drivers/clocksource/arc_timer.c

   1 /*
   2  * Copyright (C) 2016-17 Synopsys, Inc. (www.synopsys.com)
   3  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 /* ARC700 has two 32bit independent prog Timers: TIMER0 and TIMER1, Each can be
  11  * programmed to go from @count to @limit and optionally interrupt.
  12  * We've designated TIMER0 for clockevents and TIMER1 for clocksource
  13  *
  14  * ARCv2 based HS38 cores have RTC (in-core) and GFRC (inside ARConnect/MCIP)
  15  * which are suitable for UP and SMP based clocksources respectively
  16  */
  17
  18 #include <linux/interrupt.h>
  19 #include <linux/clk.h>
  20 #include <linux/clk-provider.h>
  21 #include <linux/clocksource.h>
  22 #include <linux/clockchips.h>
  23 #include <linux/cpu.h>
  24 #include <linux/of.h>
  25 #include <linux/of_irq.h>
  26
  27 #include <soc/arc/timers.h>
  28 #include <soc/arc/mcip.h>
  29
  30
  31 static unsigned long arc_timer_freq;
  32
  33 static int noinline arc_get_timer_clk(struct device_node *node)
  34 {
  35         struct clk *clk;
  36         int ret;
  37
  38         clk = of_clk_get(node, 0);
  39         if (IS_ERR(clk)) {
  40                 pr_err("timer missing clk\n");
  41                 return PTR_ERR(clk);
  42         }
  43
  44         ret = clk_prepare_enable(clk);
  45         if (ret) {
  46                 pr_err("Couldn't enable parent clk\n");
  47                 return ret;
  48         }
  49
  50         arc_timer_freq = clk_get_rate(clk);
  51
  52         return 0;
  53 }
  54
  55 /********** Clock Source Device *********/
  56
  57 #ifdef CONFIG_ARC_TIMERS_64BIT
  58
  59 static u64 arc_read_gfrc(struct clocksource *cs)
  60 {
  61         unsigned long flags;
  62         u32 l, h;
  63
  64         local_irq_save(flags);
  65
  66         __mcip_cmd(CMD_GFRC_READ_LO, 0);
  67         l = read_aux_reg(ARC_REG_MCIP_READBACK);
  68
  69         __mcip_cmd(CMD_GFRC_READ_HI, 0);
  70         h = read_aux_reg(ARC_REG_MCIP_READBACK);
  71
  72         local_irq_restore(flags);
  73
  74         return (((u64)h) << 32) | l;
  75 }
  76
  77 static struct clocksource arc_counter_gfrc = {
  78         .name   = "ARConnect GFRC",
  79         .rating = 400,
  80         .read   = arc_read_gfrc,
  81         .mask   = CLOCKSOURCE_MASK(64),
  82         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
  83 };
  84
  85 static int __init arc_cs_setup_gfrc(struct device_node *node)
  86 {
  87         struct mcip_bcr mp;
  88         int ret;
  89
  90         READ_BCR(ARC_REG_MCIP_BCR, mp);
  91         if (!mp.gfrc) {
  92                 pr_warn("Global-64-bit-Ctr clocksource not detected\n");
  93                 return -ENXIO;
  94         }
  95
  96         ret = arc_get_timer_clk(node);
  97         if (ret)
  98                 return ret;
  99
 100         return clocksource_register_hz(&arc_counter_gfrc, arc_timer_freq);
 101 }
 102 TIMER_OF_DECLARE(arc_gfrc, "snps,archs-timer-gfrc", arc_cs_setup_gfrc);
 103
 104 #define AUX_RTC_CTRL    0x103
 105 #define AUX_RTC_LOW     0x104
 106 #define AUX_RTC_HIGH    0x105
 107
 108 static u64 arc_read_rtc(struct clocksource *cs)
 109 {
 110         unsigned long status;
 111         u32 l, h;
 112
 113         /*
 114          * hardware has an internal state machine which tracks readout of
 115          * low/high and updates the CTRL.status if
 116          *  - interrupt/exception taken between the two reads
 117          *  - high increments after low has been read
 118          */
 119         do {
 120                 l = read_aux_reg(AUX_RTC_LOW);
