drivers/clocksource/fsl_ftm_timer.c

   1 /*
   2  * Freescale FlexTimer Module (FTM) timer driver.
   3  *
   4  * Copyright 2014 Freescale Semiconductor, Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version 2
   9  * of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/clk.h>
  13 #include <linux/clockchips.h>
  14 #include <linux/clocksource.h>
  15 #include <linux/err.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/io.h>
  18 #include <linux/of_address.h>
  19 #include <linux/of_irq.h>
  20 #include <linux/sched_clock.h>
  21 #include <linux/slab.h>
  22
  23 #define FTM_SC          0x00
  24 #define FTM_SC_CLK_SHIFT        3
  25 #define FTM_SC_CLK_MASK (0x3 << FTM_SC_CLK_SHIFT)
  26 #define FTM_SC_CLK(c)   ((c) << FTM_SC_CLK_SHIFT)
  27 #define FTM_SC_PS_MASK  0x7
  28 #define FTM_SC_TOIE     BIT(6)
  29 #define FTM_SC_TOF      BIT(7)
  30
  31 #define FTM_CNT         0x04
  32 #define FTM_MOD         0x08
  33 #define FTM_CNTIN       0x4C
  34
  35 #define FTM_PS_MAX      7
  36
  37 struct ftm_clock_device {
  38         void __iomem *clksrc_base;
  39         void __iomem *clkevt_base;
  40         unsigned long periodic_cyc;
  41         unsigned long ps;
  42         bool big_endian;
  43 };
  44
  45 static struct ftm_clock_device *priv;
  46
  47 static inline u32 ftm_readl(void __iomem *addr)
  48 {
  49         if (priv->big_endian)
  50                 return ioread32be(addr);
  51         else
  52                 return ioread32(addr);
  53 }
  54
  55 static inline void ftm_writel(u32 val, void __iomem *addr)
  56 {
  57         if (priv->big_endian)
  58                 iowrite32be(val, addr);
  59         else
  60                 iowrite32(val, addr);
  61 }
  62
  63 static inline void ftm_counter_enable(void __iomem *base)
  64 {
  65         u32 val;
  66
  67         /* select and enable counter clock source */
  68         val = ftm_readl(base + FTM_SC);
  69         val &= ~(FTM_SC_PS_MASK | FTM_SC_CLK_MASK);
  70         val |= priv->ps | FTM_SC_CLK(1);
  71         ftm_writel(val, base + FTM_SC);
  72 }
  73
  74 static inline void ftm_counter_disable(void __iomem *base)
  75 {
  76         u32 val;
  77
  78         /* disable counter clock source */
  79         val = ftm_readl(base + FTM_SC);
  80         val &= ~(FTM_SC_PS_MASK | FTM_SC_CLK_MASK);
  81         ftm_writel(val, base + FTM_SC);
  82 }
  83
  84 static inline void ftm_irq_acknowledge(void __iomem *base)
  85 {
  86         u32 val;
  87
  88         val = ftm_readl(base + FTM_SC);
  89         val &= ~FTM_SC_TOF;
  90         ftm_writel(val, base + FTM_SC);
  91 }
  92
  93 static inline void ftm_irq_enable(void __iomem *base)
  94 {
  95         u32 val;
  96
  97         val = ftm_readl(base + FTM_SC);
  98         val |= FTM_SC_TOIE;
  99         ftm_writel(val, base + FTM_SC);
 100 }
 101
 102 static inline void ftm_irq_disable(void __iomem *base)
 103 {
 104         u32 val;
 105
 106         val = ftm_readl(base + FTM_SC);
 107         val &= ~FTM_SC_TOIE;
 108         ftm_writel(val, base + FTM_SC);
 109 }
 110
 111 static inline void ftm_reset_counter(void __iomem *base)
 112 {
 113         /*
 114          * The CNT register contains the FTM counter value.
 115          * Reset clears the CNT register. Writing any value to COUNT
 116          * updates the counter with its initial value, CNTIN.
 117          */
 118         ftm_writel(0x00, base + FTM_CNT);
 119 }
 120
 121 static u64 ftm_read_sched_clock(void)
 122 {
 123         return ftm_readl(priv->clksrc_base + FTM_CNT);
 124 }
 125
 126 static int ftm_set_next_event(unsigned long delta,
 127                                 struct clock_event_device *unused)
 128 {
 129         /*
 130          * The CNNIN and MOD are all double buffer registers, writing
 131          * to the MOD register latches the value into a buffer. The MOD
 132          * register is updated with the value of its write buffer with
 133          * the following scenario:
 134          * a, the counter source clock is diabled.
