arch/nios2/kernel/time.c

   1 /*
   2  * Copyright (C) 2013-2014 Altera Corporation
   3  * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
   4  * Copyright (C) 2004 Microtronix Datacom Ltd.
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License. See the file "COPYING" in the main directory of this archive
   8  * for more details.
   9  */
  10
  11 #include <linux/export.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/clockchips.h>
  14 #include <linux/clocksource.h>
  15 #include <linux/delay.h>
  16 #include <linux/of.h>
  17 #include <linux/of_address.h>
  18 #include <linux/of_irq.h>
  19 #include <linux/io.h>
  20 #include <linux/slab.h>
  21
  22 #define ALTR_TIMER_COMPATIBLE           "altr,timer-1.0"
  23
  24 #define ALTERA_TIMER_STATUS_REG 0
  25 #define ALTERA_TIMER_CONTROL_REG        4
  26 #define ALTERA_TIMER_PERIODL_REG        8
  27 #define ALTERA_TIMER_PERIODH_REG        12
  28 #define ALTERA_TIMER_SNAPL_REG          16
  29 #define ALTERA_TIMER_SNAPH_REG          20
  30
  31 #define ALTERA_TIMER_CONTROL_ITO_MSK    (0x1)
  32 #define ALTERA_TIMER_CONTROL_CONT_MSK   (0x2)
  33 #define ALTERA_TIMER_CONTROL_START_MSK  (0x4)
  34 #define ALTERA_TIMER_CONTROL_STOP_MSK   (0x8)
  35
  36 struct nios2_timer {
  37         void __iomem *base;
  38         unsigned long freq;
  39 };
  40
  41 struct nios2_clockevent_dev {
  42         struct nios2_timer timer;
  43         struct clock_event_device ced;
  44 };
  45
  46 struct nios2_clocksource {
  47         struct nios2_timer timer;
  48         struct clocksource cs;
  49 };
  50
  51 static inline struct nios2_clockevent_dev *
  52         to_nios2_clkevent(struct clock_event_device *evt)
  53 {
  54         return container_of(evt, struct nios2_clockevent_dev, ced);
  55 }
  56
  57 static inline struct nios2_clocksource *
  58         to_nios2_clksource(struct clocksource *cs)
  59 {
  60         return container_of(cs, struct nios2_clocksource, cs);
  61 }
  62
  63 static u16 timer_readw(struct nios2_timer *timer, u32 offs)
  64 {
  65         return readw(timer->base + offs);
  66 }
  67
  68 static void timer_writew(struct nios2_timer *timer, u16 val, u32 offs)
  69 {
  70         writew(val, timer->base + offs);
  71 }
  72
  73 static inline unsigned long read_timersnapshot(struct nios2_timer *timer)
  74 {
  75         unsigned long count;
  76
  77         timer_writew(timer, 0, ALTERA_TIMER_SNAPL_REG);
  78         count = timer_readw(timer, ALTERA_TIMER_SNAPH_REG) << 16 |
  79                 timer_readw(timer, ALTERA_TIMER_SNAPL_REG);
  80
  81         return count;
  82 }
  83
  84 static cycle_t nios2_timer_read(struct clocksource *cs)
  85 {
  86         struct nios2_clocksource *nios2_cs = to_nios2_clksource(cs);
  87         unsigned long flags;
  88         u32 count;
  89
  90         local_irq_save(flags);
  91         count = read_timersnapshot(&nios2_cs->timer);
  92         local_irq_restore(flags);
  93
  94         /* Counter is counting down */
  95         return ~count;
  96 }
  97
  98 static struct nios2_clocksource nios2_cs = {
  99         .cs = {
 100                 .name   = "nios2-clksrc",
 101                 .rating = 250,
 102                 .read   = nios2_timer_read,
 103                 .mask   = CLOCKSOURCE_MASK(32),
 104                 .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
 105         },
 106 };
 107
 108 cycles_t get_cycles(void)
 109 {
 110         return nios2_timer_read(&nios2_cs.cs);
 111 }
 112 EXPORT_SYMBOL(get_cycles);
 113
 114 static void nios2_timer_start(struct nios2_timer *timer)
 115 {
 116         u16 ctrl;
 117
 118         ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
