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 void __init tango_clocksource_init(struct device_node *np)
  23 {
  24         struct clk *clk;
  25         int xtal_freq, ret;
  26
  27         xtal_in_cnt = of_iomap(np, 0);
  28         if (xtal_in_cnt == NULL) {
  29                 pr_err("%s: invalid address\n", np->full_name);
  30                 return;
  31         }
  32
  33         clk = of_clk_get(np, 0);
  34         if (IS_ERR(clk)) {
  35                 pr_err("%s: invalid clock\n", np->full_name);
  36                 return;
  37         }
  38
  39         xtal_freq = clk_get_rate(clk);
  40         delay_timer.freq = xtal_freq;
  41         delay_timer.read_current_timer = read_xtal_counter;
  42
  43         ret = clocksource_mmio_init(xtal_in_cnt, "tango-xtal", xtal_freq, 350,
  44                                     32, clocksource_mmio_readl_up);
  45         if (ret) {
  46                 pr_err("%s: registration failed\n", np->full_name);
  47                 return;
  48         }
  49
  50         sched_clock_register(read_sched_clock, 32, xtal_freq);
  51         register_current_timer_delay(&delay_timer);
  52 }
  53
  54 CLOCKSOURCE_OF_DECLARE(tango, "sigma,tick-counter", tango_clocksource_init);