Re: [PATCH v3] reset: add support for non-DT systems
From: Philipp Zabel
Date: Mon Feb 19 2018 - 08:13:33 EST
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.
regards
Philipp