hw/timer/cmsdk-apb-timer.c - qemu - Git at Google

 /*
  * ARM CMSDK APB timer emulation
  *
  * Copyright (c) 2017 Linaro Limited
  * Written by Peter Maydell
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License version 2 or
  *  (at your option) any later version.
  */

 /* This is a model of the "APB timer" which is part of the Cortex-M
  * System Design Kit (CMSDK) and documented in the Cortex-M System
  * Design Kit Technical Reference Manual (ARM DDI0479C):
  * https://developer.arm.com/products/system-design/system-design-kits/cortex-m-system-design-kit
  *
  * The hardware has an EXTIN input wire, which can be configured
  * by the guest to act either as a 'timer enable' (timer does not run
  * when EXTIN is low), or as a 'timer clock' (timer runs at frequency
  * of EXTIN clock, not PCLK frequency). We don't model this.
  *
  * The documentation is not very clear about the exact behaviour;
  * we choose to implement that the interrupt is triggered when
  * the counter goes from 1 to 0, that the counter then holds at 0
  * for one clock cycle before reloading from the RELOAD register,
  * and that if the RELOAD register is 0 this does not cause an
  * interrupt (as there is no further 1->0 transition).
  */

 #include "qemu/osdep.h"
 #include "qemu/log.h"
 #include "qemu/module.h"
 #include "qapi/error.h"
 #include "trace.h"
 #include "hw/sysbus.h"
 #include "hw/irq.h"
 #include "hw/registerfields.h"
 #include "hw/qdev-clock.h"
 #include "hw/timer/cmsdk-apb-timer.h"
 #include "migration/vmstate.h"

 REG32(CTRL, 0)
     FIELD(CTRL, EN, 0, 1)
     FIELD(CTRL, SELEXTEN, 1, 1)
     FIELD(CTRL, SELEXTCLK, 2, 1)
     FIELD(CTRL, IRQEN, 3, 1)
 REG32(VALUE, 4)
 REG32(RELOAD, 8)
 REG32(INTSTATUS, 0xc)
     FIELD(INTSTATUS, IRQ, 0, 1)
 REG32(PID4, 0xFD0)
 REG32(PID5, 0xFD4)
 REG32(PID6, 0xFD8)
 REG32(PID7, 0xFDC)
 REG32(PID0, 0xFE0)
 REG32(PID1, 0xFE4)
 REG32(PID2, 0xFE8)
 REG32(PID3, 0xFEC)
 REG32(CID0, 0xFF0)
 REG32(CID1, 0xFF4)
 REG32(CID2, 0xFF8)
 REG32(CID3, 0xFFC)

 /* PID/CID values */
 static const int timer_id[] = {
     0x04, 0x00, 0x00, 0x00, /* PID4..PID7 */
     0x22, 0xb8, 0x1b, 0x00, /* PID0..PID3 */
     0x0d, 0xf0, 0x05, 0xb1, /* CID0..CID3 */
 };

 static void cmsdk_apb_timer_update(CMSDKAPBTimer *s)
 {
     qemu_set_irq(s->timerint, !!(s->intstatus & R_INTSTATUS_IRQ_MASK));
 }

 static uint64_t cmsdk_apb_timer_read(void *opaque, hwaddr offset, unsigned size)
 {
     CMSDKAPBTimer *s = CMSDK_APB_TIMER(opaque);
     uint64_t r;

     switch (offset) {
     case A_CTRL:
         r = s->ctrl;
         break;
     case A_VALUE:
         r = ptimer_get_count(s->timer);
         break;
     case A_RELOAD:
         r = ptimer_get_limit(s->timer);
         break;
     case A_INTSTATUS:
         r = s->intstatus;
         break;
     case A_PID4 ... A_CID3:
         r = timer_id[(offset - A_PID4) / 4];
         break;
     default:
         qemu_log_mask(LOG_GUEST_ERROR,
                       "CMSDK APB timer read: bad offset %x\n", (int) offset);
         r = 0;
         break;
     }
     trace_cmsdk_apb_timer_read(offset, r, size);
     return r;
 }

 static void cmsdk_apb_timer_write(void *opaque, hwaddr offset, uint64_t value,
                                   unsigned size)
 {
     CMSDKAPBTimer *s = CMSDK_APB_TIMER(opaque);

     trace_cmsdk_apb_timer_write(offset, value, size);

