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Commit c91134d9 authored by Robert Jarzmik's avatar Robert Jarzmik Committed by Vinod Koul
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dmaengine: pxa_dma: add support for legacy transition 



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: default avatarRobert Jarzmik <robert.jarzmik@free.fr>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarVinod Koul <vinod.koul@intel.com>
parent c01d1b51

drivers/dma/pxa_dma.c

+28 −0
Original line number Diff line number Diff line
@@ -410,6 +410,15 @@ 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;
@@ -430,10 +439,14 @@ 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;

			}

		}
@@ -453,6 +466,7 @@ 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__);
@@ -464,6 +478,9 @@ 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);
@@ -694,6 +711,8 @@ 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;

	}
@@ -1432,6 +1451,15 @@ 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");