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Message-ID: <20140120074019.GF26823@intel.com>
Date: Mon, 20 Jan 2014 13:10:19 +0530
From: Vinod Koul <vinod.koul@...el.com>
To: Jingchang Lu <b35083@...escale.com>
Cc: dan.j.williams@...el.com, arnd@...db.de, shawn.guo@...aro.org,
pawel.moll@....com, mark.rutland@....com, swarren@...dotorg.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
devicetree@...r.kernel.org, Alison Wang <b18965@...escale.com>
Subject: Re: [PATCHv10 2/2] dma: Add Freescale eDMA engine driver support
On Fri, Jan 17, 2014 at 02:04:44PM +0800, Jingchang Lu wrote:
> Add Freescale enhanced direct memory(eDMA) controller support.
> This module can be found on Vybrid and LS-1 SoCs.
>
> Signed-off-by: Alison Wang <b18965@...escale.com>
> Signed-off-by: Jingchang Lu <b35083@...escale.com>
> Acked-by: Arnd Bergmann <arnd@...db.de>
> ---
> +struct fsl_edma_sw_tcd {
> + dma_addr_t ptcd;
> + struct fsl_edma_hw_tcd *vtcd;
> +};
> +
> +struct fsl_edma_slave_config {
> + enum dma_transfer_direction dir;
> + enum dma_slave_buswidth addr_width;
> + u32 dev_addr;
u32 for device address doesnt look right, we should be using dma_addr_t?
> + u32 burst;
> + u32 attr;
Looking at this, all fields expect attr are in dma_slave_config! So why do we
need these here and what does the attr mean?
> +static int fsl_edma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
> + unsigned long arg)
> +{
> + struct fsl_edma_chan *fsl_chan = to_fsl_edma_chan(chan);
> + struct dma_slave_config *cfg = (void *)arg;
> + unsigned long flags;
> + LIST_HEAD(head);
> +
> + switch (cmd) {
> + case DMA_TERMINATE_ALL:
> + spin_lock_irqsave(&fsl_chan->vchan.lock, flags);
> + fsl_edma_disable_request(fsl_chan);
> + fsl_chan->edesc = NULL;
> + vchan_get_all_descriptors(&fsl_chan->vchan, &head);
> + spin_unlock_irqrestore(&fsl_chan->vchan.lock, flags);
> + vchan_dma_desc_free_list(&fsl_chan->vchan, &head);
> + return 0;
well what happens to the current ongoing transactions, i don't see those getting
terminated?
> +
> + case DMA_SLAVE_CONFIG:
> + fsl_chan->fsc.dir = cfg->direction;
> + if (cfg->direction == DMA_DEV_TO_MEM) {
> + fsl_chan->fsc.dev_addr = cfg->src_addr;
> + fsl_chan->fsc.addr_width = cfg->src_addr_width;
> + fsl_chan->fsc.burst = cfg->src_maxburst;
> + fsl_chan->fsc.attr = fsl_edma_get_tcd_attr(cfg->src_addr_width);
> + } else if (cfg->direction == DMA_MEM_TO_DEV) {
> + fsl_chan->fsc.dev_addr = cfg->dst_addr;
> + fsl_chan->fsc.addr_width = cfg->dst_addr_width;
> + fsl_chan->fsc.burst = cfg->dst_maxburst;
> + fsl_chan->fsc.attr = fsl_edma_get_tcd_attr(cfg->dst_addr_width);
okay atrr is address width, why not save this standard struct instead?
