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* Copyright(c) 2004 - 2006 Intel Corporation. All rights reserved.
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
* 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.
* The full GNU General Public License is included in this distribution in the
* file called COPYING.
#include <linux/device.h>
#include <linux/uio.h>
#include <linux/kref.h>
#include <linux/completion.h>
#include <linux/rcupdate.h>
#include <linux/dma-mapping.h>
* enum dma_state - resource PNP/power management state
* @DMA_RESOURCE_SUSPEND: DMA device going into low power state
* @DMA_RESOURCE_RESUME: DMA device returning to full power
* @DMA_RESOURCE_AVAILABLE: DMA device available to the system
* @DMA_RESOURCE_REMOVED: DMA device removed from the system
enum dma_state {
* enum dma_state_client - state of the channel in the client
* @DMA_ACK: client would like to use, or was using this channel
* @DMA_DUP: client has already seen this channel, or is not using this channel
* @DMA_NAK: client does not want to see any more channels
enum dma_state_client {
* typedef dma_cookie_t - an opaque DMA cookie
* if dma_cookie_t is >0 it's a DMA request cookie, <0 it's an error code
typedef s32 dma_cookie_t;
#define dma_submit_error(cookie) ((cookie) < 0 ? 1 : 0)
* enum dma_status - DMA transaction status
* @DMA_SUCCESS: transaction completed successfully
* @DMA_IN_PROGRESS: transaction not yet processed
* @DMA_ERROR: transaction failed
enum dma_status {
* enum dma_transaction_type - DMA transaction types/indexes
enum dma_transaction_type {
/* last transaction type for creation of the capabilities mask */
* enum dma_slave_width - DMA slave register access width.
* @DMA_SLAVE_WIDTH_8BIT: Do 8-bit slave register accesses
* @DMA_SLAVE_WIDTH_16BIT: Do 16-bit slave register accesses
* @DMA_SLAVE_WIDTH_32BIT: Do 32-bit slave register accesses
enum dma_slave_width {
* enum dma_ctrl_flags - DMA flags to augment operation preparation,
* control completion, and communicate status.
* @DMA_PREP_INTERRUPT - trigger an interrupt (callback) upon completion of
* this transaction
* @DMA_CTRL_ACK - the descriptor cannot be reused until the client
* acknowledges receipt, i.e. has has a chance to establish any
* dependency chains
* @DMA_COMPL_SKIP_SRC_UNMAP - set to disable dma-unmapping the source buffer(s)
* @DMA_COMPL_SKIP_DEST_UNMAP - set to disable dma-unmapping the destination(s)
enum dma_ctrl_flags {
DMA_CTRL_ACK = (1 << 1),
* dma_cap_mask_t - capabilities bitmap modeled after cpumask_t.
* See linux/cpumask.h
typedef struct { DECLARE_BITMAP(bits, DMA_TX_TYPE_END); } dma_cap_mask_t;
* struct dma_slave - Information about a DMA slave
* @dev: device acting as DMA slave
* @dma_dev: required DMA master device. If non-NULL, the client can not be
* bound to other masters than this.
* @tx_reg: physical address of data register used for
* memory-to-peripheral transfers
* @rx_reg: physical address of data register used for
* peripheral-to-memory transfers
* @reg_width: peripheral register width
* If dma_dev is non-NULL, the client can not be bound to other DMA
* masters than the one corresponding to this device. The DMA master
* driver may use this to determine if there is controller-specific
* data wrapped around this struct. Drivers of platform code that sets
* the dma_dev field must therefore make sure to use an appropriate
* controller-specific dma slave structure wrapping this struct.
