/*
* Copyright (C) 2008 Advanced Micro Devices, Inc.
*
* Author: Joerg Roedel <joerg.roedel@amd.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/dma-debug.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/slab.h>
#define HASH_SIZE 1024ULL
#define HASH_FN_SHIFT 13
#define HASH_FN_MASK (HASH_SIZE - 1)
enum {
dma_debug_single,
dma_debug_page,
dma_debug_sg,
dma_debug_coherent,
};
struct dma_debug_entry {
struct list_head list;
struct device *dev;
int type;
phys_addr_t paddr;
u64 dev_addr;
u64 size;
int direction;
int sg_call_ents;
int sg_mapped_ents;
};
struct hash_bucket {
struct list_head list;
spinlock_t lock;
} __cacheline_aligned_in_smp;
/* Hash list to save the allocated dma addresses */
static struct hash_bucket dma_entry_hash[HASH_SIZE];
/* List of pre-allocated dma_debug_entry's */
static LIST_HEAD(free_entries);
/* Lock for the list above */
static DEFINE_SPINLOCK(free_entries_lock);
/* Global disable flag - will be set in case of an error */
static bool global_disable __read_mostly;
static u32 num_free_entries;
static u32 min_free_entries;
/* number of preallocated entries requested by kernel cmdline */
static u32 req_entries;
/*
* Hash related functions
*
* Every DMA-API request is saved into a struct dma_debug_entry. To
* have quick access to these structs they are stored into a hash.
*/
static int hash_fn(struct dma_debug_entry *entry)
{
/*
* Hash function is based on the dma address.
* We use bits 20-27 here as the index into the hash
*/
return (entry->dev_addr >> HASH_FN_SHIFT) & HASH_FN_MASK;
}
/*
* Request exclusive access to a hash bucket for a given dma_debug_entry.
*/
static struct hash_bucket *get_hash_bucket(struct dma_debug_entry *entry,
unsigned long *flags)
{
int idx = hash_fn(entry);
unsigned long __flags;
spin_lock_irqsave(&dma_entry_hash[idx].lock, __flags);
*flags = __flags;
return &dma_entry_hash[idx];
}
/*
* Give up exclusive access to the hash bucket
*/
static void put_hash_bucket(struct hash_bucket *bucket,
unsigned long *flags)
{
unsigned long __flags = *flags;
spin_unlock_irqrestore(&bucket->lock, __flags);
}
/*
* Search a given entry in the hash bucket list
*/
static struct dma_debug_entry *hash_bucket_find(struct hash_bucket *bucket,
struct dma_debug_entry *ref)
{
struct dma_debug_entry *entry;
list_for_each_entry(entry, &bucket->list, list) {
if ((entry->dev_addr == ref->dev_addr) &&
(entry->dev == ref->dev))
return entry;
}
return NULL;
}
/*
* Add an entry to a hash bucket
*/
static void hash_bucket_add(struct hash_bucket *bucket,
struct dma_debug_entry *entry)
{
list_add_tail(&entry->list, &bucket->list);
}
/*
* Remove entry from a hash bucket list
*/
static void hash_bucket_del(struct dma_debug_entry *entry)
{
list_del(&entry->list);
}
/*
* Wrapper function for adding an entry to the hash.
* This function takes care of locking itself.
*/
static void add_dma_entry(struct dma_debug_entry *entry)
{
struct hash_bucket *bucket;
unsigned long flags;
bucket = get_hash_bucket(entry, &flags);
hash_bucket_add(bucket, entry);
put_hash_bucket(bucket, &flags);
}
/* struct dma_entry allocator
*
* The next two functions implement the allocator for
* struct dma_debug_entries.
*/
static struct dma_debug_entry *dma_entry_alloc(void)
{
struct dma_debug_entry *entry = NULL;
unsigned long flags;
spin_lock_irqsave(&free_entries_lock, flags);
if (list_empty(&free_entries)) {
printk(KERN_ERR "DMA-API: debugging out of memory "
"- disabling\n");
global_disable = true;
goto out;
}
entry = list_entry(free_entries.next, struct dma_debug_entry, list);
list_del(&entry->list);
memset(entry, 0, sizeof(*entry));
num_free_entries -= 1;
if (num_free_entries < min_free_entries)
min_free_entries = num_free_entries;
out:
spin_unlock_irqrestore(&free_entries_lock, flags);
return entry;
}
static void dma_entry_free(struct dma_debug_entry *entry)
{
unsigned long flags;
/*
* add to beginning of the list - this way the entries are
* more likely cache hot when they are reallocated.
*/
spin_lock_irqsave(&free_entries_lock, flags);
list_add(&entry->list, &free_entries);
num_free_entries += 1;
spin_unlock_irqrestore(&free_entries_lock, flags);
}
/*
* DMA-API debugging init code
*
* The init code does two things:
* 1. Initialize core data structures
* 2. Preallocate a given number of dma_debug_entry structs
*/
static int prealloc_memory(u32 num_entries)
{
struct dma_debug_entry *entry, *next_entry;
int i;
for (i = 0; i < num_entries; ++i) {
entry = kzalloc(sizeof(*entry), GFP_KERNEL);
if (!entry)
goto out_err;
list_add_tail(&entry->list, &free_entries);
}
num_free_entries = num_entries;
min_free_entries = num_entries;
printk(KERN_INFO "DMA-API: preallocated %d debug entries\n",
num_entries);
return 0;
out_err:
list_for_each_entry_safe(entry, next_entry, &free_entries, list) {
list_del(&entry->list);
kfree(entry);
}
return -ENOMEM;
}
/*
* Let the architectures decide how many entries should be preallocated.
*/
void dma_debug_init(u32 num_entries)
{
int i;
if (global_disable)
return;
for (i = 0; i < HASH_SIZE; ++i) {
INIT_LIST_HEAD(&dma_entry_hash[i].list);
dma_entry_hash[i].lock = SPIN_LOCK_UNLOCKED;
}
if (req_entries)
num_entries = req_entries;
if (prealloc_memory(num_entries) != 0) {
printk(KERN_ERR "DMA-API: debugging out of memory error "
"- disabled\n");
global_disable = true;
return;
}
printk(KERN_INFO "DMA-API: debugging enabled by kernel config\n");
}
static __init int dma_debug_cmdline(char *str)
{
if (!str)
return -EINVAL;
if (strncmp(str, "off", 3) == 0) {
printk(KERN_INFO "DMA-API: debugging disabled on kernel "
"command line\n");
global_disable = true;
}
return 0;
}
static __init int dma_debug_entries_cmdline(char *str)
{
int res;
if (!str)
return -EINVAL;
res = get_option(&str, &req_entries);
if (!res)
req_entries = 0;
return 0;
}
__setup("dma_debug=", dma_debug_cmdline);
__setup("dma_debug_entries=", dma_debug_entries_cmdline);
