root/arch/hexagon/kernel/time.c

DEFINITIONS

1. timer_get_cycles
2. set_next_event
3. broadcast
4. setup_percpu_clockdev
5. ipi_timer
6. timer_interrupt
7. time_init_deferred
8. time_init
9. __delay
10. __udelay

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Time related functions for Hexagon architecture
   4  *
   5  * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
   6  */
   7 
   8 #include <linux/init.h>
   9 #include <linux/clockchips.h>
  10 #include <linux/clocksource.h>
  11 #include <linux/interrupt.h>
  12 #include <linux/err.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/ioport.h>
  15 #include <linux/of.h>
  16 #include <linux/of_address.h>
  17 #include <linux/of_irq.h>
  18 #include <linux/module.h>
  19 
  20 #include <asm/timer-regs.h>
  21 #include <asm/hexagon_vm.h>
  22 
  23 /*
  24  * For the clocksource we need:
  25  *      pcycle frequency (600MHz)
  26  * For the loops_per_jiffy we need:
  27  *      thread/cpu frequency (100MHz)
  28  * And for the timer, we need:
  29  *      sleep clock rate
  30  */
  31 
  32 cycles_t        pcycle_freq_mhz;
  33 cycles_t        thread_freq_mhz;
  34 cycles_t        sleep_clk_freq;
  35 
  36 static struct resource rtos_timer_resources[] = {
  37         {
  38                 .start  = RTOS_TIMER_REGS_ADDR,
  39                 .end    = RTOS_TIMER_REGS_ADDR+PAGE_SIZE-1,
  40                 .flags  = IORESOURCE_MEM,
  41         },
  42 };
  43 
  44 static struct platform_device rtos_timer_device = {
  45         .name           = "rtos_timer",
  46         .id             = -1,
  47         .num_resources  = ARRAY_SIZE(rtos_timer_resources),
  48         .resource       = rtos_timer_resources,
  49 };
  50 
  51 /*  A lot of this stuff should move into a platform specific section.  */
  52 struct adsp_hw_timer_struct {
  53         u32 match;   /*  Match value  */
  54         u32 count;
  55         u32 enable;  /*  [1] - CLR_ON_MATCH_EN, [0] - EN  */
  56         u32 clear;   /*  one-shot register that clears the count  */
  57 };
  58 
  59 /*  Look for "TCX0" for related constants.  */
  60 static __iomem struct adsp_hw_timer_struct *rtos_timer;
  61 
  62 static u64 timer_get_cycles(struct clocksource *cs)
  63 {
  64         return (u64) __vmgettime();
  65 }
  66 
  67 static struct clocksource hexagon_clocksource = {
  68         .name           = "pcycles",
  69         .rating         = 250,
  70         .read           = timer_get_cycles,
  71         .mask           = CLOCKSOURCE_MASK(64),
  72         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  73 };
  74 
  75 static int set_next_event(unsigned long delta, struct clock_event_device *evt)
  76 {
  77         /*  Assuming the timer will be disabled when we enter here.  */
  78 
  79         iowrite32(1, &rtos_timer->clear);
  80         iowrite32(0, &rtos_timer->clear);
  81 
  82         iowrite32(delta, &rtos_timer->match);
  83         iowrite32(1 << TIMER_ENABLE, &rtos_timer->enable);
  84         return 0;
  85 }
  86 
  87 #ifdef CONFIG_SMP
  88 /*  Broadcast mechanism  */
  89 static void broadcast(const struct cpumask *mask)
  90 {
  91         send_ipi(mask, IPI_TIMER);
  92 }
  93 #endif
  94 
  95 /* XXX Implement set_state_shutdown() */
  96 static struct clock_event_device hexagon_clockevent_dev = {
  97         .name           = "clockevent",
  98         .features       = CLOCK_EVT_FEAT_ONESHOT,
  99         .rating         = 400,
 100         .irq            = RTOS_TIMER_INT,
 101         .set_next_event = set_next_event,
 102 #ifdef CONFIG_SMP
 103         .broadcast      = broadcast,
 104 #endif
 105 };
 106 
 107 #ifdef CONFIG_SMP
 108 static DEFINE_PER_CPU(struct clock_event_device, clock_events);
 109 
 110 void setup_percpu_clockdev(void)
 111 {
 112         int cpu = smp_processor_id();
 113         struct clock_event_device *ce_dev = &hexagon_clockevent_dev;
 114         struct clock_event_device *dummy_clock_dev =
