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/interrupt.h>
  12 #include <linux/clockchips.h>
  13 #include <linux/clocksource.h>
  14 #include <linux/delay.h>
  15 #include <linux/of.h>
  16 #include <linux/of_address.h>
  17 #include <linux/of_irq.h>
  18 #include <linux/io.h>
  19 #include <linux/slab.h>
  20
  21 #define ALTERA_TIMER_STATUS_REG         0
  22 #define ALTERA_TIMER_CONTROL_REG        4
  23 #define ALTERA_TIMER_PERIODL_REG        8
  24 #define ALTERA_TIMER_PERIODH_REG        12
  25 #define ALTERA_TIMER_SNAPL_REG          16
  26 #define ALTERA_TIMER_SNAPH_REG          20
  27
  28 #define ALTERA_TIMER_CONTROL_ITO_MSK    (0x1)
  29 #define ALTERA_TIMER_CONTROL_CONT_MSK   (0x2)
  30 #define ALTERA_TIMER_CONTROL_START_MSK  (0x4)
  31 #define ALTERA_TIMER_CONTROL_STOP_MSK   (0x8)
  32
  33 struct nios2_timer {
  34         void __iomem *base;
  35         unsigned long freq;
  36         int irq;
  37 };
  38
  39 struct nios2_clockevent_dev {
  40         struct nios2_timer timer;
  41         struct clock_event_device ced;
  42 };
  43
  44 struct nios2_clocksource {
  45         struct nios2_timer timer;
  46         struct clocksource cs;
  47 };
  48
  49 static inline struct nios2_clockevent_dev *
  50         to_nios2_clkevent(struct clock_event_device *evt)
  51 {
  52         return container_of(evt, struct nios2_clockevent_dev, ced);
  53 }
  54
  55 static inline struct nios2_clocksource *
  56         to_nios2_clksource(struct clocksource *cs)
  57 {
  58         return container_of(cs, struct nios2_clocksource, cs);
  59 }
  60
  61 static u16 timer_readw(struct nios2_timer *timer, u32 offs)
  62 {
  63         return readw(timer->base + offs);
  64 }
  65
  66 static void timer_writew(struct nios2_timer *timer, u16 val, u32 offs)
  67 {
  68         writew(val, timer->base + offs);
  69 }
  70
  71 static inline unsigned long read_timersnapshot(struct nios2_timer *timer)
  72 {
  73         unsigned long count;
  74
  75         timer_writew(timer, 0, ALTERA_TIMER_SNAPL_REG);
  76         count = timer_readw(timer, ALTERA_TIMER_SNAPH_REG) << 16 |
  77                 timer_readw(timer, ALTERA_TIMER_SNAPL_REG);
  78
  79         return count;
  80 }
  81
  82 static cycle_t nios2_timer_read(struct clocksource *cs)
  83 {
  84         struct nios2_clocksource *nios2_cs = to_nios2_clksource(cs);
  85         unsigned long flags;
  86         u32 count;
  87
  88         local_irq_save(flags);
  89         count = read_timersnapshot(&nios2_cs->timer);
  90         local_irq_restore(flags);
  91
  92         /* Counter is counting down */
  93         return ~count;
  94 }
  95
  96 static struct nios2_clocksource nios2_cs = {
  97         .cs = {
  98                 .name   = "nios2-clksrc",
  99                 .rating = 250,
 100                 .read   = nios2_timer_read,
 101                 .mask   = CLOCKSOURCE_MASK(32),
 102                 .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
 103         },
 104 };
 105
 106 cycles_t get_cycles(void)
 107 {
 108         return nios2_timer_read(&nios2_cs.cs);
 109 }
 110
 111 static void nios2_timer_start(struct nios2_timer *timer)
 112 {
 113         u16 ctrl;
 114
 115         ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
 116         ctrl |= ALTERA_TIMER_CONTROL_START_MSK;
 117         timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
 118 }
 119
 120 static void nios2_timer_stop(struct nios2_timer *timer)
 121 {
 122         u16 ctrl;
 123
 124         ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
 125         ctrl |= ALTERA_TIMER_CONTROL_STOP_MSK;
 126         timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
 127 }
 128
 129 static void nios2_timer_config(struct nios2_timer *timer, unsigned long period,
 130         enum clock_event_mode mode)
 131 {
 132         u16 ctrl;
 133
 134         /* The timer's actual period is one cycle greater than the value
 135          * stored in the period register. */
 136          period--;
 137
 138         ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
 139         /* stop counter */
 140         timer_writew(timer, ctrl | ALTERA_TIMER_CONTROL_STOP_MSK,
 141                 ALTERA_TIMER_CONTROL_REG);
 142
 143         /* write new count */
 144         timer_writew(timer, period, ALTERA_TIMER_PERIODL_REG);
 145         timer_writew(timer, period >> 16, ALTERA_TIMER_PERIODH_REG);
 146
 147         ctrl |= ALTERA_TIMER_CONTROL_START_MSK | ALTERA_TIMER_CONTROL_ITO_MSK;
 148         if (mode == CLOCK_EVT_MODE_PERIODIC)
 149                 ctrl |= ALTERA_TIMER_CONTROL_CONT_MSK;
 150         else
 151                 ctrl &= ~ALTERA_TIMER_CONTROL_CONT_MSK;
 152         timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
 153 }
 154
 155 static int nios2_timer_set_next_event(unsigned long delta,
 156         struct clock_event_device *evt)
 157 {
 158         struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
 159
 160         nios2_timer_config(&nios2_ced->timer, delta, evt->mode);
 161
 162         return 0;
