arch/loongarch/kernel/time.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Common time service routines for LoongArch machines.
   4  *
   5  * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
   6  */
   7 #include <linux/clockchips.h>
   8 #include <linux/delay.h>
   9 #include <linux/export.h>
  10 #include <linux/init.h>
  11 #include <linux/interrupt.h>
  12 #include <linux/kernel.h>
  13 #include <linux/sched_clock.h>
  14 #include <linux/spinlock.h>
  15
  16 #include <asm/cpu-features.h>
  17 #include <asm/loongarch.h>
  18 #include <asm/time.h>
  19
  20 u64 cpu_clock_freq;
  21 EXPORT_SYMBOL(cpu_clock_freq);
  22 u64 const_clock_freq;
  23 EXPORT_SYMBOL(const_clock_freq);
  24
  25 static DEFINE_RAW_SPINLOCK(state_lock);
  26 static DEFINE_PER_CPU(struct clock_event_device, constant_clockevent_device);
  27
  28 static void constant_event_handler(struct clock_event_device *dev)
  29 {
  30 }
  31
  32 irqreturn_t constant_timer_interrupt(int irq, void *data)
  33 {
  34         int cpu = smp_processor_id();
  35         struct clock_event_device *cd;
  36
  37         /* Clear Timer Interrupt */
  38         write_csr_tintclear(CSR_TINTCLR_TI);
  39         cd = &per_cpu(constant_clockevent_device, cpu);
  40         cd->event_handler(cd);
  41
  42         return IRQ_HANDLED;
  43 }
  44
  45 static int constant_set_state_oneshot(struct clock_event_device *evt)
  46 {
  47         unsigned long timer_config;
  48
  49         raw_spin_lock(&state_lock);
  50
  51         timer_config = csr_read64(LOONGARCH_CSR_TCFG);
  52         timer_config |= CSR_TCFG_EN;
  53         timer_config &= ~CSR_TCFG_PERIOD;
  54         csr_write64(timer_config, LOONGARCH_CSR_TCFG);
  55
  56         raw_spin_unlock(&state_lock);
  57
  58         return 0;
  59 }
  60
  61 static int constant_set_state_periodic(struct clock_event_device *evt)
  62 {
  63         unsigned long period;
  64         unsigned long timer_config;
  65
  66         raw_spin_lock(&state_lock);
  67
  68         period = const_clock_freq / HZ;
  69         timer_config = period & CSR_TCFG_VAL;
  70         timer_config |= (CSR_TCFG_PERIOD | CSR_TCFG_EN);
  71         csr_write64(timer_config, LOONGARCH_CSR_TCFG);
  72
  73         raw_spin_unlock(&state_lock);
  74
  75         return 0;
  76 }
  77
  78 static int constant_set_state_shutdown(struct clock_event_device *evt)
  79 {
  80         unsigned long timer_config;
  81
  82         raw_spin_lock(&state_lock);
  83
  84         timer_config = csr_read64(LOONGARCH_CSR_TCFG);
  85         timer_config &= ~CSR_TCFG_EN;
  86         csr_write64(timer_config, LOONGARCH_CSR_TCFG);
  87
  88         raw_spin_unlock(&state_lock);
  89
  90         return 0;
  91 }
  92
  93 static int constant_timer_next_event(unsigned long delta, struct clock_event_device *evt)
  94 {
  95         unsigned long timer_config;
  96
  97         delta &= CSR_TCFG_VAL;
  98         timer_config = delta | CSR_TCFG_EN;
  99         csr_write64(timer_config, LOONGARCH_CSR_TCFG);
 100
 101         return 0;
 102 }
 103
 104 static unsigned long __init get_loops_per_jiffy(void)
 105 {
 106         unsigned long lpj = (unsigned long)const_clock_freq;
 107
 108         do_div(lpj, HZ);
 109
 110         return lpj;
 111 }
 112
 113 static long init_timeval;
 114
 115 void sync_counter(void)
 116 {
 117         /* Ensure counter begin at 0 */
 118         csr_write64(-init_timeval, LOONGARCH_CSR_CNTC);
 119 }
 120
 121 static int get_timer_irq(void)
 122 {
 123         struct irq_domain *d = irq_find_matching_fwnode(cpuintc_handle, DOMAIN_BUS_ANY);
 124
 125         if (d)
 126                 return irq_create_mapping(d, EXCCODE_TIMER - EXCCODE_INT_START);
 127
 128         return -EINVAL;
 129 }
 130
 131 int constant_clockevent_init(void)
 132 {
 133         unsigned int cpu = smp_processor_id();
 134         unsigned long min_delta = 0x600;
 135         unsigned long max_delta = (1UL << 48) - 1;
 136         struct clock_event_device *cd;
 137         static int irq = 0, timer_irq_installed = 0;
 138
 139         if (!timer_irq_installed) {
 140                 irq = get_timer_irq();
 141                 if (irq < 0)
 142                         pr_err("Failed to map irq %d (timer)\n", irq);
 143         }
 144
 145         cd = &per_cpu(constant_clockevent_device, cpu);
 146
 147         cd->name = "Constant";
 148         cd->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_PERCPU;
 149
 150         cd->irq = irq;
 151         cd->rating = 320;
 152         cd->cpumask = cpumask_of(cpu);
 153         cd->set_state_oneshot = constant_set_state_oneshot;
 154         cd->set_state_oneshot_stopped = constant_set_state_shutdown;
 155         cd->set_state_periodic = constant_set_state_periodic;
 156         cd->set_state_shutdown = constant_set_state_shutdown;
 157         cd->set_next_event = constant_timer_next_event;
 158         cd->event_handler = constant_event_handler;
 159
 160         clockevents_config_and_register(cd, const_clock_freq, min_delta, max_delta);
 161
 162         if (timer_irq_installed)
 163                 return 0;
 164
 165         timer_irq_installed = 1;
 166
 167         sync_counter();
 168
 169         if (request_irq(irq, constant_timer_interrupt, IRQF_PERCPU | IRQF_TIMER, "timer", NULL))
 170                 pr_err("Failed to request irq %d (timer)\n", irq);
 171
 172         lpj_fine = get_loops_per_jiffy();
 173         pr_info("Constant clock event device register\n");
 174
 175         return 0;
 176 }
 177
 178 static u64 read_const_counter(struct clocksource *clk)
 179 {
 180         return drdtime();
 181 }
 182
 183 static u64 native_sched_clock(void)
 184 {
 185         return read_const_counter(NULL);
 186 }
 187
 188 static struct clocksource clocksource_const = {
 189         .name = "Constant",
 190         .rating = 400,
 191         .read = read_const_counter,
 192         .mask = CLOCKSOURCE_MASK(64),
 193         .flags = CLOCK_SOURCE_IS_CONTINUOUS,
 194         .vdso_clock_mode = VDSO_CLOCKMODE_CPU,
 195 };
 196
 197 int __init constant_clocksource_init(void)
 198 {
 199         int res;
 200         unsigned long freq = const_clock_freq;
 201
 202         res = clocksource_register_hz(&clocksource_const, freq);
 203
 204         sched_clock_register(native_sched_clock, 64, freq);
 205
 206         pr_info("Constant clock source device register\n");
 207
 208         return res;
 209 }
 210
 211 void __init time_init(void)
 212 {
 213         if (!cpu_has_cpucfg)
 214                 const_clock_freq = cpu_clock_freq;
 215         else
 216                 const_clock_freq = calc_const_freq();
 217
 218         init_timeval = drdtime() - csr_read64(LOONGARCH_CSR_CNTC);
 219
 220         constant_clockevent_init();
 221         constant_clocksource_init();
 222 }