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Message-ID: <2da93910-01dc-4cfe-994e-3a0d70d2bd19@foss.st.com>
Date: Fri, 17 May 2024 11:42:17 +0200
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Subject: Re: [PATCH 05/12] dmaengine: Add STM32 DMA3 support
To: Frank Li <Frank.li@nxp.com>
CC: Vinod Koul <vkoul@kernel.org>, Rob Herring <robh+dt@kernel.org>,
        Krzysztof
 Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley
	<conor+dt@kernel.org>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Alexandre
 Torgue <alexandre.torgue@foss.st.com>,
        <dmaengine@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        <linux-arm-kernel@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
        <linux-hardening@vger.kernel.org>
References: <20240423123302.1550592-1-amelie.delaunay@foss.st.com>
 <20240423123302.1550592-6-amelie.delaunay@foss.st.com>
 <ZkUFYoRCOOpAoIus@lizhi-Precision-Tower-5810>
 <408b4a20-680e-4bad-8971-ff98323ce04e@foss.st.com>
 <ZkY9zIfvaiA8h7Oq@lizhi-Precision-Tower-5810>
Content-Language: en-US
From: Amelie Delaunay <amelie.delaunay@foss.st.com>
In-Reply-To: <ZkY9zIfvaiA8h7Oq@lizhi-Precision-Tower-5810>
Content-Type: text/plain; charset="UTF-8"; format=flowed
Content-Transfer-Encoding: 7bit

On 5/16/24 19:09, Frank Li wrote:
> On Thu, May 16, 2024 at 05:25:58PM +0200, Amelie Delaunay wrote:
>> On 5/15/24 20:56, Frank Li wrote:
>>> On Tue, Apr 23, 2024 at 02:32:55PM +0200, Amelie Delaunay wrote:
>>>> STM32 DMA3 driver supports the 3 hardware configurations of the STM32 DMA3
>>>> controller:
> ...
>>>> +	writel_relaxed(hwdesc->cdar, ddata->base + STM32_DMA3_CDAR(id));
>>>> +	writel_relaxed(hwdesc->cllr, ddata->base + STM32_DMA3_CLLR(id));
>>>> +
>>>> +	/* Clear any pending interrupts */
>>>> +	csr = readl_relaxed(ddata->base + STM32_DMA3_CSR(id));
>>>> +	if (csr & CSR_ALL_F)
>>>> +		writel_relaxed(csr, ddata->base + STM32_DMA3_CFCR(id));
>>>> +
>>>> +	stm32_dma3_chan_dump_reg(chan);
>>>> +
>>>> +	ccr = readl_relaxed(ddata->base + STM32_DMA3_CCR(id));
>>>> +	writel_relaxed(ccr | CCR_EN, ddata->base + STM32_DMA3_CCR(id));
>>>
>>> This one should use writel instead of writel_relaxed because it need
>>> dma_wmb() as barrier for preious write complete.
>>>
>>> Frank
>>>
>>
>> ddata->base is Device memory type thanks to ioremap() use, so it is strongly
>> ordered and non-cacheable.
>> DMA3 is outside CPU cluster, its registers are accessible through AHB bus.
>> dma_wmb() (in case of writel instead of writel_relaxed) is useless in that
>> case: it won't ensure the propagation on the bus is complete, and it will
>> have impacts on the system.
>> That's why CCR register is written once,  then it is read before CCR_EN is
>> set and being written again, with _relaxed(), because registers are behind a
>> bus, and ioremapped with Device memory type which ensures it is strongly
>> ordered and non-cacheable.
> 
> regardless memory map, writel_relaxed() just make sure io write and read is
> orderred, not necessary order with other memory access. only readl and
> writel make sure order with other memory read/write.
> 
> 1. Write src_addr to descriptor
> 2. dma_wmb()
> 3. Write "ready" to descriptor
> 4. enable channel or doorbell by write a register.
> 
> if 4 use writel_relaxe(). because 3 write to DDR, which difference place of
> mmio, 4 may happen before 3.  Your can refer axi order model.
> 
> 4 have to use ONE writel(), to make sure 3 already write to DDR.
> 
> You need use at least one writel() to make sure all nornmal memory finish.
> 

+    writel_relaxed(chan->swdesc->ccr, ddata->base + STM32_DMA3_CCR(id));
+    writel_relaxed(hwdesc->ctr1, ddata->base + STM32_DMA3_CTR1(id));
+    writel_relaxed(hwdesc->ctr2, ddata->base + STM32_DMA3_CTR2(id));
+    writel_relaxed(hwdesc->cbr1, ddata->base + STM32_DMA3_CBR1(id));
+    writel_relaxed(hwdesc->csar, ddata->base + STM32_DMA3_CSAR(id));
+    writel_relaxed(hwdesc->cdar, ddata->base + STM32_DMA3_CDAR(id));
+    writel_relaxed(hwdesc->cllr, ddata->base + STM32_DMA3_CLLR(id));

These writel_relaxed() are from descriptors to DMA3 registers 
(descriptors being prepared "a long time ago" during _prep_).
As I said previously, DMA3 registers are outside CPU cluster, accessible 
through AHB bus, and ddata->base to address registers is ioremapped as 
Device memory type, non-cacheable and strongly ordered.

arch/arm/include/asm/io.h:
/*
* ioremap() and friends.
