hw/slavio_timer.c - qemu - Git at Google

 /*
  * QEMU Sparc SLAVIO timer controller emulation
  *
  * Copyright (c) 2003-2005 Fabrice Bellard
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
 #include "hw.h"
 #include "sun4m.h"
 #include "qemu-timer.h"

 //#define DEBUG_TIMER

 #ifdef DEBUG_TIMER
 #define DPRINTF(fmt, ...)                                       \
     do { printf("TIMER: " fmt , ## __VA_ARGS__); } while (0)
 #else
 #define DPRINTF(fmt, ...) do {} while (0)
 #endif

 /*
  * Registers of hardware timer in sun4m.
  *
  * This is the timer/counter part of chip STP2001 (Slave I/O), also
  * produced as NCR89C105. See
  * http://www.ibiblio.org/pub/historic-linux/early-ports/Sparc/NCR/NCR89C105.txt
  *
  * The 31-bit counter is incremented every 500ns by bit 9. Bits 8..0
  * are zero. Bit 31 is 1 when count has been reached.
  *
  * Per-CPU timers interrupt local CPU, system timer uses normal
  * interrupt routing.
  *
  */

 #define MAX_CPUS 16

 typedef struct SLAVIO_TIMERState {
     qemu_irq irq;
     ptimer_state *timer;
     uint32_t count, counthigh, reached;
     uint64_t limit;
     // processor only
     uint32_t running;
     struct SLAVIO_TIMERState *master;
     uint32_t slave_index;
     // system only
     uint32_t num_slaves;
     struct SLAVIO_TIMERState *slave[MAX_CPUS];
     uint32_t slave_mode;
 } SLAVIO_TIMERState;

 #define SYS_TIMER_SIZE 0x14
 #define CPU_TIMER_SIZE 0x10

 #define SYS_TIMER_OFFSET      0x10000ULL
 #define CPU_TIMER_OFFSET(cpu) (0x1000ULL * cpu)

 #define TIMER_LIMIT         0
 #define TIMER_COUNTER       1
 #define TIMER_COUNTER_NORST 2
 #define TIMER_STATUS        3
 #define TIMER_MODE          4

 #define TIMER_COUNT_MASK32 0xfffffe00
 #define TIMER_LIMIT_MASK32 0x7fffffff
 #define TIMER_MAX_COUNT64  0x7ffffffffffffe00ULL
 #define TIMER_MAX_COUNT32  0x7ffffe00ULL
 #define TIMER_REACHED      0x80000000
 #define TIMER_PERIOD       500ULL // 500ns
 #define LIMIT_TO_PERIODS(l) ((l) >> 9)
 #define PERIODS_TO_LIMIT(l) ((l) << 9)

 static int slavio_timer_is_user(SLAVIO_TIMERState *s)
 {
     return s->master && (s->master->slave_mode & (1 << s->slave_index));
 }

 // Update count, set irq, update expire_time
 // Convert from ptimer countdown units
 static void slavio_timer_get_out(SLAVIO_TIMERState *s)
 {
     uint64_t count, limit;

     if (s->limit == 0) /* free-run processor or system counter */
         limit = TIMER_MAX_COUNT32;
     else
         limit = s->limit;

     if (s->timer)
         count = limit - PERIODS_TO_LIMIT(ptimer_get_count(s->timer));
     else
         count = 0;

     DPRINTF("get_out: limit %" PRIx64 " count %x%08x\n", s->limit,
             s->counthigh, s->count);
     s->count = count & TIMER_COUNT_MASK32;
     s->counthigh = count >> 32;
 }

