1  /* Copyright (C) 2013-2023 Free Software Foundation, Inc.
       2     Contributed by Altera and Mentor Graphics, Inc.
       3  
       4  This file is free software; you can redistribute it and/or modify it
       5  under the terms of the GNU General Public License as published by the
       6  Free Software Foundation; either version 3, or (at your option) any
       7  later version.
       8  
       9  This file is distributed in the hope that it will be useful, but
      10  WITHOUT ANY WARRANTY; without even the implied warranty of
      11  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      12  General Public License for more details.
      13  
      14  Under Section 7 of GPL version 3, you are granted additional
      15  permissions described in the GCC Runtime Library Exception, version
      16  3.1, as published by the Free Software Foundation.
      17  
      18  You should have received a copy of the GNU General Public License and
      19  a copy of the GCC Runtime Library Exception along with this program;
      20  see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
      21  <http://www.gnu.org/licenses/>.  */
      22  
      23  /* Set up trampolines.
      24     R12 is the static chain register.
      25     R2 is AT, the assembler temporary.
      26     The trampoline code looks like:
      27  	movhi	r12,%hi(chain)
      28  	ori	r12,%lo(chain)
      29  	movhi	r2,%hi(fn)
      30  	ori	r2,%lo(fn)
      31  	jmp	r2
      32  */
      33  
      34  #define SC_REGNO 12
      35  
      36  /* Instruction encodings depend on the ISA level.  */
      37  #if __nios2_arch__ == 2
      38  #define MOVHI(reg,imm16)			\
      39    (((reg) << 11) | ((imm16) << 16) | 0x34)
      40  #define ORI(reg,imm16)						\
      41    (((reg) << 11) | ((reg) << 6) | ((imm16) << 16) | 0x14)
      42  #define JMP(reg)				\
      43    (((reg) << 6) | (0x0d << 26) | 0x20)
      44  
      45  #elif __nios2_arch__ == 1
      46  #define MOVHI(reg,imm16)			\
      47    (((reg) << 22) | ((imm16) << 6) | 0x34)
      48  #define ORI(reg,imm16)						\
      49    (((reg) << 27) | ((reg) << 22) | ((imm16) << 6) | 0x14)
      50  #define JMP(reg)				\
      51    (((reg) << 27) | (0x0d << 11) | 0x3a)
      52  
      53  #else
      54  #error "Unknown Nios II architecture level"
      55  #endif
      56  
      57  void
      58  __trampoline_setup (unsigned int *addr, void *fnptr, void *chainptr)
      59  {
      60    unsigned int fn = (unsigned int) fnptr;
      61    unsigned int chain = (unsigned int) chainptr;
      62    int i;
      63  
      64    addr[0] = MOVHI (SC_REGNO, ((chain >> 16) & 0xffff));
      65    addr[1] = ORI (SC_REGNO, (chain & 0xffff));
      66    addr[2] = MOVHI (2, ((fn >> 16) & 0xffff));
      67    addr[3] = ORI (2, (fn & 0xffff));
      68    addr[4] = JMP (2);
      69  
      70    /* Flush the caches.
      71       See Example 9-4 in the Nios II Software Developer's Handbook.  */
      72    for (i = 0; i < 5; i++)
      73      asm volatile ("flushd 0(%0); flushi %0" :: "r"(addr + i) : "memory");
      74    asm volatile ("flushp" ::: "memory");
      75  }