arch/i386/kernel/timers/timer_cyclone.c

   1 /*      Cyclone-timer:
   2  *              This code implements timer_ops for the cyclone counter found
   3  *              on IBM x440, x360, and other Summit based systems.
   4  *
   5  *      Copyright (C) 2002 IBM, John Stultz (johnstul@us.ibm.com)
   6  */
   7
   8
   9 #include <linux/spinlock.h>
  10 #include <linux/init.h>
  11 #include <linux/timex.h>
  12 #include <linux/errno.h>
  13 #include <linux/string.h>
  14 #include <linux/jiffies.h>
  15
  16 #include <asm/timer.h>
  17 #include <asm/io.h>
  18 #include <asm/pgtable.h>
  19 #include <asm/fixmap.h>
  20 #include "io_ports.h"
  21
  22 extern spinlock_t i8253_lock;
  23
  24 /* Number of usecs that the last interrupt was delayed */
  25 static int delay_at_last_interrupt;
  26
  27 #define CYCLONE_CBAR_ADDR 0xFEB00CD0
  28 #define CYCLONE_PMCC_OFFSET 0x51A0
  29 #define CYCLONE_MPMC_OFFSET 0x51D0
  30 #define CYCLONE_MPCS_OFFSET 0x51A8
  31 #define CYCLONE_TIMER_FREQ 100000000
  32 #define CYCLONE_TIMER_MASK (((u64)1<<40)-1) /* 40 bit mask */
  33 int use_cyclone = 0;
  34
  35 static u32* volatile cyclone_timer;     /* Cyclone MPMC0 register */
  36 static u32 last_cyclone_low;
  37 static u32 last_cyclone_high;
  38 static unsigned long long monotonic_base;
  39 static seqlock_t monotonic_lock = SEQLOCK_UNLOCKED;
  40
  41 /* helper macro to atomically read both cyclone counter registers */
  42 #define read_cyclone_counter(low,high) \
  43         do{ \
  44                 high = cyclone_timer[1]; low = cyclone_timer[0]; \
  45         } while (high != cyclone_timer[1]);
  46
  47
  48 static void mark_offset_cyclone(void)
  49 {
  50         unsigned long lost, delay;
  51         unsigned long delta = last_cyclone_low;
  52         int count;
  53         unsigned long long this_offset, last_offset;
  54
  55         write_seqlock(&monotonic_lock);
  56         last_offset = ((unsigned long long)last_cyclone_high<<32)|last_cyclone_low;
  57
  58         spin_lock(&i8253_lock);
  59         read_cyclone_counter(last_cyclone_low,last_cyclone_high);
  60
  61         /* read values for delay_at_last_interrupt */
  62         outb_p(0x00, 0x43);     /* latch the count ASAP */
  63
  64         count = inb_p(0x40);    /* read the latched count */
  65         count |= inb(0x40) << 8;
  66
  67         /*
  68          * VIA686a test code... reset the latch if count > max + 1
  69          * from timer_pit.c - cjb
  70          */
  71         if (count > LATCH) {
  72                 outb_p(0x34, PIT_MODE);
  73                 outb_p(LATCH & 0xff, PIT_CH0);
  74                 outb(LATCH >> 8, PIT_CH0);
  75                 count = LATCH - 1;
  76         }
  77         spin_unlock(&i8253_lock);
  78
  79         /* lost tick compensation */
  80         delta = last_cyclone_low - delta;
  81         delta /= (CYCLONE_TIMER_FREQ/1000000);
  82         delta += delay_at_last_interrupt;
  83         lost = delta/(1000000/HZ);
  84         delay = delta%(1000000/HZ);
  85         if (lost >= 2)
  86                 jiffies_64 += lost-1;
  87
  88         /* update the monotonic base value */
  89         this_offset = ((unsigned long long)last_cyclone_high<<32)|last_cyclone_low;
  90         monotonic_base += (this_offset - last_offset) & CYCLONE_TIMER_MASK;
  91         write_sequnlock(&monotonic_lock);
  92
  93         /* calculate delay_at_last_interrupt */
  94         count = ((LATCH-1) - count) * TICK_SIZE;
  95         delay_at_last_interrupt = (count + LATCH/2) / LATCH;
  96
  97
  98         /* catch corner case where tick rollover occured
  99          * between cyclone and pit reads (as noted when
 100          * usec delta is > 90% # of usecs/tick)
 101          */
 102         if (lost && abs(delay - delay_at_last_interrupt) > (900000/HZ))
 103                 jiffies_64++;
 104 }
 105
 106 static unsigned long get_offset_cyclone(void)
 107 {
 108         u32 offset;
 109
 110         if(!cyclone_timer)
 111                 return delay_at_last_interrupt;
 112
 113         /* Read the cyclone timer */
 114         offset = cyclone_timer[0];
 115
 116         /* .. relative to previous jiffy */
 117         offset = offset - last_cyclone_low;
 118
 119         /* convert cyclone ticks to microseconds */
 120         /* XXX slow, can we speed this up? */
 121         offset = offset/(CYCLONE_TIMER_FREQ/1000000);
 122
 123         /* our adjusted time offset in microseconds */
 124         return delay_at_last_interrupt + offset;
 125 }
 126
 127 static unsigned long long monotonic_clock_cyclone(void)
 128 {
 129         u32 now_low, now_high;
 130         unsigned long long last_offset, this_offset, base;
 131         unsigned long long ret;
 132         unsigned seq;
 133
 134         /* atomically read monotonic base & last_offset */
 135         do {
 136                 seq = read_seqbegin(&monotonic_lock);