*
* ioremap() takes a resource address, and size.  Due to the ARM memory
* types, it is important to use the correct ioremap() function as each
* mapping has specific properties.
*
* Function		Memory type	Cacheability	Cache hint
* *ioremap()*		*Device*		*n/a*		*n/a*
* ioremap_cache()	Normal		Writeback	Read allocate
* ioremap_wc()		Normal		Non-cacheable	n/a
* ioremap_wt()		Normal		Non-cacheable	n/a
*
* All device mappings have the following properties:
* - no access speculation
* - no repetition (eg, on return from an exception)
* - number, order and size of accesses are maintained
* - unaligned accesses are "unpredictable"
* - writes may be delayed before they hit the endpoint device

On our platforms, we know that to ensure the writes have hit the 
endpoint device (aka DMA3 registers), a read have to be done before.
And that's what is done before enabling the channel:

+    ccr = readl_relaxed(ddata->base + STM32_DMA3_CCR(id));
+    writel_relaxed(ccr | CCR_EN, ddata->base + STM32_DMA3_CCR(id));

If there was an issue in this part of the code, it means channel would 
be started while it is wrongly programmed. In that case, DMA3 would 
raise a User Setting Error interrupt and disable the channel. User 
Setting Error is managed in this driver 
(USEF/stm32_dma3_check_user_setting()). And we never had reached a 
situation.

>>
>>>> +
>>>> +	chan->dma_status = DMA_IN_PROGRESS;
>>>> +
>>>> +	dev_dbg(chan2dev(chan), "vchan %pK: started\n", &chan->vchan);
>>>> +}
>>>> +
>>>> +static int stm32_dma3_chan_suspend(struct stm32_dma3_chan *chan, bool susp)
>>>> +{
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	u32 csr, ccr = readl_relaxed(ddata->base + STM32_DMA3_CCR(chan->id)) & ~CCR_EN;
>>>> +	int ret = 0;
>>>> +
>>>> +	if (susp)
>>>> +		ccr |= CCR_SUSP;
>>>> +	else
>>>> +		ccr &= ~CCR_SUSP;
>>>> +
>>>> +	writel_relaxed(ccr, ddata->base + STM32_DMA3_CCR(chan->id));
>>>> +
>>>> +	if (susp) {
>>>> +		ret = readl_relaxed_poll_timeout_atomic(ddata->base + STM32_DMA3_CSR(chan->id), csr,
>>>> +							csr & CSR_SUSPF, 1, 10);
>>>> +		if (!ret)
>>>> +			writel_relaxed(CFCR_SUSPF, ddata->base + STM32_DMA3_CFCR(chan->id));
>>>> +
>>>> +		stm32_dma3_chan_dump_reg(chan);
>>>> +	}
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static void stm32_dma3_chan_reset(struct stm32_dma3_chan *chan)
>>>> +{
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	u32 ccr = readl_relaxed(ddata->base + STM32_DMA3_CCR(chan->id)) & ~CCR_EN;
>>>> +
>>>> +	writel_relaxed(ccr |= CCR_RESET, ddata->base + STM32_DMA3_CCR(chan->id));
>>>> +}
>>>> +
>>>> +static int stm32_dma3_chan_stop(struct stm32_dma3_chan *chan)
>>>> +{
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	u32 ccr;
>>>> +	int ret = 0;
>>>> +
>>>> +	chan->dma_status = DMA_COMPLETE;
>>>> +
>>>> +	/* Disable interrupts */
>>>> +	ccr = readl_relaxed(ddata->base + STM32_DMA3_CCR(chan->id));
>>>> +	writel_relaxed(ccr & ~(CCR_ALLIE | CCR_EN), ddata->base + STM32_DMA3_CCR(chan->id));
>>>> +
>>>> +	if (!(ccr & CCR_SUSP) && (ccr & CCR_EN)) {
>>>> +		/* Suspend the channel */
>>>> +		ret = stm32_dma3_chan_suspend(chan, true);
>>>> +		if (ret)
>>>> +			dev_warn(chan2dev(chan), "%s: timeout, data might be lost\n", __func__);
>>>> +	}
>>>> +
>>>> +	/*
>>>> +	 * Reset the channel: this causes the reset of the FIFO and the reset of the channel
>>>> +	 * internal state, the reset of CCR_EN and CCR_SUSP bits.