 121                 h = read_aux_reg(AUX_RTC_HIGH);
 122                 status = read_aux_reg(AUX_RTC_CTRL);
 123         } while (!(status & _BITUL(31)));
 124
 125         return (((u64)h) << 32) | l;
 126 }
 127
 128 static struct clocksource arc_counter_rtc = {
 129         .name   = "ARCv2 RTC",
 130         .rating = 350,
 131         .read   = arc_read_rtc,
 132         .mask   = CLOCKSOURCE_MASK(64),
 133         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
 134 };
 135
 136 static int __init arc_cs_setup_rtc(struct device_node *node)
 137 {
 138         struct bcr_timer timer;
 139         int ret;
 140
 141         READ_BCR(ARC_REG_TIMERS_BCR, timer);
 142         if (!timer.rtc) {
 143                 pr_warn("Local-64-bit-Ctr clocksource not detected\n");
 144                 return -ENXIO;
 145         }
 146
 147         /* Local to CPU hence not usable in SMP */
 148         if (IS_ENABLED(CONFIG_SMP)) {
 149                 pr_warn("Local-64-bit-Ctr not usable in SMP\n");
 150                 return -EINVAL;
 151         }
 152
 153         ret = arc_get_timer_clk(node);
 154         if (ret)
 155                 return ret;
 156
 157         write_aux_reg(AUX_RTC_CTRL, 1);
 158
 159         return clocksource_register_hz(&arc_counter_rtc, arc_timer_freq);
 160 }
 161 TIMER_OF_DECLARE(arc_rtc, "snps,archs-timer-rtc", arc_cs_setup_rtc);
 162
 163 #endif
 164
 165 /*
 166  * 32bit TIMER1 to keep counting monotonically and wraparound
 167  */
 168
 169 static u64 arc_read_timer1(struct clocksource *cs)
 170 {
 171         return (u64) read_aux_reg(ARC_REG_TIMER1_CNT);
 172 }
 173
 174 static struct clocksource arc_counter_timer1 = {
 175         .name   = "ARC Timer1",
 176         .rating = 300,
 177         .read   = arc_read_timer1,
 178         .mask   = CLOCKSOURCE_MASK(32),
 179         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
 180 };
 181
 182 static int __init arc_cs_setup_timer1(struct device_node *node)
 183 {
 184         int ret;
 185
 186         /* Local to CPU hence not usable in SMP */
 187         if (IS_ENABLED(CONFIG_SMP))
 188                 return -EINVAL;
 189
 190         ret = arc_get_timer_clk(node);
 191         if (ret)
 192                 return ret;
 193
 194         write_aux_reg(ARC_REG_TIMER1_LIMIT, ARC_TIMERN_MAX);
 195         write_aux_reg(ARC_REG_TIMER1_CNT, 0);
 196         write_aux_reg(ARC_REG_TIMER1_CTRL, TIMER_CTRL_NH);
 197
 198         return clocksource_register_hz(&arc_counter_timer1, arc_timer_freq);
 199 }
 200
 201 /********** Clock Event Device *********/
 202
 203 static int arc_timer_irq;
 204
 205 /*
 206  * Arm the timer to interrupt after @cycles
 207  * The distinction for oneshot/periodic is done in arc_event_timer_ack() below
 208  */
 209 static void arc_timer_event_setup(unsigned int cycles)
 210 {
 211         write_aux_reg(ARC_REG_TIMER0_LIMIT, cycles);
 212         write_aux_reg(ARC_REG_TIMER0_CNT, 0);   /* start from 0 */
 213
 214         write_aux_reg(ARC_REG_TIMER0_CTRL, TIMER_CTRL_IE | TIMER_CTRL_NH);
 215 }
 216
 217
 218 static int arc_clkevent_set_next_event(unsigned long delta,
 219                                        struct clock_event_device *dev)
 220 {
 221         arc_timer_event_setup(delta);
 222         return 0;
 223 }
 224
 225 static int arc_clkevent_set_periodic(struct clock_event_device *dev)
 226 {
 227         /*
 228          * At X Hz, 1 sec = 1000ms -> X cycles;
 229          *                    10ms -> X / 100 cycles
 230          */
 231         arc_timer_event_setup(arc_timer_freq / HZ);
 232         return 0;
 233 }
 234
