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 --- These patches depend on previous DWC2 rework that's in the topic/dwc2 branch of the USB repo.
These patches conflict with patches Masahiro has posted to move arch/arm/cpu/arm1176/bcm2835 to arch/arm/mach-bcm283x(?).
I expect I'll have to rebase this series after the upcoming release once those two things are merged into u-boot.git. Still, reviews could begin before that. --- drivers/Kconfig | 8 ++++++++ include/phys2bus.h | 25 +++++++++++++++++++++++++ 2 files changed, 33 insertions(+) create mode 100644 include/phys2bus.h
diff --git a/drivers/Kconfig b/drivers/Kconfig index dcce532e2df2..941aa0c2612a 100644 --- a/drivers/Kconfig +++ b/drivers/Kconfig @@ -53,3 +53,11 @@ source "drivers/crypto/Kconfig" source "drivers/thermal/Kconfig"
endmenu + +config PHYS_TO_BUS + bool + help + Some SoCs use a different address map for CPU physical addresses and + peripheral DMA master accesses. If yours does, select this option in + your platform's Kconfig, and implement the appropriate mapping + functions in your platform's support code. diff --git a/include/phys2bus.h b/include/phys2bus.h new file mode 100644 index 000000000000..87b6d69aa617 --- /dev/null +++ b/include/phys2bus.h @@ -0,0 +1,25 @@ +/* + * Copyright 2015 Stephen Warren + * + * SPDX-License-Identifier: GPL-2.0+ + */ + +#ifndef _BUS_ADDR_H +#define _BUS_ADDR_H + +#ifdef CONFIG_PHYS_TO_BUS +unsigned long phys_to_bus(unsigned long phys); +unsigned long bus_to_phys(unsigned long bus); +#else +static inline unsigned long phys_to_bus(unsigned long phys) +{ + return phys; +} + +static inline unsigned long bus_to_phys(unsigned long bus) +{ + return bus; +} +#endif + +#endif