 // timer callback
 static void slavio_timer_irq(void *opaque)
 {
     SLAVIO_TIMERState *s = opaque;

     slavio_timer_get_out(s);
     DPRINTF("callback: count %x%08x\n", s->counthigh, s->count);
     s->reached = TIMER_REACHED;
     if (!slavio_timer_is_user(s))
         qemu_irq_raise(s->irq);
 }

 static uint32_t slavio_timer_mem_readl(void *opaque, target_phys_addr_t addr)
 {
     SLAVIO_TIMERState *s = opaque;
     uint32_t saddr, ret;

     saddr = addr >> 2;
     switch (saddr) {
     case TIMER_LIMIT:
         // read limit (system counter mode) or read most signifying
         // part of counter (user mode)
         if (slavio_timer_is_user(s)) {
             // read user timer MSW
             slavio_timer_get_out(s);
             ret = s->counthigh | s->reached;
         } else {
             // read limit
             // clear irq
             qemu_irq_lower(s->irq);
             s->reached = 0;
             ret = s->limit & TIMER_LIMIT_MASK32;
         }
         break;
     case TIMER_COUNTER:
         // read counter and reached bit (system mode) or read lsbits
         // of counter (user mode)
         slavio_timer_get_out(s);
         if (slavio_timer_is_user(s)) // read user timer LSW
             ret = s->count & TIMER_MAX_COUNT64;
         else // read limit
             ret = (s->count & TIMER_MAX_COUNT32) | s->reached;
         break;
     case TIMER_STATUS:
         // only available in processor counter/timer
         // read start/stop status
         ret = s->running;
         break;
     case TIMER_MODE:
         // only available in system counter
         // read user/system mode
         ret = s->slave_mode;
         break;
     default:
         DPRINTF("invalid read address " TARGET_FMT_plx "\n", addr);
         ret = 0;
         break;
     }
     DPRINTF("read " TARGET_FMT_plx " = %08x\n", addr, ret);

     return ret;
 }

 static void slavio_timer_mem_writel(void *opaque, target_phys_addr_t addr,
                                     uint32_t val)
 {
     SLAVIO_TIMERState *s = opaque;
     uint32_t saddr;

     DPRINTF("write " TARGET_FMT_plx " %08x\n", addr, val);
     saddr = addr >> 2;
     switch (saddr) {
     case TIMER_LIMIT:
         if (slavio_timer_is_user(s)) {
             uint64_t count;

             // set user counter MSW, reset counter
             s->limit = TIMER_MAX_COUNT64;
             s->counthigh = val & (TIMER_MAX_COUNT64 >> 32);
             s->reached = 0;
             count = ((uint64_t)s->counthigh << 32) | s->count;
             DPRINTF("processor %d user timer set to %016llx\n", s->slave_index,
                     count);
             if (s->timer)
                 ptimer_set_count(s->timer, LIMIT_TO_PERIODS(s->limit - count));
         } else {
             // set limit, reset counter
             qemu_irq_lower(s->irq);
             s->limit = val & TIMER_MAX_COUNT32;
             if (s->timer) {
                 if (s->limit == 0) /* free-run */
                     ptimer_set_limit(s->timer,
                                      LIMIT_TO_PERIODS(TIMER_MAX_COUNT32), 1);
                 else
                     ptimer_set_limit(s->timer, LIMIT_TO_PERIODS(s->limit), 1);
             }
         }
         break;
     case TIMER_COUNTER:
         if (slavio_timer_is_user(s)) {
             uint64_t count;

             // set user counter LSW, reset counter
             s->limit = TIMER_MAX_COUNT64;
             s->count = val & TIMER_MAX_COUNT64;
             s->reached = 0;
             count = ((uint64_t)s->counthigh) << 32 | s->count;
             DPRINTF("processor %d user timer set to %016llx\n", s->slave_index,
                     count);
             if (s->timer)
                 ptimer_set_count(s->timer, LIMIT_TO_PERIODS(s->limit - count));
         } else
             DPRINTF("not user timer\n");
         break;
     case TIMER_COUNTER_NORST:
         // set limit without resetting counter
         s->limit = val & TIMER_MAX_COUNT32;
         if (s->timer) {
             if (s->limit == 0)	/* free-run */
                 ptimer_set_limit(s->timer,
                                  LIMIT_TO_PERIODS(TIMER_MAX_COUNT32), 0);
             else
                 ptimer_set_limit(s->timer, LIMIT_TO_PERIODS(s->limit), 0);
         }
         break;
     case TIMER_STATUS:
         if (slavio_timer_is_user(s)) {
             // start/stop user counter
             if ((val & 1) && !s->running) {
                 DPRINTF("processor %d user timer started\n", s->slave_index);
                 if (s->timer)
                     ptimer_run(s->timer, 0);
                 s->running = 1;
             } else if (!(val & 1) && s->running) {
                 DPRINTF("processor %d user timer stopped\n", s->slave_index);
                 if (s->timer)
                     ptimer_stop(s->timer);
                 s->running = 0;
             }
         }
         break;
     case TIMER_MODE:
         if (s->master == NULL) {
             unsigned int i;

