// SPDX-License-Identifier: GPL-2.0
/*
 * linux/drivers/scsi/scsi_proc.c
 *
 * The functions in this file provide an interface between
 * the PROC file system and the SCSI device drivers
 * It is mainly used for debugging, statistics and to pass 
 * information directly to the lowlevel driver.
 *
 * (c) 1995 Michael Neuffer neuffer@goofy.zdv.uni-mainz.de 
 * Version: 0.99.8   last change: 95/09/13
 * 
 * generic command parser provided by: 
 * Andreas Heilwagen <crashcar@informatik.uni-koblenz.de>
 *
 * generic_proc_info() support of xxxx_info() by:
 * Michael A. Griffith <grif@acm.org>
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/proc_fs.h>
#include <linux/errno.h>
#include <linux/blkdev.h>
#include <linux/seq_file.h>
#include <linux/mutex.h>
#include <linux/gfp.h>
#include <linux/uaccess.h>

#include <scsi/scsi.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_transport.h>

#include "scsi_priv.h"
#include "scsi_logging.h"


/* 4K page size, but our output routines, use some slack for overruns */
#define PROC_BLOCK_SIZE (3*1024)

static struct proc_dir_entry *proc_scsi;

/* Protects scsi_proc_list */
static DEFINE_MUTEX(global_host_template_mutex);
static LIST_HEAD(scsi_proc_list);

/**
 * struct scsi_proc_entry - (host template, SCSI proc dir) association
 * @entry: entry in scsi_proc_list.
 * @sht: SCSI host template associated with the procfs directory.
 * @proc_dir: procfs directory associated with the SCSI host template.
 * @present: Number of SCSI hosts instantiated for @sht.
 */
struct scsi_proc_entry {
        struct list_head        entry;
        const struct scsi_host_template *sht;
        struct proc_dir_entry   *proc_dir;
        unsigned int            present;
};

static ssize_t proc_scsi_host_write(struct file *file, const char __user *buf,
                           size_t count, loff_t *ppos)
{
        struct Scsi_Host *shost = pde_data(file_inode(file));
        ssize_t ret = -ENOMEM;
        char *page;
    
        if (count > PROC_BLOCK_SIZE)
                return -EOVERFLOW;

        if (!shost->hostt->write_info)
                return -EINVAL;

        page = (char *)__get_free_page(GFP_KERNEL);
        if (page) {
                ret = -EFAULT;
                if (copy_from_user(page, buf, count))
                        goto out;
                ret = shost->hostt->write_info(shost, page, count);
        }
out:
        free_page((unsigned long)page);
        return ret;
}

static int proc_scsi_show(struct seq_file *m, void *v)
{
        struct Scsi_Host *shost = m->private;
        return shost->hostt->show_info(m, shost);
}

static int proc_scsi_host_open(struct inode *inode, struct file *file)
{
        return single_open_size(file, proc_scsi_show, pde_data(inode),
                                4 * PAGE_SIZE);
}

static struct scsi_proc_entry *
__scsi_lookup_proc_entry(const struct scsi_host_template *sht)
{
        struct scsi_proc_entry *e;

        lockdep_assert_held(&global_host_template_mutex);

        list_for_each_entry(e, &scsi_proc_list, entry)
                if (e->sht == sht)
                        return e;

        return NULL;
}

static struct scsi_proc_entry *
scsi_lookup_proc_entry(const struct scsi_host_template *sht)
{
        struct scsi_proc_entry *e;

        mutex_lock(&global_host_template_mutex);
        e = __scsi_lookup_proc_entry(sht);
        mutex_unlock(&global_host_template_mutex);

        return e;
}

/**
 * scsi_template_proc_dir() - returns the procfs dir for a SCSI host template
 * @sht: SCSI host template pointer.
 */
struct proc_dir_entry *
scsi_template_proc_dir(const struct scsi_host_template *sht)
{
        struct scsi_proc_entry *e = scsi_lookup_proc_entry(sht);

        return e ? e->proc_dir : NULL;
}
EXPORT_SYMBOL_GPL(scsi_template_proc_dir);

static const struct proc_ops proc_scsi_ops = {
        .proc_open      = proc_scsi_host_open,
        .proc_release   = single_release,
        .proc_read      = seq_read,
        .proc_lseek     = seq_lseek,
        .proc_write     = proc_scsi_host_write
};

