dmaengine: idma64: Use actual device for DMA transfers

Intel IOMMU, when enabled, tries to find the domain of the device,
assuming it's a PCI one, during DMA operations, such as mapping or
unmapping. Since we are splitting the actual PCI device to couple of
children via MFD framework (see drivers/mfd/intel-lpss.c for details),
the DMA device appears to be a platform one, and thus not an actual one
that performs DMA. In a such situation IOMMU can't find or allocate
a proper domain for its operations. As a result, all DMA operations are
failed.

In order to fix this, supply parent of the platform device
to the DMA engine framework and fix filter functions accordingly.

We may rely on the fact that parent is a real PCI device, because no
other configuration is present in the wild.

Signed-off-by: Andy Shevchenko <[e-mail]>
Acked-by: Mark Brown <[e-mail]>
Acked-by: Greg Kroah-Hartman <[e-mail]> [for tty parts]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/idma64.c

···
 	idma64->dma.directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
 	idma64->dma.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
 
-	idma64->dma.dev = chip->dev;
+	idma64->dma.dev = chip->sysdev;
 
 	dma_set_max_seg_size(idma64->dma.dev, IDMA64C_CTLH_BLOCK_TS_MASK);
 
···
 {
 	struct idma64_chip *chip;
 	struct device *dev = &pdev->dev;
+	struct device *sysdev = dev->parent;
 	struct resource *mem;
 	int ret;
 
···
 	if (IS_ERR(chip->regs))
 		return PTR_ERR(chip->regs);
 
-	ret = dma_coerce_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
+	ret = dma_coerce_mask_and_coherent(sysdev, DMA_BIT_MASK(64));
 	if (ret)
 		return ret;
 
 	chip->dev = dev;
+	chip->sysdev = sysdev;
 
 	ret = idma64_probe(chip);
 	if (ret)

drivers/dma/idma64.h

···
 /**
  * struct idma64_chip - representation of iDMA 64-bit controller hardware
  * @dev:		struct device of the DMA controller
+ * @sysdev:		struct device of the physical device that does DMA
  * @irq:		irq line
  * @regs:		memory mapped I/O space
  * @idma64:		struct idma64 that is filed by idma64_probe()
  */
 struct idma64_chip {
 	struct device	*dev;
+	struct device	*sysdev;
 	int		irq;
 	void __iomem	*regs;
 	struct idma64	*idma64;

drivers/spi/spi-pxa2xx.c

···
 
 static bool pxa2xx_spi_idma_filter(struct dma_chan *chan, void *param)
 {
-	struct device *dev = param;
-
-	if (dev != chan->device->dev->parent)
-		return false;
-
-	return true;
+	return param == chan->device->dev;
 }
 
 #endif /* CONFIG_PCI */

drivers/tty/serial/8250/8250_dw.c

···
 
 static bool dw8250_idma_filter(struct dma_chan *chan, void *param)
 {
-	return param == chan->device->dev->parent;
+	return param == chan->device->dev;
 }
 
 /*
···
 		data->uart_16550_compatible = true;
 	}
 
-	/* Platforms with iDMA */
+	/* Platforms with iDMA 64-bit */
 	if (platform_get_resource_byname(to_platform_device(p->dev),
 					 IORESOURCE_MEM, "lpss_priv")) {
 		data->dma.rx_param = p->dev->parent;