linux/arch/mips/mti-malta/malta-time.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Carsten Langgaard, carstenl@mips.com
   4 * Copyright (C) 1999,2000 MIPS Technologies, Inc.  All rights reserved.
   5 *
   6 * Setting up the clock on the MIPS boards.
   7 */
   8#include <linux/types.h>
   9#include <linux/i8253.h>
  10#include <linux/init.h>
  11#include <linux/kernel_stat.h>
  12#include <linux/libfdt.h>
  13#include <linux/math64.h>
  14#include <linux/sched.h>
  15#include <linux/spinlock.h>
  16#include <linux/interrupt.h>
  17#include <linux/timex.h>
  18#include <linux/mc146818rtc.h>
  19
  20#include <asm/cpu.h>
  21#include <asm/mipsregs.h>
  22#include <asm/mipsmtregs.h>
  23#include <asm/hardirq.h>
  24#include <asm/irq.h>
  25#include <asm/div64.h>
  26#include <asm/setup.h>
  27#include <asm/time.h>
  28#include <asm/mc146818-time.h>
  29#include <asm/msc01_ic.h>
  30#include <asm/mips-cps.h>
  31
  32#include <asm/mips-boards/generic.h>
  33#include <asm/mips-boards/maltaint.h>
  34
  35static int mips_cpu_timer_irq;
  36static int mips_cpu_perf_irq;
  37extern int cp0_perfcount_irq;
  38
  39static unsigned int gic_frequency;
  40
  41static void mips_timer_dispatch(void)
  42{
  43        do_IRQ(mips_cpu_timer_irq);
  44}
  45
  46static void mips_perf_dispatch(void)
  47{
  48        do_IRQ(mips_cpu_perf_irq);
  49}
  50
  51static unsigned int freqround(unsigned int freq, unsigned int amount)
  52{
  53        freq += amount;
  54        freq -= freq % (amount*2);
  55        return freq;
  56}
  57
  58/*
  59 * Estimate CPU and GIC frequencies.
  60 */
  61static void __init estimate_frequencies(void)
  62{
  63        unsigned long flags;
  64        unsigned int count, start;
  65        unsigned char secs1, secs2, ctrl;
  66        int secs;
  67        u64 giccount = 0, gicstart = 0;
  68
  69        local_irq_save(flags);
  70
  71        if (mips_gic_present())
  72                clear_gic_config(GIC_CONFIG_COUNTSTOP);
  73
  74        /*
  75         * Read counters exactly on rising edge of update flag.
  76         * This helps get an accurate reading under virtualisation.
  77         */
  78        while (CMOS_READ(RTC_REG_A) & RTC_UIP);
  79        while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));
  80        start = read_c0_count();
  81        if (mips_gic_present())
  82                gicstart = read_gic_counter();
  83
  84        /* Wait for falling edge before reading RTC. */
  85        while (CMOS_READ(RTC_REG_A) & RTC_UIP);
  86        secs1 = CMOS_READ(RTC_SECONDS);
  87
  88        /* Read counters again exactly on rising edge of update flag. */
  89        while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));
  90        count = read_c0_count();
  91        if (mips_gic_present())
  92                giccount = read_gic_counter();
  93
  94        /* Wait for falling edge before reading RTC again. */
  95        while (CMOS_READ(RTC_REG_A) & RTC_UIP);
  96        secs2 = CMOS_READ(RTC_SECONDS);
  97
  98        ctrl = CMOS_READ(RTC_CONTROL);
  99
 100        local_irq_restore(flags);
 101
 102        if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
 103                secs1 = bcd2bin(secs1);
 104                secs2 = bcd2bin(secs2);
 105        }
 106        secs = secs2 - secs1;
 107        if (secs < 1)
 108                secs += 60;
 109
 110        count -= start;
 111        count /= secs;
 112        mips_hpt_frequency = count;
 113
 114        if (mips_gic_present()) {
 115                giccount = div_u64(giccount - gicstart, secs);
 116                gic_frequency = giccount;
 117        }
 118}
 119
 120void read_persistent_clock64(struct timespec64 *ts)
 121{
 122        ts->tv_sec = mc146818_get_cmos_time();
 123        ts->tv_nsec = 0;
 124}
 125
 126int get_c0_fdc_int(void)
 127{
 128        /*
 129         * Some cores claim the FDC is routable through the GIC, but it doesn't
 130         * actually seem to be connected for those Malta bitstreams.
