[PoC] arm: dma-mapping: direct: Apply dma_pfn_offset only when it is valid

[Peter Ujfalusi <peter.ujfalusi@ti.com>]

The dma_pfn_offset should only be applied to an address which is within the
dma-ranges range. Any address outside should have offset as 0.

This is a proof of concept patch which works on k2g where we have
dma-ranges = <0x80000000 0x8 0x00000000 0x80000000>;
for the SoC.

Without this patch everything which tries to set DMA_BIT_MASK(32) or less
fails -> DMA and peripherals with built in DMA (SD with ADMA) will not
probe or fall back to PIO mode.

With this patch EDMA probes, SD's ADMA is working.
Audio and dma-test is working just fine with EDMA, mmc accesses with ADMA
also operational.

The patch does not tried to address the incomplete handling of dma-ranges
from DT and it is not fixing/updating arch code or drivers which uses
dma_pfn_offset.
Neither provides fallback support for kernel setting only dma_pfn_offset to
arbitrary number without paddr/dma_addr/size.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
---
Hi Christoph, Robin,

I know it is a bit more complicated, but with this patch k2g is working fine...

I wanted to test the concept I was describing and a patch speaks better than
words.

Kind regards,
Peter

 arch/arm/include/asm/dma-mapping.h | 25 ++++++++++++++++++++--
 drivers/of/device.c                |  7 ++++++-
 include/linux/device.h             |  8 ++++++++
 include/linux/dma-direct.h         | 33 ++++++++++++++++++++++++++++--
 kernel/dma/coherent.c              |  9 +++++---
 5 files changed, 74 insertions(+), 8 deletions(-)

diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
index bdd80ddbca34..9bff6ad2d8c8 100644
--- a/arch/arm/include/asm/dma-mapping.h
+++ b/arch/arm/include/asm/dma-mapping.h
@@ -33,10 +33,31 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
  * addresses. They must not be used by drivers.
  */
 #ifndef __arch_pfn_to_dma
+
+static inline unsigned long __phys_to_dma_pfn_offset(struct device *dev,
+						     phys_addr_t paddr)
+{
+	if (paddr >= dev->dma_ranges.paddr &&
+	    paddr <= (dev->dma_ranges.paddr + dev->dma_ranges.size))
+		return dev->dma_ranges.pfn_offset;
+
+	return 0;
+}
+
+static inline unsigned long __dma_to_phys_pfn_offset(struct device *dev,
+						     dma_addr_t dma_addr)
+{
+	if (dma_addr >= dev->dma_ranges.dma_addr &&
+	    dma_addr <= (dev->dma_ranges.dma_addr + dev->dma_ranges.size))
+		return dev->dma_ranges.pfn_offset;
+
+	return 0;
+}
+
 static inline dma_addr_t pfn_to_dma(struct device *dev, unsigned long pfn)
 {
 	if (dev)
-		pfn -= dev->dma_pfn_offset;
+		pfn -= __phys_to_dma_pfn_offset(dev, __pfn_to_phys(pfn));
 	return (dma_addr_t)__pfn_to_bus(pfn);
 }
 
@@ -45,7 +66,7 @@ static inline unsigned long dma_to_pfn(struct device *dev, dma_addr_t addr)
 	unsigned long pfn = __bus_to_pfn(addr);
 
 	if (dev)
-		pfn += dev->dma_pfn_offset;
+		pfn += __dma_to_phys_pfn_offset(dev, addr);
 
 	return pfn;
 }
diff --git a/drivers/of/device.c b/drivers/of/device.c
index 27203bfd0b22..07a8cc1a7d7f 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -105,7 +105,7 @@ int of_dma_configure(struct device *dev, struct device_node *np, bool force_dma)
 		if (!force_dma)
 			return ret == -ENODEV ? 0 : ret;
 
-		dma_addr = offset = 0;
+		dma_addr = offset = paddr = 0;
 	} else {
 		offset = PFN_DOWN(paddr - dma_addr);
 
@@ -144,6 +144,11 @@ int of_dma_configure(struct device *dev, struct device_node *np, bool force_dma)
 
 	dev->dma_pfn_offset = offset;
 
