f26c8a8e77
Clocks are an important feature of platforms and have become increasing complex with time. Most modern SoCs have multiple PLLs and dozens of clock dividers which distribute clocks to on-chip peripherals. Some SoC implementations have a clock API which is private to that SoC family, e.g. Tegra and Exynos. This is useful but it would be better to have a common API that can be understood and used throughout U-Boot. Add a simple clock API as a starting point. It supports querying and setting the rate of a clock. Each clock is a device. To reduce memory and processing overhead the concept of peripheral clocks is provided. These do not need to be explicit devices - it is possible to write a driver that can adjust the I2C clock (for example) without an explicit I2C clock device. This can dramatically reduce the number of devices (and associated overhead) in a complex SoC. Clocks are referenced by a number, and it is expected that SoCs will define that numbering themselves via an enum. Signed-off-by: Simon Glass <sjg@chromium.org>
8 lines
171 B
Makefile
8 lines
171 B
Makefile
#
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# Copyright (c) 2015 Google, Inc
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# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
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#
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# SPDX-License-Identifier: GPL-2.0+
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#
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obj-$(CONFIG_CLK) += clk-uclass.o
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