Messages in this thread | | | Subject | Re: [PATCH v2] reset: add support for non-DT systems | From | David Lechner <> | Date | Fri, 16 Feb 2018 20:01:11 -0600 |
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On 02/13/2018 12:39 PM, Bartosz Golaszewski wrote: > From: Bartosz Golaszewski <bgolaszewski@baylibre.com> > > 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 and an additional, optional identifier > string. > > 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[] = { > [FOO_RESET] = { .dev = "foo", .id = "foo_id" }, > [BAR_RESET] = { .dev = "bar", .id = NULL }, > { } > }; > > where FOO_RESET and BAR_RESET will correspond with the id parameters > of reset callbacks. > > Cc: Sekhar Nori <nsekhar@ti.com> > Cc: Kevin Hilman <khilman@baylibre.com> > Cc: David Lechner <david@lechnology.com> > Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com> > --- > v1 -> v2: > - renamed the new function to __reset_control_get_from_lookup() > - added a missing break; when a matching entry is found > - rearranged the code in __reset_control_get() - we can no longer get to the > return at the bottom, so remove it and return from > __reset_control_get_from_lookup() if __of_reset_control_get() fails > - return -ENOENT from reset_contol_get() if we can't find a matching entry, > prevously returned -EINVAL referred to the fact that we passed a device > without the of_node which is no longer an error condition > - add a comment about needing a sentinel in the lookup table > > drivers/reset/core.c | 40 +++++++++++++++++++++++++++++++++++++++- > include/linux/reset-controller.h | 14 ++++++++++++++ > 2 files changed, 53 insertions(+), 1 deletion(-) > > diff --git a/drivers/reset/core.c b/drivers/reset/core.c > index da4292e9de97..b104a0c5c511 100644 > --- a/drivers/reset/core.c > +++ b/drivers/reset/core.c > @@ -493,6 +493,44 @@ struct reset_control *__of_reset_control_get(struct device_node *node, > } > EXPORT_SYMBOL_GPL(__of_reset_control_get); > > +static struct reset_control * > +__reset_control_get_from_lookup(struct device *dev, const char *id, > + bool shared, bool optional) > +{ > + struct reset_controller_dev *rcdev; > + const char *dev_id = dev_name(dev); > + struct reset_control *rstc = NULL; > + const struct reset_lookup *lookup; > + int index; > + > + mutex_lock(&reset_list_mutex); > + > + list_for_each_entry(rcdev, &reset_controller_list, list) { > + if (!rcdev->lookup) > + continue; > + > + lookup = rcdev->lookup; > + for (index = 0; lookup->dev; index++, lookup++) {> + if (strcmp(dev_id, lookup->dev)) > + continue; > + > + if ((!id && !lookup->id) || > + (id && lookup->id && !strcmp(id, lookup->id))) { > + rstc = __reset_control_get_internal(rcdev, > + index, shared); > + break; > + } > + } > + }
This method of determining the index is not very useful. In the case of the DSP reset on OMAP-L138, the index *must* be the LPSC module domain number, which is 15. This would require us to create 15 dummy entries in the rcdev->lookup array so that we get the correct index in order to get the correct reset control.
I think it would be better to just store the index in struct reset_lookup.
Another option would be to require the length of lookup to be rcdev->nr_resets instead of using a sentinel.
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