[U-Boot] [PATCH] of-platdata: improve documentation

Simon Goldschmidt
2019-01-11T07:35:16Z

On Thu, Jan 10, 2019 at 1:57 PM Simon Glass <sjg@chromium.org> wrote:
>
> On Mon, 7 Jan 2019 at 12:23, Simon Goldschmidt
> <simon.k.r.goldschmidt@gmail.com> wrote:
> >
> > Improve some things in the documentation of OF_PLATDATA that I found
> > while porting socfgpa_gen5 to it.
> >
> > Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
> > ---
> >
> > doc/driver-model/of-plat.txt | 18 ++++++++++++------
> > dts/Kconfig | 6 ++----
> > 2 files changed, 14 insertions(+), 10 deletions(-)
>
> Reviewed-by: Simon Glass <sjg@chromium.org>
>
> >
> > diff --git a/doc/driver-model/of-plat.txt b/doc/driver-model/of-plat.txt
> > index 732bc34f06..ecb5f1724b 100644
> > --- a/doc/driver-model/of-plat.txt
> > +++ b/doc/driver-model/of-plat.txt
> > @@ -69,12 +69,12 @@ How it works
> > ------------
> >
> > The feature is enabled by CONFIG SPL_OF_PLATDATA. This is only available
> > -in SPL and should be tested with:
> > +in SPL/TPL and should be tested with:
> >
> > #if CONFIG_IS_ENABLED(SPL_OF_PLATDATA)
>
> Actually that seems wrong. Shouldn't it omit the SPL_ part?

Right, didn't catch that.

> >
> > A new tool called 'dtoc' converts a device tree file either into a set of
> > -struct declarations, one for each compatible node, or a set of
> > +struct declarations, one for each compatible node, and a set of
> > U_BOOT_DEVICE() declarations along with the actual platform data for each
> > device. As an example, consider this MMC node:
> >
> > @@ -156,6 +156,12 @@ This avoids the code overhead of converting the device tree data to
> > platform data in the driver. The ofdata_to_platdata() method should
> > therefore do nothing in such a driver.
> >
> > +Note that for the platform data to be matched with a driver, the 'name'
> > +property of the U_BOOT_DEVICE() declaration has to match a driver declared
> > +via U_BOOT_DRIVER(). This effectively means that a U_BOOT_DRIVER() with a
> > +'name' identical to the devicetree 'compatible' string is needed, so a
> > +dedicated driver is required for each 'compatible' string.
>
> Not identical - e.g. hyphens change to underscores.

Ehrm, yeah. Seems like I need a V2...

> > +
> > Where a node has multiple compatible strings, a #define is used to make them
> > equivalent, e.g.:
> >
> > @@ -165,8 +171,8 @@ equivalent, e.g.:
> > Converting of-platdata to a useful form
> > ---------------------------------------
> >
> > -Of course it would be possible use the of-platdata directly in your driver
> > -whenever configuration information is required. However this meands that the
> > +Of course it would be possible to use the of-platdata directly in your driver
> > +whenever configuration information is required. However this means that the
> > driver will not be able to support device tree, since the of-platdata
> > structure is not available when device tree is used. It would make no sense
> > to use this structure if device tree were available, since the structure has
> > @@ -282,8 +288,8 @@ prevents them being used inadvertently. All usage must be bracketed with
> > The dt-platdata.c file contains the device declarations and is is built in
> > spl/dt-platdata.c.
> >
> > -Some phandles (thsoe that are recognised as such) are converted into
> > -points to platform data. This pointer can potentially be used to access the
> > +Some phandles (those that are recognised as such) are converted into
> > +pointer to platform data. This pointer can potentially be used to access the
>
> a pointer to platform data

I'll change that as well in V2.

Regards,
Simon

>
> > referenced device (by searching for the pointer value). This feature is not
> > yet implemented, however.
> >
> > diff --git a/dts/Kconfig b/dts/Kconfig
> > index 8917f42444..3e85914d11 100644
> > --- a/dts/Kconfig
> > +++ b/dts/Kconfig
> > @@ -265,8 +265,7 @@ config SPL_OF_PLATDATA
> >
> > This option works by generating C structure declarations for each
> > compatible string, then adding platform data and U_BOOT_DEVICE
> > - declarations for each node. See README.platdata for more
> > - information.
> > + declarations for each node. See of-plat.txt for more information.
> >
> > config TPL_OF_PLATDATA
> > bool "Generate platform data for use in TPL"
> > @@ -287,8 +286,7 @@ config TPL_OF_PLATDATA
> >
> > This option works by generating C structure declarations for each
> > compatible string, then adding platform data and U_BOOT_DEVICE
> > - declarations for each node. See README.platdata for more
> > - information.
> > + declarations for each node. See of-plat.txt for more information.
> >
> > endmenu
> >
> > --
> > 2.17.1
> >