drivers/clocksource/tango_xtal.c

   1 #include <linux/clocksource.h>
   2 #include <linux/sched_clock.h>
   3 #include <linux/of_address.h>
   4 #include <linux/printk.h>
   5 #include <linux/delay.h>
   6 #include <linux/init.h>
   7 #include <linux/clk.h>
   8
   9 static void __iomem *xtal_in_cnt;
  10 static struct delay_timer delay_timer;
  11
  12 static unsigned long notrace read_xtal_counter(void)
  13 {
  14         return readl_relaxed(xtal_in_cnt);
  15 }
  16
  17 static u64 notrace read_sched_clock(void)
  18 {
  19         return read_xtal_counter();
  20 }
  21
  22 static cycle_t read_clocksource(struct clocksource *cs)
  23 {
  24         return read_xtal_counter();
  25 }
  26
  27 static struct clocksource tango_xtal = {
  28         .name   = "tango-xtal",
  29         .rating = 350,
  30         .read   = read_clocksource,
  31         .mask   = CLOCKSOURCE_MASK(32),
  32         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
  33 };
  34
  35 static void __init tango_clocksource_init(struct device_node *np)
  36 {
  37         struct clk *clk;
  38         int xtal_freq, ret;
  39
  40         xtal_in_cnt = of_iomap(np, 0);
  41         if (xtal_in_cnt == NULL) {
  42                 pr_err("%s: invalid address\n", np->full_name);
  43                 return;
  44         }
  45
  46         clk = of_clk_get(np, 0);
  47         if (IS_ERR(clk)) {
  48                 pr_err("%s: invalid clock\n", np->full_name);
  49                 return;
  50         }
  51
  52         xtal_freq = clk_get_rate(clk);
  53         delay_timer.freq = xtal_freq;
  54         delay_timer.read_current_timer = read_xtal_counter;
  55
  56         ret = clocksource_register_hz(&tango_xtal, xtal_freq);
  57         if (ret != 0) {
  58                 pr_err("%s: registration failed\n", np->full_name);
  59                 return;
  60         }
  61
  62         sched_clock_register(read_sched_clock, 32, xtal_freq);
  63         register_current_timer_delay(&delay_timer);
  64 }
  65
  66 CLOCKSOURCE_OF_DECLARE(tango, "sigma,tick-counter", tango_clocksource_init);