The dma_cache_wback_inv function performs exactly as is required here,
unless the system has coherent I/O in which case it's a no-op. Call the
underlying cache writeback functions directly, which is arguably clearer
anyway given that the code doesn't actually have anything to do with
DMA in a strict sense.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7282/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

When determining the VPE ID of a CPU, make use of the cpu_vpe_id macro
which will return 0 in a non-MT kernel build. Most code is already doing
so but a couple of places weren't. Fixing this prevents a build failure
for non-MT kernels where struct cpuinfo_mips does not contain the vpe_id
field:

  arch/mips/kernel/pm-cps.c: In function 'cps_pm_enter_state':
  arch/mips/kernel/pm-cps.c:153:51: error: 'struct cpuinfo_mips' has no
      member named 'vpe_id'
    vpe_cfg = &core_cfg->vpe_config[current_cpu_data.vpe_id];

  arch/mips/kernel/smp-cps.c: In function 'wait_for_sibling_halt':
  arch/mips/kernel/smp-cps.c:363:33: error: 'struct cpuinfo_mips' has no
      member named 'vpe_id'
    unsigned vpe_id = cpu_data[cpu].vpe_id;
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Reviewed-by: NMarkos Chandras <markos.chandras@imgtec.com>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Commit 91bbefe6 "arch,mips: Convert smp_mb__*()" replaced the
smp_mb__after_atomic_dec function with smp_mb__after_atomic, whilst
commit 1d8f1f5a "MIPS: smp-cps: hotplug support" introduced a new
use of it. Replace that use with smp_mb__after_atomic in order to avoid
a build failure:

  arch/mips/kernel/smp-cps.c: In function 'cps_cpu_disable':
  arch/mips/kernel/smp-cps.c:304:2: error: 'smp_mb__after_atomic_dec' is
    deprecated (declared at include/linux/atomic.h:35)
    [-Werror=deprecated-declarations]
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Reviewed-by: NMarkos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7085/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Rather than hardcoding CCA=0x5 for secondary cores, re-use the CCA from
the boot CPU. This allows overrides of the CCA using the cca= kernel
parameter to take effect on all CPUs for consistency.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>

This patch sets a default CCA suited for use with multi-core SMP on all
current MIPS CPS based systems. It may still be overriden by the cca=
argument on the kernel command line.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>

If the user or bootloader sets the CCA to a value which is not suited
for multi-core SMP (ie. anything non-coherent) then limit the system to
using only a single core and warn the user.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>

This patch adds support for offlining CPUs via hotplug when using the
CONFIG_MIPS_CPS SMP implementation. When a CPU is offlined one of 2
things will happen:

  - If the CPU is part of a core which implements the MT ASE and there
    is at least one other VPE online within that core then the VPE will
    be halted by settings its TCHalt bit.

  - Otherwise if supported the core will be powered down via the CPC.

  - Otherwise the CPU will hang by executing an infinite loop.

Bringing CPUs back online is then a process of either clearing the
appropriate VPEs TCHalt bit or powering up the appropriate core via the
CPC. Throughout the process the struct core_boot_config vpe_mask field
must be maintained such that mips_cps_boot_vpes will start & stop the
correct VPEs.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>

The core which the CPC core-other region relates to is based upon the
core-local core-other addressing register. As its name suggests this
register is shared between all VPEs within a core, and if there is a
possibility that multiple VPEs within a core will attempt to access
another core simultaneously then locking is required. This wasn't
previously a problem with the only user being cpu0 during boot, but will
be an issue once hotplug is implemented & may race with other users such
as cpuidle.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>

The start of mips_cps_core_entry is patched in order to provide the code
with the address of the CM register region at a point where it will be
running non-coherent with the rest of the system. However the cache
wasn't being flushed after that patching which could in principle lead
to secondary cores using an invalid CM base address.

The patching is moved to cps_prepare_cpus since local_flush_icache_range
has not been initialised at the point cps_smp_setup is called.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>

The core power down state for cpuidle will require that the CPS SMP
implementation is in use. This patch provides a mips_cps_smp_in_use
function which determines whether or not the CPS SMP implementation is
currently in use.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>

When hotplug and/or a powered down idle state are supported cases will
arise where a non-zero VPE must be brought online without VPE 0, and it
where multiple VPEs must be onlined simultaneously. This patch prepares
for that by:

  - Splitting struct boot_config into core & VPE boot config structures,
    allocated one per core or VPE respectively. This allows for multiple
    VPEs to be onlined simultaneously without clobbering each others
    configuration.

  - Indicating which VPEs should be online within a core at any given
    time using a bitmap. This allows multiple VPEs to be brought online
    simultaneously and also indicates to VPE 0 whether it should halt
    after starting any non-zero VPEs that should be online within the
    core. For example if all VPEs within a core are offlined via hotplug
    and the user onlines the second VPE within that core:

      1) The core will be powered up.

      2) VPE 0 will run from the BEV (ie. mips_cps_core_entry) to
         initialise the core.

      3) VPE 0 will start VPE 1 because its bit is set in the cores
         bitmap.

      4) VPE 0 will halt itself because its bit is clear in the cores
         bitmap.

  - Moving the core & VPE initialisation to assembly code which does not
    make any use of the stack. This is because if a non-zero VPE is to
    be brought online in a powered down core then when VPE 0 of that
    core runs it may not have a valid stack, and even if it did then
    it's messy to run through parts of generic kernel code on VPE 0
    before starting the correct VPE.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>

Nothing was using the method and there isn't any need for this hook.  This
leaves smp_cpus_done() empty for the moment.

As suggested by Paul Bolle <pebolle@tiscali.nl>.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

This patch introduces a new SMP implementation for systems implementing
the MIPS Coherent Processing System architecture. The kernel will make
use of the Coherence Manager, Cluster Power Controller & Global
Interrupt Controller in order to detect, bring up & make use of other
cores in the system. SMTC is not supported, so only a single TC per VPE
in the system is used. That is, this option enables an SMVP style setup
but across multiple cores.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6362/
Patchwork: https://patchwork.linux-mips.org/patch/6611/
Patchwork: https://patchwork.linux-mips.org/patch/6651/
Patchwork: https://patchwork.linux-mips.org/patch/6652/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>