arch/mips/kernel/csrc-sb1250.c

   1 /*
   2  * Copyright (C) 2000, 2001 Broadcom Corporation
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14 #include <linux/clocksource.h>
  15 #include <linux/sched_clock.h>
  16
  17 #include <asm/addrspace.h>
  18 #include <asm/io.h>
  19 #include <asm/time.h>
  20
  21 #include <asm/sibyte/sb1250.h>
  22 #include <asm/sibyte/sb1250_regs.h>
  23 #include <asm/sibyte/sb1250_int.h>
  24 #include <asm/sibyte/sb1250_scd.h>
  25
  26 #define SB1250_HPT_NUM          3
  27 #define SB1250_HPT_VALUE        M_SCD_TIMER_CNT /* max value */
  28
  29 /*
  30  * The HPT is free running from SB1250_HPT_VALUE down to 0 then starts over
  31  * again.
  32  */
  33 static inline u64 sb1250_hpt_get_cycles(void)
  34 {
  35         unsigned int count;
  36         void __iomem *addr;
  37
  38         addr = IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM, R_SCD_TIMER_CNT));
  39         count = G_SCD_TIMER_CNT(__raw_readq(addr));
  40
  41         return SB1250_HPT_VALUE - count;
  42 }
  43
  44 static u64 sb1250_hpt_read(struct clocksource *cs)
  45 {
  46         return sb1250_hpt_get_cycles();
  47 }
  48
  49 struct clocksource bcm1250_clocksource = {
  50         .name   = "bcm1250-counter-3",
  51         .rating = 200,
  52         .read   = sb1250_hpt_read,
  53         .mask   = CLOCKSOURCE_MASK(23),
  54         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
  55 };
  56
  57 static u64 notrace sb1250_read_sched_clock(void)
  58 {
  59         return sb1250_hpt_get_cycles();
  60 }
  61
  62 void __init sb1250_clocksource_init(void)
  63 {
  64         struct clocksource *cs = &bcm1250_clocksource;
  65
  66         /* Setup hpt using timer #3 but do not enable irq for it */
  67         __raw_writeq(0,
  68                      IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM,
  69                                                  R_SCD_TIMER_CFG)));
  70         __raw_writeq(SB1250_HPT_VALUE,
  71                      IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM,
  72                                                  R_SCD_TIMER_INIT)));
  73         __raw_writeq(M_SCD_TIMER_ENABLE | M_SCD_TIMER_MODE_CONTINUOUS,
  74                      IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM,
  75                                                  R_SCD_TIMER_CFG)));
  76
  77         clocksource_register_hz(cs, V_SCD_TIMER_FREQ);
  78
  79         sched_clock_register(sb1250_read_sched_clock, 23, V_SCD_TIMER_FREQ);
  80 }