struct dma_slave {
struct device *dev;
struct device *dma_dev;
dma_addr_t tx_reg;
dma_addr_t rx_reg;
enum dma_slave_width reg_width;
* struct dma_chan_percpu - the per-CPU part of struct dma_chan
* @refcount: local_t used for open-coded "bigref" counting
* @memcpy_count: transaction counter
* @bytes_transferred: byte counter
struct dma_chan_percpu {
local_t refcount;
/* stats */
unsigned long memcpy_count;
unsigned long bytes_transferred;
* struct dma_chan - devices supply DMA channels, clients use them
* @device: ptr to the dma device who supplies this channel, always !%NULL
* @cookie: last cookie value returned to client
* @chan_id: channel ID for sysfs
* @class_dev: class device for sysfs
* @refcount: kref, used in "bigref" slow-mode
* @slow_ref: indicates that the DMA channel is free
* @rcu: the DMA channel's RCU head
* @device_node: used to add this to the device chan list
* @local: per-cpu pointer to a struct dma_chan_percpu
* @client-count: how many clients are using this channel
struct dma_chan {
struct dma_device *device;
dma_cookie_t cookie;
/* sysfs */
int chan_id;
struct device dev;
struct kref refcount;
int slow_ref;
struct rcu_head rcu;
struct list_head device_node;
struct dma_chan_percpu *local;
int client_count;
#define to_dma_chan(p) container_of(p, struct dma_chan, dev)
void dma_chan_cleanup(struct kref *kref);
static inline void dma_chan_get(struct dma_chan *chan)
if (unlikely(chan->slow_ref))
else {
local_inc(&(per_cpu_ptr(chan->local, get_cpu())->refcount));
static inline void dma_chan_put(struct dma_chan *chan)
if (unlikely(chan->slow_ref))
kref_put(&chan->refcount, dma_chan_cleanup);
else {
local_dec(&(per_cpu_ptr(chan->local, get_cpu())->refcount));
* typedef dma_event_callback - function pointer to a DMA event callback
* For each channel added to the system this routine is called for each client.
* If the client would like to use the channel it returns '1' to signal (ack)
* the dmaengine core to take out a reference on the channel and its
* corresponding device. A client must not 'ack' an available channel more
* than once. When a channel is removed all clients are notified. If a client
* is using the channel it must 'ack' the removal. A client must not 'ack' a
* removed channel more than once.
* @client - 'this' pointer for the client context
* @chan - channel to be acted upon
* @state - available or removed
struct dma_client;
typedef enum dma_state_client (*dma_event_callback) (struct dma_client *client,
struct dma_chan *chan, enum dma_state state);
* struct dma_client - info on the entity making use of DMA services
* @event_callback: func ptr to call when something happens
* @cap_mask: only return channels that satisfy the requested capabilities
* a value of zero corresponds to any capability
* @slave: data for preparing slave transfer. Must be non-NULL iff the
* DMA_SLAVE capability is requested.
* @global_node: list_head for global dma_client_list
struct dma_client {
dma_event_callback event_callback;
dma_cap_mask_t cap_mask;
struct dma_slave *slave;
struct list_head global_node;
typedef void (*dma_async_tx_callback)(void *dma_async_param);
* struct dma_async_tx_descriptor - async transaction descriptor
* ---dma generic offload fields---
* @cookie: tracking cookie for this transaction, set to -EBUSY if
* this tx is sitting on a dependency list
* @flags: flags to augment operation preparation, control completion, and
* communicate status
* @phys: physical address of the descriptor
* @tx_list: driver common field for operations that require multiple
* descriptors
* @chan: target channel for this operation
* @tx_submit: set the prepared descriptor(s) to be executed by the engine
* @callback: routine to call after this operation is complete
* @callback_param: general parameter to pass to the callback routine
