drivers/clocksource/timer-fsl-ftm.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Freescale FlexTimer Module (FTM) timer driver.
   4  *
   5  * Copyright 2014 Freescale Semiconductor, Inc.
   6  */
   7
   8 #include <linux/clk.h>
   9 #include <linux/clockchips.h>
  10 #include <linux/clocksource.h>
  11 #include <linux/err.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/io.h>
  14 #include <linux/of_address.h>
  15 #include <linux/of_irq.h>
  16 #include <linux/sched_clock.h>
  17 #include <linux/slab.h>
  18 #include <linux/fsl/ftm.h>
  19
  20 #define FTM_SC_CLK(c)   ((c) << FTM_SC_CLK_MASK_SHIFT)
  21
  22 struct ftm_clock_device {
  23         void __iomem *clksrc_base;
  24         void __iomem *clkevt_base;
  25         unsigned long periodic_cyc;
  26         unsigned long ps;
  27         bool big_endian;
  28 };
  29
  30 static struct ftm_clock_device *priv;
  31
  32 static inline u32 ftm_readl(void __iomem *addr)
  33 {
  34         if (priv->big_endian)
  35                 return ioread32be(addr);
  36         else
  37                 return ioread32(addr);
  38 }
  39
  40 static inline void ftm_writel(u32 val, void __iomem *addr)
  41 {
  42         if (priv->big_endian)
  43                 iowrite32be(val, addr);
  44         else
  45                 iowrite32(val, addr);
  46 }
  47
  48 static inline void ftm_counter_enable(void __iomem *base)
  49 {
  50         u32 val;
  51
  52         /* select and enable counter clock source */
  53         val = ftm_readl(base + FTM_SC);
  54         val &= ~(FTM_SC_PS_MASK | FTM_SC_CLK_MASK);
  55         val |= priv->ps | FTM_SC_CLK(1);
  56         ftm_writel(val, base + FTM_SC);
  57 }
  58
  59 static inline void ftm_counter_disable(void __iomem *base)
  60 {
  61         u32 val;
  62
  63         /* disable counter clock source */
  64         val = ftm_readl(base + FTM_SC);
  65         val &= ~(FTM_SC_PS_MASK | FTM_SC_CLK_MASK);
  66         ftm_writel(val, base + FTM_SC);
  67 }
  68
  69 static inline void ftm_irq_acknowledge(void __iomem *base)
  70 {
  71         u32 val;
  72
  73         val = ftm_readl(base + FTM_SC);
  74         val &= ~FTM_SC_TOF;
  75         ftm_writel(val, base + FTM_SC);
  76 }
  77
  78 static inline void ftm_irq_enable(void __iomem *base)
  79 {
  80         u32 val;
  81
  82         val = ftm_readl(base + FTM_SC);
  83         val |= FTM_SC_TOIE;
  84         ftm_writel(val, base + FTM_SC);
  85 }
  86
  87 static inline void ftm_irq_disable(void __iomem *base)
  88 {
  89         u32 val;
  90
  91         val = ftm_readl(base + FTM_SC);
  92         val &= ~FTM_SC_TOIE;
  93         ftm_writel(val, base + FTM_SC);
  94 }
  95
  96 static inline void ftm_reset_counter(void __iomem *base)
  97 {
  98         /*
  99          * The CNT register contains the FTM counter value.
 100          * Reset clears the CNT register. Writing any value to COUNT
 101          * updates the counter with its initial value, CNTIN.
 102          */
 103         ftm_writel(0x00, base + FTM_CNT);
 104 }
 105
 106 static u64 notrace ftm_read_sched_clock(void)
 107 {
 108         return ftm_readl(priv->clksrc_base + FTM_CNT);
 109 }
 110
 111 static int ftm_set_next_event(unsigned long delta,
 112                                 struct clock_event_device *unused)
 113 {
 114         /*
 115          * The CNNIN and MOD are all double buffer registers, writing
 116          * to the MOD register latches the value into a buffer. The MOD
 117          * register is updated with the value of its write buffer with
 118          * the following scenario:
 119          * a, the counter source clock is disabled.