     switch (offset) {
     case A_CTRL:
         if (value & 6) {
             /* Bits [1] and [2] enable using EXTIN as either clock or
              * an enable line. We don't model this.
              */
             qemu_log_mask(LOG_UNIMP,
                           "CMSDK APB timer: EXTIN input not supported\n");
         }
         s->ctrl = value & 0xf;
         ptimer_transaction_begin(s->timer);
         if (s->ctrl & R_CTRL_EN_MASK) {
             ptimer_run(s->timer, ptimer_get_limit(s->timer) == 0);
         } else {
             ptimer_stop(s->timer);
         }
         ptimer_transaction_commit(s->timer);
         break;
     case A_RELOAD:
         /* Writing to reload also sets the current timer value */
         ptimer_transaction_begin(s->timer);
         if (!value) {
             ptimer_stop(s->timer);
         }
         ptimer_set_limit(s->timer, value, 1);
         if (value && (s->ctrl & R_CTRL_EN_MASK)) {
             /*
              * Make sure timer is running (it might have stopped if this
              * was an expired one-shot timer)
              */
             ptimer_run(s->timer, 0);
         }
         ptimer_transaction_commit(s->timer);
         break;
     case A_VALUE:
         ptimer_transaction_begin(s->timer);
         if (!value && !ptimer_get_limit(s->timer)) {
             ptimer_stop(s->timer);
         }
         ptimer_set_count(s->timer, value);
         if (value && (s->ctrl & R_CTRL_EN_MASK)) {
             ptimer_run(s->timer, ptimer_get_limit(s->timer) == 0);
         }
         ptimer_transaction_commit(s->timer);
         break;
     case A_INTSTATUS:
         /* Just one bit, which is W1C. */
         value &= 1;
         s->intstatus &= ~value;
         cmsdk_apb_timer_update(s);
         break;
     case A_PID4 ... A_CID3:
         qemu_log_mask(LOG_GUEST_ERROR,
                       "CMSDK APB timer write: write to RO offset 0x%x\n",
                       (int)offset);
         break;
     default:
         qemu_log_mask(LOG_GUEST_ERROR,
                       "CMSDK APB timer write: bad offset 0x%x\n", (int) offset);
         break;
     }
 }

 static const MemoryRegionOps cmsdk_apb_timer_ops = {
     .read = cmsdk_apb_timer_read,
     .write = cmsdk_apb_timer_write,
     .endianness = DEVICE_LITTLE_ENDIAN,
 };

 static void cmsdk_apb_timer_tick(void *opaque)
 {
     CMSDKAPBTimer *s = CMSDK_APB_TIMER(opaque);

     if (s->ctrl & R_CTRL_IRQEN_MASK) {
         s->intstatus |= R_INTSTATUS_IRQ_MASK;
         cmsdk_apb_timer_update(s);
     }
 }

 static void cmsdk_apb_timer_reset(DeviceState *dev)
 {
     CMSDKAPBTimer *s = CMSDK_APB_TIMER(dev);

     trace_cmsdk_apb_timer_reset();
     s->ctrl = 0;
     s->intstatus = 0;
     ptimer_transaction_begin(s->timer);
     ptimer_stop(s->timer);
     /* Set the limit and the count */
     ptimer_set_limit(s->timer, 0, 1);
     ptimer_transaction_commit(s->timer);
 }

 static void cmsdk_apb_timer_clk_update(void *opaque, ClockEvent event)
 {
     CMSDKAPBTimer *s = CMSDK_APB_TIMER(opaque);

     ptimer_transaction_begin(s->timer);
     ptimer_set_period_from_clock(s->timer, s->pclk, 1);
     ptimer_transaction_commit(s->timer);
 }

 static void cmsdk_apb_timer_init(Object *obj)
 {
     SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
     CMSDKAPBTimer *s = CMSDK_APB_TIMER(obj);

     memory_region_init_io(&s->iomem, obj, &cmsdk_apb_timer_ops,
                           s, "cmsdk-apb-timer", 0x1000);
     sysbus_init_mmio(sbd, &s->iomem);
     sysbus_init_irq(sbd, &s->timerint);
     s->pclk = qdev_init_clock_in(DEVICE(s), "pclk",
                                  cmsdk_apb_timer_clk_update, s, ClockUpdate);
 }

 static void cmsdk_apb_timer_realize(DeviceState *dev, Error **errp)
 {
     CMSDKAPBTimer *s = CMSDK_APB_TIMER(dev);

