arch/arc/kernel/time.c

   1 /*
   2  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * vineetg: Jan 1011
   9  *  -sched_clock( ) no longer jiffies based. Uses the same clocksource
  10  *   as gtod
  11  *
  12  * Rajeshwarr/Vineetg: Mar 2008
  13  *  -Implemented CONFIG_GENERIC_TIME (rather deleted arch specific code)
  14  *   for arch independent gettimeofday()
  15  *  -Implemented CONFIG_GENERIC_CLOCKEVENTS as base for hrtimers
  16  *
  17  * Vineetg: Mar 2008: Forked off from time.c which now is time-jiff.c
  18  */
  19
  20 /* ARC700 has two 32bit independent prog Timers: TIMER0 and TIMER1
  21  * Each can programmed to go from @count to @limit and optionally
  22  * interrupt when that happens.
  23  * A write to Control Register clears the Interrupt
  24  *
  25  * We've designated TIMER0 for events (clockevents)
  26  * while TIMER1 for free running (clocksource)
  27  *
  28  * Newer ARC700 cores have 64bit clk fetching RTSC insn, preferred over TIMER1
  29  */
  30
  31 #include <linux/spinlock.h>
  32 #include <linux/interrupt.h>
  33 #include <linux/module.h>
  34 #include <linux/sched.h>
  35 #include <linux/kernel.h>
  36 #include <linux/time.h>
  37 #include <linux/init.h>
  38 #include <linux/timex.h>
  39 #include <linux/profile.h>
  40 #include <linux/clocksource.h>
  41 #include <linux/clockchips.h>
  42 #include <asm/irq.h>
  43 #include <asm/arcregs.h>
  44 #include <asm/clk.h>
  45 #include <asm/mach_desc.h>
  46
  47 /* Timer related Aux registers */
  48 #define ARC_REG_TIMER0_LIMIT    0x23    /* timer 0 limit */
  49 #define ARC_REG_TIMER0_CTRL     0x22    /* timer 0 control */
  50 #define ARC_REG_TIMER0_CNT      0x21    /* timer 0 count */
  51 #define ARC_REG_TIMER1_LIMIT    0x102   /* timer 1 limit */
  52 #define ARC_REG_TIMER1_CTRL     0x101   /* timer 1 control */
  53 #define ARC_REG_TIMER1_CNT      0x100   /* timer 1 count */
  54
  55 #define TIMER_CTRL_IE           (1 << 0) /* Interupt when Count reachs limit */
  56 #define TIMER_CTRL_NH           (1 << 1) /* Count only when CPU NOT halted */
  57
  58 #define ARC_TIMER_MAX   0xFFFFFFFF
  59
  60 /********** Clock Source Device *********/
  61
  62 #ifdef CONFIG_ARC_HAS_RTSC
  63
  64 int arc_counter_setup(void)
  65 {
  66         /*
  67          * For SMP this needs to be 0. However Kconfig glue doesn't
  68          * enable this option for SMP configs
  69          */
  70         return 1;
  71 }
  72
  73 static cycle_t arc_counter_read(struct clocksource *cs)
  74 {
  75         unsigned long flags;
  76         union {
  77 #ifdef CONFIG_CPU_BIG_ENDIAN
  78                 struct { u32 high, low; };
  79 #else
  80                 struct { u32 low, high; };
  81 #endif
  82                 cycle_t  full;
  83         } stamp;
  84
  85         flags = arch_local_irq_save();
  86
  87         __asm__ __volatile(
  88         "       .extCoreRegister tsch, 58,  r, cannot_shortcut  \n"
  89         "       rtsc %0, 0      \n"
  90         "       mov  %1, 0      \n"
  91         : "=r" (stamp.low), "=r" (stamp.high));
  92
  93         arch_local_irq_restore(flags);
  94
  95         return stamp.full;
  96 }
  97
  98 static struct clocksource arc_counter = {
  99         .name   = "ARC RTSC",
 100         .rating = 300,
 101         .read   = arc_counter_read,
 102         .mask   = CLOCKSOURCE_MASK(32),
 103         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
 104 };
 105
 106 #else /* !CONFIG_ARC_HAS_RTSC */
 107
 108 static bool is_usable_as_clocksource(void)
 109 {
 110 #ifdef CONFIG_SMP
 111         return 0;
 112 #else
 113         return 1;
 114 #endif
 115 }
 116
 117 /*
 118  * set 32bit TIMER1 to keep counting monotonically and wraparound
 119  */
 120 int arc_counter_setup(void)
 121 {
 122         write_aux_reg(ARC_REG_TIMER1_LIMIT, ARC_TIMER_MAX);
 123         write_aux_reg(ARC_REG_TIMER1_CNT, 0);
 124         write_aux_reg(ARC_REG_TIMER1_CTRL, TIMER_CTRL_NH);
 125
 126         return is_usable_as_clocksource();
 127 }
 128
 129 static cycle_t arc_counter_read(struct clocksource *cs)
 130 {
 131         return (cycle_t) read_aux_reg(ARC_REG_TIMER1_CNT);
 132 }
 133
 134 static struct clocksource arc_counter = {
 135         .name   = "ARC Timer1",
 136         .rating = 300,
 137         .read   = arc_counter_read,
 138         .mask   = CLOCKSOURCE_MASK(32),
