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_enable(p->clk);
  82         if (ret) {
  83                 dev_err(&p->pdev->dev, "cannot enable clock\n");
  84                 return ret;
  85         }
  86
  87         /* reset the counter */
  88         em_sti_write(p, STI_SET_H, 0x40000000);
  89         em_sti_write(p, STI_SET_L, 0x00000000);
  90
  91         /* mask and clear pending interrupts */
  92         em_sti_write(p, STI_INTENCLR, 3);
  93         em_sti_write(p, STI_INTFFCLR, 3);
  94
  95         /* enable updates of counter registers */
  96         em_sti_write(p, STI_CONTROL, 1);
  97
  98         return 0;
  99 }
 100
 101 static void em_sti_disable(struct em_sti_priv *p)
 102 {
 103         /* mask interrupts */
 104         em_sti_write(p, STI_INTENCLR, 3);
 105
 106         /* stop clock */
 107         clk_disable(p->clk);
 108 }
 109
 110 static u64 em_sti_count(struct em_sti_priv *p)
 111 {
 112         u64 ticks;
 113         unsigned long flags;
 114
 115         /* the STI hardware buffers the 48-bit count, but to
 116          * break it out into two 32-bit access the registers
 117          * must be accessed in a certain order.
 118          * Always read STI_COUNT_H before STI_COUNT_L.
 119          */
 120         raw_spin_lock_irqsave(&p->lock, flags);
 121         ticks = (u64)(em_sti_read(p, STI_COUNT_H) & 0xffff) << 32;
 122         ticks |= em_sti_read(p, STI_COUNT_L);
 123         raw_spin_unlock_irqrestore(&p->lock, flags);
 124
 125         return ticks;
 126 }
 127
 128 static u64 em_sti_set_next(struct em_sti_priv *p, u64 next)
 129 {
 130         unsigned long flags;
 131
 132         raw_spin_lock_irqsave(&p->lock, flags);
 133
 134         /* mask compare A interrupt */
 135         em_sti_write(p, STI_INTENCLR, 1);
 136
 137         /* update compare A value */
 138         em_sti_write(p, STI_COMPA_H, next >> 32);
 139         em_sti_write(p, STI_COMPA_L, next & 0xffffffff);
 140
 141         /* clear compare A interrupt source */
 142         em_sti_write(p, STI_INTFFCLR, 1);
 143
 144         /* unmask compare A interrupt */
 145         em_sti_write(p, STI_INTENSET, 1);
 146
 147         raw_spin_unlock_irqrestore(&p->lock, flags);
 148
 149         return next;
 150 }
 151
 152 static irqreturn_t em_sti_interrupt(int irq, void *dev_id)
 153 {
 154         struct em_sti_priv *p = dev_id;
 155
 156         p->ced.event_handler(&p->ced);
 157         return IRQ_HANDLED;
 158 }
 159
 160 static int em_sti_start(struct em_sti_priv *p, unsigned int user)
 161 {
 162         unsigned long flags;
 163         int used_before;
 164         int ret = 0;
 165
 166         raw_spin_lock_irqsave(&p->lock, flags);
 167         used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
 168         if (!used_before)
 169                 ret = em_sti_enable(p);
 170
 171         if (!ret)
 172                 p->active[user] = 1;
 173         raw_spin_unlock_irqrestore(&p->lock, flags);
 174
 175         return ret;
 176 }
 177
 178 static void em_sti_stop(struct em_sti_priv *p, unsigned int user)
 179 {
 180         unsigned long flags;
 181         int used_before, used_after;
 182
 183         raw_spin_lock_irqsave(&p->lock, flags);
 184         used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
 185         p->active[user] = 0;
 186         used_after = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
 187
 188         if (used_before && !used_after)
 189                 em_sti_disable(p);
 190         raw_spin_unlock_irqrestore(&p->lock, flags);
 191 }
 192
 193 static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs)
 194 {
 195         return container_of(cs, struct em_sti_priv, cs);
 196 }
 197
 198 static u64 em_sti_clocksource_read(struct clocksource *cs)
 199 {
 200         return em_sti_count(cs_to_em_sti(cs));
 201 }
 202
 203 static int em_sti_clocksource_enable(struct clocksource *cs)
 204 {
 205         struct em_sti_priv *p = cs_to_em_sti(cs);
 206
 207         return em_sti_start(p, USER_CLOCKSOURCE);
 208 }
 209
 210 static void em_sti_clocksource_disable(struct clocksource *cs)
 211 {
 212         em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE);
 213 }
 214
 215 static void em_sti_clocksource_resume(struct clocksource *cs)
 216 {
 217         em_sti_clocksource_enable(cs);
 218 }
 219
 220 static int em_sti_register_clocksource(struct em_sti_priv *p)
 221 {
 222         struct clocksource *cs = &p->cs;
 223
 224         cs->name = dev_name(&p->pdev->dev);
 225         cs->rating = 200;
 226         cs->read = em_sti_clocksource_read;
 227         cs->enable = em_sti_clocksource_enable;
 228         cs->disable = em_sti_clocksource_disable;
 229         cs->suspend = em_sti_clocksource_disable;
 230         cs->resume = em_sti_clocksource_resume;
 231         cs->mask = CLOCKSOURCE_MASK(48);
 232         cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
 233
 234         dev_info(&p->pdev->dev, "used as clock source\n");
 235
 236         clocksource_register_hz(cs, p->rate);
