target/nios2/cpu.c - qemu - Git at Google

 /*
  * QEMU Nios II CPU
  *
  * Copyright (c) 2012 Chris Wulff <crwulff@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with this library; if not, see
  * <http://www.gnu.org/licenses/lgpl-2.1.html>
  */

 #include "qemu/osdep.h"
 #include "qemu/module.h"
 #include "qapi/error.h"
 #include "cpu.h"
 #include "exec/log.h"
 #include "exec/gdbstub.h"
 #include "hw/qdev-properties.h"

 static void nios2_cpu_set_pc(CPUState *cs, vaddr value)
 {
     Nios2CPU *cpu = NIOS2_CPU(cs);
     CPUNios2State *env = &cpu->env;

     env->pc = value;
 }

 static vaddr nios2_cpu_get_pc(CPUState *cs)
 {
     Nios2CPU *cpu = NIOS2_CPU(cs);
     CPUNios2State *env = &cpu->env;

     return env->pc;
 }

 static void nios2_restore_state_to_opc(CPUState *cs,
                                        const TranslationBlock *tb,
                                        const uint64_t *data)
 {
     Nios2CPU *cpu = NIOS2_CPU(cs);
     CPUNios2State *env = &cpu->env;

     env->pc = data[0];
 }

 static bool nios2_cpu_has_work(CPUState *cs)
 {
     return cs->interrupt_request & CPU_INTERRUPT_HARD;
 }

 static void nios2_cpu_reset_hold(Object *obj)
 {
     CPUState *cs = CPU(obj);
     Nios2CPU *cpu = NIOS2_CPU(cs);
     Nios2CPUClass *ncc = NIOS2_CPU_GET_CLASS(cpu);
     CPUNios2State *env = &cpu->env;

     if (ncc->parent_phases.hold) {
         ncc->parent_phases.hold(obj);
     }

     memset(env->ctrl, 0, sizeof(env->ctrl));
     env->pc = cpu->reset_addr;

 #if defined(CONFIG_USER_ONLY)
     /* Start in user mode with interrupts enabled. */
     env->ctrl[CR_STATUS] = CR_STATUS_RSIE | CR_STATUS_U | CR_STATUS_PIE;
     memset(env->regs, 0, sizeof(env->regs));
 #else
     env->ctrl[CR_STATUS] = CR_STATUS_RSIE;
     nios2_update_crs(env);
     memset(env->shadow_regs, 0, sizeof(env->shadow_regs));
 #endif
 }

 #ifndef CONFIG_USER_ONLY
 static void eic_set_irq(void *opaque, int irq, int level)
 {
     Nios2CPU *cpu = opaque;
     CPUState *cs = CPU(cpu);

     if (level) {
         cpu_interrupt(cs, CPU_INTERRUPT_HARD);
     } else {
         cpu_reset_interrupt(cs, CPU_INTERRUPT_HARD);
     }
 }

 static void iic_set_irq(void *opaque, int irq, int level)
 {
     Nios2CPU *cpu = opaque;
     CPUNios2State *env = &cpu->env;
     CPUState *cs = CPU(cpu);

     env->ctrl[CR_IPENDING] = deposit32(env->ctrl[CR_IPENDING], irq, 1, !!level);

     if (env->ctrl[CR_IPENDING]) {
         cpu_interrupt(cs, CPU_INTERRUPT_HARD);
     } else {
         cpu_reset_interrupt(cs, CPU_INTERRUPT_HARD);
     }
 }
 #endif

 static void nios2_cpu_initfn(Object *obj)
 {
     Nios2CPU *cpu = NIOS2_CPU(obj);

     cpu_set_cpustate_pointers(cpu);

 #if !defined(CONFIG_USER_ONLY)
     mmu_init(&cpu->env);
 #endif
 }

 static ObjectClass *nios2_cpu_class_by_name(const char *cpu_model)
 {
     return object_class_by_name(TYPE_NIOS2_CPU);
 }

 static void realize_cr_status(CPUState *cs)
 {
     Nios2CPU *cpu = NIOS2_CPU(cs);

     /* Begin with all fields of all registers are reserved. */
     memset(cpu->cr_state, 0, sizeof(cpu->cr_state));

