From 4b7f48d395a7e3b11ded7695ac2b36d0685e0785 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Wed, 9 Dec 2015 15:52:59 +0900 Subject: bus: uniphier-system-bus: add UniPhier System Bus driver The UniPhier System Bus is an external bus that connects on-board devices to the UniPhier SoC. Each bank (chip select) is dynamically mapped to the CPU-viewed address base via the bus controller. The bus controller must be configured before any access to the bus. This driver parses the "ranges" property of the System Bus node and initialized the bus controller. After the bus becomes ready, devices below it are populated. Note: Each bank can be mapped anywhere in the supported address space; there is nothing preventing us from assigning bank 0 on 0x42000000, 0x43000000, or anywhere as long as such region is not used by others. So, the "ranges" is just one possible software configuration, which does not seem to fit in device tree because device tree is a hardware description language. However, of_translate_address() requires "ranges" in every bus node between CPUs and device mapped on the CPU address space. In other words, "ranges" properties must be statically defined in device tree. After some discussion, I decided the dynamic address reassignment by the driver is too bothersome. Instead, the device tree should provide a reasonable translation setup that the OS can rely on. Signed-off-by: Masahiro Yamada Acked-by: Rob Herring Acked-by: Arnd Bergmann Signed-off-by: Olof Johansson --- drivers/bus/Kconfig | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'drivers/bus/Kconfig') diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig index 116b363b7987..9a92c072a485 100644 --- a/drivers/bus/Kconfig +++ b/drivers/bus/Kconfig @@ -131,6 +131,14 @@ config SUNXI_RSB with various RSB based devices, such as AXP223, AXP8XX PMICs, and AC100/AC200 ICs. +config UNIPHIER_SYSTEM_BUS + tristate "UniPhier System Bus driver" + depends on ARCH_UNIPHIER && OF + default y + help + Support for UniPhier System Bus, a simple external bus. This is + needed to use on-board devices connected to UniPhier SoCs. + config VEXPRESS_CONFIG bool "Versatile Express configuration bus" default y if ARCH_VEXPRESS -- cgit v1.2.3