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 "\n", __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");
 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");
 261                 return -EBUSY;
 262         }
 263
 264         base = ioremap(timer_cfg->reg.start, resource_size(&timer_cfg->reg));
 265         if (!base) {
 266                 pr_err("Unable to map the register range");
 267                 return -ENOMEM;
 268         }
 269
 270         davinci_timer_init(base);
 271         tick_rate = clk_get_rate(clk);
 272
 273         clockevent = kzalloc(sizeof(*clockevent), GFP_KERNEL | __GFP_NOFAIL);
 274         if (!clockevent) {
 275                 pr_err("Error allocating memory for clockevent data");
 276                 return -ENOMEM;
 277         }
 278
 279         clockevent->dev.name = "tim12";
 280         clockevent->dev.features = CLOCK_EVT_FEAT_ONESHOT;
 281         clockevent->dev.cpumask = cpumask_of(0);
 282         clockevent->base = base;
 283
 284         if (timer_cfg->cmp_off) {
 285                 clockevent->cmp_off = timer_cfg->cmp_off;
 286                 clockevent->dev.set_next_event =
 287                                 davinci_clockevent_set_next_event_cmp;
 288         } else {
 289                 clockevent->dev.set_next_event =
 290                                 davinci_clockevent_set_next_event_std;
 291                 clockevent->dev.set_state_oneshot =
 292                                 davinci_clockevent_set_oneshot;
 293                 clockevent->dev.set_state_shutdown =
 294                                 davinci_clockevent_shutdown;
 295         }
 296
 297         rv = request_irq(timer_cfg->irq[DAVINCI_TIMER_CLOCKEVENT_IRQ].start,
 298                          davinci_timer_irq_timer, IRQF_TIMER,
 299                          "clockevent/tim12", clockevent);
 300         if (rv) {
 301                 pr_err("Unable to request the clockevent interrupt");
 302                 return rv;
 303         }
 304
 305         davinci_clocksource.dev.rating = 300;
 306         davinci_clocksource.dev.read = davinci_clocksource_read;
 307         davinci_clocksource.dev.mask =
 308                         CLOCKSOURCE_MASK(DAVINCI_TIMER_CLKSRC_BITS);
 309         davinci_clocksource.dev.flags = CLOCK_SOURCE_IS_CONTINUOUS;
 310         davinci_clocksource.base = base;
 311
 312         if (timer_cfg->cmp_off) {
 313                 davinci_clocksource.dev.name = "tim12";
 314                 davinci_clocksource.tim_off = DAVINCI_TIMER_REG_TIM12;
 315                 davinci_clocksource_init_tim12(base);
 316         } else {
 317                 davinci_clocksource.dev.name = "tim34";
 318                 davinci_clocksource.tim_off = DAVINCI_TIMER_REG_TIM34;
 319                 davinci_clocksource_init_tim34(base);
 320         }
 321
 322         clockevents_config_and_register(&clockevent->dev, tick_rate,
 323                                         DAVINCI_TIMER_MIN_DELTA,
 324                                         DAVINCI_TIMER_MAX_DELTA);
 325
 326         rv = clocksource_register_hz(&davinci_clocksource.dev, tick_rate);
 327         if (rv) {
 328                 pr_err("Unable to register clocksource");
 329                 return rv;
 330         }
 331
 332         sched_clock_register(davinci_timer_read_sched_clock,
 333                              DAVINCI_TIMER_CLKSRC_BITS, tick_rate);
 334
 335         return 0;
 336 }
 337
 338 static int __init of_davinci_timer_register(struct device_node *np)
 339 {
 340         struct davinci_timer_cfg timer_cfg = { };
 341         struct clk *clk;
 342         int rv;
 343
 344         rv = of_address_to_resource(np, 0, &timer_cfg.reg);
 345         if (rv) {
 346                 pr_err("Unable to get the register range for timer");
 347                 return rv;
 348         }
 349
 350         rv = of_irq_to_resource_table(np, timer_cfg.irq,
 351                                       DAVINCI_TIMER_NUM_IRQS);
 352         if (rv != DAVINCI_TIMER_NUM_IRQS) {
 353                 pr_err("Unable to get the interrupts for timer");
 354                 return rv;
 355         }
 356
 357         clk = of_clk_get(np, 0);
 358         if (IS_ERR(clk)) {
 359                 pr_err("Unable to get the timer clock");
 360                 return PTR_ERR(clk);
 361         }
 362
 363         rv = davinci_timer_register(clk, &timer_cfg);
 364         if (rv)
 365                 clk_put(clk);
 366
 367         return rv;
 368 }
 369 TIMER_OF_DECLARE(davinci_timer, "ti,da830-timer", of_davinci_timer_register);