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/notifier.h>
  14 #include <linux/of_irq.h>
  15 #include <linux/percpu.h>
  16 #include <linux/smp.h>
  17 #include <linux/time.h>
  18 #include <asm/mips-cps.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 u64 notrace gic_read_count(void)
  25 {
  26         unsigned int hi, hi2, lo;
  27
  28         if (mips_cm_is64)
  29                 return read_gic_counter();
  30
  31         do {
  32                 hi = read_gic_counter_32h();
  33                 lo = read_gic_counter_32l();
  34                 hi2 = read_gic_counter_32h();
  35         } while (hi2 != hi);
  36
  37         return (((u64) hi) << 32) + lo;
  38 }
  39
  40 static int gic_next_event(unsigned long delta, struct clock_event_device *evt)
  41 {
  42         int cpu = cpumask_first(evt->cpumask);
  43         u64 cnt;
  44         int res;
  45
  46         cnt = gic_read_count();
  47         cnt += (u64)delta;
  48         if (cpu == raw_smp_processor_id()) {
  49                 write_gic_vl_compare(cnt);
  50         } else {
  51                 write_gic_vl_other(mips_cm_vp_id(cpu));
  52                 write_gic_vo_compare(cnt);
  53         }
  54         res = ((int)(gic_read_count() - cnt) >= 0) ? -ETIME : 0;
  55         return res;
  56 }
  57
  58 static irqreturn_t gic_compare_interrupt(int irq, void *dev_id)
  59 {
  60         struct clock_event_device *cd = dev_id;
  61
  62         write_gic_vl_compare(read_gic_vl_compare());
  63         cd->event_handler(cd);
  64         return IRQ_HANDLED;
  65 }
  66
  67 struct irqaction gic_compare_irqaction = {
  68         .handler = gic_compare_interrupt,
  69         .percpu_dev_id = &gic_clockevent_device,
  70         .flags = IRQF_PERCPU | IRQF_TIMER,
  71         .name = "timer",
  72 };
  73
  74 static void gic_clockevent_cpu_init(unsigned int cpu,
  75                                     struct clock_event_device *cd)
  76 {
  77         cd->name                = "MIPS GIC";
  78         cd->features            = CLOCK_EVT_FEAT_ONESHOT |
  79                                   CLOCK_EVT_FEAT_C3STOP;
  80
  81         cd->rating              = 350;
  82         cd->irq                 = gic_timer_irq;
  83         cd->cpumask             = cpumask_of(cpu);
  84         cd->set_next_event      = gic_next_event;
  85
  86         clockevents_config_and_register(cd, gic_frequency, 0x300, 0x7fffffff);
  87
  88         enable_percpu_irq(gic_timer_irq, IRQ_TYPE_NONE);
  89 }
  90
  91 static void gic_clockevent_cpu_exit(struct clock_event_device *cd)
  92 {
  93         disable_percpu_irq(gic_timer_irq);
  94 }
  95
  96 static void gic_update_frequency(void *data)
  97 {
  98         unsigned long rate = (unsigned long)data;
  99
 100         clockevents_update_freq(this_cpu_ptr(&gic_clockevent_device), rate);
 101 }
 102
 103 static int gic_starting_cpu(unsigned int cpu)
 104 {
 105         gic_clockevent_cpu_init(cpu, this_cpu_ptr(&gic_clockevent_device));
 106         return 0;
 107 }
 108
 109 static int gic_clk_notifier(struct notifier_block *nb, unsigned long action,
 110                             void *data)
 111 {
 112         struct clk_notifier_data *cnd = data;
 113
 114         if (action == POST_RATE_CHANGE)
 115                 on_each_cpu(gic_update_frequency, (void *)cnd->new_rate, 1);
 116
 117         return NOTIFY_OK;
 118 }
 119
 120 static int gic_dying_cpu(unsigned int cpu)
 121 {
 122         gic_clockevent_cpu_exit(this_cpu_ptr(&gic_clockevent_device));
 123         return 0;
 124 }
 125
 126 static struct notifier_block gic_clk_nb = {
 127         .notifier_call = gic_clk_notifier,
 128 };
 129