     /*
      * The combination of writable and readonly is the set of all
      * non-reserved fields.  We apply writable as a mask to bits,
      * and merge in existing readonly bits, before storing.
      */
 #define WR_REG(C)       cpu->cr_state[C].writable = -1
 #define RO_REG(C)       cpu->cr_state[C].readonly = -1
 #define WR_FIELD(C, F)  cpu->cr_state[C].writable |= R_##C##_##F##_MASK
 #define RO_FIELD(C, F)  cpu->cr_state[C].readonly |= R_##C##_##F##_MASK

     WR_FIELD(CR_STATUS, PIE);
     WR_REG(CR_ESTATUS);
     WR_REG(CR_BSTATUS);
     RO_REG(CR_CPUID);
     RO_REG(CR_EXCEPTION);
     WR_REG(CR_BADADDR);

     if (cpu->eic_present) {
         WR_FIELD(CR_STATUS, RSIE);
         RO_FIELD(CR_STATUS, NMI);
         WR_FIELD(CR_STATUS, PRS);
         RO_FIELD(CR_STATUS, CRS);
         WR_FIELD(CR_STATUS, IL);
         WR_FIELD(CR_STATUS, IH);
     } else {
         RO_FIELD(CR_STATUS, RSIE);
         WR_REG(CR_IENABLE);
         RO_REG(CR_IPENDING);
     }

     if (cpu->mmu_present) {
         WR_FIELD(CR_STATUS, U);
         WR_FIELD(CR_STATUS, EH);

         WR_FIELD(CR_PTEADDR, VPN);
         WR_FIELD(CR_PTEADDR, PTBASE);

         RO_FIELD(CR_TLBMISC, D);
         RO_FIELD(CR_TLBMISC, PERM);
         RO_FIELD(CR_TLBMISC, BAD);
         RO_FIELD(CR_TLBMISC, DBL);
         WR_FIELD(CR_TLBMISC, PID);
         WR_FIELD(CR_TLBMISC, WE);
         WR_FIELD(CR_TLBMISC, RD);
         WR_FIELD(CR_TLBMISC, WAY);

         WR_REG(CR_TLBACC);
     }

     /*
      * TODO: ECC (config, eccinj) and MPU (config, mpubase, mpuacc) are
      * unimplemented, so their corresponding control regs remain reserved.
      */

 #undef WR_REG
 #undef RO_REG
 #undef WR_FIELD
 #undef RO_FIELD
 }

 static void nios2_cpu_realizefn(DeviceState *dev, Error **errp)
 {
     CPUState *cs = CPU(dev);
     Nios2CPU *cpu = NIOS2_CPU(cs);
     Nios2CPUClass *ncc = NIOS2_CPU_GET_CLASS(dev);
     Error *local_err = NULL;

 #ifndef CONFIG_USER_ONLY
     if (cpu->eic_present) {
         qdev_init_gpio_in_named(DEVICE(cpu), eic_set_irq, "EIC", 1);
     } else {
         qdev_init_gpio_in_named(DEVICE(cpu), iic_set_irq, "IRQ", 32);
     }
 #endif

     cpu_exec_realizefn(cs, &local_err);
     if (local_err != NULL) {
         error_propagate(errp, local_err);
         return;
     }

     realize_cr_status(cs);
     qemu_init_vcpu(cs);
     cpu_reset(cs);

     /* We have reserved storage for cpuid; might as well use it. */
     cpu->env.ctrl[CR_CPUID] = cs->cpu_index;

     ncc->parent_realize(dev, errp);
 }

 #ifndef CONFIG_USER_ONLY
 static bool eic_take_interrupt(Nios2CPU *cpu)
 {
     CPUNios2State *env = &cpu->env;
     const uint32_t status = env->ctrl[CR_STATUS];

     if (cpu->rnmi) {
         return !(status & CR_STATUS_NMI);
     }
     if (!(status & CR_STATUS_PIE)) {
         return false;
     }
     if (cpu->ril <= FIELD_EX32(status, CR_STATUS, IL)) {
         return false;
     }
     if (cpu->rrs != FIELD_EX32(status, CR_STATUS, CRS)) {
         return true;
     }
     return status & CR_STATUS_RSIE;
 }

