arch/unicore32/kernel/fpu-ucf64.c

   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  */
  55 void 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  */
  78 void 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("UniCore-F64 Error: unhandled exceptions\n");
  94                 pr_debug("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  */
 117 static 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
 126 late_initcall(ucf64_init);