 130 static int gic_clockevent_init(void)
 131 {
 132         int ret;
 133
 134         if (!gic_frequency)
 135                 return -ENXIO;
 136
 137         ret = setup_percpu_irq(gic_timer_irq, &gic_compare_irqaction);
 138         if (ret < 0) {
 139                 pr_err("GIC timer IRQ %d setup failed: %d\n",
 140                        gic_timer_irq, ret);
 141                 return ret;
 142         }
 143
 144         cpuhp_setup_state(CPUHP_AP_MIPS_GIC_TIMER_STARTING,
 145                           "clockevents/mips/gic/timer:starting",
 146                           gic_starting_cpu, gic_dying_cpu);
 147         return 0;
 148 }
 149
 150 static u64 gic_hpt_read(struct clocksource *cs)
 151 {
 152         return gic_read_count();
 153 }
 154
 155 static struct clocksource gic_clocksource = {
 156         .name           = "GIC",
 157         .read           = gic_hpt_read,
 158         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 159         .archdata       = { .vdso_clock_mode = VDSO_CLOCK_GIC },
 160 };
 161
 162 static int __init __gic_clocksource_init(void)
 163 {
 164         unsigned int count_width;
 165         int ret;
 166
 167         /* Set clocksource mask. */
 168         count_width = read_gic_config() & GIC_CONFIG_COUNTBITS;
 169         count_width >>= __fls(GIC_CONFIG_COUNTBITS);
 170         count_width *= 4;
 171         count_width += 32;
 172         gic_clocksource.mask = CLOCKSOURCE_MASK(count_width);
 173
 174         /* Calculate a somewhat reasonable rating value. */
 175         gic_clocksource.rating = 200 + gic_frequency / 10000000;
 176
 177         ret = clocksource_register_hz(&gic_clocksource, gic_frequency);
 178         if (ret < 0)
 179                 pr_warn("GIC: Unable to register clocksource\n");
 180
 181         return ret;
 182 }
 183
 184 static int __init gic_clocksource_of_init(struct device_node *node)
 185 {
 186         struct clk *clk;
 187         int ret;
 188
 189         if (!mips_gic_present() || !node->parent ||
 190             !of_device_is_compatible(node->parent, "mti,gic")) {
 191                 pr_warn("No DT definition for the mips gic driver\n");
 192                 return -ENXIO;
 193         }
 194
 195         clk = of_clk_get(node, 0);
 196         if (!IS_ERR(clk)) {
 197                 ret = clk_prepare_enable(clk);
 198                 if (ret < 0) {
 199                         pr_err("GIC failed to enable clock\n");
 200                         clk_put(clk);
 201                         return ret;
 202                 }
 203
 204                 gic_frequency = clk_get_rate(clk);
 205         } else if (of_property_read_u32(node, "clock-frequency",
 206                                         &gic_frequency)) {
 207                 pr_err("GIC frequency not specified.\n");
 208                 return -EINVAL;;
 209         }
 210         gic_timer_irq = irq_of_parse_and_map(node, 0);
 211         if (!gic_timer_irq) {
 212                 pr_err("GIC timer IRQ not specified.\n");
 213                 return -EINVAL;;
 214         }
 215
 216         ret = __gic_clocksource_init();
 217         if (ret)
 218                 return ret;
 219
 220         ret = gic_clockevent_init();
 221         if (!ret && !IS_ERR(clk)) {
 222                 if (clk_notifier_register(clk, &gic_clk_nb) < 0)
 223                         pr_warn("GIC: Unable to register clock notifier\n");
 224         }
 225
 226         /* And finally start the counter */
 227         clear_gic_config(GIC_CONFIG_COUNTSTOP);
 228
 229         return 0;
 230 }
 231 TIMER_OF_DECLARE(mips_gic_timer, "mti,gic-timer",
 232                        gic_clocksource_of_init);