linux-kernel - Re: [PATCH v3 06/12] dmaengine: stm32-dma3: add DMA

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Date: Mon, 20 May 2024 14:41:51 -0400
From: Frank Li <Frank.li@....com>
To: Amelie Delaunay <amelie.delaunay@...s.st.com>
Cc: Vinod Koul <vkoul@...nel.org>, Rob Herring <robh+dt@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	dmaengine@...r.kernel.org, devicetree@...r.kernel.org,
	linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: Re: [PATCH v3 06/12] dmaengine: stm32-dma3: add DMA_CYCLIC capability

On Mon, May 20, 2024 at 05:49:42PM +0200, Amelie Delaunay wrote:
> Add DMA_CYCLIC capability and relative device_prep_dma_cyclic ops with
> stm32_dma3_prep_dma_cyclic(). It reuses stm32_dma3_chan_prep_hw() and
> stm32_dma3_chan_prep_hwdesc() helpers.
> 
> Signed-off-by: Amelie Delaunay <amelie.delaunay@...s.st.com>
> ---
>  drivers/dma/stm32/stm32-dma3.c | 77 ++++++++++++++++++++++++++++++++++
>  1 file changed, 77 insertions(+)
> 
> diff --git a/drivers/dma/stm32/stm32-dma3.c b/drivers/dma/stm32/stm32-dma3.c
> index 134c08a7ee96..aae9fc018b1d 100644
> --- a/drivers/dma/stm32/stm32-dma3.c
> +++ b/drivers/dma/stm32/stm32-dma3.c
> @@ -1021,6 +1021,81 @@ static struct dma_async_tx_descriptor *stm32_dma3_prep_slave_sg(struct dma_chan
>  	return NULL;
>  }
>  
> +static struct dma_async_tx_descriptor *stm32_dma3_prep_dma_cyclic(struct dma_chan *c,
> +								  dma_addr_t buf_addr,
> +								  size_t buf_len, size_t period_len,
> +								  enum dma_transfer_direction dir,
> +								  unsigned long flags)
> +{
> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
> +	struct stm32_dma3_swdesc *swdesc;
> +	dma_addr_t src, dst;
> +	u32 count, i, ctr1, ctr2;
> +	int ret;
> +
> +	if (!buf_len || !period_len || period_len > STM32_DMA3_MAX_BLOCK_SIZE) {
> +		dev_err(chan2dev(chan), "Invalid buffer/period length\n");
> +		return NULL;
> +	}
> +
> +	if (buf_len % period_len) {
> +		dev_err(chan2dev(chan), "Buffer length not multiple of period length\n");
> +		return NULL;
> +	}
> +
> +	count = buf_len / period_len;
> +	swdesc = stm32_dma3_chan_desc_alloc(chan, count);
> +	if (!swdesc)
> +		return NULL;
> +
> +	if (dir == DMA_MEM_TO_DEV) {
> +		src = buf_addr;
> +		dst = chan->dma_config.dst_addr;
> +
> +		ret = stm32_dma3_chan_prep_hw(chan, DMA_MEM_TO_DEV, &swdesc->ccr, &ctr1, &ctr2,
> +					      src, dst, period_len);
> +	} else if (dir == DMA_DEV_TO_MEM) {
> +		src = chan->dma_config.src_addr;
> +		dst = buf_addr;
> +
> +		ret = stm32_dma3_chan_prep_hw(chan, DMA_DEV_TO_MEM, &swdesc->ccr, &ctr1, &ctr2,
> +					      src, dst, period_len);
> +	} else {
> +		dev_err(chan2dev(chan), "Invalid direction\n");
> +		ret = -EINVAL;
> +	}
> +
> +	if (ret)
> +		goto err_desc_free;
> +
> +	for (i = 0; i < count; i++) {
> +		if (dir == DMA_MEM_TO_DEV) {
> +			src = buf_addr + i * period_len;
> +			dst = chan->dma_config.dst_addr;
> +		} else { /* (dir == DMA_DEV_TO_MEM || dir == DMA_MEM_TO_MEM) */

look like comment is wrong.

DMA_MEM_TO_MEM will return -EINVAL at previous check. 

> +			src = chan->dma_config.src_addr;
> +			dst = buf_addr + i * period_len;
> +		}
> +
> +		stm32_dma3_chan_prep_hwdesc(chan, swdesc, i, src, dst, period_len,
> +					    ctr1, ctr2, i == (count - 1), true);
> +	}
> +
> +	/* Enable Error interrupts */
> +	swdesc->ccr |= CCR_USEIE | CCR_ULEIE | CCR_DTEIE;
> +	/* Enable Transfer state interrupts */
> +	swdesc->ccr |= CCR_TCIE;
> +
> +	swdesc->cyclic = true;
> +
> +	return vchan_tx_prep(&chan->vchan, &swdesc->vdesc, flags);
> +
> +err_desc_free:
> +	stm32_dma3_chan_desc_free(chan, swdesc);
> +
> +	return NULL;
> +}
> +
>  static void stm32_dma3_caps(struct dma_chan *c, struct dma_slave_caps *caps)
>  {
>  	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
> @@ -1255,6 +1330,7 @@ static int stm32_dma3_probe(struct platform_device *pdev)
>  
>  	dma_cap_set(DMA_SLAVE, dma_dev->cap_mask);
>  	dma_cap_set(DMA_PRIVATE, dma_dev->cap_mask);
> +	dma_cap_set(DMA_CYCLIC, dma_dev->cap_mask);
>  	dma_dev->dev = &pdev->dev;
>  	/*
>  	 * This controller supports up to 8-byte buswidth depending on the port used and the
> @@ -1277,6 +1353,7 @@ static int stm32_dma3_probe(struct platform_device *pdev)
>  	dma_dev->device_alloc_chan_resources = stm32_dma3_alloc_chan_resources;
>  	dma_dev->device_free_chan_resources = stm32_dma3_free_chan_resources;
>  	dma_dev->device_prep_slave_sg = stm32_dma3_prep_slave_sg;
> +	dma_dev->device_prep_dma_cyclic = stm32_dma3_prep_dma_cyclic;
>  	dma_dev->device_caps = stm32_dma3_caps;
>  	dma_dev->device_config = stm32_dma3_config;
>  	dma_dev->device_terminate_all = stm32_dma3_terminate_all;
> -- 
> 2.25.1
>