1. dma_chan : --- dma channel 的意思
/**
* 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
* @dev: class device for sysfs
* @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
* @table_count: number of appearances in the mem-to-mem allocation table
* @private: private data for certain client-channel associations
*/
struct dma_chan {
struct dma_device *device;
dma_cookie_t cookie;
/* sysfs */
int chan_id;
struct dma_chan_dev *dev;
struct list_head device_node;
struct dma_chan_percpu __percpu *local;
int client_count;
int table_count;
void *private;
};
2. dma_chan_dev -- sysfs 相关
/**
* struct dma_chan_dev - relate sysfs device node to backing channel device
* @chan - driver channel device
* @device - sysfs device
* @dev_id - parent dma_device dev_id
* @idr_ref - reference count to gate release of dma_device dev_id
*/
struct dma_chan_dev {
struct dma_chan *chan;
struct device device;
int dev_id;
atomic_t *idr_ref;
};
3. dmatest_chan ---dma测试使用的channel
struct dmatest_chan {
struct list_head node;
struct dma_chan *chan;
struct list_head threads;
};
4. dmatest_thread --- dmatest 的线程
struct dmatest_thread {
struct list_head node;
struct task_struct *task;
struct dma_chan *chan;
u8 **srcs;
u8 **dsts;
enum dma_transaction_type type;
};
5. dma_device --- dma类型设备
/**
* struct dma_device - info on the entity supplying DMA services
* @chancnt: how many DMA channels are supported
* @privatecnt: how many DMA channels are requested by dma_request_channel
* @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
* @max_pq: maximum number of PQ sources and PQ-continue capability
* @copy_align: alignment shift for memcpy operations
* @xor_align: alignment shift for xor operations
* @pq_align: alignment shift for pq operations
* @fill_align: alignment shift for memset operations
* @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_xor_val: prepares a xor validation operation
* @device_prep_dma_pq: prepares a pq operation
* @device_prep_dma_pq_val: prepares a pqzero_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_is_tx_complete: poll for transaction completion
* @device_issue_pending: push pending transactions to hardware
*/
struct dma_device {
unsigned int chancnt;
unsigned int privatecnt;
struct list_head channels;
struct list_head global_node;
dma_cap_mask_t cap_mask;
unsigned short max_xor;
unsigned short max_pq;
u8 copy_align;
u8 xor_align;
u8 pq_align;
u8 fill_align;
#define DMA_HAS_PQ_CONTINUE (1 << 15)
int dev_id;
struct device *dev;
int (*device_alloc_chan_resources)(struct dma_chan *chan);
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_xor_val)(
struct dma_chan *chan, dma_addr_t *src, unsigned int src_cnt,
size_t len, enum sum_check_flags *result, unsigned long flags);
struct dma_async_tx_descriptor *(*device_prep_dma_pq)(
struct dma_chan *chan, dma_addr_t *dst, dma_addr_t *src,
unsigned int src_cnt, const unsigned char *scf,
size_t len, unsigned long flags);
struct dma_async_tx_descriptor *(*device_prep_dma_pq_val)(
struct dma_chan *chan, dma_addr_t *pq, dma_addr_t *src,
unsigned int src_cnt, const unsigned char *scf, size_t len,
enum sum_check_flags *pqres, 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);
};
6. dma_transaction_type --- dma 传输方式:
/**
* enum dma_transaction_type - DMA transaction types/indexes
*
* Note: The DMA_ASYNC_TX capability is not to be set by drivers. It is
* automatically set as dma devices are registered.
*/
enum dma_transaction_type {
DMA_MEMCPY,
DMA_XOR,
DMA_PQ,
DMA_XOR_VAL,
DMA_PQ_VAL,
DMA_MEMSET,
DMA_INTERRUPT,
DMA_PRIVATE,
DMA_ASYNC_TX,
DMA_SLAVE,
};
7. dma_status --- DMA 传输状态
/**
* 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 {
DMA_SUCCESS,
DMA_IN_PROGRESS,
DMA_ERROR,
};
8. dma_ctrl_flags --- DMA 传输控制标志
/**
* 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 - if clear, 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)
* @DMA_COMPL_SRC_UNMAP_SINGLE - set to do the source dma-unmapping as single
* (if not set, do the source dma-unmapping as page)
* @DMA_COMPL_DEST_UNMAP_SINGLE - set to do the destination dma-unmapping as single
* (if not set, do the destination dma-unmapping as page)
* @DMA_PREP_PQ_DISABLE_P - prevent generation of P while generating Q
* @DMA_PREP_PQ_DISABLE_Q - prevent generation of Q while generating P
* @DMA_PREP_CONTINUE - indicate to a driver that it is reusing buffers as
* sources that were the result of a previous operation, in the case of a PQ
* operation it continues the calculation with new sources
* @DMA_PREP_FENCE - tell the driver that subsequent operations depend
* on the result of this operation
*/
enum dma_ctrl_flags {
DMA_PREP_INTERRUPT = (1 << 0),
DMA_CTRL_ACK = (1 << 1),
DMA_COMPL_SKIP_SRC_UNMAP = (1 << 2),
DMA_COMPL_SKIP_DEST_UNMAP = (1 << 3),
DMA_COMPL_SRC_UNMAP_SINGLE = (1 << 4),
DMA_COMPL_DEST_UNMAP_SINGLE = (1 << 5),
DMA_PREP_PQ_DISABLE_P = (1 << 6),
DMA_PREP_PQ_DISABLE_Q = (1 << 7),
DMA_PREP_CONTINUE = (1 << 8),
DMA_PREP_FENCE = (1 << 9),
};