arch/arm/plat-omap/counter_32k.c

   1 /*
   2  * OMAP 32ksynctimer/counter_32k-related code
   3  *
   4  * Copyright (C) 2009 Texas Instruments
   5  * Copyright (C) 2010 Nokia Corporation
   6  * Tony Lindgren <tony@atomide.com>
   7  * Added OMAP4 support - Santosh Shilimkar <santosh.shilimkar@ti.com>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  *
  13  * NOTE: This timer is not the same timer as the old OMAP1 MPU timer.
  14  */
  15 #include <linux/kernel.h>
  16 #include <linux/init.h>
  17 #include <linux/clk.h>
  18 #include <linux/io.h>
  19
  20 #include <plat/common.h>
  21 #include <plat/board.h>
  22
  23 #include <plat/clock.h>
  24
  25
  26 /*
  27  * 32KHz clocksource ... always available, on pretty most chips except
  28  * OMAP 730 and 1510.  Other timers could be used as clocksources, with
  29  * higher resolution in free-running counter modes (e.g. 12 MHz xtal),
  30  * but systems won't necessarily want to spend resources that way.
  31  */
  32
  33 #define OMAP16XX_TIMER_32K_SYNCHRONIZED         0xfffbc410
  34
  35 #if !(defined(CONFIG_ARCH_OMAP730) || defined(CONFIG_ARCH_OMAP15XX))
  36
  37 #include <linux/clocksource.h>
  38
  39 /*
  40  * offset_32k holds the init time counter value. It is then subtracted
  41  * from every counter read to achieve a counter that counts time from the
  42  * kernel boot (needed for sched_clock()).
  43  */
  44 static u32 offset_32k __read_mostly;
  45
  46 #ifdef CONFIG_ARCH_OMAP16XX
  47 static cycle_t omap16xx_32k_read(struct clocksource *cs)
  48 {
  49         return omap_readl(OMAP16XX_TIMER_32K_SYNCHRONIZED) - offset_32k;
  50 }
  51 #else
  52 #define omap16xx_32k_read       NULL
  53 #endif
  54
  55 #ifdef CONFIG_ARCH_OMAP2420
  56 static cycle_t omap2420_32k_read(struct clocksource *cs)
  57 {
  58         return omap_readl(OMAP2420_32KSYNCT_BASE + 0x10) - offset_32k;
  59 }
  60 #else
  61 #define omap2420_32k_read       NULL
  62 #endif
  63
  64 #ifdef CONFIG_ARCH_OMAP2430
  65 static cycle_t omap2430_32k_read(struct clocksource *cs)
  66 {
  67         return omap_readl(OMAP2430_32KSYNCT_BASE + 0x10) - offset_32k;
  68 }
  69 #else
  70 #define omap2430_32k_read       NULL
  71 #endif
  72
  73 #ifdef CONFIG_ARCH_OMAP3
  74 static cycle_t omap34xx_32k_read(struct clocksource *cs)
  75 {
  76         return omap_readl(OMAP3430_32KSYNCT_BASE + 0x10) - offset_32k;
  77 }
  78 #else
  79 #define omap34xx_32k_read       NULL
  80 #endif
  81
  82 #ifdef CONFIG_ARCH_OMAP4
  83 static cycle_t omap44xx_32k_read(struct clocksource *cs)
  84 {
  85         return omap_readl(OMAP4430_32KSYNCT_BASE + 0x10) - offset_32k;
  86 }
  87 #else
  88 #define omap44xx_32k_read       NULL
  89 #endif
  90
  91 /*
  92  * Kernel assumes that sched_clock can be called early but may not have
  93  * things ready yet.
  94  */
  95 static cycle_t omap_32k_read_dummy(struct clocksource *cs)
  96 {
  97         return 0;
  98 }
  99
 100 static struct clocksource clocksource_32k = {
 101         .name           = "32k_counter",
 102         .rating         = 250,
 103         .read           = omap_32k_read_dummy,
 104         .mask           = CLOCKSOURCE_MASK(32),
 105         .shift          = 10,
 106         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 107 };
 108
 109 /*
 110  * Returns current time from boot in nsecs. It's OK for this to wrap
 111  * around for now, as it's just a relative time stamp.
 112  */
 113 unsigned long long sched_clock(void)
 114 {
 115         return clocksource_cyc2ns(clocksource_32k.read(&clocksource_32k),
 116                                   clocksource_32k.mult, clocksource_32k.shift);
 117 }
 118
 119 /**
 120  * read_persistent_clock -  Return time from a persistent clock.
 121  *
 122  * Reads the time from a source which isn't disabled during PM, the
 123  * 32k sync timer.  Convert the cycles elapsed since last read into
 124  * nsecs and adds to a monotonically increasing timespec.
 125  */
 126 static struct timespec persistent_ts;
 127 static cycles_t cycles, last_cycles;
 128 void read_persistent_clock(struct timespec *ts)
 129 {
 130         unsigned long long nsecs;
 131         cycles_t delta;
 132         struct timespec *tsp = &persistent_ts;
 133
 134         last_cycles = cycles;
 135         cycles = clocksource_32k.read(&clocksource_32k);
 136         delta = cycles - last_cycles;
 137
 138         nsecs = clocksource_cyc2ns(delta,
 139                                    clocksource_32k.mult, clocksource_32k.shift);
 140
 141         timespec_add_ns(tsp, nsecs);
 142         *ts = *tsp;
 143 }
 144
 145 static int __init omap_init_clocksource_32k(void)
 146 {
 147         static char err[] __initdata = KERN_ERR
 148                         "%s: can't register clocksource!\n";
 149
 150         if (cpu_is_omap16xx() || cpu_class_is_omap2()) {
 151                 struct clk *sync_32k_ick;
 152
 153                 if (cpu_is_omap16xx())
 154                         clocksource_32k.read = omap16xx_32k_read;
 155                 else if (cpu_is_omap2420())
 156                         clocksource_32k.read = omap2420_32k_read;
 157                 else if (cpu_is_omap2430())
 158                         clocksource_32k.read = omap2430_32k_read;
 159                 else if (cpu_is_omap34xx())
 160                         clocksource_32k.read = omap34xx_32k_read;
 161                 else if (cpu_is_omap44xx())
 162                         clocksource_32k.read = omap44xx_32k_read;
 163                 else
 164                         return -ENODEV;
 165
 166                 sync_32k_ick = clk_get(NULL, "omap_32ksync_ick");
 167                 if (sync_32k_ick)
 168                         clk_enable(sync_32k_ick);
 169
 170                 clocksource_32k.mult = clocksource_hz2mult(32768,
 171                                             clocksource_32k.shift);
 172
 173                 offset_32k = clocksource_32k.read(&clocksource_32k);
 174
 175                 if (clocksource_register(&clocksource_32k))
 176                         printk(err, clocksource_32k.name);
 177         }
 178         return 0;
 179 }
 180 arch_initcall(omap_init_clocksource_32k);
 181
 182 #endif  /* !(defined(CONFIG_ARCH_OMAP730) || defined(CONFIG_ARCH_OMAP15XX)) */
 183