drivers/clocksource/em_sti.c

   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
  35 enum { USER_CLOCKSOURCE, USER_CLOCKEVENT, USER_NR };
  36
  37 struct 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
  65 static inline unsigned long em_sti_read(struct em_sti_priv *p, int offs)
  66 {
  67         return ioread32(p->base + offs);
  68 }
  69
  70 static 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
  76 static int em_sti_enable(struct em_sti_priv *p)
  77 {
  78         int ret;
  79
  80         /* enable clock */
  81         ret = clk_prepare_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
 104 static 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_unprepare(p->clk);
 111 }
 112
 113 static 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
 131 static 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
 155 static 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
 163 static 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
 181 static 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
 196 static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs)
 197 {
 198         return container_of(cs, struct em_sti_priv, cs);
 199 }
 200
 201 static cycle_t em_sti_clocksource_read(struct clocksource *cs)
 202 {
 203         return em_sti_count(cs_to_em_sti(cs));
 204 }
 205
 206 static 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_update_freq_hz(cs, p->rate);
 214         return ret;
 215 }
 216
 217 static void em_sti_clocksource_disable(struct clocksource *cs)
 218 {
 219         em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE);
 220 }
 221
 222 static void em_sti_clocksource_resume(struct clocksource *cs)
 223 {
 224         em_sti_clocksource_enable(cs);
 225 }
 226
 227 static int em_sti_register_clocksource(struct em_sti_priv *p)
 228 {
 229         struct clocksource *cs = &p->cs;
 230
 231         cs->name = dev_name(&p->pdev->dev);
 232         cs->rating = 200;
 233         cs->read = em_sti_clocksource_read;
 234         cs->enable = em_sti_clocksource_enable;
 235         cs->disable = em_sti_clocksource_disable;
 236         cs->suspend = em_sti_clocksource_disable;
 237         cs->resume = em_sti_clocksource_resume;
 238         cs->mask = CLOCKSOURCE_MASK(48);
 239         cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
 240
 241         dev_info(&p->pdev->dev, "used as clock source\n");
 242
 243         /* Register with dummy 1 Hz value, gets updated in ->enable() */
 244         clocksource_register_hz(cs, 1);
 245         return 0;
 246 }
 247
 248 static struct em_sti_priv *ced_to_em_sti(struct clock_event_device *ced)
 249 {
 250         return container_of(ced, struct em_sti_priv, ced);
 251 }
 252
 253 static int em_sti_clock_event_shutdown(struct clock_event_device *ced)
 254 {
 255         struct em_sti_priv *p = ced_to_em_sti(ced);
 256         em_sti_stop(p, USER_CLOCKEVENT);
 257         return 0;
 258 }
 259
 260 static int em_sti_clock_event_set_oneshot(struct clock_event_device *ced)
 261 {
 262         struct em_sti_priv *p = ced_to_em_sti(ced);
 263
 264         dev_info(&p->pdev->dev, "used for oneshot clock events\n");
 265         em_sti_start(p, USER_CLOCKEVENT);
 266         clockevents_config(&p->ced, p->rate);
 267         return 0;
 268 }
 269
 270 static int em_sti_clock_event_next(unsigned long delta,
 271                                    struct clock_event_device *ced)
 272 {
 273         struct em_sti_priv *p = ced_to_em_sti(ced);
 274         cycle_t next;
 275         int safe;
 276
 277         next = em_sti_set_next(p, em_sti_count(p) + delta);
 278         safe = em_sti_count(p) < (next - 1);
 279
 280         return !safe;
 281 }
 282
 283 static void em_sti_register_clockevent(struct em_sti_priv *p)
 284 {
 285         struct clock_event_device *ced = &p->ced;
 286
 287         ced->name = dev_name(&p->pdev->dev);
 288         ced->features = CLOCK_EVT_FEAT_ONESHOT;
 289         ced->rating = 200;
 290         ced->cpumask = cpu_possible_mask;
 291         ced->set_next_event = em_sti_clock_event_next;
 292         ced->set_state_shutdown = em_sti_clock_event_shutdown;
 293         ced->set_state_oneshot = em_sti_clock_event_set_oneshot;
 294
 295         dev_info(&p->pdev->dev, "used for clock events\n");
 296
 297         /* Register with dummy 1 Hz value, gets updated in ->set_state_oneshot() */
 298         clockevents_config_and_register(ced, 1, 2, 0xffffffff);
 299 }
 300
 301 static int em_sti_probe(struct platform_device *pdev)
 302 {
 303         struct em_sti_priv *p;
 304         struct resource *res;
 305         int irq;
 306
 307         p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
 308         if (p == NULL)
 309                 return -ENOMEM;
 310
 311         p->pdev = pdev;
 312         platform_set_drvdata(pdev, p);
 313
 314         irq = platform_get_irq(pdev, 0);
 315         if (irq < 0) {
 316                 dev_err(&pdev->dev, "failed to get irq\n");
 317                 return -EINVAL;
 318         }
 319
 320         /* map memory, let base point to the STI instance */
 321         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 322         p->base = devm_ioremap_resource(&pdev->dev, res);
 323         if (IS_ERR(p->base))
 324                 return PTR_ERR(p->base);
 325
 326         /* get hold of clock */
 327         p->clk = devm_clk_get(&pdev->dev, "sclk");
 328         if (IS_ERR(p->clk)) {
 329                 dev_err(&pdev->dev, "cannot get clock\n");
 330                 return PTR_ERR(p->clk);
 331         }
 332
 333         if (devm_request_irq(&pdev->dev, irq, em_sti_interrupt,
 334                              IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING,
 335                              dev_name(&pdev->dev), p)) {
 336                 dev_err(&pdev->dev, "failed to request low IRQ\n");
 337                 return -ENOENT;
 338         }
 339
 340         raw_spin_lock_init(&p->lock);
 341         em_sti_register_clockevent(p);
 342         em_sti_register_clocksource(p);
 343         return 0;
 344 }
 345
 346 static int em_sti_remove(struct platform_device *pdev)
 347 {
 348         return -EBUSY; /* cannot unregister clockevent and clocksource */
 349 }
 350
 351 static const struct of_device_id em_sti_dt_ids[] = {
 352         { .compatible = "renesas,em-sti", },
 353         {},
 354 };
 355 MODULE_DEVICE_TABLE(of, em_sti_dt_ids);
 356
 357 static struct platform_driver em_sti_device_driver = {
 358         .probe          = em_sti_probe,
 359         .remove         = em_sti_remove,
 360         .driver         = {
 361                 .name   = "em_sti",
 362                 .of_match_table = em_sti_dt_ids,
 363         }
 364 };
 365
 366 static int __init em_sti_init(void)
 367 {
 368         return platform_driver_register(&em_sti_device_driver);
 369 }
 370
 371 static void __exit em_sti_exit(void)
 372 {
 373         platform_driver_unregister(&em_sti_device_driver);
 374 }
 375
 376 subsys_initcall(em_sti_init);
 377 module_exit(em_sti_exit);
 378
 379 MODULE_AUTHOR("Magnus Damm");
 380 MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver");
 381 MODULE_LICENSE("GPL v2");