linux/drivers/clocksource/em_sti.c
<<
>>
Prefs
   1/*
   2 * Emma Mobile Timer Support - STI
   3 *
   4 *  Copyright (C) 2012 Magnus Damm
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation; either version 2 of the License
   9 *
  10 * This program is distributed in the hope that it will be useful,
  11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 * GNU General Public License for more details.
  14 *
  15 * You should have received a copy of the GNU General Public License
  16 * along with this program; if not, write to the Free Software
  17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18 */
  19
  20#include <linux/init.h>
  21#include <linux/platform_device.h>
  22#include <linux/spinlock.h>
  23#include <linux/interrupt.h>
  24#include <linux/ioport.h>
  25#include <linux/io.h>
  26#include <linux/clk.h>
  27#include <linux/irq.h>
  28#include <linux/err.h>
  29#include <linux/delay.h>
  30#include <linux/clocksource.h>
  31#include <linux/clockchips.h>
  32#include <linux/slab.h>
  33#include <linux/module.h>
  34
  35enum { USER_CLOCKSOURCE, USER_CLOCKEVENT, USER_NR };
  36
  37struct em_sti_priv {
  38        void __iomem *base;
  39        struct clk *clk;
  40        struct platform_device *pdev;
  41        unsigned int active[USER_NR];
  42        unsigned long rate;
  43        raw_spinlock_t lock;
  44        struct clock_event_device ced;
  45        struct clocksource cs;
  46};
  47
  48#define STI_CONTROL 0x00
  49#define STI_COMPA_H 0x10
  50#define STI_COMPA_L 0x14
  51#define STI_COMPB_H 0x18
  52#define STI_COMPB_L 0x1c
  53#define STI_COUNT_H 0x20
  54#define STI_COUNT_L 0x24
  55#define STI_COUNT_RAW_H 0x28
  56#define STI_COUNT_RAW_L 0x2c
  57#define STI_SET_H 0x30
  58#define STI_SET_L 0x34
  59#define STI_INTSTATUS 0x40
  60#define STI_INTRAWSTATUS 0x44
  61#define STI_INTENSET 0x48
  62#define STI_INTENCLR 0x4c
  63#define STI_INTFFCLR 0x50
  64
  65static inline unsigned long em_sti_read(struct em_sti_priv *p, int offs)
  66{
  67        return ioread32(p->base + offs);
  68}
  69
  70static inline void em_sti_write(struct em_sti_priv *p, int offs,
  71                                unsigned long value)
  72{
  73        iowrite32(value, p->base + offs);
  74}
  75
  76static int em_sti_enable(struct em_sti_priv *p)
  77{
  78        int ret;
  79
  80        /* enable clock */
  81        ret = clk_enable(p->clk);
  82        if (ret) {
  83                dev_err(&p->pdev->dev, "cannot enable clock\n");
  84                return ret;
  85        }
  86
  87        /* configure channel, periodic mode and maximum timeout */
  88        p->rate = clk_get_rate(p->clk);
  89
  90        /* reset the counter */
  91        em_sti_write(p, STI_SET_H, 0x40000000);
  92        em_sti_write(p, STI_SET_L, 0x00000000);
  93
  94        /* mask and clear pending interrupts */
  95        em_sti_write(p, STI_INTENCLR, 3);
  96        em_sti_write(p, STI_INTFFCLR, 3);
  97
  98        /* enable updates of counter registers */
  99        em_sti_write(p, STI_CONTROL, 1);
 100
 101        return 0;
 102}
 103
 104static void em_sti_disable(struct em_sti_priv *p)
 105{
 106        /* mask interrupts */
 107        em_sti_write(p, STI_INTENCLR, 3);
 108
 109        /* stop clock */
 110        clk_disable(p->clk);
 111}
 112
 113static cycle_t em_sti_count(struct em_sti_priv *p)
 114{
 115        cycle_t ticks;
 116        unsigned long flags;
 117
 118        /* the STI hardware buffers the 48-bit count, but to
 119         * break it out into two 32-bit access the registers
 120         * must be accessed in a certain order.
 121         * Always read STI_COUNT_H before STI_COUNT_L.
