diff options
| -rw-r--r-- | drivers/dma/amba-pl08x.c | 61 | ||||
| -rw-r--r-- | include/linux/amba/pl08x.h | 4 |
2 files changed, 57 insertions, 8 deletions
diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c index f70aa574c58f..a59c3c47286c 100644 --- a/drivers/dma/amba-pl08x.c +++ b/drivers/dma/amba-pl08x.c @@ -66,11 +66,6 @@ * after the final transfer signalled by LBREQ or LSREQ. The DMAC * will then move to the next LLI entry. * - * Only the former works sanely with scatter lists, so we only implement - * the DMAC flow control method. However, peripherals which use the LBREQ - * and LSREQ signals (eg, MMCI) are unable to use this mode, which through - * these hardware restrictions prevents them from using scatter DMA. - * * Global TODO: * - Break out common code from arch/arm/mach-s3c64xx and share */ @@ -618,6 +613,49 @@ static int pl08x_fill_llis_for_desc(struct pl08x_driver_data *pl08x, sbus == &bd.srcbus ? "src" : "dst"); /* + * Zero length is only allowed if all these requirements are met: + * - flow controller is peripheral. + * - src.addr is aligned to src.width + * - dst.addr is aligned to dst.width + * + * sg_len == 1 should be true, as there can be two cases here: + * - Memory addresses are contiguous and are not scattered. Here, Only + * one sg will be passed by user driver, with memory address and zero + * length. We pass this to controller and after the transfer it will + * receive the last burst request from peripheral and so transfer + * finishes. + * + * - Memory addresses are scattered and are not contiguous. Here, + * Obviously as DMA controller doesn't know when a lli's transfer gets + * over, it can't load next lli. So in this case, there has to be an + * assumption that only one lli is supported. Thus, we can't have + * scattered addresses. + */ + if (!bd.remainder) { + u32 fc = (txd->ccfg & PL080_CONFIG_FLOW_CONTROL_MASK) >> + PL080_CONFIG_FLOW_CONTROL_SHIFT; + if (!((fc >= PL080_FLOW_SRC2DST_DST) && + (fc <= PL080_FLOW_SRC2DST_SRC))) { + dev_err(&pl08x->adev->dev, "%s sg len can't be zero", + __func__); + return 0; + } + + if ((bd.srcbus.addr % bd.srcbus.buswidth) || + (bd.srcbus.addr % bd.srcbus.buswidth)) { + dev_err(&pl08x->adev->dev, + "%s src & dst address must be aligned to src" + " & dst width if peripheral is flow controller", + __func__); + return 0; + } + + cctl = pl08x_cctl_bits(cctl, bd.srcbus.buswidth, + bd.dstbus.buswidth, 0); + pl08x_fill_lli_for_desc(&bd, num_llis++, 0, cctl); + } + + /* * Send byte by byte for following cases * - Less than a bus width available * - until master bus is aligned @@ -1250,7 +1288,7 @@ static struct dma_async_tx_descriptor *pl08x_prep_slave_sg( struct pl08x_dma_chan *plchan = to_pl08x_chan(chan); struct pl08x_driver_data *pl08x = plchan->host; struct pl08x_txd *txd; - int ret; + int ret, tmp; /* * Current implementation ASSUMES only one sg @@ -1284,12 +1322,10 @@ static struct dma_async_tx_descriptor *pl08x_prep_slave_sg( txd->len = sgl->length; if (direction == DMA_TO_DEVICE) { - txd->ccfg |= PL080_FLOW_MEM2PER << PL080_CONFIG_FLOW_CONTROL_SHIFT; txd->cctl = plchan->dst_cctl; txd->src_addr = sgl->dma_address; txd->dst_addr = plchan->dst_addr; } else if (direction == DMA_FROM_DEVICE) { - txd->ccfg |= PL080_FLOW_PER2MEM << PL080_CONFIG_FLOW_CONTROL_SHIFT; txd->cctl = plchan->src_cctl; txd->src_addr = plchan->src_addr; txd->dst_addr = sgl->dma_address; @@ -1299,6 +1335,15 @@ static struct dma_async_tx_descriptor *pl08x_prep_slave_sg( return NULL; } + if (plchan->cd->device_fc) + tmp = (direction == DMA_TO_DEVICE) ? PL080_FLOW_MEM2PER_PER : + PL080_FLOW_PER2MEM_PER; + else + tmp = (direction == DMA_TO_DEVICE) ? PL080_FLOW_MEM2PER : + PL080_FLOW_PER2MEM; + + txd->ccfg |= tmp << PL080_CONFIG_FLOW_CONTROL_SHIFT; + ret = pl08x_prep_channel_resources(plchan, txd); if (ret) return NULL; diff --git a/include/linux/amba/pl08x.h b/include/linux/amba/pl08x.h index ecd17f581e71..a22662c93981 100644 --- a/include/linux/amba/pl08x.h +++ b/include/linux/amba/pl08x.h @@ -47,6 +47,9 @@ enum { * @muxval: a number usually used to poke into some mux regiser to * mux in the signal to this channel * @cctl_opt: default options for the channel control register + * @device_fc: Flow Controller Settings for ccfg register. Only valid for slave + * channels. Fill with 'true' if peripheral should be flow controller. Direction + * will be selected at Runtime. * @addr: source/target address in physical memory for this DMA channel, * can be the address of a FIFO register for burst requests for example. * This can be left undefined if the PrimeCell API is used for configuring @@ -65,6 +68,7 @@ struct pl08x_channel_data { int max_signal; u32 muxval; u32 cctl; + bool device_fc; dma_addr_t addr; bool circular_buffer; bool single; |