drivers/clocksource/tango_xtal.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/clocksource.h>
   3 #include <linux/sched_clock.h>
   4 #include <linux/of_address.h>
   5 #include <linux/printk.h>
   6 #include <linux/delay.h>
   7 #include <linux/init.h>
   8 #include <linux/clk.h>
   9
  10 static void __iomem *xtal_in_cnt;
  11 static struct delay_timer delay_timer;
  12
  13 static unsigned long notrace read_xtal_counter(void)
  14 {
  15         return readl_relaxed(xtal_in_cnt);
  16 }
  17
  18 static u64 notrace read_sched_clock(void)
  19 {
  20         return read_xtal_counter();
  21 }
  22
  23 static int __init tango_clocksource_init(struct device_node *np)
  24 {
  25         struct clk *clk;
  26         int xtal_freq, ret;
  27
  28         xtal_in_cnt = of_iomap(np, 0);
  29         if (xtal_in_cnt == NULL) {
  30                 pr_err("%pOF: invalid address\n", np);
  31                 return -ENXIO;
  32         }
  33
  34         clk = of_clk_get(np, 0);
  35         if (IS_ERR(clk)) {
  36                 pr_err("%pOF: invalid clock\n", np);
  37                 return PTR_ERR(clk);
  38         }
  39
  40         xtal_freq = clk_get_rate(clk);
  41         delay_timer.freq = xtal_freq;
  42         delay_timer.read_current_timer = read_xtal_counter;
  43
  44         ret = clocksource_mmio_init(xtal_in_cnt, "tango-xtal", xtal_freq, 350,
  45                                     32, clocksource_mmio_readl_up);
  46         if (ret) {
  47                 pr_err("%pOF: registration failed\n", np);
  48                 return ret;
  49         }
  50
  51         sched_clock_register(read_sched_clock, 32, xtal_freq);
  52         register_current_timer_delay(&delay_timer);
  53
  54         return 0;
  55 }
  56
  57 TIMER_OF_DECLARE(tango, "sigma,tick-counter", tango_clocksource_init);