 122         */
 123        raw_spin_lock_irqsave(&p->lock, flags);
 124        ticks = (cycle_t)(em_sti_read(p, STI_COUNT_H) & 0xffff) << 32;
 125        ticks |= em_sti_read(p, STI_COUNT_L);
 126        raw_spin_unlock_irqrestore(&p->lock, flags);
 127
 128        return ticks;
 129}
 130
 131static cycle_t em_sti_set_next(struct em_sti_priv *p, cycle_t next)
 132{
 133        unsigned long flags;
 134
 135        raw_spin_lock_irqsave(&p->lock, flags);
 136
 137        /* mask compare A interrupt */
 138        em_sti_write(p, STI_INTENCLR, 1);
 139
 140        /* update compare A value */
 141        em_sti_write(p, STI_COMPA_H, next >> 32);
 142        em_sti_write(p, STI_COMPA_L, next & 0xffffffff);
 143
 144        /* clear compare A interrupt source */
 145        em_sti_write(p, STI_INTFFCLR, 1);
 146
 147        /* unmask compare A interrupt */
 148        em_sti_write(p, STI_INTENSET, 1);
 149
 150        raw_spin_unlock_irqrestore(&p->lock, flags);
 151
 152        return next;
 153}
 154
 155static irqreturn_t em_sti_interrupt(int irq, void *dev_id)
 156{
 157        struct em_sti_priv *p = dev_id;
 158
 159        p->ced.event_handler(&p->ced);
 160        return IRQ_HANDLED;
 161}
 162
 163static int em_sti_start(struct em_sti_priv *p, unsigned int user)
 164{
 165        unsigned long flags;
 166        int used_before;
 167        int ret = 0;
 168
 169        raw_spin_lock_irqsave(&p->lock, flags);
 170        used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
 171        if (!used_before)
 172                ret = em_sti_enable(p);
 173
 174        if (!ret)
 175                p->active[user] = 1;
 176        raw_spin_unlock_irqrestore(&p->lock, flags);
 177
 178        return ret;
 179}
 180
 181static void em_sti_stop(struct em_sti_priv *p, unsigned int user)
 182{
 183        unsigned long flags;
 184        int used_before, used_after;
 185
 186        raw_spin_lock_irqsave(&p->lock, flags);
 187        used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
 188        p->active[user] = 0;
 189        used_after = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
 190
 191        if (used_before && !used_after)
 192                em_sti_disable(p);
 193        raw_spin_unlock_irqrestore(&p->lock, flags);
 194}
 195
 196static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs)
 197{
 198        return container_of(cs, struct em_sti_priv, cs);
 199}
 200
 201static cycle_t em_sti_clocksource_read(struct clocksource *cs)
 202{
 203        return em_sti_count(cs_to_em_sti(cs));
 204}
 205
 206static int em_sti_clocksource_enable(struct clocksource *cs)
 207{
 208        int ret;
 209        struct em_sti_priv *p = cs_to_em_sti(cs);
 210
 211        ret = em_sti_start(p, USER_CLOCKSOURCE);
 212        if (!ret)
 213                __clocksource_updatefreq_hz(cs, p->rate);
 214        return ret;
 215}
 216
 217static void em_sti_clocksource_disable(struct clocksource *cs)
 218{
 219        em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE);
 220}
 221
 222static void em_sti_clocksource_resume(struct clocksource *cs)
 223{
 224        em_sti_clocksource_enable(cs);
 225}
 226
 227static int em_sti_register_clocksource(struct em_sti_priv *p)
 228{
 229        struct clocksource *cs = &p->cs;
 230
 231        memset(cs, 0, sizeof(*cs));
 232        cs->name = dev_name(&p->pdev->dev);
 233        cs->rating = 200;
 234        cs->read = em_sti_clocksource_read;
 235        cs->enable = em_sti_clocksource_enable;
 236        cs->disable = em_sti_clocksource_disable;
 237        cs->suspend = em_sti_clocksource_disable;
 238        cs->resume = em_sti_clocksource_resume;
 239        cs->mask = CLOCKSOURCE_MASK(48);
 240        cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
 241
 242        dev_info(&p->pdev->dev, "used as clock source\n");
 243
 244        /* Register with dummy 1 Hz value, gets updated in ->enable() */
 245        clocksource_register_hz(cs, 1);
 246        return 0;
 247}
 248
 249static struct em_sti_priv *ced_to_em_sti(struct clock_event_device *ced)
 250{
 251        return container_of(ced, struct em_sti_priv, ced);
 252}
 253
 254static void em_sti_clock_event_mode(enum clock_event_mode mode,
 255                                    struct clock_event_device *ced)
 256{
 257        struct em_sti_priv *p = ced_to_em_sti(ced);
 258
 259        /* deal with old setting first */
 260        switch (ced->mode) {
 261        case CLOCK_EVT_MODE_ONESHOT:
 262                em_sti_stop(p, USER_CLOCKEVENT);
 263                break;
 264        default:
 265                break;
 266        }
 267
 268        switch (mode) {
