linux/drivers/clocksource/em_sti.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Emma Mobile Timer Support - STI
   4 *
   5 *  Copyright (C) 2012 Magnus Damm
   6 */
   7
   8#include <linux/init.h>
   9#include <linux/platform_device.h>
  10#include <linux/spinlock.h>
  11#include <linux/interrupt.h>
  12#include <linux/ioport.h>
  13#include <linux/io.h>
  14#include <linux/clk.h>
  15#include <linux/irq.h>
  16#include <linux/err.h>
  17#include <linux/delay.h>
  18#include <linux/clocksource.h>
  19#include <linux/clockchips.h>
  20#include <linux/slab.h>
  21#include <linux/module.h>
  22
  23enum { USER_CLOCKSOURCE, USER_CLOCKEVENT, USER_NR };
  24
  25struct em_sti_priv {
  26        void __iomem *base;
  27        struct clk *clk;
  28        struct platform_device *pdev;
  29        unsigned int active[USER_NR];
  30        unsigned long rate;
  31        raw_spinlock_t lock;
  32        struct clock_event_device ced;
  33        struct clocksource cs;
  34};
  35
  36#define STI_CONTROL 0x00
  37#define STI_COMPA_H 0x10
  38#define STI_COMPA_L 0x14
  39#define STI_COMPB_H 0x18
  40#define STI_COMPB_L 0x1c
  41#define STI_COUNT_H 0x20
  42#define STI_COUNT_L 0x24
  43#define STI_COUNT_RAW_H 0x28
  44#define STI_COUNT_RAW_L 0x2c
  45#define STI_SET_H 0x30
  46#define STI_SET_L 0x34
  47#define STI_INTSTATUS 0x40
  48#define STI_INTRAWSTATUS 0x44
  49#define STI_INTENSET 0x48
  50#define STI_INTENCLR 0x4c
  51#define STI_INTFFCLR 0x50
  52
  53static inline unsigned long em_sti_read(struct em_sti_priv *p, int offs)
  54{
  55        return ioread32(p->base + offs);
  56}
  57
  58static inline void em_sti_write(struct em_sti_priv *p, int offs,
  59                                unsigned long value)
  60{
  61        iowrite32(value, p->base + offs);
  62}
  63
  64static int em_sti_enable(struct em_sti_priv *p)
  65{
  66        int ret;
  67
  68        /* enable clock */
  69        ret = clk_enable(p->clk);
  70        if (ret) {
  71                dev_err(&p->pdev->dev, "cannot enable clock\n");
  72                return ret;
  73        }
  74
  75        /* reset the counter */
  76        em_sti_write(p, STI_SET_H, 0x40000000);
  77        em_sti_write(p, STI_SET_L, 0x00000000);
  78
  79        /* mask and clear pending interrupts */
  80        em_sti_write(p, STI_INTENCLR, 3);
  81        em_sti_write(p, STI_INTFFCLR, 3);
  82
  83        /* enable updates of counter registers */
  84        em_sti_write(p, STI_CONTROL, 1);
  85
  86        return 0;
  87}
  88
  89static void em_sti_disable(struct em_sti_priv *p)
  90{
  91        /* mask interrupts */
  92        em_sti_write(p, STI_INTENCLR, 3);
  93
  94        /* stop clock */
  95        clk_disable(p->clk);
  96}
  97
  98static u64 em_sti_count(struct em_sti_priv *p)
  99{
 100        u64 ticks;
 101        unsigned long flags;
 102
 103        /* the STI hardware buffers the 48-bit count, but to
 104         * break it out into two 32-bit access the registers
 105         * must be accessed in a certain order.
 106         * Always read STI_COUNT_H before STI_COUNT_L.
