In order to achieve smooth transition of pxa drivers from old legacy dma
handling to new dmaengine, introduce a function to "hide" dma physical
channels from dmaengine.
This is temporary situation where pxa dma will be handled in 2 places :
- arch/arm/plat-pxa/dma.c
- drivers/dma/pxa_dma.c
The resources, ie. dma channels, will be controlled by pxa_dma. The
legacy code will request or release a channel with
pxad_toggle_reserved_channel().
This is not very pretty, but it ensures both legacy and dmaengine
consumers can live in the same kernel until the conversion is done.
Signed-off-by: Robert Jarzmik <robert.jarzmik@xxxxxxx>
---
drivers/dma/pxa_dma.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c
index f0912a2..08abb51 100644
--- a/drivers/dma/pxa_dma.c
+++ b/drivers/dma/pxa_dma.c
@@ -408,6 +408,15 @@ static inline void pxad_init_debugfs(struct pxad_device *pdev) {}
static inline void pxad_cleanup_debugfs(struct pxad_device *pdev) {}
#endif
+/*
+ * In the transition phase where legacy pxa handling is done at the same time as
+ * mmp_dma, the DMA physical channel split between the 2 DMA providers is done
+ * through legacy_reserved. Legacy code reserves DMA channels by settings
+ * corresponding bits in legacy_reserved.
+ */
+static u32 legacy_reserved;
+static u32 legacy_unavailable;
+
static struct pxad_phy *lookup_phy(struct pxad_chan *pchan)
{
int prio, i;
@@ -428,10 +437,14 @@ static struct pxad_phy *lookup_phy(struct pxad_chan *pchan)
for (i = 0; i < pdev->nr_chans; i++) {
if (prio != (i & 0xf) >> 2)
continue;
+ if ((i < 32) && (legacy_reserved & BIT(i)))
+ continue;
phy = &pdev->phys[i];
if (!phy->vchan) {
phy->vchan = pchan;
found = phy;
+ if (i < 32)
+ legacy_unavailable |= BIT(i);
goto out_unlock;
}
}
@@ -451,6 +464,7 @@ static void pxad_free_phy(struct pxad_chan *chan)
struct pxad_device *pdev = to_pxad_dev(chan->vc.chan.device);
unsigned long flags;
u32 reg;
+ int i;
dev_dbg(&chan->vc.chan.dev->device,
"%s(): freeing\n", __func__);
@@ -462,6 +476,9 @@ static void pxad_free_phy(struct pxad_chan *chan)
writel_relaxed(0, chan->phy->base + reg);
spin_lock_irqsave(&pdev->phy_lock, flags);
+ for (i = 0; i < 32; i++)
+ if (chan->phy == &pdev->phys[i])
+ legacy_unavailable &= ~BIT(i);
chan->phy->vchan = NULL;
chan->phy = NULL;
spin_unlock_irqrestore(&pdev->phy_lock, flags);
@@ -691,6 +708,8 @@ static irqreturn_t pxad_int_handler(int irq, void *dev_id)
i = __ffs(dint);
dint &= (dint - 1);
phy = &pdev->phys[i];
+ if ((i < 32) && (legacy_reserved & BIT(i)))
+ continue;
if (pxad_chan_handler(irq, phy) == IRQ_HANDLED)
ret = IRQ_HANDLED;
}
@@ -1429,6 +1448,15 @@ bool pxad_filter_fn(struct dma_chan *chan, void *param)
}
EXPORT_SYMBOL_GPL(pxad_filter_fn);
+int pxad_toggle_reserved_channel(int legacy_channel)
+{
+ if (legacy_unavailable & (BIT(legacy_channel)))
+ return -EBUSY;
+ legacy_reserved ^= BIT(legacy_channel);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(pxad_toggle_reserved_channel);
+
module_platform_driver(pxad_driver);
MODULE_DESCRIPTION("Marvell PXA Peripheral DMA Driver");
--
2.1.4
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