arch/mips/kernel/csrc-sb1250.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2000, 2001 Broadcom Corporation
   4  */
   5 #include <linux/clocksource.h>
   6 #include <linux/sched_clock.h>
   7
   8 #include <asm/addrspace.h>
   9 #include <asm/io.h>
  10 #include <asm/time.h>
  11
  12 #include <asm/sibyte/sb1250.h>
  13 #include <asm/sibyte/sb1250_regs.h>
  14 #include <asm/sibyte/sb1250_int.h>
  15 #include <asm/sibyte/sb1250_scd.h>
  16
  17 #define SB1250_HPT_NUM          3
  18 #define SB1250_HPT_VALUE        M_SCD_TIMER_CNT /* max value */
  19
  20 /*
  21  * The HPT is free running from SB1250_HPT_VALUE down to 0 then starts over
  22  * again.
  23  */
  24 static inline u64 sb1250_hpt_get_cycles(void)
  25 {
  26         unsigned int count;
  27         void __iomem *addr;
  28
  29         addr = IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM, R_SCD_TIMER_CNT));
  30         count = G_SCD_TIMER_CNT(__raw_readq(addr));
  31
  32         return SB1250_HPT_VALUE - count;
  33 }
  34
  35 static u64 sb1250_hpt_read(struct clocksource *cs)
  36 {
  37         return sb1250_hpt_get_cycles();
  38 }
  39
  40 struct clocksource bcm1250_clocksource = {
  41         .name   = "bcm1250-counter-3",
  42         .rating = 200,
  43         .read   = sb1250_hpt_read,
  44         .mask   = CLOCKSOURCE_MASK(23),
  45         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
  46 };
  47
  48 static u64 notrace sb1250_read_sched_clock(void)
  49 {
  50         return sb1250_hpt_get_cycles();
  51 }
  52
  53 void __init sb1250_clocksource_init(void)
  54 {
  55         struct clocksource *cs = &bcm1250_clocksource;
  56
  57         /* Setup hpt using timer #3 but do not enable irq for it */
  58         __raw_writeq(0,
  59                      IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM,
  60                                                  R_SCD_TIMER_CFG)));
  61         __raw_writeq(SB1250_HPT_VALUE,
  62                      IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM,
  63                                                  R_SCD_TIMER_INIT)));
  64         __raw_writeq(M_SCD_TIMER_ENABLE | M_SCD_TIMER_MODE_CONTINUOUS,
  65                      IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM,
  66                                                  R_SCD_TIMER_CFG)));
  67
  68         clocksource_register_hz(cs, V_SCD_TIMER_FREQ);
  69
  70         sched_clock_register(sb1250_read_sched_clock, 23, V_SCD_TIMER_FREQ);
  71 }