Create API to map between CPU physical and bus addresses
On some SoCs, DMA-capable peripherals see a different address space to the CPU's physical address space. Create an API to allow platform-agnostic drivers to convert between the two address spaces when programming DMA operations. This API will exist on all platforms, but will have a dummy implementation when this feature is not required. Other platforms will enable CONFIG_PHYS_TO_BUS and provide the required implementation. Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
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@ -53,3 +53,11 @@ source "drivers/crypto/Kconfig"
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source "drivers/thermal/Kconfig"
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source "drivers/thermal/Kconfig"
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endmenu
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endmenu
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config PHYS_TO_BUS
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bool
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help
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Some SoCs use a different address map for CPU physical addresses and
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peripheral DMA master accesses. If yours does, select this option in
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your platform's Kconfig, and implement the appropriate mapping
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functions in your platform's support code.
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@ -0,0 +1,25 @@
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/*
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* Copyright 2015 Stephen Warren
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*
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* SPDX-License-Identifier: GPL-2.0+
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*/
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#ifndef _BUS_ADDR_H
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#define _BUS_ADDR_H
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#ifdef CONFIG_PHYS_TO_BUS
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unsigned long phys_to_bus(unsigned long phys);
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unsigned long bus_to_phys(unsigned long bus);
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#else
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static inline unsigned long phys_to_bus(unsigned long phys)
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{
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return phys;
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}
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static inline unsigned long bus_to_phys(unsigned long bus)
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{
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return bus;
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}
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#endif
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#endif
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