drivers/clocksource/cyclone.c

   1 #include <linux/clocksource.h>
   2 #include <linux/string.h>
   3 #include <linux/errno.h>
   4 #include <linux/timex.h>
   5 #include <linux/init.h>
   6
   7 #include <asm/pgtable.h>
   8 #include <asm/io.h>
   9
  10 #include <asm/mach_timer.h>
  11
  12 #define CYCLONE_CBAR_ADDR       0xFEB00CD0      /* base address ptr */
  13 #define CYCLONE_PMCC_OFFSET     0x51A0          /* offset to control register */
  14 #define CYCLONE_MPCS_OFFSET     0x51A8          /* offset to select register */
  15 #define CYCLONE_MPMC_OFFSET     0x51D0          /* offset to count register */
  16 #define CYCLONE_TIMER_FREQ      99780000        /* 100Mhz, but not really */
  17 #define CYCLONE_TIMER_MASK      CLOCKSOURCE_MASK(32) /* 32 bit mask */
  18
  19 int use_cyclone = 0;
  20 static void __iomem *cyclone_ptr;
  21
  22 static cycle_t read_cyclone(void)
  23 {
  24         return (cycle_t)readl(cyclone_ptr);
  25 }
  26
  27 static struct clocksource clocksource_cyclone = {
  28         .name           = "cyclone",
  29         .rating         = 250,
  30         .read           = read_cyclone,
  31         .mask           = CYCLONE_TIMER_MASK,
  32         .mult           = 10,
  33         .shift          = 0,
  34         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  35 };
  36
  37 static int __init init_cyclone_clocksource(void)
  38 {
  39         unsigned long base;     /* saved value from CBAR */
  40         unsigned long offset;
  41         u32 __iomem* volatile cyclone_timer;    /* Cyclone MPMC0 register */
  42         u32 __iomem* reg;
  43         int i;
  44
  45         /* make sure we're on a summit box: */
  46         if (!use_cyclone)
  47                 return -ENODEV;
  48
  49         printk(KERN_INFO "Summit chipset: Starting Cyclone Counter.\n");
  50
  51         /* find base address: */
  52         offset = CYCLONE_CBAR_ADDR;
  53         reg = ioremap_nocache(offset, sizeof(reg));
  54         if (!reg) {
  55                 printk(KERN_ERR "Summit chipset: Could not find valid CBAR register.\n");
  56                 return -ENODEV;
  57         }
  58         /* even on 64bit systems, this is only 32bits: */
  59         base = readl(reg);
  60         if (!base) {
  61                 printk(KERN_ERR "Summit chipset: Could not find valid CBAR value.\n");
  62                 return -ENODEV;
  63         }
  64         iounmap(reg);
  65
  66         /* setup PMCC: */
  67         offset = base + CYCLONE_PMCC_OFFSET;
  68         reg = ioremap_nocache(offset, sizeof(reg));
  69         if (!reg) {
  70                 printk(KERN_ERR "Summit chipset: Could not find valid PMCC register.\n");
  71                 return -ENODEV;
  72         }
  73         writel(0x00000001,reg);
  74         iounmap(reg);
  75
  76         /* setup MPCS: */
  77         offset = base + CYCLONE_MPCS_OFFSET;
  78         reg = ioremap_nocache(offset, sizeof(reg));
  79         if (!reg) {
  80                 printk(KERN_ERR "Summit chipset: Could not find valid MPCS register.\n");
  81                 return -ENODEV;
  82         }
  83         writel(0x00000001,reg);
  84         iounmap(reg);
  85
  86         /* map in cyclone_timer: */
  87         offset = base + CYCLONE_MPMC_OFFSET;
  88         cyclone_timer = ioremap_nocache(offset, sizeof(u64));
  89         if (!cyclone_timer) {
  90                 printk(KERN_ERR "Summit chipset: Could not find valid MPMC register.\n");
  91                 return -ENODEV;
  92         }
  93
  94         /* quick test to make sure its ticking: */
  95         for (i = 0; i < 3; i++){
  96                 u32 old = readl(cyclone_timer);
  97                 int stall = 100;
  98
  99                 while (stall--)
 100                         barrier();
 101
 102                 if (readl(cyclone_timer) == old) {
 103                         printk(KERN_ERR "Summit chipset: Counter not counting! DISABLED\n");
 104                         iounmap(cyclone_timer);
 105                         cyclone_timer = NULL;
 106                         return -ENODEV;
 107                 }
 108         }
 109         cyclone_ptr = cyclone_timer;
 110
 111         /* sort out mult/shift values: */
 112         clocksource_cyclone.shift = 22;
 113         clocksource_cyclone.mult = clocksource_hz2mult(CYCLONE_TIMER_FREQ,
 114                                                 clocksource_cyclone.shift);
 115
 116         return clocksource_register(&clocksource_cyclone);
 117 }
 118
 119 arch_initcall(init_cyclone_clocksource);