/**
 * scsi_proc_hostdir_add - Create directory in /proc for a scsi host
 * @sht: owner of this directory
 *
 * Sets sht->proc_dir to the new directory.
 */
int scsi_proc_hostdir_add(const struct scsi_host_template *sht)
{
        struct scsi_proc_entry *e;
        int ret;

        if (!sht->show_info)
                return 0;

        mutex_lock(&global_host_template_mutex);
        e = __scsi_lookup_proc_entry(sht);
        if (!e) {
                e = kzalloc_obj(*e);
                if (!e) {
                        ret = -ENOMEM;
                        goto unlock;
                }
        }
        if (e->present++)
                goto success;
        e->proc_dir = proc_mkdir(sht->proc_name, proc_scsi);
        if (!e->proc_dir) {
                printk(KERN_ERR "%s: proc_mkdir failed for %s\n", __func__,
                       sht->proc_name);
                ret = -ENOMEM;
                goto unlock;
        }
        e->sht = sht;
        list_add_tail(&e->entry, &scsi_proc_list);
success:
        e = NULL;
        ret = 0;
unlock:
        mutex_unlock(&global_host_template_mutex);

        kfree(e);
        return ret;
}

/**
 * scsi_proc_hostdir_rm - remove directory in /proc for a scsi host
 * @sht: owner of directory
 */
void scsi_proc_hostdir_rm(const struct scsi_host_template *sht)
{
        struct scsi_proc_entry *e;

        if (!sht->show_info)
                return;

        mutex_lock(&global_host_template_mutex);
        e = __scsi_lookup_proc_entry(sht);
        if (e && !--e->present) {
                remove_proc_entry(sht->proc_name, proc_scsi);
                list_del(&e->entry);
                kfree(e);
        }
        mutex_unlock(&global_host_template_mutex);
}


/**
 * scsi_proc_host_add - Add entry for this host to appropriate /proc dir
 * @shost: host to add
 */
void scsi_proc_host_add(struct Scsi_Host *shost)
{
        const struct scsi_host_template *sht = shost->hostt;
        struct scsi_proc_entry *e;
        struct proc_dir_entry *p;
        char name[10];

        if (!sht->show_info)
                return;

        e = scsi_lookup_proc_entry(sht);
        if (!e)
                goto err;

        sprintf(name,"%d", shost->host_no);
        p = proc_create_data(name, S_IRUGO | S_IWUSR, e->proc_dir,
                             &proc_scsi_ops, shost);
        if (!p)
                goto err;
        return;

err:
        shost_printk(KERN_ERR, shost,
                     "%s: Failed to register host (%s failed)\n", __func__,
                     e ? "proc_create_data()" : "scsi_proc_hostdir_add()");
}

/**
 * scsi_proc_host_rm - remove this host's entry from /proc
 * @shost: which host
 */
void scsi_proc_host_rm(struct Scsi_Host *shost)
{
        const struct scsi_host_template *sht = shost->hostt;
        struct scsi_proc_entry *e;
        char name[10];

        if (!sht->show_info)
                return;

        e = scsi_lookup_proc_entry(sht);
        if (!e)
                return;

        sprintf(name,"%d", shost->host_no);
        remove_proc_entry(name, e->proc_dir);
}
/**
 * proc_print_scsidevice - return data about this host
 * @dev: A scsi device
 * @data: &struct seq_file to output to.
 *
 * Description: prints Host, Channel, Id, Lun, Vendor, Model, Rev, Type,
 * and revision.
 */
static int proc_print_scsidevice(struct device *dev, void *data)
{
        struct scsi_device *sdev;
        struct seq_file *s = data;
        int i;

        if (!scsi_is_sdev_device(dev))
                goto out;

        sdev = to_scsi_device(dev);
        seq_printf(s,
                "Host: scsi%d Channel: %02d Id: %02d Lun: %02llu\n  Vendor: ",
                sdev->host->host_no, sdev->channel, sdev->id, sdev->lun);
        for (i = 0; i < 8; i++) {
                if (sdev->vendor[i] >= 0x20)
                        seq_putc(s, sdev->vendor[i]);
                else
                        seq_putc(s, ' ');
        }

