drivers/clocksource/samsung_pwm_timer.c

   1 /*
   2  * Copyright (c) 2011 Samsung Electronics Co., Ltd.
   3  *              http://www.samsung.com/
   4  *
   5  * samsung - Common hr-timer support (s3c and s5p)
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10 */
  11
  12 #include <linux/interrupt.h>
  13 #include <linux/irq.h>
  14 #include <linux/err.h>
  15 #include <linux/clk.h>
  16 #include <linux/clockchips.h>
  17 #include <linux/list.h>
  18 #include <linux/module.h>
  19 #include <linux/of.h>
  20 #include <linux/of_address.h>
  21 #include <linux/of_irq.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/slab.h>
  24 #include <linux/sched_clock.h>
  25
  26 #include <clocksource/samsung_pwm.h>
  27
  28
  29 /*
  30  * Clocksource driver
  31  */
  32
  33 #define REG_TCFG0                       0x00
  34 #define REG_TCFG1                       0x04
  35 #define REG_TCON                        0x08
  36 #define REG_TINT_CSTAT                  0x44
  37
  38 #define REG_TCNTB(chan)                 (0x0c + 12 * (chan))
  39 #define REG_TCMPB(chan)                 (0x10 + 12 * (chan))
  40
  41 #define TCFG0_PRESCALER_MASK            0xff
  42 #define TCFG0_PRESCALER1_SHIFT          8
  43
  44 #define TCFG1_SHIFT(x)                  ((x) * 4)
  45 #define TCFG1_MUX_MASK                  0xf
  46
  47 /*
  48  * Each channel occupies 4 bits in TCON register, but there is a gap of 4
  49  * bits (one channel) after channel 0, so channels have different numbering
  50  * when accessing TCON register.
  51  *
  52  * In addition, the location of autoreload bit for channel 4 (TCON channel 5)
  53  * in its set of bits is 2 as opposed to 3 for other channels.
  54  */
  55 #define TCON_START(chan)                (1 << (4 * (chan) + 0))
  56 #define TCON_MANUALUPDATE(chan)         (1 << (4 * (chan) + 1))
  57 #define TCON_INVERT(chan)               (1 << (4 * (chan) + 2))
  58 #define _TCON_AUTORELOAD(chan)          (1 << (4 * (chan) + 3))
  59 #define _TCON_AUTORELOAD4(chan)         (1 << (4 * (chan) + 2))
  60 #define TCON_AUTORELOAD(chan)           \
  61         ((chan < 5) ? _TCON_AUTORELOAD(chan) : _TCON_AUTORELOAD4(chan))
  62
  63 DEFINE_SPINLOCK(samsung_pwm_lock);
  64 EXPORT_SYMBOL(samsung_pwm_lock);
  65
  66 struct samsung_pwm_clocksource {
  67         void __iomem *base;
  68         void __iomem *source_reg;
  69         unsigned int irq[SAMSUNG_PWM_NUM];
  70         struct samsung_pwm_variant variant;
  71
  72         struct clk *timerclk;
  73
  74         unsigned int event_id;
  75         unsigned int source_id;
  76         unsigned int tcnt_max;
  77         unsigned int tscaler_div;
  78         unsigned int tdiv;
  79
  80         unsigned long clock_count_per_tick;
  81 };
  82
  83 static struct samsung_pwm_clocksource pwm;
  84
  85 static void samsung_timer_set_prescale(unsigned int channel, u16 prescale)
  86 {
  87         unsigned long flags;
  88         u8 shift = 0;
  89         u32 reg;
  90
  91         if (channel >= 2)
  92                 shift = TCFG0_PRESCALER1_SHIFT;
  93
  94         spin_lock_irqsave(&samsung_pwm_lock, flags);
  95
  96         reg = readl(pwm.base + REG_TCFG0);
  97         reg &= ~(TCFG0_PRESCALER_MASK << shift);
  98         reg |= (prescale - 1) << shift;
  99         writel(reg, pwm.base + REG_TCFG0);
