arch/alpha/oprofile/op_model_ev4.c

   1 /**
   2  * @file arch/alpha/oprofile/op_model_ev4.c
   3  *
   4  * @remark Copyright 2002 OProfile authors
   5  * @remark Read the file COPYING
   6  *
   7  * @author Richard Henderson <rth@twiddle.net>
   8  */
   9
  10 #include <linux/oprofile.h>
  11 #include <linux/init.h>
  12 #include <linux/smp.h>
  13 #include <asm/ptrace.h>
  14
  15 #include "op_impl.h"
  16
  17
  18 /* Compute all of the registers in preparation for enabling profiling.  */
  19
  20 static void
  21 ev4_reg_setup(struct op_register_config *reg,
  22               struct op_counter_config *ctr,
  23               struct op_system_config *sys)
  24 {
  25         unsigned long ctl = 0, count, hilo;
  26
  27         /* Select desired events.  We've mapped the event numbers
  28            such that they fit directly into the event selection fields.
  29
  30            Note that there is no "off" setting.  In both cases we select
  31            the EXTERNAL event source, hoping that it'll be the lowest
  32            frequency, and set the frequency counter to LOW.  The interrupts
  33            for these "disabled" counter overflows are ignored by the
  34            interrupt handler.
  35
  36            This is most irritating, because the hardware *can* enable and
  37            disable the interrupts for these counters independently, but the
  38            wrperfmon interface doesn't allow it.  */
  39
  40         ctl |= (ctr[0].enabled ? ctr[0].event << 8 : 14 << 8);
  41         ctl |= (ctr[1].enabled ? (ctr[1].event - 16) << 32 : 7ul << 32);
  42
  43         /* EV4 can not read or write its counter registers.  The only
  44            thing one can do at all is see if you overflow and get an
  45            interrupt.  We can set the width of the counters, to some
  46            extent.  Take the interrupt count selected by the user,
  47            map it onto one of the possible values, and write it back.  */
  48
  49         count = ctr[0].count;
  50         if (count <= 4096)
  51                 count = 4096, hilo = 1;
  52         else
  53                 count = 65536, hilo = 0;
  54         ctr[0].count = count;
  55         ctl |= (ctr[0].enabled && hilo) << 3;
  56
  57         count = ctr[1].count;
  58         if (count <= 256)
  59                 count = 256, hilo = 1;
  60         else
  61                 count = 4096, hilo = 0;
  62         ctr[1].count = count;
  63         ctl |= (ctr[1].enabled && hilo);
  64
  65         reg->mux_select = ctl;
  66
  67         /* Select performance monitoring options.  */
  68         /* ??? Need to come up with some mechanism to trace only
  69            selected processes.  EV4 does not have a mechanism to
  70            select kernel or user mode only.  For now, enable always.  */
  71         reg->proc_mode = 0;
  72
  73         /* Frequency is folded into mux_select for EV4.  */
  74         reg->freq = 0;
  75
  76         /* See above regarding no writes.  */
  77         reg->reset_values = 0;
  78         reg->need_reset = 0;
  79
  80 }
  81
  82 /* Program all of the registers in preparation for enabling profiling.  */
  83
  84 static void
  85 ev4_cpu_setup(void *x)
  86 {
  87         struct op_register_config *reg = x;
  88
  89         wrperfmon(2, reg->mux_select);
  90         wrperfmon(3, reg->proc_mode);
  91 }
  92
  93 static void
  94 ev4_handle_interrupt(unsigned long which, struct pt_regs *regs,
  95                      struct op_counter_config *ctr)
  96 {
  97         /* EV4 can't properly disable counters individually.
  98            Discard "disabled" events now.  */
  99         if (!ctr[which].enabled)
 100                 return;
 101
 102         /* Record the sample.  */
 103         oprofile_add_sample(regs, which);
 104 }
 105
 106
 107 struct op_axp_model op_model_ev4 = {
 108         .reg_setup              = ev4_reg_setup,
 109         .cpu_setup              = ev4_cpu_setup,
 110         .reset_ctr              = NULL,
 111         .handle_interrupt       = ev4_handle_interrupt,
 112         .cpu_type               = "alpha/ev4",
 113         .num_counters           = 2,
 114         .can_set_proc_mode      = 0,
 115 };