>>>> +	 */
>>>> +	stm32_dma3_chan_reset(chan);
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static void stm32_dma3_chan_complete(struct stm32_dma3_chan *chan)
>>>> +{
>>>> +	if (!chan->swdesc)
>>>> +		return;
>>>> +
>>>> +	vchan_cookie_complete(&chan->swdesc->vdesc);
>>>> +	chan->swdesc = NULL;
>>>> +	stm32_dma3_chan_start(chan);
>>>> +}
>>>> +
>>>> +static irqreturn_t stm32_dma3_chan_irq(int irq, void *devid)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = devid;
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	u32 misr, csr, ccr;
>>>> +
>>>> +	spin_lock(&chan->vchan.lock);
>>>> +
>>>> +	misr = readl_relaxed(ddata->base + STM32_DMA3_MISR);
>>>> +	if (!(misr & MISR_MIS(chan->id))) {
>>>> +		spin_unlock(&chan->vchan.lock);
>>>> +		return IRQ_NONE;
>>>> +	}
>>>> +
>>>> +	csr = readl_relaxed(ddata->base + STM32_DMA3_CSR(chan->id));
>>>> +	ccr = readl_relaxed(ddata->base + STM32_DMA3_CCR(chan->id)) & CCR_ALLIE;
>>>> +
>>>> +	if (csr & CSR_TCF && ccr & CCR_TCIE) {
>>>> +		if (chan->swdesc->cyclic)
>>>> +			vchan_cyclic_callback(&chan->swdesc->vdesc);
>>>> +		else
>>>> +			stm32_dma3_chan_complete(chan);
>>>> +	}
>>>> +
>>>> +	if (csr & CSR_USEF && ccr & CCR_USEIE) {
>>>> +		dev_err(chan2dev(chan), "User setting error\n");
>>>> +		chan->dma_status = DMA_ERROR;
>>>> +		/* CCR.EN automatically cleared by HW */
>>>> +		stm32_dma3_check_user_setting(chan);
>>>> +		stm32_dma3_chan_reset(chan);
>>>> +	}
>>>> +
>>>> +	if (csr & CSR_ULEF && ccr & CCR_ULEIE) {
>>>> +		dev_err(chan2dev(chan), "Update link transfer error\n");
>>>> +		chan->dma_status = DMA_ERROR;
>>>> +		/* CCR.EN automatically cleared by HW */
>>>> +		stm32_dma3_chan_reset(chan);
>>>> +	}
>>>> +
>>>> +	if (csr & CSR_DTEF && ccr & CCR_DTEIE) {
>>>> +		dev_err(chan2dev(chan), "Data transfer error\n");
>>>> +		chan->dma_status = DMA_ERROR;
>>>> +		/* CCR.EN automatically cleared by HW */
>>>> +		stm32_dma3_chan_reset(chan);
>>>> +	}
>>>> +
>>>> +	/*
>>>> +	 * Half Transfer Interrupt may be disabled but Half Transfer Flag can be set,
>>>> +	 * ensure HTF flag to be cleared, with other flags.
>>>> +	 */
>>>> +	csr &= (ccr | CCR_HTIE);
>>>> +
>>>> +	if (csr)
>>>> +		writel_relaxed(csr, ddata->base + STM32_DMA3_CFCR(chan->id));
>>>> +
>>>> +	spin_unlock(&chan->vchan.lock);
>>>> +
>>>> +	return IRQ_HANDLED;
>>>> +}
>>>> +
>>>> +static int stm32_dma3_alloc_chan_resources(struct dma_chan *c)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	u32 id = chan->id, csemcr, ccid;
>>>> +	int ret;
>>>> +
>>>> +	ret = pm_runtime_resume_and_get(ddata->dma_dev.dev);
>>>> +	if (ret < 0)
>>>> +		return ret;
>>>
>>> It doesn't prefer runtime pm get at alloc dma chan, many client driver
>>> doesn't actual user dma when allocate dma chan.
>>>
>>> Ideally, resume get when issue_pending. Please refer pl330.c.
>>>
>>> You may add runtime pm later after enablement patch.
>>>
>>> Frank
>>>
>>
>> To well balance clock enable/disable, if pm_runtime_resume_and_get() (rather
>> than pm_runtime_get_sync() which doesn't decrement the counter in case of
>> error) is used when issue_pending, it means pm_runtime_put_sync() should be
>> done when transfer ends.
>>
>> terminate_all is not always called, so put_sync can't be used only there, it
>> should be conditionnally used in terminate_all, but also in interrupt
>> handler, on error events and on transfer completion event, provided that it
>> is the last transfer complete event (last item of the linked-list).
>>
>> For clients with high transfer rate, it means a lot of clock enable/disable.
>> Moreover, DMA3 clock is managed by Secure OS. So it means a lot of
>> non-secure/secure world transitions.
>>
>> I prefer to keep the implementation as it is for now, and possibly propose
>> runtime pm improvement later, with autosuspend.
> 
> 
> Autosuspend is perfered. we try to use pm_runtime_get/put at channel alloc
> /free before, but this solution are rejected by community.
> 
> you can leave clock on for this enablement patch and add runtime pm later
> time.
> 
> Frank
> 

Current implementation leaves the clock off if no channel is requested. 
It also disables the clock if platform is suspended.
I just took example from what is done in stm32 drivers.

I have further patches, not proposed in this series which adds a basic 
support of DMA3. There will be improvements, including runtime pm, in 
next series.

