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![Benjamin Herrenschmidt](/assets/img/avatar_default.png)
The current debugfs interface to scom is essentially unused and racy. It uses two different files "address" and "data" to perform accesses which is at best impractical for anything but manual use by a developer. This replaces it with an "access" file which represent the entire scom address space which can be lseek/read/writen too. This file only supports accesses that are 8 bytes aligned and multiple of 8 bytes in size. The offset is logically the SCOM address multiplied by 8. Since nothing in userspace exploits that file at the moment, the ABI change is a no-brainer. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
237 lines
5.4 KiB
C
237 lines
5.4 KiB
C
/*
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* Copyright 2010 Benjamin Herrenschmidt, IBM Corp
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* <benh@kernel.crashing.org>
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* and David Gibson, IBM Corporation.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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* the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/kernel.h>
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#include <linux/debugfs.h>
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#include <linux/slab.h>
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#include <linux/export.h>
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#include <asm/debug.h>
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#include <asm/prom.h>
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#include <asm/scom.h>
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#include <asm/uaccess.h>
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const struct scom_controller *scom_controller;
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EXPORT_SYMBOL_GPL(scom_controller);
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struct device_node *scom_find_parent(struct device_node *node)
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{
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struct device_node *par, *tmp;
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const u32 *p;
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for (par = of_node_get(node); par;) {
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if (of_get_property(par, "scom-controller", NULL))
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break;
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p = of_get_property(par, "scom-parent", NULL);
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tmp = par;
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if (p == NULL)
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par = of_get_parent(par);
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else
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par = of_find_node_by_phandle(*p);
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of_node_put(tmp);
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}
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return par;
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}
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EXPORT_SYMBOL_GPL(scom_find_parent);
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scom_map_t scom_map_device(struct device_node *dev, int index)
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{
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struct device_node *parent;
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unsigned int cells, size;
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const __be32 *prop, *sprop;
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u64 reg, cnt;
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scom_map_t ret;
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parent = scom_find_parent(dev);
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if (parent == NULL)
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return 0;
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/*
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* We support "scom-reg" properties for adding scom registers
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* to a random device-tree node with an explicit scom-parent
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*
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* We also support the simple "reg" property if the device is
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* a direct child of a scom controller.
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*
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* In case both exist, "scom-reg" takes precedence.
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*/
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prop = of_get_property(dev, "scom-reg", &size);
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sprop = of_get_property(parent, "#scom-cells", NULL);
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if (!prop && parent == dev->parent) {
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prop = of_get_property(dev, "reg", &size);
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sprop = of_get_property(parent, "#address-cells", NULL);
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}
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if (!prop)
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return NULL;
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cells = sprop ? be32_to_cpup(sprop) : 1;
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size >>= 2;
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if (index >= (size / (2*cells)))
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return 0;
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reg = of_read_number(&prop[index * cells * 2], cells);
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cnt = of_read_number(&prop[index * cells * 2 + cells], cells);
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ret = scom_map(parent, reg, cnt);
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of_node_put(parent);
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return ret;
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}
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EXPORT_SYMBOL_GPL(scom_map_device);
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#ifdef CONFIG_SCOM_DEBUGFS
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struct scom_debug_entry {
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struct device_node *dn;
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struct debugfs_blob_wrapper path;
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char name[16];
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};
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static ssize_t scom_debug_read(struct file *filp, char __user *ubuf,
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size_t count, loff_t *ppos)
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{
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struct scom_debug_entry *ent = filp->private_data;
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u64 __user *ubuf64 = (u64 __user *)ubuf;
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loff_t off = *ppos;
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ssize_t done = 0;
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u64 reg, reg_cnt, val;
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scom_map_t map;
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int rc;
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if (off < 0 || (off & 7) || (count & 7))
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return -EINVAL;
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reg = off >> 3;
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reg_cnt = count >> 3;
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map = scom_map(ent->dn, reg, reg_cnt);
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if (!scom_map_ok(map))
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return -ENXIO;
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for (reg = 0; reg < reg_cnt; reg++) {
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rc = scom_read(map, reg, &val);
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if (!rc)
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rc = put_user(val, ubuf64);
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if (rc) {
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if (!done)
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done = rc;
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break;
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}
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ubuf64++;
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*ppos += 8;
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done += 8;
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}
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scom_unmap(map);
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return done;
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}
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static ssize_t scom_debug_write(struct file* filp, const char __user *ubuf,
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size_t count, loff_t *ppos)
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{
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struct scom_debug_entry *ent = filp->private_data;
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u64 __user *ubuf64 = (u64 __user *)ubuf;
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loff_t off = *ppos;
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ssize_t done = 0;
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u64 reg, reg_cnt, val;
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scom_map_t map;
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int rc;
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if (off < 0 || (off & 7) || (count & 7))
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return -EINVAL;
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reg = off >> 3;
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reg_cnt = count >> 3;
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map = scom_map(ent->dn, reg, reg_cnt);
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if (!scom_map_ok(map))
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return -ENXIO;
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for (reg = 0; reg < reg_cnt; reg++) {
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rc = get_user(val, ubuf64);
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if (!rc)
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rc = scom_write(map, reg, val);
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if (rc) {
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if (!done)
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done = rc;
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break;
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}
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ubuf64++;
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done += 8;
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}
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scom_unmap(map);
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return done;
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}
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static const struct file_operations scom_debug_fops = {
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.read = scom_debug_read,
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.write = scom_debug_write,
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.open = simple_open,
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.llseek = default_llseek,
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};
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static int scom_debug_init_one(struct dentry *root, struct device_node *dn,
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int i)
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{
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struct scom_debug_entry *ent;
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struct dentry *dir;
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ent = kzalloc(sizeof(*ent), GFP_KERNEL);
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if (!ent)
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return -ENOMEM;
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ent->dn = of_node_get(dn);
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snprintf(ent->name, 16, "%08x", i);
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ent->path.data = (void*) dn->full_name;
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ent->path.size = strlen(dn->full_name);
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dir = debugfs_create_dir(ent->name, root);
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if (!dir) {
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of_node_put(dn);
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kfree(ent);
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return -1;
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}
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debugfs_create_blob("devspec", 0400, dir, &ent->path);
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debugfs_create_file("access", 0600, dir, ent, &scom_debug_fops);
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return 0;
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}
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static int scom_debug_init(void)
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{
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struct device_node *dn;
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struct dentry *root;
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int i, rc;
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root = debugfs_create_dir("scom", powerpc_debugfs_root);
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if (!root)
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return -1;
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i = rc = 0;
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for_each_node_with_property(dn, "scom-controller") {
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int id = of_get_ibm_chip_id(dn);
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if (id == -1)
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id = i;
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rc |= scom_debug_init_one(root, dn, id);
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i++;
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}
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return rc;
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}
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device_initcall(scom_debug_init);
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#endif /* CONFIG_SCOM_DEBUGFS */
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