 135          */
 136         ftm_counter_disable(priv->clkevt_base);
 137
 138         /* Force the value of CNTIN to be loaded into the FTM counter */
 139         ftm_reset_counter(priv->clkevt_base);
 140
 141         /*
 142          * The counter increments until the value of MOD is reached,
 143          * at which point the counter is reloaded with the value of CNTIN.
 144          * The TOF (the overflow flag) bit is set when the FTM counter
 145          * changes from MOD to CNTIN. So we should using the delta - 1.
 146          */
 147         ftm_writel(delta - 1, priv->clkevt_base + FTM_MOD);
 148
 149         ftm_counter_enable(priv->clkevt_base);
 150
 151         ftm_irq_enable(priv->clkevt_base);
 152
 153         return 0;
 154 }
 155
 156 static void ftm_set_mode(enum clock_event_mode mode,
 157                                 struct clock_event_device *evt)
 158 {
 159         switch (mode) {
 160         case CLOCK_EVT_MODE_PERIODIC:
 161                 ftm_set_next_event(priv->periodic_cyc, evt);
 162                 break;
 163         case CLOCK_EVT_MODE_ONESHOT:
 164                 ftm_counter_disable(priv->clkevt_base);
 165                 break;
 166         default:
 167                 return;
 168         }
 169 }
 170
 171 static irqreturn_t ftm_evt_interrupt(int irq, void *dev_id)
 172 {
 173         struct clock_event_device *evt = dev_id;
 174
 175         ftm_irq_acknowledge(priv->clkevt_base);
 176
 177         if (likely(evt->mode == CLOCK_EVT_MODE_ONESHOT)) {
 178                 ftm_irq_disable(priv->clkevt_base);
 179                 ftm_counter_disable(priv->clkevt_base);
 180         }
 181
 182         evt->event_handler(evt);
 183
 184         return IRQ_HANDLED;
 185 }
 186
 187 static struct clock_event_device ftm_clockevent = {
 188         .name           = "Freescale ftm timer",
 189         .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 190         .set_mode       = ftm_set_mode,
 191         .set_next_event = ftm_set_next_event,
 192         .rating         = 300,
 193 };
 194
 195 static struct irqaction ftm_timer_irq = {
 196         .name           = "Freescale ftm timer",
 197         .flags          = IRQF_TIMER | IRQF_IRQPOLL,
 198         .handler        = ftm_evt_interrupt,
 199         .dev_id         = &ftm_clockevent,
 200 };
 201
 202 static int __init ftm_clockevent_init(unsigned long freq, int irq)
 203 {
 204         int err;
 205
 206         ftm_writel(0x00, priv->clkevt_base + FTM_CNTIN);
 207         ftm_writel(~0UL, priv->clkevt_base + FTM_MOD);
 208
 209         ftm_reset_counter(priv->clkevt_base);
 210
 211         err = setup_irq(irq, &ftm_timer_irq);
 212         if (err) {
 213                 pr_err("ftm: setup irq failed: %d\n", err);
 214                 return err;
 215         }
 216
 217         ftm_clockevent.cpumask = cpumask_of(0);
 218         ftm_clockevent.irq = irq;
 219
 220         clockevents_config_and_register(&ftm_clockevent,
 221                                         freq / (1 << priv->ps),
 222                                         1, 0xffff);
 223
 224         ftm_counter_enable(priv->clkevt_base);
 225
 226         return 0;
 227 }
 228
 229 static int __init ftm_clocksource_init(unsigned long freq)
 230 {
 231         int err;
 232
 233         ftm_writel(0x00, priv->clksrc_base + FTM_CNTIN);
 234         ftm_writel(~0UL, priv->clksrc_base + FTM_MOD);
 235
 236         ftm_reset_counter(priv->clksrc_base);
 237
 238         sched_clock_register(ftm_read_sched_clock, 16, freq / (1 << priv->ps));
 239         err = clocksource_mmio_init(priv->clksrc_base + FTM_CNT, "fsl-ftm",
 240                                     freq / (1 << priv->ps), 300, 16,
 241                                     clocksource_mmio_readl_up);
 242         if (err) {
 243                 pr_err("ftm: init clock source mmio failed: %d\n", err);
 244                 return err;
