[POWERPC] 4xx: Improve support for 4xx indirect DCRs

Accessing indirect DCRs is done via a pair of address/data DCRs.

Such accesses are thus inherently racy, vs. interrupts, preemption
and possibly SMP if 4xx SMP cores are ever used.

This updates the mfdcri/mtdcri macros in dcr-native.h (which were
so far unused) to use a spinlock.

In addition, add some common definitions to a new dcr-regs.h file.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>

1 files changed, 20 insertions, 10 deletions

diff --git a/include/asm-powerpc/dcr-native.h b/include/asm-powerpc/dcr-native.h
index 8dbb1ab0aa04..af5fb31af559 100644
--- a/include/asm-powerpc/dcr-native.h
+++ b/include/asm-powerpc/dcr-native.h
@@ -22,6 +22,8 @@
 #ifdef __KERNEL__
 #ifndef __ASSEMBLY__
 
+#include <linux/spinlock.h>
+
 typedef struct {
         unsigned int base;
 } dcr_host_t;
@@ -55,20 +57,28 @@ do {								\
 } while (0)
 
 /* R/W of indirect DCRs make use of standard naming conventions for DCRs */
-#define mfdcri(base, reg)                       \
-({                                              \
-        mtdcr(base ## _CFGADDR, base ## _ ## reg);      \
-        mfdcr(base ## _CFGDATA);                        \
+extern spinlock_t dcr_ind_lock;
+
+#define mfdcri(base, reg)                               \
+({                                                      \
+        unsigned long flags;                            \
+        unsigned int val;                               \
+        spin_lock_irqsave(&dcr_ind_lock, flags);        \
+        mtdcr(DCRN_ ## base ## _CONFIG_ADDR, reg);      \
+        val = mfdcr(DCRN_ ## base ## _CONFIG_DATA);     \
+        spin_unlock_irqrestore(&dcr_ind_lock, flags);   \
+        val;                                            \
 })
 
-#define mtdcri(base, reg, data)                 \
-do {                                            \
-        mtdcr(base ## _CFGADDR, base ## _ ## reg);      \
-        mtdcr(base ## _CFGDATA, data);          \
+#define mtdcri(base, reg, data)                         \
+do {                                                    \
+        unsigned long flags;                            \
+        spin_lock_irqsave(&dcr_ind_lock, flags);        \
+        mtdcr(DCRN_ ## base ## _CONFIG_ADDR, reg);      \
+        mtdcr(DCRN_ ## base ## _CONFIG_DATA, data);     \
+        spin_unlock_irqrestore(&dcr_ind_lock, flags);   \
 } while (0)
 
 #endif /* __ASSEMBLY__ */
 #endif /* __KERNEL__ */
 #endif /* _ASM_POWERPC_DCR_NATIVE_H */
-
-