        seq_puts(s, " Model: ");
        for (i = 0; i < 16; i++) {
                if (sdev->model[i] >= 0x20)
                        seq_putc(s, sdev->model[i]);
                else
                        seq_putc(s, ' ');
        }

        seq_puts(s, " Rev: ");
        for (i = 0; i < 4; i++) {
                if (sdev->rev[i] >= 0x20)
                        seq_putc(s, sdev->rev[i]);
                else
                        seq_putc(s, ' ');
        }

        seq_putc(s, '\n');

        seq_printf(s, "  Type:   %s ", scsi_device_type(sdev->type));
        seq_printf(s, "               ANSI  SCSI revision: %02x",
                        sdev->scsi_level - (sdev->scsi_level > 1));
        if (sdev->scsi_level == 2)
                seq_puts(s, " CCS\n");
        else
                seq_putc(s, '\n');

out:
        return 0;
}

/**
 * scsi_add_single_device - Respond to user request to probe for/add device
 * @host: user-supplied decimal integer
 * @channel: user-supplied decimal integer
 * @id: user-supplied decimal integer
 * @lun: user-supplied decimal integer
 *
 * Description: called by writing "scsi add-single-device" to /proc/scsi/scsi.
 *
 * does scsi_host_lookup() and either user_scan() if that transport
 * type supports it, or else scsi_scan_host_selected()
 *
 * Note: this seems to be aimed exclusively at SCSI parallel busses.
 */

static int scsi_add_single_device(uint host, uint channel, uint id, uint lun)
{
        struct Scsi_Host *shost;
        int error = -ENXIO;

        shost = scsi_host_lookup(host);
        if (!shost)
                return error;

        if (shost->transportt->user_scan)
                error = shost->transportt->user_scan(shost, channel, id, lun);
        else
                error = scsi_scan_host_selected(shost, channel, id, lun,
                                                SCSI_SCAN_MANUAL);
        scsi_host_put(shost);
        return error;
}

/**
 * scsi_remove_single_device - Respond to user request to remove a device
 * @host: user-supplied decimal integer
 * @channel: user-supplied decimal integer
 * @id: user-supplied decimal integer
 * @lun: user-supplied decimal integer
 *
 * Description: called by writing "scsi remove-single-device" to
 * /proc/scsi/scsi.  Does a scsi_device_lookup() and scsi_remove_device()
 */
static int scsi_remove_single_device(uint host, uint channel, uint id, uint lun)
{
        struct scsi_device *sdev;
        struct Scsi_Host *shost;
        int error = -ENXIO;

        shost = scsi_host_lookup(host);
        if (!shost)
                return error;
        sdev = scsi_device_lookup(shost, channel, id, lun);
        if (sdev) {
                scsi_remove_device(sdev);
                scsi_device_put(sdev);
                error = 0;
        }

        scsi_host_put(shost);
        return error;
}

/**
 * proc_scsi_write - handle writes to /proc/scsi/scsi
 * @file: not used
 * @buf: buffer to write
 * @length: length of buf, at most PAGE_SIZE
 * @ppos: not used
 *
 * Description: this provides a legacy mechanism to add or remove devices by
 * Host, Channel, ID, and Lun.  To use,
 * "echo 'scsi add-single-device 0 1 2 3' > /proc/scsi/scsi" or
 * "echo 'scsi remove-single-device 0 1 2 3' > /proc/scsi/scsi" with
 * "0 1 2 3" replaced by the Host, Channel, Id, and Lun.
 *
 * Note: this seems to be aimed at parallel SCSI. Most modern busses (USB,
 * SATA, Firewire, Fibre Channel, etc) dynamically assign these values to
 * provide a unique identifier and nothing more.
 */


static ssize_t proc_scsi_write(struct file *file, const char __user *buf,
                               size_t length, loff_t *ppos)
{
        int host, channel, id, lun;
        char *buffer, *end, *p;
        int err;

        if (!buf || length > PAGE_SIZE)
                return -EINVAL;

        buffer = (char *)__get_free_page(GFP_KERNEL);
        if (!buffer)
                return -ENOMEM;

        err = -EFAULT;
        if (copy_from_user(buffer, buf, length))
                goto out;

        err = -EINVAL;
        if (length < PAGE_SIZE) {
                end = buffer + length;
                *end = '\0';
        } else {
                end = buffer + PAGE_SIZE - 1;
                if (*end)
                        goto out;
        }