 115                 &per_cpu(clock_events, cpu);
 116 
 117         memcpy(dummy_clock_dev, ce_dev, sizeof(*dummy_clock_dev));
 118         INIT_LIST_HEAD(&dummy_clock_dev->list);
 119 
 120         dummy_clock_dev->features = CLOCK_EVT_FEAT_DUMMY;
 121         dummy_clock_dev->cpumask = cpumask_of(cpu);
 122 
 123         clockevents_register_device(dummy_clock_dev);
 124 }
 125 
 126 /*  Called from smp.c for each CPU's timer ipi call  */
 127 void ipi_timer(void)
 128 {
 129         int cpu = smp_processor_id();
 130         struct clock_event_device *ce_dev = &per_cpu(clock_events, cpu);
 131 
 132         ce_dev->event_handler(ce_dev);
 133 }
 134 #endif /* CONFIG_SMP */
 135 
 136 static irqreturn_t timer_interrupt(int irq, void *devid)
 137 {
 138         struct clock_event_device *ce_dev = &hexagon_clockevent_dev;
 139 
 140         iowrite32(0, &rtos_timer->enable);
 141         ce_dev->event_handler(ce_dev);
 142 
 143         return IRQ_HANDLED;
 144 }
 145 
 146 /*  This should also be pulled from devtree  */
 147 static struct irqaction rtos_timer_intdesc = {
 148         .handler = timer_interrupt,
 149         .flags = IRQF_TIMER | IRQF_TRIGGER_RISING,
 150         .name = "rtos_timer"
 151 };
 152 
 153 /*
 154  * time_init_deferred - called by start_kernel to set up timer/clock source
 155  *
 156  * Install the IRQ handler for the clock, setup timers.
 157  * This is done late, as that way, we can use ioremap().
 158  *
 159  * This runs just before the delay loop is calibrated, and
 160  * is used for delay calibration.
 161  */
 162 void __init time_init_deferred(void)
 163 {
 164         struct resource *resource = NULL;
 165         struct clock_event_device *ce_dev = &hexagon_clockevent_dev;
 166 
 167         ce_dev->cpumask = cpu_all_mask;
 168 
 169         if (!resource)
 170                 resource = rtos_timer_device.resource;
 171 
 172         /*  ioremap here means this has to run later, after paging init  */
 173         rtos_timer = ioremap(resource->start, resource_size(resource));
 174 
 175         if (!rtos_timer) {
 176                 release_mem_region(resource->start, resource_size(resource));
 177         }
 178         clocksource_register_khz(&hexagon_clocksource, pcycle_freq_mhz * 1000);
 179 
 180         /*  Note: the sim generic RTOS clock is apparently really 18750Hz  */
 181 
 182         /*
 183          * Last arg is some guaranteed seconds for which the conversion will
 184          * work without overflow.
 185          */
 186         clockevents_calc_mult_shift(ce_dev, sleep_clk_freq, 4);
 187 
 188         ce_dev->max_delta_ns = clockevent_delta2ns(0x7fffffff, ce_dev);
 189         ce_dev->max_delta_ticks = 0x7fffffff;
 190         ce_dev->min_delta_ns = clockevent_delta2ns(0xf, ce_dev);
 191         ce_dev->min_delta_ticks = 0xf;
 192 
 193 #ifdef CONFIG_SMP
 194         setup_percpu_clockdev();
 195 #endif
 196 
 197         clockevents_register_device(ce_dev);
 198         setup_irq(ce_dev->irq, &rtos_timer_intdesc);
 199 }
 200 
 201 void __init time_init(void)
 202 {
 203         late_time_init = time_init_deferred;
 204 }
 205 
 206 void __delay(unsigned long cycles)
 207 {
 208         unsigned long long start = __vmgettime();
 209 
 210         while ((__vmgettime() - start) < cycles)
 211                 cpu_relax();
 212 }
 213 EXPORT_SYMBOL(__delay);
 214 
 215 /*
 216  * This could become parametric or perhaps even computed at run-time,
 217  * but for now we take the observed simulator jitter.
 218  */
 219 static long long fudgefactor = 350;  /* Maybe lower if kernel optimized. */
 220 
 221 void __udelay(unsigned long usecs)
 222 {
 223         unsigned long long start = __vmgettime();
 224         unsigned long long finish = (pcycle_freq_mhz * usecs) - fudgefactor;
 225 
 226         while ((__vmgettime() - start) < finish)
 227                 cpu_relax(); /*  not sure how this improves readability  */
 228 }
 229 EXPORT_SYMBOL(__udelay);