drivers/clocksource/timer-davinci.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * TI DaVinci clocksource driver
   4  *
   5  * Copyright (C) 2019 Texas Instruments
   6  * Author: Bartosz Golaszewski <bgolaszewski@baylibre.com>
   7  * (with tiny parts adopted from code by Kevin Hilman <khilman@baylibre.com>)
   8  */
   9
  10 #include <linux/clk.h>
  11 #include <linux/clockchips.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/kernel.h>
  14 #include <linux/of_address.h>
  15 #include <linux/of_irq.h>
  16 #include <linux/sched_clock.h>
  17
  18 #include <clocksource/timer-davinci.h>
  19
  20 #undef pr_fmt
  21 #define pr_fmt(fmt) "%s: " fmt, __func__
  22
  23 #define DAVINCI_TIMER_REG_TIM12                 0x10
  24 #define DAVINCI_TIMER_REG_TIM34                 0x14
  25 #define DAVINCI_TIMER_REG_PRD12                 0x18
  26 #define DAVINCI_TIMER_REG_PRD34                 0x1c
  27 #define DAVINCI_TIMER_REG_TCR                   0x20
  28 #define DAVINCI_TIMER_REG_TGCR                  0x24
  29
  30 #define DAVINCI_TIMER_TIMMODE_MASK              GENMASK(3, 2)
  31 #define DAVINCI_TIMER_RESET_MASK                GENMASK(1, 0)
  32 #define DAVINCI_TIMER_TIMMODE_32BIT_UNCHAINED   BIT(2)
  33 #define DAVINCI_TIMER_UNRESET                   GENMASK(1, 0)
  34
  35 #define DAVINCI_TIMER_ENAMODE_MASK              GENMASK(1, 0)
  36 #define DAVINCI_TIMER_ENAMODE_DISABLED          0x00
  37 #define DAVINCI_TIMER_ENAMODE_ONESHOT           BIT(0)
  38 #define DAVINCI_TIMER_ENAMODE_PERIODIC          BIT(1)
  39
  40 #define DAVINCI_TIMER_ENAMODE_SHIFT_TIM12       6
  41 #define DAVINCI_TIMER_ENAMODE_SHIFT_TIM34       22
  42
  43 #define DAVINCI_TIMER_MIN_DELTA                 0x01
  44 #define DAVINCI_TIMER_MAX_DELTA                 0xfffffffe
  45
  46 #define DAVINCI_TIMER_CLKSRC_BITS               32
  47
  48 #define DAVINCI_TIMER_TGCR_DEFAULT \
  49                 (DAVINCI_TIMER_TIMMODE_32BIT_UNCHAINED | DAVINCI_TIMER_UNRESET)
  50
  51 struct davinci_clockevent {
  52         struct clock_event_device dev;
  53         void __iomem *base;
  54         unsigned int cmp_off;
  55 };
  56
  57 /*
  58  * This must be globally accessible by davinci_timer_read_sched_clock(), so
  59  * let's keep it here.
  60  */
  61 static struct {
  62         struct clocksource dev;
  63         void __iomem *base;
  64         unsigned int tim_off;
  65 } davinci_clocksource;
  66
  67 static struct davinci_clockevent *
  68 to_davinci_clockevent(struct clock_event_device *clockevent)
  69 {
  70         return container_of(clockevent, struct davinci_clockevent, dev);
  71 }
  72
  73 static unsigned int
  74 davinci_clockevent_read(struct davinci_clockevent *clockevent,
  75                         unsigned int reg)
  76 {
  77         return readl_relaxed(clockevent->base + reg);
  78 }
  79
  80 static void davinci_clockevent_write(struct davinci_clockevent *clockevent,
  81                                      unsigned int reg, unsigned int val)
  82 {
  83         writel_relaxed(val, clockevent->base + reg);
  84 }
  85
  86 static void davinci_tim12_shutdown(void __iomem *base)
  87 {
  88         unsigned int tcr;
  89
  90         tcr = DAVINCI_TIMER_ENAMODE_DISABLED <<
  91                 DAVINCI_TIMER_ENAMODE_SHIFT_TIM12;
  92         /*
  93          * This function is only ever called if we're using both timer
  94          * halves. In this case TIM34 runs in periodic mode and we must
  95          * not modify it.