 119         ctrl |= ALTERA_TIMER_CONTROL_START_MSK;
 120         timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
 121 }
 122
 123 static void nios2_timer_stop(struct nios2_timer *timer)
 124 {
 125         u16 ctrl;
 126
 127         ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
 128         ctrl |= ALTERA_TIMER_CONTROL_STOP_MSK;
 129         timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
 130 }
 131
 132 static void nios2_timer_config(struct nios2_timer *timer, unsigned long period,
 133                                bool periodic)
 134 {
 135         u16 ctrl;
 136
 137         /* The timer's actual period is one cycle greater than the value
 138          * stored in the period register. */
 139          period--;
 140
 141         ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
 142         /* stop counter */
 143         timer_writew(timer, ctrl | ALTERA_TIMER_CONTROL_STOP_MSK,
 144                 ALTERA_TIMER_CONTROL_REG);
 145
 146         /* write new count */
 147         timer_writew(timer, period, ALTERA_TIMER_PERIODL_REG);
 148         timer_writew(timer, period >> 16, ALTERA_TIMER_PERIODH_REG);
 149
 150         ctrl |= ALTERA_TIMER_CONTROL_START_MSK | ALTERA_TIMER_CONTROL_ITO_MSK;
 151         if (periodic)
 152                 ctrl |= ALTERA_TIMER_CONTROL_CONT_MSK;
 153         else
 154                 ctrl &= ~ALTERA_TIMER_CONTROL_CONT_MSK;
 155         timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
 156 }
 157
 158 static int nios2_timer_set_next_event(unsigned long delta,
 159         struct clock_event_device *evt)
 160 {
 161         struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
 162
 163         nios2_timer_config(&nios2_ced->timer, delta, false);
 164
 165         return 0;
 166 }
 167
 168 static int nios2_timer_shutdown(struct clock_event_device *evt)
 169 {
 170         struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
 171         struct nios2_timer *timer = &nios2_ced->timer;
 172
 173         nios2_timer_stop(timer);
 174         return 0;
 175 }
 176
 177 static int nios2_timer_set_periodic(struct clock_event_device *evt)
 178 {
 179         unsigned long period;
 180         struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
 181         struct nios2_timer *timer = &nios2_ced->timer;
 182
 183         period = DIV_ROUND_UP(timer->freq, HZ);
 184         nios2_timer_config(timer, period, true);
 185         return 0;
 186 }
 187
 188 static int nios2_timer_resume(struct clock_event_device *evt)
 189 {
 190         struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
 191         struct nios2_timer *timer = &nios2_ced->timer;
 192
 193         nios2_timer_start(timer);
 194         return 0;
 195 }
 196
 197 irqreturn_t timer_interrupt(int irq, void *dev_id)
 198 {
 199         struct clock_event_device *evt = (struct clock_event_device *) dev_id;
 200         struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
 201
 202         /* Clear the interrupt condition */
 203         timer_writew(&nios2_ced->timer, 0, ALTERA_TIMER_STATUS_REG);
 204         evt->event_handler(evt);
 205
 206         return IRQ_HANDLED;
 207 }
 208
 209 static void __init nios2_timer_get_base_and_freq(struct device_node *np,
 210                                 void __iomem **base, u32 *freq)
 211 {
 212         *base = of_iomap(np, 0);
 213         if (!*base)
 214                 panic("Unable to map reg for %s\n", np->name);
 215
 216         if (of_property_read_u32(np, "clock-frequency", freq))
 217                 panic("Unable to get %s clock frequency\n", np->name);
 218 }
 219
 220 static struct nios2_clockevent_dev nios2_ce = {
 221         .ced = {
