drivers/clocksource/arc_timer.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2016-17 Synopsys, Inc. (www.synopsys.com)
   4  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   5  */
   6
   7 /* ARC700 has two 32bit independent prog Timers: TIMER0 and TIMER1, Each can be
   8  * programmed to go from @count to @limit and optionally interrupt.
   9  * We've designated TIMER0 for clockevents and TIMER1 for clocksource
  10  *
  11  * ARCv2 based HS38 cores have RTC (in-core) and GFRC (inside ARConnect/MCIP)
  12  * which are suitable for UP and SMP based clocksources respectively
  13  */
  14
  15 #include <linux/interrupt.h>
  16 #include <linux/bits.h>
  17 #include <linux/clk.h>
  18 #include <linux/clk-provider.h>
  19 #include <linux/clocksource.h>
  20 #include <linux/clockchips.h>
  21 #include <linux/cpu.h>
  22 #include <linux/of.h>
  23 #include <linux/of_irq.h>
  24 #include <linux/sched_clock.h>
  25
  26 #include <soc/arc/timers.h>
  27 #include <soc/arc/mcip.h>
  28
  29
  30 static unsigned long arc_timer_freq;
  31
  32 static int noinline arc_get_timer_clk(struct device_node *node)
  33 {
  34         struct clk *clk;
  35         int ret;
  36
  37         clk = of_clk_get(node, 0);
  38         if (IS_ERR(clk)) {
  39                 pr_err("timer missing clk\n");
  40                 return PTR_ERR(clk);
  41         }
  42
  43         ret = clk_prepare_enable(clk);
  44         if (ret) {
  45                 pr_err("Couldn't enable parent clk\n");
  46                 return ret;
  47         }
  48
  49         arc_timer_freq = clk_get_rate(clk);
  50
  51         return 0;
  52 }
  53
  54 /********** Clock Source Device *********/
  55
  56 #ifdef CONFIG_ARC_TIMERS_64BIT
  57
  58 static u64 arc_read_gfrc(struct clocksource *cs)
  59 {
  60         unsigned long flags;
  61         u32 l, h;
  62
  63         /*
  64          * From a programming model pov, there seems to be just one instance of
  65          * MCIP_CMD/MCIP_READBACK however micro-architecturally there's
  66          * an instance PER ARC CORE (not per cluster), and there are dedicated
  67          * hardware decode logic (per core) inside ARConnect to handle
  68          * simultaneous read/write accesses from cores via those two registers.
  69          * So several concurrent commands to ARConnect are OK if they are
  70          * trying to access two different sub-components (like GFRC,
  71          * inter-core interrupt, etc...). HW also supports simultaneously
  72          * accessing GFRC by multiple cores.
  73          * That's why it is safe to disable hard interrupts on the local CPU
  74          * before access to GFRC instead of taking global MCIP spinlock
  75          * defined in arch/arc/kernel/mcip.c
  76          */
  77         local_irq_save(flags);
  78
  79         __mcip_cmd(CMD_GFRC_READ_LO, 0);
  80         l = read_aux_reg(ARC_REG_MCIP_READBACK);
  81
  82         __mcip_cmd(CMD_GFRC_READ_HI, 0);
  83         h = read_aux_reg(ARC_REG_MCIP_READBACK);
  84
  85         local_irq_restore(flags);
  86
  87         return (((u64)h) << 32) | l;
  88 }
  89
  90 static notrace u64 arc_gfrc_clock_read(void)
  91 {
  92         return arc_read_gfrc(NULL);
  93 }
  94
  95 static struct clocksource arc_counter_gfrc = {
  96         .name   = "ARConnect GFRC",
  97         .rating = 400,
  98         .read   = arc_read_gfrc,
  99         .mask   = CLOCKSOURCE_MASK(64),
 100         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
 101 };
 102
 103 static int __init arc_cs_setup_gfrc(struct device_node *node)
 104 {
 105         struct mcip_bcr mp;
 106         int ret;
 107
 108         READ_BCR(ARC_REG_MCIP_BCR, mp);
 109         if (!mp.gfrc) {
 110                 pr_warn("Global-64-bit-Ctr clocksource not detected\n");
 111                 return -ENXIO;
 112         }
 113
 114         ret = arc_get_timer_clk(node);
 115         if (ret)
 116                 return ret;
 117
 118         sched_clock_register(arc_gfrc_clock_read, 64, arc_timer_freq);
 119
 120         return clocksource_register_hz(&arc_counter_gfrc, arc_timer_freq);
 121 }
 122 TIMER_OF_DECLARE(arc_gfrc, "snps,archs-timer-gfrc", arc_cs_setup_gfrc);
 123
 124 #define AUX_RTC_CTRL    0x103
