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         enum clock_event_mode mode)
 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 (mode == CLOCK_EVT_MODE_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, evt->mode);
 164
 165         return 0;
 166 }
 167
 168 static void nios2_timer_set_mode(enum clock_event_mode mode,
 169         struct clock_event_device *evt)
 170 {
 171         unsigned long period;
 172         struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
 173         struct nios2_timer *timer = &nios2_ced->timer;
 174
 175         switch (mode) {
 176         case CLOCK_EVT_MODE_PERIODIC:
 177                 period = DIV_ROUND_UP(timer->freq, HZ);
 178                 nios2_timer_config(timer, period, CLOCK_EVT_MODE_PERIODIC);
 179                 break;
 180         case CLOCK_EVT_MODE_ONESHOT:
 181         case CLOCK_EVT_MODE_UNUSED:
 182         case CLOCK_EVT_MODE_SHUTDOWN:
 183                 nios2_timer_stop(timer);
 184                 break;
 185         case CLOCK_EVT_MODE_RESUME:
 186                 nios2_timer_start(timer);
 187                 break;
 188         }
 189 }
 190
 191 irqreturn_t timer_interrupt(int irq, void *dev_id)
 192 {
 193         struct clock_event_device *evt = (struct clock_event_device *) dev_id;
 194         struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
 195
 196         /* Clear the interrupt condition */
 197         timer_writew(&nios2_ced->timer, 0, ALTERA_TIMER_STATUS_REG);
 198         evt->event_handler(evt);
 199
 200         return IRQ_HANDLED;
 201 }
 202
 203 static void __init nios2_timer_get_base_and_freq(struct device_node *np,
 204                                 void __iomem **base, u32 *freq)
 205 {
 206         *base = of_iomap(np, 0);
 207         if (!*base)
 208                 panic("Unable to map reg for %s\n", np->name);
 209
 210         if (of_property_read_u32(np, "clock-frequency", freq))
 211                 panic("Unable to get %s clock frequency\n", np->name);
 212 }
 213
 214 static struct nios2_clockevent_dev nios2_ce = {
 215         .ced = {
 216                 .name = "nios2-clkevent",
 217                 .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 218                 .rating = 250,
 219                 .shift = 32,
 220                 .set_next_event = nios2_timer_set_next_event,
 221                 .set_mode = nios2_timer_set_mode,
 222         },
 223 };
 224
 225 static __init void nios2_clockevent_init(struct device_node *timer)
 226 {
 227         void __iomem *iobase;
 228         u32 freq;
 229         int irq;
 230
 231         nios2_timer_get_base_and_freq(timer, &iobase, &freq);
 232
 233         irq = irq_of_parse_and_map(timer, 0);
 234         if (!irq)
 235                 panic("Unable to parse timer irq\n");
 236
 237         nios2_ce.timer.base = iobase;
 238         nios2_ce.timer.freq = freq;
 239
 240         nios2_ce.ced.cpumask = cpumask_of(0);
 241         nios2_ce.ced.irq = irq;
 242
 243         nios2_timer_stop(&nios2_ce.timer);
 244         /* clear pending interrupt */
 245         timer_writew(&nios2_ce.timer, 0, ALTERA_TIMER_STATUS_REG);
 246
 247         if (request_irq(irq, timer_interrupt, IRQF_TIMER, timer->name,
 248                 &nios2_ce.ced))
 249                 panic("Unable to setup timer irq\n");
 250
 251         clockevents_config_and_register(&nios2_ce.ced, freq, 1, ULONG_MAX);
 252 }
 253
 254 static __init void nios2_clocksource_init(struct device_node *timer)
 255 {
 256         unsigned int ctrl;
 257         void __iomem *iobase;
 258         u32 freq;
 259
 260         nios2_timer_get_base_and_freq(timer, &iobase, &freq);
 261
 262         nios2_cs.timer.base = iobase;
 263         nios2_cs.timer.freq = freq;
 264
 265         clocksource_register_hz(&nios2_cs.cs, freq);
 266
 267         timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODL_REG);
 268         timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODH_REG);
 269
 270         /* interrupt disable + continuous + start */
 271         ctrl = ALTERA_TIMER_CONTROL_CONT_MSK | ALTERA_TIMER_CONTROL_START_MSK;
 272         timer_writew(&nios2_cs.timer, ctrl, ALTERA_TIMER_CONTROL_REG);
 273
 274         /* Calibrate the delay loop directly */
 275         lpj_fine = freq / HZ;
 276 }
 277
 278 /*
 279  * The first timer instance will use as a clockevent. If there are two or
 280  * more instances, the second one gets used as clocksource and all
 281  * others are unused.
 282 */
 283 static void __init nios2_time_init(struct device_node *timer)
 284 {
 285         static int num_called;
 286
 287         switch (num_called) {
 288         case 0:
 289                 nios2_clockevent_init(timer);
 290                 break;
 291         case 1:
 292                 nios2_clocksource_init(timer);
 293                 break;
 294         default:
 295                 break;
 296         }
 297
 298         num_called++;
 299 }
 300
 301 void read_persistent_clock(struct timespec *ts)
 302 {
 303         ts->tv_sec = mktime(2007, 1, 1, 0, 0, 0);
 304         ts->tv_nsec = 0;
 305 }
 306
 307 void __init time_init(void)
 308 {
 309         struct device_node *np;
 310         int count = 0;
 311
 312         for_each_compatible_node(np, NULL,  ALTR_TIMER_COMPATIBLE)
 313                 count++;
 314
 315         if (count < 2)
 316                 panic("%d timer is found, it needs 2 timers in system\n", count);
 317
 318         clocksource_of_init();
 319 }
 320
 321 CLOCKSOURCE_OF_DECLARE(nios2_timer, ALTR_TIMER_COMPATIBLE, nios2_time_init);