arch/arm/cpu/armv7/s5pc1xx/timer.c

   1 /*
   2  * Copyright (C) 2009 Samsung Electronics
   3  * Heungjun Kim <riverful.kim@samsung.com>
   4  * Inki Dae <inki.dae@samsung.com>
   5  * Minkyu Kang <mk7.kang@samsung.com>
   6  *
   7  * See file CREDITS for list of people who contributed to this
   8  * project.
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License as
  12  * published by the Free Software Foundation; either version 2 of
  13  * the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  23  * MA 02111-1307 USA
  24  */
  25
  26 #include <common.h>
  27 #include <asm/io.h>
  28 #include <asm/arch/pwm.h>
  29 #include <asm/arch/clk.h>
  30
  31 #define PRESCALER_1             (16 - 1)        /* prescaler of timer 2, 3, 4 */
  32 #define MUX_DIV_2               1               /* 1/2 period */
  33 #define MUX_DIV_4               2               /* 1/4 period */
  34 #define MUX_DIV_8               3               /* 1/8 period */
  35 #define MUX_DIV_16              4               /* 1/16 period */
  36 #define MUX4_DIV_SHIFT          16
  37
  38 #define TCON_TIMER4_SHIFT       20
  39
  40 static unsigned long count_value;
  41
  42 /* Internal tick units */
  43 static unsigned long long timestamp;    /* Monotonic incrementing timer */
  44 static unsigned long lastdec;           /* Last decremneter snapshot */
  45
  46 /* macro to read the 16 bit timer */
  47 static inline struct s5pc1xx_timer *s5pc1xx_get_base_timer(void)
  48 {
  49         if (cpu_is_s5pc110())
  50                 return (struct s5pc1xx_timer *)S5PC110_TIMER_BASE;
  51         else
  52                 return (struct s5pc1xx_timer *)S5PC100_TIMER_BASE;
  53 }
  54
  55 int timer_init(void)
  56 {
  57         struct s5pc1xx_timer *const timer = s5pc1xx_get_base_timer();
  58         u32 val;
  59
  60         /*
  61          * @ PWM Timer 4
  62          * Timer Freq(HZ) =
  63          *      PCLK / { (prescaler_value + 1) * (divider_value) }
  64          */
  65
  66         /* set prescaler : 16 */
  67         /* set divider : 2 */
  68         writel((PRESCALER_1 & 0xff) << 8, &timer->tcfg0);
  69         writel((MUX_DIV_2 & 0xf) << MUX4_DIV_SHIFT, &timer->tcfg1);
  70
  71         if (count_value == 0) {
  72                 /* reset initial value */
  73                 /* count_value = 2085937.5(HZ) (per 1 sec)*/
  74                 count_value = get_pclk() / ((PRESCALER_1 + 1) *
  75                                 (MUX_DIV_2 + 1));
  76
  77                 /* count_value / 100 = 20859.375(HZ) (per 10 msec) */
  78                 count_value = count_value / 100;
  79         }
  80
  81         /* set count value */
  82         writel(count_value, &timer->tcntb4);
  83         lastdec = count_value;
  84
  85         val = (readl(&timer->tcon) & ~(0x07 << TCON_TIMER4_SHIFT)) |
  86                 S5PC1XX_TCON4_AUTO_RELOAD;
  87
  88         /* auto reload & manual update */
  89         writel(val | S5PC1XX_TCON4_UPDATE, &timer->tcon);
  90
  91         /* start PWM timer 4 */
  92         writel(val | S5PC1XX_TCON4_START, &timer->tcon);
  93
  94         timestamp = 0;
  95
  96         return 0;
  97 }
  98
  99 /*
 100  * timer without interrupts
 101  */
 102 void reset_timer(void)
 103 {
 104         reset_timer_masked();
 105 }
 106
 107 unsigned long get_timer(unsigned long base)
 108 {
 109         return get_timer_masked() - base;
 110 }
 111
 112 void set_timer(unsigned long t)
 113 {
 114         timestamp = t;
 115 }
 116
 117 /* delay x useconds */
 118 void __udelay(unsigned long usec)
 119 {
 120         unsigned long tmo, tmp;
 121
 122         if (usec >= 1000) {
 123                 /*
 124                  * if "big" number, spread normalization
 125                  * to seconds
 126                  * 1. start to normalize for usec to ticks per sec
 127                  * 2. find number of "ticks" to wait to achieve target
 128                  * 3. finish normalize.
 129                  */
 130                 tmo = usec / 1000;
 131                 tmo *= (CONFIG_SYS_HZ * count_value / 10);
 132                 tmo /= 1000;
 133         } else {
 134                 /* else small number, don't kill it prior to HZ multiply */
 135                 tmo = usec * CONFIG_SYS_HZ * count_value / 10;
 136                 tmo /= (1000 * 1000);
 137         }
 138
 139         /* get current timestamp */
 140         tmp = get_timer(0);
 141
 142         /* if setting this fordward will roll time stamp */
 143         /* reset "advancing" timestamp to 0, set lastdec value */
 144         /* else, set advancing stamp wake up time */
 145         if ((tmo + tmp + 1) < tmp)
 146                 reset_timer_masked();
 147         else
 148                 tmo += tmp;
 149
 150         /* loop till event */
 151         while (get_timer_masked() < tmo)
 152                 ;       /* nop */
 153 }
 154
 155 void reset_timer_masked(void)
 156 {
 157         struct s5pc1xx_timer *const timer = s5pc1xx_get_base_timer();
 158
 159         /* reset time */
 160         lastdec = readl(&timer->tcnto4);
 161         timestamp = 0;
 162 }
 163
 164 unsigned long get_timer_masked(void)
 165 {
 166         struct s5pc1xx_timer *const timer = s5pc1xx_get_base_timer();
 167         unsigned long now = readl(&timer->tcnto4);
 168
 169         if (lastdec >= now)
 170                 timestamp += lastdec - now;
 171         else
 172                 timestamp += lastdec + count_value - now;
 173
 174         lastdec = now;
 175
 176         return timestamp;
 177 }
 178
 179 /*
 180  * This function is derived from PowerPC code (read timebase as long long).
 181  * On ARM it just returns the timer value.
 182  */
 183 unsigned long long get_ticks(void)
 184 {
 185         return get_timer(0);
 186 }
 187
 188 /*
 189  * This function is derived from PowerPC code (timebase clock frequency).
 190  * On ARM it returns the number of timer ticks per second.
 191  */
 192 unsigned long get_tbclk(void)
 193 {
 194         return CONFIG_SYS_HZ;
 195 }