Amelie

>>
>> Amelie
>>
>>>> +
>>>> +	/* Ensure the channel is free */
>>>> +	if (chan->semaphore_mode &&
>>>> +	    readl_relaxed(ddata->base + STM32_DMA3_CSEMCR(chan->id)) & CSEMCR_SEM_MUTEX) {
>>>> +		ret = -EBUSY;
>>>> +		goto err_put_sync;
>>>> +	}
>>>> +
>>>> +	chan->lli_pool = dmam_pool_create(dev_name(&c->dev->device), c->device->dev,
>>>> +					  sizeof(struct stm32_dma3_hwdesc),
>>>> +					  __alignof__(struct stm32_dma3_hwdesc), 0);
>>>> +	if (!chan->lli_pool) {
>>>> +		dev_err(chan2dev(chan), "Failed to create LLI pool\n");
>>>> +		ret = -ENOMEM;
>>>> +		goto err_put_sync;
>>>> +	}
>>>> +
>>>> +	/* Take the channel semaphore */
>>>> +	if (chan->semaphore_mode) {
>>>> +		writel_relaxed(CSEMCR_SEM_MUTEX, ddata->base + STM32_DMA3_CSEMCR(id));
>>>> +		csemcr = readl_relaxed(ddata->base + STM32_DMA3_CSEMCR(id));
>>>> +		ccid = FIELD_GET(CSEMCR_SEM_CCID, csemcr);
>>>> +		/* Check that the channel is well taken */
>>>> +		if (ccid != CCIDCFGR_CID1) {
>>>> +			dev_err(chan2dev(chan), "Not under CID1 control (in-use by CID%d)\n", ccid);
>>>> +			ret = -EPERM;
>>>> +			goto err_pool_destroy;
>>>> +		}
>>>> +		dev_dbg(chan2dev(chan), "Under CID1 control (semcr=0x%08x)\n", csemcr);
>>>> +	}
>>>> +
>>>> +	return 0;
>>>> +
>>>> +err_pool_destroy:
>>>> +	dmam_pool_destroy(chan->lli_pool);
>>>> +	chan->lli_pool = NULL;
>>>> +
>>>> +err_put_sync:
>>>> +	pm_runtime_put_sync(ddata->dma_dev.dev);
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static void stm32_dma3_free_chan_resources(struct dma_chan *c)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	unsigned long flags;
>>>> +
>>>> +	/* Ensure channel is in idle state */
>>>> +	spin_lock_irqsave(&chan->vchan.lock, flags);
>>>> +	stm32_dma3_chan_stop(chan);
>>>> +	chan->swdesc = NULL;
>>>> +	spin_unlock_irqrestore(&chan->vchan.lock, flags);
>>>> +
>>>> +	vchan_free_chan_resources(to_virt_chan(c));
>>>> +
>>>> +	dmam_pool_destroy(chan->lli_pool);
>>>> +	chan->lli_pool = NULL;
>>>> +
>>>> +	/* Release the channel semaphore */
>>>> +	if (chan->semaphore_mode)
>>>> +		writel_relaxed(0, ddata->base + STM32_DMA3_CSEMCR(chan->id));
>>>> +
>>>> +	pm_runtime_put_sync(ddata->dma_dev.dev);
>>>> +
>>>> +	/* Reset configuration */
>>>> +	memset(&chan->dt_config, 0, sizeof(chan->dt_config));
>>>> +	memset(&chan->dma_config, 0, sizeof(chan->dma_config));
>>>> +}
>>>> +
>>>> +static struct dma_async_tx_descriptor *stm32_dma3_prep_slave_sg(struct dma_chan *c,
>>>> +								struct scatterlist *sgl,
>>>> +								unsigned int sg_len,
>>>> +								enum dma_transfer_direction dir,
>>>> +								unsigned long flags, void *context)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
>>>> +	struct stm32_dma3_swdesc *swdesc;
>>>> +	struct scatterlist *sg;
>>>> +	size_t len;
>>>> +	dma_addr_t sg_addr, dev_addr, src, dst;
>>>> +	u32 i, j, count, ctr1, ctr2;
>>>> +	int ret;
>>>> +
>>>> +	count = sg_len;
>>>> +	for_each_sg(sgl, sg, sg_len, i) {
>>>> +		len = sg_dma_len(sg);
>>>> +		if (len > STM32_DMA3_MAX_BLOCK_SIZE)
>>>> +			count += DIV_ROUND_UP(len, STM32_DMA3_MAX_BLOCK_SIZE) - 1;
>>>> +	}
>>>> +
>>>> +	swdesc = stm32_dma3_chan_desc_alloc(chan, count);
>>>> +	if (!swdesc)
>>>> +		return NULL;
>>>> +
>>>> +	/* sg_len and i correspond to the initial sgl; count and j correspond to the hwdesc LL */
>>>> +	j = 0;
>>>> +	for_each_sg(sgl, sg, sg_len, i) {
>>>> +		sg_addr = sg_dma_address(sg);
>>>> +		dev_addr = (dir == DMA_MEM_TO_DEV) ? chan->dma_config.dst_addr :
>>>> +						     chan->dma_config.src_addr;
>>>> +		len = sg_dma_len(sg);
>>>> +
>>>> +		do {
>>>> +			size_t chunk = min_t(size_t, len, STM32_DMA3_MAX_BLOCK_SIZE);
>>>> +
>>>> +			if (dir == DMA_MEM_TO_DEV) {
>>>> +				src = sg_addr;
>>>> +				dst = dev_addr;
>>>> +
>>>> +				ret = stm32_dma3_chan_prep_hw(chan, dir, &swdesc->ccr, &ctr1, &ctr2,
>>>> +							      src, dst, chunk);
>>>> +
>>>> +				if (FIELD_GET(CTR1_DINC, ctr1))
>>>> +					dev_addr += chunk;
>>>> +			} else { /* (dir == DMA_DEV_TO_MEM || dir == DMA_MEM_TO_MEM) */
>>>> +				src = dev_addr;
>>>> +				dst = sg_addr;
>>>> +
>>>> +				ret = stm32_dma3_chan_prep_hw(chan, dir, &swdesc->ccr, &ctr1, &ctr2,
>>>> +							      src, dst, chunk);
>>>> +
>>>> +				if (FIELD_GET(CTR1_SINC, ctr1))
>>>> +					dev_addr += chunk;
>>>> +			}
>>>> +
>>>> +			if (ret)
>>>> +				goto err_desc_free;
>>>> +
>>>> +			stm32_dma3_chan_prep_hwdesc(chan, swdesc, j, src, dst, chunk,