 static bool iic_take_interrupt(Nios2CPU *cpu)
 {
     CPUNios2State *env = &cpu->env;

     if (!(env->ctrl[CR_STATUS] & CR_STATUS_PIE)) {
         return false;
     }
     return env->ctrl[CR_IPENDING] & env->ctrl[CR_IENABLE];
 }

 static bool nios2_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
 {
     Nios2CPU *cpu = NIOS2_CPU(cs);

     if (interrupt_request & CPU_INTERRUPT_HARD) {
         if (cpu->eic_present
             ? eic_take_interrupt(cpu)
             : iic_take_interrupt(cpu)) {
             cs->exception_index = EXCP_IRQ;
             nios2_cpu_do_interrupt(cs);
             return true;
         }
     }
     return false;
 }
 #endif /* !CONFIG_USER_ONLY */

 static void nios2_cpu_disas_set_info(CPUState *cpu, disassemble_info *info)
 {
     /* NOTE: NiosII R2 is not supported yet. */
     info->mach = bfd_arch_nios2;
     info->print_insn = print_insn_nios2;
 }

 static int nios2_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     Nios2CPU *cpu = NIOS2_CPU(cs);
     CPUNios2State *env = &cpu->env;
     uint32_t val;

     if (n < 32) {          /* GP regs */
         val = env->regs[n];
     } else if (n == 32) {    /* PC */
         val = env->pc;
     } else if (n < 49) {     /* Status regs */
         unsigned cr = n - 33;
         if (nios2_cr_reserved(&cpu->cr_state[cr])) {
             val = 0;
         } else {
             val = env->ctrl[n - 33];
         }
     } else {
         /* Invalid regs */
         return 0;
     }

     return gdb_get_reg32(mem_buf, val);
 }

 static int nios2_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
 {
     Nios2CPU *cpu = NIOS2_CPU(cs);
     CPUClass *cc = CPU_GET_CLASS(cs);
     CPUNios2State *env = &cpu->env;
     uint32_t val;

     if (n > cc->gdb_num_core_regs) {
         return 0;
     }
     val = ldl_p(mem_buf);

     if (n < 32) {            /* GP regs */
         env->regs[n] = val;
     } else if (n == 32) {    /* PC */
         env->pc = val;
     } else if (n < 49) {     /* Status regs */
         unsigned cr = n - 33;
         /* ??? Maybe allow the debugger to write to readonly fields. */
         val &= cpu->cr_state[cr].writable;
         val |= cpu->cr_state[cr].readonly & env->ctrl[cr];
         env->ctrl[cr] = val;
     } else {
         g_assert_not_reached();
     }

     return 4;
 }

 static Property nios2_properties[] = {
     DEFINE_PROP_BOOL("diverr_present", Nios2CPU, diverr_present, true),
     DEFINE_PROP_BOOL("mmu_present", Nios2CPU, mmu_present, true),
     /* ALTR,pid-num-bits */
     DEFINE_PROP_UINT32("mmu_pid_num_bits", Nios2CPU, pid_num_bits, 8),
     /* ALTR,tlb-num-ways */
     DEFINE_PROP_UINT32("mmu_tlb_num_ways", Nios2CPU, tlb_num_ways, 16),
     /* ALTR,tlb-num-entries */
     DEFINE_PROP_UINT32("mmu_pid_num_entries", Nios2CPU, tlb_num_entries, 256),
     DEFINE_PROP_END_OF_LIST(),
 };

 #ifndef CONFIG_USER_ONLY
 #include "hw/core/sysemu-cpu-ops.h"

 static const struct SysemuCPUOps nios2_sysemu_ops = {
     .get_phys_page_debug = nios2_cpu_get_phys_page_debug,
 };
 #endif

 #include "hw/core/tcg-cpu-ops.h"

 static const struct TCGCPUOps nios2_tcg_ops = {
     .initialize = nios2_tcg_init,
     .restore_state_to_opc = nios2_restore_state_to_opc,

