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time.c

/*
 * Support for periodic interrupts (100 per second) and for getting
 * the current time from the RTC on Power Macintoshes.
 *
 * We use the decrementer register for our periodic interrupts.
 *
 * Paul Mackerras August 1996.
 * Copyright (C) 1996 Paul Mackerras.
 * Copyright (C) 2003-2005 Benjamin Herrenschmidt.
 *
 */
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/time.h>
#include <linux/adb.h>
#include <linux/cuda.h>
#include <linux/pmu.h>
#include <linux/interrupt.h>
#include <linux/hardirq.h>
#include <linux/rtc.h>

#include <asm/sections.h>
#include <asm/prom.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/pgtable.h>
#include <asm/machdep.h>
#include <asm/time.h>
#include <asm/nvram.h>
#include <asm/smu.h>

#undef DEBUG

#ifdef DEBUG
#define DBG(x...) printk(x)
#else
#define DBG(x...)
#endif

/* Apparently the RTC stores seconds since 1 Jan 1904 */
#define RTC_OFFSET      2082844800

/*
 * Calibrate the decrementer frequency with the VIA timer 1.
 */
#define VIA_TIMER_FREQ_6      4700000     /* time 1 frequency * 6 */

/* VIA registers */
#define RS        0x200       /* skip between registers */
#define T1CL            (4*RS)            /* Timer 1 ctr/latch (low 8 bits) */
#define T1CH            (5*RS)            /* Timer 1 counter (high 8 bits) */
#define T1LL            (6*RS)            /* Timer 1 latch (low 8 bits) */
#define T1LH            (7*RS)            /* Timer 1 latch (high 8 bits) */
#define ACR       (11*RS)           /* Auxiliary control register */
#define IFR       (13*RS)           /* Interrupt flag register */

/* Bits in ACR */
#define T1MODE          0xc0        /* Timer 1 mode */
#define T1MODE_CONT     0x40        /*  continuous interrupts */

/* Bits in IFR and IER */
#define T1_INT          0x40        /* Timer 1 interrupt */

long __init pmac_time_init(void)
{
      s32 delta = 0;
#ifdef CONFIG_NVRAM
      int dst;
      
      delta = ((s32)pmac_xpram_read(PMAC_XPRAM_MACHINE_LOC + 0x9)) << 16;
      delta |= ((s32)pmac_xpram_read(PMAC_XPRAM_MACHINE_LOC + 0xa)) << 8;
      delta |= pmac_xpram_read(PMAC_XPRAM_MACHINE_LOC + 0xb);
      if (delta & 0x00800000UL)
            delta |= 0xFF000000UL;
      dst = ((pmac_xpram_read(PMAC_XPRAM_MACHINE_LOC + 0x8) & 0x80) != 0);
      printk("GMT Delta read from XPRAM: %d minutes, DST: %s\n", delta/60,
            dst ? "on" : "off");
#endif
      return delta;
}

#if defined(CONFIG_ADB_CUDA) || defined(CONFIG_ADB_PMU)
static void to_rtc_time(unsigned long now, struct rtc_time *tm)
{
      to_tm(now, tm);
      tm->tm_year -= 1900;
      tm->tm_mon -= 1;
}
#endif

#if defined(CONFIG_ADB_CUDA) || defined(CONFIG_ADB_PMU) || \
    defined(CONFIG_PMAC_SMU)
static unsigned long from_rtc_time(struct rtc_time *tm)
{
      return mktime(tm->tm_year+1900, tm->tm_mon+1, tm->tm_mday,
                  tm->tm_hour, tm->tm_min, tm->tm_sec);
}
#endif

#ifdef CONFIG_ADB_CUDA
static unsigned long cuda_get_time(void)
{
      struct adb_request req;
      unsigned int now;

      if (cuda_request(&req, NULL, 2, CUDA_PACKET, CUDA_GET_TIME) < 0)
            return 0;
      while (!req.complete)
            cuda_poll();
      if (req.reply_len != 7)
            printk(KERN_ERR "cuda_get_time: got %d byte reply\n",
                   req.reply_len);
      now = (req.reply[3] << 24) + (req.reply[4] << 16)
            + (req.reply[5] << 8) + req.reply[6];
      return ((unsigned long)now) - RTC_OFFSET;
}

#define cuda_get_rtc_time(tm) to_rtc_time(cuda_get_time(), (tm))

static int cuda_set_rtc_time(struct rtc_time *tm)
{
      unsigned int nowtime;
      struct adb_request req;

      nowtime = from_rtc_time(tm) + RTC_OFFSET;
      if (cuda_request(&req, NULL, 6, CUDA_PACKET, CUDA_SET_TIME,
                   nowtime >> 24, nowtime >> 16, nowtime >> 8,
                   nowtime) < 0)
            return -ENXIO;
      while (!req.complete)
            cuda_poll();
      if ((req.reply_len != 3) && (req.reply_len != 7))
            printk(KERN_ERR "cuda_set_rtc_time: got %d byte reply\n",
                   req.reply_len);
      return 0;
}

#else
#define cuda_get_time()       0
#define cuda_get_rtc_time(tm)
#define cuda_set_rtc_time(tm) 0
#endif

#ifdef CONFIG_ADB_PMU
static unsigned long pmu_get_time(void)
{
      struct adb_request req;
      unsigned int now;

      if (pmu_request(&req, NULL, 1, PMU_READ_RTC) < 0)
            return 0;
      pmu_wait_complete(&req);
      if (req.reply_len != 4)
            printk(KERN_ERR "pmu_get_time: got %d byte reply from PMU\n",
                   req.reply_len);
      now = (req.reply[0] << 24) + (req.reply[1] << 16)
            + (req.reply[2] << 8) + req.reply[3];
      return ((unsigned long)now) - RTC_OFFSET;
}