 120          */
 121         ftm_counter_disable(priv->clkevt_base);
 122
 123         /* Force the value of CNTIN to be loaded into the FTM counter */
 124         ftm_reset_counter(priv->clkevt_base);
 125
 126         /*
 127          * The counter increments until the value of MOD is reached,
 128          * at which point the counter is reloaded with the value of CNTIN.
 129          * The TOF (the overflow flag) bit is set when the FTM counter
 130          * changes from MOD to CNTIN. So we should using the delta - 1.
 131          */
 132         ftm_writel(delta - 1, priv->clkevt_base + FTM_MOD);
 133
 134         ftm_counter_enable(priv->clkevt_base);
 135
 136         ftm_irq_enable(priv->clkevt_base);
 137
 138         return 0;
 139 }
 140
 141 static int ftm_set_oneshot(struct clock_event_device *evt)
 142 {
 143         ftm_counter_disable(priv->clkevt_base);
 144         return 0;
 145 }
 146
 147 static int ftm_set_periodic(struct clock_event_device *evt)
 148 {
 149         ftm_set_next_event(priv->periodic_cyc, evt);
 150         return 0;
 151 }
 152
 153 static irqreturn_t ftm_evt_interrupt(int irq, void *dev_id)
 154 {
 155         struct clock_event_device *evt = dev_id;
 156
 157         ftm_irq_acknowledge(priv->clkevt_base);
 158
 159         if (likely(clockevent_state_oneshot(evt))) {
 160                 ftm_irq_disable(priv->clkevt_base);
 161                 ftm_counter_disable(priv->clkevt_base);
 162         }
 163
 164         evt->event_handler(evt);
 165
 166         return IRQ_HANDLED;
 167 }
 168
 169 static struct clock_event_device ftm_clockevent = {
 170         .name                   = "Freescale ftm timer",
 171         .features               = CLOCK_EVT_FEAT_PERIODIC |
 172                                   CLOCK_EVT_FEAT_ONESHOT,
 173         .set_state_periodic     = ftm_set_periodic,
 174         .set_state_oneshot      = ftm_set_oneshot,
 175         .set_next_event         = ftm_set_next_event,
 176         .rating                 = 300,
 177 };
 178
 179 static int __init ftm_clockevent_init(unsigned long freq, int irq)
 180 {
 181         int err;
 182
 183         ftm_writel(0x00, priv->clkevt_base + FTM_CNTIN);
 184         ftm_writel(~0u, priv->clkevt_base + FTM_MOD);
 185
 186         ftm_reset_counter(priv->clkevt_base);
 187
 188         err = request_irq(irq, ftm_evt_interrupt, IRQF_TIMER | IRQF_IRQPOLL,
 189                           "Freescale ftm timer", &ftm_clockevent);
 190         if (err) {
 191                 pr_err("ftm: setup irq failed: %d\n", err);
 192                 return err;
 193         }
 194
 195         ftm_clockevent.cpumask = cpumask_of(0);
 196         ftm_clockevent.irq = irq;
 197
 198         clockevents_config_and_register(&ftm_clockevent,
 199                                         freq / (1 << priv->ps),
 200                                         1, 0xffff);
 201
 202         ftm_counter_enable(priv->clkevt_base);
 203
 204         return 0;
 205 }
 206
 207 static int __init ftm_clocksource_init(unsigned long freq)
 208 {
 209         int err;
 210
 211         ftm_writel(0x00, priv->clksrc_base + FTM_CNTIN);
 212         ftm_writel(~0u, priv->clksrc_base + FTM_MOD);
 213
 214         ftm_reset_counter(priv->clksrc_base);
 215
 216         sched_clock_register(ftm_read_sched_clock, 16, freq / (1 << priv->ps));
 217         err = clocksource_mmio_init(priv->clksrc_base + FTM_CNT, "fsl-ftm",
 218                                     freq / (1 << priv->ps), 300, 16,
 219                                     clocksource_mmio_readl_up);
 220         if (err) {
 221                 pr_err("ftm: init clock source mmio failed: %d\n", err);
 222                 return err;
 223         }
 224
 225         ftm_counter_enable(priv->clksrc_base);
 226
 227         return 0;
 228 }
 229
 230 static int __init __ftm_clk_init(struct device_node *np, char *cnt_name,
 231                                  char *ftm_name)