 245         }
 246
 247         ftm_counter_enable(priv->clksrc_base);
 248
 249         return 0;
 250 }
 251
 252 static int __init __ftm_clk_init(struct device_node *np, char *cnt_name,
 253                                  char *ftm_name)
 254 {
 255         struct clk *clk;
 256         int err;
 257
 258         clk = of_clk_get_by_name(np, cnt_name);
 259         if (IS_ERR(clk)) {
 260                 pr_err("ftm: Cannot get \"%s\": %ld\n", cnt_name, PTR_ERR(clk));
 261                 return PTR_ERR(clk);
 262         }
 263         err = clk_prepare_enable(clk);
 264         if (err) {
 265                 pr_err("ftm: clock failed to prepare+enable \"%s\": %d\n",
 266                         cnt_name, err);
 267                 return err;
 268         }
 269
 270         clk = of_clk_get_by_name(np, ftm_name);
 271         if (IS_ERR(clk)) {
 272                 pr_err("ftm: Cannot get \"%s\": %ld\n", ftm_name, PTR_ERR(clk));
 273                 return PTR_ERR(clk);
 274         }
 275         err = clk_prepare_enable(clk);
 276         if (err)
 277                 pr_err("ftm: clock failed to prepare+enable \"%s\": %d\n",
 278                         ftm_name, err);
 279
 280         return clk_get_rate(clk);
 281 }
 282
 283 static unsigned long __init ftm_clk_init(struct device_node *np)
 284 {
 285         unsigned long freq;
 286
 287         freq = __ftm_clk_init(np, "ftm-evt-counter-en", "ftm-evt");
 288         if (freq <= 0)
 289                 return 0;
 290
 291         freq = __ftm_clk_init(np, "ftm-src-counter-en", "ftm-src");
 292         if (freq <= 0)
 293                 return 0;
 294
 295         return freq;
 296 }
 297
 298 static int __init ftm_calc_closest_round_cyc(unsigned long freq)
 299 {
 300         priv->ps = 0;
 301
 302         /* The counter register is only using the lower 16 bits, and
 303          * if the 'freq' value is to big here, then the periodic_cyc
 304          * may exceed 0xFFFF.
 305          */
 306         do {
 307                 priv->periodic_cyc = DIV_ROUND_CLOSEST(freq,
 308                                                 HZ * (1 << priv->ps++));
 309         } while (priv->periodic_cyc > 0xFFFF);
 310
 311         if (priv->ps > FTM_PS_MAX) {
 312                 pr_err("ftm: the prescaler is %lu > %d\n",
 313                                 priv->ps, FTM_PS_MAX);
 314                 return -EINVAL;
 315         }
 316
 317         return 0;
 318 }
 319
 320 static void __init ftm_timer_init(struct device_node *np)
 321 {
 322         unsigned long freq;
 323         int irq;
 324
 325         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 326         if (!priv)
 327                 return;
 328
 329         priv->clkevt_base = of_iomap(np, 0);
 330         if (!priv->clkevt_base) {
 331                 pr_err("ftm: unable to map event timer registers\n");
 332                 goto err;
 333         }
 334
 335         priv->clksrc_base = of_iomap(np, 1);
 336         if (!priv->clksrc_base) {
 337                 pr_err("ftm: unable to map source timer registers\n");
 338                 goto err;
 339         }
 340
 341         irq = irq_of_parse_and_map(np, 0);
 342         if (irq <= 0) {
 343                 pr_err("ftm: unable to get IRQ from DT, %d\n", irq);
 344                 goto err;
 345         }
 346
 347         priv->big_endian = of_property_read_bool(np, "big-endian");
 348
 349         freq = ftm_clk_init(np);
 350         if (!freq)
 351                 goto err;
 352
 353         if (ftm_calc_closest_round_cyc(freq))
 354                 goto err;
 355
 356         if (ftm_clocksource_init(freq))
 357                 goto err;
 358
 359         if (ftm_clockevent_init(freq, irq))
 360                 goto err;
 361
 362         return;
 363
 364 err:
 365         kfree(priv);
 366 }
 367 CLOCKSOURCE_OF_DECLARE(flextimer, "fsl,ftm-timer", ftm_timer_init);