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dmaengine.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright(c) 2004 - 2006 Intel Corporation. All rights reserved.
*/
/*
* This code implements the DMA subsystem. It provides a HW-neutral interface
* for other kernel code to use asynchronous memory copy capabilities,
* if present, and allows different HW DMA drivers to register as providing
* this capability.
*
* Due to the fact we are accelerating what is already a relatively fast
* operation, the code goes to great lengths to avoid additional overhead,
* such as locking.
*
* LOCKING:
*
* The subsystem keeps a global list of dma_device structs it is protected by a
* mutex, dma_list_mutex.
*
* A subsystem can get access to a channel by calling dmaengine_get() followed
* by dma_find_channel(), or if it has need for an exclusive channel it can call
* dma_request_channel(). Once a channel is allocated a reference is taken
* against its corresponding driver to disable removal.
*
* Each device has a channels list, which runs unlocked but is never modified
* once the device is registered, it's just setup by the driver.
*
* See Documentation/driver-api/dmaengine for more details
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/device.h>
#include <linux/dmaengine.h>
#include <linux/hardirq.h>
#include <linux/spinlock.h>
#include <linux/percpu.h>
#include <linux/rcupdate.h>
#include <linux/mutex.h>
#include <linux/jiffies.h>
#include <linux/rculist.h>
#include <linux/idr.h>
#include <linux/slab.h>
#include <linux/acpi.h>
#include <linux/acpi_dma.h>
#include <linux/of_dma.h>
#include <linux/mempool.h>
#include <linux/numa.h>
#include "dmaengine.h"
static DEFINE_MUTEX(dma_list_mutex);
static DEFINE_IDA(dma_ida);
static LIST_HEAD(dma_device_list);
static long dmaengine_ref_count;
/* --- debugfs implementation --- */
#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>
static struct dentry *rootdir;
static void dmaengine_debug_register(struct dma_device *dma_dev)
{
dma_dev->dbg_dev_root = debugfs_create_dir(dev_name(dma_dev->dev),
rootdir);
if (IS_ERR(dma_dev->dbg_dev_root))
dma_dev->dbg_dev_root = NULL;
}
static void dmaengine_debug_unregister(struct dma_device *dma_dev)
{
debugfs_remove_recursive(dma_dev->dbg_dev_root);
dma_dev->dbg_dev_root = NULL;
}
static void dmaengine_dbg_summary_show(struct seq_file *s,
struct dma_device *dma_dev)
{
struct dma_chan *chan;
list_for_each_entry(chan, &dma_dev->channels, device_node) {
if (chan->client_count) {
seq_printf(s, " %-13s| %s", dma_chan_name(chan),
chan->dbg_client_name ?: "in-use");
if (chan->router)
seq_printf(s, " (via router: %s)\n",
dev_name(chan->router->dev));
else
seq_puts(s, "\n");
}
}
}
static int dmaengine_summary_show(struct seq_file *s, void *data)
{
struct dma_device *dma_dev = NULL;
mutex_lock(&dma_list_mutex);
list_for_each_entry(dma_dev, &dma_device_list, global_node) {
seq_printf(s, "dma%d (%s): number of channels: %u\n",
dma_dev->dev_id, dev_name(dma_dev->dev),
dma_dev->chancnt);
if (dma_dev->dbg_summary_show)
dma_dev->dbg_summary_show(s, dma_dev);
else
dmaengine_dbg_summary_show(s, dma_dev);
if (!list_is_last(&dma_dev->global_node, &dma_device_list))
seq_puts(s, "\n");
}
mutex_unlock(&dma_list_mutex);
return 0;
}
DEFINE_SHOW_ATTRIBUTE(dmaengine_summary);
static void __init dmaengine_debugfs_init(void)
{
rootdir = debugfs_create_dir("dmaengine", NULL);
/* /sys/kernel/debug/dmaengine/summary */
debugfs_create_file("summary", 0444, rootdir, NULL,
&dmaengine_summary_fops);
}
#else
static inline void dmaengine_debugfs_init(void) { }
static inline int dmaengine_debug_register(struct dma_device *dma_dev)
{
return 0;
}
static inline void dmaengine_debug_unregister(struct dma_device *dma_dev) { }
#endif /* DEBUG_FS */
/* --- sysfs implementation --- */
#define DMA_SLAVE_NAME "slave"
/**
* dev_to_dma_chan - convert a device pointer to its sysfs container object
* @dev: device node
*
* Must be called under dma_list_mutex.
