LXR uboot/arch/arm/mach-zynq/timer.c

   1/*
   2 * Copyright (C) 2012 Michal Simek <monstr@monstr.eu>
   3 * Copyright (C) 2011-2012 Xilinx, Inc. All rights reserved.
   4 *
   5 * (C) Copyright 2008
   6 * Guennadi Liakhovetki, DENX Software Engineering, <lg@denx.de>
   7 *
   8 * (C) Copyright 2004
   9 * Philippe Robin, ARM Ltd. <philippe.robin@arm.com>
  10 *
  11 * (C) Copyright 2002-2004
  12 * Gary Jennejohn, DENX Software Engineering, <gj@denx.de>
  13 *
  14 * (C) Copyright 2003
  15 * Texas Instruments <www.ti.com>
  16 *
  17 * (C) Copyright 2002
  18 * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
  19 * Marius Groeger <mgroeger@sysgo.de>
  20 *
  21 * (C) Copyright 2002
  22 * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
  23 * Alex Zuepke <azu@sysgo.de>
  24 *
  25 * SPDX-License-Identifier:     GPL-2.0+
  26 */
  27
  28#include <common.h>
  29#include <div64.h>
  30#include <asm/io.h>
  31#include <asm/arch/hardware.h>
  32#include <asm/arch/clk.h>
  33
  34DECLARE_GLOBAL_DATA_PTR;
  35
  36struct scu_timer {
  37        u32 load; /* Timer Load Register */
  38        u32 counter; /* Timer Counter Register */
  39        u32 control; /* Timer Control Register */
  40};
  41
  42static struct scu_timer *timer_base =
  43                              (struct scu_timer *)ZYNQ_SCUTIMER_BASEADDR;
  44
  45#define SCUTIMER_CONTROL_PRESCALER_MASK 0x0000FF00 /* Prescaler */
  46#define SCUTIMER_CONTROL_PRESCALER_SHIFT        8
  47#define SCUTIMER_CONTROL_AUTO_RELOAD_MASK       0x00000002 /* Auto-reload */
  48#define SCUTIMER_CONTROL_ENABLE_MASK            0x00000001 /* Timer enable */
  49
  50#define TIMER_LOAD_VAL 0xFFFFFFFF
  51#define TIMER_PRESCALE 255
  52
  53int timer_init(void)
  54{
  55        const u32 emask = SCUTIMER_CONTROL_AUTO_RELOAD_MASK |
  56                        (TIMER_PRESCALE << SCUTIMER_CONTROL_PRESCALER_SHIFT) |
  57                        SCUTIMER_CONTROL_ENABLE_MASK;
  58
  59        gd->arch.timer_rate_hz = (gd->cpu_clk / 2) / (TIMER_PRESCALE + 1);
  60
  61        /* Load the timer counter register */
  62        writel(0xFFFFFFFF, &timer_base->load);
  63
  64        /*
  65         * Start the A9Timer device
  66         * Enable Auto reload mode, Clear prescaler control bits
  67         * Set prescaler value, Enable the decrementer
  68         */
  69        clrsetbits_le32(&timer_base->control, SCUTIMER_CONTROL_PRESCALER_MASK,
  70                                                                emask);
  71
  72        /* Reset time */
  73        gd->arch.lastinc = readl(&timer_base->counter) /
  74                                (gd->arch.timer_rate_hz / CONFIG_SYS_HZ);
  75        gd->arch.tbl = 0;
  76
  77        return 0;
  78}
  79
  80/*
  81 * This function is derived from PowerPC code (timebase clock frequency).
  82 * On ARM it returns the number of timer ticks per second.
  83 */
  84ulong get_tbclk(void)
  85{
  86        return gd->arch.timer_rate_hz;
  87}
  88