 107         */
 108        raw_spin_lock_irqsave(&p->lock, flags);
 109        ticks = (u64)(em_sti_read(p, STI_COUNT_H) & 0xffff) << 32;
 110        ticks |= em_sti_read(p, STI_COUNT_L);
 111        raw_spin_unlock_irqrestore(&p->lock, flags);
 112
 113        return ticks;
 114}
 115
 116static u64 em_sti_set_next(struct em_sti_priv *p, u64 next)
 117{
 118        unsigned long flags;
 119
 120        raw_spin_lock_irqsave(&p->lock, flags);
 121
 122        /* mask compare A interrupt */
 123        em_sti_write(p, STI_INTENCLR, 1);
 124
 125        /* update compare A value */
 126        em_sti_write(p, STI_COMPA_H, next >> 32);
 127        em_sti_write(p, STI_COMPA_L, next & 0xffffffff);
 128
 129        /* clear compare A interrupt source */
 130        em_sti_write(p, STI_INTFFCLR, 1);
 131
 132        /* unmask compare A interrupt */
 133        em_sti_write(p, STI_INTENSET, 1);
 134
 135        raw_spin_unlock_irqrestore(&p->lock, flags);
 136
 137        return next;
 138}
 139
 140static irqreturn_t em_sti_interrupt(int irq, void *dev_id)
 141{
 142        struct em_sti_priv *p = dev_id;
 143
 144        p->ced.event_handler(&p->ced);
 145        return IRQ_HANDLED;
 146}
 147
 148static int em_sti_start(struct em_sti_priv *p, unsigned int user)
 149{
 150        unsigned long flags;
 151        int used_before;
 152        int ret = 0;
 153
 154        raw_spin_lock_irqsave(&p->lock, flags);
 155        used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
 156        if (!used_before)
 157                ret = em_sti_enable(p);
 158
 159        if (!ret)
 160                p->active[user] = 1;
 161        raw_spin_unlock_irqrestore(&p->lock, flags);
 162
 163        return ret;
 164}
 165
 166static void em_sti_stop(struct em_sti_priv *p, unsigned int user)
 167{
 168        unsigned long flags;
 169        int used_before, used_after;
 170
 171        raw_spin_lock_irqsave(&p->lock, flags);
 172        used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
 173        p->active[user] = 0;
 174        used_after = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
 175
 176        if (used_before && !used_after)
 177                em_sti_disable(p);
 178        raw_spin_unlock_irqrestore(&p->lock, flags);
 179}
 180
 181static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs)
 182{
 183        return container_of(cs, struct em_sti_priv, cs);
 184}
 185
 186static u64 em_sti_clocksource_read(struct clocksource *cs)
 187{
 188        return em_sti_count(cs_to_em_sti(cs));
 189}
 190
 191static int em_sti_clocksource_enable(struct clocksource *cs)
 192{
 193        struct em_sti_priv *p = cs_to_em_sti(cs);
 194
 195        return em_sti_start(p, USER_CLOCKSOURCE);
 196}
 197
 198static void em_sti_clocksource_disable(struct clocksource *cs)
 199{
 200        em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE);
 201}
 202
 203static void em_sti_clocksource_resume(struct clocksource *cs)
 204{
 205        em_sti_clocksource_enable(cs);
 206}
 207
 208static int em_sti_register_clocksource(struct em_sti_priv *p)
 209{
 210        struct clocksource *cs = &p->cs;
 211
 212        cs->name = dev_name(&p->pdev->dev);
 213        cs->rating = 200;
 214        cs->read = em_sti_clocksource_read;
 215        cs->enable = em_sti_clocksource_enable;
 216        cs->disable = em_sti_clocksource_disable;
 217        cs->suspend = em_sti_clocksource_disable;
 218        cs->resume = em_sti_clocksource_resume;
 219        cs->mask = CLOCKSOURCE_MASK(48);
 220        cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
 221
 222        dev_info(&p->pdev->dev, "used as clock source\n");
 223
 224        clocksource_register_hz(cs, p->rate);
 225        return 0;
 226}
 227
 228static struct em_sti_priv *ced_to_em_sti(struct clock_event_device *ced)
 229{
 230        return container_of(ced, struct em_sti_priv, ced);
 231}
 232
 233static int em_sti_clock_event_shutdown(struct clock_event_device *ced)
 234{
 235        struct em_sti_priv *p = ced_to_em_sti(ced);
 236        em_sti_stop(p, USER_CLOCKEVENT);
 237        return 0;
 238}
 239
 240static int em_sti_clock_event_set_oneshot(struct clock_event_device *ced)
 241{
 242        struct em_sti_priv *p = ced_to_em_sti(ced);
 243
