Re: [PATCH 10/19] hw/timer/bcm2835: Add the BCM2835 SYS_timer

["Alex Bennée" <alex.bennee@linaro.org>]

Philippe Mathieu-Daudé <f4bug@amsat.org> writes:

> Add the 64-bit free running timer. Do not model the COMPARE register
> (no IRQ generated).
> This timer is used by U-Boot and recent Linux kernels:
> https://github.com/u-boot/u-boot/blob/v2019.07/include/configs/rpi.h#L19
>
> Datasheet used:
> https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf
>
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
> Since which kernels? 4.19 seems to use it.
>
> checkpatch warning:
> WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
> This is OK because the regex are:
>
>   F: hw/*/bcm283*
>   F: include/hw/*/bcm283*
> ---
>  hw/timer/Makefile.objs            |   1 +
>  hw/timer/bcm2835_systmr.c         | 100 ++++++++++++++++++++++++++++++
>  hw/timer/trace-events             |   4 ++
>  include/hw/timer/bcm2835_systmr.h |  30 +++++++++
>  4 files changed, 135 insertions(+)
>  create mode 100644 hw/timer/bcm2835_systmr.c
>  create mode 100644 include/hw/timer/bcm2835_systmr.h
>
> diff --git a/hw/timer/Makefile.objs b/hw/timer/Makefile.objs
> index 123d92c969..696cda5905 100644
> --- a/hw/timer/Makefile.objs
> +++ b/hw/timer/Makefile.objs
> @@ -47,3 +47,4 @@ common-obj-$(CONFIG_SUN4V_RTC) += sun4v-rtc.o
>  common-obj-$(CONFIG_CMSDK_APB_TIMER) += cmsdk-apb-timer.o
>  common-obj-$(CONFIG_CMSDK_APB_DUALTIMER) += cmsdk-apb-dualtimer.o
>  common-obj-$(CONFIG_MSF2) += mss-timer.o
> +common-obj-$(CONFIG_RASPI) += bcm2835_systmr.o
> diff --git a/hw/timer/bcm2835_systmr.c b/hw/timer/bcm2835_systmr.c
> new file mode 100644
> index 0000000000..c4d2b488bd
> --- /dev/null
> +++ b/hw/timer/bcm2835_systmr.c
> @@ -0,0 +1,100 @@
> +/*
> + * BCM2835 SYS timer emulation
> + *
> + * Copyright (C) 2019 Philippe Mathieu-Daudé <f4bug@amsat.org>
> + *
> + * 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.
> + *
> + * Datasheet: BCM2835 ARM Peripherals (C6357-M-1398)
> + * https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf
> + *
> + * Only the free running 64-bit counter is implemented.
> + * The 4 COMPARE registers and the interruption are not implemented.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu/timer.h"
> +#include "qemu/log.h"
> +#include "hw/registerfields.h"
> +#include "hw/timer/bcm2835_systmr.h"
> +#include "trace.h"
> +
> +REG32(CTRL_STATUS,  0x00)
> +REG32(COUNTER_LOW,  0x04)
> +REG32(COUNTER_HIGH, 0x08)
> +REG32(COMPARE0,     0x0c)
> +REG32(COMPARE1,     0x10)
> +REG32(COMPARE2,     0x14)
> +REG32(COMPARE3,     0x18)
> +
> +static uint64_t bcm2835_sys_timer_read(void *opaque, hwaddr offset,
> +                                       unsigned size)
> +{
> +    uint64_t r = 0;
> +
> +    switch (offset) {
> +    case A_CTRL_STATUS:
> +    case A_COMPARE0 ... A_COMPARE3:

Probably worth a LOG_UNIMP in here if we are not going to do it.

