1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 *	O32 interface for the 64 (or N32) ABI.
4 *
5 *	Copyright (C) 2002, 2014  Maciej W. Rozycki
6 */
7
8#include <asm/asm.h>
9#include <asm/regdef.h>
10
11/* O32 register size.  */
12#define O32_SZREG	4
13/* Maximum number of arguments supported.  Must be even!  */
14#define O32_ARGC	32
15/* Number of static registers we save.  */
16#define O32_STATC	11
17/* Argument area frame size.  */
18#define O32_ARGSZ	(O32_SZREG * O32_ARGC)
19/* Static register save area frame size.  */
20#define O32_STATSZ	(SZREG * O32_STATC)
21/* Stack pointer register save area frame size.  */
22#define O32_SPSZ	SZREG
23/* Combined area frame size.  */
24#define O32_FRAMESZ	(O32_ARGSZ + O32_SPSZ + O32_STATSZ)
25/* Switched stack frame size.  */
26#define O32_NFRAMESZ	(O32_ARGSZ + O32_SPSZ)
27
28		.text
29
30/*
31 * O32 function call dispatcher, for interfacing 32-bit ROM routines.
32 *
33 * The standard 64 (N32) calling sequence is supported, with a0 holding
34 * a function pointer, a1 a pointer to the new stack to call the
35 * function with or 0 if no stack switching is requested, a2-a7 -- the
36 * function call's first six arguments, and the stack -- the remaining
37 * arguments (up to O32_ARGC, including a2-a7).  Static registers, gp
38 * and fp are preserved, v0 holds the result.  This code relies on the
39 * called o32 function for sp and ra restoration and this dispatcher has
40 * to be placed in a KSEGx (or KUSEG) address space.  Any pointers
41 * passed have to point to addresses within one of these spaces as well.
42 */
43NESTED(call_o32, O32_FRAMESZ, ra)
44		REG_SUBU	sp,O32_FRAMESZ
45
46		REG_S		ra,O32_FRAMESZ-1*SZREG(sp)
47		REG_S		fp,O32_FRAMESZ-2*SZREG(sp)
48		REG_S		gp,O32_FRAMESZ-3*SZREG(sp)
49		REG_S		s7,O32_FRAMESZ-4*SZREG(sp)
50		REG_S		s6,O32_FRAMESZ-5*SZREG(sp)
51		REG_S		s5,O32_FRAMESZ-6*SZREG(sp)
52		REG_S		s4,O32_FRAMESZ-7*SZREG(sp)
53		REG_S		s3,O32_FRAMESZ-8*SZREG(sp)
54		REG_S		s2,O32_FRAMESZ-9*SZREG(sp)
55		REG_S		s1,O32_FRAMESZ-10*SZREG(sp)
56		REG_S		s0,O32_FRAMESZ-11*SZREG(sp)
57
58		move		jp,a0
59
60		move		fp,sp
61		beqz		a1,0f
62		REG_SUBU	fp,a1,O32_NFRAMESZ
630:
64		REG_S		sp,O32_NFRAMESZ-1*SZREG(fp)
65
66		sll		a0,a2,zero
67		sll		a1,a3,zero
68		sll		a2,a4,zero
69		sll		a3,a5,zero
70		sw		a6,4*O32_SZREG(fp)
71		sw		a7,5*O32_SZREG(fp)
72
73		PTR_LA		t0,O32_FRAMESZ(sp)
74		PTR_LA		t1,6*O32_SZREG(fp)
75		li		t2,O32_ARGC-6
761:
77		lw		t3,(t0)
78		REG_ADDU	t0,SZREG
79		sw		t3,(t1)
80		REG_SUBU	t2,1
81		REG_ADDU	t1,O32_SZREG
82		bnez		t2,1b
83
84		move		sp,fp
85
86		jalr		jp
87
88		REG_L		sp,O32_NFRAMESZ-1*SZREG(sp)
89
90		REG_L		s0,O32_FRAMESZ-11*SZREG(sp)
91		REG_L		s1,O32_FRAMESZ-10*SZREG(sp)
92		REG_L		s2,O32_FRAMESZ-9*SZREG(sp)
93		REG_L		s3,O32_FRAMESZ-8*SZREG(sp)
94		REG_L		s4,O32_FRAMESZ-7*SZREG(sp)
95		REG_L		s5,O32_FRAMESZ-6*SZREG(sp)
96		REG_L		s6,O32_FRAMESZ-5*SZREG(sp)
97		REG_L		s7,O32_FRAMESZ-4*SZREG(sp)
98		REG_L		gp,O32_FRAMESZ-3*SZREG(sp)
99		REG_L		fp,O32_FRAMESZ-2*SZREG(sp)
100		REG_L		ra,O32_FRAMESZ-1*SZREG(sp)
101
102		REG_ADDU	sp,O32_FRAMESZ
103		jr		ra
104END(call_o32)
105