*/
static struct dma_chan *dev_to_dma_chan(struct device *dev)
{
struct dma_chan_dev *chan_dev;
chan_dev = container_of(dev, typeof(*chan_dev), device);
return chan_dev->chan;
}
static ssize_t memcpy_count_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct dma_chan *chan;
unsigned long count = 0;
int i;
int err;
mutex_lock(&dma_list_mutex);
chan = dev_to_dma_chan(dev);
if (chan) {
for_each_possible_cpu(i)
count += per_cpu_ptr(chan->local, i)->memcpy_count;
err = sprintf(buf, "%lu\n", count);
} else
err = -ENODEV;
mutex_unlock(&dma_list_mutex);
return err;
}
static DEVICE_ATTR_RO(memcpy_count);
static ssize_t bytes_transferred_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct dma_chan *chan;
unsigned long count = 0;
int i;
int err;
mutex_lock(&dma_list_mutex);
chan = dev_to_dma_chan(dev);
if (chan) {
for_each_possible_cpu(i)
count += per_cpu_ptr(chan->local, i)->bytes_transferred;
err = sprintf(buf, "%lu\n", count);
} else
err = -ENODEV;
mutex_unlock(&dma_list_mutex);
return err;
}
static DEVICE_ATTR_RO(bytes_transferred);
static ssize_t in_use_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct dma_chan *chan;
int err;
mutex_lock(&dma_list_mutex);
chan = dev_to_dma_chan(dev);
if (chan)
err = sprintf(buf, "%d\n", chan->client_count);
else
err = -ENODEV;
mutex_unlock(&dma_list_mutex);
return err;
}
static DEVICE_ATTR_RO(in_use);
static struct attribute *dma_dev_attrs[] = {
&dev_attr_memcpy_count.attr,
&dev_attr_bytes_transferred.attr,
&dev_attr_in_use.attr,
NULL,
};
ATTRIBUTE_GROUPS(dma_dev);
static void chan_dev_release(struct device *dev)
{
struct dma_chan_dev *chan_dev;
chan_dev = container_of(dev, typeof(*chan_dev), device);
kfree(chan_dev);
}
static struct class dma_devclass = {
.name = "dma",
.dev_groups = dma_dev_groups,
.dev_release = chan_dev_release,
};
/* --- client and device registration --- */
/* enable iteration over all operation types */
static dma_cap_mask_t dma_cap_mask_all;
/**
* struct dma_chan_tbl_ent - tracks channel allocations per core/operation
* @chan: associated channel for this entry
*/
struct dma_chan_tbl_ent {
struct dma_chan *chan;
};
/* percpu lookup table for memory-to-memory offload providers */
static struct dma_chan_tbl_ent __percpu *channel_table[DMA_TX_TYPE_END];
static int __init dma_channel_table_init(void)
{
enum dma_transaction_type cap;
int err = 0;
bitmap_fill(dma_cap_mask_all.bits, DMA_TX_TYPE_END);
/* 'interrupt', 'private', and 'slave' are channel capabilities,
* but are not associated with an operation so they do not need
* an entry in the channel_table
*/
clear_bit(DMA_INTERRUPT, dma_cap_mask_all.bits);
clear_bit(DMA_PRIVATE, dma_cap_mask_all.bits);
clear_bit(DMA_SLAVE, dma_cap_mask_all.bits);
for_each_dma_cap_mask(cap, dma_cap_mask_all) {
channel_table[cap] = alloc_percpu(struct dma_chan_tbl_ent);
if (!channel_table[cap]) {
err = -ENOMEM;
break;
}
}
if (err) {
pr_err("dmaengine dma_channel_table_init failure: %d\n", err);
for_each_dma_cap_mask(cap, dma_cap_mask_all)
free_percpu(channel_table[cap]);
}
return err;
}
arch_initcall(dma_channel_table_init);
/**
* dma_chan_is_local - checks if the channel is in the same NUMA-node as the CPU
* @chan: DMA channel to test
* @cpu: CPU index which the channel should be close to
*
* Returns true if the channel is in the same NUMA-node as the CPU.
