state: remove unused variable type ...

enum state_variable_type is never used. Remove it.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

state: find device node from device path, not from device node path ...

The device node path may change from the internal device tree to the
one Linux is started with, so using this path to fixup the tree is
not very robust. Instead, use of_find_node_by_devpath() which has
been created for exactly this purpose.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

state: Do not load state during state_new_from_node ...

The caller of state_new_from_node() may have it's own ideas what to
do when loading the state fails, so do not load it in the initialization
function, but instead let the caller do it.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

state: Allow to load without authentification ...

Sometimes it's useful to be able to load a state even when it
can't be authentificated. Add an option for this.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

state: Convert all bufs to void * ...

A void * is a much better type for a buffer than a u8 * as it
can be casted to any other type implicitly. Convert all buffers
used by the state framework to void *.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

state: pass struct state * to storage functions ...

We can get a state_backend_storage * and the device * from struct state,
so pass this to the storage functions rather than the two pointers.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

state: remove unnecessary argument from state_format_init ...

The device pointer is already in struct state, no need to pass it
around when a struct state * is already passed.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

state: open code state_backend_init in caller ...

Safes a lot of argument passing to a function that is used
only once.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

state: merge backend.c into state.c ...

The code in backend.c is too small to justify an extra file. Merge it
into state.c.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

state: Drop backend as extra struct type ...

struct state_backend is embedded into struct state. This additional
indirection does not have any real gain. Drop it.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

state: Make pointing to the backend using a phandle the only supported method ...

All other methods are broken for some time already: When starting the
kernel the state code rewrites the state node in the device tree and
replaced the "backend" property with a phandle - even when the target
can't be described as a phandle. Since using phandles is the nicest way
to point to the storage device anyway remove the other methods.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

treewide: Use of_property_write_string() where appropriate ...

Replace users which use of_set_property() to set a property to a string
with of_property_write_string().

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

state: Use dev_* for information rather than pr_* ...

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

state: pass error code instead of inventing new one ...

Both of_find_path() and of_find_path_by_node() return a meaningful
error code, so forward it instead of inventing a new one. Do this
especially for the -EPROBE_DEFER case which currently does not work.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

state: fix finding the correct parent node ...

Looking for the parent node during fixup is broken. The path of the parent
node is not correctly terminated ('0' vs '\0'). Also, the new state node
should be added to the supplied device tree not the barebox device tree
used by of_find_node_by_path().

Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

state: don't keep pointers to device tree nodes ...

Caching pointers to device tree nodes or is not save. The barebox internal
device tree may be changed by loading a new device tree or through fixup
handlers. As a result, the node may be deleted and replaced with a new one.
Keep a copy of the full path instead and resolve the node as needed.

Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

state: Save on shutdown ...

The state framework is meant for storing persistent variables. To
make the state more persistent automatically save it on shutdown.
This is now the default behaviour, but can be disabled using a
'save_on_shutdown' variable attached to the state.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

state: also append backend storage stridesize ...

Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

state: Refactor state framework ...

The state framework grew organically over the time. Unfortunately the
architecture and abstractions disappeared during this period.

This patch refactors the framework to recreate the abstractions. The
main focus was the backend with its storage. The main use-case was to
offer better NAND support with less erase cycles and interchangeable
data formats (dtb,raw).

The general architecture now has a backend which consists of a data
format and storage. The storage consists of multiple storage buckets
each holding exactly one copy of the state data. A data format describes
a data serialization for the state framework. This can be either dtb or
raw. A storage bucket is a storage location which is used to store any
data. There is a (new) circular type which writes changes behind the
last written data and therefore reduces the number of erases. The other
type is a direct bucket which writes directly to a storage offset for
all non-erase storage.

Furthermore this patch splits up all classes into different files in a
subdirectory.

This is currently all in one patch as I can't see a good way to split
the changes up without having a non-working state framework in between.

The following diagram shows the new architecture roughly:

           .----------.
           |  state   |
           '----------'
                 |
                 |
                 v
  .----------------------------.
  |       state_backend        |
  |----------------------------|
  | + state_load(*state);      |
  | + state_save(*state);      |
  | + state_backend_init(...); |
  |                            |
  |                            |
  '----------------------------'
    |            |                   The format describes
    |            |                   how the state data
    |            '------------->     is serialized
    |   .--------------------------------------------.
    |   |      state_backend_format <INTERFACE>      |
    |   |--------------------------------------------|
    |   | + verify(*format, magic, *buf, len);       |
    |   | + pack(*format, *state, **buf, len);       |
    |   | + unpack(*format, *state, *buf, len);      |
    |   | + get_packed_len(*format, *state);         |
    |   | + free(*format);                           |
    |   '--------------------------------------------'
    |              ^                      ^
    |              *                      *
    |              *                      *
    |   .--------------------. .--------------------.
    |   | backend_format_dtb | | backend_format_raw |
    |   '--------------------' '--------------------'
    |
    |
    |
    v
.----------------------------------------------------------.
|                  state_backend_storage                   |
|----------------------------------------------------------|
| + init(...);                                             |
| + free(*storage);                                        |
| + read(*storage, *format, magic, **buf, *len, len_hint); |
| + write(*storage, *buf, len);                            |
| + restore_consistency(*storage, *buf, len);              |
'----------------------------------------------------------'
                              |
     The backend storage is responsible to manage multiple
     data copies and distribute them onto several buckets.
     Read data is verified against the given format to
     ensure that the read data is correct.
                              |
                              |
                              |
                              |
                              |
                              v
        .------------------------------------------.
        | state_backend_storage_bucket <INTERFACE> |
        |------------------------------------------|
        | + init(*bucket);                         |
        | + write(*bucket, *buf, len);             |
        | + read(*bucket, **buf, len_hint);        |
        | + free(*bucket);                         |
        '------------------------------------------'
                      ^     ^      ^
                     *      *       *
                    *       *        *
 A storage bucket represents*exactly one data copy at one
 data location. A circular b*cket writes any new data to
 the end of the bucket (for *educed erases on NAND). A
 direct bucket directly writ*s at one location.
               *            *             *
              *             *              *
             *              *               *
 .-----------------------.  *  .-------------------------.
 | backend_bucket_direct |  *  | backend_bucket_circular |
 '-----------------------'  *  '-------------------------'
             ^              *               ^
             |              *               |
             |              *               |
             |              *               |
             |  .-----------------------.   |
             '--| backend_bucket_cached |---'
                '-----------------------'
             A backend_bucket_cached is a transparent
             bucket that directly uses another bucket
             as backend device and caches all accesses.

Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>