#define pmu_get_rtc_time(tm)  to_rtc_time(pmu_get_time(), (tm))

static int pmu_set_rtc_time(struct rtc_time *tm)
{
      unsigned int nowtime;
      struct adb_request req;

      nowtime = from_rtc_time(tm) + RTC_OFFSET;
      if (pmu_request(&req, NULL, 5, PMU_SET_RTC, nowtime >> 24,
                  nowtime >> 16, nowtime >> 8, nowtime) < 0)
            return -ENXIO;
      pmu_wait_complete(&req);
      if (req.reply_len != 0)
            printk(KERN_ERR "pmu_set_rtc_time: %d byte reply from PMU\n",
                   req.reply_len);
      return 0;
}

#else
#define pmu_get_time()        0
#define pmu_get_rtc_time(tm)
#define pmu_set_rtc_time(tm)  0
#endif

#ifdef CONFIG_PMAC_SMU
static unsigned long smu_get_time(void)
{
      struct rtc_time tm;

      if (smu_get_rtc_time(&tm, 1))
            return 0;
      return from_rtc_time(&tm);
}

#else
#define smu_get_time()              0
#define smu_get_rtc_time(tm, spin)
#define smu_set_rtc_time(tm, spin)  0
#endif

/* Can't be __init, it's called when suspending and resuming */
unsigned long pmac_get_boot_time(void)
{
      /* Get the time from the RTC, used only at boot time */
      switch (sys_ctrler) {
      case SYS_CTRLER_CUDA:
            return cuda_get_time();
      case SYS_CTRLER_PMU:
            return pmu_get_time();
      case SYS_CTRLER_SMU:
            return smu_get_time();
      default:
            return 0;
      }
}

void pmac_get_rtc_time(struct rtc_time *tm)
{
      /* Get the time from the RTC, used only at boot time */
      switch (sys_ctrler) {
      case SYS_CTRLER_CUDA:
            cuda_get_rtc_time(tm);
            break;
      case SYS_CTRLER_PMU:
            pmu_get_rtc_time(tm);
            break;
      case SYS_CTRLER_SMU:
            smu_get_rtc_time(tm, 1);
            break;
      default:
            ;
      }
}

int pmac_set_rtc_time(struct rtc_time *tm)
{
      switch (sys_ctrler) {
      case SYS_CTRLER_CUDA:
            return cuda_set_rtc_time(tm);
      case SYS_CTRLER_PMU:
            return pmu_set_rtc_time(tm);
      case SYS_CTRLER_SMU:
            return smu_set_rtc_time(tm, 1);
      default:
            return -ENODEV;
      }
}

#ifdef CONFIG_PPC32
/*
 * Calibrate the decrementer register using VIA timer 1.
 * This is used both on powermacs and CHRP machines.
 */
int __init via_calibrate_decr(void)
{
      struct device_node *vias;
      volatile unsigned char __iomem *via;
      int count = VIA_TIMER_FREQ_6 / 100;
      unsigned int dstart, dend;
      struct resource rsrc;

      vias = of_find_node_by_name(NULL, "via-cuda");
      if (vias == 0)
            vias = of_find_node_by_name(NULL, "via-pmu");
      if (vias == 0)
            vias = of_find_node_by_name(NULL, "via");
      if (vias == 0 || of_address_to_resource(vias, 0, &rsrc))
            return 0;
      via = ioremap(rsrc.start, rsrc.end - rsrc.start + 1);
      if (via == NULL) {
            printk(KERN_ERR "Failed to map VIA for timer calibration !\n");
            return 0;
      }

      /* set timer 1 for continuous interrupts */
      out_8(&via[ACR], (via[ACR] & ~T1MODE) | T1MODE_CONT);
      /* set the counter to a small value */
      out_8(&via[T1CH], 2);
      /* set the latch to `count' */
      out_8(&via[T1LL], count);
      out_8(&via[T1LH], count >> 8);
      /* wait until it hits 0 */
      while ((in_8(&via[IFR]) & T1_INT) == 0)
            ;
      dstart = get_dec();
      /* clear the interrupt & wait until it hits 0 again */
      in_8(&via[T1CL]);
      while ((in_8(&via[IFR]) & T1_INT) == 0)
            ;
      dend = get_dec();

      ppc_tb_freq = (dstart - dend) * 100 / 6;

      iounmap(via);
      
      return 1;
}
#endif

/*
 * Query the OF and get the decr frequency.
 */
void __init pmac_calibrate_decr(void)
{
      generic_calibrate_decr();

#ifdef CONFIG_PPC32
      /* We assume MacRISC2 machines have correct device-tree
       * calibration. That's better since the VIA itself seems
       * to be slightly off. --BenH
       */
      if (!machine_is_compatible("MacRISC2") &&
          !machine_is_compatible("MacRISC3") &&
          !machine_is_compatible("MacRISC4"))
            if (via_calibrate_decr())
                  return;

      /* Special case: QuickSilver G4s seem to have a badly calibrated
       * timebase-frequency in OF, VIA is much better on these. We should
       * probably implement calibration based on the KL timer on these
       * machines anyway... -BenH
       */
      if (machine_is_compatible("PowerMac3,5"))
            if (via_calibrate_decr())
                  return;
#endif
}

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