             for (i = 0; i < s->num_slaves; i++) {
                 unsigned int processor = 1 << i;

                 // check for a change in timer mode for this processor
                 if ((val & processor) != (s->slave_mode & processor)) {
                     if (val & processor) { // counter -> user timer
                         qemu_irq_lower(s->slave[i]->irq);
                         // counters are always running
                         ptimer_stop(s->slave[i]->timer);
                         s->slave[i]->running = 0;
                         // user timer limit is always the same
                         s->slave[i]->limit = TIMER_MAX_COUNT64;
                         ptimer_set_limit(s->slave[i]->timer,
                                          LIMIT_TO_PERIODS(s->slave[i]->limit),
                                          1);
                         // set this processors user timer bit in config
                         // register
                         s->slave_mode |= processor;
                         DPRINTF("processor %d changed from counter to user "
                                 "timer\n", s->slave[i]->slave_index);
                     } else { // user timer -> counter
                         // stop the user timer if it is running
                         if (s->slave[i]->running)
                             ptimer_stop(s->slave[i]->timer);
                         // start the counter
                         ptimer_run(s->slave[i]->timer, 0);
                         s->slave[i]->running = 1;
                         // clear this processors user timer bit in config
                         // register
                         s->slave_mode &= ~processor;
                         DPRINTF("processor %d changed from user timer to "
                                 "counter\n", s->slave[i]->slave_index);
                     }
                 }
             }
         } else
             DPRINTF("not system timer\n");
         break;
     default:
         DPRINTF("invalid write address " TARGET_FMT_plx "\n", addr);
         break;
     }
 }

 static CPUReadMemoryFunc *slavio_timer_mem_read[3] = {
     NULL,
     NULL,
     slavio_timer_mem_readl,
 };

 static CPUWriteMemoryFunc *slavio_timer_mem_write[3] = {
     NULL,
     NULL,
     slavio_timer_mem_writel,
 };

 static void slavio_timer_save(QEMUFile *f, void *opaque)
 {
     SLAVIO_TIMERState *s = opaque;

     qemu_put_be64s(f, &s->limit);
     qemu_put_be32s(f, &s->count);
     qemu_put_be32s(f, &s->counthigh);
     qemu_put_be32s(f, &s->reached);
     qemu_put_be32s(f, &s->running);
     if (s->timer)
         qemu_put_ptimer(f, s->timer);
 }

 static int slavio_timer_load(QEMUFile *f, void *opaque, int version_id)
 {
     SLAVIO_TIMERState *s = opaque;

     if (version_id != 3)
         return -EINVAL;

     qemu_get_be64s(f, &s->limit);
     qemu_get_be32s(f, &s->count);
     qemu_get_be32s(f, &s->counthigh);
     qemu_get_be32s(f, &s->reached);
     qemu_get_be32s(f, &s->running);
     if (s->timer)
         qemu_get_ptimer(f, s->timer);

     return 0;
 }

 static void slavio_timer_reset(void *opaque)
 {
     SLAVIO_TIMERState *s = opaque;

     s->limit = 0;
     s->count = 0;
     s->reached = 0;
     s->slave_mode = 0;
     if (!s->master || s->slave_index < s->master->num_slaves) {
         ptimer_set_limit(s->timer, LIMIT_TO_PERIODS(TIMER_MAX_COUNT32), 1);
         ptimer_run(s->timer, 0);
     }
     s->running = 1;
     qemu_irq_lower(s->irq);
 }