*/
static bool dma_chan_is_local(struct dma_chan *chan, int cpu)
{
int node = dev_to_node(chan->device->dev);
return node == NUMA_NO_NODE ||
cpumask_test_cpu(cpu, cpumask_of_node(node));
}
/**
* min_chan - finds the channel with min count and in the same NUMA-node as the CPU
* @cap: capability to match
* @cpu: CPU index which the channel should be close to
*
* If some channels are close to the given CPU, the one with the lowest
* reference count is returned. Otherwise, CPU is ignored and only the
* reference count is taken into account.
*
* Must be called under dma_list_mutex.
*/
static struct dma_chan *min_chan(enum dma_transaction_type cap, int cpu)
{
struct dma_device *device;
struct dma_chan *chan;
struct dma_chan *min = NULL;
struct dma_chan *localmin = NULL;
list_for_each_entry(device, &dma_device_list, global_node) {
if (!dma_has_cap(cap, device->cap_mask) ||
dma_has_cap(DMA_PRIVATE, device->cap_mask))
continue;
list_for_each_entry(chan, &device->channels, device_node) {
if (!chan->client_count)
continue;
if (!min || chan->table_count < min->table_count)
min = chan;
if (dma_chan_is_local(chan, cpu))
if (!localmin ||
chan->table_count < localmin->table_count)
localmin = chan;
}
}
chan = localmin ? localmin : min;
if (chan)
chan->table_count++;
return chan;
}
/**
* dma_channel_rebalance - redistribute the available channels
*
* Optimize for CPU isolation (each CPU gets a dedicated channel for an
* operation type) in the SMP case, and operation isolation (avoid
* multi-tasking channels) in the non-SMP case.
*
* Must be called under dma_list_mutex.
*/
static void dma_channel_rebalance(void)
{
struct dma_chan *chan;
struct dma_device *device;
int cpu;
int cap;
/* undo the last distribution */
for_each_dma_cap_mask(cap, dma_cap_mask_all)
for_each_possible_cpu(cpu)
per_cpu_ptr(channel_table[cap], cpu)->chan = NULL;
list_for_each_entry(device, &dma_device_list, global_node) {
if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
continue;
list_for_each_entry(chan, &device->channels, device_node)
chan->table_count = 0;
}
/* don't populate the channel_table if no clients are available */
if (!dmaengine_ref_count)
return;
/* redistribute available channels */
for_each_dma_cap_mask(cap, dma_cap_mask_all)
for_each_online_cpu(cpu) {
chan = min_chan(cap, cpu);
per_cpu_ptr(channel_table[cap], cpu)->chan = chan;
}
}
static int dma_device_satisfies_mask(struct dma_device *device,
const dma_cap_mask_t *want)
{
dma_cap_mask_t has;
bitmap_and(has.bits, want->bits, device->cap_mask.bits,
DMA_TX_TYPE_END);
return bitmap_equal(want->bits, has.bits, DMA_TX_TYPE_END);
}
static struct module *dma_chan_to_owner(struct dma_chan *chan)
{
return chan->device->owner;
}
/**
* balance_ref_count - catch up the channel reference count
* @chan: channel to balance ->client_count versus dmaengine_ref_count
*
* Must be called under dma_list_mutex.
*/
static void balance_ref_count(struct dma_chan *chan)
{
struct module *owner = dma_chan_to_owner(chan);
while (chan->client_count < dmaengine_ref_count) {
__module_get(owner);
chan->client_count++;
}
}
static void dma_device_release(struct kref *ref)
{
struct dma_device *device = container_of(ref, struct dma_device, ref);
list_del_rcu(&device->global_node);
dma_channel_rebalance();
if (device->device_release)
device->device_release(device);
}
static void dma_device_put(struct dma_device *device)
{
lockdep_assert_held(&dma_list_mutex);
kref_put(&device->ref, dma_device_release);
}
/**
* dma_chan_get - try to grab a DMA channel's parent driver module
* @chan: channel to grab
*
* Must be called under dma_list_mutex.