> + } else {
> + return -EINVAL;
> + }
> + return 0;
> +
> + case DMA_PAUSE:
> + spin_lock_irqsave(&fsl_chan->vchan.lock, flags);
> + if (fsl_chan->edesc) {
> + fsl_edma_disable_request(fsl_chan);
> + fsl_chan->status = DMA_PAUSED;
> + }
> + spin_unlock_irqrestore(&fsl_chan->vchan.lock, flags);
> + return 0;
> +
> + case DMA_RESUME:
> + spin_lock_irqsave(&fsl_chan->vchan.lock, flags);
> + if (fsl_chan->edesc) {
> + fsl_edma_enable_request(fsl_chan);
> + fsl_chan->status = DMA_IN_PROGRESS;
> + }
> + spin_unlock_irqrestore(&fsl_chan->vchan.lock, flags);
> + return 0;
> +
> + default:
> + return -ENXIO;
> + }
> +}
> +
> +static struct fsl_edma_desc *fsl_edma_alloc_desc(struct fsl_edma_chan *fsl_chan,
> + int sg_len)
> +{
> + struct fsl_edma_desc *fsl_desc;
> + int i;
> +
> + fsl_desc = kzalloc(sizeof(*fsl_desc) + sizeof(struct fsl_edma_sw_tcd) * sg_len,
> + GFP_NOWAIT);
> + if (!fsl_desc)
> + return NULL;
> +
> + fsl_desc->echan = fsl_chan;
> + fsl_desc->n_tcds = sg_len;
> + for (i = 0; i < sg_len; i++) {
> + fsl_desc->tcd[i].vtcd = dma_pool_alloc(fsl_chan->tcd_pool,
> + GFP_NOWAIT, &fsl_desc->tcd[i].ptcd);
> + if (!fsl_desc->tcd[i].vtcd)
> + goto err;
> + }
> + return fsl_desc;
> +
> +err:
> + while (--i >= 0)
> + dma_pool_free(fsl_chan->tcd_pool, fsl_desc->tcd[i].vtcd,
> + fsl_desc->tcd[i].ptcd);
> + kfree(fsl_desc);
> + return NULL;
> +}
> +
> +static struct dma_async_tx_descriptor *fsl_edma_prep_dma_cyclic(
> + struct dma_chan *chan, dma_addr_t dma_addr, size_t buf_len,
> + size_t period_len, enum dma_transfer_direction direction,
> + unsigned long flags, void *context)
> +{
you may want to implement the capablities api subsequently for audio usage.
> + struct fsl_edma_chan *fsl_chan = to_fsl_edma_chan(chan);
> + struct fsl_edma_desc *fsl_desc;
> + dma_addr_t dma_buf_next;
> + int sg_len, i;
> + u32 src_addr, dst_addr, last_sg, nbytes;
> + u16 soff, doff, iter;
> +
> + if (!is_slave_direction(fsl_chan->fsc.dir))
> + return NULL;
> +
> + sg_len = buf_len / period_len;
> + fsl_desc = fsl_edma_alloc_desc(fsl_chan, sg_len);
> + if (!fsl_desc)
> + return NULL;
> + fsl_desc->iscyclic = true;
> +
> + dma_buf_next = dma_addr;
> + nbytes = fsl_chan->fsc.addr_width * fsl_chan->fsc.burst;
> + iter = period_len / nbytes;
empty line here pls
> + for (i = 0; i < sg_len; i++) {
> + if (dma_buf_next >= dma_addr + buf_len)
> + dma_buf_next = dma_addr;
> +
> + /* get next sg's physical address */
> + last_sg = fsl_desc->tcd[(i + 1) % sg_len].ptcd;
> +
> + if (fsl_chan->fsc.dir == DMA_MEM_TO_DEV) {
> + src_addr = dma_buf_next;
> + dst_addr = fsl_chan->fsc.dev_addr;
> + soff = fsl_chan->fsc.addr_width;
> + doff = 0;
> + } else {
> + src_addr = fsl_chan->fsc.dev_addr;
> + dst_addr = dma_buf_next;
> + soff = 0;
> + doff = fsl_chan->fsc.addr_width;
> + }
> +
> + fill_tcd_params(fsl_chan->edma, fsl_desc->tcd[i].vtcd, src_addr,
> + dst_addr, fsl_chan->fsc.attr, soff, nbytes, 0,
> + iter, iter, doff, last_sg, true, false, true);
> + dma_buf_next += period_len;
> + }
> +
> + return vchan_tx_prep(&fsl_chan->vchan, &fsl_desc->vdesc, flags);
> +}
--
~Vinod
--
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