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ARM: 6768/1: hw_breakpoint: ensure debug logic is powered up on v7 cores

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ARMv7 allows the debug core logic to be powered down and provides the
DBGPRSR register so that software can power-up and check the status of
the logic.

This patch ensures that the debug logic is powered up on ARMv7 cores
before we attempt to access the extended debug registers.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Will Deacon 2011-02-25 20:20:42 +01:00 committed by Russell King
parent ba55d3db9b
commit c09bae7091
1 changed files with 23 additions and 3 deletions
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26
arch/arm/kernel/hw_breakpoint.c
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@ -836,9 +836,11 @@ static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr,
/* /*
* One-time initialisation. * One-time initialisation.
*/ */
static void reset_ctrl_regs(void *unused) static void reset_ctrl_regs(void *info)
{ {
int i; int i, cpu = smp_processor_id();
u32 dbg_power;
cpumask_t *cpumask = info;
/* /*
* v7 debug contains save and restore registers so that debug state * v7 debug contains save and restore registers so that debug state
@ -849,6 +851,17 @@ static void reset_ctrl_regs(void *unused)
* later on. * later on.
*/ */
if (debug_arch >= ARM_DEBUG_ARCH_V7_ECP14) { if (debug_arch >= ARM_DEBUG_ARCH_V7_ECP14) {
/*
* Ensure sticky power-down is clear (i.e. debug logic is
* powered up).
*/
asm volatile("mrc p14, 0, %0, c1, c5, 4" : "=r" (dbg_power));
if ((dbg_power & 0x1) == 0) {
pr_warning("CPU %d debug is powered down!\n", cpu);
cpumask_or(cpumask, cpumask, cpumask_of(cpu));
return;
}
/* /*
* Unconditionally clear the lock by writing a value * Unconditionally clear the lock by writing a value
* other than 0xC5ACCE55 to the access register. * other than 0xC5ACCE55 to the access register.
@ -887,6 +900,7 @@ static struct notifier_block __cpuinitdata dbg_reset_nb = {
static int __init arch_hw_breakpoint_init(void) static int __init arch_hw_breakpoint_init(void)
{ {
u32 dscr; u32 dscr;
cpumask_t cpumask = { CPU_BITS_NONE };
debug_arch = get_debug_arch(); debug_arch = get_debug_arch();
@ -911,7 +925,13 @@ static int __init arch_hw_breakpoint_init(void)
* Reset the breakpoint resources. We assume that a halting * Reset the breakpoint resources. We assume that a halting
* debugger will leave the world in a nice state for us. * debugger will leave the world in a nice state for us.
*/ */
on_each_cpu(reset_ctrl_regs, NULL, 1); on_each_cpu(reset_ctrl_regs, &cpumask, 1);
if (!cpumask_empty(&cpumask)) {
core_num_brps = 0;
core_num_reserved_brps = 0;
core_num_wrps = 0;
return 0;
}
ARM_DBG_READ(c1, 0, dscr); ARM_DBG_READ(c1, 0, dscr);
if (dscr & ARM_DSCR_HDBGEN) { if (dscr & ARM_DSCR_HDBGEN) {