*/
static int dma_chan_get(struct dma_chan *chan)
{
struct module *owner = dma_chan_to_owner(chan);
int ret;
/* The channel is already in use, update client count */
if (chan->client_count) {
__module_get(owner);
goto out;
}
if (!try_module_get(owner))
return -ENODEV;
ret = kref_get_unless_zero(&chan->device->ref);
if (!ret) {
ret = -ENODEV;
goto module_put_out;
}
/* allocate upon first client reference */
if (chan->device->device_alloc_chan_resources) {
ret = chan->device->device_alloc_chan_resources(chan);
if (ret < 0)
goto err_out;
}
if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
balance_ref_count(chan);
out:
chan->client_count++;
return 0;
err_out:
dma_device_put(chan->device);
module_put_out:
module_put(owner);
return ret;
}
/**
* dma_chan_put - drop a reference to a DMA channel's parent driver module
* @chan: channel to release
*
* Must be called under dma_list_mutex.
*/
static void dma_chan_put(struct dma_chan *chan)
{
/* This channel is not in use, bail out */
if (!chan->client_count)
return;
chan->client_count--;
/* This channel is not in use anymore, free it */
if (!chan->client_count && chan->device->device_free_chan_resources) {
/* Make sure all operations have completed */
dmaengine_synchronize(chan);
chan->device->device_free_chan_resources(chan);
}
/* If the channel is used via a DMA request router, free the mapping */
if (chan->router && chan->router->route_free) {
chan->router->route_free(chan->router->dev, chan->route_data);
chan->router = NULL;
chan->route_data = NULL;
}
dma_device_put(chan->device);
module_put(dma_chan_to_owner(chan));
}
enum dma_status dma_sync_wait(struct dma_chan *chan, dma_cookie_t cookie)
{
enum dma_status status;
unsigned long dma_sync_wait_timeout = jiffies + msecs_to_jiffies(5000);
dma_async_issue_pending(chan);
do {
status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);
if (time_after_eq(jiffies, dma_sync_wait_timeout)) {
dev_err(chan->device->dev, "%s: timeout!\n", __func__);
return DMA_ERROR;
}
if (status != DMA_IN_PROGRESS)
break;
cpu_relax();
} while (1);
return status;
}
EXPORT_SYMBOL(dma_sync_wait);
/**
* dma_find_channel - find a channel to carry out the operation
* @tx_type: transaction type
*/
struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type)
{
return this_cpu_read(channel_table[tx_type]->chan);
}
EXPORT_SYMBOL(dma_find_channel);
/**
* dma_issue_pending_all - flush all pending operations across all channels
*/
void dma_issue_pending_all(void)
{
struct dma_device *device;
struct dma_chan *chan;
rcu_read_lock();
list_for_each_entry_rcu(device, &dma_device_list, global_node) {
if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
continue;
list_for_each_entry(chan, &device->channels, device_node)
if (chan->client_count)
device->device_issue_pending(chan);
}
rcu_read_unlock();
}
EXPORT_SYMBOL(dma_issue_pending_all);
int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps)
{
struct dma_device *device;
if (!chan || !caps)
return -EINVAL;
device = chan->device;
/* check if the channel supports slave transactions */
if (!(test_bit(DMA_SLAVE, device->cap_mask.bits) ||
test_bit(DMA_CYCLIC, device->cap_mask.bits)))
return -ENXIO;
/*
* Check whether it reports it uses the generic slave
* capabilities, if not, that means it doesn't support any
* kind of slave capabilities reporting.
