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 void clps711x_clockevent_set_mode(enum clock_event_mode mode,
  65                                          struct clock_event_device *evt)
  66 {
  67 }
  68
  69 static int __init _clps711x_clkevt_init(struct clk *clock, void __iomem *base,
  70                                         unsigned int irq)
  71 {
  72         struct clock_event_device *clkevt;
  73         unsigned long rate;
  74
  75         if (!irq)
  76                 return -EINVAL;
  77         if (!base)
  78                 return -ENOMEM;
  79         if (IS_ERR(clock))
  80                 return PTR_ERR(clock);
  81
  82         clkevt = kzalloc(sizeof(*clkevt), GFP_KERNEL);
  83         if (!clkevt)
  84                 return -ENOMEM;
  85
  86         rate = clk_get_rate(clock);
  87
  88         /* Set Timer prescaler */
  89         writew(DIV_ROUND_CLOSEST(rate, HZ), base);
  90
  91         clkevt->name = "clps711x-clockevent";
  92         clkevt->rating = 300;
  93         clkevt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_C3STOP;
  94         clkevt->set_mode = clps711x_clockevent_set_mode;
  95         clkevt->cpumask = cpumask_of(0);
  96         clockevents_config_and_register(clkevt, HZ, 0, 0);
  97
  98         return request_irq(irq, clps711x_timer_interrupt, IRQF_TIMER,
  99                            "clps711x-timer", clkevt);
 100 }
 101
 102 void __init clps711x_clksrc_init(void __iomem *tc1_base, void __iomem *tc2_base,
 103                                  unsigned int irq)
 104 {
 105         struct clk *tc1 = clk_get_sys("clps711x-timer.0", NULL);
 106         struct clk *tc2 = clk_get_sys("clps711x-timer.1", NULL);
 107
 108         BUG_ON(_clps711x_clksrc_init(tc1, tc1_base));
 109         BUG_ON(_clps711x_clkevt_init(tc2, tc2_base, irq));
 110 }
 111
 112 #ifdef CONFIG_CLKSRC_OF
 113 static void __init clps711x_timer_init(struct device_node *np)
 114 {
 115         unsigned int irq = irq_of_parse_and_map(np, 0);
 116         struct clk *clock = of_clk_get(np, 0);
 117         void __iomem *base = of_iomap(np, 0);
 118
 119         switch (of_alias_get_id(np, "timer")) {
 120         case CLPS711X_CLKSRC_CLOCKSOURCE:
 121                 BUG_ON(_clps711x_clksrc_init(clock, base));
 122                 break;
 123         case CLPS711X_CLKSRC_CLOCKEVENT:
 124                 BUG_ON(_clps711x_clkevt_init(clock, base, irq));
 125                 break;
 126         default:
 127                 break;
 128         }
 129 }
 130 CLOCKSOURCE_OF_DECLARE(clps711x, "cirrus,clps711x-timer", clps711x_timer_init);
 131 #endif