MIPS: Netlogic: Add 32-bit support for XLP

Update asm/netlogic/haldefs.h to extend register access functions
nlm_{read,write}_reg64() for 32-bit compilation. When compiled for 32-bit
the functions will read 64 IO registers with interrupts disabled.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
Patchwork: http://patchwork.linux-mips.org/patch/5026/
Acked-by: John Crispin <blogic@openwrt.org>

1 files changed, 50 insertions, 6 deletions

diff --git a/arch/mips/include/asm/netlogic/haldefs.h b/arch/mips/include/asm/netlogic/haldefs.h
index 419d8aef8569..61fecb85e66f 100644
--- a/arch/mips/include/asm/netlogic/haldefs.h
+++ b/arch/mips/include/asm/netlogic/haldefs.h
@@ -35,14 +35,13 @@
 #ifndef __NLM_HAL_HALDEFS_H__
 #define __NLM_HAL_HALDEFS_H__
 
+#include <linux/irqflags.h>     /* for local_irq_disable */
+
 /*
  * This file contains platform specific memory mapped IO implementation
  * and will provide a way to read 32/64 bit memory mapped registers in
  * all ABIs
  */
-#if !defined(CONFIG_64BIT) && defined(CONFIG_CPU_XLP)
-#error "o32 compile not supported on XLP yet"
-#endif
 /*
  * For o32 compilation, we have to disable interrupts and enable KX bit to
  * access 64 bit addresses or data.
@@ -87,13 +86,40 @@ nlm_write_reg(uint64_t base, uint32_t reg, uint32_t val)
         *addr = val;
 }
 
+/*
+ * For o32 compilation, we have to disable interrupts to access 64 bit
+ * registers
+ *
+ * We need to disable interrupts because we save just the lower 32 bits of
+ * registers in  interrupt handling. So if we get hit by an interrupt while
+ * using the upper 32 bits of a register, we lose.
+ */
+
 static inline uint64_t
 nlm_read_reg64(uint64_t base, uint32_t reg)
 {
         uint64_t addr = base + (reg >> 1) * sizeof(uint64_t);
         volatile uint64_t *ptr = (volatile uint64_t *)(long)addr;
-
-        return *ptr;
+        uint64_t val;
+
+        if (sizeof(unsigned long) == 4) {
+                unsigned long flags;
+
+                local_irq_save(flags);
+                __asm__ __volatile__(
+                        ".set   push"                   "\n\t"
+                        ".set   mips64"                 "\n\t"
+                        "ld     %L0, %1"                "\n\t"
+                        "dsra32 %M0, %L0, 0"            "\n\t"
+                        "sll    %L0, %L0, 0"            "\n\t"
+                        ".set   pop"                    "\n"
+                        : "=r" (val)
+                        : "m" (*ptr));
+                local_irq_restore(flags);
+        } else
+                val = *ptr;
+
+        return val;
 }
 
 static inline void
@@ -102,7 +128,25 @@ nlm_write_reg64(uint64_t base, uint32_t reg, uint64_t val)
         uint64_t addr = base + (reg >> 1) * sizeof(uint64_t);
         volatile uint64_t *ptr = (volatile uint64_t *)(long)addr;
 
-        *ptr = val;
+        if (sizeof(unsigned long) == 4) {
+                unsigned long flags;
+                uint64_t tmp;
+
+                local_irq_save(flags);
+                __asm__ __volatile__(
+                        ".set   push"                   "\n\t"
+                        ".set   mips64"                 "\n\t"
+                        "dsll32 %L0, %L0, 0"            "\n\t"
+                        "dsrl32 %L0, %L0, 0"            "\n\t"
+                        "dsll32 %M0, %M0, 0"            "\n\t"
+                        "or     %L0, %L0, %M0"          "\n\t"
+                        "sd     %L0, %2"                "\n\t"
+                        ".set   pop"                    "\n"
+                        : "=r" (tmp)
+                        : "0" (val), "m" (*ptr));
+                local_irq_restore(flags);
+        } else
+                *ptr = val;
 }
 
 /*