 static SLAVIO_TIMERState *slavio_timer_init(target_phys_addr_t addr,
                                             qemu_irq irq,
                                             SLAVIO_TIMERState *master,
                                             uint32_t slave_index)
 {
     int slavio_timer_io_memory;
     SLAVIO_TIMERState *s;
     QEMUBH *bh;

     s = qemu_mallocz(sizeof(SLAVIO_TIMERState));
     s->irq = irq;
     s->master = master;
     s->slave_index = slave_index;
     if (!master || slave_index < master->num_slaves) {
         bh = qemu_bh_new(slavio_timer_irq, s);
         s->timer = ptimer_init(bh);
         ptimer_set_period(s->timer, TIMER_PERIOD);
     }

     slavio_timer_io_memory = cpu_register_io_memory(0, slavio_timer_mem_read,
                                                     slavio_timer_mem_write, s);
     if (master)
         cpu_register_physical_memory(addr, CPU_TIMER_SIZE,
                                      slavio_timer_io_memory);
     else
         cpu_register_physical_memory(addr, SYS_TIMER_SIZE,
                                      slavio_timer_io_memory);
     register_savevm("slavio_timer", addr, 3, slavio_timer_save,
                     slavio_timer_load, s);
     qemu_register_reset(slavio_timer_reset, s);
     slavio_timer_reset(s);

     return s;
 }

 void slavio_timer_init_all(target_phys_addr_t base, qemu_irq master_irq,
                            qemu_irq *cpu_irqs, unsigned int num_cpus)
 {
     SLAVIO_TIMERState *master;
     unsigned int i;

     master = slavio_timer_init(base + SYS_TIMER_OFFSET, master_irq, NULL, 0);

     master->num_slaves = num_cpus;

     for (i = 0; i < MAX_CPUS; i++) {
         master->slave[i] = slavio_timer_init(base + (target_phys_addr_t)
                                              CPU_TIMER_OFFSET(i),
                                              cpu_irqs[i], master, i);
     }
 }
	/*
	* QEMU Sparc SLAVIO timer controller emulation
	*
	* Copyright (c) 2003-2005 Fabrice Bellard
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this software and associated documentation files (the "Software"), to deal
	* in the Software without restriction, including without limitation the rights
	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	* copies of the Software, and to permit persons to whom the Software is
	* furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	* THE SOFTWARE.
	*/
	#include "hw.h"
	#include "sun4m.h"
	#include "qemu-timer.h"

	//#define DEBUG_TIMER

	#ifdef DEBUG_TIMER
	#define DPRINTF(fmt, ...) \
	do { printf("TIMER: " fmt , ## __VA_ARGS__); } while (0)
	#else
	#define DPRINTF(fmt, ...) do {} while (0)
	#endif

	/*
	* Registers of hardware timer in sun4m.
	*
	* This is the timer/counter part of chip STP2001 (Slave I/O), also
	* produced as NCR89C105. See
	* http://www.ibiblio.org/pub/historic-linux/early-ports/Sparc/NCR/NCR89C105.txt
	*
	* The 31-bit counter is incremented every 500ns by bit 9. Bits 8..0
	* are zero. Bit 31 is 1 when count has been reached.
	*
	* Per-CPU timers interrupt local CPU, system timer uses normal
	* interrupt routing.
	*
	*/

	#define MAX_CPUS 16

	typedef struct SLAVIO_TIMERState {
	qemu_irq irq;
	ptimer_state *timer;
	uint32_t count, counthigh, reached;
	uint64_t limit;
	// processor only
	uint32_t running;
	struct SLAVIO_TIMERState *master;
	uint32_t slave_index;
	// system only
	uint32_t num_slaves;
	struct SLAVIO_TIMERState *slave[MAX_CPUS];
	uint32_t slave_mode;
	} SLAVIO_TIMERState;

	#define SYS_TIMER_SIZE 0x14
	#define CPU_TIMER_SIZE 0x10

	#define SYS_TIMER_OFFSET 0x10000ULL
	#define CPU_TIMER_OFFSET(cpu) (0x1000ULL * cpu)