  96          */
  97         tcr |= DAVINCI_TIMER_ENAMODE_PERIODIC <<
  98                 DAVINCI_TIMER_ENAMODE_SHIFT_TIM34;
  99
 100         writel_relaxed(tcr, base + DAVINCI_TIMER_REG_TCR);
 101 }
 102
 103 static void davinci_tim12_set_oneshot(void __iomem *base)
 104 {
 105         unsigned int tcr;
 106
 107         tcr = DAVINCI_TIMER_ENAMODE_ONESHOT <<
 108                 DAVINCI_TIMER_ENAMODE_SHIFT_TIM12;
 109         /* Same as above. */
 110         tcr |= DAVINCI_TIMER_ENAMODE_PERIODIC <<
 111                 DAVINCI_TIMER_ENAMODE_SHIFT_TIM34;
 112
 113         writel_relaxed(tcr, base + DAVINCI_TIMER_REG_TCR);
 114 }
 115
 116 static int davinci_clockevent_shutdown(struct clock_event_device *dev)
 117 {
 118         struct davinci_clockevent *clockevent;
 119
 120         clockevent = to_davinci_clockevent(dev);
 121
 122         davinci_tim12_shutdown(clockevent->base);
 123
 124         return 0;
 125 }
 126
 127 static int davinci_clockevent_set_oneshot(struct clock_event_device *dev)
 128 {
 129         struct davinci_clockevent *clockevent = to_davinci_clockevent(dev);
 130
 131         davinci_clockevent_write(clockevent, DAVINCI_TIMER_REG_TIM12, 0x0);
 132
 133         davinci_tim12_set_oneshot(clockevent->base);
 134
 135         return 0;
 136 }
 137
 138 static int
 139 davinci_clockevent_set_next_event_std(unsigned long cycles,
 140                                       struct clock_event_device *dev)
 141 {
 142         struct davinci_clockevent *clockevent = to_davinci_clockevent(dev);
 143
 144         davinci_clockevent_shutdown(dev);
 145
 146         davinci_clockevent_write(clockevent, DAVINCI_TIMER_REG_TIM12, 0x0);
 147         davinci_clockevent_write(clockevent, DAVINCI_TIMER_REG_PRD12, cycles);
 148
 149         davinci_clockevent_set_oneshot(dev);
 150
 151         return 0;
 152 }
 153
 154 static int
 155 davinci_clockevent_set_next_event_cmp(unsigned long cycles,
 156                                       struct clock_event_device *dev)
 157 {
 158         struct davinci_clockevent *clockevent = to_davinci_clockevent(dev);
 159         unsigned int curr_time;
 160
 161         curr_time = davinci_clockevent_read(clockevent,
 162                                             DAVINCI_TIMER_REG_TIM12);
 163         davinci_clockevent_write(clockevent,
 164                                  clockevent->cmp_off, curr_time + cycles);
 165
 166         return 0;
 167 }
 168
 169 static irqreturn_t davinci_timer_irq_timer(int irq, void *data)
 170 {
 171         struct davinci_clockevent *clockevent = data;
 172
 173         if (!clockevent_state_oneshot(&clockevent->dev))
 174                 davinci_tim12_shutdown(clockevent->base);
 175
 176         clockevent->dev.event_handler(&clockevent->dev);
 177
 178         return IRQ_HANDLED;
 179 }
 180
 181 static u64 notrace davinci_timer_read_sched_clock(void)
 182 {
 183         return readl_relaxed(davinci_clocksource.base +
 184                              davinci_clocksource.tim_off);
 185 }
 186
 187 static u64 davinci_clocksource_read(struct clocksource *dev)
 188 {
 189         return davinci_timer_read_sched_clock();
 190 }
 191
 192 /*
 193  * Standard use-case: we're using tim12 for clockevent and tim34 for
 194  * clocksource. The default is making the former run in oneshot mode
 195  * and the latter in periodic mode.