 232 {
 233         struct clk *clk;
 234         int err;
 235
 236         clk = of_clk_get_by_name(np, cnt_name);
 237         if (IS_ERR(clk)) {
 238                 pr_err("ftm: Cannot get \"%s\": %ld\n", cnt_name, PTR_ERR(clk));
 239                 return PTR_ERR(clk);
 240         }
 241         err = clk_prepare_enable(clk);
 242         if (err) {
 243                 pr_err("ftm: clock failed to prepare+enable \"%s\": %d\n",
 244                         cnt_name, err);
 245                 return err;
 246         }
 247
 248         clk = of_clk_get_by_name(np, ftm_name);
 249         if (IS_ERR(clk)) {
 250                 pr_err("ftm: Cannot get \"%s\": %ld\n", ftm_name, PTR_ERR(clk));
 251                 return PTR_ERR(clk);
 252         }
 253         err = clk_prepare_enable(clk);
 254         if (err)
 255                 pr_err("ftm: clock failed to prepare+enable \"%s\": %d\n",
 256                         ftm_name, err);
 257
 258         return clk_get_rate(clk);
 259 }
 260
 261 static unsigned long __init ftm_clk_init(struct device_node *np)
 262 {
 263         long freq;
 264
 265         freq = __ftm_clk_init(np, "ftm-evt-counter-en", "ftm-evt");
 266         if (freq <= 0)
 267                 return 0;
 268
 269         freq = __ftm_clk_init(np, "ftm-src-counter-en", "ftm-src");
 270         if (freq <= 0)
 271                 return 0;
 272
 273         return freq;
 274 }
 275
 276 static int __init ftm_calc_closest_round_cyc(unsigned long freq)
 277 {
 278         priv->ps = 0;
 279
 280         /* The counter register is only using the lower 16 bits, and
 281          * if the 'freq' value is to big here, then the periodic_cyc
 282          * may exceed 0xFFFF.
 283          */
 284         do {
 285                 priv->periodic_cyc = DIV_ROUND_CLOSEST(freq,
 286                                                 HZ * (1 << priv->ps++));
 287         } while (priv->periodic_cyc > 0xFFFF);
 288
 289         if (priv->ps > FTM_PS_MAX) {
 290                 pr_err("ftm: the prescaler is %lu > %d\n",
 291                                 priv->ps, FTM_PS_MAX);
 292                 return -EINVAL;
 293         }
 294
 295         return 0;
 296 }
 297
 298 static int __init ftm_timer_init(struct device_node *np)
 299 {
 300         unsigned long freq;
 301         int ret, irq;
 302
 303         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 304         if (!priv)
 305                 return -ENOMEM;
 306
 307         ret = -ENXIO;
 308         priv->clkevt_base = of_iomap(np, 0);
 309         if (!priv->clkevt_base) {
 310                 pr_err("ftm: unable to map event timer registers\n");
 311                 goto err_clkevt;
 312         }
 313
 314         priv->clksrc_base = of_iomap(np, 1);
 315         if (!priv->clksrc_base) {
 316                 pr_err("ftm: unable to map source timer registers\n");
 317                 goto err_clksrc;
 318         }
 319
 320         ret = -EINVAL;
 321         irq = irq_of_parse_and_map(np, 0);
 322         if (irq <= 0) {
 323                 pr_err("ftm: unable to get IRQ from DT, %d\n", irq);
 324                 goto err;
 325         }
 326
 327         priv->big_endian = of_property_read_bool(np, "big-endian");
 328
 329         freq = ftm_clk_init(np);
 330         if (!freq)
 331                 goto err;
 332
 333         ret = ftm_calc_closest_round_cyc(freq);
 334         if (ret)
 335                 goto err;
 336
 337         ret = ftm_clocksource_init(freq);
 338         if (ret)
 339                 goto err;
 340
 341         ret = ftm_clockevent_init(freq, irq);
 342         if (ret)
 343                 goto err;
 344
 345         return 0;
 346
 347 err:
 348         iounmap(priv->clksrc_base);
 349 err_clksrc:
 350         iounmap(priv->clkevt_base);
 351 err_clkevt:
 352         kfree(priv);
 353         return ret;
 354 }
 355 TIMER_OF_DECLARE(flextimer, "fsl,ftm-timer", ftm_timer_init);