	#define TIMER_LIMIT 0
	#define TIMER_COUNTER 1
	#define TIMER_COUNTER_NORST 2
	#define TIMER_STATUS 3
	#define TIMER_MODE 4

	#define TIMER_COUNT_MASK32 0xfffffe00
	#define TIMER_LIMIT_MASK32 0x7fffffff
	#define TIMER_MAX_COUNT64 0x7ffffffffffffe00ULL
	#define TIMER_MAX_COUNT32 0x7ffffe00ULL
	#define TIMER_REACHED 0x80000000
	#define TIMER_PERIOD 500ULL // 500ns
	#define LIMIT_TO_PERIODS(l) ((l) >> 9)
	#define PERIODS_TO_LIMIT(l) ((l) << 9)

	static int slavio_timer_is_user(SLAVIO_TIMERState *s)
	{
	return s->master && (s->master->slave_mode & (1 << s->slave_index));
	}

	// Update count, set irq, update expire_time
	// Convert from ptimer countdown units
	static void slavio_timer_get_out(SLAVIO_TIMERState *s)
	{
	uint64_t count, limit;

	if (s->limit == 0) /* free-run processor or system counter */
	limit = TIMER_MAX_COUNT32;
	else
	limit = s->limit;

	if (s->timer)
	count = limit - PERIODS_TO_LIMIT(ptimer_get_count(s->timer));
	else
	count = 0;

	DPRINTF("get_out: limit %" PRIx64 " count %x%08x\n", s->limit,
	s->counthigh, s->count);
	s->count = count & TIMER_COUNT_MASK32;
	s->counthigh = count >> 32;
	}

	// timer callback
	static void slavio_timer_irq(void *opaque)
	{
	SLAVIO_TIMERState *s = opaque;

	slavio_timer_get_out(s);
	DPRINTF("callback: count %x%08x\n", s->counthigh, s->count);
	s->reached = TIMER_REACHED;
	if (!slavio_timer_is_user(s))
	qemu_irq_raise(s->irq);
	}

	static uint32_t slavio_timer_mem_readl(void *opaque, target_phys_addr_t addr)
	{
	SLAVIO_TIMERState *s = opaque;
	uint32_t saddr, ret;

	saddr = addr >> 2;
	switch (saddr) {
	case TIMER_LIMIT:
	// read limit (system counter mode) or read most signifying
	// part of counter (user mode)
	if (slavio_timer_is_user(s)) {
	// read user timer MSW
	slavio_timer_get_out(s);
	ret = s->counthigh \| s->reached;
	} else {
	// read limit
	// clear irq
	qemu_irq_lower(s->irq);
	s->reached = 0;
	ret = s->limit & TIMER_LIMIT_MASK32;
	}
	break;
	case TIMER_COUNTER:
	// read counter and reached bit (system mode) or read lsbits
	// of counter (user mode)
	slavio_timer_get_out(s);
	if (slavio_timer_is_user(s)) // read user timer LSW
	ret = s->count & TIMER_MAX_COUNT64;
	else // read limit
	ret = (s->count & TIMER_MAX_COUNT32) \| s->reached;
	break;
	case TIMER_STATUS:
	// only available in processor counter/timer
	// read start/stop status
	ret = s->running;
	break;
	case TIMER_MODE:
	// only available in system counter
	// read user/system mode
	ret = s->slave_mode;
	break;
	default:
	DPRINTF("invalid read address " TARGET_FMT_plx "\n", addr);
	ret = 0;
	break;
	}
	DPRINTF("read " TARGET_FMT_plx " = %08x\n", addr, ret);

	return ret;
	}

	static void slavio_timer_mem_writel(void *opaque, target_phys_addr_t addr,
	uint32_t val)
	{
	SLAVIO_TIMERState *s = opaque;
	uint32_t saddr;

	DPRINTF("write " TARGET_FMT_plx " %08x\n", addr, val);
	saddr = addr >> 2;
	switch (saddr) {
	case TIMER_LIMIT:
	if (slavio_timer_is_user(s)) {
	uint64_t count;

