arch/arm/cpu/armv7/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
  34 DECLARE_GLOBAL_DATA_PTR;
  35
  36 struct scu_timer {
  37         u32 load; /* Timer Load Register */
  38         u32 counter; /* Timer Counter Register */
  39         u32 control; /* Timer Control Register */
  40 };
  41
  42 static 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
  53 int 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 (read timebase as long long).
  82  * On ARM it just returns the timer value.
  83  */
  84 ulong get_timer_masked(void)
  85 {
  86         ulong now;
  87
  88         now = readl(&timer_base->counter) /
  89                         (gd->arch.timer_rate_hz / CONFIG_SYS_HZ);
  90
  91         if (gd->arch.lastinc >= now) {
  92                 /* Normal mode */
  93                 gd->arch.tbl += gd->arch.lastinc - now;
  94         } else {
  95                 /* We have an overflow ... */
  96                 gd->arch.tbl += gd->arch.lastinc + TIMER_LOAD_VAL - now + 1;
  97         }
  98         gd->arch.lastinc = now;
  99
 100         return gd->arch.tbl;
 101 }
 102
 103 void __udelay(unsigned long usec)
 104 {
 105         u32 countticks;
 106         u32 timeend;
 107         u32 timediff;
 108         u32 timenow;
 109
 110         if (usec == 0)
 111                 return;
 112
 113         countticks = lldiv(((unsigned long long)gd->arch.timer_rate_hz * usec),
 114                            1000000);
 115
 116         /* decrementing timer */
 117         timeend = readl(&timer_base->counter) - countticks;
 118
 119 #if TIMER_LOAD_VAL != 0xFFFFFFFF
 120         /* do not manage multiple overflow */
 121         if (countticks >= TIMER_LOAD_VAL)
 122                 countticks = TIMER_LOAD_VAL - 1;
 123 #endif
 124
 125         do {
 126                 timenow = readl(&timer_base->counter);
 127
 128                 if (timenow >= timeend) {
 129                         /* normal case */
 130                         timediff = timenow - timeend;
 131                 } else {
 132                         if ((TIMER_LOAD_VAL - timeend + timenow) <=
 133                                                                 countticks) {
 134                                 /* overflow */
 135                                 timediff = TIMER_LOAD_VAL - timeend + timenow;
 136                         } else {
 137                                 /* missed the exact match */
 138                                 break;
 139                         }
 140                 }
 141         } while (timediff > 0);
 142 }
 143
 144 /* Timer without interrupts */
 145 ulong get_timer(ulong base)
 146 {
 147         return get_timer_masked() - base;
 148 }
 149
 150 /*
 151  * This function is derived from PowerPC code (read timebase as long long).
 152  * On ARM it just returns the timer value.
 153  */
 154 unsigned long long get_ticks(void)
 155 {
 156         return get_timer(0);
 157 }
 158
 159 /*
 160  * This function is derived from PowerPC code (timebase clock frequency).
 161  * On ARM it returns the number of timer ticks per second.
 162  */
 163 ulong get_tbclk(void)
 164 {
 165         return CONFIG_SYS_HZ;
 166 }