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 int __init _clps711x_clksrc_init(struct clk *clock, void __iomem *base)
  35 {
  36         unsigned long rate;
  37
  38         if (!base)
  39                 return -ENOMEM;
  40         if (IS_ERR(clock))
  41                 return PTR_ERR(clock);
  42
  43         rate = clk_get_rate(clock);
  44
  45         tcd = base;
  46
  47         clocksource_mmio_init(tcd, "clps711x-clocksource", rate, 300, 16,
  48                               clocksource_mmio_readw_down);
  49
  50         sched_clock_register(clps711x_sched_clock_read, 16, rate);
  51
  52         return 0;
  53 }
  54
  55 static irqreturn_t clps711x_timer_interrupt(int irq, void *dev_id)
  56 {
  57         struct clock_event_device *evt = dev_id;
  58
  59         evt->event_handler(evt);
  60
  61         return IRQ_HANDLED;
  62 }
  63
  64 static int __init _clps711x_clkevt_init(struct clk *clock, void __iomem *base,
  65                                         unsigned int irq)
  66 {
  67         struct clock_event_device *clkevt;
  68         unsigned long rate;
  69
  70         if (!irq)
  71                 return -EINVAL;
  72         if (!base)
  73                 return -ENOMEM;
  74         if (IS_ERR(clock))
  75                 return PTR_ERR(clock);
  76
  77         clkevt = kzalloc(sizeof(*clkevt), GFP_KERNEL);
  78         if (!clkevt)
  79                 return -ENOMEM;
  80
  81         rate = clk_get_rate(clock);
  82
  83         /* Set Timer prescaler */
  84         writew(DIV_ROUND_CLOSEST(rate, HZ), base);
  85
  86         clkevt->name = "clps711x-clockevent";
  87         clkevt->rating = 300;
  88         clkevt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_C3STOP;
  89         clkevt->cpumask = cpumask_of(0);
  90         clockevents_config_and_register(clkevt, HZ, 0, 0);
  91
  92         return request_irq(irq, clps711x_timer_interrupt, IRQF_TIMER,
  93                            "clps711x-timer", clkevt);
  94 }
  95
  96 void __init clps711x_clksrc_init(void __iomem *tc1_base, void __iomem *tc2_base,
  97                                  unsigned int irq)
  98 {
  99         struct clk *tc1 = clk_get_sys("clps711x-timer.0", NULL);
 100         struct clk *tc2 = clk_get_sys("clps711x-timer.1", NULL);
 101
 102         BUG_ON(_clps711x_clksrc_init(tc1, tc1_base));
 103         BUG_ON(_clps711x_clkevt_init(tc2, tc2_base, irq));
 104 }
 105
 106 #ifdef CONFIG_TIMER_OF
 107 static int __init clps711x_timer_init(struct device_node *np)
 108 {
 109         unsigned int irq = irq_of_parse_and_map(np, 0);
 110         struct clk *clock = of_clk_get(np, 0);
 111         void __iomem *base = of_iomap(np, 0);
 112
 113         switch (of_alias_get_id(np, "timer")) {
 114         case CLPS711X_CLKSRC_CLOCKSOURCE:
 115                 return _clps711x_clksrc_init(clock, base);
 116         case CLPS711X_CLKSRC_CLOCKEVENT:
 117                 return _clps711x_clkevt_init(clock, base, irq);
 118         default:
 119                 return -EINVAL;
 120         }
 121 }
 122 TIMER_OF_DECLARE(clps711x, "cirrus,ep7209-timer", clps711x_timer_init);
 123 #endif