	// set user counter MSW, reset counter
	s->limit = TIMER_MAX_COUNT64;
	s->counthigh = val & (TIMER_MAX_COUNT64 >> 32);
	s->reached = 0;
	count = ((uint64_t)s->counthigh << 32) \| s->count;
	DPRINTF("processor %d user timer set to %016llx\n", s->slave_index,
	count);
	if (s->timer)
	ptimer_set_count(s->timer, LIMIT_TO_PERIODS(s->limit - count));
	} else {
	// set limit, reset counter
	qemu_irq_lower(s->irq);
	s->limit = val & TIMER_MAX_COUNT32;
	if (s->timer) {
	if (s->limit == 0) /* free-run */
	ptimer_set_limit(s->timer,
	LIMIT_TO_PERIODS(TIMER_MAX_COUNT32), 1);
	else
	ptimer_set_limit(s->timer, LIMIT_TO_PERIODS(s->limit), 1);
	}
	}
	break;
	case TIMER_COUNTER:
	if (slavio_timer_is_user(s)) {
	uint64_t count;

	// set user counter LSW, reset counter
	s->limit = TIMER_MAX_COUNT64;
	s->count = val & TIMER_MAX_COUNT64;
	s->reached = 0;
	count = ((uint64_t)s->counthigh) << 32 \| s->count;
	DPRINTF("processor %d user timer set to %016llx\n", s->slave_index,
	count);
	if (s->timer)
	ptimer_set_count(s->timer, LIMIT_TO_PERIODS(s->limit - count));
	} else
	DPRINTF("not user timer\n");
	break;
	case TIMER_COUNTER_NORST:
	// set limit without resetting counter
	s->limit = val & TIMER_MAX_COUNT32;
	if (s->timer) {
	if (s->limit == 0) /* free-run */
	ptimer_set_limit(s->timer,
	LIMIT_TO_PERIODS(TIMER_MAX_COUNT32), 0);
	else
	ptimer_set_limit(s->timer, LIMIT_TO_PERIODS(s->limit), 0);
	}
	break;
	case TIMER_STATUS:
	if (slavio_timer_is_user(s)) {
	// start/stop user counter
	if ((val & 1) && !s->running) {
	DPRINTF("processor %d user timer started\n", s->slave_index);
	if (s->timer)
	ptimer_run(s->timer, 0);
	s->running = 1;
	} else if (!(val & 1) && s->running) {
	DPRINTF("processor %d user timer stopped\n", s->slave_index);
	if (s->timer)
	ptimer_stop(s->timer);
	s->running = 0;
	}
	}
	break;
	case TIMER_MODE:
	if (s->master == NULL) {
	unsigned int i;

	for (i = 0; i < s->num_slaves; i++) {
	unsigned int processor = 1 << i;

	// check for a change in timer mode for this processor
	if ((val & processor) != (s->slave_mode & processor)) {
	if (val & processor) { // counter -> user timer
	qemu_irq_lower(s->slave[i]->irq);
	// counters are always running
	ptimer_stop(s->slave[i]->timer);
	s->slave[i]->running = 0;
	// user timer limit is always the same
	s->slave[i]->limit = TIMER_MAX_COUNT64;
	ptimer_set_limit(s->slave[i]->timer,
	LIMIT_TO_PERIODS(s->slave[i]->limit),
	1);
	// set this processors user timer bit in config
	// register
	s->slave_mode \|= processor;
	DPRINTF("processor %d changed from counter to user "
	"timer\n", s->slave[i]->slave_index);
	} else { // user timer -> counter
	// stop the user timer if it is running
	if (s->slave[i]->running)
	ptimer_stop(s->slave[i]->timer);
	// start the counter
	ptimer_run(s->slave[i]->timer, 0);
	s->slave[i]->running = 1;
	// clear this processors user timer bit in config
	// register
	s->slave_mode &= ~processor;
	DPRINTF("processor %d changed from user timer to "
	"counter\n", s->slave[i]->slave_index);
	}
	}
	}
	} else
	DPRINTF("not system timer\n");
	break;
	default:
	DPRINTF("invalid write address " TARGET_FMT_plx "\n", addr);
	break;
	}
	}

