Commit 50581cc4 authored by Linus Walleij's avatar Linus Walleij Committed by Stephen Boyd

clk: versatile add DT bindings for the ICST CM variants

The Integrator/AP and Integrator/CP core modules have special
versions of the ICST525 interface hardcoding some bits. Create
special compatible strings to identify these variants, also
explain a bit what is going on.

Cc: devicetree@vger.kernel.org
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Acked-by: default avatarRob Herring <robh@kernel.org>
Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
parent 62d15758
......@@ -5,20 +5,50 @@ Technology (IDT). ARM integrated these oscillators deeply into their
reference designs by adding special control registers that manage such
oscillators to their system controllers.
The ARM system controller contains logic to serialize and initialize
The various ARM system controllers contain logic to serialize and initialize
an ICST clock request after a write to the 32 bit register at an offset
into the system controller. Furthermore, to even be able to alter one of
these frequencies, the system controller must first be unlocked by
writing a special token to another offset in the system controller.
Some ARM hardware contain special versions of the serial interface that only
connects the low 8 bits of the VDW (missing one bit), hardwires RDW to
different values and sometimes also hardwire the output divider. They
therefore have special compatible strings as per this table (the OD value is
the value on the pins, not the resulting output divider):
Hardware variant: RDW OD VDW
Integrator/AP 22 1 Bit 8 0, rest variable
integratorap-cm
Integrator/AP 46 3 Bit 8 0, rest variable
integratorap-sys
Integrator/AP 22 or 1 17 or (33 or 25 MHz)
integratorap-pci 14 1 14
Integrator/CP 22 variable Bit 8 0, rest variable
integratorcp-cm-core
Integrator/CP 22 variable Bit 8 0, rest variable
integratorcp-cm-mem
The ICST oscillator must be provided inside a system controller node.
Required properties:
- compatible: must be one of
"arm,syscon-icst525"
"arm,syscon-icst307"
"arm,syscon-icst525-integratorap-cm"
"arm,syscon-icst525-integratorap-sys"
"arm,syscon-icst525-integratorap-pci"
"arm,syscon-icst525-integratorcp-cm-core"
"arm,syscon-icst525-integratorcp-cm-mem"
- lock-offset: the offset address into the system controller where the
unlocking register is located
- vco-offset: the offset address into the system controller where the
ICST control register is located (even 32 bit address)
- compatible: must be one of "arm,syscon-icst525" or "arm,syscon-icst307"
- #clock-cells: must be <0>
- clocks: parent clock, since the ICST needs a parent clock to derive its
frequency from, this attribute is compulsory.
......
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