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: 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: backend: Add more fields to struct state_backend_storage ...

To save a few function arguments.

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

state: bucket: Make output more informative ...

Print offset and number of the bucket along with the bucket
specific messages to give a hint which bucket a message is for.

Also it's pretty much expected that buckets sometimes have no
data or need cleanup, so instead of complaining loudly, only
write which bucket is used and which buckets are cleaned up.

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

state: Drop cache bucket ...

The cache bucket sits between the storage functions and the backend
storage. We only read from the storage once, so there is no need to cache
anything. The real purpose of the cache bucket is to keep the -EUCLEAN
information when a NAND block needs to be rewritten and to keep the read
buffers as long as the backend iterates over all buckets trying to find
the one we want to use.

This can be coded easier and more obvious in the backend code, so drop
the cache bucket.

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: replace len_hint logic ...

The len_hint mechanism is rather hard to understand as it's not clear
from where to where the hint is passed and also it's not clear what
happens if the hint is empty or wrong.

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

state: drop lazy_init ...

lazy_init is an optimization that makes it possible to read only up to
the first valid bucket when starting. However, when restoring consistency,
immediately afterwards we have we have to initialize all buckets anyway,
so being lazy doesn't give us any gain. Remove it to simplify the code.

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: 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: backend: remove len_hint argument from state_storage_read ...

The argument is 0 in the only caller, so remove the argument.

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

state: backend: remove .get_packed_len ...

.get_packed_len isn't implemented by any backend, so remove the
hook and its potential caller.

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

state: make locally used function static ...

state_set_dirty() is only used in one file, make it static.

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

state: Add state to state_variable ...

A state variable should know which state it belongs to. Add field
for it to struct state_variable.

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: copy backend of_path string ...

Caching pointers to device tree nodes or names is not safe. The barebox
internal device tree may be changed by loading a new device tree or through
fixup handlers. As a result, the string may be deleted.
Use local copies of the full path instead.

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>