	static CPUReadMemoryFunc *slavio_timer_mem_read[3] = {
	NULL,
	NULL,
	slavio_timer_mem_readl,
	};

	static CPUWriteMemoryFunc *slavio_timer_mem_write[3] = {
	NULL,
	NULL,
	slavio_timer_mem_writel,
	};

	static void slavio_timer_save(QEMUFile f, void opaque)
	{
	SLAVIO_TIMERState *s = opaque;

	qemu_put_be64s(f, &s->limit);
	qemu_put_be32s(f, &s->count);
	qemu_put_be32s(f, &s->counthigh);
	qemu_put_be32s(f, &s->reached);
	qemu_put_be32s(f, &s->running);
	if (s->timer)
	qemu_put_ptimer(f, s->timer);
	}

	static int slavio_timer_load(QEMUFile f, void opaque, int version_id)
	{
	SLAVIO_TIMERState *s = opaque;

	if (version_id != 3)
	return -EINVAL;

	qemu_get_be64s(f, &s->limit);
	qemu_get_be32s(f, &s->count);
	qemu_get_be32s(f, &s->counthigh);
	qemu_get_be32s(f, &s->reached);
	qemu_get_be32s(f, &s->running);
	if (s->timer)
	qemu_get_ptimer(f, s->timer);

	return 0;
	}

	static void slavio_timer_reset(void *opaque)
	{
	SLAVIO_TIMERState *s = opaque;

	s->limit = 0;
	s->count = 0;
	s->reached = 0;
	s->slave_mode = 0;
	if (!s->master \|\| s->slave_index < s->master->num_slaves) {
	ptimer_set_limit(s->timer, LIMIT_TO_PERIODS(TIMER_MAX_COUNT32), 1);
	ptimer_run(s->timer, 0);
	}
	s->running = 1;
	qemu_irq_lower(s->irq);
	}

	static SLAVIO_TIMERState *slavio_timer_init(target_phys_addr_t addr,
	qemu_irq irq,
	SLAVIO_TIMERState *master,
	uint32_t slave_index)
	{
	int slavio_timer_io_memory;
	SLAVIO_TIMERState *s;
	QEMUBH *bh;

	s = qemu_mallocz(sizeof(SLAVIO_TIMERState));
	s->irq = irq;
	s->master = master;
	s->slave_index = slave_index;
	if (!master \|\| slave_index < master->num_slaves) {
	bh = qemu_bh_new(slavio_timer_irq, s);
	s->timer = ptimer_init(bh);
	ptimer_set_period(s->timer, TIMER_PERIOD);
	}

	slavio_timer_io_memory = cpu_register_io_memory(0, slavio_timer_mem_read,
	slavio_timer_mem_write, s);
	if (master)
	cpu_register_physical_memory(addr, CPU_TIMER_SIZE,
	slavio_timer_io_memory);
	else
	cpu_register_physical_memory(addr, SYS_TIMER_SIZE,
	slavio_timer_io_memory);
	register_savevm("slavio_timer", addr, 3, slavio_timer_save,
	slavio_timer_load, s);
	qemu_register_reset(slavio_timer_reset, s);
	slavio_timer_reset(s);

	return s;
	}

	void slavio_timer_init_all(target_phys_addr_t base, qemu_irq master_irq,
	qemu_irq *cpu_irqs, unsigned int num_cpus)
	{
	SLAVIO_TIMERState *master;
	unsigned int i;

	master = slavio_timer_init(base + SYS_TIMER_OFFSET, master_irq, NULL, 0);

	master->num_slaves = num_cpus;

	for (i = 0; i < MAX_CPUS; i++) {
	master->slave[i] = slavio_timer_init(base + (target_phys_addr_t)
	CPU_TIMER_OFFSET(i),
	cpu_irqs[i], master, i);
	}
	}