cpu/arm926ejs/spear/timer.c

   1 /*
   2  * (C) Copyright 2009
   3  * Vipin Kumar, ST Micoelectronics, vipin.kumar@st.com.
   4  *
   5  * See file CREDITS for list of people who contributed to this
   6  * project.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation; either version 2 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  21  * MA 02111-1307 USA
  22  */
  23
  24 #include <common.h>
  25 #include <asm/io.h>
  26 #include <asm/arch/hardware.h>
  27 #include <asm/arch/spr_gpt.h>
  28 #include <asm/arch/spr_misc.h>
  29
  30 #define GPT_RESOLUTION  (CONFIG_SPEAR_HZ_CLOCK / CONFIG_SPEAR_HZ)
  31 #define READ_TIMER()    (readl(&gpt_regs_p->count) & GPT_FREE_RUNNING)
  32
  33 static struct gpt_regs *const gpt_regs_p =
  34     (struct gpt_regs *)CONFIG_SPEAR_TIMERBASE;
  35
  36 static struct misc_regs *const misc_regs_p =
  37     (struct misc_regs *)CONFIG_SPEAR_MISCBASE;
  38
  39 static ulong timestamp;
  40 static ulong lastdec;
  41
  42 int timer_init(void)
  43 {
  44         u32 synth;
  45
  46         /* Prescaler setting */
  47 #if defined(CONFIG_SPEAR3XX)
  48         writel(MISC_PRSC_CFG, &misc_regs_p->prsc2_clk_cfg);
  49         synth = MISC_GPT4SYNTH;
  50 #elif defined(CONFIG_SPEAR600)
  51         writel(MISC_PRSC_CFG, &misc_regs_p->prsc1_clk_cfg);
  52         synth = MISC_GPT3SYNTH;
  53 #else
  54 # error Incorrect config. Can only be spear{600|300|310|320}
  55 #endif
  56
  57         writel(readl(&misc_regs_p->periph_clk_cfg) | synth,
  58                &misc_regs_p->periph_clk_cfg);
  59
  60         /* disable timers */
  61         writel(GPT_PRESCALER_1 | GPT_MODE_AUTO_RELOAD, &gpt_regs_p->control);
  62
  63         /* load value for free running */
  64         writel(GPT_FREE_RUNNING, &gpt_regs_p->compare);
  65
  66         /* auto reload, start timer */
  67         writel(readl(&gpt_regs_p->control) | GPT_ENABLE, &gpt_regs_p->control);
  68
  69         reset_timer_masked();
  70
  71         return 0;
  72 }
  73
  74 /*
  75  * timer without interrupts
  76  */
  77
  78 void reset_timer(void)
  79 {
  80         reset_timer_masked();
  81 }
  82
  83 ulong get_timer(ulong base)
  84 {
  85         return (get_timer_masked() / GPT_RESOLUTION) - base;
  86 }
  87
  88 void set_timer(ulong t)
  89 {
  90         timestamp = t;
  91 }
  92
  93 void __udelay(unsigned long usec)
  94 {
  95         ulong tmo;
  96         ulong start = get_timer_masked();
  97         ulong tenudelcnt = CONFIG_SPEAR_HZ_CLOCK / (1000 * 100);
  98         ulong rndoff;
  99
 100         rndoff = (usec % 10) ? 1 : 0;
 101
 102         /* tenudelcnt timer tick gives 10 microsecconds delay */
 103         tmo = ((usec / 10) + rndoff) * tenudelcnt;
 104
 105         while ((ulong) (get_timer_masked() - start) < tmo)
 106                 ;
 107 }
 108
 109 void reset_timer_masked(void)
 110 {
 111         /* reset time */
 112         lastdec = READ_TIMER();
 113         timestamp = 0;
 114 }
 115
 116 ulong get_timer_masked(void)
 117 {
 118         ulong now = READ_TIMER();
 119
 120         if (now >= lastdec) {
 121                 /* normal mode */
 122                 timestamp += now - lastdec;
 123         } else {
 124                 /* we have an overflow ... */
 125                 timestamp += now + GPT_FREE_RUNNING - lastdec;
 126         }
 127         lastdec = now;
 128
 129         return timestamp;
 130 }
 131
 132 void udelay_masked(unsigned long usec)
 133 {
 134         return udelay(usec);
 135 }
 136
 137 /*
 138  * This function is derived from PowerPC code (read timebase as long long).
 139  * On ARM it just returns the timer value.
 140  */
 141 unsigned long long get_ticks(void)
 142 {
 143         return get_timer(0);
 144 }
 145
 146 /*
 147  * This function is derived from PowerPC code (timebase clock frequency).
 148  * On ARM it returns the number of timer ticks per second.
 149  */
 150 ulong get_tbclk(void)
 151 {
 152         return CONFIG_SPEAR_HZ;
 153 }