arch/hexagon/kernel/time.c

   1 /*
   2  * Time related functions for Hexagon architecture
   3  *
   4  * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 and
   8  * only version 2 as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18  * 02110-1301, USA.
  19  */
  20
  21 #include <linux/init.h>
  22 #include <linux/clockchips.h>
  23 #include <linux/clocksource.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/err.h>
  26 #include <linux/platform_device.h>
  27 #include <linux/ioport.h>
  28 #include <linux/of.h>
  29 #include <linux/of_address.h>
  30 #include <linux/of_irq.h>
  31 #include <linux/module.h>
  32
  33 #include <asm/timer-regs.h>
  34 #include <asm/hexagon_vm.h>
  35
  36 /*
  37  * For the clocksource we need:
  38  *      pcycle frequency (600MHz)
  39  * For the loops_per_jiffy we need:
  40  *      thread/cpu frequency (100MHz)
  41  * And for the timer, we need:
  42  *      sleep clock rate
  43  */
  44
  45 cycles_t        pcycle_freq_mhz;
  46 cycles_t        thread_freq_mhz;
  47 cycles_t        sleep_clk_freq;
  48
  49 static struct resource rtos_timer_resources[] = {
  50         {
  51                 .start  = RTOS_TIMER_REGS_ADDR,
  52                 .end    = RTOS_TIMER_REGS_ADDR+PAGE_SIZE-1,
  53                 .flags  = IORESOURCE_MEM,
  54         },
  55 };
  56
  57 static struct platform_device rtos_timer_device = {
  58         .name           = "rtos_timer",
  59         .id             = -1,
  60         .num_resources  = ARRAY_SIZE(rtos_timer_resources),
  61         .resource       = rtos_timer_resources,
  62 };
  63
  64 /*  A lot of this stuff should move into a platform specific section.  */
  65 struct adsp_hw_timer_struct {
  66         u32 match;   /*  Match value  */
  67         u32 count;
  68         u32 enable;  /*  [1] - CLR_ON_MATCH_EN, [0] - EN  */
  69         u32 clear;   /*  one-shot register that clears the count  */
  70 };
  71
  72 /*  Look for "TCX0" for related constants.  */
  73 static __iomem struct adsp_hw_timer_struct *rtos_timer;
  74
  75 static cycle_t timer_get_cycles(struct clocksource *cs)
  76 {
  77         return (cycle_t) __vmgettime();
  78 }
  79
  80 static struct clocksource hexagon_clocksource = {
  81         .name           = "pcycles",
  82         .rating         = 250,
  83         .read           = timer_get_cycles,
  84         .mask           = CLOCKSOURCE_MASK(64),
  85         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  86 };
  87
  88 static int set_next_event(unsigned long delta, struct clock_event_device *evt)
  89 {
  90         /*  Assuming the timer will be disabled when we enter here.  */
  91
  92         iowrite32(1, &rtos_timer->clear);
  93         iowrite32(0, &rtos_timer->clear);
  94
  95         iowrite32(delta, &rtos_timer->match);
  96         iowrite32(1 << TIMER_ENABLE, &rtos_timer->enable);
  97         return 0;
  98 }
  99
 100 /*
 101  * Sets the mode (periodic, shutdown, oneshot, etc) of a timer.