 100
 101         spin_unlock_irqrestore(&samsung_pwm_lock, flags);
 102 }
 103
 104 static void samsung_timer_set_divisor(unsigned int channel, u8 divisor)
 105 {
 106         u8 shift = TCFG1_SHIFT(channel);
 107         unsigned long flags;
 108         u32 reg;
 109         u8 bits;
 110
 111         bits = (fls(divisor) - 1) - pwm.variant.div_base;
 112
 113         spin_lock_irqsave(&samsung_pwm_lock, flags);
 114
 115         reg = readl(pwm.base + REG_TCFG1);
 116         reg &= ~(TCFG1_MUX_MASK << shift);
 117         reg |= bits << shift;
 118         writel(reg, pwm.base + REG_TCFG1);
 119
 120         spin_unlock_irqrestore(&samsung_pwm_lock, flags);
 121 }
 122
 123 static void samsung_time_stop(unsigned int channel)
 124 {
 125         unsigned long tcon;
 126         unsigned long flags;
 127
 128         if (channel > 0)
 129                 ++channel;
 130
 131         spin_lock_irqsave(&samsung_pwm_lock, flags);
 132
 133         tcon = readl_relaxed(pwm.base + REG_TCON);
 134         tcon &= ~TCON_START(channel);
 135         writel_relaxed(tcon, pwm.base + REG_TCON);
 136
 137         spin_unlock_irqrestore(&samsung_pwm_lock, flags);
 138 }
 139
 140 static void samsung_time_setup(unsigned int channel, unsigned long tcnt)
 141 {
 142         unsigned long tcon;
 143         unsigned long flags;
 144         unsigned int tcon_chan = channel;
 145
 146         if (tcon_chan > 0)
 147                 ++tcon_chan;
 148
 149         spin_lock_irqsave(&samsung_pwm_lock, flags);
 150
 151         tcon = readl_relaxed(pwm.base + REG_TCON);
 152
 153         tcon &= ~(TCON_START(tcon_chan) | TCON_AUTORELOAD(tcon_chan));
 154         tcon |= TCON_MANUALUPDATE(tcon_chan);
 155
 156         writel_relaxed(tcnt, pwm.base + REG_TCNTB(channel));
 157         writel_relaxed(tcnt, pwm.base + REG_TCMPB(channel));
 158         writel_relaxed(tcon, pwm.base + REG_TCON);
 159
 160         spin_unlock_irqrestore(&samsung_pwm_lock, flags);
 161 }
 162
 163 static void samsung_time_start(unsigned int channel, bool periodic)
 164 {
 165         unsigned long tcon;
 166         unsigned long flags;
 167
 168         if (channel > 0)
 169                 ++channel;
 170
 171         spin_lock_irqsave(&samsung_pwm_lock, flags);
 172
 173         tcon = readl_relaxed(pwm.base + REG_TCON);
 174
 175         tcon &= ~TCON_MANUALUPDATE(channel);
 176         tcon |= TCON_START(channel);
 177
 178         if (periodic)
 179                 tcon |= TCON_AUTORELOAD(channel);
 180         else
 181                 tcon &= ~TCON_AUTORELOAD(channel);
 182
 183         writel_relaxed(tcon, pwm.base + REG_TCON);
 184
 185         spin_unlock_irqrestore(&samsung_pwm_lock, flags);
 186 }
 187
 188 static int samsung_set_next_event(unsigned long cycles,
 189                                 struct clock_event_device *evt)
 190 {
 191         /*
 192          * This check is needed to account for internal rounding
 193          * errors inside clockevents core, which might result in
 194          * passing cycles = 0, which in turn would not generate any
 195          * timer interrupt and hang the system.
 196          *
 197          * Another solution would be to set up the clockevent device
 198          * with min_delta = 2, but this would unnecessarily increase
 199          * the minimum sleep period.