 #ifndef CONFIG_USER_ONLY
     .tlb_fill = nios2_cpu_tlb_fill,
     .cpu_exec_interrupt = nios2_cpu_exec_interrupt,
     .do_interrupt = nios2_cpu_do_interrupt,
     .do_unaligned_access = nios2_cpu_do_unaligned_access,
 #endif /* !CONFIG_USER_ONLY */
 };

 static void nios2_cpu_class_init(ObjectClass *oc, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(oc);
     CPUClass *cc = CPU_CLASS(oc);
     Nios2CPUClass *ncc = NIOS2_CPU_CLASS(oc);
     ResettableClass *rc = RESETTABLE_CLASS(oc);

     device_class_set_parent_realize(dc, nios2_cpu_realizefn,
                                     &ncc->parent_realize);
     device_class_set_props(dc, nios2_properties);
     resettable_class_set_parent_phases(rc, NULL, nios2_cpu_reset_hold, NULL,
                                        &ncc->parent_phases);

     cc->class_by_name = nios2_cpu_class_by_name;
     cc->has_work = nios2_cpu_has_work;
     cc->dump_state = nios2_cpu_dump_state;
     cc->set_pc = nios2_cpu_set_pc;
     cc->get_pc = nios2_cpu_get_pc;
     cc->disas_set_info = nios2_cpu_disas_set_info;
 #ifndef CONFIG_USER_ONLY
     cc->sysemu_ops = &nios2_sysemu_ops;
 #endif
     cc->gdb_read_register = nios2_cpu_gdb_read_register;
     cc->gdb_write_register = nios2_cpu_gdb_write_register;
     cc->gdb_num_core_regs = 49;
     cc->tcg_ops = &nios2_tcg_ops;
 }

 static const TypeInfo nios2_cpu_type_info = {
     .name = TYPE_NIOS2_CPU,
     .parent = TYPE_CPU,
     .instance_size = sizeof(Nios2CPU),
     .instance_init = nios2_cpu_initfn,
     .class_size = sizeof(Nios2CPUClass),
     .class_init = nios2_cpu_class_init,
 };

 static void nios2_cpu_register_types(void)
 {
     type_register_static(&nios2_cpu_type_info);
 }

 type_init(nios2_cpu_register_types)
	/*
	* QEMU Nios II CPU
	*
	* Copyright (c) 2012 Chris Wulff <crwulff@gmail.com>
	*
	* This library is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Lesser General Public
	* License as published by the Free Software Foundation; either
	* version 2.1 of the License, or (at your option) any later version.
	*
	* This library is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General Public
	* License along with this library; if not, see
	* <http://www.gnu.org/licenses/lgpl-2.1.html>
	*/

	#include "qemu/osdep.h"
	#include "qemu/module.h"
	#include "qapi/error.h"
	#include "cpu.h"
	#include "exec/log.h"
	#include "exec/gdbstub.h"
	#include "hw/qdev-properties.h"

	static void nios2_cpu_set_pc(CPUState *cs, vaddr value)
	{
	Nios2CPU *cpu = NIOS2_CPU(cs);
	CPUNios2State *env = &cpu->env;

	env->pc = value;
	}

	static vaddr nios2_cpu_get_pc(CPUState *cs)
	{
	Nios2CPU *cpu = NIOS2_CPU(cs);
	CPUNios2State *env = &cpu->env;

	return env->pc;
	}

	static void nios2_restore_state_to_opc(CPUState *cs,
	const TranslationBlock *tb,
	const uint64_t *data)
	{
	Nios2CPU *cpu = NIOS2_CPU(cs);
	CPUNios2State *env = &cpu->env;

	env->pc = data[0];
	}

	static bool nios2_cpu_has_work(CPUState *cs)
	{
	return cs->interrupt_request & CPU_INTERRUPT_HARD;
	}

	static void nios2_cpu_reset_hold(Object *obj)
	{
	CPUState *cs = CPU(obj);
	Nios2CPU *cpu = NIOS2_CPU(cs);
	Nios2CPUClass *ncc = NIOS2_CPU_GET_CLASS(cpu);
	CPUNios2State *env = &cpu->env;

	if (ncc->parent_phases.hold) {
	ncc->parent_phases.hold(obj);
	}

	memset(env->ctrl, 0, sizeof(env->ctrl));
	env->pc = cpu->reset_addr;