 137                 last_offset = ((unsigned long long)last_cyclone_high<<32)|last_cyclone_low;
 138                 base = monotonic_base;
 139         } while (read_seqretry(&monotonic_lock, seq));
 140
 141
 142         /* Read the cyclone counter */
 143         read_cyclone_counter(now_low,now_high);
 144         this_offset = ((unsigned long long)now_high<<32)|now_low;
 145
 146         /* convert to nanoseconds */
 147         ret = base + ((this_offset - last_offset)&CYCLONE_TIMER_MASK);
 148         return ret * (1000000000 / CYCLONE_TIMER_FREQ);
 149 }
 150
 151 static int __init init_cyclone(char* override)
 152 {
 153         u32* reg;
 154         u32 base;               /* saved cyclone base address */
 155         u32 pageaddr;   /* page that contains cyclone_timer register */
 156         u32 offset;             /* offset from pageaddr to cyclone_timer register */
 157         int i;
 158
 159         /* check clock override */
 160         if (override[0] && strncmp(override,"cyclone",7))
 161                         return -ENODEV;
 162
 163         /*make sure we're on a summit box*/
 164         if(!use_cyclone) return -ENODEV;
 165
 166         printk(KERN_INFO "Summit chipset: Starting Cyclone Counter.\n");
 167
 168         /* find base address */
 169         pageaddr = (CYCLONE_CBAR_ADDR)&PAGE_MASK;
 170         offset = (CYCLONE_CBAR_ADDR)&(~PAGE_MASK);
 171         set_fixmap_nocache(FIX_CYCLONE_TIMER, pageaddr);
 172         reg = (u32*)(fix_to_virt(FIX_CYCLONE_TIMER) + offset);
 173         if(!reg){
 174                 printk(KERN_ERR "Summit chipset: Could not find valid CBAR register.\n");
 175                 return -ENODEV;
 176         }
 177         base = *reg;
 178         if(!base){
 179                 printk(KERN_ERR "Summit chipset: Could not find valid CBAR value.\n");
 180                 return -ENODEV;
 181         }
 182
 183         /* setup PMCC */
 184         pageaddr = (base + CYCLONE_PMCC_OFFSET)&PAGE_MASK;
 185         offset = (base + CYCLONE_PMCC_OFFSET)&(~PAGE_MASK);
 186         set_fixmap_nocache(FIX_CYCLONE_TIMER, pageaddr);
 187         reg = (u32*)(fix_to_virt(FIX_CYCLONE_TIMER) + offset);
 188         if(!reg){
 189                 printk(KERN_ERR "Summit chipset: Could not find valid PMCC register.\n");
 190                 return -ENODEV;
 191         }
 192         reg[0] = 0x00000001;
 193
 194         /* setup MPCS */
 195         pageaddr = (base + CYCLONE_MPCS_OFFSET)&PAGE_MASK;
 196         offset = (base + CYCLONE_MPCS_OFFSET)&(~PAGE_MASK);
 197         set_fixmap_nocache(FIX_CYCLONE_TIMER, pageaddr);
 198         reg = (u32*)(fix_to_virt(FIX_CYCLONE_TIMER) + offset);
 199         if(!reg){
 200                 printk(KERN_ERR "Summit chipset: Could not find valid MPCS register.\n");
 201                 return -ENODEV;
 202         }
 203         reg[0] = 0x00000001;
 204
 205         /* map in cyclone_timer */
 206         pageaddr = (base + CYCLONE_MPMC_OFFSET)&PAGE_MASK;
 207         offset = (base + CYCLONE_MPMC_OFFSET)&(~PAGE_MASK);
 208         set_fixmap_nocache(FIX_CYCLONE_TIMER, pageaddr);
 209         cyclone_timer = (u32*)(fix_to_virt(FIX_CYCLONE_TIMER) + offset);
 210         if(!cyclone_timer){
 211                 printk(KERN_ERR "Summit chipset: Could not find valid MPMC register.\n");
 212                 return -ENODEV;
 213         }
 214
 215         /*quick test to make sure its ticking*/
 216         for(i=0; i<3; i++){
 217                 u32 old = cyclone_timer[0];
 218                 int stall = 100;
 219                 while(stall--) barrier();
 220                 if(cyclone_timer[0] == old){
 221                         printk(KERN_ERR "Summit chipset: Counter not counting! DISABLED\n");
 222                         cyclone_timer = 0;
 223                         return -ENODEV;
 224                 }
 225         }
 226
 227         init_cpu_khz();
 228
 229         /* Everything looks good! */
 230         return 0;
 231 }
 232
 233
 234 static void delay_cyclone(unsigned long loops)
 235 {
 236         unsigned long bclock, now;
 237         if(!cyclone_timer)
 238                 return;
 239         bclock = cyclone_timer[0];
 240         do {
 241                 rep_nop();
 242                 now = cyclone_timer[0];
 243         } while ((now-bclock) < loops);
 244 }
 245 /************************************************************/
 246
 247 /* cyclone timer_opts struct */
 248 static struct timer_opts timer_cyclone = {
 249         .name = "cyclone",
 250         .mark_offset = mark_offset_cyclone,
 251         .get_offset = get_offset_cyclone,
 252         .monotonic_clock =      monotonic_clock_cyclone,
 253         .delay = delay_cyclone,
 254 };
 255
 256 struct init_timer_opts __initdata timer_cyclone_init = {
 257         .init = init_cyclone,
 258         .opts = &timer_cyclone,
 259 };