 102  */
 103 static void set_mode(enum clock_event_mode mode,
 104         struct clock_event_device *evt)
 105 {
 106         switch (mode) {
 107         case CLOCK_EVT_MODE_SHUTDOWN:
 108                 /* XXX implement me */
 109         default:
 110                 break;
 111         }
 112 }
 113
 114 #ifdef CONFIG_SMP
 115 /*  Broadcast mechanism  */
 116 static void broadcast(const struct cpumask *mask)
 117 {
 118         send_ipi(mask, IPI_TIMER);
 119 }
 120 #endif
 121
 122 static struct clock_event_device hexagon_clockevent_dev = {
 123         .name           = "clockevent",
 124         .features       = CLOCK_EVT_FEAT_ONESHOT,
 125         .rating         = 400,
 126         .irq            = RTOS_TIMER_INT,
 127         .set_next_event = set_next_event,
 128         .set_mode       = set_mode,
 129 #ifdef CONFIG_SMP
 130         .broadcast      = broadcast,
 131 #endif
 132 };
 133
 134 #ifdef CONFIG_SMP
 135 static DEFINE_PER_CPU(struct clock_event_device, clock_events);
 136
 137 void setup_percpu_clockdev(void)
 138 {
 139         int cpu = smp_processor_id();
 140         struct clock_event_device *ce_dev = &hexagon_clockevent_dev;
 141         struct clock_event_device *dummy_clock_dev =
 142                 &per_cpu(clock_events, cpu);
 143
 144         memcpy(dummy_clock_dev, ce_dev, sizeof(*dummy_clock_dev));
 145         INIT_LIST_HEAD(&dummy_clock_dev->list);
 146
 147         dummy_clock_dev->features = CLOCK_EVT_FEAT_DUMMY;
 148         dummy_clock_dev->cpumask = cpumask_of(cpu);
 149         dummy_clock_dev->mode = CLOCK_EVT_MODE_UNUSED;
 150
 151         clockevents_register_device(dummy_clock_dev);
 152 }
 153
 154 /*  Called from smp.c for each CPU's timer ipi call  */
 155 void ipi_timer(void)
 156 {
 157         int cpu = smp_processor_id();
 158         struct clock_event_device *ce_dev = &per_cpu(clock_events, cpu);
 159
 160         ce_dev->event_handler(ce_dev);
 161 }
 162 #endif /* CONFIG_SMP */
 163
 164 static irqreturn_t timer_interrupt(int irq, void *devid)
 165 {
 166         struct clock_event_device *ce_dev = &hexagon_clockevent_dev;
 167
 168         iowrite32(0, &rtos_timer->enable);
 169         ce_dev->event_handler(ce_dev);
 170
 171         return IRQ_HANDLED;
 172 }
 173
 174 /*  This should also be pulled from devtree  */
 175 static struct irqaction rtos_timer_intdesc = {
 176         .handler = timer_interrupt,
 177         .flags = IRQF_TIMER | IRQF_TRIGGER_RISING,
 178         .name = "rtos_timer"
 179 };
 180
 181 /*
 182  * time_init_deferred - called by start_kernel to set up timer/clock source
 183  *
 184  * Install the IRQ handler for the clock, setup timers.
 185  * This is done late, as that way, we can use ioremap().
 186  *
 187  * This runs just before the delay loop is calibrated, and
 188  * is used for delay calibration.
 189  */
 190 void __init time_init_deferred(void)
 191 {
 192         struct resource *resource = NULL;
 193         struct clock_event_device *ce_dev = &hexagon_clockevent_dev;
 194         struct device_node *dn;
 195         struct resource r;
 196         int err;
 197
 198         ce_dev->cpumask = cpu_all_mask;
 199
 200         if (!resource)
 201                 resource = rtos_timer_device.resource;
 202
 203         /*  ioremap here means this has to run later, after paging init  */
 204         rtos_timer = ioremap(resource->start, resource_size(resource));
 205
 206         if (!rtos_timer) {
 207                 release_mem_region(resource->start, resource_size(resource));
 208         }
 209         clocksource_register_khz(&hexagon_clocksource, pcycle_freq_mhz * 1000);
 210
 211         /*  Note: the sim generic RTOS clock is apparently really 18750Hz  */
 212
 213         /*
 214          * Last arg is some guaranteed seconds for which the conversion will
 215          * work without overflow.
 216          */
 217         clockevents_calc_mult_shift(ce_dev, sleep_clk_freq, 4);
 218
 219         ce_dev->max_delta_ns = clockevent_delta2ns(0x7fffffff, ce_dev);
 220         ce_dev->min_delta_ns = clockevent_delta2ns(0xf, ce_dev);
 221
 222 #ifdef CONFIG_SMP
 223         setup_percpu_clockdev();
 224 #endif
 225
 226         clockevents_register_device(ce_dev);
 227         setup_irq(ce_dev->irq, &rtos_timer_intdesc);
 228 }
 229
 230 void __init time_init(void)
 231 {
 232         late_time_init = time_init_deferred;
 233 }
 234
 235 /*
 236  * This could become parametric or perhaps even computed at run-time,
 237  * but for now we take the observed simulator jitter.
 238  */
 239 static long long fudgefactor = 350;  /* Maybe lower if kernel optimized. */
 240
 241 void __udelay(unsigned long usecs)
 242 {
 243         unsigned long long start = __vmgettime();
 244         unsigned long long finish = (pcycle_freq_mhz * usecs) - fudgefactor;
 245
 246         while ((__vmgettime() - start) < finish)
 247                 cpu_relax(); /*  not sure how this improves readability  */
 248 }
 249 EXPORT_SYMBOL(__udelay);