drivers/clocksource/clps711x-timer.c

   1 /*
   2  *  Cirrus Logic CLPS711X clocksource driver
   3  *
   4  *  Copyright (C) 2014 Alexander Shiyan <shc_work@mail.ru>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (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/interrupt.h>
  16 #include <linux/io.h>
  17 #include <linux/of_address.h>
  18 #include <linux/of_irq.h>
  19 #include <linux/sched_clock.h>
  20 #include <linux/slab.h>
  21
  22 enum {
  23         CLPS711X_CLKSRC_CLOCKSOURCE,
  24         CLPS711X_CLKSRC_CLOCKEVENT,
  25 };
  26
  27 static void __iomem *tcd;
  28
  29 static u64 notrace clps711x_sched_clock_read(void)
  30 {
  31         return ~readw(tcd);
  32 }
  33
  34 static void __init clps711x_clksrc_init(struct clk *clock, void __iomem *base)
  35 {
  36         unsigned long rate = clk_get_rate(clock);
  37
  38         tcd = base;
  39
  40         clocksource_mmio_init(tcd, "clps711x-clocksource", rate, 300, 16,
  41                               clocksource_mmio_readw_down);
  42
  43         sched_clock_register(clps711x_sched_clock_read, 16, rate);
  44 }
  45
  46 static irqreturn_t clps711x_timer_interrupt(int irq, void *dev_id)
  47 {
  48         struct clock_event_device *evt = dev_id;
  49
  50         evt->event_handler(evt);
  51
  52         return IRQ_HANDLED;
  53 }
  54
  55 static int __init _clps711x_clkevt_init(struct clk *clock, void __iomem *base,
  56                                         unsigned int irq)
  57 {
  58         struct clock_event_device *clkevt;
  59         unsigned long rate;
  60
  61         clkevt = kzalloc(sizeof(*clkevt), GFP_KERNEL);
  62         if (!clkevt)
  63                 return -ENOMEM;
  64
  65         rate = clk_get_rate(clock);
  66
  67         /* Set Timer prescaler */
  68         writew(DIV_ROUND_CLOSEST(rate, HZ), base);
  69
  70         clkevt->name = "clps711x-clockevent";
  71         clkevt->rating = 300;
  72         clkevt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_C3STOP;
  73         clkevt->cpumask = cpumask_of(0);
  74         clockevents_config_and_register(clkevt, HZ, 0, 0);
  75
  76         return request_irq(irq, clps711x_timer_interrupt, IRQF_TIMER,
  77                            "clps711x-timer", clkevt);
  78 }
  79
  80 static int __init clps711x_timer_init(struct device_node *np)
  81 {
  82         unsigned int irq = irq_of_parse_and_map(np, 0);
  83         struct clk *clock = of_clk_get(np, 0);
  84         void __iomem *base = of_iomap(np, 0);
  85
  86         if (!base)
  87                 return -ENOMEM;
  88         if (!irq)
  89                 return -EINVAL;
  90         if (IS_ERR(clock))
  91                 return PTR_ERR(clock);
  92
  93         switch (of_alias_get_id(np, "timer")) {
  94         case CLPS711X_CLKSRC_CLOCKSOURCE:
  95                 clps711x_clksrc_init(clock, base);
  96                 break;
  97         case CLPS711X_CLKSRC_CLOCKEVENT:
  98                 return _clps711x_clkevt_init(clock, base, irq);
  99         default:
 100                 return -EINVAL;
 101         }
 102
 103         return 0;
 104 }
 105 TIMER_OF_DECLARE(clps711x, "cirrus,ep7209-timer", clps711x_timer_init);