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

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Message-ID: <0b9a47c3-9064-4439-a0d8-08087b524534@foss.st.com>
Date: Mon, 27 May 2024 10:41:51 +0200
From: Amelie Delaunay <amelie.delaunay@...s.st.com>
To: Frank Li <Frank.li@....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 5/20/24 20:41, Frank Li wrote:
> 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.
> 

Indeed. I'll fix it in v4.

>> +			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
>>