 200          */
 201         if (!cycles)
 202                 cycles = 1;
 203
 204         samsung_time_setup(pwm.event_id, cycles);
 205         samsung_time_start(pwm.event_id, false);
 206
 207         return 0;
 208 }
 209
 210 static int samsung_shutdown(struct clock_event_device *evt)
 211 {
 212         samsung_time_stop(pwm.event_id);
 213         return 0;
 214 }
 215
 216 static int samsung_set_periodic(struct clock_event_device *evt)
 217 {
 218         samsung_time_stop(pwm.event_id);
 219         samsung_time_setup(pwm.event_id, pwm.clock_count_per_tick - 1);
 220         samsung_time_start(pwm.event_id, true);
 221         return 0;
 222 }
 223
 224 static void samsung_clockevent_resume(struct clock_event_device *cev)
 225 {
 226         samsung_timer_set_prescale(pwm.event_id, pwm.tscaler_div);
 227         samsung_timer_set_divisor(pwm.event_id, pwm.tdiv);
 228
 229         if (pwm.variant.has_tint_cstat) {
 230                 u32 mask = (1 << pwm.event_id);
 231                 writel(mask | (mask << 5), pwm.base + REG_TINT_CSTAT);
 232         }
 233 }
 234
 235 static struct clock_event_device time_event_device = {
 236         .name                   = "samsung_event_timer",
 237         .features               = CLOCK_EVT_FEAT_PERIODIC |
 238                                   CLOCK_EVT_FEAT_ONESHOT,
 239         .rating                 = 200,
 240         .set_next_event         = samsung_set_next_event,
 241         .set_state_shutdown     = samsung_shutdown,
 242         .set_state_periodic     = samsung_set_periodic,
 243         .set_state_oneshot      = samsung_shutdown,
 244         .tick_resume            = samsung_shutdown,
 245         .resume                 = samsung_clockevent_resume,
 246 };
 247
 248 static irqreturn_t samsung_clock_event_isr(int irq, void *dev_id)
 249 {
 250         struct clock_event_device *evt = dev_id;
 251
 252         if (pwm.variant.has_tint_cstat) {
 253                 u32 mask = (1 << pwm.event_id);
 254                 writel(mask | (mask << 5), pwm.base + REG_TINT_CSTAT);
 255         }
 256
 257         evt->event_handler(evt);
 258
 259         return IRQ_HANDLED;
 260 }
 261
 262 static struct irqaction samsung_clock_event_irq = {
 263         .name           = "samsung_time_irq",
 264         .flags          = IRQF_TIMER | IRQF_IRQPOLL,
 265         .handler        = samsung_clock_event_isr,
 266         .dev_id         = &time_event_device,
 267 };
 268
 269 static void __init samsung_clockevent_init(void)
 270 {
 271         unsigned long pclk;
 272         unsigned long clock_rate;
 273         unsigned int irq_number;
 274
 275         pclk = clk_get_rate(pwm.timerclk);
 276
 277         samsung_timer_set_prescale(pwm.event_id, pwm.tscaler_div);
 278         samsung_timer_set_divisor(pwm.event_id, pwm.tdiv);
 279
 280         clock_rate = pclk / (pwm.tscaler_div * pwm.tdiv);
 281         pwm.clock_count_per_tick = clock_rate / HZ;
 282
 283         time_event_device.cpumask = cpumask_of(0);
 284         clockevents_config_and_register(&time_event_device,
 285                                                 clock_rate, 1, pwm.tcnt_max);
 286
 287         irq_number = pwm.irq[pwm.event_id];
 288         setup_irq(irq_number, &samsung_clock_event_irq);
 289
 290         if (pwm.variant.has_tint_cstat) {
 291                 u32 mask = (1 << pwm.event_id);
 292                 writel(mask | (mask << 5), pwm.base + REG_TINT_CSTAT);
 293         }
 294 }
 295
 296 static void samsung_clocksource_suspend(struct clocksource *cs)
 297 {
 298         samsung_time_stop(pwm.source_id);
 299 }
 300
 301 static void samsung_clocksource_resume(struct clocksource *cs)
 302 {
 303         samsung_timer_set_prescale(pwm.source_id, pwm.tscaler_div);
 304         samsung_timer_set_divisor(pwm.source_id, pwm.tdiv);
 305
 306         samsung_time_setup(pwm.source_id, pwm.tcnt_max);
 307         samsung_time_start(pwm.source_id, true);
 308 }
 309
 310 static u64 notrace samsung_clocksource_read(struct clocksource *c)
 311 {
 312         return ~readl_relaxed(pwm.source_reg);
 313 }
 314
 315 static struct clocksource samsung_clocksource = {
 316         .name           = "samsung_clocksource_timer",
 317         .rating         = 250,
 318         .read           = samsung_clocksource_read,
 319         .suspend        = samsung_clocksource_suspend,
 320         .resume         = samsung_clocksource_resume,
 321         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 322 };
 323
 324 /*
 325  * Override the global weak sched_clock symbol with this
 326  * local implementation which uses the clocksource to get some
 327  * better resolution when scheduling the kernel. We accept that
 328  * this wraps around for now, since it is just a relative time
 329  * stamp. (Inspired by U300 implementation.)
