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Mon, 02 Nov 2026 01:07:25 -0800 (PST) Received: from cypher.home.roving-it.com ([2001:8b0:fb11:0:3889:86e0:d449:e2e1]) by smtp.googlemail.com with ESMTPSA id 5b1f17b1804b1-4abf5b27e46sm417879945e9.3.2026.11.02.01.07.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Nov 2026 01:07:24 -0800 (PST) From: Peter Robinson To: Florian Fainelli , Dave Stevenson , Ray Jui , Scott Branden , Vinod Koul , Frank Li , dmaengine@vger.kernel.org, devicetree@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, bcm-kernel-feedback-list@broadcom.com Cc: Peter Robinson Subject: [PATCH 3/9] dmaengine: bcm2835: Support controllers split across several nodes Date: Mon, 2 Nov 2026 09:06:53 +0000 Message-ID: <20261102090713.896324-4-pbrobinson@gmail.com> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261102090713.896324-1-pbrobinson@gmail.com> References: <20261102090713.896324-1-pbrobinson@gmail.com> X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Derive the index of the first channel from the register resource and only probe the channels it covers, so a controller can be described by several nodes. Initialise all IRQ slots, as the shared IRQ check scans the whole array. Existing device trees start at channel 0 and are unaffected. Signed-off-by: Peter Robinson --- drivers/dma/bcm2835-dma.c | 34 +++++++++++++++++++++++----------- 1 file changed, 23 insertions(+), 11 deletions(-) diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c index 96a39eb24559f..83ad8815759e8 100644 --- a/drivers/dma/bcm2835-dma.c +++ b/drivers/dma/bcm2835-dma.c @@ -52,12 +52,14 @@ struct bcm2835_dma_cfg { * @zero_page: bus address of zero page (to detect transactions copying from * zero page and avoid accessing memory if so) * @cfg: SoC specific controller properties + * @first_chan: hardware index of the first channel covered by @base */ struct bcm2835_dmadev { struct dma_device ddev; void __iomem *base; dma_addr_t zero_page; const struct bcm2835_dma_cfg *cfg; + unsigned int first_chan; }; struct bcm2835_dma_cb { @@ -175,8 +177,8 @@ struct bcm2835_desc { #define BCM2835_DMA_DATA_TYPE_S128 16 /* Valid only for channels 0 - 14, 15 has its own base address */ -#define BCM2835_DMA_CHAN(n) ((n) << 8) /* Base address */ -#define BCM2835_DMA_CHANIO(base, n) ((base) + BCM2835_DMA_CHAN(n)) +#define BCM2835_DMA_CHAN_SIZE 0x100 +#define BCM2835_DMA_CHAN(n) ((n) * BCM2835_DMA_CHAN_SIZE) /* Base address */ /* the max dma length for different channels */ #define MAX_DMA_LEN SZ_1G @@ -886,7 +888,7 @@ static int bcm2835_dma_chan_init(struct bcm2835_dmadev *d, int chan_id, c->vc.desc_free = bcm2835_dma_desc_free; vchan_init(&c->vc, &d->ddev); - c->chan_base = BCM2835_DMA_CHANIO(d->base, chan_id); + c->chan_base = d->base + BCM2835_DMA_CHAN(chan_id - d->first_chan); c->ch = chan_id; c->irq_number = irq; c->irq_flags = irq_flags; @@ -960,6 +962,7 @@ static int bcm2835_dma_probe(struct platform_device *pdev) { const struct bcm2835_dma_cfg *cfg; struct bcm2835_dmadev *od; + struct resource *res; void __iomem *base; int rc; int i, j; @@ -967,6 +970,7 @@ static int bcm2835_dma_probe(struct platform_device *pdev) int irq_flags; uint32_t chans_available; char chan_name[BCM2835_DMA_CHAN_NAME_SIZE]; + unsigned int chan_start, chan_end; cfg = of_device_get_match_data(&pdev->dev); if (!cfg) @@ -987,12 +991,18 @@ static int bcm2835_dma_probe(struct platform_device *pdev) dma_set_max_seg_size(&pdev->dev, 0x3FFFFFFF); - base = devm_platform_ioremap_resource(pdev, 0); + base = devm_platform_get_and_ioremap_resource(pdev, 0, &res); if (IS_ERR(base)) return PTR_ERR(base); + chan_start = (res->start / BCM2835_DMA_CHAN_SIZE) & 0xf; + chan_end = min_t(unsigned int, + chan_start + resource_size(res) / BCM2835_DMA_CHAN_SIZE, + BCM2835_DMA_MAX_DMA_CHAN_SUPPORTED + 1); + od->base = base; od->cfg = cfg; + od->first_chan = chan_start; dma_cap_set(DMA_SLAVE, od->ddev.cap_mask); dma_cap_set(DMA_PRIVATE, od->ddev.cap_mask); @@ -1037,12 +1047,13 @@ static int bcm2835_dma_probe(struct platform_device *pdev) } /* get irqs for each channel that we support */ - for (i = 0; i <= BCM2835_DMA_MAX_DMA_CHAN_SUPPORTED; i++) { + for (i = 0; i <= BCM2835_DMA_MAX_DMA_CHAN_SUPPORTED; i++) + irq[i] = -1; + + for (i = chan_start; i < chan_end; i++) { /* skip masked out channels */ - if (!(chans_available & (1 << i))) { - irq[i] = -1; + if (!(chans_available & (1 << i))) continue; - } /* get the named irq */ snprintf(chan_name, sizeof(chan_name), "dma%i", i); @@ -1057,11 +1068,11 @@ static int bcm2835_dma_probe(struct platform_device *pdev) * in case of channel >= 11 * use the 11th interrupt and that is shared */ - irq[i] = platform_get_irq(pdev, i < 11 ? i : 11); + irq[i] = platform_get_irq(pdev, min(i - chan_start, 11U)); } /* get irqs for each channel */ - for (i = 0; i <= BCM2835_DMA_MAX_DMA_CHAN_SUPPORTED; i++) { + for (i = chan_start; i < chan_end; i++) { /* skip channels without irq */ if (irq[i] < 0) continue; @@ -1080,7 +1091,8 @@ static int bcm2835_dma_probe(struct platform_device *pdev) goto err_no_dma; } - dev_dbg(&pdev->dev, "Initialized %i DMA channels\n", i); + dev_dbg(&pdev->dev, "Initialized DMA channels %u-%u\n", chan_start, + chan_end - 1); /* Device-tree DMA controller registration */ rc = of_dma_controller_register(pdev->dev.of_node, -- 2.56.0