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
  35 static u64 au1x_counter1_read(struct clocksource *cs)
  36 {
  37         return alchemy_rdsys(AU1000_SYS_RTCREAD);
  38 }
  39
  40 static 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
  48 static 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
  60 static 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
  67 static 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
  75 static 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
 134 cntr_err:
 135         return -1;
 136 }
 137
 138 static 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
 147 void __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 }