> +        break;
> +    case A_COUNTER_LOW:
> +    case A_COUNTER_HIGH:
> +        /* Free running counter at 1MHz */
> +        r = qemu_clock_get_us(QEMU_CLOCK_VIRTUAL);
> +        r >>= 8 * (offset - A_COUNTER_LOW);
> +        r &= UINT32_MAX;
> +        break;
> +    default:
> +        qemu_log_mask(LOG_GUEST_ERROR, "%s: bad offset 0x%" HWADDR_PRIx "\n",
> +                      __func__, offset);
> +        break;
> +    }
> +    trace_bcm2835_sys_timer_read(offset, r);
> +
> +    return r;
> +}
> +
> +static void bcm2835_sys_timer_write(void *opaque, hwaddr offset,
> +                                    uint64_t value, unsigned size)
> +{
> +    trace_bcm2835_sys_timer_write(offset, value);
> +
> +    qemu_log_mask(LOG_UNIMP, "%s: bad offset 0x%" HWADDR_PRIx "\n",
> +                  __func__, offset);
> +}
> +
> +static const MemoryRegionOps bcm2835_sys_timer_ops = {
> +    .read = bcm2835_sys_timer_read,
> +    .write = bcm2835_sys_timer_write,
> +    .endianness = DEVICE_LITTLE_ENDIAN,
> +    .impl = {
> +        .min_access_size = 4,
> +        .max_access_size = 4,
> +    },
> +};
> +
> +static void bcm2835_sys_timer_init(Object *obj)
> +{
> +    SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
> +    BCM2835SysTimerState *s = BCM2835_SYSTIMER(obj);
> +
> +    memory_region_init_io(&s->iomem, obj, &bcm2835_sys_timer_ops,
> +                          s, "bcm2835-sys-timer", 0x20);
> +    sysbus_init_mmio(sbd, &s->iomem);
> +    sysbus_init_irq(sbd, &s->irq);
> +}
> +
> +static const TypeInfo bcm2835_sys_timer_info = {
> +    .name = TYPE_BCM2835_SYSTIMER,
> +    .parent = TYPE_SYS_BUS_DEVICE,
> +    .instance_size = sizeof(BCM2835SysTimerState),
> +    .instance_init = bcm2835_sys_timer_init,
> +};
> +
> +static void bcm2835_sys_timer_register_types(void)
> +{
> +    type_register_static(&bcm2835_sys_timer_info);
> +}
> +
> +type_init(bcm2835_sys_timer_register_types);
> diff --git a/hw/timer/trace-events b/hw/timer/trace-events
> index db02a9142c..81967a1a19 100644
> --- a/hw/timer/trace-events
> +++ b/hw/timer/trace-events
> @@ -87,3 +87,7 @@ pl031_read(uint32_t addr, uint32_t value) "addr 0x%08x value 0x%08x"
>  pl031_write(uint32_t addr, uint32_t value) "addr 0x%08x value 0x%08x"
>  pl031_alarm_raised(void) "alarm raised"
>  pl031_set_alarm(uint32_t ticks) "alarm set for %u ticks"
> +
> +# bcm2835_systmr.c
> +bcm2835_sys_timer_read(uint64_t offset, uint64_t data) "timer read: offset 0x%" PRIx64 " data 0x%" PRIx64
> +bcm2835_sys_timer_write(uint64_t offset, uint64_t data) "timer write: offset 0x%" PRIx64 " data 0x%" PRIx64
> diff --git a/include/hw/timer/bcm2835_systmr.h b/include/hw/timer/bcm2835_systmr.h
> new file mode 100644
> index 0000000000..6ac7f8ec5a
> --- /dev/null
> +++ b/include/hw/timer/bcm2835_systmr.h
> @@ -0,0 +1,30 @@
> +/*
> + * BCM2835 SYS timer emulation
> + *
> + * Copyright (c) 2019 Philippe Mathieu-Daudé <f4bug@amsat.org>
> + *
> + *  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.
> + */
> +
> +#ifndef BCM2835_SYSTIMER_H
> +#define BCM2835_SYSTIMER_H
> +
> +#include "hw/sysbus.h"
> +#include "hw/irq.h"
> +
> +#define TYPE_BCM2835_SYSTIMER "bcm2835-sys-timer"
> +#define BCM2835_SYSTIMER(obj) \
> +    OBJECT_CHECK(BCM2835SysTimerState, (obj), TYPE_BCM2835_SYSTIMER)
> +
> +typedef struct {
> +    /*< private >*/
> +    SysBusDevice parent_obj;
> +
> +    /*< public >*/
> +    MemoryRegion iomem;
> +    qemu_irq irq;
> +} BCM2835SysTimerState;
> +
> +#endif


--
Alex Bennée