MIPS: Add helpers for assembler macro instructions

[linux.git] / arch / mips / include / asm / mipsregs.h

diff --git a/arch/mips/include/asm/mipsregs.h b/arch/mips/include/asm/mipsregs.h
index 7a59ad6e7f7d9d7e21a9ea727c38d4b2fb95dbc7..ac70613fd3b87eb37cc0ad14d245d7f7df2a5e7e 100644 (file)
--- a/arch/mips/include/asm/mipsregs.h
+++ b/arch/mips/include/asm/mipsregs.h
@@ -1180,6 +1180,89 @@ static inline int mm_insn_16bit(u16 insn)
 #define _ASM_INSN_IF_MIPS(_enc)
 #endif
 
+/*
+ * parse_r var, r - Helper assembler macro for parsing register names.
+ *
+ * This converts the register name in $n form provided in \r to the
+ * corresponding register number, which is assigned to the variable \var. It is
+ * needed to allow explicit encoding of instructions in inline assembly where
+ * registers are chosen by the compiler in $n form, allowing us to avoid using
+ * fixed register numbers.
+ *
+ * It also allows newer instructions (not implemented by the assembler) to be
+ * transparently implemented using assembler macros, instead of needing separate
+ * cases depending on toolchain support.
+ *
+ * Simple usage example:
+ * __asm__ __volatile__("parse_r __rt, %0\n\t"
+ *                     ".insn\n\t"
+ *                     "# di    %0\n\t"
+ *                     ".word   (0x41606000 | (__rt << 16))"
+ *                     : "=r" (status);
+ */
+
+/* Match an individual register number and assign to \var */
+#define _IFC_REG(n)                            \
+       ".ifc   \\r, $" #n "\n\t"               \
+       "\\var  = " #n "\n\t"                   \
+       ".endif\n\t"
+
+__asm__(".macro        parse_r var r\n\t"
+       "\\var  = -1\n\t"
+       _IFC_REG(0)  _IFC_REG(1)  _IFC_REG(2)  _IFC_REG(3)
+       _IFC_REG(4)  _IFC_REG(5)  _IFC_REG(6)  _IFC_REG(7)
+       _IFC_REG(8)  _IFC_REG(9)  _IFC_REG(10) _IFC_REG(11)
+       _IFC_REG(12) _IFC_REG(13) _IFC_REG(14) _IFC_REG(15)
+       _IFC_REG(16) _IFC_REG(17) _IFC_REG(18) _IFC_REG(19)
+       _IFC_REG(20) _IFC_REG(21) _IFC_REG(22) _IFC_REG(23)
+       _IFC_REG(24) _IFC_REG(25) _IFC_REG(26) _IFC_REG(27)
+       _IFC_REG(28) _IFC_REG(29) _IFC_REG(30) _IFC_REG(31)
+       ".iflt  \\var\n\t"
+       ".error \"Unable to parse register name \\r\"\n\t"
+       ".endif\n\t"
+       ".endm");
+
+#undef _IFC_REG
+
+/*
+ * C macros for generating assembler macros for common instruction formats.
+ *
+ * The names of the operands can be chosen by the caller, and the encoding of
+ * register operand \<Rn> is assigned to __<Rn> where it can be accessed from
+ * the ENC encodings.
+ */
+
+/* Instructions with no operands */
+#define _ASM_MACRO_0(OP, ENC)                                          \
+       __asm__(".macro " #OP "\n\t"                                    \
+               ENC                                                     \
+               ".endm")
+
+/* Instructions with 2 register operands */
+#define _ASM_MACRO_2R(OP, R1, R2, ENC)                                 \
+       __asm__(".macro " #OP " " #R1 ", " #R2 "\n\t"                   \
+               "parse_r __" #R1 ", \\" #R1 "\n\t"                      \
+               "parse_r __" #R2 ", \\" #R2 "\n\t"                      \
+               ENC                                                     \
+               ".endm")
+
+/* Instructions with 3 register operands */
+#define _ASM_MACRO_3R(OP, R1, R2, R3, ENC)                             \
+       __asm__(".macro " #OP " " #R1 ", " #R2 ", " #R3 "\n\t"          \
+               "parse_r __" #R1 ", \\" #R1 "\n\t"                      \
+               "parse_r __" #R2 ", \\" #R2 "\n\t"                      \
+               "parse_r __" #R3 ", \\" #R3 "\n\t"                      \
+               ENC                                                     \
+               ".endm")
+
+/* Instructions with 2 register operands and 1 optional select operand */
+#define _ASM_MACRO_2R_1S(OP, R1, R2, SEL3, ENC)                                \
+       __asm__(".macro " #OP " " #R1 ", " #R2 ", " #SEL3 " = 0\n\t"    \
+               "parse_r __" #R1 ", \\" #R1 "\n\t"                      \
+               "parse_r __" #R2 ", \\" #R2 "\n\t"                      \
+               ENC                                                     \
+               ".endm")
+
 /*
  * TLB Invalidate Flush
  */