* ---async_tx api specific fields---
* @next: at completion submit this descriptor
* @parent: pointer to the next level up in the dependency chain
* @lock: protect the parent and next pointers
struct dma_async_tx_descriptor {
dma_cookie_t cookie;
enum dma_ctrl_flags flags; /* not a 'long' to pack with cookie */
dma_addr_t phys;
struct list_head tx_list;
struct dma_chan *chan;
dma_cookie_t (*tx_submit)(struct dma_async_tx_descriptor *tx);
dma_async_tx_callback callback;
void *callback_param;
struct dma_async_tx_descriptor *next;
struct dma_async_tx_descriptor *parent;
spinlock_t lock;
* struct dma_device - info on the entity supplying DMA services
* @chancnt: how many DMA channels are supported
* @channels: the list of struct dma_chan
* @global_node: list_head for global dma_device_list
* @cap_mask: one or more dma_capability flags
* @max_xor: maximum number of xor sources, 0 if no capability
* @refcount: reference count
* @done: IO completion struct
* @dev_id: unique device ID
* @dev: struct device reference for dma mapping api
* @device_alloc_chan_resources: allocate resources and return the
* number of allocated descriptors
* @device_free_chan_resources: release DMA channel's resources
* @device_prep_dma_memcpy: prepares a memcpy operation
* @device_prep_dma_xor: prepares a xor operation
* @device_prep_dma_zero_sum: prepares a zero_sum operation
* @device_prep_dma_memset: prepares a memset operation
* @device_prep_dma_interrupt: prepares an end of chain interrupt operation
* @device_prep_slave_sg: prepares a slave dma operation
* @device_terminate_all: terminate all pending operations
* @device_issue_pending: push pending transactions to hardware
struct dma_device {
unsigned int chancnt;
struct list_head channels;
struct list_head global_node;
dma_cap_mask_t cap_mask;
int max_xor;
struct kref refcount;
struct completion done;
int dev_id;
struct device *dev;
int (*device_alloc_chan_resources)(struct dma_chan *chan,
struct dma_client *client);
void (*device_free_chan_resources)(struct dma_chan *chan);
struct dma_async_tx_descriptor *(*device_prep_dma_memcpy)(
struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
size_t len, unsigned long flags);
struct dma_async_tx_descriptor *(*device_prep_dma_xor)(
struct dma_chan *chan, dma_addr_t dest, dma_addr_t *src,
unsigned int src_cnt, size_t len, unsigned long flags);
struct dma_async_tx_descriptor *(*device_prep_dma_zero_sum)(
struct dma_chan *chan, dma_addr_t *src, unsigned int src_cnt,
size_t len, u32 *result, unsigned long flags);
struct dma_async_tx_descriptor *(*device_prep_dma_memset)(
struct dma_chan *chan, dma_addr_t dest, int value, size_t len,
unsigned long flags);
struct dma_async_tx_descriptor *(*device_prep_dma_interrupt)(
struct dma_chan *chan, unsigned long flags);
struct dma_async_tx_descriptor *(*device_prep_slave_sg)(
struct dma_chan *chan, struct scatterlist *sgl,
unsigned int sg_len, enum dma_data_direction direction,
unsigned long flags);
void (*device_terminate_all)(struct dma_chan *chan);
enum dma_status (*device_is_tx_complete)(struct dma_chan *chan,
dma_cookie_t cookie, dma_cookie_t *last,
dma_cookie_t *used);
void (*device_issue_pending)(struct dma_chan *chan);
/* --- public DMA engine API --- */
void dma_async_client_register(struct dma_client *client);
void dma_async_client_unregister(struct dma_client *client);
void dma_async_client_chan_request(struct dma_client *client);
dma_cookie_t dma_async_memcpy_buf_to_buf(struct dma_chan *chan,
void *dest, void *src, size_t len);
dma_cookie_t dma_async_memcpy_buf_to_pg(struct dma_chan *chan,
struct page *page, unsigned int offset, void *kdata, size_t len);
dma_cookie_t dma_async_memcpy_pg_to_pg(struct dma_chan *chan,
struct page *dest_pg, unsigned int dest_off, struct page *src_pg,
unsigned int src_off, size_t len);
