drivers/clocksource/mips-gic-timer.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 2012 MIPS Technologies, Inc.  All rights reserved.
   7  */
   8 #include <linux/clk.h>
   9 #include <linux/clockchips.h>
  10 #include <linux/cpu.h>
  11 #include <linux/init.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/irqchip/mips-gic.h>
  14 #include <linux/notifier.h>
  15 #include <linux/of_irq.h>
  16 #include <linux/percpu.h>
  17 #include <linux/smp.h>
  18 #include <linux/time.h>
  19
  20 static DEFINE_PER_CPU(struct clock_event_device, gic_clockevent_device);
  21 static int gic_timer_irq;
  22 static unsigned int gic_frequency;
  23
  24 static int gic_next_event(unsigned long delta, struct clock_event_device *evt)
  25 {
  26         u64 cnt;
  27         int res;
  28
  29         cnt = gic_read_count();
  30         cnt += (u64)delta;
  31         gic_write_cpu_compare(cnt, cpumask_first(evt->cpumask));
  32         res = ((int)(gic_read_count() - cnt) >= 0) ? -ETIME : 0;
  33         return res;
  34 }
  35
  36 static irqreturn_t gic_compare_interrupt(int irq, void *dev_id)
  37 {
  38         struct clock_event_device *cd = dev_id;
  39
  40         gic_write_compare(gic_read_compare());
  41         cd->event_handler(cd);
  42         return IRQ_HANDLED;
  43 }
  44
  45 struct irqaction gic_compare_irqaction = {
  46         .handler = gic_compare_interrupt,
  47         .percpu_dev_id = &gic_clockevent_device,
  48         .flags = IRQF_PERCPU | IRQF_TIMER,
  49         .name = "timer",
  50 };
  51
  52 static void gic_clockevent_cpu_init(unsigned int cpu,
  53                                     struct clock_event_device *cd)
  54 {
  55         cd->name                = "MIPS GIC";
  56         cd->features            = CLOCK_EVT_FEAT_ONESHOT |
  57                                   CLOCK_EVT_FEAT_C3STOP;
  58
  59         cd->rating              = 350;
  60         cd->irq                 = gic_timer_irq;
  61         cd->cpumask             = cpumask_of(cpu);
  62         cd->set_next_event      = gic_next_event;
  63
  64         clockevents_config_and_register(cd, gic_frequency, 0x300, 0x7fffffff);
  65
  66         enable_percpu_irq(gic_timer_irq, IRQ_TYPE_NONE);
  67 }
  68
  69 static void gic_clockevent_cpu_exit(struct clock_event_device *cd)
  70 {
  71         disable_percpu_irq(gic_timer_irq);
  72 }
  73
  74 static void gic_update_frequency(void *data)
  75 {
  76         unsigned long rate = (unsigned long)data;
  77
  78         clockevents_update_freq(this_cpu_ptr(&gic_clockevent_device), rate);
  79 }
  80
  81 static int gic_starting_cpu(unsigned int cpu)
  82 {
  83         gic_clockevent_cpu_init(cpu, this_cpu_ptr(&gic_clockevent_device));
  84         return 0;
  85 }
  86
  87 static int gic_clk_notifier(struct notifier_block *nb, unsigned long action,
  88                             void *data)
  89 {
  90         struct clk_notifier_data *cnd = data;
  91
  92         if (action == POST_RATE_CHANGE)
  93                 on_each_cpu(gic_update_frequency, (void *)cnd->new_rate, 1);
  94
  95         return NOTIFY_OK;
  96 }
  97
  98 static int gic_dying_cpu(unsigned int cpu)
  99 {
 100         gic_clockevent_cpu_exit(this_cpu_ptr(&gic_clockevent_device));
 101         return 0;
 102 }
 103
 104 static struct notifier_block gic_clk_nb = {
 105         .notifier_call = gic_clk_notifier,
 106 };
 107
 108 static int gic_clockevent_init(void)
 109 {
 110         int ret;
 111
 112         if (!gic_frequency)
 113                 return -ENXIO;
 114
 115         ret = setup_percpu_irq(gic_timer_irq, &gic_compare_irqaction);
 116         if (ret < 0) {
 117                 pr_err("GIC timer IRQ %d setup failed: %d\n",
 118                        gic_timer_irq, ret);
 119                 return ret;
 120         }
 121
 122         cpuhp_setup_state(CPUHP_AP_MIPS_GIC_TIMER_STARTING,
 123                           "clockevents/mips/gic/timer:starting",
 124                           gic_starting_cpu, gic_dying_cpu);
 125         return 0;
 126 }
 127
 128 static u64 gic_hpt_read(struct clocksource *cs)
 129 {
 130         return gic_read_count();
 131 }
 132
 133 static struct clocksource gic_clocksource = {
 134         .name           = "GIC",
 135         .read           = gic_hpt_read,
 136         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 137         .archdata       = { .vdso_clock_mode = VDSO_CLOCK_GIC },
 138 };
 139
 140 static int __init __gic_clocksource_init(void)
 141 {
 142         int ret;
 143
 144         /* Set clocksource mask. */
 145         gic_clocksource.mask = CLOCKSOURCE_MASK(gic_get_count_width());
 146
 147         /* Calculate a somewhat reasonable rating value. */
 148         gic_clocksource.rating = 200 + gic_frequency / 10000000;
 149
 150         ret = clocksource_register_hz(&gic_clocksource, gic_frequency);
 151         if (ret < 0)
 152                 pr_warn("GIC: Unable to register clocksource\n");
 153
 154         return ret;
 155 }
 156
 157 static int __init gic_clocksource_of_init(struct device_node *node)
 158 {
 159         struct clk *clk;
 160         int ret;
 161
 162         if (!gic_present || !node->parent ||
 163             !of_device_is_compatible(node->parent, "mti,gic")) {
 164                 pr_warn("No DT definition for the mips gic driver\n");
 165                 return -ENXIO;
 166         }
 167
 168         clk = of_clk_get(node, 0);
 169         if (!IS_ERR(clk)) {
 170                 ret = clk_prepare_enable(clk);
 171                 if (ret < 0) {
 172                         pr_err("GIC failed to enable clock\n");
 173                         clk_put(clk);
 174                         return ret;
 175                 }
 176
 177                 gic_frequency = clk_get_rate(clk);
 178         } else if (of_property_read_u32(node, "clock-frequency",
 179                                         &gic_frequency)) {
 180                 pr_err("GIC frequency not specified.\n");
 181                 return -EINVAL;;
 182         }
 183         gic_timer_irq = irq_of_parse_and_map(node, 0);
 184         if (!gic_timer_irq) {
 185                 pr_err("GIC timer IRQ not specified.\n");
 186                 return -EINVAL;;
 187         }
 188
 189         ret = __gic_clocksource_init();
 190         if (ret)
 191                 return ret;
 192
 193         ret = gic_clockevent_init();
 194         if (!ret && !IS_ERR(clk)) {
 195                 if (clk_notifier_register(clk, &gic_clk_nb) < 0)
 196                         pr_warn("GIC: Unable to register clock notifier\n");
 197         }
 198
 199         /* And finally start the counter */
 200         gic_start_count();
 201
 202         return 0;
 203 }
 204 TIMER_OF_DECLARE(mips_gic_timer, "mti,gic-timer",
 205                        gic_clocksource_of_init);