Retrieve DMA configuration from DT and setup platform device's DMA
parameters. The DMA configuration in DT has to be specified using
"dma-ranges" and "dma-coherent" properties if supported.

We setup dma_pfn_offset using "dma-ranges" and dma_coherent_ops
using "dma-coherent" device tree properties.

The set_arch_dma_coherent_ops macro has to be defined by arch if
it supports coherent dma_ops. Otherwise, set_arch_dma_coherent_ops() is
declared as nop.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Russell King <redacted>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Olof Johansson <redacted>
Cc: Grant Likely <redacted>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Walleij <redacted>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Santosh Shilimkar <redacted>
---
 drivers/of/platform.c       |   48 ++++++++++++++++++++++++++++++++++++++++---
 include/linux/dma-mapping.h |    7 +++++++
 2 files changed, 52 insertions(+), 3 deletions(-)

diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 48de98f..270c0b9 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c

@@ -187,6 +187,50 @@ struct platform_device *of_device_alloc(struct device_node *np,
 EXPORT_SYMBOL(of_device_alloc);
 
 /**
+ * of_dma_configure - Setup DMA configuration
+ * @dev:	Device to apply DMA configuration
+ *
+ * Try to get devices's DMA configuration from DT and update it
+ * accordingly.
+ *
+ * In case if platform code need to use own special DMA configuration,it
+ * can use Platform bus notifier and handle BUS_NOTIFY_ADD_DEVICE event
+ * to fix up DMA configuration.
+ */
+static void of_dma_configure(struct device *dev)
+{
+	u64 dma_addr, paddr, size;
+	int ret;
+
+	dev->coherent_dma_mask = DMA_BIT_MASK(32);
+	if (!dev->dma_mask)
+		dev->dma_mask = &dev->coherent_dma_mask;
+
+	/*
+	 * if dma-coherent property exist, call arch hook to setup
+	 * dma coherent operations.
+	 */
+	if (of_dma_is_coherent(dev->of_node)) {
+		set_arch_dma_coherent_ops(dev);
+		dev_dbg(dev, "device is dma coherent\n");
+	}
+
+	/*
+	 * if dma-ranges property doesn't exist - just return else
+	 * setup the dma offset
+	 */
+	ret = of_dma_get_range(dev->of_node, &dma_addr, &paddr, &size);
+	if ((ret == -ENODEV) || (ret < 0)) {
+		dev_dbg(dev, "no dma range information to setup\n");
+		return;
+	}
+
+	/* DMA ranges found. Calculate and set dma_pfn_offset */
+	dev->dma_pfn_offset = PFN_DOWN(paddr - dma_addr);
+	dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", dev->dma_pfn_offset);