*/
if (!device->directions)
return -ENXIO;
caps->src_addr_widths = device->src_addr_widths;
caps->dst_addr_widths = device->dst_addr_widths;
caps->directions = device->directions;
caps->min_burst = device->min_burst;
caps->max_burst = device->max_burst;
caps->max_sg_burst = device->max_sg_burst;
caps->residue_granularity = device->residue_granularity;
caps->descriptor_reuse = device->descriptor_reuse;
caps->cmd_pause = !!device->device_pause;
caps->cmd_resume = !!device->device_resume;
caps->cmd_terminate = !!device->device_terminate_all;
/*
* DMA engine device might be configured with non-uniformly
* distributed slave capabilities per device channels. In this
* case the corresponding driver may provide the device_caps
* callback to override the generic capabilities with
* channel-specific ones.
*/
if (device->device_caps)
device->device_caps(chan, caps);
return 0;
}
EXPORT_SYMBOL_GPL(dma_get_slave_caps);
static struct dma_chan *private_candidate(const dma_cap_mask_t *mask,
struct dma_device *dev,
dma_filter_fn fn, void *fn_param)
{
struct dma_chan *chan;
if (mask && !dma_device_satisfies_mask(dev, mask)) {
dev_dbg(dev->dev, "%s: wrong capabilities\n", __func__);
return NULL;
}
/* devices with multiple channels need special handling as we need to
* ensure that all channels are either private or public.
*/
if (dev->chancnt > 1 && !dma_has_cap(DMA_PRIVATE, dev->cap_mask))
list_for_each_entry(chan, &dev->channels, device_node) {
/* some channels are already publicly allocated */
if (chan->client_count)
return NULL;
}
list_for_each_entry(chan, &dev->channels, device_node) {
if (chan->client_count) {
dev_dbg(dev->dev, "%s: %s busy\n",
__func__, dma_chan_name(chan));
continue;
}
if (fn && !fn(chan, fn_param)) {
dev_dbg(dev->dev, "%s: %s filter said false\n",
__func__, dma_chan_name(chan));
continue;
}
return chan;
}
return NULL;
}
static struct dma_chan *find_candidate(struct dma_device *device,
const dma_cap_mask_t *mask,
dma_filter_fn fn, void *fn_param)
{
struct dma_chan *chan = private_candidate(mask, device, fn, fn_param);
int err;
if (chan) {
/* Found a suitable channel, try to grab, prep, and return it.
* We first set DMA_PRIVATE to disable balance_ref_count as this
* channel will not be published in the general-purpose
* allocator
*/
dma_cap_set(DMA_PRIVATE, device->cap_mask);
device->privatecnt++;
err = dma_chan_get(chan);
if (err) {
if (err == -ENODEV) {
dev_dbg(device->dev, "%s: %s module removed\n",
__func__, dma_chan_name(chan));
list_del_rcu(&device->global_node);
} else
dev_dbg(device->dev,
"%s: failed to get %s: (%d)\n",
__func__, dma_chan_name(chan), err);
if (--device->privatecnt == 0)
dma_cap_clear(DMA_PRIVATE, device->cap_mask);
chan = ERR_PTR(err);
}
}
return chan ? chan : ERR_PTR(-EPROBE_DEFER);
}
/**
* dma_get_slave_channel - try to get specific channel exclusively
* @chan: target channel
*/
struct dma_chan *dma_get_slave_channel(struct dma_chan *chan)
{
/* lock against __dma_request_channel */
mutex_lock(&dma_list_mutex);
if (chan->client_count == 0) {
struct dma_device *device = chan->device;
int err;
dma_cap_set(DMA_PRIVATE, device->cap_mask);
device->privatecnt++;
err = dma_chan_get(chan);
if (err) {
dev_dbg(chan->device->dev,
"%s: failed to get %s: (%d)\n",
__func__, dma_chan_name(chan), err);
chan = NULL;
if (--device->privatecnt == 0)
dma_cap_clear(DMA_PRIVATE, device->cap_mask);
}
} else
chan = NULL;
mutex_unlock(&dma_list_mutex);
return chan;
}
EXPORT_SYMBOL_GPL(dma_get_slave_channel);
struct dma_chan *dma_get_any_slave_channel(struct dma_device *device)
{
dma_cap_mask_t mask;
struct dma_chan *chan;
dma_cap_zero(mask);
dma_cap_set(DMA_SLAVE, mask);
/* lock against __dma_request_channel */
mutex_lock(&dma_list_mutex);
chan = find_candidate(device, &mask, NULL, NULL);
mutex_unlock(&dma_list_mutex);
return IS_ERR(chan) ? NULL : chan;
}
EXPORT_SYMBOL_GPL(dma_get_any_slave_channel);
/**
* __dma_request_channel - try to allocate an exclusive channel
* @mask: capabilities that the channel must satisfy
* @fn: optional callback to disposition available channels
* @fn_param: opaque parameter to pass to dma_filter_fn()
* @np: device node to look for DMA channels
*
* Returns pointer to appropriate DMA channel on success or NULL.