        /*
         * Usage: echo "scsi add-single-device 0 1 2 3" >/proc/scsi/scsi
         * with  "0 1 2 3" replaced by your "Host Channel Id Lun".
         */
        if (!strncmp("scsi add-single-device", buffer, 22)) {
                p = buffer + 23;

                host    = (p     < end) ? simple_strtoul(p, &p, 0) : 0;
                channel = (p + 1 < end) ? simple_strtoul(p + 1, &p, 0) : 0;
                id      = (p + 1 < end) ? simple_strtoul(p + 1, &p, 0) : 0;
                lun     = (p + 1 < end) ? simple_strtoul(p + 1, &p, 0) : 0;

                err = scsi_add_single_device(host, channel, id, lun);

        /*
         * Usage: echo "scsi remove-single-device 0 1 2 3" >/proc/scsi/scsi
         * with  "0 1 2 3" replaced by your "Host Channel Id Lun".
         */
        } else if (!strncmp("scsi remove-single-device", buffer, 25)) {
                p = buffer + 26;

                host    = (p     < end) ? simple_strtoul(p, &p, 0) : 0;
                channel = (p + 1 < end) ? simple_strtoul(p + 1, &p, 0) : 0;
                id      = (p + 1 < end) ? simple_strtoul(p + 1, &p, 0) : 0;
                lun     = (p + 1 < end) ? simple_strtoul(p + 1, &p, 0) : 0;

                err = scsi_remove_single_device(host, channel, id, lun);
        }

        /*
         * convert success returns so that we return the 
         * number of bytes consumed.
         */
        if (!err)
                err = length;

 out:
        free_page((unsigned long)buffer);
        return err;
}

static inline struct device *next_scsi_device(struct device *start)
{
        struct device *next = bus_find_next_device(&scsi_bus_type, start);

        put_device(start);
        return next;
}

static void *scsi_seq_start(struct seq_file *sfile, loff_t *pos)
{
        struct device *dev = NULL;
        loff_t n = *pos;

        while ((dev = next_scsi_device(dev))) {
                if (!n--)
                        break;
                sfile->private++;
        }
        return dev;
}

static void *scsi_seq_next(struct seq_file *sfile, void *v, loff_t *pos)
{
        (*pos)++;
        sfile->private++;
        return next_scsi_device(v);
}

static void scsi_seq_stop(struct seq_file *sfile, void *v)
{
        put_device(v);
}

static int scsi_seq_show(struct seq_file *sfile, void *dev)
{
        if (!sfile->private)
                seq_puts(sfile, "Attached devices:\n");

        return proc_print_scsidevice(dev, sfile);
}

static const struct seq_operations scsi_seq_ops = {
        .start  = scsi_seq_start,
        .next   = scsi_seq_next,
        .stop   = scsi_seq_stop,
        .show   = scsi_seq_show
};

/**
 * proc_scsi_open - glue function
 * @inode: not used
 * @file: passed to single_open()
 *
 * Associates proc_scsi_show with this file
 */
static int proc_scsi_open(struct inode *inode, struct file *file)
{
        /*
         * We don't really need this for the write case but it doesn't
         * harm either.
         */
        return seq_open(file, &scsi_seq_ops);
}

static const struct proc_ops scsi_scsi_proc_ops = {
        .proc_open      = proc_scsi_open,
        .proc_read      = seq_read,
        .proc_write     = proc_scsi_write,
        .proc_lseek     = seq_lseek,
        .proc_release   = seq_release,
};

/**
 * scsi_init_procfs - create scsi and scsi/scsi in procfs
 */
int __init scsi_init_procfs(void)
{
        struct proc_dir_entry *pde;

        proc_scsi = proc_mkdir("scsi", NULL);
        if (!proc_scsi)
                goto err1;

        pde = proc_create("scsi/scsi", 0, NULL, &scsi_scsi_proc_ops);
        if (!pde)
                goto err2;

        return 0;

err2:
        remove_proc_entry("scsi", NULL);
err1:
        return -ENOMEM;
}

/**
 * scsi_exit_procfs - Remove scsi/scsi and scsi from procfs
 */
void scsi_exit_procfs(void)
{
        remove_proc_entry("scsi/scsi", NULL);
        remove_proc_entry("scsi", NULL);
}