Fix armv7r

Signal sent from work_signal() may interrupt the low priority worker thread that is already running. For example, the worker thread that is waiting for a semaphore could be woken up by the signal and break any synchronization assumption as a result. It also does not make any sense to send signal if it is already running and busy. This commit fixes it.

Thumb flag in CPSR is not restored back when the context switch occurs
while executing thumb instruction.

Reported-by: Eunbong Song <eunb.song@samsung.com>
Signed-off-by: Byoungtae Cho <bt.cho@samsung.com>
Signed-off-by: Heesub Shin <heesub.shin@samsung.com>

A sporadic hang with consequent crash is observed when booting:

    arm_prefetchabort: Prefetch abort. PC: 04d34a00 IFAR: 04d34a00 IFSR: 00000008
    up_assert: Assertion failed at file:armv7-r/arm_prefetchabort.c line: 87 task: init
    up_dumpstate: Current sp: 004c3df0
    up_dumpstate: Interrupt stack:
    up_dumpstate:   base: 004c05fc
    up_dumpstate:   size: 00000800
    up_dumpstate: User stack:
    up_dumpstate:   base: 004c3f58
    up_dumpstate:   size: 00000fec
    up_dumpstate: User Stack
    up_stackdump: 004c3de0: 004a0d14 004c3df0 004c3f58 004a0d20 00000057 004c2c58 09000000 004a42a4
    up_stackdump: 004c3e00: 00000003 004c3e10 004a0f1c 004bbcef 33c44b00 004a0f28 04d34a00 00000008
    up_stackdump: 004c3e20: 00000008 004a01bc 004bfd38 00000001 00007fff 00000001 34134a00 d83e4c00
    up_stackdump: 004c3e40: 09000000 00000000 33c44b00 d83e4c00 0c3f4c00 00000000 00000000 00000003
    up_stackdump: 004c3e60: 004c3e70 004a1494 04d34a00 200b0253 004c3ed8 004a5298 004c3ed8 6d00006d
    up_stackdump: 004c3e80: 0000006d 004bc3f4 00000009 004a4f64 00000009 b9e0784f 333f3ed0 69d4227d
    up_stackdump: 004c3ea0: d81f09bd 0f867344 5a7e2c12 8acefd34 5d00dc1b 004bc432 004c3f08 004c0e08
    up_stackdump: 004c3ec0: 00000000 00000000 00000000 00000000 00000000 004a4210 004a5258 004a5300
    up_stackdump: 004c3ee0: 00000000 00000001 ffffffff 004c3f80 000002b0 004a4234 00000007 004c3f08
    up_stackdump: 004c3f00: 004a58b4 004bc432 004bc3f4 004c3f80 000002b0 0000029c 00000000 0000029c
    up_stackdump: 004c3f20: 00000000 004a5900 0000ff01 00000000 00000000 004a61f4 00000000 004a5fa4
    up_stackdump: 004c3f40: 00000000 004a5f6c 00000000 004a2668 00000000 00000000 b7509f04 004c3f64
    up_registerdump: R0: 00000001 00007fff 00000001 34134a00 d83e4c00 09000000 00000000 33c44b00
    up_registerdump: R8: d83e4c00 0c3f4c00 00000000 00000000 00000003 004c3e70 004a1494 04d34a00
    up_registerdump: CPSR: 200b0253

It seems to be caused by the corrupted or wrong CPSR restored on return
from exception. NuttX restores the context using code like this:

    msr spsr, r1

GCC translates this to:

    msr spsr_fc, r1

As a result, not all SPSR fields are updated on exception return. This
should be:

    msr spsr_fsxc, r1

On some evaluation boards, spsr_svc may have totally invalid value at
power-on-reset. As it is not initialized at boot, the code above may
result in the corruption of cpsr and thus unexpected behavior.

Reported-by: Eunbong Song <eunb.song@samsung.com>
Signed-off-by: Heesub Shin <heesub.shin@samsung.com>

s/ARMV7M/ARMV7R/g

Reported-by: Eunbong Song <eunb.song@samsung.com>
Signed-off-by: Heesub Shin <heesub.shin@samsung.com>

This commit adds functions for enabling and disabling d/i-caches which
were missing for ARMv7-R.

Signed-off-by: Heesub Shin <heesub.shin@samsung.com>

Unlike in ARMv7-A/M, Kconfig entries for data and instruction caches
are currently missing in ARMv7-R. This commit adds those missing Kconfig
entries. Actual implmenetation for those functions will be added in the
subsequent patches.

Signed-off-by: Heesub Shin <heesub.shin@samsung.com>

mpu_control() is invoking cp15_wrsctlr() around SCTLR update
redundantly.

Signed-off-by: Heesub Shin <heesub.shin@samsung.com>

In ARMv7-R, [31:5] bits of DRBAR is physical base address and other bits
are reserved and SBZ. Thus, there is no point in passing other than the
base address.

Signed-off-by: Heesub Shin <heesub.shin@samsung.com>

This commit fixes compilation errors on MPU support for ARMv7-R.

Signed-off-by: Heesub Shin <heesub.shin@samsung.com>

fix trivial typo: s/ARMv7-A/ARMv7-R/

Signed-off-by: Heesub Shin <heesub.shin@samsung.com>

Update TODO.  Provide do-nothing stubs for mutex attribute interfaces if features not enabled.  pthread_cond includes a signaling semaphore and should call sem_setprotocol.

configs/misco:  CONFIG_DEFAULT_SMALL should not be set either. It is really too late now, hoever, because all of the small defaults have already been set.