[PATCH 1/3] ARM: coresight: common definition for (OS) Lock Access Register key value

[Will Deacon]

From: Dietmar Eggemann <dietmar.eggemann at 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 at arm.com>
Signed-off-by: Will Deacon <will.deacon at arm.com>
---
 arch/arm/include/asm/cti.h                | 10 +++-------
 arch/arm/include/asm/hardware/coresight.h |  6 +++---
 arch/arm/kernel/hw_breakpoint.c           |  5 +++--
 3 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/arch/arm/include/asm/cti.h b/arch/arm/include/asm/cti.h
index f2e5cad..2381199 100644
--- a/arch/arm/include/asm/cti.h
+++ b/arch/arm/include/asm/cti.h
@@ -2,6 +2,7 @@
 #define __ASMARM_CTI_H
 
 #include	<asm/io.h>
+#include	<asm/hardware/coresight.h>
 
 /* The registers' definition is from section 3.2 of
  * Embedded Cross Trigger Revision: r0p0
@@ -35,11 +36,6 @@
 #define		LOCKACCESS		0xFB0
 #define		LOCKSTATUS		0xFB4
 
-/* write this value to LOCKACCESS will unlock the module, and
- * other value will lock the module
- */
-#define		LOCKCODE		0xC5ACCE55
-
 /**
  * struct cti - cross trigger interface struct
  * @base: mapped virtual address for the cti base
@@ -146,7 +142,7 @@ static inline void cti_irq_ack(struct cti *cti)
  */
 static inline void cti_unlock(struct cti *cti)
 {
-	__raw_writel(LOCKCODE, cti->base + LOCKACCESS);
+	__raw_writel(CS_LAR_KEY, cti->base + LOCKACCESS);
 }
 
 /**
@@ -158,6 +154,6 @@ static inline void cti_unlock(struct cti *cti)
  */
 static inline void cti_lock(struct cti *cti)
 {
-	__raw_writel(~LOCKCODE, cti->base + LOCKACCESS);
+	__raw_writel(~CS_LAR_KEY, cti->base + LOCKACCESS);
 }
 #endif
diff --git a/arch/arm/include/asm/hardware/coresight.h b/arch/arm/include/asm/hardware/coresight.h
index 7ecd793..0cf7a6b 100644
--- a/arch/arm/include/asm/hardware/coresight.h
+++ b/arch/arm/include/asm/hardware/coresight.h
@@ -36,7 +36,7 @@
 /* CoreSight Component Registers */
 #define CSCR_CLASS	0xff4
 
-#define UNLOCK_MAGIC	0xc5acce55
+#define CS_LAR_KEY	0xc5acce55
 
 /* ETM control register, "ETM Architecture", 3.3.1 */
 #define ETMR_CTRL		0
@@ -147,11 +147,11 @@
 
 #define etm_lock(t) do { etm_writel((t), 0, CSMR_LOCKACCESS); } while (0)
 #define etm_unlock(t) \
-	do { etm_writel((t), UNLOCK_MAGIC, CSMR_LOCKACCESS); } while (0)
+	do { etm_writel((t), CS_LAR_KEY, CSMR_LOCKACCESS); } while (0)
 
 #define etb_lock(t) do { etb_writel((t), 0, CSMR_LOCKACCESS); } while (0)
 #define etb_unlock(t) \
-	do { etb_writel((t), UNLOCK_MAGIC, CSMR_LOCKACCESS); } while (0)
+	do { etb_writel((t), CS_LAR_KEY, CSMR_LOCKACCESS); } while (0)
 
 #endif /* __ASM_HARDWARE_CORESIGHT_H */
 
diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index 5ff2e77..34e9375 100644
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -35,6 +35,7 @@
 #include <asm/hw_breakpoint.h>
 #include <asm/kdebug.h>
 #include <asm/traps.h>
+#include <asm/hardware/coresight.h>
 
 /* Breakpoint currently in use for each BRP. */
 static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[ARM_MAX_BRP]);
@@ -955,9 +956,9 @@ static void reset_ctrl_regs(void *unused)
 
 	/*
 	 * Unconditionally clear the OS lock by writing a value
-	 * other than 0xC5ACCE55 to the access register.
+	 * other than CS_LAR_KEY to the access register.
 	 */
-	ARM_DBG_WRITE(c1, c0, 4, 0);
+	ARM_DBG_WRITE(c1, c0, 4, ~CS_LAR_KEY);
 	isb();
 
 	/*
-- 
1.8.0