From: Martin Sperl <kernel@xxxxxxxxxxxxxxxx>
The bcm2835 dma channel 11 to 14 only have a single shared irq line,
so this patch implements shared interrupts for these channels.
This patch also introduces 2 new device-tree properties
(optional for compatibility with older device-trees):
* brcm,dma-channel-shared-mask - default: 0x0780
* brcm,dma-shared-irq-index - default: 11
With this patch applied we now have 11 dma channels available to
the ARM side of the SOC.
Signed-off-by: Martin Sperl <kernel@xxxxxxxxxxxxxxxx>
Reviewed-by: Eric Anholt <eric@xxxxxxxxxx>
---
drivers/dma/bcm2835-dma.c | 64 ++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 58 insertions(+), 6 deletions(-)
diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
index e4ca980..fe7d5a6 100644
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -81,7 +81,9 @@ struct bcm2835_chan {
struct dma_pool *cb_pool;
void __iomem *chan_base;
+
int irq_number;
+ unsigned long irq_flags;
};
struct bcm2835_desc {
@@ -127,6 +129,20 @@ struct bcm2835_desc {
#define BCM2835_DMA_CHAN(n) ((n) << 8) /* Base address */
#define BCM2835_DMA_CHANIO(base, n) ((base) + BCM2835_DMA_CHAN(n))
+/*
+ * number of dma channels we support
+ * we do not support DMA channel 15, as it is in a separate IO range,
+ * does not have a separate IRQ line except for the "catch all IRQ line"
+ * finally this channel is used by the firmware so is not available
+ */
+#define BCM2835_DMA_MAX_CHANNEL_NUMBER 14
+
+/* the DMA channels 11 to 14 share a common interrupt */
+#define BCM2835_DMA_IRQ_SHARED_MASK_DEFAULT \
+ (BIT(11) | BIT(12) | BIT(13) | BIT(14))
+#define BCM2835_DMA_IRQ_SHARED_DEFAULT 11
+#define BCM2835_DMA_IRQ_ALL_DEFAULT 12
+
static inline struct bcm2835_dmadev *to_bcm2835_dma_dev(struct dma_device *d)
{
return container_of(d, struct bcm2835_dmadev, ddev);
@@ -215,6 +231,15 @@ static irqreturn_t bcm2835_dma_callback(int irq, void *data)
struct bcm2835_desc *d;
unsigned long flags;
+ /* check the shared interrupt */
+ if (c->irq_flags & IRQF_SHARED) {
+ /* check if the interrupt is enabled */
+ flags = readl(c->chan_base + BCM2835_DMA_CS);
+ /* if not set then we are not the reason for the irq */
+ if (!(flags & BCM2835_DMA_INT))
+ return IRQ_NONE;
+ }
+
spin_lock_irqsave(&c->vc.lock, flags);
/* Acknowledge interrupt */
@@ -250,7 +275,8 @@ static int bcm2835_dma_alloc_chan_resources(struct dma_chan *chan)
}
return request_irq(c->irq_number,
- bcm2835_dma_callback, 0, "DMA IRQ", c);
+ bcm2835_dma_callback,
+ c->irq_flags, "DMA IRQ", c);
}
static void bcm2835_dma_free_chan_resources(struct dma_chan *chan)
@@ -526,7 +552,8 @@ static int bcm2835_dma_terminate_all(struct dma_chan *chan)
return 0;
}
-static int bcm2835_dma_chan_init(struct bcm2835_dmadev *d, int chan_id, int irq)
+static int bcm2835_dma_chan_init(struct bcm2835_dmadev *d, int chan_id,
+ int irq, unsigned long irq_flags)
{
struct bcm2835_chan *c;
@@ -541,6 +568,7 @@ static int bcm2835_dma_chan_init(struct bcm2835_dmadev *d, int chan_id, int irq)
c->chan_base = BCM2835_DMA_CHANIO(d->base, chan_id);
c->ch = chan_id;
c->irq_number = irq;
+ c->irq_flags = irq_flags;
return 0;
}
@@ -586,7 +614,8 @@ static int bcm2835_dma_probe(struct platform_device *pdev)
int rc;
int i;
int irq;
- uint32_t chans_available;
+ unsigned long irq_flags;
+ u32 chans_available, chans_shared_irq_mask, shared_irq_index;
if (!pdev->dev.dma_mask)
pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
@@ -637,14 +666,37 @@ static int bcm2835_dma_probe(struct platform_device *pdev)
rc = -EINVAL;
goto err_no_dma;
}
+ /* we do not support more channels */
+ chans_available &= BIT(BCM2835_DMA_MAX_CHANNEL_NUMBER + 1) - 1;
+
+ /* get shared irq mask falling back to defaults */
+ chans_shared_irq_mask = BCM2835_DMA_IRQ_SHARED_MASK_DEFAULT;
+ of_property_read_u32(pdev->dev.of_node,
+ "brcm,dma-channel-shared-mask",
+ &chans_shared_irq_mask);
+
+ /* get shared irq index falling back to default */
+ shared_irq_index = BCM2835_DMA_IRQ_SHARED_DEFAULT;
+ of_property_read_u32(pdev->dev.of_node,
+ "brcm,dma-shared-irq-index",
+ &shared_irq_index);
+
+ /* loop over all channels */
+ for (i = 0; i <= fls(chans_available); i++) {
+ if (chans_shared_irq_mask & BIT(i)) {
+ irq = platform_get_irq(pdev,
+ shared_irq_index);
+ irq_flags = IRQF_SHARED;
+ } else {
+ irq = platform_get_irq(pdev, i);
+ irq_flags = 0;
+ }
- for (i = 0; i < pdev->num_resources; i++) {
- irq = platform_get_irq(pdev, i);
if (irq < 0)
break;
if (chans_available & (1 << i)) {
- rc = bcm2835_dma_chan_init(od, i, irq);
+ rc = bcm2835_dma_chan_init(od, i, irq, irq_flags);
if (rc)
goto err_no_dma;
}
--
2.1.4
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