>>>> +						    ctr1, ctr2, j == (count - 1), false);
>>>> +
>>>> +			sg_addr += chunk;
>>>> +			len -= chunk;
>>>> +			j++;
>>>> +		} while (len);
>>>> +	}
>>>> +
>>>> +	/* Enable Error interrupts */
>>>> +	swdesc->ccr |= CCR_USEIE | CCR_ULEIE | CCR_DTEIE;
>>>> +	/* Enable Transfer state interrupts */
>>>> +	swdesc->ccr |= CCR_TCIE;
>>>> +
>>>> +	swdesc->cyclic = false;
>>>> +
>>>> +	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);
>>>> +
>>>> +	if (!chan->fifo_size) {
>>>> +		caps->max_burst = 0;
>>>> +		caps->src_addr_widths &= ~BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
>>>> +		caps->dst_addr_widths &= ~BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
>>>> +	} else {
>>>> +		/* Burst transfer should not exceed half of the fifo size */
>>>> +		caps->max_burst = chan->max_burst;
>>>> +		if (caps->max_burst < DMA_SLAVE_BUSWIDTH_8_BYTES) {
>>>> +			caps->src_addr_widths &= ~BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
>>>> +			caps->dst_addr_widths &= ~BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
>>>> +		}
>>>> +	}
>>>> +}
>>>> +
>>>> +static int stm32_dma3_config(struct dma_chan *c, struct dma_slave_config *config)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
>>>> +
>>>> +	memcpy(&chan->dma_config, config, sizeof(*config));
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static int stm32_dma3_terminate_all(struct dma_chan *c)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
>>>> +	unsigned long flags;
>>>> +	LIST_HEAD(head);
>>>> +
>>>> +	spin_lock_irqsave(&chan->vchan.lock, flags);
>>>> +
>>>> +	if (chan->swdesc) {
>>>> +		vchan_terminate_vdesc(&chan->swdesc->vdesc);
>>>> +		chan->swdesc = NULL;
>>>> +	}
>>>> +
>>>> +	stm32_dma3_chan_stop(chan);
>>>> +
>>>> +	vchan_get_all_descriptors(&chan->vchan, &head);
>>>> +
>>>> +	spin_unlock_irqrestore(&chan->vchan.lock, flags);
>>>> +	vchan_dma_desc_free_list(&chan->vchan, &head);
>>>> +
>>>> +	dev_dbg(chan2dev(chan), "vchan %pK: terminated\n", &chan->vchan);
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static void stm32_dma3_synchronize(struct dma_chan *c)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
>>>> +
>>>> +	vchan_synchronize(&chan->vchan);
>>>> +}
>>>> +
>>>> +static void stm32_dma3_issue_pending(struct dma_chan *c)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
>>>> +	unsigned long flags;
>>>> +
>>>> +	spin_lock_irqsave(&chan->vchan.lock, flags);
>>>> +
>>>> +	if (vchan_issue_pending(&chan->vchan) && !chan->swdesc) {
>>>> +		dev_dbg(chan2dev(chan), "vchan %pK: issued\n", &chan->vchan);
>>>> +		stm32_dma3_chan_start(chan);
>>>> +	}
>>>> +
>>>> +	spin_unlock_irqrestore(&chan->vchan.lock, flags);
>>>> +}
>>>> +
>>>> +static bool stm32_dma3_filter_fn(struct dma_chan *c, void *fn_param)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	struct stm32_dma3_dt_conf *conf = fn_param;
>>>> +	u32 mask, semcr;
>>>> +	int ret;
>>>> +
>>>> +	dev_dbg(c->device->dev, "%s(%s): req_line=%d ch_conf=%08x tr_conf=%08x\n",
>>>> +		__func__, dma_chan_name(c), conf->req_line, conf->ch_conf, conf->tr_conf);
>>>> +
>>>> +	if (!of_property_read_u32(c->device->dev->of_node, "dma-channel-mask", &mask))
>>>> +		if (!(mask & BIT(chan->id)))
>>>> +			return false;
>>>> +
>>>> +	ret = pm_runtime_resume_and_get(ddata->dma_dev.dev);
>>>> +	if (ret < 0)
>>>> +		return false;
>>>> +	semcr = readl_relaxed(ddata->base + STM32_DMA3_CSEMCR(chan->id));
>>>> +	pm_runtime_put_sync(ddata->dma_dev.dev);
>>>> +
>>>> +	/* Check if chan is free */
>>>> +	if (semcr & CSEMCR_SEM_MUTEX)
>>>> +		return false;
>>>> +
>>>> +	/* Check if chan fifo fits well */
>>>> +	if (FIELD_GET(STM32_DMA3_DT_FIFO, conf->ch_conf) != chan->fifo_size)
>>>> +		return false;
>>>> +
>>>> +	return true;
>>>> +}
>>>> +
>>>> +static struct dma_chan *stm32_dma3_of_xlate(struct of_phandle_args *dma_spec, struct of_dma *ofdma)
>>>> +{
>>>> +	struct stm32_dma3_ddata *ddata = ofdma->of_dma_data;
>>>> +	dma_cap_mask_t mask = ddata->dma_dev.cap_mask;
>>>> +	struct stm32_dma3_dt_conf conf;
>>>> +	struct stm32_dma3_chan *chan;
>>>> +	struct dma_chan *c;
>>>> +
>>>> +	if (dma_spec->args_count < 3) {
>>>> +		dev_err(ddata->dma_dev.dev, "Invalid args count\n");
>>>> +		return NULL;
>>>> +	}
>>>> +
>>>> +	conf.req_line = dma_spec->args[0];
>>>> +	conf.ch_conf = dma_spec->args[1];
>>>> +	conf.tr_conf = dma_spec->args[2];
>>>> +