 269        case CLOCK_EVT_MODE_ONESHOT:
 270                dev_info(&p->pdev->dev, "used for oneshot clock events\n");
 271                em_sti_start(p, USER_CLOCKEVENT);
 272                clockevents_config(&p->ced, p->rate);
 273                break;
 274        case CLOCK_EVT_MODE_SHUTDOWN:
 275        case CLOCK_EVT_MODE_UNUSED:
 276                em_sti_stop(p, USER_CLOCKEVENT);
 277                break;
 278        default:
 279                break;
 280        }
 281}
 282
 283static int em_sti_clock_event_next(unsigned long delta,
 284                                   struct clock_event_device *ced)
 285{
 286        struct em_sti_priv *p = ced_to_em_sti(ced);
 287        cycle_t next;
 288        int safe;
 289
 290        next = em_sti_set_next(p, em_sti_count(p) + delta);
 291        safe = em_sti_count(p) < (next - 1);
 292
 293        return !safe;
 294}
 295
 296static void em_sti_register_clockevent(struct em_sti_priv *p)
 297{
 298        struct clock_event_device *ced = &p->ced;
 299
 300        memset(ced, 0, sizeof(*ced));
 301        ced->name = dev_name(&p->pdev->dev);
 302        ced->features = CLOCK_EVT_FEAT_ONESHOT;
 303        ced->rating = 200;
 304        ced->cpumask = cpumask_of(0);
 305        ced->set_next_event = em_sti_clock_event_next;
 306        ced->set_mode = em_sti_clock_event_mode;
 307
 308        dev_info(&p->pdev->dev, "used for clock events\n");
 309
 310        /* Register with dummy 1 Hz value, gets updated in ->set_mode() */
 311        clockevents_config_and_register(ced, 1, 2, 0xffffffff);
 312}
 313
 314static int __devinit em_sti_probe(struct platform_device *pdev)
 315{
 316        struct em_sti_priv *p;
 317        struct resource *res;
 318        int irq, ret;
 319
 320        p = kzalloc(sizeof(*p), GFP_KERNEL);
 321        if (p == NULL) {
 322                dev_err(&pdev->dev, "failed to allocate driver data\n");
 323                ret = -ENOMEM;
 324                goto err0;
 325        }
 326
 327        p->pdev = pdev;
 328        platform_set_drvdata(pdev, p);
 329
 330        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 331        if (!res) {
 332                dev_err(&pdev->dev, "failed to get I/O memory\n");
 333                ret = -EINVAL;
 334                goto err0;
 335        }
 336
 337        irq = platform_get_irq(pdev, 0);
 338        if (irq < 0) {
 339                dev_err(&pdev->dev, "failed to get irq\n");
 340                ret = -EINVAL;
 341                goto err0;
 342        }
 343
 344        /* map memory, let base point to the STI instance */
 345        p->base = ioremap_nocache(res->start, resource_size(res));
 346        if (p->base == NULL) {
 347                dev_err(&pdev->dev, "failed to remap I/O memory\n");
 348                ret = -ENXIO;
 349                goto err0;
 350        }
 351
 352        /* get hold of clock */
 353        p->clk = clk_get(&pdev->dev, "sclk");
 354        if (IS_ERR(p->clk)) {
 355                dev_err(&pdev->dev, "cannot get clock\n");
 356                ret = PTR_ERR(p->clk);
 357                goto err1;
 358        }
 359
 360        if (request_irq(irq, em_sti_interrupt,
 361                        IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING,
 362                        dev_name(&pdev->dev), p)) {
 363                dev_err(&pdev->dev, "failed to request low IRQ\n");
 364                ret = -ENOENT;
 365                goto err2;
 366        }
 367
 368        raw_spin_lock_init(&p->lock);
 369        em_sti_register_clockevent(p);
 370        em_sti_register_clocksource(p);
 371        return 0;
 372
 373err2:
 374        clk_put(p->clk);
 375err1:
 376        iounmap(p->base);
 377err0:
 378        kfree(p);
 379        return ret;
 380}
 381
 382static int __devexit em_sti_remove(struct platform_device *pdev)
 383{
 384        return -EBUSY; /* cannot unregister clockevent and clocksource */
 385}
 386
 387static const struct of_device_id em_sti_dt_ids[] __devinitconst = {
 388        { .compatible = "renesas,em-sti", },
 389        {},
 390};
 391MODULE_DEVICE_TABLE(of, em_sti_dt_ids);
 392
 393static struct platform_driver em_sti_device_driver = {
 394        .probe          = em_sti_probe,
 395        .remove         = __devexit_p(em_sti_remove),
 396        .driver         = {
 397                .name   = "em_sti",
 398                .of_match_table = em_sti_dt_ids,
 399        }
 400};
 401
 402module_platform_driver(em_sti_device_driver);
 403
 404MODULE_AUTHOR("Magnus Damm");
 405MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver");
 406MODULE_LICENSE("GPL v2");
 407
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.