	#if defined(CONFIG_USER_ONLY)
	/* Start in user mode with interrupts enabled. */
	env->ctrl[CR_STATUS] = CR_STATUS_RSIE \| CR_STATUS_U \| CR_STATUS_PIE;
	memset(env->regs, 0, sizeof(env->regs));
	#else
	env->ctrl[CR_STATUS] = CR_STATUS_RSIE;
	nios2_update_crs(env);
	memset(env->shadow_regs, 0, sizeof(env->shadow_regs));
	#endif
	}

	#ifndef CONFIG_USER_ONLY
	static void eic_set_irq(void *opaque, int irq, int level)
	{
	Nios2CPU *cpu = opaque;
	CPUState *cs = CPU(cpu);

	if (level) {
	cpu_interrupt(cs, CPU_INTERRUPT_HARD);
	} else {
	cpu_reset_interrupt(cs, CPU_INTERRUPT_HARD);
	}
	}

	static void iic_set_irq(void *opaque, int irq, int level)
	{
	Nios2CPU *cpu = opaque;
	CPUNios2State *env = &cpu->env;
	CPUState *cs = CPU(cpu);

	env->ctrl[CR_IPENDING] = deposit32(env->ctrl[CR_IPENDING], irq, 1, !!level);

	if (env->ctrl[CR_IPENDING]) {
	cpu_interrupt(cs, CPU_INTERRUPT_HARD);
	} else {
	cpu_reset_interrupt(cs, CPU_INTERRUPT_HARD);
	}
	}
	#endif

	static void nios2_cpu_initfn(Object *obj)
	{
	Nios2CPU *cpu = NIOS2_CPU(obj);

	cpu_set_cpustate_pointers(cpu);

	#if !defined(CONFIG_USER_ONLY)
	mmu_init(&cpu->env);
	#endif
	}

	static ObjectClass nios2_cpu_class_by_name(const char cpu_model)
	{
	return object_class_by_name(TYPE_NIOS2_CPU);
	}

	static void realize_cr_status(CPUState *cs)
	{
	Nios2CPU *cpu = NIOS2_CPU(cs);

	/* Begin with all fields of all registers are reserved. */
	memset(cpu->cr_state, 0, sizeof(cpu->cr_state));

	/*
	* The combination of writable and readonly is the set of all
	* non-reserved fields. We apply writable as a mask to bits,
	* and merge in existing readonly bits, before storing.
	*/
	#define WR_REG(C) cpu->cr_state[C].writable = -1
	#define RO_REG(C) cpu->cr_state[C].readonly = -1
	#define WR_FIELD(C, F) cpu->cr_state[C].writable \|= R_##C##_##F##_MASK
	#define RO_FIELD(C, F) cpu->cr_state[C].readonly \|= R_##C##_##F##_MASK

	WR_FIELD(CR_STATUS, PIE);
	WR_REG(CR_ESTATUS);
	WR_REG(CR_BSTATUS);
	RO_REG(CR_CPUID);
	RO_REG(CR_EXCEPTION);
	WR_REG(CR_BADADDR);

	if (cpu->eic_present) {
	WR_FIELD(CR_STATUS, RSIE);
	RO_FIELD(CR_STATUS, NMI);
	WR_FIELD(CR_STATUS, PRS);
	RO_FIELD(CR_STATUS, CRS);
	WR_FIELD(CR_STATUS, IL);
	WR_FIELD(CR_STATUS, IH);
	} else {
	RO_FIELD(CR_STATUS, RSIE);
	WR_REG(CR_IENABLE);
	RO_REG(CR_IPENDING);
	}

	if (cpu->mmu_present) {
	WR_FIELD(CR_STATUS, U);
	WR_FIELD(CR_STATUS, EH);

	WR_FIELD(CR_PTEADDR, VPN);
	WR_FIELD(CR_PTEADDR, PTBASE);

	RO_FIELD(CR_TLBMISC, D);
	RO_FIELD(CR_TLBMISC, PERM);
	RO_FIELD(CR_TLBMISC, BAD);
	RO_FIELD(CR_TLBMISC, DBL);
	WR_FIELD(CR_TLBMISC, PID);
	WR_FIELD(CR_TLBMISC, WE);
	WR_FIELD(CR_TLBMISC, RD);
	WR_FIELD(CR_TLBMISC, WAY);