 222                 .name = "nios2-clkevent",
 223                 .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 224                 .rating = 250,
 225                 .shift = 32,
 226                 .set_next_event = nios2_timer_set_next_event,
 227                 .set_state_shutdown = nios2_timer_shutdown,
 228                 .set_state_periodic = nios2_timer_set_periodic,
 229                 .set_state_oneshot = nios2_timer_shutdown,
 230                 .tick_resume = nios2_timer_resume,
 231         },
 232 };
 233
 234 static __init void nios2_clockevent_init(struct device_node *timer)
 235 {
 236         void __iomem *iobase;
 237         u32 freq;
 238         int irq;
 239
 240         nios2_timer_get_base_and_freq(timer, &iobase, &freq);
 241
 242         irq = irq_of_parse_and_map(timer, 0);
 243         if (!irq)
 244                 panic("Unable to parse timer irq\n");
 245
 246         nios2_ce.timer.base = iobase;
 247         nios2_ce.timer.freq = freq;
 248
 249         nios2_ce.ced.cpumask = cpumask_of(0);
 250         nios2_ce.ced.irq = irq;
 251
 252         nios2_timer_stop(&nios2_ce.timer);
 253         /* clear pending interrupt */
 254         timer_writew(&nios2_ce.timer, 0, ALTERA_TIMER_STATUS_REG);
 255
 256         if (request_irq(irq, timer_interrupt, IRQF_TIMER, timer->name,
 257                 &nios2_ce.ced))
 258                 panic("Unable to setup timer irq\n");
 259
 260         clockevents_config_and_register(&nios2_ce.ced, freq, 1, ULONG_MAX);
 261 }
 262
 263 static __init void nios2_clocksource_init(struct device_node *timer)
 264 {
 265         unsigned int ctrl;
 266         void __iomem *iobase;
 267         u32 freq;
 268
 269         nios2_timer_get_base_and_freq(timer, &iobase, &freq);
 270
 271         nios2_cs.timer.base = iobase;
 272         nios2_cs.timer.freq = freq;
 273
 274         clocksource_register_hz(&nios2_cs.cs, freq);
 275
 276         timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODL_REG);
 277         timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODH_REG);
 278
 279         /* interrupt disable + continuous + start */
 280         ctrl = ALTERA_TIMER_CONTROL_CONT_MSK | ALTERA_TIMER_CONTROL_START_MSK;
 281         timer_writew(&nios2_cs.timer, ctrl, ALTERA_TIMER_CONTROL_REG);
 282
 283         /* Calibrate the delay loop directly */
 284         lpj_fine = freq / HZ;
 285 }
 286
 287 /*
 288  * The first timer instance will use as a clockevent. If there are two or
 289  * more instances, the second one gets used as clocksource and all
 290  * others are unused.
 291 */
 292 static void __init nios2_time_init(struct device_node *timer)
 293 {
 294         static int num_called;
 295
 296         switch (num_called) {
 297         case 0:
 298                 nios2_clockevent_init(timer);
 299                 break;
 300         case 1:
 301                 nios2_clocksource_init(timer);
 302                 break;
 303         default:
 304                 break;
 305         }
 306
 307         num_called++;
 308 }
 309
 310 void read_persistent_clock(struct timespec *ts)
 311 {
 312         ts->tv_sec = mktime(2007, 1, 1, 0, 0, 0);
 313         ts->tv_nsec = 0;
 314 }
 315
 316 void __init time_init(void)
 317 {
 318         struct device_node *np;
 319         int count = 0;
 320
 321         for_each_compatible_node(np, NULL,  ALTR_TIMER_COMPATIBLE)
 322                 count++;
 323
 324         if (count < 2)
 325                 panic("%d timer is found, it needs 2 timers in system\n", count);
 326
 327         clocksource_probe();
 328 }
 329
 330 CLOCKSOURCE_OF_DECLARE(nios2_timer, ALTR_TIMER_COMPATIBLE, nios2_time_init);