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This patch saves the 'power_state' parameter prior to suspending
a cpu and invalidates it upon its resumption. The 'affinity level'
and 'state id' fields of this parameter can be read using a set of
public and private apis. Validation of power state parameter is
introduced which checks for SBZ bits are zero.
This change also takes care of flushing the parameter from the cache
to main memory. This ensures that it is available after cpu reset
when the caches and mmu are turned off. The earlier support for
saving only the 'affinity level' field of the 'power_state' parameter
has also been reworked.

Fixes ARM-Software/tf-issues#26
Fixes ARM-Software/tf-issues#130

Change-Id: Ic007ccb5e39bf01e0b67390565d3b4be33f5960a

This patch implements ARM Standard Service as a runtime service and adds
support for call count, UID and revision information SMCs. The existing
PSCI implementation is subsumed by the Standard Service calls and all
PSCI calls are therefore dispatched by the Standard Service to the PSCI
handler.

At present, PSCI is the only specification under Standard Service. Thus
call count returns the number of PSCI calls implemented. As this is the
initial implementation, a revision number of 0.1 is returned for call
revision.

Fixes ARM-software/tf-issues#62

Change-Id: I6d4273f72ad6502636efa0f872e288b191a64bc1

This patch creates a 'services' directory and moves the PSCI under
it. Other runtime services e.g. the Secure Payload Dispatcher service
will be placed under the same directory in the future.

Also fixes issue ARM-software/tf-issues#12

Change-Id: I187f83dcb660b728f82155d91882e961d2255068

This patch uses the reworked exception handling support to handle
runtime service requests through SMCs following the SMC calling
convention. This is a giant commit since all the changes are
inter-related. It does the following:

1. Replace the old exception handling mechanism with the new one
2. Enforce that SP_EL0 is used C runtime stacks.
3. Ensures that the cold and warm boot paths use the 'cpu_context'
   structure to program an ERET into the next lower EL.
4. Ensures that SP_EL3 always points to the next 'cpu_context'
   structure prior to an ERET into the next lower EL
5. Introduces a PSCI SMC handler which completes the use of PSCI as a
   runtime service

Change-Id: I661797f834c0803d2c674d20f504df1b04c2b852
Co-authored-by: Achin Gupta <achin.gupta@arm.com>

This patch introduces the framework to enable registration and
initialisation of runtime services. PSCI is registered and initialised
as a runtime service. Handling of runtime service requests will be
implemented in subsequent patches.

Change-Id: Id21e7ddc5a33d42b7d6e455b41155fc5441a9547

This patch uses the context library to save and restore EL3 state on
the 'cpu_context' data structures allocated by PSCI for managing
non-secure state context on each cpu.

Change-Id: I19c1f26578204a7cd9e0a6c582ced0d97ee4cf80

Also fix warnings generated in release builds when assert code
is absent.

Change-Id: I45b9173d3888f9e93e98eb5b4fdc06727ba5cbf4

The psci implementation does not track target affinity level requests
specified during cpu_suspend calls correctly as per the following
example.

1. cpu0.cluster0 calls cpu_suspend with the target affinity level as 0
2. Only the cpu0.cluster0 is powered down while cluster0 remains
   powered up
3. cpu1.cluster0 calls cpu_off to power itself down to highest
   possible affinity level
4. cluster0 will be powered off even though cpu0.cluster0 does not
   allow cluster shutdown

This patch introduces reference counts at affinity levels > 0 to track
the number of cpus which want an affinity instance at level X to
remain powered up. This instance can be turned off only if its
reference count is 0. Cpus still undergo the normal state transitions
(ON, OFF, ON_PENDING, SUSPEND) but the higher levels can only be
either ON or OFF depending upon their reference count.

The above issue is thus fixed as follows:

1. cluster0's reference count is incremented by two when cpu0 and cpu1
   are initially powered on.

2. cpu0.cluster0 calls cpu_suspend with the target affinity level as
   0. This does not affect the cluster0 reference count.

3. Only the cpu0.cluster0 is powered down while cluster0 remains
   powered up as it has a non-zero reference count.

4. cpu1.cluster0 call cpu_off to power itself down to highest possible
   affinity level. This decrements the cluster0 reference count.

5. cluster0 is still not powered off since its reference count will at
   least be 1 due to the restriction placed by cpu0.

Change-Id: I433dfe82b946f5f6985b1602c2de87800504f7a9

Change-Id: Ic7fb61aabae1d515b9e6baf3dd003807ff42da60

This patch performs a major rework of the psci generic implementation
to achieve the following:

1. replace recursion with iteration where possible to aid code
   readability e.g. affinity instance states are changed iteratively
   instead of recursively.

2. acquire pointers to affinity instance nodes at the beginning of a
   psci operation. All subsequent actions use these pointers instead
   of calling psci_get_aff_map_node() repeatedly e.g. management of
   locks has been abstracted under functions which use these pointers
   to ensure correct ordering. Helper functions have been added to
   create these abstractions.

3. assertions have been added to cpu level handlers to ensure correct
   state transition

4. the affinity level extents specified to various functions have the
   same meaning i.e. start level is always less than the end level.

Change-Id: If0508c3a7b20ea3ddda2a66128429382afc3dfc8

- Add instructions for contributing to ARM Trusted Firmware.

- Update copyright text in all files to acknowledge contributors.

Change-Id: I9311aac81b00c6c167d2f8c889aea403b84450e5