LXR linux/arch/arm/mach-shmobile/timer.c

   1/*
   2 * SH-Mobile Timer
   3 *
   4 * Copyright (C) 2010  Magnus Damm
   5 * Copyright (C) 2002 - 2009  Paul Mundt
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License as published by
   9 * the Free Software Foundation; version 2 of the License.
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 */
  16#include <linux/platform_device.h>
  17#include <linux/clocksource.h>
  18#include <linux/delay.h>
  19#include <linux/of_address.h>
  20
  21static void __init shmobile_setup_delay_hz(unsigned int max_cpu_core_hz,
  22                                           unsigned int mult, unsigned int div)
  23{
  24        /* calculate a worst-case loops-per-jiffy value
  25         * based on maximum cpu core hz setting and the
  26         * __delay() implementation in arch/arm/lib/delay.S
  27         *
  28         * this will result in a longer delay than expected
  29         * when the cpu core runs on lower frequencies.
  30         */
  31
  32        unsigned int value = HZ * div / mult;
  33
  34        if (!preset_lpj)
  35                preset_lpj = max_cpu_core_hz / value;
  36}
  37
  38void __init shmobile_init_delay(void)
  39{
  40        struct device_node *np, *cpus;
  41        bool is_a7_a8_a9 = false;
  42        bool is_a15 = false;
  43        bool has_arch_timer = false;
  44        u32 max_freq = 0;
  45
  46        cpus = of_find_node_by_path("/cpus");
  47        if (!cpus)
  48                return;
  49
  50        for_each_child_of_node(cpus, np) {
  51                u32 freq;
  52
  53                if (!of_property_read_u32(np, "clock-frequency", &freq))
  54                        max_freq = max(max_freq, freq);
  55
  56                if (of_device_is_compatible(np, "arm,cortex-a8") ||
  57                    of_device_is_compatible(np, "arm,cortex-a9")) {
  58                        is_a7_a8_a9 = true;
  59                } else if (of_device_is_compatible(np, "arm,cortex-a7")) {
  60                        is_a7_a8_a9 = true;
  61                        has_arch_timer = true;
  62                } else if (of_device_is_compatible(np, "arm,cortex-a15")) {
  63                        is_a15 = true;
  64                        has_arch_timer = true;
  65                }
  66        }
  67
  68        of_node_put(cpus);
  69
  70        if (!max_freq)
  71                return;
  72
  73#ifdef CONFIG_ARCH_SHMOBILE_LEGACY
  74        /* Non-multiplatform r8a73a4 SoC cannot use arch timer due
  75         * to GIC being initialized from C and arch timer via DT */
  76        if (of_machine_is_compatible("renesas,r8a73a4"))
  77                has_arch_timer = false;
  78
  79        /* Non-multiplatform r8a7790 SoC cannot use arch timer due
  80         * to GIC being initialized from C and arch timer via DT */
  81        if (of_machine_is_compatible("renesas,r8a7790"))
  82                has_arch_timer = false;
  83#endif
  84
  85        if (!has_arch_timer || !IS_ENABLED(CONFIG_ARM_ARCH_TIMER)) {
  86                if (is_a7_a8_a9)
  87                        shmobile_setup_delay_hz(max_freq, 1, 3);
  88                else if (is_a15)
  89                        shmobile_setup_delay_hz(max_freq, 2, 4);
  90        }
  91}
  92
  93static void __init shmobile_late_time_init(void)
  94{
  95        /*
  96         * Make sure all compiled-in early timers register themselves.
  97         *
  98         * Run probe() for two "earlytimer" devices, these will be the
  99         * clockevents and clocksource devices respectively. In the event
 100         * that only a clockevents device is available, we -ENODEV on the
 101         * clocksource and the jiffies clocksource is used transparently
 102         * instead. No error handling is necessary here.
 103         */
 104        early_platform_driver_register_all("earlytimer");
 105        early_platform_driver_probe("earlytimer", 2, 0);
 106}
 107
 108void __init shmobile_earlytimer_init(void)
 109{
 110        late_time_init = shmobile_late_time_init;
 111}
 112
 113