 196  */
 197 static void davinci_clocksource_init_tim34(void __iomem *base)
 198 {
 199         int tcr;
 200
 201         tcr = DAVINCI_TIMER_ENAMODE_PERIODIC <<
 202                 DAVINCI_TIMER_ENAMODE_SHIFT_TIM34;
 203         tcr |= DAVINCI_TIMER_ENAMODE_ONESHOT <<
 204                 DAVINCI_TIMER_ENAMODE_SHIFT_TIM12;
 205
 206         writel_relaxed(0x0, base + DAVINCI_TIMER_REG_TIM34);
 207         writel_relaxed(UINT_MAX, base + DAVINCI_TIMER_REG_PRD34);
 208         writel_relaxed(tcr, base + DAVINCI_TIMER_REG_TCR);
 209 }
 210
 211 /*
 212  * Special use-case on da830: the DSP may use tim34. We're using tim12 for
 213  * both clocksource and clockevent. We set tim12 to periodic and don't touch
 214  * tim34.
 215  */
 216 static void davinci_clocksource_init_tim12(void __iomem *base)
 217 {
 218         unsigned int tcr;
 219
 220         tcr = DAVINCI_TIMER_ENAMODE_PERIODIC <<
 221                 DAVINCI_TIMER_ENAMODE_SHIFT_TIM12;
 222
 223         writel_relaxed(0x0, base + DAVINCI_TIMER_REG_TIM12);
 224         writel_relaxed(UINT_MAX, base + DAVINCI_TIMER_REG_PRD12);
 225         writel_relaxed(tcr, base + DAVINCI_TIMER_REG_TCR);
 226 }
 227
 228 static void davinci_timer_init(void __iomem *base)
 229 {
 230         /* Set clock to internal mode and disable it. */
 231         writel_relaxed(0x0, base + DAVINCI_TIMER_REG_TCR);
 232         /*
 233          * Reset both 32-bit timers, set no prescaler for timer 34, set the
 234          * timer to dual 32-bit unchained mode, unreset both 32-bit timers.
 235          */
 236         writel_relaxed(DAVINCI_TIMER_TGCR_DEFAULT,
 237                        base + DAVINCI_TIMER_REG_TGCR);
 238         /* Init both counters to zero. */
 239         writel_relaxed(0x0, base + DAVINCI_TIMER_REG_TIM12);
 240         writel_relaxed(0x0, base + DAVINCI_TIMER_REG_TIM34);
 241 }
 242
 243 int __init davinci_timer_register(struct clk *clk,
 244                                   const struct davinci_timer_cfg *timer_cfg)
 245 {
 246         struct davinci_clockevent *clockevent;
 247         unsigned int tick_rate;
 248         void __iomem *base;
 249         int rv;
 250
 251         rv = clk_prepare_enable(clk);
 252         if (rv) {
 253                 pr_err("Unable to prepare and enable the timer clock\n");
 254                 return rv;
 255         }
 256
 257         if (!request_mem_region(timer_cfg->reg.start,
 258                                 resource_size(&timer_cfg->reg),
 259                                 "davinci-timer")) {
 260                 pr_err("Unable to request memory region\n");
 261                 rv = -EBUSY;
 262                 goto exit_clk_disable;
 263         }
 264
 265         base = ioremap(timer_cfg->reg.start, resource_size(&timer_cfg->reg));
 266         if (!base) {
 267                 pr_err("Unable to map the register range\n");
 268                 rv = -ENOMEM;
 269                 goto exit_mem_region;
 270         }
 271
 272         davinci_timer_init(base);
 273         tick_rate = clk_get_rate(clk);
 274
 275         clockevent = kzalloc(sizeof(*clockevent), GFP_KERNEL);
 276         if (!clockevent) {
 277                 rv = -ENOMEM;
 278                 goto exit_iounmap_base;
 279         }
 280
 281         clockevent->dev.name = "tim12";
 282         clockevent->dev.features = CLOCK_EVT_FEAT_ONESHOT;
 283         clockevent->dev.cpumask = cpumask_of(0);
 284         clockevent->base = base;
 285
 286         if (timer_cfg->cmp_off) {
 287                 clockevent->cmp_off = timer_cfg->cmp_off;
 288                 clockevent->dev.set_next_event =
 289                                 davinci_clockevent_set_next_event_cmp;
 290         } else {
 291                 clockevent->dev.set_next_event =
