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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: Robert Jarzmik <robert.jarzmik@free.fr>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This commit is contained in:
Robert Jarzmik 2015-05-25 23:29:22 +02:00 committed by Vinod Koul
parent c01d1b5159
commit c91134d919
1 changed files with 28 additions and 0 deletions
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28
drivers/dma/pxa_dma.c
View File

@ -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");