LXR linux/arch/mips/alchemy/common/time.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright (C) 2008-2009 Manuel Lauss <manuel.lauss@gmail.com>
   4 *
   5 * Previous incarnations were:
   6 * Copyright (C) 2001, 2006, 2008 MontaVista Software, <source@mvista.com>
   7 * Copied and modified Carsten Langgaard's time.c
   8 *
   9 * Carsten Langgaard, carstenl@mips.com
  10 * Copyright (C) 1999,2000 MIPS Technologies, Inc.  All rights reserved.
  11 *
  12 * ########################################################################
  13 *
  14 * ########################################################################
  15 *
  16 * Clocksource/event using the 32.768kHz-clocked Counter1 ('RTC' in the
  17 * databooks).  Firmware/Board init code must enable the counters in the
  18 * counter control register, otherwise the CP0 counter clocksource/event
  19 * will be installed instead (and use of 'wait' instruction is prohibited).
  20 */
  21
  22#include <linux/clockchips.h>
  23#include <linux/clocksource.h>
  24#include <linux/interrupt.h>
  25#include <linux/spinlock.h>
  26
  27#include <asm/idle.h>
  28#include <asm/processor.h>
  29#include <asm/time.h>
  30#include <asm/mach-au1x00/au1000.h>
  31
  32/* 32kHz clock enabled and detected */
  33#define CNTR_OK (SYS_CNTRL_E0 | SYS_CNTRL_32S)
  34
  35static u64 au1x_counter1_read(struct clocksource *cs)
  36{
  37        return alchemy_rdsys(AU1000_SYS_RTCREAD);
  38}
  39
  40static struct clocksource au1x_counter1_clocksource = {
  41        .name           = "alchemy-counter1",
  42        .read           = au1x_counter1_read,
  43        .mask           = CLOCKSOURCE_MASK(32),
  44        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  45        .rating         = 1500,
  46};
  47
  48static int au1x_rtcmatch2_set_next_event(unsigned long delta,
  49                                         struct clock_event_device *cd)
  50{
  51        delta += alchemy_rdsys(AU1000_SYS_RTCREAD);
  52        /* wait for register access */
  53        while (alchemy_rdsys(AU1000_SYS_CNTRCTRL) & SYS_CNTRL_M21)
  54                ;
  55        alchemy_wrsys(delta, AU1000_SYS_RTCMATCH2);
  56
  57        return 0;
  58}
  59
  60static irqreturn_t au1x_rtcmatch2_irq(int irq, void *dev_id)
  61{
  62        struct clock_event_device *cd = dev_id;
  63        cd->event_handler(cd);
  64        return IRQ_HANDLED;
  65}
  66
  67static struct clock_event_device au1x_rtcmatch2_clockdev = {
  68        .name           = "rtcmatch2",
  69        .features       = CLOCK_EVT_FEAT_ONESHOT,
  70        .rating         = 1500,
  71        .set_next_event = au1x_rtcmatch2_set_next_event,
  72        .cpumask        = cpu_possible_mask,
  73};
  74
  75static int __init alchemy_time_init(unsigned int m2int)
  76{
  77        struct clock_event_device *cd = &au1x_rtcmatch2_clockdev;
  78        unsigned long t;
  79
  80        au1x_rtcmatch2_clockdev.irq = m2int;
  81
  82        /* Check if firmware (YAMON, ...) has enabled 32kHz and clock
  83         * has been detected.  If so install the rtcmatch2 clocksource,
  84         * otherwise don't bother.  Note that both bits being set is by
  85         * no means a definite guarantee that the counters actually work
  86         * (the 32S bit seems to be stuck set to 1 once a single clock-
  87         * edge is detected, hence the timeouts).
  88         */
  89        if (CNTR_OK != (alchemy_rdsys(AU1000_SYS_CNTRCTRL) & CNTR_OK))
  90                goto cntr_err;
  91
  92        /*
  93         * setup counter 1 (RTC) to tick at full speed
  94         */
  95        t = 0xffffff;
  96        while ((alchemy_rdsys(AU1000_SYS_CNTRCTRL) & SYS_CNTRL_T1S) && --t)
  97                asm volatile ("nop");
  98        if (!t)
  99                goto cntr_err;
 100
 101        alchemy_wrsys(0, AU1000_SYS_RTCTRIM);   /* 32.768 kHz */
 102
 103        t = 0xffffff;
 104        while ((alchemy_rdsys(AU1000_SYS_CNTRCTRL) & SYS_CNTRL_C1S) && --t)
 105                asm volatile ("nop");
 106        if (!t)
 107                goto cntr_err;
 108        alchemy_wrsys(0, AU1000_SYS_RTCWRITE);
 109
 110        t = 0xffffff;
 111        while ((alchemy_rdsys(AU1000_SYS_CNTRCTRL) & SYS_CNTRL_C1S) && --t)
 112                asm volatile ("nop");
 113        if (!t)
 114                goto cntr_err;
 115
 116        /* register counter1 clocksource and event device */
 117        clocksource_register_hz(&au1x_counter1_clocksource, 32768);
 118
 119        cd->shift = 32;
 120        cd->mult = div_sc(32768, NSEC_PER_SEC, cd->shift);
 121        cd->max_delta_ns = clockevent_delta2ns(0xffffffff, cd);
 122        cd->max_delta_ticks = 0xffffffff;
 123        cd->min_delta_ns = clockevent_delta2ns(9, cd);
 124        cd->min_delta_ticks = 9;        /* ~0.28ms */
 125        clockevents_register_device(cd);
 126        if (request_irq(m2int, au1x_rtcmatch2_irq, IRQF_TIMER, "timer",
 127                        &au1x_rtcmatch2_clockdev))
 128                pr_err("Failed to register timer interrupt\n");
 129
 130        printk(KERN_INFO "Alchemy clocksource installed\n");
 131
 132        return 0;
 133
 134cntr_err:
 135        return -1;
 136}
 137
 138static int alchemy_m2inttab[] __initdata = {
 139        AU1000_RTC_MATCH2_INT,
 140        AU1500_RTC_MATCH2_INT,
 141        AU1100_RTC_MATCH2_INT,
 142        AU1550_RTC_MATCH2_INT,
 143        AU1200_RTC_MATCH2_INT,
 144        AU1300_RTC_MATCH2_INT,
 145};
 146
 147void __init plat_time_init(void)
 148{
 149        int t;
 150
 151        t = alchemy_get_cputype();
 152        if (t == ALCHEMY_CPU_UNKNOWN ||
 153            alchemy_time_init(alchemy_m2inttab[t]))
 154                cpu_wait = NULL;        /* wait doesn't work with r4k timer */
 155}
 156