Re: [PATCH v1 2/3] hw/timer: Initial commit of Ibex Timer

[Bin Meng]

On Mon, May 31, 2021 at 12:33 PM Alistair Francis
<alistair.francis@wdc.com> wrote:

Please write some commit message, for example, what is supported in
this initial version, and what is not.

>
> Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
> ---
>  include/hw/timer/ibex_timer.h |  52 ++++++
>  hw/timer/ibex_timer.c         | 305 ++++++++++++++++++++++++++++++++++
>  MAINTAINERS                   |   6 +-
>  hw/timer/meson.build          |   1 +
>  4 files changed, 360 insertions(+), 4 deletions(-)
>  create mode 100644 include/hw/timer/ibex_timer.h
>  create mode 100644 hw/timer/ibex_timer.c
>
> diff --git a/include/hw/timer/ibex_timer.h b/include/hw/timer/ibex_timer.h
> new file mode 100644
> index 0000000000..6a43537003
> --- /dev/null
> +++ b/include/hw/timer/ibex_timer.h
> @@ -0,0 +1,52 @@
> +/*
> + * QEMU lowRISC Ibex Timer device
> + *
> + * Copyright (c) 2021 Western Digital
> + *
> + * 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.
> + */
> +
> +#ifndef HW_IBEX_TIMER_H
> +#define HW_IBEX_TIMER_H
> +
> +#include "hw/sysbus.h"
> +
> +#define TYPE_IBEX_TIMER "ibex-timer"
> +OBJECT_DECLARE_SIMPLE_TYPE(IbexTimerState, IBEX_TIMER)
> +
> +struct IbexTimerState {
> +    /* <private> */
> +    SysBusDevice parent_obj;
> +
> +    /* <public> */
> +    MemoryRegion mmio;
> +
> +    uint32_t timer_ctrl;
> +    uint32_t timer_cfg0;
> +    uint32_t timer_compare_lower0;
> +    uint32_t timer_compare_upper0;
> +    uint32_t timer_intr_enable;
> +    uint32_t timer_intr_state;
> +    uint32_t timer_intr_test;
> +
> +    uint32_t timebase_freq;
> +
> +    qemu_irq irq;
> +};
> +#endif /* HW_IBEX_TIMER_H */
> diff --git a/hw/timer/ibex_timer.c b/hw/timer/ibex_timer.c
> new file mode 100644
> index 0000000000..0a1030b15f
> --- /dev/null
> +++ b/hw/timer/ibex_timer.c
> @@ -0,0 +1,305 @@
> +/*
> + * QEMU lowRISC Ibex Timer device
> + *
> + * Copyright (c) 2021 Western Digital
> + *
> + * For details check the documentation here:
> + *    https://docs.opentitan.org/hw/ip/rv_timer/doc/
> + *
> + * 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 "qemu/osdep.h"
> +#include "qemu/log.h"
> +#include "qemu/timer.h"
> +#include "hw/timer/ibex_timer.h"
> +#include "hw/irq.h"
> +#include "hw/qdev-properties.h"
> +#include "target/riscv/cpu.h"
> +#include "migration/vmstate.h"
> +
> +REG32(CTRL, 0x00)
> +    FIELD(CTRL, ACTIVE, 0, 1)
> +REG32(CFG0, 0x100)
> +    FIELD(CFG0, PRESCALE, 0, 12)
> +    FIELD(CFG0, STEP, 16, 8)
> +REG32(LOWER0, 0x104)
> +REG32(UPPER0, 0x108)
> +REG32(COMPARE_LOWER0, 0x10C)
> +REG32(COMPARE_UPPER0, 0x110)
> +REG32(INTR_ENABLE, 0x114)
> +    FIELD(INTR_ENABLE, IE_0, 0, 1)
> +REG32(INTR_STATE, 0x118)
> +    FIELD(INTR_STATE, IS_0, 0, 1)
> +REG32(INTR_TEST, 0x11C)
> +    FIELD(INTR_TEST, T_0, 0, 1)
> +
> +static uint64_t cpu_riscv_read_rtc(uint32_t timebase_freq)
> +{
> +    return muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL),
> +                    timebase_freq, NANOSECONDS_PER_SECOND);
> +}
> +
> +static void ibex_timer_update_irqs(IbexTimerState *s)
> +{
> +    CPUState *cs = qemu_get_cpu(0);
> +    RISCVCPU *cpu = RISCV_CPU(cs);
> +    uint64_t value = s->timer_compare_lower0 |
> +                         ((uint64_t)s->timer_compare_upper0 << 32);
> +    uint64_t next, diff;
> +    uint64_t now = cpu_riscv_read_rtc(s->timebase_freq);
> +
> +    if (!(s->timer_ctrl & R_CTRL_ACTIVE_MASK)) {
> +        /* Timer isn't active */
> +        return;
> +    }

