proc_devtree.c

Go to the documentation of this file.

/*
 * proc_devtree.c - handles /proc/device-tree
 *
 * Copyright 1997 Paul Mackerras
 */
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/time.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/of.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <asm/prom.h>
#include <asm/uaccess.h>
#include "internal.h"

static inline void set_node_proc_entry(struct device_node *np,
                       struct proc_dir_entry *de)
{
#ifdef HAVE_ARCH_DEVTREE_FIXUPS
    np->pde = de;
#endif
}

static struct proc_dir_entry *proc_device_tree;

/*
 * Supply data on a read from /proc/device-tree/node/property.
 */
static int property_proc_show(struct seq_file *m, void *v)
{
    struct property *pp = m->private;

    seq_write(m, pp->value, pp->length);
    return 0;
}

static int property_proc_open(struct inode *inode, struct file *file)
{
    return single_open(file, property_proc_show, PDE(inode)->data);
}

static const struct file_operations property_proc_fops = {
    .owner      = THIS_MODULE,
    .open       = property_proc_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = single_release,
};

/*
 * For a node with a name like "gc@10", we make symlinks called "gc"
 * and "@10" to it.
 */

/*
 * Add a property to a node
 */
static struct proc_dir_entry *
__proc_device_tree_add_prop(struct proc_dir_entry *de, struct property *pp,
        const char *name)
{
    struct proc_dir_entry *ent;

    /*
     * Unfortunately proc_register puts each new entry
     * at the beginning of the list.  So we rearrange them.
     */
    ent = proc_create_data(name,
                   strncmp(name, "security-", 9) ? S_IRUGO : S_IRUSR,
                   de, &property_proc_fops, pp);
    if (ent == NULL)
        return NULL;

    if (!strncmp(name, "security-", 9))
        ent->size = 0; /* don't leak number of password chars */
    else
        ent->size = pp->length;

    return ent;
}


void proc_device_tree_add_prop(struct proc_dir_entry *pde, struct property *prop)
{
    __proc_device_tree_add_prop(pde, prop, prop->name);
}

void proc_device_tree_remove_prop(struct proc_dir_entry *pde,
                  struct property *prop)
{
    remove_proc_entry(prop->name, pde);
}

void proc_device_tree_update_prop(struct proc_dir_entry *pde,
                  struct property *newprop,
                  struct property *oldprop)
{
    struct proc_dir_entry *ent;

    if (!oldprop) {
        proc_device_tree_add_prop(pde, newprop);
        return;
    }

    for (ent = pde->subdir; ent != NULL; ent = ent->next)
        if (ent->data == oldprop)
            break;
    if (ent == NULL) {
        printk(KERN_WARNING "device-tree: property \"%s\" "
               " does not exist\n", oldprop->name);
    } else {
        ent->data = newprop;
        ent->size = newprop->length;
    }
}

/*
 * Various dodgy firmware might give us nodes and/or properties with
 * conflicting names. That's generally ok, except for exporting via /proc,
 * so munge names here to ensure they're unique.
 */

static int duplicate_name(struct proc_dir_entry *de, const char *name)
{
    struct proc_dir_entry *ent;
    int found = 0;

    spin_lock(&proc_subdir_lock);

    for (ent = de->subdir; ent != NULL; ent = ent->next) {
        if (strcmp(ent->name, name) == 0) {
            found = 1;
            break;
        }
    }

    spin_unlock(&proc_subdir_lock);

    return found;
}

static const char *fixup_name(struct device_node *np, struct proc_dir_entry *de,
        const char *name)
{
    char *fixed_name;
    int fixup_len = strlen(name) + 2 + 1; /* name + #x + \0 */
    int i = 1, size;

realloc:
    fixed_name = kmalloc(fixup_len, GFP_KERNEL);
    if (fixed_name == NULL) {
        printk(KERN_ERR "device-tree: Out of memory trying to fixup "
                "name \"%s\"\n", name);
        return name;
    }

retry:
    size = snprintf(fixed_name, fixup_len, "%s#%d", name, i);
    size++; /* account for NULL */

    if (size > fixup_len) {
        /* We ran out of space, free and reallocate. */
        kfree(fixed_name);
        fixup_len = size;
        goto realloc;
    }

    if (duplicate_name(de, fixed_name)) {
        /* Multiple duplicates. Retry with a different offset. */
        i++;
        goto retry;
    }

    printk(KERN_WARNING "device-tree: Duplicate name in %s, "
            "renamed to \"%s\"\n", np->full_name, fixed_name);

    return fixed_name;
}

/*
 * Process a node, adding entries for its children and its properties.
 */
void proc_device_tree_add_node(struct device_node *np,
                   struct proc_dir_entry *de)
{
    struct property *pp;
    struct proc_dir_entry *ent;
    struct device_node *child;
    const char *p;

    set_node_proc_entry(np, de);
    for (child = NULL; (child = of_get_next_child(np, child));) {
        /* Use everything after the last slash, or the full name */
        p = strrchr(child->full_name, '/');
        if (!p)
            p = child->full_name;
        else
            ++p;

        if (duplicate_name(de, p))
            p = fixup_name(np, de, p);

        ent = proc_mkdir(p, de);
        if (ent == NULL)
            break;
        proc_device_tree_add_node(child, ent);
    }
    of_node_put(child);

    for (pp = np->properties; pp != NULL; pp = pp->next) {
        p = pp->name;

        if (strchr(p, '/'))
            continue;

        if (duplicate_name(de, p))
            p = fixup_name(np, de, p);

        ent = __proc_device_tree_add_prop(de, pp, p);
        if (ent == NULL)
            break;
    }
}

/*
 * Called on initialization to set up the /proc/device-tree subtree
 */
void __init proc_device_tree_init(void)
{
    struct device_node *root;

    proc_device_tree = proc_mkdir("device-tree", NULL);
    if (proc_device_tree == NULL)
        return;
    root = of_find_node_by_path("/");
    if (root == NULL) {
        pr_debug("/proc/device-tree: can't find root\n");
        return;
    }
    proc_device_tree_add_node(root, proc_device_tree);
    of_node_put(root);
}