1/*
2 * linux/arch/unicore32/kernel/fpu-ucf64.c
3 *
4 * Code specific to PKUnity SoC and UniCore ISA
5 *
6 * Copyright (C) 2001-2010 GUAN Xue-tao
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12#include <linux/module.h>
13#include <linux/types.h>
14#include <linux/kernel.h>
15#include <linux/signal.h>
16#include <linux/sched.h>
17#include <linux/init.h>
18
19#include <asm/fpu-ucf64.h>
20
21/*
22 * A special flag to tell the normalisation code not to normalise.
23 */
24#define F64_NAN_FLAG	0x100
25
26/*
27 * A bit pattern used to indicate the initial (unset) value of the
28 * exception mask, in case nothing handles an instruction.  This
29 * doesn't include the NAN flag, which get masked out before
30 * we check for an error.
31 */
32#define F64_EXCEPTION_ERROR	((u32)-1 & ~F64_NAN_FLAG)
33
34/*
35 * Since we aren't building with -mfpu=f64, we need to code
36 * these instructions using their MRC/MCR equivalents.
37 */
38#define f64reg(_f64_) #_f64_
39
40#define cff(_f64_) ({			\
41	u32 __v;			\
42	asm("cff %0, " f64reg(_f64_) "@ fmrx	%0, " #_f64_	\
43	    : "=r" (__v) : : "cc");	\
44	__v;				\
45	})
46
47#define ctf(_f64_, _var_)		\
48	asm("ctf %0, " f64reg(_f64_) "@ fmxr	" #_f64_ ", %0"	\
49	   : : "r" (_var_) : "cc")
50
51/*
52 * Raise a SIGFPE for the current process.
53 * sicode describes the signal being raised.
54 */
55void ucf64_raise_sigfpe(unsigned int sicode, struct pt_regs *regs)
56{
57	siginfo_t info;
58
59	memset(&info, 0, sizeof(info));
60
61	info.si_signo = SIGFPE;
62	info.si_code = sicode;
63	info.si_addr = (void __user *)(instruction_pointer(regs) - 4);
64
65	/*
66	 * This is the same as NWFPE, because it's not clear what
67	 * this is used for
68	 */
69	current->thread.error_code = 0;
70	current->thread.trap_no = 6;
71
72	send_sig_info(SIGFPE, &info, current);
73}
74
75/*
76 * Handle exceptions of UniCore-F64.
77 */
78void ucf64_exchandler(u32 inst, u32 fpexc, struct pt_regs *regs)
79{
80	u32 tmp = fpexc;
81	u32 exc = F64_EXCEPTION_ERROR & fpexc;
82
83	pr_debug("UniCore-F64: instruction %08x fpscr %08x\n",
84			inst, fpexc);
85
86	if (exc & FPSCR_CMPINSTR_BIT) {
87		if (exc & FPSCR_CON)
88			tmp |= FPSCR_CON;
89		else
90			tmp &= ~(FPSCR_CON);
91		exc &= ~(FPSCR_CMPINSTR_BIT | FPSCR_CON);
92	} else {
93		pr_debug(KERN_ERR "UniCore-F64 Error: unhandled exceptions\n");
94		pr_debug(KERN_ERR "UniCore-F64 FPSCR 0x%08x INST 0x%08x\n",
95				cff(FPSCR), inst);
96
97		ucf64_raise_sigfpe(0, regs);
98		return;
99	}
100
101	/*
102	 * Update the FPSCR with the additional exception flags.
103	 * Comparison instructions always return at least one of
104	 * these flags set.
105	 */
106	tmp &= ~(FPSCR_TRAP | FPSCR_IOS | FPSCR_OFS | FPSCR_UFS |
107			FPSCR_IXS | FPSCR_HIS | FPSCR_IOC | FPSCR_OFC |
108			FPSCR_UFC | FPSCR_IXC | FPSCR_HIC);
109
110	tmp |= exc;
111	ctf(FPSCR, tmp);
112}
113
114/*
115 * F64 support code initialisation.
116 */
117static int __init ucf64_init(void)
118{
119	ctf(FPSCR, 0x0);     /* FPSCR_UFE | FPSCR_NDE perhaps better */
120
121	printk(KERN_INFO "Enable UniCore-F64 support.\n");
122
123	return 0;
124}
125
126late_initcall(ucf64_init);
127