 330  */
 331 static u64 notrace samsung_read_sched_clock(void)
 332 {
 333         return samsung_clocksource_read(NULL);
 334 }
 335
 336 static int __init samsung_clocksource_init(void)
 337 {
 338         unsigned long pclk;
 339         unsigned long clock_rate;
 340
 341         pclk = clk_get_rate(pwm.timerclk);
 342
 343         samsung_timer_set_prescale(pwm.source_id, pwm.tscaler_div);
 344         samsung_timer_set_divisor(pwm.source_id, pwm.tdiv);
 345
 346         clock_rate = pclk / (pwm.tscaler_div * pwm.tdiv);
 347
 348         samsung_time_setup(pwm.source_id, pwm.tcnt_max);
 349         samsung_time_start(pwm.source_id, true);
 350
 351         if (pwm.source_id == 4)
 352                 pwm.source_reg = pwm.base + 0x40;
 353         else
 354                 pwm.source_reg = pwm.base + pwm.source_id * 0x0c + 0x14;
 355
 356         sched_clock_register(samsung_read_sched_clock,
 357                                                 pwm.variant.bits, clock_rate);
 358
 359         samsung_clocksource.mask = CLOCKSOURCE_MASK(pwm.variant.bits);
 360         return clocksource_register_hz(&samsung_clocksource, clock_rate);
 361 }
 362
 363 static void __init samsung_timer_resources(void)
 364 {
 365         clk_prepare_enable(pwm.timerclk);
 366
 367         pwm.tcnt_max = (1UL << pwm.variant.bits) - 1;
 368         if (pwm.variant.bits == 16) {
 369                 pwm.tscaler_div = 25;
 370                 pwm.tdiv = 2;
 371         } else {
 372                 pwm.tscaler_div = 2;
 373                 pwm.tdiv = 1;
 374         }
 375 }
 376
 377 /*
 378  * PWM master driver
 379  */
 380 static int __init _samsung_pwm_clocksource_init(void)
 381 {
 382         u8 mask;
 383         int channel;
 384
 385         mask = ~pwm.variant.output_mask & ((1 << SAMSUNG_PWM_NUM) - 1);
 386         channel = fls(mask) - 1;
 387         if (channel < 0) {
 388                 pr_crit("failed to find PWM channel for clocksource\n");
 389                 return -EINVAL;
 390         }
 391         pwm.source_id = channel;
 392
 393         mask &= ~(1 << channel);
 394         channel = fls(mask) - 1;
 395         if (channel < 0) {
 396                 pr_crit("failed to find PWM channel for clock event\n");
 397                 return -EINVAL;
 398         }
 399         pwm.event_id = channel;
 400
 401         samsung_timer_resources();
 402         samsung_clockevent_init();
 403
 404         return samsung_clocksource_init();
 405 }
 406
 407 void __init samsung_pwm_clocksource_init(void __iomem *base,
 408                         unsigned int *irqs, struct samsung_pwm_variant *variant)
 409 {
 410         pwm.base = base;
 411         memcpy(&pwm.variant, variant, sizeof(pwm.variant));
 412         memcpy(pwm.irq, irqs, SAMSUNG_PWM_NUM * sizeof(*irqs));
 413
 414         pwm.timerclk = clk_get(NULL, "timers");
 415         if (IS_ERR(pwm.timerclk))
 416                 panic("failed to get timers clock for timer");
 417
 418         _samsung_pwm_clocksource_init();
 419 }
 420
 421 #ifdef CONFIG_TIMER_OF
 422 static int __init samsung_pwm_alloc(struct device_node *np,
 423                                     const struct samsung_pwm_variant *variant)
