// 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);}#elsestatic 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--; 

Lines 1–500 of 1659. Load more