From: Martin Sperl <kernel@xxxxxxxxxxxxxxxx> In preparation of adding slave_sg functionality this patch moves the generation/allocation of bcm2835_desc and the building of the corresponding DMA-control-block chain from bcm2835_dma_prep_dma_cyclic into the newly created method bcm2835_dma_create_cb_chain. Signed-off-by: Martin Sperl <kernel@xxxxxxxxxxxxxxxx> Reviewed-by: Eric Anholt <eric@xxxxxxxxxx> Signed-off-by: Eric Anholt <eric@xxxxxxxxxx> --- drivers/dma/bcm2835-dma.c | 294 +++++++++++++++++++++++++++++++--------------- 1 file changed, 198 insertions(+), 96 deletions(-) diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c index b3bc382..4db0e23 100644 --- a/drivers/dma/bcm2835-dma.c +++ b/drivers/dma/bcm2835-dma.c @@ -88,12 +88,12 @@ struct bcm2835_desc { struct virt_dma_desc vd; enum dma_transfer_direction dir; - struct bcm2835_cb_entry *cb_list; - unsigned int frames; size_t size; bool cyclic; + + struct bcm2835_cb_entry cb_list[]; }; #define BCM2835_DMA_CS 0x00 @@ -169,6 +169,13 @@ struct bcm2835_desc { #define BCM2835_DMA_CHAN(n) ((n) << 8) /* Base address */ #define BCM2835_DMA_CHANIO(base, n) ((base) + BCM2835_DMA_CHAN(n)) +/* how many frames of max_len size do we need to transfer len bytes */ +static inline size_t bcm2835_dma_frames_for_length(size_t len, + size_t max_len) +{ + return DIV_ROUND_UP(len, max_len); +} + static inline struct bcm2835_dmadev *to_bcm2835_dma_dev(struct dma_device *d) { return container_of(d, struct bcm2835_dmadev, ddev); @@ -185,19 +192,161 @@ static inline struct bcm2835_desc *to_bcm2835_dma_desc( return container_of(t, struct bcm2835_desc, vd.tx); } -static void bcm2835_dma_desc_free(struct virt_dma_desc *vd) +static void bcm2835_dma_free_cb_chain(struct bcm2835_desc *desc) { - struct bcm2835_desc *desc = container_of(vd, struct bcm2835_desc, vd); - int i; + size_t i; for (i = 0; i < desc->frames; i++) dma_pool_free(desc->c->cb_pool, desc->cb_list[i].cb, desc->cb_list[i].paddr); - kfree(desc->cb_list); kfree(desc); } +static void bcm2835_dma_desc_free(struct virt_dma_desc *vd) +{ + bcm2835_dma_free_cb_chain( + container_of(vd, struct bcm2835_desc, vd)); +} + +static void bcm2835_dma_create_cb_set_length( + struct bcm2835_chan *chan, + struct bcm2835_dma_cb *control_block, + size_t len, + size_t period_len, + size_t *total_len, + u32 finalextrainfo) +{ + /* set the length */ + control_block->length = len; + + /* finished if we have no period_length */ + if (!period_len) + return; + + /* + * period_len means: that we need to generate + * transfers that are terminating at every + * multiple of period_len - this is typically + * used to set the interrupt flag in info + * which is required during cyclic transfers + */ + + /* have we filled in period_length yet? */ + if (*total_len + control_block->length < period_len) + return; + + /* calculate the length that remains to reach period_length */ + control_block->length = period_len - *total_len; + + /* reset total_length for next period */ + *total_len = 0; + + /* add extrainfo bits in info */ + control_block->info |= finalextrainfo; +} + +/** + * bcm2835_dma_create_cb_chain - create a control block and fills data in + * + * @chan: the @dma_chan for which we run this + * @direction: the direction in which we transfer + * @cyclic: it is a cyclic transfer + * @info: the default info bits to apply per controlblock + * @frames: number of controlblocks to allocate + * @src: the src address to assign (if the S_INC bit is set + * in @info, then it gets incremented) + * @dst: the dst address to assign (if the D_INC bit is