 244        dev_info(&p->pdev->dev, "used for oneshot clock events\n");
 245        em_sti_start(p, USER_CLOCKEVENT);
 246        return 0;
 247}
 248
 249static int em_sti_clock_event_next(unsigned long delta,
 250                                   struct clock_event_device *ced)
 251{
 252        struct em_sti_priv *p = ced_to_em_sti(ced);
 253        u64 next;
 254        int safe;
 255
 256        next = em_sti_set_next(p, em_sti_count(p) + delta);
 257        safe = em_sti_count(p) < (next - 1);
 258
 259        return !safe;
 260}
 261
 262static void em_sti_register_clockevent(struct em_sti_priv *p)
 263{
 264        struct clock_event_device *ced = &p->ced;
 265
 266        ced->name = dev_name(&p->pdev->dev);
 267        ced->features = CLOCK_EVT_FEAT_ONESHOT;
 268        ced->rating = 200;
 269        ced->cpumask = cpu_possible_mask;
 270        ced->set_next_event = em_sti_clock_event_next;
 271        ced->set_state_shutdown = em_sti_clock_event_shutdown;
 272        ced->set_state_oneshot = em_sti_clock_event_set_oneshot;
 273
 274        dev_info(&p->pdev->dev, "used for clock events\n");
 275
 276        clockevents_config_and_register(ced, p->rate, 2, 0xffffffff);
 277}
 278
 279static int em_sti_probe(struct platform_device *pdev)
 280{
 281        struct em_sti_priv *p;
 282        struct resource *res;
 283        int irq;
 284        int ret;
 285
 286        p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
 287        if (p == NULL)
 288                return -ENOMEM;
 289
 290        p->pdev = pdev;
 291        platform_set_drvdata(pdev, p);
 292
 293        irq = platform_get_irq(pdev, 0);
 294        if (irq < 0)
 295                return irq;
 296
 297        /* map memory, let base point to the STI instance */
 298        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 299        p->base = devm_ioremap_resource(&pdev->dev, res);
 300        if (IS_ERR(p->base))
 301                return PTR_ERR(p->base);
 302
 303        ret = devm_request_irq(&pdev->dev, irq, em_sti_interrupt,
 304                               IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING,
 305                               dev_name(&pdev->dev), p);
 306        if (ret) {
 307                dev_err(&pdev->dev, "failed to request low IRQ\n");
 308                return ret;
 309        }
 310
 311        /* get hold of clock */
 312        p->clk = devm_clk_get(&pdev->dev, "sclk");
 313        if (IS_ERR(p->clk)) {
 314                dev_err(&pdev->dev, "cannot get clock\n");
 315                return PTR_ERR(p->clk);
 316        }
 317
 318        ret = clk_prepare(p->clk);
 319        if (ret < 0) {
 320                dev_err(&pdev->dev, "cannot prepare clock\n");
 321                return ret;
 322        }
 323
 324        ret = clk_enable(p->clk);
 325        if (ret < 0) {
 326                dev_err(&p->pdev->dev, "cannot enable clock\n");
 327                clk_unprepare(p->clk);
 328                return ret;
 329        }
 330        p->rate = clk_get_rate(p->clk);
 331        clk_disable(p->clk);
 332
 333        raw_spin_lock_init(&p->lock);
 334        em_sti_register_clockevent(p);
 335        em_sti_register_clocksource(p);
 336        return 0;
 337}
 338
 339static int em_sti_remove(struct platform_device *pdev)
 340{
 341        return -EBUSY; /* cannot unregister clockevent and clocksource */
 342}
 343
 344static const struct of_device_id em_sti_dt_ids[] = {
 345        { .compatible = "renesas,em-sti", },
 346        {},
 347};
 348MODULE_DEVICE_TABLE(of, em_sti_dt_ids);
 349
 350static struct platform_driver em_sti_device_driver = {
 351        .probe          = em_sti_probe,
 352        .remove         = em_sti_remove,
 353        .driver         = {
 354                .name   = "em_sti",
 355                .of_match_table = em_sti_dt_ids,
 356        }
 357};
 358
 359static int __init em_sti_init(void)
 360{
 361        return platform_driver_register(&em_sti_device_driver);
 362}
 363
 364static void __exit em_sti_exit(void)
 365{
 366        platform_driver_unregister(&em_sti_device_driver);
 367}
 368
 369subsys_initcall(em_sti_init);
 370module_exit(em_sti_exit);
 371
 372MODULE_AUTHOR("Magnus Damm");
 373MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver");
 374MODULE_LICENSE("GPL v2");
 375