diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/dmaengine.h | 86 |
1 files changed, 86 insertions, 0 deletions
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index defa377d2ef5..6fe46c0c9452 100644 --- a/include/linux/dmaengine.h +++ b/include/linux/dmaengine.h @@ -322,6 +322,8 @@ struct dma_router { * @slave: ptr to the device using this channel * @cookie: last cookie value returned to client * @completed_cookie: last completed cookie for this channel + * @lock: protect between config and prepare transfer when driver have not + * implemented callback device_prep_config_sg(). * @chan_id: channel ID for sysfs * @dev: class device for sysfs * @name: backlink name for sysfs @@ -341,6 +343,12 @@ struct dma_chan { dma_cookie_t cookie; dma_cookie_t completed_cookie; + /* + * protect between config and prepare transfer because *_prep() may be + * called from complete callback, which is in GFP_NOSLEEP context. + */ + spinlock_t lock; + /* sysfs */ int chan_id; struct dma_chan_dev *dev; @@ -1068,6 +1076,84 @@ dmaengine_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl, return dmaengine_prep_config_sg(chan, sgl, sg_len, dir, flags, NULL); } +/** + * dmaengine_prep_config_sg_safe - prepare a scatter-gather DMA transfer + * with atomic slave configuration update + * @chan: DMA channel + * @sgl: scatterlist for the transfer + * @sg_len: number of entries in @sgl + * @dir: DMA transfer direction + * @flags: transfer preparation flags + * @config: DMA slave configuration for this transfer + * + * Prepare a DMA scatter-gather transfer together with a corresponding slave + * configuration update in a re-entrant and race-safe manner. + * + * DMA engine drivers may implement the optional + * device_prep_config_sg() callback to perform both the slave configuration + * and descriptor preparation atomically. In this case, the operation is + * fully handled by the DMA engine driver. + * + * If the DMA engine driver does not implement device_prep_config_sg(), falls + * back to calling dmaengine_slave_config() followed by dmaengine_prep_slave_sg(). + * The fallback path is protected by a per-channel spinlock to ensure that + * concurrent callers cannot interleave configuration and descriptor preparation + * on the same DMA channel. + * + * Return: Pointer to a prepared DMA async transaction descriptor on success, + * or %NULL if the transfer could not be prepared. + */ +static inline struct dma_async_tx_descriptor * +dmaengine_prep_config_sg_safe(struct dma_chan *chan, struct scatterlist *sgl, + unsigned int sg_len, + enum dma_transfer_direction dir, + unsigned long flags, + struct dma_slave_config *config) +{ + struct dma_async_tx_descriptor *tx; + unsigned long spinlock_flags; + + if (!chan || !chan->device) + return NULL; + + if (!chan->device->device_prep_config_sg) + spin_lock_irqsave(&chan->lock, spinlock_flags); + + tx = dmaengine_prep_config_sg(chan, sgl, sg_len, dir, flags, config); + + if (!chan->device->device_prep_config_sg) + spin_unlock_irqrestore(&chan->lock, spinlock_flags); + + return tx; +} + +/** + * dmaengine_prep_config_single_safe - prepare a single-buffer DMA transfer + * with atomic slave configuration update + * @chan: DMA channel + * @buf: DMA buffer address + * @len: length of the transfer in bytes + * @dir: DMA transfer direction + * @flags: transfer preparation flags + * @config: DMA slave configuration for this transfer + * + * Detail see dmaengine_prep_config_sg_safe(). + */ +static inline struct dma_async_tx_descriptor * +dmaengine_prep_config_single_safe(struct dma_chan *chan, dma_addr_t buf, + size_t len, enum dma_transfer_direction dir, + unsigned long flags, + struct dma_slave_config *config) +{ + struct scatterlist sg; + + sg_init_table(&sg, 1); + sg_dma_address(&sg) = buf; + sg_dma_len(&sg) = len; + + return dmaengine_prep_config_sg_safe(chan, &sg, 1, dir, flags, config); +} + #ifdef CONFIG_RAPIDIO_DMA_ENGINE struct rio_dma_ext; static inline struct dma_async_tx_descriptor *dmaengine_prep_rio_sg( |