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of: reserved_mem: Accessor for acquiring reserved_mem

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In some cases drivers referencing a reserved-memory region might want to
remap the entire region, but when defining the reserved-memory by "size"
the client driver has no means to know the associated base address of
the reserved memory region.

This patch adds an accessor for such drivers to acquire a handle to
their associated reserved-memory for this purpose.

A complicating factor for the implementation is that the reserved_mem
objects are created from the flattened DeviceTree, as such we can't
use the device_node address for comparison. Fortunately the name of the
node will be used as "name" of the reserved_mem and will be used when
building the full_name, so we can compare the "name" with the basename
of the full_name to find the match.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>
This commit is contained in:
Bjorn Andersson
2017-10-10 22:08:54 -07:00
committed by Andy Gross
parent a50ff19d06
commit eb297bc716
2 changed files with 31 additions and 0 deletions
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26
drivers/of/of_reserved_mem.c
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@@ -397,3 +397,29 @@ void of_reserved_mem_device_release(struct device *dev)
rmem->ops->device_release(rmem, dev);
}
EXPORT_SYMBOL_GPL(of_reserved_mem_device_release);
/**
* of_reserved_mem_lookup() - acquire reserved_mem from a device node
* @np: node pointer of the desired reserved-memory region
*
* This function allows drivers to acquire a reference to the reserved_mem
* struct based on a device node handle.
*
* Returns a reserved_mem reference, or NULL on error.
*/
struct reserved_mem *of_reserved_mem_lookup(struct device_node *np)
{
const char *name;
int i;
if (!np->full_name)
return NULL;
name = kbasename(np->full_name);
for (i = 0; i < reserved_mem_count; i++)
if (!strcmp(reserved_mem[i].name, name))
return &reserved_mem[i];
return NULL;
}
EXPORT_SYMBOL_GPL(of_reserved_mem_lookup);