drivers/clocksource/numachip.c

   1 /*
   2  *
   3  * Copyright (C) 2015 Numascale AS. All rights reserved.
   4  *
   5  * This software is licensed under the terms of the GNU General Public
   6  * License version 2, as published by the Free Software Foundation, and
   7  * may be copied, distributed, and modified under those terms.
   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  */
  15
  16 #include <linux/clockchips.h>
  17
  18 #include <asm/irq.h>
  19 #include <asm/numachip/numachip.h>
  20 #include <asm/numachip/numachip_csr.h>
  21
  22 static DEFINE_PER_CPU(struct clock_event_device, numachip2_ced);
  23
  24 static cycles_t numachip2_timer_read(struct clocksource *cs)
  25 {
  26         return numachip2_read64_lcsr(NUMACHIP2_TIMER_NOW);
  27 }
  28
  29 static struct clocksource numachip2_clocksource = {
  30         .name            = "numachip2",
  31         .rating          = 295,
  32         .read            = numachip2_timer_read,
  33         .mask            = CLOCKSOURCE_MASK(64),
  34         .flags           = CLOCK_SOURCE_IS_CONTINUOUS,
  35         .mult            = 1,
  36         .shift           = 0,
  37 };
  38
  39 static int numachip2_set_next_event(unsigned long delta, struct clock_event_device *ced)
  40 {
  41         numachip2_write64_lcsr(NUMACHIP2_TIMER_DEADLINE + numachip2_timer(),
  42                 delta);
  43         return 0;
  44 }
  45
  46 static struct clock_event_device numachip2_clockevent = {
  47         .name            = "numachip2",
  48         .rating          = 400,
  49         .set_next_event  = numachip2_set_next_event,
  50         .features        = CLOCK_EVT_FEAT_ONESHOT,
  51         .mult            = 1,
  52         .shift           = 0,
  53         .min_delta_ns    = 1250,
  54         .max_delta_ns    = LONG_MAX,
  55 };
  56
  57 static void numachip_timer_interrupt(void)
  58 {
  59         struct clock_event_device *ced = this_cpu_ptr(&numachip2_ced);
  60
  61         ced->event_handler(ced);
  62 }
  63
  64 static __init void numachip_timer_each(struct work_struct *work)
  65 {
  66         unsigned local_apicid = __this_cpu_read(x86_cpu_to_apicid) & 0xff;
  67         struct clock_event_device *ced = this_cpu_ptr(&numachip2_ced);
  68
  69         /* Setup IPI vector to local core and relative timing mode */
  70         numachip2_write64_lcsr(NUMACHIP2_TIMER_INT + numachip2_timer(),
  71                 (3 << 22) | (X86_PLATFORM_IPI_VECTOR << 14) |
  72                 (local_apicid << 6));
  73
  74         *ced = numachip2_clockevent;
  75         ced->cpumask = cpumask_of(smp_processor_id());
  76         clockevents_register_device(ced);
  77 }
  78
  79 static int __init numachip_timer_init(void)
  80 {
  81         if (numachip_system != 2)
  82                 return -ENODEV;
  83
  84         /* Reset timer */
  85         numachip2_write64_lcsr(NUMACHIP2_TIMER_RESET, 0);
  86         clocksource_register_hz(&numachip2_clocksource, NSEC_PER_SEC);
  87
  88         /* Setup per-cpu clockevents */
  89         x86_platform_ipi_callback = numachip_timer_interrupt;
  90         schedule_on_each_cpu(&numachip_timer_each);
  91
  92         return 0;
  93 }
  94
  95 arch_initcall(numachip_timer_init);