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 #include <asm/paravirt.h>
  16
  17 unsigned long riscv_timebase __ro_after_init;
  18 EXPORT_SYMBOL_GPL(riscv_timebase);
  19
  20 void __init time_init(void)
  21 {
  22         struct device_node *cpu;
  23         struct acpi_table_rhct *rhct;
  24         acpi_status status;
  25         u32 prop;
  26
  27         if (acpi_disabled) {
  28                 cpu = of_find_node_by_path("/cpus");
  29                 if (!cpu || of_property_read_u32(cpu, "timebase-frequency", &prop))
  30                         panic("RISC-V system with no 'timebase-frequency' in DTS\n");
  31
  32                 of_node_put(cpu);
  33                 riscv_timebase = prop;
  34                 of_clk_init(NULL);
  35         } else {
  36                 status = acpi_get_table(ACPI_SIG_RHCT, 0, (struct acpi_table_header **)&rhct);
  37                 if (ACPI_FAILURE(status))
  38                         panic("RISC-V ACPI system with no RHCT table\n");
  39
  40                 riscv_timebase = rhct->time_base_freq;
  41                 acpi_put_table((struct acpi_table_header *)rhct);
  42         }
  43
  44         lpj_fine = riscv_timebase / HZ;
  45
  46         timer_probe();
  47
  48         tick_setup_hrtimer_broadcast();
  49
  50         pv_time_init();
  51 }