I am not sure if compiler can optimize such, but this if block can be
put at the beginning of this function.

> +
> +    /* Update the CPUs mtimecmp */
> +    cpu->env.timecmp = value;

The existing env.timecmp seems to be only valid for CLINT. Should we
move it out of env?

> +
> +    if (cpu->env.timecmp <= now) {
> +        /*
> +         * If the mtimecmp was in the past raise the interrupt now.
> +         */
> +        riscv_cpu_update_mip(cpu, MIP_MTIP, BOOL_TO_MASK(1));
> +        if (s->timer_intr_enable & R_INTR_ENABLE_IE_0_MASK) {
> +            s->timer_intr_state |= R_INTR_STATE_IS_0_MASK;
> +            qemu_set_irq(s->irq, true);
> +        }
> +        return;
> +    }
> +
> +    /* Setup a timer to trigger the interrupt in the future */
> +    riscv_cpu_update_mip(cpu, MIP_MTIP, BOOL_TO_MASK(0));
> +    qemu_set_irq(s->irq, false);
> +
> +    diff = cpu->env.timecmp - now;
> +    next = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
> +                                 muldiv64(diff,
> +                                          NANOSECONDS_PER_SECOND,
> +                                          s->timebase_freq);
> +
> +    if (next < qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL)) {
> +        /* We overflowed the timer, just set it as large as we can */
> +        timer_mod(cpu->env.timer, 0x0FFFFFFFFFFFFFFF);

Should it be 0x7FFFFFFFFFFFFFFF?

> +    } else {
> +        timer_mod(cpu->env.timer, next);
> +    }
> +}
> +
> +static void ibex_timer_cb(void *opaque)
> +{
> +    IbexTimerState *s = opaque;
> +    CPUState *cs = qemu_get_cpu(0);
> +    RISCVCPU *cpu = RISCV_CPU(cs);
> +
> +    riscv_cpu_update_mip(cpu, MIP_MTIP, BOOL_TO_MASK(1));
> +    if (s->timer_intr_enable & R_INTR_ENABLE_IE_0_MASK) {
> +        s->timer_intr_state |= R_INTR_STATE_IS_0_MASK;
> +        qemu_set_irq(s->irq, true);
> +    }
> +}
> +
> +static void ibex_timer_reset(DeviceState *dev)
> +{
> +    IbexTimerState *s = IBEX_TIMER(dev);
> +
> +    CPUState *cpu = qemu_get_cpu(0);
> +    CPURISCVState *env = cpu->env_ptr;
> +    env->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
> +                              &ibex_timer_cb, s);
> +    env->timecmp = 0;
> +
> +    s->timer_ctrl = 0x00000000;
> +    s->timer_cfg0 = 0x00000000;
> +    s->timer_compare_lower0 = 0x0000003c;
> +    s->timer_compare_upper0 = 0x00000000;

The reset values seem not to conform with the spec?