set + * in @info, then it gets incremented) + * @buf_len: the full buffer length (may also be 0) + * @period_len: the period length when to apply @finalextrainfo + * in addition to the last transfer + * this will also break some control-blocks early + * @finalextrainfo: additional bits in last controlblock + * (or when period_len is reached in case of cyclic) + * @gfp: the GFP flag to use for allocation + */ +static struct bcm2835_desc *bcm2835_dma_create_cb_chain( + struct dma_chan *chan, enum dma_transfer_direction direction, + bool cyclic, u32 info, u32 finalextrainfo, size_t frames, + dma_addr_t src, dma_addr_t dst, size_t buf_len, + size_t period_len, gfp_t gfp) +{ + struct bcm2835_chan *c = to_bcm2835_dma_chan(chan); + size_t len = buf_len, total_len; + size_t frame; + struct bcm2835_desc *d; + struct bcm2835_cb_entry *cb_entry; + struct bcm2835_dma_cb *control_block; + + /* allocate and setup the descriptor. */ + d = kzalloc(sizeof(*d) + frames * sizeof(struct bcm2835_cb_entry), + gfp); + if (!d) + return NULL; + + d->c = c; + d->dir = direction; + d->cyclic = cyclic; + + /* + * Iterate over all frames, create a control block + * for each frame and link them together. + */ + for (frame = 0, total_len = 0; frame < frames; d->frames++, frame++) { + cb_entry = &d->cb_list[frame]; + cb_entry->cb = dma_pool_alloc(c->cb_pool, gfp, + &cb_entry->paddr); + if (!cb_entry->cb) + goto error_cb; + + /* fill in the control block */ + control_block = cb_entry->cb; + control_block->info = info; + control_block->src = src; + control_block->dst = dst; + control_block->stride = 0; + control_block->next = 0; + /* set up length in control_block if requested */ + if (buf_len) { + /* calculate length honoring period_length */ + bcm2835_dma_create_cb_set_length( + c, control_block, + len, period_len, &total_len, + cyclic ? finalextrainfo : 0); + + /* calculate new remaining length */ + len -= control_block->length; + } + + /* link this the last controlblock */ + if (frame) + d->cb_list[frame - 1].cb->next = cb_entry->paddr; + + /* update src and dst and length */ + if (src && (info & BCM2835_DMA_S_INC)) + src += control_block->length; + if (dst && (info & BCM2835_DMA_D_INC)) + dst += control_block->length; + + /* Length of total transfer */ + d->size += control_block->length; + } + + /* the last frame requires extra flags */ + d->cb_list[d->frames - 1].cb->info |= finalextrainfo; + + /* detect a size missmatch */ + if (buf_len && (d->size != buf_len)) + goto error_cb; + + return d; +error_cb: + bcm2835_dma_free_cb_chain(d); + + return NULL; +} + static int bcm2835_dma_abort(void __iomem *chan_base) { unsigned long cs; @@ -391,12 +540,11 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic( unsigned long flags) { struct bcm2835_chan *c = to_bcm2835_dma_chan(chan); - enum dma_slave_buswidth dev_width; struct bcm2835_desc *d; - dma_addr_t dev_addr; - unsigned int es, sync_type; - unsigned int frame; - int i; + dma_addr_t src, dst; + u32 info = BCM2835_DMA_WAIT_RESP; + u32 extra = BCM2835_DMA_INT_EN; + size_t frames; /* Grab configuration */ if (!is_slave_direction(direction)) { @@ -404,104 +552,58 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic( return NULL; } - if (direction == DMA_DEV_TO_MEM) { - dev_addr = c->cfg.src_addr; - dev_width = c->cfg.src_addr_width; - sync_type = BCM2835_DMA_S_DREQ; - } else { - dev_addr = c->cfg.dst_addr; - dev_width = c->cfg.dst_addr_width; - sync_type = BCM2835_DMA_D_DREQ; - } - - /* Bus width translates to the element size (ES) */ - switch (dev_width) { - case DMA_SLAVE_BUSWIDTH_4_BYTES: - es = BCM2835_DMA_DATA_TYPE_S32; - break; - default: + if (!buf_len) { + dev_err(chan->device->dev, + "%s: bad buffer length (= 0)\n", __func__); return NULL; } - /* Now allocate and setup the descriptor. */ - d = kzalloc(sizeof(*d), GFP_NOWAIT); - if (!d) - return NULL; + /* + * warn if buf_len is not a multiple of period_len - this may leed + * to unexpected latencies for interrupts and thus audiable clicks + */ + if (buf_len % period_len) + dev_warn_once(chan->device->dev, + "%s: buffer_length (%zd) is not a multiple of period_len (%zd)\n", + __func__, buf_len, period_len); - d->c = c; - d->dir = direction; - d->frames = buf_len / period_len; - d->cyclic = true; + /* Setup DREQ channel */ + if (c->dreq != 0) + info |= BCM2835_DMA_PER_MAP(c->dreq); - d->cb_list = kcalloc(d->frames, sizeof(*d->cb_list), GFP_KERNEL); - if (!d->cb_list) { - kfree(d); - return NULL; + if (direction == DMA_DEV_TO_MEM) { + if (c->cfg.src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES) + return NULL; + src = c->cfg.src_addr; + dst = buf_addr; + info |= BCM2835_DMA_S_DREQ | BCM2835_DMA_D_INC; + } else { + if (c->cfg.dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES) + return NULL; + dst = c->cfg.dst_addr; + src = buf_addr; + info |= BCM2835_DMA_D_DREQ | BCM2835_DMA_S_INC; } - /* Allocate memory for control blocks */ - for (i = 0; i < d->frames; i++) { - struct bcm2835_cb_entry *cb_entry = &d->cb_list[i]; - cb_entry->cb = dma_pool_zalloc(c->cb_pool, GFP_ATOMIC, - &cb_entry->paddr); - if (!cb_entry->cb) - goto error_cb; - } + /* calculate number of frames */ + frames = DIV_ROUND_UP(buf_len, period_len); /* - * Iterate over all frames, create a control block - * for each frame and link them together. + * allocate the CB chain + * note that we need to use GFP_NOWAIT, as the ALSA i2s dmaengine + * implementation calls prep_dma_cyclic with interrupts disabled. */ - for (frame = 0; frame < d->frames; frame++) { - struct bcm2835_dma_cb *control_block = d->cb_list[frame].cb; - - /* Setup adresses */ - if (d->dir == DMA_DEV_TO_MEM) { - control_block->info = BCM2835_DMA_D_INC; - control_block->src = dev_addr; - control_block->dst = buf_addr + frame * period_len; - } else { - control_block->info = BCM2835_DMA_S_INC; - control_block->src = buf_addr + frame * period_len; - control_block->dst = dev_addr; - } - - /* Enable interrupt */ - control_block->info |= BCM2835_DMA_INT_EN; - - /* Setup synchronization */ - if (sync_type != 0) - control_block->info |= sync_type; - - /* Setup DREQ channel */ - if (c->dreq != 0) - control_block->info |= - BCM2835_DMA_PER_MAP(c->dreq); - - /* Length of a frame */ - control_block->length = period_len; - d->size += control_block->length; + d = bcm2835_dma_create_cb_chain(chan, direction, true, + info, extra, + frames, src, dst, buf_len, + period_len, GFP_NOWAIT); + if (!d) + return NULL; - /* - * Next block is the next frame. - * This DMA engine driver currently only supports cyclic DMA. - * Therefore, wrap around at number of frames. - */ - control_block->next = d->cb_list[((frame + 1) % d->frames)].paddr; - } + /* wrap around into a loop */ + d->cb_list[d->frames - 1].cb->next = d->cb_list[0].paddr; return vchan_tx_prep(&c->vc, &d->vd, flags); -error_cb: - i--; - for (; i >= 0; i--) { - struct bcm2835_cb_entry *cb_entry = &d->cb_list[i]; - - dma_pool_free(c->cb_pool, cb_entry->cb, cb_entry->paddr); - } - - kfree(d->cb_list); - kfree(d); - return NULL; } static int bcm2835_dma_slave_config(struct dma_chan *chan, -- 2.7.0 -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html