 139         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
 140 };
 141
 142 #endif
 143
 144 /********** Clock Event Device *********/
 145
 146 /*
 147  * Arm the timer to interrupt after @limit cycles
 148  * The distinction for oneshot/periodic is done in arc_event_timer_ack() below
 149  */
 150 static void arc_timer_event_setup(unsigned int limit)
 151 {
 152         write_aux_reg(ARC_REG_TIMER0_LIMIT, limit);
 153         write_aux_reg(ARC_REG_TIMER0_CNT, 0);   /* start from 0 */
 154
 155         write_aux_reg(ARC_REG_TIMER0_CTRL, TIMER_CTRL_IE | TIMER_CTRL_NH);
 156 }
 157
 158
 159 static int arc_clkevent_set_next_event(unsigned long delta,
 160                                        struct clock_event_device *dev)
 161 {
 162         arc_timer_event_setup(delta);
 163         return 0;
 164 }
 165
 166 static void arc_clkevent_set_mode(enum clock_event_mode mode,
 167                                   struct clock_event_device *dev)
 168 {
 169         switch (mode) {
 170         case CLOCK_EVT_MODE_PERIODIC:
 171                 arc_timer_event_setup(arc_get_core_freq() / HZ);
 172                 break;
 173         case CLOCK_EVT_MODE_ONESHOT:
 174                 break;
 175         default:
 176                 break;
 177         }
 178
 179         return;
 180 }
 181
 182 static DEFINE_PER_CPU(struct clock_event_device, arc_clockevent_device) = {
 183         .name           = "ARC Timer0",
 184         .features       = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC,
 185         .mode           = CLOCK_EVT_MODE_UNUSED,
 186         .rating         = 300,
 187         .irq            = TIMER0_IRQ,   /* hardwired, no need for resources */
 188         .set_next_event = arc_clkevent_set_next_event,
 189         .set_mode       = arc_clkevent_set_mode,
 190 };
 191
 192 static irqreturn_t timer_irq_handler(int irq, void *dev_id)
 193 {
 194         /*
 195          * Note that generic IRQ core could have passed @evt for @dev_id if
 196          * irq_set_chip_and_handler() asked for handle_percpu_devid_irq()
 197          */
 198         struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
 199         int irq_reenable = evt->mode == CLOCK_EVT_MODE_PERIODIC;
 200
 201         /*
 202          * Any write to CTRL reg ACks the interrupt, we rewrite the
 203          * Count when [N]ot [H]alted bit.
 204          * And re-arm it if perioid by [I]nterrupt [E]nable bit
 205          */
 206         write_aux_reg(ARC_REG_TIMER0_CTRL, irq_reenable | TIMER_CTRL_NH);
 207
 208         evt->event_handler(evt);
 209
 210         return IRQ_HANDLED;
 211 }
 212
 213 /*
 214  * Setup the local event timer for @cpu
 215  */
 216 void arc_local_timer_setup()
 217 {
 218         struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
 219         int cpu = smp_processor_id();
 220
 221         evt->cpumask = cpumask_of(cpu);
 222         clockevents_config_and_register(evt, arc_get_core_freq(),
 223                                         0, ARC_TIMER_MAX);
 224
 225         /* setup the per-cpu timer IRQ handler - for all cpus */
 226         arc_request_percpu_irq(TIMER0_IRQ, cpu, timer_irq_handler,
 227                                "Timer0 (per-cpu-tick)", evt);
 228 }
 229
 230 /*
 231  * Called from start_kernel() - boot CPU only
 232  *
 233  * -Sets up h/w timers as applicable on boot cpu
 234  * -Also sets up any global state needed for timer subsystem:
 235  *    - for "counting" timer, registers a clocksource, usable across CPUs
 236  *      (provided that underlying counter h/w is synchronized across cores)
 237  *    - for "event" timer, sets up TIMER0 IRQ (as that is platform agnostic)
 238  */
 239 void __init time_init(void)
 240 {
 241         /*
 242          * sets up the timekeeping free-flowing counter which also returns
 243          * whether the counter is usable as clocksource
 244          */
 245         if (arc_counter_setup())
 246                 /*
 247                  * CLK upto 4.29 GHz can be safely represented in 32 bits
 248                  * because Max 32 bit number is 4,294,967,295
 249                  */
 250                 clocksource_register_hz(&arc_counter, arc_get_core_freq());
 251
 252         /* sets up the periodic event timer */
 253         arc_local_timer_setup();
 254
 255         if (machine_desc->init_time)
 256                 machine_desc->init_time();
 257 }