Re: [PATCH v3] reset: add support for non-DT systems

[David Lechner]

On 02/19/2018 07:13 AM, Philipp Zabel wrote:
> Hi Bartosz,
>
> On Mon, 2018-02-19 at 13:34 +0100, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
> >
> > The reset framework only supports device-tree. There are some platforms
> > however, which need to use it even in legacy, board-file based mode.
> >
> > An example of such architecture is the DaVinci family of SoCs which
> > supports both device tree and legacy boot modes and we don't want to
> > introduce any regressions.
> >
> > We're currently working on converting the platform from its hand-crafted
> > clock API to using the common clock framework. Part of the overhaul will
> > be representing the chip's power sleep controller's reset lines using
> > the reset framework.
> >
> > This changeset extends the core reset code with a new field in the
> > reset controller struct which contains an array of lookup entries. Each
> > entry contains the device name, an additional, optional identifier
> > string and the reset id number.
> >
> > Drivers can register a set of reset lines using this lookup table and
> > concerned devices can access them using the regular reset_control API.
> >
> > This new function is only called as a fallback in case the of_node
> > field is NULL and doesn't change anything for current users.
> >
> > Tested with a dummy reset driver with several lookup entries.
> >
> > An example lookup table can look like this:
> >
> > static const struct reset_lookup foobar_reset_lookup[] = {
> > 	{ .dev = "foo",   .reset_id = "foo_id",    .id = 14 },
> > 	{ .dev = "bar",   .id = NULL,              .id = 3  },
> > 	{ }
> > };
>
> Thank you for the patch. This is a useful addition, but the lookups
> should be added in platform code, not by the reset controller driver.
>
> I would prefer reset_lookups to follow the patterns set by the other
> subsystem's lookup implementations:
> clk, gpiod, phy, and pwm have lookups that can be created from platform
> code, independently from the drivers (via clkdev_add_table,
> gpiod_add_lookup_table, phy_create_lookup, and pwm_add_table).
>
> Following this pattern would allow to support reset controllers that are
> implemented as proper device drivers, and reset controllers that are
> reused on multiple platforms.

When testing v2 of this series, I was thinking that having this sort
of separation would be better as well.