Lee, Arnd,
I had to make changes in this patch to address Rob's comments.
reg-io-width is now in bytes while bus-width was a value in bits. Could
you please review this patch ?
Thanks,
Damien
On Mon, Nov 30, 2015 at 01:00:15PM -0600, Rob Herring wrote:
> On Mon, Nov 30, 2015 at 10:59:47AM -0500, Damien Riegel wrote:
> > 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@xxxxxxxxxxxxxxxxxxxx>
>
> Acked-by: Rob Herring <robh@xxxxxxxxxx>
>
> > ---
> > Documentation/devicetree/bindings/mfd/syscon.txt | 4 ++++
> > drivers/mfd/syscon.c | 13 +++++++++++++
> > 2 files changed, 17 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/mfd/syscon.txt b/Documentation/devicetree/bindings/mfd/syscon.txt
> > index fe8150b..408f768 100644
> > --- a/Documentation/devicetree/bindings/mfd/syscon.txt
> > +++ b/Documentation/devicetree/bindings/mfd/syscon.txt
> > @@ -13,6 +13,10 @@ 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";
> > diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
> > index 176bf0f..b7aabee 100644
> > --- a/drivers/mfd/syscon.c
> > +++ b/drivers/mfd/syscon.c
> > @@ -47,6 +47,7 @@ static struct syscon *of_syscon_register(struct device_node *np)
> > struct syscon *syscon;
> > struct regmap *regmap;
> > void __iomem *base;
> > + u32 reg_io_width;
> > int ret;
> > struct regmap_config syscon_config = syscon_regmap_config;
> >
> > @@ -69,6 +70,18 @@ static struct syscon *of_syscon_register(struct device_node *np)
> > else if (of_property_read_bool(np, "little-endian"))
> > syscon_config.val_format_endian = REGMAP_ENDIAN_LITTLE;
> >
> > + /*
> > + * search for reg-io-width property in DT. If it is not provided,
> > + * default to 4 bytes. regmap_init_mmio will return an error if values
> > + * are invalid so there is no need to check them here.
> > + */
> > + ret = of_property_read_u32(np, "reg-io-width", ®_io_width);
> > + if (ret)
> > + reg_io_width = 4;
> > +
> > + syscon_config.reg_stride = reg_io_width;
> > + syscon_config.val_bits = reg_io_width * 8;
> > +
> > regmap = regmap_init_mmio(NULL, base, &syscon_config);
> > if (IS_ERR(regmap)) {
> > pr_err("regmap init failed\n");
> > --
> > 2.5.0
> >
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