     if (!clock_has_source(s->pclk)) {
         error_setg(errp, "CMSDK APB timer: pclk clock must be connected");
         return;
     }

     s->timer = ptimer_init(cmsdk_apb_timer_tick, s,
                            PTIMER_POLICY_WRAP_AFTER_ONE_PERIOD |
                            PTIMER_POLICY_TRIGGER_ONLY_ON_DECREMENT |
                            PTIMER_POLICY_NO_IMMEDIATE_RELOAD |
                            PTIMER_POLICY_NO_COUNTER_ROUND_DOWN);

     ptimer_transaction_begin(s->timer);
     ptimer_set_period_from_clock(s->timer, s->pclk, 1);
     ptimer_transaction_commit(s->timer);
 }

 static const VMStateDescription cmsdk_apb_timer_vmstate = {
     .name = "cmsdk-apb-timer",
     .version_id = 2,
     .minimum_version_id = 2,
     .fields = (VMStateField[]) {
         VMSTATE_PTIMER(timer, CMSDKAPBTimer),
         VMSTATE_CLOCK(pclk, CMSDKAPBTimer),
         VMSTATE_UINT32(ctrl, CMSDKAPBTimer),
         VMSTATE_UINT32(value, CMSDKAPBTimer),
         VMSTATE_UINT32(reload, CMSDKAPBTimer),
         VMSTATE_UINT32(intstatus, CMSDKAPBTimer),
         VMSTATE_END_OF_LIST()
     }
 };

 static void cmsdk_apb_timer_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);

     dc->realize = cmsdk_apb_timer_realize;
     dc->vmsd = &cmsdk_apb_timer_vmstate;
     dc->reset = cmsdk_apb_timer_reset;
 }

 static const TypeInfo cmsdk_apb_timer_info = {
     .name = TYPE_CMSDK_APB_TIMER,
     .parent = TYPE_SYS_BUS_DEVICE,
     .instance_size = sizeof(CMSDKAPBTimer),
     .instance_init = cmsdk_apb_timer_init,
     .class_init = cmsdk_apb_timer_class_init,
 };

 static void cmsdk_apb_timer_register_types(void)
 {
     type_register_static(&cmsdk_apb_timer_info);
 }

 type_init(cmsdk_apb_timer_register_types);
	/*
	* ARM CMSDK APB timer emulation
	*
	* Copyright (c) 2017 Linaro Limited
	* Written by Peter Maydell
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 or
	* (at your option) any later version.
	*/

	/* This is a model of the "APB timer" which is part of the Cortex-M
	* System Design Kit (CMSDK) and documented in the Cortex-M System
	* Design Kit Technical Reference Manual (ARM DDI0479C):
	* https://developer.arm.com/products/system-design/system-design-kits/cortex-m-system-design-kit
	*
	* The hardware has an EXTIN input wire, which can be configured
	* by the guest to act either as a 'timer enable' (timer does not run
	* when EXTIN is low), or as a 'timer clock' (timer runs at frequency
	* of EXTIN clock, not PCLK frequency). We don't model this.
	*
	* The documentation is not very clear about the exact behaviour;
	* we choose to implement that the interrupt is triggered when
	* the counter goes from 1 to 0, that the counter then holds at 0
	* for one clock cycle before reloading from the RELOAD register,
	* and that if the RELOAD register is 0 this does not cause an
	* interrupt (as there is no further 1->0 transition).
	*/

	#include "qemu/osdep.h"
	#include "qemu/log.h"
	#include "qemu/module.h"
	#include "qapi/error.h"
	#include "trace.h"
	#include "hw/sysbus.h"
	#include "hw/irq.h"
	#include "hw/registerfields.h"
	#include "hw/qdev-clock.h"
	#include "hw/timer/cmsdk-apb-timer.h"
	#include "migration/vmstate.h"

	REG32(CTRL, 0)
	FIELD(CTRL, EN, 0, 1)
	FIELD(CTRL, SELEXTEN, 1, 1)
	FIELD(CTRL, SELEXTCLK, 2, 1)
	FIELD(CTRL, IRQEN, 3, 1)
	REG32(VALUE, 4)
	REG32(RELOAD, 8)
	REG32(INTSTATUS, 0xc)
	FIELD(INTSTATUS, IRQ, 0, 1)
	REG32(PID4, 0xFD0)
	REG32(PID5, 0xFD4)
	REG32(PID6, 0xFD8)
	REG32(PID7, 0xFDC)
	REG32(PID0, 0xFE0)
	REG32(PID1, 0xFE4)
	REG32(PID2, 0xFE8)
	REG32(PID3, 0xFEC)
	REG32(CID0, 0xFF0)
	REG32(CID1, 0xFF4)
	REG32(CID2, 0xFF8)
	REG32(CID3, 0xFFC)