+	dev->dma_ranges.paddr = paddr;
+	dev->dma_ranges.dma_addr = dma_addr;
+	dev->dma_ranges.size = size;
+	dev->dma_ranges.pfn_offset = offset;
+
 	/*
 	 * Limit coherent and dma mask based on size and default mask
 	 * set by the driver.
diff --git a/include/linux/device.h b/include/linux/device.h
index ce6db68c3f29..57006b51a989 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -293,6 +293,13 @@ struct device_dma_parameters {
 	unsigned long segment_boundary_mask;
 };
 
+struct dma_ranges {
+	u64 paddr;
+	u64 dma_addr;
+	u64 size;
+	unsigned long pfn_offset;
+};
+
 /**
  * struct device_connection - Device Connection Descriptor
  * @fwnode: The device node of the connected device
@@ -581,6 +588,7 @@ struct device {
 					     allocations such descriptors. */
 	u64		bus_dma_limit;	/* upstream dma constraint */
 	unsigned long	dma_pfn_offset;
+	struct dma_ranges dma_ranges;
 
 	struct device_dma_parameters *dma_parms;
 
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index 24b8684aa21d..4a46a15945ea 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -11,18 +11,47 @@ extern unsigned int zone_dma_bits;
 #ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA
 #include <asm/dma-direct.h>
 #else
+
+static inline unsigned long __phys_to_dma_pfn_offset(struct device *dev,
+						     phys_addr_t paddr)
+{
+	if (!dev)
+		return 0;
+
+	if (paddr >= dev->dma_ranges.paddr &&
+	    paddr <= (dev->dma_ranges.paddr + dev->dma_ranges.size))
+		return dev->dma_ranges.pfn_offset
+
+	return 0;
+}
+
+static inline unsigned long __dma_to_phys_pfn_offset(struct device *dev,
+						     dma_addr_t dma_addr)
+{
+	if (!dev)
+		return 0;
+
+	if (dma_addr >= dev->dma_ranges.dma_addr &&
+	    dma_addr <= (dev->dma_ranges.dma_addr + dev->dma_ranges.size))
+		return dev->dma_ranges.pfn_offset
+
+	return 0;
+}
+
 static inline dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)
 {
 	dma_addr_t dev_addr = (dma_addr_t)paddr;
+	unsigned long offset = __phys_to_dma_pfn_offset(dev, paddr);
 
-	return dev_addr - ((dma_addr_t)dev->dma_pfn_offset << PAGE_SHIFT);
+	return dev_addr - ((dma_addr_t)offset << PAGE_SHIFT);
 }
 
 static inline phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t dev_addr)
 {
 	phys_addr_t paddr = (phys_addr_t)dev_addr;
+	unsigned long offset = __dma_to_phys_pfn_offset(dev, dev_addr);
 
-	return paddr + ((phys_addr_t)dev->dma_pfn_offset << PAGE_SHIFT);
+	return paddr + ((phys_addr_t)offset << PAGE_SHIFT);
 }
 #endif /* !CONFIG_ARCH_HAS_PHYS_TO_DMA */
 
diff --git a/kernel/dma/coherent.c b/kernel/dma/coherent.c
index 551b0eb7028a..7a68fd09f5d0 100644
--- a/kernel/dma/coherent.c
+++ b/kernel/dma/coherent.c
@@ -31,10 +31,13 @@ static inline struct dma_coherent_mem *dev_get_coherent_memory(struct device *de
 static inline dma_addr_t dma_get_device_base(struct device *dev,
 					     struct dma_coherent_mem * mem)
 {
-	if (mem->use_dev_dma_pfn_offset)
-		return (mem->pfn_base - dev->dma_pfn_offset) << PAGE_SHIFT;
-	else
+	if (mem->use_dev_dma_pfn_offset) {
+		unsigned long offset = __phys_to_dma_pfn_offset(dev,
+						__pfn_to_phys(mem->pfn_base));
+		return (mem->pfn_base - offset) << PAGE_SHIFT;
+	} else {
 		return mem->device_base;
+	}
 }
 
 static int dma_init_coherent_memory(phys_addr_t phys_addr,
-- 
Peter

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