 424 {
 425         struct property *prop;
 426         const __be32 *cur;
 427         u32 val;
 428         int i;
 429
 430         memcpy(&pwm.variant, variant, sizeof(pwm.variant));
 431         for (i = 0; i < SAMSUNG_PWM_NUM; ++i)
 432                 pwm.irq[i] = irq_of_parse_and_map(np, i);
 433
 434         of_property_for_each_u32(np, "samsung,pwm-outputs", prop, cur, val) {
 435                 if (val >= SAMSUNG_PWM_NUM) {
 436                         pr_warning("%s: invalid channel index in samsung,pwm-outputs property\n",
 437                                                                 __func__);
 438                         continue;
 439                 }
 440                 pwm.variant.output_mask |= 1 << val;
 441         }
 442
 443         pwm.base = of_iomap(np, 0);
 444         if (!pwm.base) {
 445                 pr_err("%s: failed to map PWM registers\n", __func__);
 446                 return -ENXIO;
 447         }
 448
 449         pwm.timerclk = of_clk_get_by_name(np, "timers");
 450         if (IS_ERR(pwm.timerclk)) {
 451                 pr_crit("failed to get timers clock for timer\n");
 452                 return PTR_ERR(pwm.timerclk);
 453         }
 454
 455         return _samsung_pwm_clocksource_init();
 456 }
 457
 458 static const struct samsung_pwm_variant s3c24xx_variant = {
 459         .bits           = 16,
 460         .div_base       = 1,
 461         .has_tint_cstat = false,
 462         .tclk_mask      = (1 << 4),
 463 };
 464
 465 static int __init s3c2410_pwm_clocksource_init(struct device_node *np)
 466 {
 467         return samsung_pwm_alloc(np, &s3c24xx_variant);
 468 }
 469 TIMER_OF_DECLARE(s3c2410_pwm, "samsung,s3c2410-pwm", s3c2410_pwm_clocksource_init);
 470
 471 static const struct samsung_pwm_variant s3c64xx_variant = {
 472         .bits           = 32,
 473         .div_base       = 0,
 474         .has_tint_cstat = true,
 475         .tclk_mask      = (1 << 7) | (1 << 6) | (1 << 5),
 476 };
 477
 478 static int __init s3c64xx_pwm_clocksource_init(struct device_node *np)
 479 {
 480         return samsung_pwm_alloc(np, &s3c64xx_variant);
 481 }
 482 TIMER_OF_DECLARE(s3c6400_pwm, "samsung,s3c6400-pwm", s3c64xx_pwm_clocksource_init);
 483
 484 static const struct samsung_pwm_variant s5p64x0_variant = {
 485         .bits           = 32,
 486         .div_base       = 0,
 487         .has_tint_cstat = true,
 488         .tclk_mask      = 0,
 489 };
 490
 491 static int __init s5p64x0_pwm_clocksource_init(struct device_node *np)
 492 {
 493         return samsung_pwm_alloc(np, &s5p64x0_variant);
 494 }
 495 TIMER_OF_DECLARE(s5p6440_pwm, "samsung,s5p6440-pwm", s5p64x0_pwm_clocksource_init);
 496
 497 static const struct samsung_pwm_variant s5p_variant = {
 498         .bits           = 32,
 499         .div_base       = 0,
 500         .has_tint_cstat = true,
 501         .tclk_mask      = (1 << 5),
 502 };
 503
 504 static int __init s5p_pwm_clocksource_init(struct device_node *np)
 505 {
 506         return samsung_pwm_alloc(np, &s5p_variant);
 507 }
 508 TIMER_OF_DECLARE(s5pc100_pwm, "samsung,s5pc100-pwm", s5p_pwm_clocksource_init);
 509 #endif