Am Donnerstag, den 27.07.2017, 07:00 +0200 schrieb Oleksij Rempel:
> > commit 37786c7fee40771d13901de129af7e084ed48b55
> > Author: Kevin Cernekee <cernekee@xxxxxxxxx>
> > Date: Thu Apr 9 13:05:14 2015 -0700
> >
> > of: Add helper function to check MMIO register endianness
> >
> > SoC peripherals can come in several different flavors:
> >
> > - little-endian: registers always need to be accessed in LE
> > mode (so the
> > kernel should perform a swap if the CPU is running BE)
> >
> > - big-endian: registers always need to be accessed in BE mode
> > (so the
> > kernel should perform a swap if the CPU is running LE)
> >
> > - native-endian: the bus will automatically swap accesses, so
> > the kernel
> > should never swap
> >
> > Introduce a function that checks an OF device node to see
> > whether it
> > contains a "big-endian" or "native-endian" property. For the
> > former case,
> > always return true. For the latter case, return true iff the
> > kernel was
> > built for BE (implying that the BE MMIO accessors do not perform
> > a swap).
> > Otherwise return false, assuming LE registers.
> >
> > LE registers are assumed by default because most existing
> > drivers (libahci,
> > serial8250, usb) always use readl/writel in the absence of
> > instructions
> > to the contrary, so that will be our fallback.
>
> Signed-off-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
I guess this should be your private mail address?
> ---
> drivers/of/base.c | 23 +++++++++++++++++++++++
> include/of.h | 1 +
> 2 files changed, 24 insertions(+)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index ea330d1310..95bea4ee83 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -1622,6 +1622,29 @@ int of_device_is_available(const struct
> device_node *device)
> EXPORT_SYMBOL(of_device_is_available);
>
> /**
> + * of_device_is_big_endian - check if a device has BE registers
> + *
> + * @device: Node to check for endianness
> + *
> + * Returns true if the device has a "big-endian" property, or if
> the kernel
> + * was compiled for BE *and* the device has a "native-endian"
> property.
> + * Returns false otherwise.
> + *
> + * Callers would nominally use ioread32be/iowrite32be if
> + * of_device_is_big_endian() == true, or readl/writel otherwise.
> + */
> +bool of_device_is_big_endian(const struct device_node *device)
> +{
> + if (of_property_read_bool(device, "big-endian"))
> + return true;
> + if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) &&
> + of_property_read_bool(device, "native-endian"))
> + return true;
> + return false;
> +}
> +EXPORT_SYMBOL(of_device_is_big_endian);
> +
> +/**
> * of_get_parent - Get a node's parent if any
> * @node: Node to get parent
> *
> diff --git a/include/of.h b/include/of.h
> index 0ba73f197f..4563cbeddd 100644
> --- a/include/of.h
> +++ b/include/of.h
> @@ -150,6 +150,7 @@ extern int of_machine_is_compatible(const char
> *compat);
> extern int of_device_is_compatible(const struct device_node *device,
> const char *compat);
> extern int of_device_is_available(const struct device_node *device);
> +extern bool of_device_is_big_endian(const struct device_node
> *device);
This misses a stub implementation for !CONFIG_OFTREE
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