We must not declare dbg_cpu_pm_nb as __cpuinitdata as we need it after
system initialization for Suspend and CPUIdle.

This was done in commit 9a6eb310eaa5 ("ARM: hw_breakpoint: Debug powerdown
support for self-hosted debug").

Cc: stable@vger.kernel.org
Cc: Dietmar Eggemann <Dietmar.Eggemann@arm.com>
Signed-off-by: Bastian Hecht <hechtb+renesas@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

CPU debug features like hardware break, watchpoints can be used only
when the debug mode is enabled and available. Unfortunately on OMAP4
based devices, after a CPU power cycle, the debug feature gets disabled
which leads to a flood of messages coming from reset_ctrl_regs() which
gets called on every CPU_PM_EXIT with CPUidle enabled.

So make use of warn_once() so that system is usable.

Thanks to Will for pointers and Lokesh for the analysis of the issue.

Tested-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

We must mask out the CPU_TASKS_FROZEN bit so that reset_ctrl_regs is
also called on a secondary CPU during s2ram resume, where only the boot
CPU will receive the PM_EXIT notification.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

This patch introduces debug powerdown support for self-hosted debug for v7
and v7.1 debug architecture for a SinglePower system, i.e. a system without a
separate core and debug power domain. On a SinglePower system the OS Lock is
lost over a powerdown.

If CONFIG_CPU_PM is set the new function pm_init() registers hw_breakpoint
with CPU PM for a system supporting OS Save and Restore.

Receiving a CPU PM EXIT notifier indicates that a single CPU has exited a low
power state. A call to reset_ctrl_regs() is hooked into the CPU PM EXIT
notifier chain. This function makes sure that the sticky power-down is clear
(only v7 debug), the OS Double Lock is clear (only v7.1 debug) and it clears
the OS Lock for v7 debug (for a system supporting OS Save and Restore) and
v7.1 debug. Furthermore, it clears any vector-catch events and all
breakpoint/watchpoint control/value registers for v7 and v7.1 debug.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
[will: removed redundant has_ossr check]
Signed-off-by: Will Deacon <will.deacon@arm.com>

v7 debug introduced OS Save and Restore mechanism. On a v7 debug SinglePower
system, i.e a system without a separate core and debug power domain, which does
not support external debug over powerdown, it is implementation defined whether
OS Save and Restore is implemented.
v7.1 debug requires OS Save and Restore mechanism. v6 debug and v6.1 debug do
not implement it.

A new global variable bool has_ossr is introduced and is determined in
arch_hw_breakpoint_init() like debug_arch or the number of BRPs/WRPs.

The logic how to check if OS Save and Restore is supported has changed with
this patch. In reset_ctrl_regs() a mask consisting of OSLM[1] (OSLSR.3) and
OSLM[0] (OSLSR.0) was used to check if the system supports OS Save and
Restore. In the new function core_has_os_save_restore() only OSLM[0] is used.
It is not necessary to check OSLM[1] too since it is v7.1 debug specific and
v7.1 debug requires OS Save and Restore and thus OS Lock.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

Coresight components and debug are using a common lock control mechansim.
Writing 0xC5ACCE55 to the Lock Access Register (LAR) in case of a coresight
components enables further access to the coresight device registers. Writing
any other value to it removes the write access.
Writing 0xC5ACCE55 to the OS Lock Access Register (OSLAR) in case of debug
locks the debug register for further access to the debug registers. Writing
any other value to it unlocks the debug registers.

Unfortunately, the existing coresight code uses the terms lock and unlock the
other way around. Unlocking stands for enabling write access and locking for
removing write access.

That is why the definition of the LAR and OSLAR key value has been changed to
CS_LAR_KEY.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

WARN_ONCE is a bit OTT for some of the simple failure cases encountered
in hw_breakpoint, so use either pr_warning or pr_warn_once instead.

Reported-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

The coprocessor register CRn for accesses to the debug register can be a
different one than C0. Take this into account for the ARM_DBG_READ and
the ARM_DBG_WRITE macro.

The inline assembler calls which used a coprocessor register CRn other
than C0 are replaced by the ARM_DBG_READ or ARM_DBG_WRITE macro.

Tested-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

Rather than attempt to enable monitor mode explicitly when scheduling in
a breakpoint event (which could raise an undefined exception trap when
accessing DBGDSCRext), instead check that DBGDSCRint.MDBGen is set
during event validation and report an error to the caller if not.

Signed-off-by: Will Deacon <will.deacon@arm.com>

Booting on a v6 core without the CPUID feature registers (e.g. 1136)
leads to a noisy dmesg complaining about their absence.

This patch changes the pr_warning into a pr_warn_once to keep the log
quieter.

Signed-off-by: Will Deacon <will.deacon@arm.com>