powerpc/4xx: Extended DCR support v2

This adds supports to the "extended" DCR addressing via the indirect
mfdcrx/mtdcrx instructions supported by some 4xx cores (440H6 and
later).

I enabled the feature for now only on AMCC 460 chips.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 51 insertions, 12 deletions

diff --git a/arch/powerpc/include/asm/dcr-native.h b/arch/powerpc/include/asm/dcr-native.h
index 72d2b72c739..7d2e6235726 100644
--- a/arch/powerpc/include/asm/dcr-native.h
+++ b/arch/powerpc/include/asm/dcr-native.h
@@ -23,6 +23,7 @@
 #ifndef __ASSEMBLY__
 
 #include <linux/spinlock.h>
+#include <asm/cputable.h>
 
 typedef struct {
         unsigned int base;
@@ -39,23 +40,45 @@ static inline bool dcr_map_ok_native(dcr_host_native_t host)
 #define dcr_read_native(host, dcr_n)            mfdcr(dcr_n + host.base)
 #define dcr_write_native(host, dcr_n, value)    mtdcr(dcr_n + host.base, value)
 
-/* Device Control Registers */
-void __mtdcr(int reg, unsigned int val);
-unsigned int __mfdcr(int reg);
+/* Table based DCR accessors */
+extern void __mtdcr(unsigned int reg, unsigned int val);
+extern unsigned int __mfdcr(unsigned int reg);
+
+/* mfdcrx/mtdcrx instruction based accessors. We hand code
+ * the opcodes in order not to depend on newer binutils
+ */
+static inline unsigned int mfdcrx(unsigned int reg)
+{
+        unsigned int ret;
+        asm volatile(".long 0x7c000206 | (%0 << 21) | (%1 << 16)"
+                     : "=r" (ret) : "r" (reg));
+        return ret;
+}
+
+static inline void mtdcrx(unsigned int reg, unsigned int val)
+{
+        asm volatile(".long 0x7c000306 | (%0 << 21) | (%1 << 16)"
+                     : : "r" (val), "r" (reg));
+}
+
 #define mfdcr(rn)                                               \
         ({unsigned int rval;                                    \
-        if (__builtin_constant_p(rn))                           \
+        if (__builtin_constant_p(rn) && rn < 1024)              \
                 asm volatile("mfdcr %0," __stringify(rn)        \
                               : "=r" (rval));                   \
+        else if (likely(cpu_has_feature(CPU_FTR_INDEXED_DCR)))  \
+                rval = mfdcrx(rn);                              \
         else                                                    \
                 rval = __mfdcr(rn);                             \
         rval;})
 
 #define mtdcr(rn, v)                                            \
 do {                                                            \
-        if (__builtin_constant_p(rn))                           \
+        if (__builtin_constant_p(rn) && rn < 1024)              \
                 asm volatile("mtdcr " __stringify(rn) ",%0"     \
                               : : "r" (v));                     \
+        else if (likely(cpu_has_feature(CPU_FTR_INDEXED_DCR)))  \
+                mtdcrx(rn, v);                                  \
         else                                                    \
                 __mtdcr(rn, v);                                 \
 } while (0)
@@ -69,8 +92,13 @@ static inline unsigned __mfdcri(int base_addr, int base_data, int reg)
         unsigned int val;
 
         spin_lock_irqsave(&dcr_ind_lock, flags);
-        __mtdcr(base_addr, reg);
-        val = __mfdcr(base_data);
+        if (cpu_has_feature(CPU_FTR_INDEXED_DCR)) {
+                mtdcrx(base_addr, reg);
+                val = mfdcrx(base_data);
+        } else {
+                __mtdcr(base_addr, reg);
+                val = __mfdcr(base_data);
+        }
         spin_unlock_irqrestore(&dcr_ind_lock, flags);
         return val;
 }
@@ -81,8 +109,13 @@ static inline void __mtdcri(int base_addr, int base_data, int reg,
         unsigned long flags;
 
         spin_lock_irqsave(&dcr_ind_lock, flags);
-        __mtdcr(base_addr, reg);
-        __mtdcr(base_data, val);
+        if (cpu_has_feature(CPU_FTR_INDEXED_DCR)) {
+                mtdcrx(base_addr, reg);
+                mtdcrx(base_data, val);
+        } else {
+                __mtdcr(base_addr, reg);
+                __mtdcr(base_data, val);
+        }
         spin_unlock_irqrestore(&dcr_ind_lock, flags);
 }
 
@@ -93,9 +126,15 @@ static inline void __dcri_clrset(int base_addr, int base_data, int reg,
         unsigned int val;
 
         spin_lock_irqsave(&dcr_ind_lock, flags);
-        __mtdcr(base_addr, reg);
-        val = (__mfdcr(base_data) & ~clr) | set;
-        __mtdcr(base_data, val);
+        if (cpu_has_feature(CPU_FTR_INDEXED_DCR)) {
+                mtdcrx(base_addr, reg);
+                val = (mfdcrx(base_data) & ~clr) | set;
+                mtdcrx(base_data, val);
+        } else {
+                __mtdcr(base_addr, reg);
+                val = (__mfdcr(base_data) & ~clr) | set;
+                __mtdcr(base_data, val);
+        }
         spin_unlock_irqrestore(&dcr_ind_lock, flags);
 }