data = (unsigned int *)dp->data;

        if (!data) {

                printk(KERN_ERR "scanlog: release failed no data\n");

                return -EIO;

        }

        data[0] = 0;

        return 0;

}

struct file_operations scanlog_fops = {

        owner:          THIS_MODULE,

        read:           scanlog_read,

        write:          scanlog_write,

        open:           scanlog_open,

        release:        scanlog_release,

};

int __init scanlog_init(void)

{

        struct proc_dir_entry *ent;

        ibm_scan_log_dump = rtas_token("ibm,scan-log-dump");

        if (ibm_scan_log_dump == RTAS_UNKNOWN_SERVICE) {

                printk(KERN_ERR "scan-log-dump not implemented on this system\n");

                return -EIO;

        }

        ent = create_proc_entry("ppc64/scan-log-dump", S_IRUSR, NULL);

        if (ent) {

                ent->proc_fops = &scanlog_fops;

                /* Ideally we could allocate a buffer < 4G */

                ent->data = kmalloc(RTAS_DATA_BUF_SIZE, GFP_KERNEL);

                if (!ent->data) {

                        printk(KERN_ERR "Failed to allocate a buffer\n");

                        remove_proc_entry("scan-log-dump", ent->parent);

                        return -ENOMEM;

                }

                ((unsigned int *)ent->data)[0] = 0;

        } else {

                printk(KERN_ERR "Failed to create ppc64/scan-log-dump proc entry\n");

                return -EIO;

        }

        proc_ppc64_scan_log_dump = ent;

        return 0;

}

void __exit scanlog_cleanup(void)

{

        if (proc_ppc64_scan_log_dump) {

                if (proc_ppc64_scan_log_dump->data)

                    kfree(proc_ppc64_scan_log_dump->data);

                remove_proc_entry("scan-log-dump", proc_ppc64_scan_log_dump->parent);

        }

}

module_init(scanlog_init);

module_exit(scanlog_cleanup);

MODULE_LICENSE("GPL");