drivers/clocksource/timer-goldfish.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include <linux/interrupt.h>
   4 #include <linux/ioport.h>
   5 #include <linux/clocksource.h>
   6 #include <linux/clockchips.h>
   7 #include <linux/module.h>
   8 #include <linux/slab.h>
   9 #include <linux/goldfish.h>
  10 #include <clocksource/timer-goldfish.h>
  11
  12 struct goldfish_timer {
  13         struct clocksource cs;
  14         struct clock_event_device ced;
  15         struct resource res;
  16         void __iomem *base;
  17 };
  18
  19 static struct goldfish_timer *ced_to_gf(struct clock_event_device *ced)
  20 {
  21         return container_of(ced, struct goldfish_timer, ced);
  22 }
  23
  24 static struct goldfish_timer *cs_to_gf(struct clocksource *cs)
  25 {
  26         return container_of(cs, struct goldfish_timer, cs);
  27 }
  28
  29 static u64 goldfish_timer_read(struct clocksource *cs)
  30 {
  31         struct goldfish_timer *timerdrv = cs_to_gf(cs);
  32         void __iomem *base = timerdrv->base;
  33         u32 time_low, time_high;
  34         u64 ticks;
  35
  36         /*
  37          * time_low: get low bits of current time and update time_high
  38          * time_high: get high bits of time at last time_low read
  39          */
  40         time_low = gf_ioread32(base + TIMER_TIME_LOW);
  41         time_high = gf_ioread32(base + TIMER_TIME_HIGH);
  42
  43         ticks = ((u64)time_high << 32) | time_low;
  44
  45         return ticks;
  46 }
  47
  48 static int goldfish_timer_set_oneshot(struct clock_event_device *evt)
  49 {
  50         struct goldfish_timer *timerdrv = ced_to_gf(evt);
  51         void __iomem *base = timerdrv->base;
  52
  53         gf_iowrite32(0, base + TIMER_ALARM_HIGH);
  54         gf_iowrite32(0, base + TIMER_ALARM_LOW);
  55         gf_iowrite32(1, base + TIMER_IRQ_ENABLED);
  56
  57         return 0;
  58 }
  59
  60 static int goldfish_timer_shutdown(struct clock_event_device *evt)
  61 {
  62         struct goldfish_timer *timerdrv = ced_to_gf(evt);
  63         void __iomem *base = timerdrv->base;
  64
  65         gf_iowrite32(0, base + TIMER_IRQ_ENABLED);
  66
  67         return 0;
  68 }
  69
  70 static int goldfish_timer_next_event(unsigned long delta,
  71                                      struct clock_event_device *evt)
  72 {
  73         struct goldfish_timer *timerdrv = ced_to_gf(evt);
  74         void __iomem *base = timerdrv->base;
  75         u64 now;
  76
  77         now = goldfish_timer_read(&timerdrv->cs);
  78
  79         now += delta;
  80
  81         gf_iowrite32(upper_32_bits(now), base + TIMER_ALARM_HIGH);
  82         gf_iowrite32(lower_32_bits(now), base + TIMER_ALARM_LOW);
  83
  84         return 0;
  85 }
  86
  87 static irqreturn_t goldfish_timer_irq(int irq, void *dev_id)
  88 {
  89         struct goldfish_timer *timerdrv = dev_id;
  90         struct clock_event_device *evt = &timerdrv->ced;
  91         void __iomem *base = timerdrv->base;
  92
  93         gf_iowrite32(1, base + TIMER_CLEAR_INTERRUPT);
  94
  95         evt->event_handler(evt);
  96
  97         return IRQ_HANDLED;
  98 }
  99
 100 int __init goldfish_timer_init(int irq, void __iomem *base)
 101 {
 102         struct goldfish_timer *timerdrv;
 103         int ret;
 104
 105         timerdrv = kzalloc(sizeof(*timerdrv), GFP_KERNEL);
 106         if (!timerdrv)
 107                 return -ENOMEM;
 108
 109         timerdrv->base = base;
 110
 111         timerdrv->ced = (struct clock_event_device){
 112                 .name                   = "goldfish_timer",
 113                 .features               = CLOCK_EVT_FEAT_ONESHOT,
 114                 .set_state_shutdown     = goldfish_timer_shutdown,
 115                 .set_state_oneshot      = goldfish_timer_set_oneshot,
 116                 .set_next_event         = goldfish_timer_next_event,
 117         };
 118
 119         timerdrv->res = (struct resource){
 120                 .name  = "goldfish_timer",
 121                 .start = (unsigned long)base,
 122                 .end   = (unsigned long)base + 0xfff,
 123         };
 124
 125         ret = request_resource(&iomem_resource, &timerdrv->res);
 126         if (ret) {
 127                 pr_err("Cannot allocate '%s' resource\n", timerdrv->res.name);
 128                 return ret;
 129         }
 130
 131         timerdrv->cs = (struct clocksource){
 132                 .name           = "goldfish_timer",
 133                 .rating         = 400,
 134                 .read           = goldfish_timer_read,
 135                 .mask           = CLOCKSOURCE_MASK(64),
 136                 .flags          = 0,
 137                 .max_idle_ns    = LONG_MAX,
 138         };
 139
 140         clocksource_register_hz(&timerdrv->cs, NSEC_PER_SEC);
 141
 142         ret = request_irq(irq, goldfish_timer_irq, IRQF_TIMER,
 143                           "goldfish_timer", timerdrv);
 144         if (ret) {
 145                 pr_err("Couldn't register goldfish-timer interrupt\n");
 146                 return ret;
 147         }
 148
 149         clockevents_config_and_register(&timerdrv->ced, NSEC_PER_SEC,
 150                                         1, 0xffffffff);
 151
 152         return 0;
 153 }