> +    s->timer_intr_enable = 0x00000000;
> +    s->timer_intr_state = 0x00000000;
> +    s->timer_intr_test = 0x00000000;
> +
> +    ibex_timer_update_irqs(s);
> +}
> +
> +static uint64_t ibex_timer_read(void *opaque, hwaddr addr,
> +                                       unsigned int size)
> +{
> +    IbexTimerState *s = opaque;
> +    uint64_t now = cpu_riscv_read_rtc(s->timebase_freq);
> +    uint64_t retvalue = 0;
> +
> +    switch (addr >> 2) {
> +    case R_CTRL:
> +        retvalue = s->timer_ctrl;
> +        break;
> +    case R_CFG0:
> +        retvalue = s->timer_cfg0;
> +        break;
> +    case R_LOWER0:
> +        retvalue = now;
> +        break;
> +    case R_UPPER0:
> +        retvalue = now >> 32;
> +        break;
> +    case R_COMPARE_LOWER0:
> +        retvalue = s->timer_compare_lower0;
> +        break;
> +    case R_COMPARE_UPPER0:
> +        retvalue = s->timer_compare_upper0;
> +        break;
> +    case R_INTR_ENABLE:
> +        retvalue = s->timer_intr_enable;
> +        break;
> +    case R_INTR_STATE:
> +        retvalue = s->timer_intr_state;
> +        break;
> +    case R_INTR_TEST:
> +        retvalue = s->timer_intr_test;
> +        break;
> +    default:
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "%s: Bad offset 0x%"HWADDR_PRIx"\n", __func__, addr);
> +        return 0;
> +    }
> +
> +    return retvalue;
> +}
> +
> +static void ibex_timer_write(void *opaque, hwaddr addr,
> +                             uint64_t val64, unsigned int size)
> +{
> +    IbexTimerState *s = opaque;
> +    uint32_t val = val64;
> +
> +    switch (addr >> 2) {
> +    case R_CTRL:
> +        s->timer_ctrl = val;
> +        break;
> +    case R_CFG0:
> +        qemu_log_mask(LOG_UNIMP, "Changing prescale or step not supported");
> +        s->timer_cfg0 = val;
> +        break;
> +    case R_LOWER0:
> +        qemu_log_mask(LOG_UNIMP, "Changing timer value is not supported");
> +        break;
> +    case R_UPPER0:
> +        qemu_log_mask(LOG_UNIMP, "Changing timer value is not supported");
> +        break;
> +    case R_COMPARE_LOWER0:
> +        s->timer_compare_lower0 = val;
> +        ibex_timer_update_irqs(s);
> +        break;
> +    case R_COMPARE_UPPER0:
> +        s->timer_compare_upper0 = val;
> +        ibex_timer_update_irqs(s);
> +        break;
> +    case R_INTR_ENABLE:
> +        s->timer_intr_enable = val;

Does this register connect to MIE?

