drivers/clocksource/clps711x-timer.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Cirrus Logic CLPS711X clocksource driver
   4  *
   5  *  Copyright (C) 2014 Alexander Shiyan <shc_work@mail.ru>
   6  */
   7
   8 #include <linux/clk.h>
   9 #include <linux/clockchips.h>
  10 #include <linux/clocksource.h>
  11 #include <linux/interrupt.h>
  12 #include <linux/io.h>
  13 #include <linux/of_address.h>
  14 #include <linux/of_irq.h>
  15 #include <linux/sched_clock.h>
  16 #include <linux/slab.h>
  17
  18 enum {
  19         CLPS711X_CLKSRC_CLOCKSOURCE,
  20         CLPS711X_CLKSRC_CLOCKEVENT,
  21 };
  22
  23 static void __iomem *tcd;
  24
  25 static u64 notrace clps711x_sched_clock_read(void)
  26 {
  27         return ~readw(tcd);
  28 }
  29
  30 static void __init clps711x_clksrc_init(struct clk *clock, void __iomem *base)
  31 {
  32         unsigned long rate = clk_get_rate(clock);
  33
  34         tcd = base;
  35
  36         clocksource_mmio_init(tcd, "clps711x-clocksource", rate, 300, 16,
  37                               clocksource_mmio_readw_down);
  38
  39         sched_clock_register(clps711x_sched_clock_read, 16, rate);
  40 }
  41
  42 static irqreturn_t clps711x_timer_interrupt(int irq, void *dev_id)
  43 {
  44         struct clock_event_device *evt = dev_id;
  45
  46         evt->event_handler(evt);
  47
  48         return IRQ_HANDLED;
  49 }
  50
  51 static int __init _clps711x_clkevt_init(struct clk *clock, void __iomem *base,
  52                                         unsigned int irq)
  53 {
  54         struct clock_event_device *clkevt;
  55         unsigned long rate;
  56
  57         clkevt = kzalloc(sizeof(*clkevt), GFP_KERNEL);
  58         if (!clkevt)
  59                 return -ENOMEM;
  60
  61         rate = clk_get_rate(clock);
  62
  63         /* Set Timer prescaler */
  64         writew(DIV_ROUND_CLOSEST(rate, HZ), base);
  65
  66         clkevt->name = "clps711x-clockevent";
  67         clkevt->rating = 300;
  68         clkevt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_C3STOP;
  69         clkevt->cpumask = cpumask_of(0);
  70         clockevents_config_and_register(clkevt, HZ, 0, 0);
  71
  72         return request_irq(irq, clps711x_timer_interrupt, IRQF_TIMER,
  73                            "clps711x-timer", clkevt);
  74 }
  75
  76 static int __init clps711x_timer_init(struct device_node *np)
  77 {
  78         unsigned int irq = irq_of_parse_and_map(np, 0);
  79         struct clk *clock = of_clk_get(np, 0);
  80         void __iomem *base = of_iomap(np, 0);
  81
  82         if (!base)
  83                 return -ENOMEM;
  84         if (!irq)
  85                 return -EINVAL;
  86         if (IS_ERR(clock))
  87                 return PTR_ERR(clock);
  88
  89         switch (of_alias_get_id(np, "timer")) {
  90         case CLPS711X_CLKSRC_CLOCKSOURCE:
  91                 clps711x_clksrc_init(clock, base);
  92                 break;
  93         case CLPS711X_CLKSRC_CLOCKEVENT:
  94                 return _clps711x_clkevt_init(clock, base, irq);
  95         default:
  96                 return -EINVAL;
  97         }
  98
  99         return 0;
 100 }
 101 TIMER_OF_DECLARE(clps711x, "cirrus,ep7209-timer", clps711x_timer_init);