 131         */
 132        switch (current_cpu_type()) {
 133        case CPU_INTERAPTIV:
 134        case CPU_PROAPTIV:
 135                return -1;
 136        }
 137
 138        if (cpu_has_veic)
 139                return -1;
 140        else if (mips_gic_present())
 141                return gic_get_c0_fdc_int();
 142        else if (cp0_fdc_irq >= 0)
 143                return MIPS_CPU_IRQ_BASE + cp0_fdc_irq;
 144        else
 145                return -1;
 146}
 147
 148int get_c0_perfcount_int(void)
 149{
 150        if (cpu_has_veic) {
 151                set_vi_handler(MSC01E_INT_PERFCTR, mips_perf_dispatch);
 152                mips_cpu_perf_irq = MSC01E_INT_BASE + MSC01E_INT_PERFCTR;
 153        } else if (mips_gic_present()) {
 154                mips_cpu_perf_irq = gic_get_c0_perfcount_int();
 155        } else if (cp0_perfcount_irq >= 0) {
 156                mips_cpu_perf_irq = MIPS_CPU_IRQ_BASE + cp0_perfcount_irq;
 157        } else {
 158                mips_cpu_perf_irq = -1;
 159        }
 160
 161        return mips_cpu_perf_irq;
 162}
 163EXPORT_SYMBOL_GPL(get_c0_perfcount_int);
 164
 165unsigned int get_c0_compare_int(void)
 166{
 167        if (cpu_has_veic) {
 168                set_vi_handler(MSC01E_INT_CPUCTR, mips_timer_dispatch);
 169                mips_cpu_timer_irq = MSC01E_INT_BASE + MSC01E_INT_CPUCTR;
 170        } else if (mips_gic_present()) {
 171                mips_cpu_timer_irq = gic_get_c0_compare_int();
 172        } else {
 173                mips_cpu_timer_irq = MIPS_CPU_IRQ_BASE + cp0_compare_irq;
 174        }
 175
 176        return mips_cpu_timer_irq;
 177}
 178
 179static void __init init_rtc(void)
 180{
 181        unsigned char freq, ctrl;
 182
 183        /* Set 32KHz time base if not already set */
 184        freq = CMOS_READ(RTC_FREQ_SELECT);
 185        if ((freq & RTC_DIV_CTL) != RTC_REF_CLCK_32KHZ)
 186                CMOS_WRITE(RTC_REF_CLCK_32KHZ, RTC_FREQ_SELECT);
 187
 188        /* Ensure SET bit is clear so RTC can run */
 189        ctrl = CMOS_READ(RTC_CONTROL);
 190        if (ctrl & RTC_SET)
 191                CMOS_WRITE(ctrl & ~RTC_SET, RTC_CONTROL);
 192}
 193
 194#ifdef CONFIG_CLKSRC_MIPS_GIC
 195static u32 gic_frequency_dt;
 196
 197static struct property gic_frequency_prop = {
 198        .name = "clock-frequency",
 199        .length = sizeof(u32),
 200        .value = &gic_frequency_dt,
 201};
 202
 203static void update_gic_frequency_dt(void)
 204{
 205        struct device_node *node;
 206
 207        gic_frequency_dt = cpu_to_be32(gic_frequency);
 208
 209        node = of_find_compatible_node(NULL, NULL, "mti,gic-timer");
 210        if (!node) {
 211                pr_err("mti,gic-timer device node not found\n");
 212                return;
 213        }
 214
 215        if (of_update_property(node, &gic_frequency_prop) < 0)
 216                pr_err("error updating gic frequency property\n");
 217}
 218
 219#endif
 220
 221void __init plat_time_init(void)
 222{
 223        unsigned int prid = read_c0_prid() & (PRID_COMP_MASK | PRID_IMP_MASK);
 224        unsigned int freq;
 225
 226        init_rtc();
 227        estimate_frequencies();
 228
 229        freq = mips_hpt_frequency;
 230        if ((prid != (PRID_COMP_MIPS | PRID_IMP_20KC)) &&
 231            (prid != (PRID_COMP_MIPS | PRID_IMP_25KF)))
 232                freq *= 2;
 233        freq = freqround(freq, 5000);
 234        printk("CPU frequency %d.%02d MHz\n", freq/1000000,
 235               (freq%1000000)*100/1000000);
 236
 237#ifdef CONFIG_I8253
 238        /* Only Malta has a PIT. */
 239        setup_pit_timer();
 240#endif
 241
 242        if (mips_gic_present()) {
 243                freq = freqround(gic_frequency, 5000);
 244                printk("GIC frequency %d.%02d MHz\n", freq/1000000,
 245                       (freq%1000000)*100/1000000);
 246#ifdef CONFIG_CLKSRC_MIPS_GIC
 247                update_gic_frequency_dt();
 248                timer_probe();
 249#endif
 250        }
 251}
 252