	/* PID/CID values */
	static const int timer_id[] = {
	0x04, 0x00, 0x00, 0x00, /* PID4..PID7 */
	0x22, 0xb8, 0x1b, 0x00, /* PID0..PID3 */
	0x0d, 0xf0, 0x05, 0xb1, /* CID0..CID3 */
	};

	static void cmsdk_apb_timer_update(CMSDKAPBTimer *s)
	{
	qemu_set_irq(s->timerint, !!(s->intstatus & R_INTSTATUS_IRQ_MASK));
	}

	static uint64_t cmsdk_apb_timer_read(void *opaque, hwaddr offset, unsigned size)
	{
	CMSDKAPBTimer *s = CMSDK_APB_TIMER(opaque);
	uint64_t r;

	switch (offset) {
	case A_CTRL:
	r = s->ctrl;
	break;
	case A_VALUE:
	r = ptimer_get_count(s->timer);
	break;
	case A_RELOAD:
	r = ptimer_get_limit(s->timer);
	break;
	case A_INTSTATUS:
	r = s->intstatus;
	break;
	case A_PID4 ... A_CID3:
	r = timer_id[(offset - A_PID4) / 4];
	break;
	default:
	qemu_log_mask(LOG_GUEST_ERROR,
	"CMSDK APB timer read: bad offset %x\n", (int) offset);
	r = 0;
	break;
	}
	trace_cmsdk_apb_timer_read(offset, r, size);
	return r;
	}

	static void cmsdk_apb_timer_write(void *opaque, hwaddr offset, uint64_t value,
	unsigned size)
	{
	CMSDKAPBTimer *s = CMSDK_APB_TIMER(opaque);

	trace_cmsdk_apb_timer_write(offset, value, size);

	switch (offset) {
	case A_CTRL:
	if (value & 6) {
	/* Bits [1] and [2] enable using EXTIN as either clock or
	* an enable line. We don't model this.
	*/
	qemu_log_mask(LOG_UNIMP,
	"CMSDK APB timer: EXTIN input not supported\n");
	}
	s->ctrl = value & 0xf;
	ptimer_transaction_begin(s->timer);
	if (s->ctrl & R_CTRL_EN_MASK) {
	ptimer_run(s->timer, ptimer_get_limit(s->timer) == 0);
	} else {
	ptimer_stop(s->timer);
	}
	ptimer_transaction_commit(s->timer);
	break;
	case A_RELOAD:
	/* Writing to reload also sets the current timer value */
	ptimer_transaction_begin(s->timer);
	if (!value) {
	ptimer_stop(s->timer);
	}
	ptimer_set_limit(s->timer, value, 1);
	if (value && (s->ctrl & R_CTRL_EN_MASK)) {
	/*
	* Make sure timer is running (it might have stopped if this
	* was an expired one-shot timer)
	*/
	ptimer_run(s->timer, 0);
	}
	ptimer_transaction_commit(s->timer);
	break;
	case A_VALUE:
	ptimer_transaction_begin(s->timer);
	if (!value && !ptimer_get_limit(s->timer)) {
	ptimer_stop(s->timer);
	}
	ptimer_set_count(s->timer, value);
	if (value && (s->ctrl & R_CTRL_EN_MASK)) {
	ptimer_run(s->timer, ptimer_get_limit(s->timer) == 0);
	}
	ptimer_transaction_commit(s->timer);
	break;
	case A_INTSTATUS:
	/* Just one bit, which is W1C. */
	value &= 1;
	s->intstatus &= ~value;
	cmsdk_apb_timer_update(s);
	break;
	case A_PID4 ... A_CID3:
	qemu_log_mask(LOG_GUEST_ERROR,
	"CMSDK APB timer write: write to RO offset 0x%x\n",
	(int)offset);
	break;
	default:
	qemu_log_mask(LOG_GUEST_ERROR,
	"CMSDK APB timer write: bad offset 0x%x\n", (int) offset);
	break;
	}
	}

	static const MemoryRegionOps cmsdk_apb_timer_ops = {
	.read = cmsdk_apb_timer_read,
	.write = cmsdk_apb_timer_write,
	.endianness = DEVICE_LITTLE_ENDIAN,
	};