> +        break;
> +    case R_INTR_STATE:
> +        /* Write 1 to clear */
> +        s->timer_intr_state &= ~val;
> +        break;
> +    case R_INTR_TEST:
> +        s->timer_intr_test = val;
> +        if (s->timer_intr_enable &
> +            s->timer_intr_test &
> +            R_INTR_ENABLE_IE_0_MASK) {
> +            s->timer_intr_state |= R_INTR_STATE_IS_0_MASK;
> +            qemu_set_irq(s->irq, true);
> +        }
> +        break;
> +    default:
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "%s: Bad offset 0x%"HWADDR_PRIx"\n", __func__, addr);
> +    }
> +}
> +
> +static const MemoryRegionOps ibex_timer_ops = {
> +    .read = ibex_timer_read,
> +    .write = ibex_timer_write,
> +    .endianness = DEVICE_NATIVE_ENDIAN,
> +    .impl.min_access_size = 4,
> +    .impl.max_access_size = 4,
> +};
> +
> +static int ibex_timer_post_load(void *opaque, int version_id)
> +{
> +    IbexTimerState *s = opaque;
> +
> +    ibex_timer_update_irqs(s);
> +    return 0;
> +}
> +
> +static const VMStateDescription vmstate_ibex_timer = {
> +    .name = TYPE_IBEX_TIMER,
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .post_load = ibex_timer_post_load,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_UINT32(timer_ctrl, IbexTimerState),
> +        VMSTATE_UINT32(timer_cfg0, IbexTimerState),
> +        VMSTATE_UINT32(timer_compare_lower0, IbexTimerState),
> +        VMSTATE_UINT32(timer_compare_upper0, IbexTimerState),
> +        VMSTATE_UINT32(timer_intr_enable, IbexTimerState),
> +        VMSTATE_UINT32(timer_intr_state, IbexTimerState),
> +        VMSTATE_UINT32(timer_intr_test, IbexTimerState),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
> +static Property ibex_timer_properties[] = {
> +    DEFINE_PROP_UINT32("timebase-freq", IbexTimerState, timebase_freq, 
> 10000),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
> +static void ibex_timer_init(Object *obj)
> +{
> +    IbexTimerState *s = IBEX_TIMER(obj);
> +
> +    sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->irq);
> +
> +    memory_region_init_io(&s->mmio, obj, &ibex_timer_ops, s,
> +                          TYPE_IBEX_TIMER, 0x400);
> +    sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio);
> +}
> +
> +static void ibex_timer_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +
> +    dc->reset = ibex_timer_reset;
> +    dc->vmsd = &vmstate_ibex_timer;
> +    device_class_set_props(dc, ibex_timer_properties);
> +}
> +
> +static const TypeInfo ibex_timer_info = {
> +    .name          = TYPE_IBEX_TIMER,
> +    .parent        = TYPE_SYS_BUS_DEVICE,
> +    .instance_size = sizeof(IbexTimerState),
> +    .instance_init = ibex_timer_init,
> +    .class_init    = ibex_timer_class_init,
> +};
> +
> +static void ibex_timer_register_types(void)
> +{
> +    type_register_static(&ibex_timer_info);
> +}
> +
> +type_init(ibex_timer_register_types)
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 5f55404f2f..c46d4e281e 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1355,11 +1355,9 @@ M: Alistair Francis <Alistair.Francis@wdc.com>
>  L: qemu-riscv@nongnu.org
>  S: Supported
>  F: hw/riscv/opentitan.c
> -F: hw/char/ibex_uart.c
> -F: hw/intc/ibex_plic.c
> +F: hw/*/ibex_*.c
>  F: include/hw/riscv/opentitan.h
> -F: include/hw/char/ibex_uart.h
> -F: include/hw/intc/ibex_plic.h
> +F: include/hw/*/ibex_*.h
>
>  Microchip PolarFire SoC Icicle Kit
>  M: Bin Meng <bin.meng@windriver.com>
> diff --git a/hw/timer/meson.build b/hw/timer/meson.build
> index 157f540ecd..1aa3cd2284 100644
> --- a/hw/timer/meson.build
> +++ b/hw/timer/meson.build
> @@ -33,5 +33,6 @@ softmmu_ss.add(when: 'CONFIG_SSE_COUNTER', if_true: 
> files('sse-counter.c'))
>  softmmu_ss.add(when: 'CONFIG_SSE_TIMER', if_true: files('sse-timer.c'))
>  softmmu_ss.add(when: 'CONFIG_STM32F2XX_TIMER', if_true: 
> files('stm32f2xx_timer.c'))
>  softmmu_ss.add(when: 'CONFIG_XILINX', if_true: files('xilinx_timer.c'))
> +specific_ss.add(when: 'CONFIG_IBEX', if_true: files('ibex_timer.c'))
>
>  specific_ss.add(when: 'CONFIG_AVR_TIMER16', if_true: files('avr_timer16.c'))
> --

Regards,
Bin