 237         return 0;
 238 }
 239
 240 static struct em_sti_priv *ced_to_em_sti(struct clock_event_device *ced)
 241 {
 242         return container_of(ced, struct em_sti_priv, ced);
 243 }
 244
 245 static int em_sti_clock_event_shutdown(struct clock_event_device *ced)
 246 {
 247         struct em_sti_priv *p = ced_to_em_sti(ced);
 248         em_sti_stop(p, USER_CLOCKEVENT);
 249         return 0;
 250 }
 251
 252 static int em_sti_clock_event_set_oneshot(struct clock_event_device *ced)
 253 {
 254         struct em_sti_priv *p = ced_to_em_sti(ced);
 255
 256         dev_info(&p->pdev->dev, "used for oneshot clock events\n");
 257         em_sti_start(p, USER_CLOCKEVENT);
 258         return 0;
 259 }
 260
 261 static int em_sti_clock_event_next(unsigned long delta,
 262                                    struct clock_event_device *ced)
 263 {
 264         struct em_sti_priv *p = ced_to_em_sti(ced);
 265         u64 next;
 266         int safe;
 267
 268         next = em_sti_set_next(p, em_sti_count(p) + delta);
 269         safe = em_sti_count(p) < (next - 1);
 270
 271         return !safe;
 272 }
 273
 274 static void em_sti_register_clockevent(struct em_sti_priv *p)
 275 {
 276         struct clock_event_device *ced = &p->ced;
 277
 278         ced->name = dev_name(&p->pdev->dev);
 279         ced->features = CLOCK_EVT_FEAT_ONESHOT;
 280         ced->rating = 200;
 281         ced->cpumask = cpu_possible_mask;
 282         ced->set_next_event = em_sti_clock_event_next;
 283         ced->set_state_shutdown = em_sti_clock_event_shutdown;
 284         ced->set_state_oneshot = em_sti_clock_event_set_oneshot;
 285
 286         dev_info(&p->pdev->dev, "used for clock events\n");
 287
 288         clockevents_config_and_register(ced, p->rate, 2, 0xffffffff);
 289 }
 290
 291 static int em_sti_probe(struct platform_device *pdev)
 292 {
 293         struct em_sti_priv *p;
 294         struct resource *res;
 295         int irq;
 296         int ret;
 297
 298         p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
 299         if (p == NULL)
 300                 return -ENOMEM;
 301
 302         p->pdev = pdev;
 303         platform_set_drvdata(pdev, p);
 304
 305         irq = platform_get_irq(pdev, 0);
 306         if (irq < 0) {
 307                 dev_err(&pdev->dev, "failed to get irq\n");
 308                 return irq;
 309         }
 310
 311         /* map memory, let base point to the STI instance */
 312         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 313         p->base = devm_ioremap_resource(&pdev->dev, res);
 314         if (IS_ERR(p->base))
 315                 return PTR_ERR(p->base);
 316
 317         ret = devm_request_irq(&pdev->dev, irq, em_sti_interrupt,
 318                                IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING,
 319                                dev_name(&pdev->dev), p);
 320         if (ret) {
 321                 dev_err(&pdev->dev, "failed to request low IRQ\n");
 322                 return ret;
 323         }
 324
 325         /* get hold of clock */
 326         p->clk = devm_clk_get(&pdev->dev, "sclk");
 327         if (IS_ERR(p->clk)) {
 328                 dev_err(&pdev->dev, "cannot get clock\n");
 329                 return PTR_ERR(p->clk);
 330         }
 331
 332         ret = clk_prepare(p->clk);
 333         if (ret < 0) {
 334                 dev_err(&pdev->dev, "cannot prepare clock\n");
 335                 return ret;
 336         }
 337
 338         ret = clk_enable(p->clk);
 339         if (ret < 0) {
 340                 dev_err(&p->pdev->dev, "cannot enable clock\n");
 341                 clk_unprepare(p->clk);
 342                 return ret;
 343         }
 344         p->rate = clk_get_rate(p->clk);
 345         clk_disable(p->clk);
 346
 347         raw_spin_lock_init(&p->lock);
 348         em_sti_register_clockevent(p);
 349         em_sti_register_clocksource(p);
 350         return 0;
 351 }
 352
 353 static int em_sti_remove(struct platform_device *pdev)
 354 {
 355         return -EBUSY; /* cannot unregister clockevent and clocksource */
 356 }
 357
 358 static const struct of_device_id em_sti_dt_ids[] = {
 359         { .compatible = "renesas,em-sti", },
 360         {},
 361 };
 362 MODULE_DEVICE_TABLE(of, em_sti_dt_ids);
 363
 364 static struct platform_driver em_sti_device_driver = {
 365         .probe          = em_sti_probe,
 366         .remove         = em_sti_remove,
 367         .driver         = {
 368                 .name   = "em_sti",
 369                 .of_match_table = em_sti_dt_ids,
 370         }
 371 };
 372
 373 static int __init em_sti_init(void)
 374 {
 375         return platform_driver_register(&em_sti_device_driver);
 376 }
 377
 378 static void __exit em_sti_exit(void)
 379 {
 380         platform_driver_unregister(&em_sti_device_driver);
 381 }
 382
 383 subsys_initcall(em_sti_init);
 384 module_exit(em_sti_exit);
 385
 386 MODULE_AUTHOR("Magnus Damm");
 387 MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver");
 388 MODULE_LICENSE("GPL v2");