	static void cmsdk_apb_timer_tick(void *opaque)
	{
	CMSDKAPBTimer *s = CMSDK_APB_TIMER(opaque);

	if (s->ctrl & R_CTRL_IRQEN_MASK) {
	s->intstatus \|= R_INTSTATUS_IRQ_MASK;
	cmsdk_apb_timer_update(s);
	}
	}

	static void cmsdk_apb_timer_reset(DeviceState *dev)
	{
	CMSDKAPBTimer *s = CMSDK_APB_TIMER(dev);

	trace_cmsdk_apb_timer_reset();
	s->ctrl = 0;
	s->intstatus = 0;
	ptimer_transaction_begin(s->timer);
	ptimer_stop(s->timer);
	/* Set the limit and the count */
	ptimer_set_limit(s->timer, 0, 1);
	ptimer_transaction_commit(s->timer);
	}

	static void cmsdk_apb_timer_clk_update(void *opaque, ClockEvent event)
	{
	CMSDKAPBTimer *s = CMSDK_APB_TIMER(opaque);

	ptimer_transaction_begin(s->timer);
	ptimer_set_period_from_clock(s->timer, s->pclk, 1);
	ptimer_transaction_commit(s->timer);
	}

	static void cmsdk_apb_timer_init(Object *obj)
	{
	SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
	CMSDKAPBTimer *s = CMSDK_APB_TIMER(obj);

	memory_region_init_io(&s->iomem, obj, &cmsdk_apb_timer_ops,
	s, "cmsdk-apb-timer", 0x1000);
	sysbus_init_mmio(sbd, &s->iomem);
	sysbus_init_irq(sbd, &s->timerint);
	s->pclk = qdev_init_clock_in(DEVICE(s), "pclk",
	cmsdk_apb_timer_clk_update, s, ClockUpdate);
	}

	static void cmsdk_apb_timer_realize(DeviceState dev, Error *errp)
	{
	CMSDKAPBTimer *s = CMSDK_APB_TIMER(dev);

	if (!clock_has_source(s->pclk)) {
	error_setg(errp, "CMSDK APB timer: pclk clock must be connected");
	return;
	}

	s->timer = ptimer_init(cmsdk_apb_timer_tick, s,
	PTIMER_POLICY_WRAP_AFTER_ONE_PERIOD \|
	PTIMER_POLICY_TRIGGER_ONLY_ON_DECREMENT \|
	PTIMER_POLICY_NO_IMMEDIATE_RELOAD \|
	PTIMER_POLICY_NO_COUNTER_ROUND_DOWN);

	ptimer_transaction_begin(s->timer);
	ptimer_set_period_from_clock(s->timer, s->pclk, 1);
	ptimer_transaction_commit(s->timer);
	}

	static const VMStateDescription cmsdk_apb_timer_vmstate = {
	.name = "cmsdk-apb-timer",
	.version_id = 2,
	.minimum_version_id = 2,
	.fields = (VMStateField[]) {
	VMSTATE_PTIMER(timer, CMSDKAPBTimer),
	VMSTATE_CLOCK(pclk, CMSDKAPBTimer),
	VMSTATE_UINT32(ctrl, CMSDKAPBTimer),
	VMSTATE_UINT32(value, CMSDKAPBTimer),
	VMSTATE_UINT32(reload, CMSDKAPBTimer),
	VMSTATE_UINT32(intstatus, CMSDKAPBTimer),
	VMSTATE_END_OF_LIST()
	}
	};

	static void cmsdk_apb_timer_class_init(ObjectClass klass, void data)
	{
	DeviceClass *dc = DEVICE_CLASS(klass);

	dc->realize = cmsdk_apb_timer_realize;
	dc->vmsd = &cmsdk_apb_timer_vmstate;
	dc->reset = cmsdk_apb_timer_reset;
	}

	static const TypeInfo cmsdk_apb_timer_info = {
	.name = TYPE_CMSDK_APB_TIMER,
	.parent = TYPE_SYS_BUS_DEVICE,
	.instance_size = sizeof(CMSDKAPBTimer),
	.instance_init = cmsdk_apb_timer_init,
	.class_init = cmsdk_apb_timer_class_init,
	};

	static void cmsdk_apb_timer_register_types(void)
	{
	type_register_static(&cmsdk_apb_timer_info);
	}

	type_init(cmsdk_apb_timer_register_types);