>>>> +	if (conf.req_line >= ddata->dma_requests) {
>>>> +		dev_err(ddata->dma_dev.dev, "Invalid request line\n");
>>>> +		return NULL;
>>>> +	}
>>>> +
>>>> +	/* Request dma channel among the generic dma controller list */
>>>> +	c = dma_request_channel(mask, stm32_dma3_filter_fn, &conf);
>>>> +	if (!c) {
>>>> +		dev_err(ddata->dma_dev.dev, "No suitable channel found\n");
>>>> +		return NULL;
>>>> +	}
>>>> +
>>>> +	chan = to_stm32_dma3_chan(c);
>>>> +	chan->dt_config = conf;
>>>> +
>>>> +	return c;
>>>> +}
>>>> +
>>>> +static u32 stm32_dma3_check_rif(struct stm32_dma3_ddata *ddata)
>>>> +{
>>>> +	u32 chan_reserved, mask = 0, i, ccidcfgr, invalid_cid = 0;
>>>> +
>>>> +	/* Reserve Secure channels */
>>>> +	chan_reserved = readl_relaxed(ddata->base + STM32_DMA3_SECCFGR);
>>>> +
>>>> +	/*
>>>> +	 * CID filtering must be configured to ensure that the DMA3 channel will inherit the CID of
>>>> +	 * the processor which is configuring and using the given channel.
>>>> +	 * In case CID filtering is not configured, dma-channel-mask property can be used to
>>>> +	 * specify available DMA channels to the kernel.
>>>> +	 */
>>>> +	of_property_read_u32(ddata->dma_dev.dev->of_node, "dma-channel-mask", &mask);
>>>> +
>>>> +	/* Reserve !CID-filtered not in dma-channel-mask, static CID != CID1, CID1 not allowed */
>>>> +	for (i = 0; i < ddata->dma_channels; i++) {
>>>> +		ccidcfgr = readl_relaxed(ddata->base + STM32_DMA3_CCIDCFGR(i));
>>>> +
>>>> +		if (!(ccidcfgr & CCIDCFGR_CFEN)) { /* !CID-filtered */
>>>> +			invalid_cid |= BIT(i);
>>>> +			if (!(mask & BIT(i))) /* Not in dma-channel-mask */
>>>> +				chan_reserved |= BIT(i);
>>>> +		} else { /* CID-filtered */
>>>> +			if (!(ccidcfgr & CCIDCFGR_SEM_EN)) { /* Static CID mode */
>>>> +				if (FIELD_GET(CCIDCFGR_SCID, ccidcfgr) != CCIDCFGR_CID1)
>>>> +					chan_reserved |= BIT(i);
>>>> +			} else { /* Semaphore mode */
>>>> +				if (!FIELD_GET(CCIDCFGR_SEM_WLIST_CID1, ccidcfgr))
>>>> +					chan_reserved |= BIT(i);
>>>> +				ddata->chans[i].semaphore_mode = true;
>>>> +			}
>>>> +		}
>>>> +		dev_dbg(ddata->dma_dev.dev, "chan%d: %s mode, %s\n", i,
>>>> +			!(ccidcfgr & CCIDCFGR_CFEN) ? "!CID-filtered" :
>>>> +			ddata->chans[i].semaphore_mode ? "Semaphore" : "Static CID",
>>>> +			(chan_reserved & BIT(i)) ? "denied" :
>>>> +			mask & BIT(i) ? "force allowed" : "allowed");
>>>> +	}
>>>> +
>>>> +	if (invalid_cid)
>>>> +		dev_warn(ddata->dma_dev.dev, "chan%*pbl have invalid CID configuration\n",
>>>> +			 ddata->dma_channels, &invalid_cid);
>>>> +
>>>> +	return chan_reserved;
>>>> +}
>>>> +
>>>> +static const struct of_device_id stm32_dma3_of_match[] = {
>>>> +	{ .compatible = "st,stm32-dma3", },
>>>> +	{ /* sentinel */},
>>>> +};
>>>> +MODULE_DEVICE_TABLE(of, stm32_dma3_of_match);
>>>> +
>>>> +static int stm32_dma3_probe(struct platform_device *pdev)
>>>> +{
>>>> +	struct device_node *np = pdev->dev.of_node;
>>>> +	struct stm32_dma3_ddata *ddata;
>>>> +	struct reset_control *reset;
>>>> +	struct stm32_dma3_chan *chan;
>>>> +	struct dma_device *dma_dev;
>>>> +	u32 master_ports, chan_reserved, i, verr;
>>>> +	u64 hwcfgr;
>>>> +	int ret;
>>>> +
>>>> +	ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
>>>> +	if (!ddata)
>>>> +		return -ENOMEM;
>>>> +	platform_set_drvdata(pdev, ddata);
>>>> +
>>>> +	dma_dev = &ddata->dma_dev;
>>>> +
>>>> +	ddata->base = devm_platform_ioremap_resource(pdev, 0);
>>>> +	if (IS_ERR(ddata->base))
>>>> +		return PTR_ERR(ddata->base);
>>>> +
>>>> +	ddata->clk = devm_clk_get(&pdev->dev, NULL);
>>>> +	if (IS_ERR(ddata->clk))
>>>> +		return dev_err_probe(&pdev->dev, PTR_ERR(ddata->clk), "Failed to get clk\n");
>>>> +
>>>> +	reset = devm_reset_control_get_optional(&pdev->dev, NULL);
>>>> +	if (IS_ERR(reset))
>>>> +		return dev_err_probe(&pdev->dev, PTR_ERR(reset), "Failed to get reset\n");
>>>> +
>>>> +	ret = clk_prepare_enable(ddata->clk);
>>>> +	if (ret)
>>>> +		return dev_err_probe(&pdev->dev, ret, "Failed to enable clk\n");
>>>> +
>>>> +	reset_control_reset(reset);
>>>> +
>>>> +	INIT_LIST_HEAD(&dma_dev->channels);
>>>> +
>>>> +	dma_cap_set(DMA_SLAVE, dma_dev->cap_mask);
>>>> +	dma_cap_set(DMA_PRIVATE, dma_dev->cap_mask);
>>>> +	dma_dev->dev = &pdev->dev;
>>>> +	/*
>>>> +	 * This controller supports up to 8-byte buswidth depending on the port used and the
>>>> +	 * channel, and can only access address at even boundaries, multiple of the buswidth.