	WR_REG(CR_TLBACC);
	}

	/*
	* TODO: ECC (config, eccinj) and MPU (config, mpubase, mpuacc) are
	* unimplemented, so their corresponding control regs remain reserved.
	*/

	#undef WR_REG
	#undef RO_REG
	#undef WR_FIELD
	#undef RO_FIELD
	}

	static void nios2_cpu_realizefn(DeviceState dev, Error *errp)
	{
	CPUState *cs = CPU(dev);
	Nios2CPU *cpu = NIOS2_CPU(cs);
	Nios2CPUClass *ncc = NIOS2_CPU_GET_CLASS(dev);
	Error *local_err = NULL;

	#ifndef CONFIG_USER_ONLY
	if (cpu->eic_present) {
	qdev_init_gpio_in_named(DEVICE(cpu), eic_set_irq, "EIC", 1);
	} else {
	qdev_init_gpio_in_named(DEVICE(cpu), iic_set_irq, "IRQ", 32);
	}
	#endif

	cpu_exec_realizefn(cs, &local_err);
	if (local_err != NULL) {
	error_propagate(errp, local_err);
	return;
	}

	realize_cr_status(cs);
	qemu_init_vcpu(cs);
	cpu_reset(cs);

	/* We have reserved storage for cpuid; might as well use it. */
	cpu->env.ctrl[CR_CPUID] = cs->cpu_index;

	ncc->parent_realize(dev, errp);
	}

	#ifndef CONFIG_USER_ONLY
	static bool eic_take_interrupt(Nios2CPU *cpu)
	{
	CPUNios2State *env = &cpu->env;
	const uint32_t status = env->ctrl[CR_STATUS];

	if (cpu->rnmi) {
	return !(status & CR_STATUS_NMI);
	}
	if (!(status & CR_STATUS_PIE)) {
	return false;
	}
	if (cpu->ril <= FIELD_EX32(status, CR_STATUS, IL)) {
	return false;
	}
	if (cpu->rrs != FIELD_EX32(status, CR_STATUS, CRS)) {
	return true;
	}
	return status & CR_STATUS_RSIE;
	}

	static bool iic_take_interrupt(Nios2CPU *cpu)
	{
	CPUNios2State *env = &cpu->env;

	if (!(env->ctrl[CR_STATUS] & CR_STATUS_PIE)) {
	return false;
	}
	return env->ctrl[CR_IPENDING] & env->ctrl[CR_IENABLE];
	}

	static bool nios2_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
	{
	Nios2CPU *cpu = NIOS2_CPU(cs);

	if (interrupt_request & CPU_INTERRUPT_HARD) {
	if (cpu->eic_present
	? eic_take_interrupt(cpu)
	: iic_take_interrupt(cpu)) {
	cs->exception_index = EXCP_IRQ;
	nios2_cpu_do_interrupt(cs);
	return true;
	}
	}
	return false;
	}
	#endif /* !CONFIG_USER_ONLY */

	static void nios2_cpu_disas_set_info(CPUState cpu, disassemble_info info)
	{
	/* NOTE: NiosII R2 is not supported yet. */
	info->mach = bfd_arch_nios2;
	info->print_insn = print_insn_nios2;
	}

	static int nios2_cpu_gdb_read_register(CPUState cs, GByteArray mem_buf, int n)
	{
	Nios2CPU *cpu = NIOS2_CPU(cs);
	CPUNios2State *env = &cpu->env;
	uint32_t val;

	if (n < 32) { /* GP regs */
	val = env->regs[n];
	} else if (n == 32) { /* PC */
	val = env->pc;
	} else if (n < 49) { /* Status regs */
	unsigned cr = n - 33;
	if (nios2_cr_reserved(&cpu->cr_state[cr])) {
	val = 0;
	} else {
	val = env->ctrl[n - 33];
	}
	} else {
	/* Invalid regs */
	return 0;
	}

	return gdb_get_reg32(mem_buf, val);
	}

	static int nios2_cpu_gdb_write_register(CPUState cs, uint8_t mem_buf, int n)
	{
	Nios2CPU *cpu = NIOS2_CPU(cs);
	CPUClass *cc = CPU_GET_CLASS(cs);
	CPUNios2State *env = &cpu->env;
	uint32_t val;

