linux-hardening - [PATCH v2 11/12] dmaengine: stm32-dma3: defer channel registration to specify channel name

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Date: Tue, 7 May 2024 14:54:41 +0200
From: Amelie Delaunay <amelie.delaunay@...s.st.com>
To: 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>
CC: <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>,
        Amelie Delaunay
	<amelie.delaunay@...s.st.com>
Subject: [PATCH v2 11/12] dmaengine: stm32-dma3: defer channel registration to specify channel name

On STM32 DMA3, channels can be reserved, so they are non available for
Linux. This non-availability creates a mismatch between dma_chan id and
DMA3 channel id.

Use dma_async_device_channel_register() to register the channels
after controller registration and change the default channel name, so that
it can match the name in the Reference Manual and ease requesting a channel
thanks to its name.

Signed-off-by: Amelie Delaunay <amelie.delaunay@...s.st.com>
---
 drivers/dma/stm32/stm32-dma3.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/dma/stm32/stm32-dma3.c b/drivers/dma/stm32/stm32-dma3.c
index c7df5d4d34d6..bc6fa7fdcb07 100644
--- a/drivers/dma/stm32/stm32-dma3.c
+++ b/drivers/dma/stm32/stm32-dma3.c
@@ -1723,9 +1723,6 @@ static int stm32_dma3_probe(struct platform_device *pdev)
 		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);
@@ -1733,14 +1730,26 @@ static int stm32_dma3_probe(struct platform_device *pdev)
 		goto err_clk_disable;
 
 	for (i = 0; i < ddata->dma_channels; i++) {
+		char name[12];
+
 		if (chan_reserved & BIT(i))
 			continue;
 
+		chan = &ddata->chans[i];
+		snprintf(name, sizeof(name), "dma%dchan%d", ddata->dma_dev.dev_id, chan->id);
+
+		chan->vchan.desc_free = stm32_dma3_chan_vdesc_free;
+		vchan_init(&chan->vchan, dma_dev);
+
+		ret = dma_async_device_channel_register(&ddata->dma_dev, &chan->vchan.chan, name);
+		if (ret) {
+			dev_err_probe(&pdev->dev, ret, "Failed to register channel %s\n", name);
+			goto err_clk_disable;
+		}
+
 		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,
-- 
2.25.1