 235 static DEFINE_PER_CPU(struct clock_event_device, arc_clockevent_device) = {
 236         .name                   = "ARC Timer0",
 237         .features               = CLOCK_EVT_FEAT_ONESHOT |
 238                                   CLOCK_EVT_FEAT_PERIODIC,
 239         .rating                 = 300,
 240         .set_next_event         = arc_clkevent_set_next_event,
 241         .set_state_periodic     = arc_clkevent_set_periodic,
 242 };
 243
 244 static irqreturn_t timer_irq_handler(int irq, void *dev_id)
 245 {
 246         /*
 247          * Note that generic IRQ core could have passed @evt for @dev_id if
 248          * irq_set_chip_and_handler() asked for handle_percpu_devid_irq()
 249          */
 250         struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
 251         int irq_reenable = clockevent_state_periodic(evt);
 252
 253         /*
 254          * Any write to CTRL reg ACks the interrupt, we rewrite the
 255          * Count when [N]ot [H]alted bit.
 256          * And re-arm it if perioid by [I]nterrupt [E]nable bit
 257          */
 258         write_aux_reg(ARC_REG_TIMER0_CTRL, irq_reenable | TIMER_CTRL_NH);
 259
 260         evt->event_handler(evt);
 261
 262         return IRQ_HANDLED;
 263 }
 264
 265
 266 static int arc_timer_starting_cpu(unsigned int cpu)
 267 {
 268         struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
 269
 270         evt->cpumask = cpumask_of(smp_processor_id());
 271
 272         clockevents_config_and_register(evt, arc_timer_freq, 0, ARC_TIMERN_MAX);
 273         enable_percpu_irq(arc_timer_irq, 0);
 274         return 0;
 275 }
 276
 277 static int arc_timer_dying_cpu(unsigned int cpu)
 278 {
 279         disable_percpu_irq(arc_timer_irq);
 280         return 0;
 281 }
 282
 283 /*
 284  * clockevent setup for boot CPU
 285  */
 286 static int __init arc_clockevent_setup(struct device_node *node)
 287 {
 288         struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
 289         int ret;
 290
 291         arc_timer_irq = irq_of_parse_and_map(node, 0);
 292         if (arc_timer_irq <= 0) {
 293                 pr_err("clockevent: missing irq\n");
 294                 return -EINVAL;
 295         }
 296
 297         ret = arc_get_timer_clk(node);
 298         if (ret) {
 299                 pr_err("clockevent: missing clk\n");
 300                 return ret;
 301         }
 302
 303         /* Needs apriori irq_set_percpu_devid() done in intc map function */
 304         ret = request_percpu_irq(arc_timer_irq, timer_irq_handler,
 305                                  "Timer0 (per-cpu-tick)", evt);
 306         if (ret) {
 307                 pr_err("clockevent: unable to request irq\n");
 308                 return ret;
 309         }
 310
 311         ret = cpuhp_setup_state(CPUHP_AP_ARC_TIMER_STARTING,
 312                                 "clockevents/arc/timer:starting",
 313                                 arc_timer_starting_cpu,
 314                                 arc_timer_dying_cpu);
 315         if (ret) {
 316                 pr_err("Failed to setup hotplug state\n");
 317                 return ret;
 318         }
 319         return 0;
 320 }
 321
 322 static int __init arc_of_timer_init(struct device_node *np)
 323 {
 324         static int init_count = 0;
 325         int ret;
 326
 327         if (!init_count) {
 328                 init_count = 1;
 329                 ret = arc_clockevent_setup(np);
 330         } else {
 331                 ret = arc_cs_setup_timer1(np);
 332         }
 333
 334         return ret;
 335 }
 336 TIMER_OF_DECLARE(arc_clkevt, "snps,arc-timer", arc_of_timer_init);