arch/riscv/kernel/time.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2012 Regents of the University of California
   4  * Copyright (C) 2017 SiFive
   5  */
   6
   7 #include <linux/acpi.h>
   8 #include <linux/of_clk.h>
   9 #include <linux/clockchips.h>
  10 #include <linux/clocksource.h>
  11 #include <linux/delay.h>
  12 #include <asm/sbi.h>
  13 #include <asm/processor.h>
  14 #include <asm/timex.h>
  15
  16 unsigned long riscv_timebase __ro_after_init;
  17 EXPORT_SYMBOL_GPL(riscv_timebase);
  18
  19 void __init time_init(void)
  20 {
  21         struct device_node *cpu;
  22         struct acpi_table_rhct *rhct;
  23         acpi_status status;
  24         u32 prop;
  25
  26         if (acpi_disabled) {
  27                 cpu = of_find_node_by_path("/cpus");
  28                 if (!cpu || of_property_read_u32(cpu, "timebase-frequency", &prop))
  29                         panic("RISC-V system with no 'timebase-frequency' in DTS\n");
  30
  31                 of_node_put(cpu);
  32                 riscv_timebase = prop;
  33                 of_clk_init(NULL);
  34         } else {
  35                 status = acpi_get_table(ACPI_SIG_RHCT, 0, (struct acpi_table_header **)&rhct);
  36                 if (ACPI_FAILURE(status))
  37                         panic("RISC-V ACPI system with no RHCT table\n");
  38
  39                 riscv_timebase = rhct->time_base_freq;
  40                 acpi_put_table((struct acpi_table_header *)rhct);
  41         }
  42
  43         lpj_fine = riscv_timebase / HZ;
  44
  45         timer_probe();
  46
  47         tick_setup_hrtimer_broadcast();
  48 }