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SubjectRe: [PATCH] reset: add support for non-DT systems
2018-02-13 18:17 GMT+01:00 David Lechner <david@lechnology.com>:
> On 02/13/2018 09:25 AM, 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>
>> ---
>
>
> Looks good to me. I just made a few very minor comments. I will
> try to use this in PSC driver later today.
>

Cool, if it works for you - feel free to include it in your series.

>
>> drivers/reset/core.c | 43
>> ++++++++++++++++++++++++++++++++++++++--
>> include/linux/reset-controller.h | 13 ++++++++++++
>> 2 files changed, 54 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/reset/core.c b/drivers/reset/core.c
>> index da4292e9de97..ba7011c6e06f 100644
>> --- a/drivers/reset/core.c
>> +++ b/drivers/reset/core.c
>> @@ -493,12 +493,51 @@ 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_lookup(struct device *dev, const char *id,
>
>
> Based on the name of the function, I expected this to return
> struct reset_lookup. Perhaps __reset_control_lookup() or
> __reset_control_match_lookup() would be a slightly better name?
>
>
>> + 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);

Ugh, I noticed that this needs a break here, otherwise we'll always
iterate over all the entries.

>> + }
>> + }
>> + }
>> +
>> + mutex_unlock(&reset_list_mutex);
>> +
>> + if (!rstc)
>> + return optional ? NULL : ERR_PTR(-ENOENT);
>> +
>> + return rstc;
>> +}
>> +
>> struct reset_control *__reset_control_get(struct device *dev, const char
>> *id,
>> int index, bool shared, bool
>> optional)
>> {
>> if (dev->of_node)
>> - return __of_reset_control_get(dev->of_node, id, index,
>> shared,
>> - optional);
>> + return __of_reset_control_get(dev->of_node, id,
>> + index, shared, optional);
>
>
> I don't understand why this line is changed. It is just being rearranged?
>

Yes, but I can leave it out of this patch.

>
>> + else
>> + return __reset_control_get_lookup(dev, id, shared,
>> optional);
>> return optional ? NULL : ERR_PTR(-EINVAL);
>> }
>> diff --git a/include/linux/reset-controller.h
>> b/include/linux/reset-controller.h
>> index adb88f8cefbc..0c081336e08b 100644
>> --- a/include/linux/reset-controller.h
>> +++ b/include/linux/reset-controller.h
>> @@ -22,6 +22,17 @@ struct reset_control_ops {
>> int (*status)(struct reset_controller_dev *rcdev, unsigned long
>> id);
>> };
>> +/**
>> + * struct reset_lookup - a single entry in a reset lookup table
>> + *
>> + * @dev: name of the device associated with this reset
>> + * @id: additional reset identifier (if the device uses multiple reset
>> lines)
>> + */
>> +struct reset_lookup {
>> + const char *dev;
>> + const char *id;
>> +};
>> +
>> struct module;
>> struct device_node;
>> struct of_phandle_args;
>> @@ -34,6 +45,7 @@ struct of_phandle_args;
>> * @list: internal list of reset controller devices
>> * @reset_control_head: head of internal list of requested reset
>> controls
>> * @of_node: corresponding device tree node as phandle target
>> + * @lookup: array of lookup entries associated with this request
>> controller
>
>
> Might be nice to mention that this array must end with an empty struct (i.e.
> lookup->dev == NULL)
>
>
>> * @of_reset_n_cells: number of cells in reset line specifiers
>> * @of_xlate: translation function to translate from specifier as found
>> in the
>> * device tree to id as given to the reset control ops
>> @@ -45,6 +57,7 @@ struct reset_controller_dev {
>> struct list_head list;
>> struct list_head reset_control_head;
>> struct device_node *of_node;
>> + const struct reset_lookup *lookup;
>> int of_reset_n_cells;
>> int (*of_xlate)(struct reset_controller_dev *rcdev,
>> const struct of_phandle_args *reset_spec);
>>
>

Bartosz

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