 125 #define AUX_RTC_LOW     0x104
 126 #define AUX_RTC_HIGH    0x105
 127
 128 static u64 arc_read_rtc(struct clocksource *cs)
 129 {
 130         unsigned long status;
 131         u32 l, h;
 132
 133         /*
 134          * hardware has an internal state machine which tracks readout of
 135          * low/high and updates the CTRL.status if
 136          *  - interrupt/exception taken between the two reads
 137          *  - high increments after low has been read
 138          */
 139         do {
 140                 l = read_aux_reg(AUX_RTC_LOW);
 141                 h = read_aux_reg(AUX_RTC_HIGH);
 142                 status = read_aux_reg(AUX_RTC_CTRL);
 143         } while (!(status & BIT(31)));
 144
 145         return (((u64)h) << 32) | l;
 146 }
 147
 148 static notrace u64 arc_rtc_clock_read(void)
 149 {
 150         return arc_read_rtc(NULL);
 151 }
 152
 153 static struct clocksource arc_counter_rtc = {
 154         .name   = "ARCv2 RTC",
 155         .rating = 350,
 156         .read   = arc_read_rtc,
 157         .mask   = CLOCKSOURCE_MASK(64),
 158         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
 159 };
 160
 161 static int __init arc_cs_setup_rtc(struct device_node *node)
 162 {
 163         struct bcr_timer timer;
 164         int ret;
 165
 166         READ_BCR(ARC_REG_TIMERS_BCR, timer);
 167         if (!timer.rtc) {
 168                 pr_warn("Local-64-bit-Ctr clocksource not detected\n");
 169                 return -ENXIO;
 170         }
 171
 172         /* Local to CPU hence not usable in SMP */
 173         if (IS_ENABLED(CONFIG_SMP)) {
 174                 pr_warn("Local-64-bit-Ctr not usable in SMP\n");
 175                 return -EINVAL;
 176         }
 177
 178         ret = arc_get_timer_clk(node);
 179         if (ret)
 180                 return ret;
 181
 182         write_aux_reg(AUX_RTC_CTRL, 1);
 183
 184         sched_clock_register(arc_rtc_clock_read, 64, arc_timer_freq);
 185
 186         return clocksource_register_hz(&arc_counter_rtc, arc_timer_freq);
 187 }
 188 TIMER_OF_DECLARE(arc_rtc, "snps,archs-timer-rtc", arc_cs_setup_rtc);
 189
 190 #endif
 191
 192 /*
 193  * 32bit TIMER1 to keep counting monotonically and wraparound
 194  */
 195
 196 static u64 arc_read_timer1(struct clocksource *cs)
 197 {
 198         return (u64) read_aux_reg(ARC_REG_TIMER1_CNT);
 199 }
 200
 201 static notrace u64 arc_timer1_clock_read(void)
 202 {
 203         return arc_read_timer1(NULL);
 204 }
 205
 206 static struct clocksource arc_counter_timer1 = {
 207         .name   = "ARC Timer1",
 208         .rating = 300,
 209         .read   = arc_read_timer1,
 210         .mask   = CLOCKSOURCE_MASK(32),
 211         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
 212 };
 213
 214 static int __init arc_cs_setup_timer1(struct device_node *node)
 215 {
 216         int ret;
 217
 218         /* Local to CPU hence not usable in SMP */
 219         if (IS_ENABLED(CONFIG_SMP))
 220                 return -EINVAL;
 221
 222         ret = arc_get_timer_clk(node);
 223         if (ret)
 224                 return ret;
 225
 226         write_aux_reg(ARC_REG_TIMER1_LIMIT, ARC_TIMERN_MAX);
 227         write_aux_reg(ARC_REG_TIMER1_CNT, 0);
 228         write_aux_reg(ARC_REG_TIMER1_CTRL, TIMER_CTRL_NH);
 229
 230         sched_clock_register(arc_timer1_clock_read, 32, arc_timer_freq);
 231
 232         return clocksource_register_hz(&arc_counter_timer1, arc_timer_freq);
 233 }
 234
 235 /********** Clock Event Device *********/
 236
 237 static int arc_timer_irq;
 238
 239 /*
 240  * Arm the timer to interrupt after @cycles
 241  * The distinction for oneshot/periodic is done in arc_event_timer_ack() below
 242  */
 243 static void arc_timer_event_setup(unsigned int cycles)
 244 {
 245         write_aux_reg(ARC_REG_TIMER0_LIMIT, cycles);
 246         write_aux_reg(ARC_REG_TIMER0_CNT, 0);   /* start from 0 */
 247
 248         write_aux_reg(ARC_REG_TIMER0_CTRL, TIMER_CTRL_IE | TIMER_CTRL_NH);
 249 }
 250
 251
 252 static int arc_clkevent_set_next_event(unsigned long delta,
 253                                        struct clock_event_device *dev)
 254 {
 255         arc_timer_event_setup(delta);
 256         return 0;
 257 }
 258
