drivers/clocksource/timer-imx-sysctr.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 //
   3 // Copyright 2017-2019 NXP
   4
   5 #include <linux/interrupt.h>
   6 #include <linux/clockchips.h>
   7 #include <linux/of_address.h>
   8 #include <linux/of_irq.h>
   9
  10 #include "timer-of.h"
  11
  12 #define CMP_OFFSET      0x10000
  13
  14 #define CNTCV_LO        0x8
  15 #define CNTCV_HI        0xc
  16 #define CMPCV_LO        (CMP_OFFSET + 0x20)
  17 #define CMPCV_HI        (CMP_OFFSET + 0x24)
  18 #define CMPCR           (CMP_OFFSET + 0x2c)
  19
  20 #define SYS_CTR_EN              0x1
  21 #define SYS_CTR_IRQ_MASK        0x2
  22
  23 #define SYS_CTR_CLK_DIV         0x3
  24
  25 static void __iomem *sys_ctr_base;
  26 static u32 cmpcr;
  27
  28 static void sysctr_timer_enable(bool enable)
  29 {
  30         writel(enable ? cmpcr | SYS_CTR_EN : cmpcr, sys_ctr_base + CMPCR);
  31 }
  32
  33 static void sysctr_irq_acknowledge(void)
  34 {
  35         /*
  36          * clear the enable bit(EN =0) will clear
  37          * the status bit(ISTAT = 0), then the interrupt
  38          * signal will be negated(acknowledged).
  39          */
  40         sysctr_timer_enable(false);
  41 }
  42
  43 static inline u64 sysctr_read_counter(void)
  44 {
  45         u32 cnt_hi, tmp_hi, cnt_lo;
  46
  47         do {
  48                 cnt_hi = readl_relaxed(sys_ctr_base + CNTCV_HI);
  49                 cnt_lo = readl_relaxed(sys_ctr_base + CNTCV_LO);
  50                 tmp_hi = readl_relaxed(sys_ctr_base + CNTCV_HI);
  51         } while (tmp_hi != cnt_hi);
  52
  53         return  ((u64) cnt_hi << 32) | cnt_lo;
  54 }
  55
  56 static int sysctr_set_next_event(unsigned long delta,
  57                                  struct clock_event_device *evt)
  58 {
  59         u32 cmp_hi, cmp_lo;
  60         u64 next;
  61
  62         sysctr_timer_enable(false);
  63
  64         next = sysctr_read_counter();
  65
  66         next += delta;
  67
  68         cmp_hi = (next >> 32) & 0x00fffff;
  69         cmp_lo = next & 0xffffffff;
  70
  71         writel_relaxed(cmp_hi, sys_ctr_base + CMPCV_HI);
  72         writel_relaxed(cmp_lo, sys_ctr_base + CMPCV_LO);
  73
  74         sysctr_timer_enable(true);
  75
  76         return 0;
  77 }
  78
  79 static int sysctr_set_state_oneshot(struct clock_event_device *evt)
  80 {
  81         return 0;
  82 }
  83
  84 static int sysctr_set_state_shutdown(struct clock_event_device *evt)
  85 {
  86         sysctr_timer_enable(false);
  87
  88         return 0;
  89 }
  90
  91 static irqreturn_t sysctr_timer_interrupt(int irq, void *dev_id)
  92 {
  93         struct clock_event_device *evt = dev_id;
  94
  95         sysctr_irq_acknowledge();
  96
  97         evt->event_handler(evt);
  98
  99         return IRQ_HANDLED;
 100 }
 101
 102 static struct timer_of to_sysctr = {
 103         .flags = TIMER_OF_IRQ | TIMER_OF_CLOCK | TIMER_OF_BASE,
 104         .clkevt = {
 105                 .name                   = "i.MX system counter timer",
 106                 .features               = CLOCK_EVT_FEAT_ONESHOT |
 107                                                 CLOCK_EVT_FEAT_DYNIRQ,
 108                 .set_state_oneshot      = sysctr_set_state_oneshot,
 109                 .set_next_event         = sysctr_set_next_event,
 110                 .set_state_shutdown     = sysctr_set_state_shutdown,
 111                 .rating                 = 200,
 112         },
 113         .of_irq = {
 114                 .handler                = sysctr_timer_interrupt,
 115                 .flags                  = IRQF_TIMER | IRQF_IRQPOLL,
 116         },
 117         .of_clk = {
 118                 .name = "per",
 119         },
 120 };
 121
 122 static void __init sysctr_clockevent_init(void)
 123 {
 124         to_sysctr.clkevt.cpumask = cpumask_of(0);
 125
 126         clockevents_config_and_register(&to_sysctr.clkevt,
 127                                         timer_of_rate(&to_sysctr),
 128                                         0xff, 0x7fffffff);
 129 }
 130
 131 static int __init sysctr_timer_init(struct device_node *np)
 132 {
 133         int ret = 0;
 134
 135         ret = timer_of_init(np, &to_sysctr);
 136         if (ret)
 137                 return ret;
 138
 139         /* system counter clock is divided by 3 internally */
 140         to_sysctr.of_clk.rate /= SYS_CTR_CLK_DIV;
 141
 142         sys_ctr_base = timer_of_base(&to_sysctr);
 143         cmpcr = readl(sys_ctr_base + CMPCR);
 144         cmpcr &= ~SYS_CTR_EN;
 145
 146         sysctr_clockevent_init();
 147
 148         return 0;
 149 }
 150 TIMER_OF_DECLARE(sysctr_timer, "nxp,sysctr-timer", sysctr_timer_init);