drivers/timer/arm_global_timer.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
   4  * Author(s): Patrice Chotard, <patrice.chotard@foss.st.com> for STMicroelectronics.
   5  *
   6  * ARM Cortext A9 global timer driver
   7  */
   8
   9 #include <common.h>
  10 #include <dm.h>
  11 #include <clk.h>
  12 #include <timer.h>
  13 #include <linux/err.h>
  14
  15 #include <asm/io.h>
  16 #include <asm/arch-armv7/globaltimer.h>
  17
  18 struct arm_global_timer_priv {
  19         struct globaltimer *global_timer;
  20 };
  21
  22 static u64 arm_global_timer_get_count(struct udevice *dev)
  23 {
  24         struct arm_global_timer_priv *priv = dev_get_priv(dev);
  25         struct globaltimer *global_timer = priv->global_timer;
  26         u32 low, high;
  27         u64 timer;
  28         u32 old = readl(&global_timer->cnt_h);
  29
  30         while (1) {
  31                 low = readl(&global_timer->cnt_l);
  32                 high = readl(&global_timer->cnt_h);
  33                 if (old == high)
  34                         break;
  35                 else
  36                         old = high;
  37         }
  38         timer = high;
  39         return (u64)((timer << 32) | low);
  40 }
  41
  42 static int arm_global_timer_probe(struct udevice *dev)
  43 {
  44         struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
  45         struct arm_global_timer_priv *priv = dev_get_priv(dev);
  46         struct clk clk;
  47         int err;
  48         ulong ret;
  49
  50         /* get arm global timer base address */
  51         priv->global_timer = (struct globaltimer *)dev_read_addr_ptr(dev);
  52         if (!priv->global_timer)
  53                 return -ENOENT;
  54
  55         err = clk_get_by_index(dev, 0, &clk);
  56         if (!err) {
  57                 ret = clk_get_rate(&clk);
  58                 if (IS_ERR_VALUE(ret))
  59                         return ret;
  60                 uc_priv->clock_rate = ret;
  61         } else {
  62                 uc_priv->clock_rate = CONFIG_SYS_HZ_CLOCK;
  63         }
  64
  65         /* init timer */
  66         writel(0x01, &priv->global_timer->ctl);
  67
  68         return 0;
  69 }
  70
  71 static const struct timer_ops arm_global_timer_ops = {
  72         .get_count = arm_global_timer_get_count,
  73 };
  74
  75 static const struct udevice_id arm_global_timer_ids[] = {
  76         { .compatible = "arm,cortex-a9-global-timer" },
  77         {}
  78 };
  79
  80 U_BOOT_DRIVER(arm_global_timer) = {
  81         .name = "arm_global_timer",
  82         .id = UCLASS_TIMER,
  83         .of_match = arm_global_timer_ids,
  84         .priv_auto      = sizeof(struct arm_global_timer_priv),
  85         .probe = arm_global_timer_probe,
  86         .ops = &arm_global_timer_ops,
  87 };