Now, in Kernel, parent device's DMA parameters has to be applied to
the child as is - to enable DMA support for the device. Usually this
is happened in places where parent device manually instantiates child
device such as in drivers/pci/probe.c (pci_device_add() for example).
Now DMA configuration is represented in device data structure not only
by DMA mask and DMA params, it also includes dma_pfn_offset at least.
Hence introduce common dma_get_parent_cfg() helper to apply dma
configuration from parent to child, and use __weak to allow arch to
override it if needed.
Signed-off-by: Murali Karicheri <m-karicheri2@xxxxxx>
---
drivers/base/dma-mapping.c | 18 ++++++++++++++++++
include/linux/dma-mapping.h | 3 +++
2 files changed, 21 insertions(+)
diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c
index 9e8bbdd..5322426 100644
--- a/drivers/base/dma-mapping.c
+++ b/drivers/base/dma-mapping.c
@@ -339,3 +339,21 @@ void dma_common_free_remap(void *cpu_addr, size_t size, unsigned long vm_flags)
vunmap(cpu_addr);
}
#endif
+
+int __weak dma_get_parent_cfg(struct device *dev, struct device *parent)
+{
+ struct device *temp = parent;
+
+ if (!temp)
+ temp = dev->parent;
+
+ if (temp && is_device_dma_capable(temp)) {
+ dev->dma_mask = temp->dma_mask;
+ dev->coherent_dma_mask = temp->coherent_dma_mask;
+ dev->dma_parms = temp->dma_parms;
+ dev->dma_pfn_offset = temp->dma_pfn_offset;
+ return 0;
+ }
+ return -EINVAL;
+}
+EXPORT_SYMBOL(dma_get_parent_cfg);
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index d5d3881..eb080d6 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -127,6 +127,9 @@ static inline int dma_coerce_mask_and_coherent(struct device *dev, u64 mask)
return dma_set_mask_and_coherent(dev, mask);
}
+extern int __weak dma_get_parent_cfg(struct device *dev,
+ struct device *parent);
+
extern u64 dma_get_required_mask(struct device *dev);
#ifndef set_arch_dma_coherent_ops
--
1.7.9.5
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