>>>> +	 */
>>>> +	dma_dev->copy_align = DMAENGINE_ALIGN_8_BYTES;
>>>> +	dma_dev->src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
>>>> +				   BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
>>>> +				   BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) |
>>>> +				   BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
>>>> +	dma_dev->dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
>>>> +				   BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
>>>> +				   BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) |
>>>> +				   BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
>>>> +	dma_dev->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV) | BIT(DMA_MEM_TO_MEM);
>>>> +
>>>> +	dma_dev->descriptor_reuse = true;
>>>> +	dma_dev->max_sg_burst = STM32_DMA3_MAX_SEG_SIZE;
>>>> +	dma_dev->residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
>>>> +	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_caps = stm32_dma3_caps;
>>>> +	dma_dev->device_config = stm32_dma3_config;
>>>> +	dma_dev->device_terminate_all = stm32_dma3_terminate_all;
>>>> +	dma_dev->device_synchronize = stm32_dma3_synchronize;
>>>> +	dma_dev->device_tx_status = dma_cookie_status;
>>>> +	dma_dev->device_issue_pending = stm32_dma3_issue_pending;
>>>> +
>>>> +	/* if dma_channels is not modified, get it from hwcfgr1 */
>>>> +	if (of_property_read_u32(np, "dma-channels", &ddata->dma_channels)) {
>>>> +		hwcfgr = readl_relaxed(ddata->base + STM32_DMA3_HWCFGR1);
>>>> +		ddata->dma_channels = FIELD_GET(G_NUM_CHANNELS, hwcfgr);
>>>> +	}
>>>> +
>>>> +	/* if dma_requests is not modified, get it from hwcfgr2 */
>>>> +	if (of_property_read_u32(np, "dma-requests", &ddata->dma_requests)) {
>>>> +		hwcfgr = readl_relaxed(ddata->base + STM32_DMA3_HWCFGR2);
>>>> +		ddata->dma_requests = FIELD_GET(G_MAX_REQ_ID, hwcfgr) + 1;
>>>> +	}
>>>> +
>>>> +	/* G_MASTER_PORTS, G_M0_DATA_WIDTH_ENC, G_M1_DATA_WIDTH_ENC in HWCFGR1 */
>>>> +	hwcfgr = readl_relaxed(ddata->base + STM32_DMA3_HWCFGR1);
>>>> +	master_ports = FIELD_GET(G_MASTER_PORTS, hwcfgr);
>>>> +
>>>> +	ddata->ports_max_dw[0] = FIELD_GET(G_M0_DATA_WIDTH_ENC, hwcfgr);
>>>> +	if (master_ports == AXI64 || master_ports == AHB32) /* Single master port */
>>>> +		ddata->ports_max_dw[1] = DW_INVALID;
>>>> +	else /* Dual master ports */
>>>> +		ddata->ports_max_dw[1] = FIELD_GET(G_M1_DATA_WIDTH_ENC, hwcfgr);
>>>> +
>>>> +	ddata->chans = devm_kcalloc(&pdev->dev, ddata->dma_channels, sizeof(*ddata->chans),
>>>> +				    GFP_KERNEL);
>>>> +	if (!ddata->chans) {
>>>> +		ret = -ENOMEM;
>>>> +		goto err_clk_disable;
>>>> +	}
>>>> +
>>>> +	chan_reserved = stm32_dma3_check_rif(ddata);
>>>> +
>>>> +	if (chan_reserved == GENMASK(ddata->dma_channels - 1, 0)) {
>>>> +		ret = -ENODEV;
>>>> +		dev_err_probe(&pdev->dev, ret, "No channel available, abort registration\n");
>>>> +		goto err_clk_disable;
>>>> +	}
>>>> +
>>>> +	/* G_FIFO_SIZE x=0..7 in HWCFGR3 and G_FIFO_SIZE x=8..15 in HWCFGR4 */
>>>> +	hwcfgr = readl_relaxed(ddata->base + STM32_DMA3_HWCFGR3);
>>>> +	hwcfgr |= ((u64)readl_relaxed(ddata->base + STM32_DMA3_HWCFGR4)) << 32;
>>>> +
>>>> +	for (i = 0; i < ddata->dma_channels; i++) {
>>>> +		if (chan_reserved & BIT(i))
>>>> +			continue;
>>>> +
>>>> +		chan = &ddata->chans[i];
>>>> +		chan->id = i;
>>>> +		chan->fifo_size = get_chan_hwcfg(i, G_FIFO_SIZE(i), hwcfgr);