*/
struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
dma_filter_fn fn, void *fn_param,
struct device_node *np)
{
struct dma_device *device, *_d;
struct dma_chan *chan = NULL;
/* Find a channel */
mutex_lock(&dma_list_mutex);
list_for_each_entry_safe(device, _d, &dma_device_list, global_node) {
/* Finds a DMA controller with matching device node */
if (np && device->dev->of_node && np != device->dev->of_node)
continue;
chan = find_candidate(device, mask, fn, fn_param);
if (!IS_ERR(chan))
break;
chan = NULL;
}
mutex_unlock(&dma_list_mutex);
pr_debug("%s: %s (%s)\n",
__func__,
chan ? "success" : "fail",
chan ? dma_chan_name(chan) : NULL);
return chan;
}
EXPORT_SYMBOL_GPL(__dma_request_channel);
static const struct dma_slave_map *dma_filter_match(struct dma_device *device,
const char *name,
struct device *dev)
{
int i;
if (!device->filter.mapcnt)
return NULL;
for (i = 0; i < device->filter.mapcnt; i++) {
const struct dma_slave_map *map = &device->filter.map[i];
if (!strcmp(map->devname, dev_name(dev)) &&
!strcmp(map->slave, name))
return map;
}
return NULL;
}
/**
* dma_request_chan - try to allocate an exclusive slave channel
* @dev: pointer to client device structure
* @name: slave channel name
*
* Returns pointer to appropriate DMA channel on success or an error pointer.
*/
struct dma_chan *dma_request_chan(struct device *dev, const char *name)
{
struct dma_device *d, *_d;
struct dma_chan *chan = NULL;
/* If device-tree is present get slave info from here */
if (dev->of_node)
chan = of_dma_request_slave_channel(dev->of_node, name);
/* If device was enumerated by ACPI get slave info from here */
if (has_acpi_companion(dev) && !chan)
chan = acpi_dma_request_slave_chan_by_name(dev, name);
if (PTR_ERR(chan) == -EPROBE_DEFER)
return chan;
if (!IS_ERR_OR_NULL(chan))
goto found;
/* Try to find the channel via the DMA filter map(s) */
mutex_lock(&dma_list_mutex);
list_for_each_entry_safe(d, _d, &dma_device_list, global_node) {
dma_cap_mask_t mask;
const struct dma_slave_map *map = dma_filter_match(d, name, dev);
if (!map)
continue;
dma_cap_zero(mask);
dma_cap_set(DMA_SLAVE, mask);
chan = find_candidate(d, &mask, d->filter.fn, map->param);
if (!IS_ERR(chan))
break;
}
mutex_unlock(&dma_list_mutex);
if (IS_ERR(chan))
return chan;
if (!chan)
return ERR_PTR(-EPROBE_DEFER);
found:
#ifdef CONFIG_DEBUG_FS
chan->dbg_client_name = kasprintf(GFP_KERNEL, "%s:%s", dev_name(dev),
name);
#endif
chan->name = kasprintf(GFP_KERNEL, "dma:%s", name);
if (!chan->name)
return chan;
chan->slave = dev;
if (sysfs_create_link(&chan->dev->device.kobj, &dev->kobj,
DMA_SLAVE_NAME))
dev_warn(dev, "Cannot create DMA %s symlink\n", DMA_SLAVE_NAME);
if (sysfs_create_link(&dev->kobj, &chan->dev->device.kobj, chan->name))
dev_warn(dev, "Cannot create DMA %s symlink\n", chan->name);
return chan;
}
EXPORT_SYMBOL_GPL(dma_request_chan);
/**
* dma_request_chan_by_mask - allocate a channel satisfying certain capabilities
* @mask: capabilities that the channel must satisfy
*
* Returns pointer to appropriate DMA channel on success or an error pointer.