 163 }
 164
 165 static void nios2_timer_set_mode(enum clock_event_mode mode,
 166         struct clock_event_device *evt)
 167 {
 168         unsigned long period;
 169         struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
 170         struct nios2_timer *timer = &nios2_ced->timer;
 171
 172         switch (mode) {
 173         case CLOCK_EVT_MODE_PERIODIC:
 174                 period = DIV_ROUND_UP(timer->freq, HZ);
 175                 nios2_timer_config(timer, period, CLOCK_EVT_MODE_PERIODIC);
 176                 break;
 177         case CLOCK_EVT_MODE_ONESHOT:
 178         case CLOCK_EVT_MODE_UNUSED:
 179         case CLOCK_EVT_MODE_SHUTDOWN:
 180                 nios2_timer_stop(timer);
 181                 break;
 182         case CLOCK_EVT_MODE_RESUME:
 183                 nios2_timer_start(timer);
 184                 break;
 185         }
 186 }
 187
 188 irqreturn_t timer_interrupt(int irq, void *dev_id)
 189 {
 190         struct clock_event_device *evt = (struct clock_event_device *) dev_id;
 191         struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
 192
 193         /* Clear the interrupt condition */
 194         timer_writew(&nios2_ced->timer, 0, ALTERA_TIMER_STATUS_REG);
 195         evt->event_handler(evt);
 196
 197         return IRQ_HANDLED;
 198 }
 199
 200 static void __init nios2_timer_get_base_and_freq(struct device_node *np,
 201                                 void __iomem **base, u32 *freq)
 202 {
 203         *base = of_iomap(np, 0);
 204         if (!*base)
 205                 panic("Unable to map reg for %s\n", np->name);
 206
 207         if (of_property_read_u32(np, "clock-frequency", freq))
 208                 panic("Unable to get %s clock frequency\n", np->name);
 209 }
 210
 211 static struct nios2_clockevent_dev nios2_ce = {
 212         .ced = {
 213                 .name = "nios2-clkevent",
 214                 .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 215                 .rating = 250,
 216                 .shift = 32,
 217                 .set_next_event = nios2_timer_set_next_event,
 218                 .set_mode = nios2_timer_set_mode,
 219         },
 220 };
 221
 222 static __init void nios2_clockevent_init(struct device_node *timer)
 223 {
 224         void __iomem *iobase;
 225         u32 freq;
 226         int irq;
 227
 228         nios2_timer_get_base_and_freq(timer, &iobase, &freq);
 229
 230         irq = irq_of_parse_and_map(timer, 0);
 231         if (!irq)
 232                 panic("Unable to parse timer irq\n");
 233
 234         nios2_ce.timer.base = iobase;
 235         nios2_ce.timer.irq = irq;
 236         nios2_ce.timer.freq = freq;
 237
 238         nios2_ce.ced.cpumask = cpumask_of(0);
 239         nios2_ce.ced.irq = irq;
 240
 241         nios2_timer_stop(&nios2_ce.timer);
 242         /* clear pending interrupt */
 243         timer_writew(&nios2_ce.timer, 0, ALTERA_TIMER_STATUS_REG);
 244
 245         if (request_irq(irq, timer_interrupt, IRQF_TIMER, timer->name,
 246                 &nios2_ce.ced))
 247                 panic("Unable to setup timer irq\n");
 248
 249         clockevents_config_and_register(&nios2_ce.ced, freq, 1, ULONG_MAX);
 250 }
 251
 252 static __init void nios2_clocksource_init(struct device_node *timer)
 253 {
 254         unsigned int ctrl;
 255         void __iomem *iobase;
 256         u32 freq;
 257
 258         nios2_timer_get_base_and_freq(timer, &iobase, &freq);
 259
 260         nios2_cs.timer.base = iobase;
 261         nios2_cs.timer.freq = freq;
 262
 263         clocksource_register_hz(&nios2_cs.cs, freq);
 264
 265         timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODL_REG);
 266         timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODH_REG);
 267
 268         /* interrupt disable + continuous + start */
 269         ctrl = ALTERA_TIMER_CONTROL_CONT_MSK | ALTERA_TIMER_CONTROL_START_MSK;
 270         timer_writew(&nios2_cs.timer, ctrl, ALTERA_TIMER_CONTROL_REG);
 271
 272         /* Calibrate the delay loop directly */
 273         lpj_fine = freq / HZ;
 274 }
 275
 276 /*
 277  * The first timer instance will use as a clockevent. If there are two or
 278  * more instances, the second one gets used as clocksource and all
 279  * others are unused.
 280 */
 281 static void __init nios2_time_init(struct device_node *timer)
 282 {
 283         static int num_called;
 284
 285         switch (num_called) {
 286         case 0:
 287                 nios2_clockevent_init(timer);
 288                 break;
 289         case 1:
 290                 nios2_clocksource_init(timer);
 291                 break;
 292         default:
 293                 break;
 294         }
 295
 296         num_called++;
 297 }
 298
 299 void read_persistent_clock(struct timespec *ts)
 300 {
 301         ts->tv_sec = mktime(2007, 1, 1, 0, 0, 0);
 302         ts->tv_nsec = 0;
 303 }
 304
 305 void __init time_init(void)
 306 {
 307         clocksource_of_init();
 308 }
 309
 310 CLOCKSOURCE_OF_DECLARE(nios2_timer, "altr,timer-1.0", nios2_time_init);