void dma_async_tx_descriptor_init(struct dma_async_tx_descriptor *tx,
struct dma_chan *chan);
static inline void async_tx_ack(struct dma_async_tx_descriptor *tx)
tx->flags |= DMA_CTRL_ACK;
static inline bool async_tx_test_ack(struct dma_async_tx_descriptor *tx)
return (tx->flags & DMA_CTRL_ACK) == DMA_CTRL_ACK;
#define first_dma_cap(mask) __first_dma_cap(&(mask))
static inline int __first_dma_cap(const dma_cap_mask_t *srcp)
return min_t(int, DMA_TX_TYPE_END,
find_first_bit(srcp->bits, DMA_TX_TYPE_END));
#define next_dma_cap(n, mask) __next_dma_cap((n), &(mask))
static inline int __next_dma_cap(int n, const dma_cap_mask_t *srcp)
return min_t(int, DMA_TX_TYPE_END,
find_next_bit(srcp->bits, DMA_TX_TYPE_END, n+1));
#define dma_cap_set(tx, mask) __dma_cap_set((tx), &(mask))
static inline void
__dma_cap_set(enum dma_transaction_type tx_type, dma_cap_mask_t *dstp)
set_bit(tx_type, dstp->bits);
#define dma_has_cap(tx, mask) __dma_has_cap((tx), &(mask))
static inline int
__dma_has_cap(enum dma_transaction_type tx_type, dma_cap_mask_t *srcp)
return test_bit(tx_type, srcp->bits);
#define for_each_dma_cap_mask(cap, mask) \
for ((cap) = first_dma_cap(mask); \
(cap) < DMA_TX_TYPE_END; \
(cap) = next_dma_cap((cap), (mask)))
* dma_async_issue_pending - flush pending transactions to HW
* @chan: target DMA channel
* This allows drivers to push copies to HW in batches,
* reducing MMIO writes where possible.
static inline void dma_async_issue_pending(struct dma_chan *chan)
#define dma_async_memcpy_issue_pending(chan) dma_async_issue_pending(chan)
* dma_async_is_tx_complete - poll for transaction completion
* @chan: DMA channel
* @cookie: transaction identifier to check status of
* @last: returns last completed cookie, can be NULL
* @used: returns last issued cookie, can be NULL
* If @last and @used are passed in, upon return they reflect the driver
* internal state and can be used with dma_async_is_complete() to check
* the status of multiple cookies without re-checking hardware state.
static inline enum dma_status dma_async_is_tx_complete(struct dma_chan *chan,
dma_cookie_t cookie, dma_cookie_t *last, dma_cookie_t *used)
return chan->device->device_is_tx_complete(chan, cookie, last, used);
#define dma_async_memcpy_complete(chan, cookie, last, used)\
dma_async_is_tx_complete(chan, cookie, last, used)
* dma_async_is_complete - test a cookie against chan state
* @cookie: transaction identifier to test status of
* @last_complete: last know completed transaction
* @last_used: last cookie value handed out
* dma_async_is_complete() is used in dma_async_memcpy_complete()
* the test logic is separated for lightweight testing of multiple cookies
static inline enum dma_status dma_async_is_complete(dma_cookie_t cookie,
dma_cookie_t last_complete, dma_cookie_t last_used)
if (last_complete <= last_used) {
if ((cookie <= last_complete) || (cookie > last_used))
} else {
if ((cookie <= last_complete) && (cookie > last_used))
enum dma_status dma_sync_wait(struct dma_chan *chan, dma_cookie_t cookie);
/* --- DMA device --- */
int dma_async_device_register(struct dma_device *device);
void dma_async_device_unregister(struct dma_device *device);
/* --- Helper iov-locking functions --- */
struct dma_page_list {
char __user *base_address;
int nr_pages;
struct page **pages;
struct dma_pinned_list {
int nr_iovecs;
struct dma_page_list page_list[0];
struct dma_pinned_list *dma_pin_iovec_pages(struct iovec *iov, size_t len);
void dma_unpin_iovec_pages(struct dma_pinned_list* pinned_list);
dma_cookie_t dma_memcpy_to_iovec(struct dma_chan *chan, struct iovec *iov,
struct dma_pinned_list *pinned_list, unsigned char *kdata, size_t len);
dma_cookie_t dma_memcpy_pg_to_iovec(struct dma_chan *chan, struct iovec *iov,
struct dma_pinned_list *pinned_list, struct page *page,
unsigned int offset, size_t len);
#endif /* DMAENGINE_H */