*/
struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask)
{
struct dma_chan *chan;
if (!mask)
return ERR_PTR(-ENODEV);
chan = __dma_request_channel(mask, NULL, NULL, NULL);
if (!chan) {
mutex_lock(&dma_list_mutex);
if (list_empty(&dma_device_list))
chan = ERR_PTR(-EPROBE_DEFER);
else
chan = ERR_PTR(-ENODEV);
mutex_unlock(&dma_list_mutex);
}
return chan;
}
EXPORT_SYMBOL_GPL(dma_request_chan_by_mask);
void dma_release_channel(struct dma_chan *chan)
{
mutex_lock(&dma_list_mutex);
WARN_ONCE(chan->client_count != 1,
"chan reference count %d != 1\n", chan->client_count);
dma_chan_put(chan);
/* drop PRIVATE cap enabled by __dma_request_channel() */
if (--chan->device->privatecnt == 0)
dma_cap_clear(DMA_PRIVATE, chan->device->cap_mask);
if (chan->slave) {
sysfs_remove_link(&chan->dev->device.kobj, DMA_SLAVE_NAME);
sysfs_remove_link(&chan->slave->kobj, chan->name);
kfree(chan->name);
chan->name = NULL;
chan->slave = NULL;
}
#ifdef CONFIG_DEBUG_FS
kfree(chan->dbg_client_name);
chan->dbg_client_name = NULL;
#endif
mutex_unlock(&dma_list_mutex);
}
EXPORT_SYMBOL_GPL(dma_release_channel);
/**
* dmaengine_get - register interest in dma_channels
*/
void dmaengine_get(void)
{
struct dma_device *device, *_d;
struct dma_chan *chan;
int err;
mutex_lock(&dma_list_mutex);
dmaengine_ref_count++;
/* try to grab channels */
list_for_each_entry_safe(device, _d, &dma_device_list, global_node) {
if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
continue;
list_for_each_entry(chan, &device->channels, device_node) {
err = dma_chan_get(chan);
if (err == -ENODEV) {
/* module removed before we could use it */
list_del_rcu(&device->global_node);
break;
} else if (err)
dev_dbg(chan->device->dev,
"%s: failed to get %s: (%d)\n",
__func__, dma_chan_name(chan), err);
}
}
/* if this is the first reference and there were channels
* waiting we need to rebalance to get those channels
* incorporated into the channel table
*/
if (dmaengine_ref_count == 1)
dma_channel_rebalance();
mutex_unlock(&dma_list_mutex);
}
EXPORT_SYMBOL(dmaengine_get);
/**
* dmaengine_put - let DMA drivers be removed when ref_count == 0
*/
void dmaengine_put(void)
{
struct dma_device *device, *_d;
struct dma_chan *chan;
mutex_lock(&dma_list_mutex);
dmaengine_ref_count--;
BUG_ON(dmaengine_ref_count < 0);
/* drop channel references */
list_for_each_entry_safe(device, _d, &dma_device_list, global_node) {
if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
continue;
list_for_each_entry(chan, &device->channels, device_node)
dma_chan_put(chan);
}
mutex_unlock(&dma_list_mutex);
}
EXPORT_SYMBOL(dmaengine_put);
static bool device_has_all_tx_types(struct dma_device *device)
{
/* A device that satisfies this test has channels that will never cause
* an async_tx channel switch event as all possible operation types can
* be handled.
*/
#ifdef CONFIG_ASYNC_TX_DMA
if (!dma_has_cap(DMA_INTERRUPT, device->cap_mask))
return false;
#endif
#if IS_ENABLED(CONFIG_ASYNC_MEMCPY)