>>>> +		/* If chan->fifo_size > 0 then half of the fifo size, else no burst when no FIFO */
>>>> +		chan->max_burst = (chan->fifo_size) ? (1 << (chan->fifo_size + 1)) / 2 : 0;
>>>> +		chan->vchan.desc_free = stm32_dma3_chan_vdesc_free;
>>>> +
>>>> +		vchan_init(&chan->vchan, dma_dev);
>>>> +	}
>>>> +
>>>> +	ret = dmaenginem_async_device_register(dma_dev);
>>>> +	if (ret)
>>>> +		goto err_clk_disable;
>>>> +
>>>> +	for (i = 0; i < ddata->dma_channels; i++) {
>>>> +		if (chan_reserved & BIT(i))
>>>> +			continue;
>>>> +
>>>> +		ret = platform_get_irq(pdev, i);
>>>> +		if (ret < 0)
>>>> +			goto err_clk_disable;
>>>> +
>>>> +		chan = &ddata->chans[i];
>>>> +		chan->irq = ret;
>>>> +
>>>> +		ret = devm_request_irq(&pdev->dev, chan->irq, stm32_dma3_chan_irq, 0,
>>>> +				       dev_name(chan2dev(chan)), chan);
>>>> +		if (ret) {
>>>> +			dev_err_probe(&pdev->dev, ret, "Failed to request channel %s IRQ\n",
>>>> +				      dev_name(chan2dev(chan)));
>>>> +			goto err_clk_disable;
>>>> +		}
>>>> +	}
>>>> +
>>>> +	ret = of_dma_controller_register(np, stm32_dma3_of_xlate, ddata);
>>>> +	if (ret) {
>>>> +		dev_err_probe(&pdev->dev, ret, "Failed to register controller\n");
>>>> +		goto err_clk_disable;
>>>> +	}
>>>> +
>>>> +	verr = readl_relaxed(ddata->base + STM32_DMA3_VERR);
>>>> +
>>>> +	pm_runtime_set_active(&pdev->dev);
>>>> +	pm_runtime_enable(&pdev->dev);
>>>> +	pm_runtime_get_noresume(&pdev->dev);
>>>> +	pm_runtime_put(&pdev->dev);
>>>> +
>>>> +	dev_info(&pdev->dev, "STM32 DMA3 registered rev:%lu.%lu\n",
>>>> +		 FIELD_GET(VERR_MAJREV, verr), FIELD_GET(VERR_MINREV, verr));
>>>> +
>>>> +	return 0;
>>>> +
>>>> +err_clk_disable:
>>>> +	clk_disable_unprepare(ddata->clk);
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static void stm32_dma3_remove(struct platform_device *pdev)
>>>> +{
>>>> +	pm_runtime_disable(&pdev->dev);
>>>> +}
>>>> +
>>>> +static int stm32_dma3_runtime_suspend(struct device *dev)
>>>> +{
>>>> +	struct stm32_dma3_ddata *ddata = dev_get_drvdata(dev);
>>>> +
>>>> +	clk_disable_unprepare(ddata->clk);
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static int stm32_dma3_runtime_resume(struct device *dev)
>>>> +{
>>>> +	struct stm32_dma3_ddata *ddata = dev_get_drvdata(dev);
>>>> +	int ret;
>>>> +
>>>> +	ret = clk_prepare_enable(ddata->clk);
>>>> +	if (ret)
>>>> +		dev_err(dev, "Failed to enable clk: %d\n", ret);
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static const struct dev_pm_ops stm32_dma3_pm_ops = {
>>>> +	SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, pm_runtime_force_resume)
>>>> +	RUNTIME_PM_OPS(stm32_dma3_runtime_suspend, stm32_dma3_runtime_resume, NULL)
>>>> +};
>>>> +
>>>> +static struct platform_driver stm32_dma3_driver = {
>>>> +	.probe = stm32_dma3_probe,
>>>> +	.remove_new = stm32_dma3_remove,
>>>> +	.driver = {
>>>> +		.name = "stm32-dma3",
>>>> +		.of_match_table = stm32_dma3_of_match,
>>>> +		.pm = pm_ptr(&stm32_dma3_pm_ops),
>>>> +	},
>>>> +};
>>>> +
>>>> +static int __init stm32_dma3_init(void)
>>>> +{
>>>> +	return platform_driver_register(&stm32_dma3_driver);
>>>> +}
>>>> +
>>>> +subsys_initcall(stm32_dma3_init);
>>>> +
>>>> +MODULE_DESCRIPTION("STM32 DMA3 controller driver");
>>>> +MODULE_AUTHOR("Amelie Delaunay <amelie.delaunay@foss.st.com>");
>>>> +MODULE_LICENSE("GPL");
>>>> -- 
>>>> 2.25.1
>>>>