ARM: hw_breakpoint: add initial Cortex-A15 (debug v7.1) support

This patch adds initial support for Cortex-A15 (debug architecture v7.1)
to the hw_breakpoint ARM backend.

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

2 files changed, 37 insertions, 19 deletions

diff --git a/arch/arm/include/asm/hw_breakpoint.h b/arch/arm/include/asm/hw_breakpoint.h
index f389b2704d82..0ac141a87616 100644
--- a/arch/arm/include/asm/hw_breakpoint.h
+++ b/arch/arm/include/asm/hw_breakpoint.h
@@ -50,6 +50,7 @@ static inline void decode_ctrl_reg(u32 reg,
 #define ARM_DEBUG_ARCH_V6_1     2
 #define ARM_DEBUG_ARCH_V7_ECP14 3
 #define ARM_DEBUG_ARCH_V7_MM    4
+#define ARM_DEBUG_ARCH_V7_1     5
 
 /* Breakpoint */
 #define ARM_BREAKPOINT_EXECUTE  0
diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index a927ca1f5566..b6ddbfaae52c 100644
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -154,7 +154,10 @@ u8 arch_get_debug_arch(void)
 static int debug_arch_supported(void)
 {
         u8 arch = get_debug_arch();
-        return arch >= ARM_DEBUG_ARCH_V6 && arch <= ARM_DEBUG_ARCH_V7_ECP14;
+
+        /* We don't support the memory-mapped interface. */
+        return (arch >= ARM_DEBUG_ARCH_V6 && arch <= ARM_DEBUG_ARCH_V7_ECP14) ||
+                arch >= ARM_DEBUG_ARCH_V7_1;
 }
 
 /* Determine number of BRP register available. */
@@ -255,6 +258,7 @@ static int enable_monitor_mode(void)
                 ARM_DBG_WRITE(c1, 0, (dscr | ARM_DSCR_MDBGEN));
                 break;
         case ARM_DEBUG_ARCH_V7_ECP14:
+        case ARM_DEBUG_ARCH_V7_1:
                 ARM_DBG_WRITE(c2, 2, (dscr | ARM_DSCR_MDBGEN));
                 break;
         default:
@@ -836,7 +840,7 @@ static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr,
  */
 static void reset_ctrl_regs(void *info)
 {
-        int i, cpu = smp_processor_id();
+        int i, err = 0, cpu = smp_processor_id();
         u32 dbg_power;
         cpumask_t *cpumask = info;
 
@@ -848,33 +852,46 @@ static void reset_ctrl_regs(void *info)
          * Access Register to avoid taking undefined instruction exceptions
          * later on.
          */
-        if (debug_arch >= ARM_DEBUG_ARCH_V7_ECP14) {
+        switch (debug_arch) {
+        case 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;
-                }
-
+                if ((dbg_power & 0x1) == 0)
+                        err = -EPERM;
+                break;
+        case ARM_DEBUG_ARCH_V7_1:
                 /*
-                 * Unconditionally clear the lock by writing a value
-                 * other than 0xC5ACCE55 to the access register.
+                 * Ensure the OS double lock is clear.
                  */
-                asm volatile("mcr p14, 0, %0, c1, c0, 4" : : "r" (0));
-                isb();
+                asm volatile("mrc p14, 0, %0, c1, c3, 4" : "=r" (dbg_power));
+                if ((dbg_power & 0x1) == 1)
+                        err = -EPERM;
+                break;
+        }
 
-                /*
-                 * Clear any configured vector-catch events before
-                 * enabling monitor mode.
-                 */
-                asm volatile("mcr p14, 0, %0, c0, c7, 0" : : "r" (0));
-                isb();
+        if (err) {
+                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
+         * other than 0xC5ACCE55 to the access register.
+         */
+        asm volatile("mcr p14, 0, %0, c1, c0, 4" : : "r" (0));
+        isb();
+
+        /*
+         * Clear any configured vector-catch events before
+         * enabling monitor mode.
+         */
+        asm volatile("mcr p14, 0, %0, c0, c7, 0" : : "r" (0));
+        isb();
+
         if (enable_monitor_mode())
                 return;