linux_dsm_epyc7002/Documentation/devicetree/bindings/mfd/syscon.txt
Damien Riegel db2fb60cd3 mfd: syscon: Add a DT property to set value width
Currently syscon has a fixed configuration of 32 bits for register and
values widths. In some cases, it would be desirable to be able to
customize the value width.

For example, certain boards (like the ones manufactured by Technologic
Systems) have a FPGA that is memory-mapped, but its registers are only
16-bit wide.

This patch adds an optional "reg-io-width" DT binding for syscon that
allows to change the width for the data bus (i.e. val_bits). If this
property is provided, it will also set the register stride to
reg-io-width's value. If not provided, the default configuration is
used.

Signed-off-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
2016-01-11 06:08:02 +00:00

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* System Controller Registers R/W driver
System controller node represents a register region containing a set
of miscellaneous registers. The registers are not cohesive enough to
represent as any specific type of device. The typical use-case is for
some other node's driver, or platform-specific code, to acquire a
reference to the syscon node (e.g. by phandle, node path, or search
using a specific compatible value), interrogate the node (or associated
OS driver) to determine the location of the registers, and access the
registers directly.
Required properties:
- compatible: Should contain "syscon".
- reg: the register region can be accessed from syscon
Optional property:
- reg-io-width: the size (in bytes) of the IO accesses that should be
performed on the device.
Examples:
gpr: iomuxc-gpr@020e0000 {
compatible = "fsl,imx6q-iomuxc-gpr", "syscon";
reg = <0x020e0000 0x38>;
};