	if (n > cc->gdb_num_core_regs) {
	return 0;
	}
	val = ldl_p(mem_buf);

	if (n < 32) { /* GP regs */
	env->regs[n] = val;
	} else if (n == 32) { /* PC */
	env->pc = val;
	} else if (n < 49) { /* Status regs */
	unsigned cr = n - 33;
	/* ??? Maybe allow the debugger to write to readonly fields. */
	val &= cpu->cr_state[cr].writable;
	val \|= cpu->cr_state[cr].readonly & env->ctrl[cr];
	env->ctrl[cr] = val;
	} else {
	g_assert_not_reached();
	}

	return 4;
	}

	static Property nios2_properties[] = {
	DEFINE_PROP_BOOL("diverr_present", Nios2CPU, diverr_present, true),
	DEFINE_PROP_BOOL("mmu_present", Nios2CPU, mmu_present, true),
	/* ALTR,pid-num-bits */
	DEFINE_PROP_UINT32("mmu_pid_num_bits", Nios2CPU, pid_num_bits, 8),
	/* ALTR,tlb-num-ways */
	DEFINE_PROP_UINT32("mmu_tlb_num_ways", Nios2CPU, tlb_num_ways, 16),
	/* ALTR,tlb-num-entries */
	DEFINE_PROP_UINT32("mmu_pid_num_entries", Nios2CPU, tlb_num_entries, 256),
	DEFINE_PROP_END_OF_LIST(),
	};

	#ifndef CONFIG_USER_ONLY
	#include "hw/core/sysemu-cpu-ops.h"

	static const struct SysemuCPUOps nios2_sysemu_ops = {
	.get_phys_page_debug = nios2_cpu_get_phys_page_debug,
	};
	#endif

	#include "hw/core/tcg-cpu-ops.h"

	static const struct TCGCPUOps nios2_tcg_ops = {
	.initialize = nios2_tcg_init,
	.restore_state_to_opc = nios2_restore_state_to_opc,

	#ifndef CONFIG_USER_ONLY
	.tlb_fill = nios2_cpu_tlb_fill,
	.cpu_exec_interrupt = nios2_cpu_exec_interrupt,
	.do_interrupt = nios2_cpu_do_interrupt,
	.do_unaligned_access = nios2_cpu_do_unaligned_access,
	#endif /* !CONFIG_USER_ONLY */
	};

	static void nios2_cpu_class_init(ObjectClass oc, void data)
	{
	DeviceClass *dc = DEVICE_CLASS(oc);
	CPUClass *cc = CPU_CLASS(oc);
	Nios2CPUClass *ncc = NIOS2_CPU_CLASS(oc);
	ResettableClass *rc = RESETTABLE_CLASS(oc);

	device_class_set_parent_realize(dc, nios2_cpu_realizefn,
	&ncc->parent_realize);
	device_class_set_props(dc, nios2_properties);
	resettable_class_set_parent_phases(rc, NULL, nios2_cpu_reset_hold, NULL,
	&ncc->parent_phases);

	cc->class_by_name = nios2_cpu_class_by_name;
	cc->has_work = nios2_cpu_has_work;
	cc->dump_state = nios2_cpu_dump_state;
	cc->set_pc = nios2_cpu_set_pc;
	cc->get_pc = nios2_cpu_get_pc;
	cc->disas_set_info = nios2_cpu_disas_set_info;
	#ifndef CONFIG_USER_ONLY
	cc->sysemu_ops = &nios2_sysemu_ops;
	#endif
	cc->gdb_read_register = nios2_cpu_gdb_read_register;
	cc->gdb_write_register = nios2_cpu_gdb_write_register;
	cc->gdb_num_core_regs = 49;
	cc->tcg_ops = &nios2_tcg_ops;
	}

	static const TypeInfo nios2_cpu_type_info = {
	.name = TYPE_NIOS2_CPU,
	.parent = TYPE_CPU,
	.instance_size = sizeof(Nios2CPU),
	.instance_init = nios2_cpu_initfn,
	.class_size = sizeof(Nios2CPUClass),
	.class_init = nios2_cpu_class_init,
	};

	static void nios2_cpu_register_types(void)
	{
	type_register_static(&nios2_cpu_type_info);
	}

	type_init(nios2_cpu_register_types)