 259 static int arc_clkevent_set_periodic(struct clock_event_device *dev)
 260 {
 261         /*
 262          * At X Hz, 1 sec = 1000ms -> X cycles;
 263          *                    10ms -> X / 100 cycles
 264          */
 265         arc_timer_event_setup(arc_timer_freq / HZ);
 266         return 0;
 267 }
 268
 269 static DEFINE_PER_CPU(struct clock_event_device, arc_clockevent_device) = {
 270         .name                   = "ARC Timer0",
 271         .features               = CLOCK_EVT_FEAT_ONESHOT |
 272                                   CLOCK_EVT_FEAT_PERIODIC,
 273         .rating                 = 300,
 274         .set_next_event         = arc_clkevent_set_next_event,
 275         .set_state_periodic     = arc_clkevent_set_periodic,
 276 };
 277
 278 static irqreturn_t timer_irq_handler(int irq, void *dev_id)
 279 {
 280         /*
 281          * Note that generic IRQ core could have passed @evt for @dev_id if
 282          * irq_set_chip_and_handler() asked for handle_percpu_devid_irq()
 283          */
 284         struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
 285         int irq_reenable = clockevent_state_periodic(evt);
 286
 287         /*
 288          * 1. ACK the interrupt
 289          *    - For ARC700, any write to CTRL reg ACKs it, so just rewrite
 290          *      Count when [N]ot [H]alted bit.
 291          *    - For HS3x, it is a bit subtle. On taken count-down interrupt,
 292          *      IP bit [3] is set, which needs to be cleared for ACK'ing.
 293          *      The write below can only update the other two bits, hence
 294          *      explicitly clears IP bit
 295          * 2. Re-arm interrupt if periodic by writing to IE bit [0]
 296          */
 297         write_aux_reg(ARC_REG_TIMER0_CTRL, irq_reenable | TIMER_CTRL_NH);
 298
 299         evt->event_handler(evt);
 300
 301         return IRQ_HANDLED;
 302 }
 303
 304
 305 static int arc_timer_starting_cpu(unsigned int cpu)
 306 {
 307         struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
 308
 309         evt->cpumask = cpumask_of(smp_processor_id());
 310
 311         clockevents_config_and_register(evt, arc_timer_freq, 0, ARC_TIMERN_MAX);
 312         enable_percpu_irq(arc_timer_irq, 0);
 313         return 0;
 314 }
 315
 316 static int arc_timer_dying_cpu(unsigned int cpu)
 317 {
 318         disable_percpu_irq(arc_timer_irq);
 319         return 0;
 320 }
 321
 322 /*
 323  * clockevent setup for boot CPU
 324  */
 325 static int __init arc_clockevent_setup(struct device_node *node)
 326 {
 327         struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
 328         int ret;
 329
 330         arc_timer_irq = irq_of_parse_and_map(node, 0);
 331         if (arc_timer_irq <= 0) {
 332                 pr_err("clockevent: missing irq\n");
 333                 return -EINVAL;
 334         }
 335
 336         ret = arc_get_timer_clk(node);
 337         if (ret) {
 338                 pr_err("clockevent: missing clk\n");
 339                 return ret;
 340         }
 341
 342         /* Needs apriori irq_set_percpu_devid() done in intc map function */
 343         ret = request_percpu_irq(arc_timer_irq, timer_irq_handler,
 344                                  "Timer0 (per-cpu-tick)", evt);
 345         if (ret) {
 346                 pr_err("clockevent: unable to request irq\n");
 347                 return ret;
 348         }
 349
 350         ret = cpuhp_setup_state(CPUHP_AP_ARC_TIMER_STARTING,
 351                                 "clockevents/arc/timer:starting",
 352                                 arc_timer_starting_cpu,
 353                                 arc_timer_dying_cpu);
 354         if (ret) {
 355                 pr_err("Failed to setup hotplug state\n");
 356                 return ret;
 357         }
 358         return 0;
 359 }
 360
 361 static int __init arc_of_timer_init(struct device_node *np)
 362 {
 363         static int init_count = 0;
 364         int ret;
 365
 366         if (!init_count) {
 367                 init_count = 1;
 368                 ret = arc_clockevent_setup(np);
 369         } else {
 370                 ret = arc_cs_setup_timer1(np);
 371         }
 372
 373         return ret;
 374 }
 375 TIMER_OF_DECLARE(arc_clkevt, "snps,arc-timer", arc_of_timer_init);