On all Exynos SoCs there is a dedicated CLKOUT pin that allows many of
internal SoC clocks to be output from the SoC. The hardware structure
of CLKOUT related clocks looks as follows:
CMU |---> clock0 ---------> | PMU |
| | |
several |---> clock1 ---------> | mux |
muxes | | + |---> CLKOUT
dividers | ... | gate |
and gates | | |
|---> clockN ---------> | |
Since the block responsible for handling the pin is PMU, not CMU,
a separate driver, that binds to PMU node is required and acquires
all input clocks by standard DT clock look-up. This way we don't need
any cross-IP block drivers and cross-driver register sharing or
nodes for fake devices.
To represent the PMU mux/gate clock, generic composite clock is registered.
Tested on Odroid U3, with HSIC/USB hub using CLKOUT as reference clock,
with some additional patches.
Changes since v1:
(http://www.spinics.net/lists/arm-kernel/msg333276.html)
- rebased onto next-20140624,
- fixed #clock-cells values in exynos5250.dtsi and exynos5420.dtsi,
- temporarily removed ISP CLKOUT clocks on Exynos4x12, until ISP clock
domain handling gets fixed in Exynos4 clock driver.
Changes since RFC v1:
(https://lkml.org/lkml/2014/5/15/506)
- rebased onto v5 of "Enable usbphy and hsotg for exynos4" series and
current HEAD of samsung-clk tree,
- added handling of suspend/resume in the driver,
- added missing CPU clocks on Exynos4,
- added CLK_SET_RATE_PARENT to CMU CLKOUT gates on Exynos4,
- fixed bit field width on Exynos4,
- added CLKOUT CMU registers of Exynos4 to save/restore list,
- added CLK_SET_RATE_PARENT and CLK_SET_RATE_NO_REPARENT to clkout clock,
- changed the binding to use 1-cell clock specifier to allow extension
with further PMU clocks in future, if needed.
Tomasz Figa (4):
clk: samsung: exynos4: Add missing CPU/DMC clock hierarchy
clk: samsung: exynos4: Add CLKOUT clock hierarchy
clk: samsung: Add driver to control CLKOUT line on Exynos SoCs
ARM: dts: exynos: Update PMU node with CLKOUT related data
.../devicetree/bindings/arm/samsung/pmu.txt | 30 ++++
arch/arm/boot/dts/exynos4210.dtsi | 10 ++
arch/arm/boot/dts/exynos4x12.dtsi | 7 +
arch/arm/boot/dts/exynos5250.dtsi | 3 +
arch/arm/boot/dts/exynos5420.dtsi | 3 +
drivers/clk/samsung/Makefile | 1 +
drivers/clk/samsung/clk-exynos-clkout.c | 153 +++++++++++++++++++
drivers/clk/samsung/clk-exynos4.c | 166 ++++++++++++++++++++-
include/dt-bindings/clock/exynos4.h | 5 +
9 files changed, 374 insertions(+), 4 deletions(-)
create mode 100644 drivers/clk/samsung/clk-exynos-clkout.c
--
1.9.3
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