drivers/clocksource/numachip.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *
   4  * Copyright (C) 2015 Numascale AS. All rights reserved.
   5  */
   6
   7 #include <linux/clockchips.h>
   8
   9 #include <asm/irq.h>
  10 #include <asm/numachip/numachip.h>
  11 #include <asm/numachip/numachip_csr.h>
  12
  13 static DEFINE_PER_CPU(struct clock_event_device, numachip2_ced);
  14
  15 static cycles_t numachip2_timer_read(struct clocksource *cs)
  16 {
  17         return numachip2_read64_lcsr(NUMACHIP2_TIMER_NOW);
  18 }
  19
  20 static struct clocksource numachip2_clocksource = {
  21         .name            = "numachip2",
  22         .rating          = 295,
  23         .read            = numachip2_timer_read,
  24         .mask            = CLOCKSOURCE_MASK(64),
  25         .flags           = CLOCK_SOURCE_IS_CONTINUOUS,
  26         .mult            = 1,
  27         .shift           = 0,
  28 };
  29
  30 static int numachip2_set_next_event(unsigned long delta, struct clock_event_device *ced)
  31 {
  32         numachip2_write64_lcsr(NUMACHIP2_TIMER_DEADLINE + numachip2_timer(),
  33                 delta);
  34         return 0;
  35 }
  36
  37 static const struct clock_event_device numachip2_clockevent __initconst = {
  38         .name            = "numachip2",
  39         .rating          = 400,
  40         .set_next_event  = numachip2_set_next_event,
  41         .features        = CLOCK_EVT_FEAT_ONESHOT,
  42         .mult            = 1,
  43         .shift           = 0,
  44         .min_delta_ns    = 1250,
  45         .min_delta_ticks = 1250,
  46         .max_delta_ns    = LONG_MAX,
  47         .max_delta_ticks = LONG_MAX,
  48 };
  49
  50 static void numachip_timer_interrupt(void)
  51 {
  52         struct clock_event_device *ced = this_cpu_ptr(&numachip2_ced);
  53
  54         ced->event_handler(ced);
  55 }
  56
  57 static __init void numachip_timer_each(struct work_struct *work)
  58 {
  59         unsigned local_apicid = __this_cpu_read(x86_cpu_to_apicid) & 0xff;
  60         struct clock_event_device *ced = this_cpu_ptr(&numachip2_ced);
  61
  62         /* Setup IPI vector to local core and relative timing mode */
  63         numachip2_write64_lcsr(NUMACHIP2_TIMER_INT + numachip2_timer(),
  64                 (3 << 22) | (X86_PLATFORM_IPI_VECTOR << 14) |
  65                 (local_apicid << 6));
  66
  67         *ced = numachip2_clockevent;
  68         ced->cpumask = cpumask_of(smp_processor_id());
  69         clockevents_register_device(ced);
  70 }
  71
  72 static int __init numachip_timer_init(void)
  73 {
  74         if (numachip_system != 2)
  75                 return -ENODEV;
  76
  77         /* Reset timer */
  78         numachip2_write64_lcsr(NUMACHIP2_TIMER_RESET, 0);
  79         clocksource_register_hz(&numachip2_clocksource, NSEC_PER_SEC);
  80
  81         /* Setup per-cpu clockevents */
  82         x86_platform_ipi_callback = numachip_timer_interrupt;
  83         schedule_on_each_cpu(&numachip_timer_each);
  84
  85         return 0;
  86 }
  87
  88 arch_initcall(numachip_timer_init);