 292                                 davinci_clockevent_set_next_event_std;
 293                 clockevent->dev.set_state_oneshot =
 294                                 davinci_clockevent_set_oneshot;
 295                 clockevent->dev.set_state_shutdown =
 296                                 davinci_clockevent_shutdown;
 297         }
 298
 299         rv = request_irq(timer_cfg->irq[DAVINCI_TIMER_CLOCKEVENT_IRQ].start,
 300                          davinci_timer_irq_timer, IRQF_TIMER,
 301                          "clockevent/tim12", clockevent);
 302         if (rv) {
 303                 pr_err("Unable to request the clockevent interrupt\n");
 304                 goto exit_free_clockevent;
 305         }
 306
 307         davinci_clocksource.dev.rating = 300;
 308         davinci_clocksource.dev.read = davinci_clocksource_read;
 309         davinci_clocksource.dev.mask =
 310                         CLOCKSOURCE_MASK(DAVINCI_TIMER_CLKSRC_BITS);
 311         davinci_clocksource.dev.flags = CLOCK_SOURCE_IS_CONTINUOUS;
 312         davinci_clocksource.base = base;
 313
 314         if (timer_cfg->cmp_off) {
 315                 davinci_clocksource.dev.name = "tim12";
 316                 davinci_clocksource.tim_off = DAVINCI_TIMER_REG_TIM12;
 317                 davinci_clocksource_init_tim12(base);
 318         } else {
 319                 davinci_clocksource.dev.name = "tim34";
 320                 davinci_clocksource.tim_off = DAVINCI_TIMER_REG_TIM34;
 321                 davinci_clocksource_init_tim34(base);
 322         }
 323
 324         clockevents_config_and_register(&clockevent->dev, tick_rate,
 325                                         DAVINCI_TIMER_MIN_DELTA,
 326                                         DAVINCI_TIMER_MAX_DELTA);
 327
 328         rv = clocksource_register_hz(&davinci_clocksource.dev, tick_rate);
 329         if (rv) {
 330                 pr_err("Unable to register clocksource\n");
 331                 goto exit_free_irq;
 332         }
 333
 334         sched_clock_register(davinci_timer_read_sched_clock,
 335                              DAVINCI_TIMER_CLKSRC_BITS, tick_rate);
 336
 337         return 0;
 338
 339 exit_free_irq:
 340         free_irq(timer_cfg->irq[DAVINCI_TIMER_CLOCKEVENT_IRQ].start,
 341                         clockevent);
 342 exit_free_clockevent:
 343         kfree(clockevent);
 344 exit_iounmap_base:
 345         iounmap(base);
 346 exit_mem_region:
 347         release_mem_region(timer_cfg->reg.start,
 348                            resource_size(&timer_cfg->reg));
 349 exit_clk_disable:
 350         clk_disable_unprepare(clk);
 351         return rv;
 352 }
 353
 354 static int __init of_davinci_timer_register(struct device_node *np)
 355 {
 356         struct davinci_timer_cfg timer_cfg = { };
 357         struct clk *clk;
 358         int rv;
 359
 360         rv = of_address_to_resource(np, 0, &timer_cfg.reg);
 361         if (rv) {
 362                 pr_err("Unable to get the register range for timer\n");
 363                 return rv;
 364         }
 365
 366         rv = of_irq_to_resource_table(np, timer_cfg.irq,
 367                                       DAVINCI_TIMER_NUM_IRQS);
 368         if (rv != DAVINCI_TIMER_NUM_IRQS) {
 369                 pr_err("Unable to get the interrupts for timer\n");
 370                 return rv;
 371         }
 372
 373         clk = of_clk_get(np, 0);
 374         if (IS_ERR(clk)) {
 375                 pr_err("Unable to get the timer clock\n");
 376                 return PTR_ERR(clk);
 377         }
 378
 379         rv = davinci_timer_register(clk, &timer_cfg);
 380         if (rv)
 381                 clk_put(clk);
 382
 383         return rv;
 384 }
 385 TIMER_OF_DECLARE(davinci_timer, "ti,da830-timer", of_davinci_timer_register);