Commit graph

4 commits

Author SHA1 Message Date
Simon Glass
a4b10c088c dm: clk: Add a simple version of clk_get_by_index()
This function adds quite a bit of code to SPL and we probably don't need
all the features in SPL. Add a simple version (for SPL only) to save space.

Signed-off-by: Simon Glass <sjg@chromium.org>
2016-01-21 20:42:35 -07:00
Simon Glass
e70cc43831 dm: clk: Add support for decoding clocks from the device tree
Add a method which can locate a clock for a device, given its index. This
uses the normal device tree bindings to return the clock device and the
first argument which is normally used as a peripheral ID in U-Boot.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2016-01-21 19:47:29 -07:00
Masahiro Yamada
f0e075162f clk: add API to enable clock
The most basic thing for clock is to enable it, but it is missing
in this uclass.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Simon Glass <sjg@chromium.org>
2016-01-20 19:06:23 -07:00
Simon Glass
f26c8a8e77 dm: Add a clock uclass
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>
2015-07-21 17:39:29 -06:00