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         return (struct s5pc1xx_timer *)samsung_get_base_timer();
  50 }
  51
  52 int timer_init(void)
  53 {
  54         struct s5pc1xx_timer *const timer = s5pc1xx_get_base_timer();
  55         u32 val;
  56
  57         /*
  58          * @ PWM Timer 4
  59          * Timer Freq(HZ) =
  60          *      PCLK / { (prescaler_value + 1) * (divider_value) }
  61          */
  62
  63         /* set prescaler : 16 */
  64         /* set divider : 2 */
  65         writel((PRESCALER_1 & 0xff) << 8, &timer->tcfg0);
  66         writel((MUX_DIV_2 & 0xf) << MUX4_DIV_SHIFT, &timer->tcfg1);
  67
  68         if (count_value == 0) {
  69                 /* reset initial value */
  70                 /* count_value = 2085937.5(HZ) (per 1 sec)*/
  71                 count_value = get_pclk() / ((PRESCALER_1 + 1) *
  72                                 (MUX_DIV_2 + 1));
  73
  74                 /* count_value / 100 = 20859.375(HZ) (per 10 msec) */
  75                 count_value = count_value / 100;
  76         }
  77
  78         /* set count value */
  79         writel(count_value, &timer->tcntb4);
  80         lastdec = count_value;
  81
  82         val = (readl(&timer->tcon) & ~(0x07 << TCON_TIMER4_SHIFT)) |
  83                 S5PC1XX_TCON4_AUTO_RELOAD;
  84
  85         /* auto reload & manual update */
  86         writel(val | S5PC1XX_TCON4_UPDATE, &timer->tcon);
  87
  88         /* start PWM timer 4 */
  89         writel(val | S5PC1XX_TCON4_START, &timer->tcon);
  90
  91         timestamp = 0;
  92
  93         return 0;
  94 }
  95
  96 /*
  97  * timer without interrupts
  98  */
  99 void reset_timer(void)
 100 {
 101         reset_timer_masked();
 102 }
 103
 104 unsigned long get_timer(unsigned long base)
 105 {
 106         return get_timer_masked() - base;
 107 }
 108
 109 void set_timer(unsigned long t)
 110 {
 111         timestamp = t;
 112 }
 113
 114 /* delay x useconds */
 115 void __udelay(unsigned long usec)
 116 {
 117         unsigned long tmo, tmp;
 118
 119         if (usec >= 1000) {
 120                 /*
 121                  * if "big" number, spread normalization
 122                  * to seconds
 123                  * 1. start to normalize for usec to ticks per sec
 124                  * 2. find number of "ticks" to wait to achieve target
 125                  * 3. finish normalize.
 126                  */
 127                 tmo = usec / 1000;
 128                 tmo *= (CONFIG_SYS_HZ * count_value / 10);
 129                 tmo /= 1000;
 130         } else {
 131                 /* else small number, don't kill it prior to HZ multiply */
 132                 tmo = usec * CONFIG_SYS_HZ * count_value / 10;
 133                 tmo /= (1000 * 1000);
 134         }
 135
 136         /* get current timestamp */
 137         tmp = get_timer(0);
 138
 139         /* if setting this fordward will roll time stamp */
 140         /* reset "advancing" timestamp to 0, set lastdec value */
 141         /* else, set advancing stamp wake up time */
 142         if ((tmo + tmp + 1) < tmp)
 143                 reset_timer_masked();
 144         else
 145                 tmo += tmp;
 146
 147         /* loop till event */
 148         while (get_timer_masked() < tmo)
 149                 ;       /* nop */
 150 }
 151
 152 void reset_timer_masked(void)
 153 {
 154         struct s5pc1xx_timer *const timer = s5pc1xx_get_base_timer();
 155
 156         /* reset time */
 157         lastdec = readl(&timer->tcnto4);
 158         timestamp = 0;
 159 }
 160
 161 unsigned long get_timer_masked(void)
 162 {
 163         struct s5pc1xx_timer *const timer = s5pc1xx_get_base_timer();
 164         unsigned long now = readl(&timer->tcnto4);
 165
 166         if (lastdec >= now)
 167                 timestamp += lastdec - now;
 168         else
 169                 timestamp += lastdec + count_value - now;
 170
 171         lastdec = now;
 172
 173         return timestamp;
 174 }
 175
 176 /*
 177  * This function is derived from PowerPC code (read timebase as long long).
 178  * On ARM it just returns the timer value.
 179  */
 180 unsigned long long get_ticks(void)
 181 {
 182         return get_timer(0);
 183 }
 184
 185 /*
 186  * This function is derived from PowerPC code (timebase clock frequency).
 187  * On ARM it returns the number of timer ticks per second.
 188  */
 189 unsigned long get_tbclk(void)
 190 {
 191         return CONFIG_SYS_HZ;
 192 }